EP4736282A1

EP4736282A1 - External cavity laser assembly with stable output frequency

Info

Publication number: EP4736282A1
Application number: EP24742788.3A
Authority: EP
Inventors: Alexander Jason WHITMORE; Michael Pushkarsky; Daniel MULKEY; Marcus LANOVAZ; Carrie KISHIMOTO; Jacob SCHALCH; Miles Weida; Allen Priest
Original assignee: Daylight Solutions Inc
Current assignee: Daylight Solutions Inc
Priority date: 2023-06-27
Filing date: 2024-06-21
Publication date: 2026-05-06
Also published as: WO2025006351A1

Abstract

A laser assembly (10) that generates a first beam (40) includes an emitter (16), a transmission grating assembly (20), and a redirector assembly (22). The emitter (16) emits an emitter beam (16a) from a first facet (16c). The transmission grating assembly (20) is positioned in the path of the emitter beam (16a), and the transmission grating assembly (20) diffracts the emitter beam (16a) into the first beam (40) and a second beam (42) during transmission through the transmission grating assembly (20). The redirector assembly (22) receives the second beam (42) and directs a redirected beam (44) at the transmission grating assembly (20) to form an external cavity.

Description

EXTERNAL CAVITY LASER ASSEMBLY WITH STABLE OUTPUT FREQUENCY

RELATED APPLICATION

[0001] As far as permitted, the contents of (i) U.S. Patent Application No: 63/510,619, filed on June 27, 2023, and entitled “External Cavity Laser Assembly With Stable Output Frequency”, (ii) U.S. Patent Application No: 63/624,691 , filed on January 24, 2024, and entitled “External Cavity Laser Assembly With Stable Output Frequency”, and (iii) U.S. Patent Application No: 63/625,833, filed on January 26, 2024, and entitled “External Cavity Laser Assembly With Stable Output Frequency” are incorporated herein by reference.

BACKGROUND

[0002] Laser assemblies can be used in many fields such as, laboratories, Lidar, medical diagnostics, pollution monitoring, leak detection, analytical instruments, homeland security, aerospace, remote chemical sensing, industrial process control, and jamming of heat-seeking missiles. One type of laser assembly is an external cavity laser diode assembly. Unfortunately, lab grade external cavity laser diode assemblies are large, expensive, have inaccurate tuning, have inaccurate pointing, and have a free running linewidth that is highly susceptible to acoustics and vibrations.

[0003] Manufacturers are always searching for ways to reduce size, reduce cost, improve tuning accuracy, improve pointing, improve running linewidth stability, improve beam quality, and improve power output of these laser assemblies.

SUMMARY

[0004] One implementation is directed to a laser assembly that generates a first beam. The laser assembly can include an emitter, a transmission grating assembly, and a redirector assembly. The emitter emits an emitter beam from a first facet. The transmission grating assembly is positioned in the path of the emitter beam, and the transmission grating assembly diffracts the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly. The redirector assembly that receives the second beam and directs a redirected beam at the transmission grating assembly.

[0005] One implementation is directed to a laser assembly that generates a first beam. The laser assembly can include an emitter, a transmission grating assembly, and a redirector assembly. The emitter emits an emitter beam from a first facet. The transmission grating assembly is positioned in the path of the emitter beam, and the transmission grating assembly diffracts the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly. The redirector assembly receives the second beam and directs a redirected beam at the transmission grating assembly.

[0006] The transmission grating assembly diffracts the redirected beam into a redirected cavity beam during transmission through the transmission grating assembly that is directed to the first facet of the emitter. Further, the transmission grating assembly can diffract the redirected beam into a redirected output beam during transmission through the transmission grating assembly.

[0007] The redirector assembly can include a redirector and a redirector mover that selectively moves the redirector to selectively tune a center wavelength of the emitter beam. The redirector mover can include a guide assembly that guides the movement of the redirector, and a redirector actuator assembly that moves the redirector. The guide assembly can be a flexure. The redirector actuator assembly can include a piezoelectric actuator.

[0008] In one design, the redirector mover selectively moves the redirector approximately about a selected pivot axis that allows for mode hop free tuning over a large spectral range.

[0009] Additionally, the laser assembly can include a system controller that selectively controls a current to the emitter to selectively tune the center wavelength of the emitter beam.

[0010] The emitter includes a second facet that forms a first cavity end of an external cavity, and the redirector assembly forms a second cavity end of the external cavity. In this design, the transmission grating is positioned the between cavity ends along an optical path of the external cavity, and the transmission grating functions as an output coupler. The redirector assembly can include a retroreflector or porro prism. [0011] Additionally, in any of the designs provided herein, the laser assembly can include one or more of: (i) a beam shaper positioned in the path of the first beam that shapes the first beam; (ii) an isolator positioned in the path of the first beam, wherein the isolator attenuates light from being directed back at the transmission grating (e.g., set to the fundamental wavelength of the external cavity); (iii) a pointer adjuster assembly that adjusts the pointing of the first beam; (iv) a polarization adjuster assembly that adjusts the polarization of the first beam; (v) a coupling lens assembly that focuses the first beam onto a lens focal point; and/or (vi) a non-linear crystal, such as a second harmonic generator that receives the first beam and changes a frequency of the first beam.

[0012] As non-exclusive examples, the transmission grating can include a volume phase holographic grating; a surface relief etched transmission grating; or a replica transmission grating. The transmission grating has a periodic structure that is aligned along a grating axis. Further, a grating mover assembly can selectively move the transmission grating along the grating axis to change the power of the beam. Additionally, or alternatively, the transmission grating can be rotated about the transverse axis to adjust the diffraction experienced by the emitter beam. More specifically, the transmission grating is rotatable about the transverse axis to adjust a power ratio of the beams.

[0013] In one implementation, the redirector assembly includes a redirector and a guide assembly, an actuator, and a lever arm that couples the guide assembly to the actuator.

[0014] In another implementation, the laser assembly includes: an emitter that emits an emitter beam from a first facet; a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating, the transmission grating having a periodic structure that is aligned along a grating axis; and a grating mover assembly that selectively moves the transmission grating along the grating axis.

[0015] In one design, a redirector receives the second beam and directs a redirected beam at the transmission grating. In this design, (i) the redirector and the transmission grating create a gaussian shaped filter to the effective gain of the emitter; (ii) a longitudinal mode of the emitter closest to the center of the filter will have the highest gain and lase; and (iii) the grating mover assembly selectively moves the transmission grating along the grating axis to selectively adjust the longitudinal mode without shifting the filter.

[0016] In one implementation, the grating mover assembly selectively moves the transmission grating along the grating axis to selectively position a desired longitudinal mode to the center of the filter. Additionally, or alternatively, the grating mover assembly can selectively move the transmission grating along the grating axis to selectively shift a parasitic undulation of the filter. With this design, the grating mover assembly selectively moves the transmission grating along the grating axis (i) to maximize an optical power of the first beam, and/or (ii) to reduce modulation of the optical power of the first beam while tuning of the laser assembly.

[0017] In yet another implementation, the laser assembly includes an emitter that emits an emitter beam from a first facet; and a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating, the transmission grating being a having a periodic structure aligned along a grating axis and a transverse axis that is transverse to the grating axis; and wherein movement of the transmission grating about the transverse axis adjusts a diffraction experienced by the emitter beam.

[0018] In still another implementation, the present invention is directed to a laser assembly including: an emitter that emits an emitter beam from a first facet; a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam that are transmitted through the transmission grating; and a redirector. The transmission grating can include a volume phase holographic grating; and the redirector receives the second beam and redirects a redirected beam at the transmission grating.

[0019] In another implementation, the laser assembly includes: an emitter that emits an emitter beam from a first facet; a redirector that directs a redirected beam back to the emitter to form an external cavity; a flexure that guides movement of the redirector; and a redirector actuator assembly that selectively bends the flexure to move and position the redirector to selectively change the path length of the external cavity. The flexure can have (i) low stiffness in one degree of freedom, and (ii) high stiffness in the other five degrees of freedom. The flexure can include a vibration damping mechanism. The redirector actuator assembly can include wires, and the wires can be attached to the mounting base to inhibit vibration. [0020] In still another implementation, the laser assembly includes: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; a coupling lens assembly that focuses the output beam onto the fiber inlet facet; and a pointer adjuster that adjusts the relative position between the output beam and the fiber inlet facet.

[0021] In yet another implementation, the laser assembly includes: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; a coupling lens assembly that focuses the output beam onto the fiber inlet facet; and a polarization adjuster assembly that selectively adjusts a polarization of the output beam.

[0022] In another implementation, the present invention is directed to a beam adjuster assembly for adjusting an inlet beam with four degrees of freedom. The beam adjuster assembly can include: an adjuster base; a first pointer adjuster that receives the inlet beam, the first pointer adjuster being a wedged shaped element; and a second pointer adjuster that receives the beam that exits the first pointer adjuster, the second pointer adjuster being a wedged shaped element. In this design, (i) the first pointer adjuster and the second pointer adjuster can be selectively and independently rotated relative to the adjuster base to selectively adjust the pointing of the inlet beam wherein two degrees of freedom, and/or (ii) the first pointer adjuster and the second pointer adjuster can be selectively and independently tilted relative to the adjuster base to selectively adjust the translation of the inlet beam with two degrees of freedom.

[0023] In this design, the adjuster base can include (i) a first receiver that is shaped to receive a portion of the first pointer adjuster, and (ii) a second receiver that is shaped to receive a portion of the second pointer adjuster. At least one of the receivers can be a socket that is shaped like a portion of a sphere. Additionally, at least one of the pointer adjusters can have a spherical shaped segment. An adjuster faster can fixedly secure each pointer adjuster to the adjuster base.

[0024] In still another design, the laser assembly includes: an emitter that emits a laser beam; a first frame that encircles the emitter; and a second frame that encircles the first frame and the emitter to thermally isolate the emitter from the surrounding environment and provide stable fluid space between the frames. The first frame can include a first frame top having a thickness of at least two millimeters, and can be made of a material having a relatively high thermal conductivity coefficient.

[0025] Moreover, the laser assembly can include an emission attenuator that attenuates emissions, and extends from the second frame towards the first frame. In this design, the beam exiting the laser assembly is directed through an attenuator aperture in the emission attenuator.

[0026] In another design, the laser assembly includes: an emitter that emits an emitter beam; an optical fiber assembly including a fiber cover made of a material that attenuates radiated electromagnetic emissions from the ambient from entering the laser assembly; and a coupling lens assembly that focuses the beam onto the fiber inlet facet.

[0027] In still another implementation, the laser assembly includes an emitter that emits a laser beam; a redirector that forms an external cavity with the emitter; and a non-linear crystal that receives the beam exiting from the external cavity. The nonlinear crystal can include a waveguide. The non-linear crystal can be a second harmonic generator. In this design, the second harmonic generator includes a waveguide with coated facets, and the waveguide has an effective area of at least 3- 5 microns, with good efficiency.

[0028] Additionally, the light exiting the second harmonic generator can be butt- coupled to a fiber inlet facet of a fiber. In this design, a separation distance between an output facet of the waveguide and the fiber inlet facet is within 1-3 microns, or is less than 5, 10, 20, 50, 75 or 100 microns. Stated differently, in alternative implementations, the separation distance is less than 1 , 2, 3, 5, 10, 20, 40, 75, or 100 microns.

[0029] In another implementation, the laser assembly includes: a laser frame; an emitter that emits an emitter beam, the emitter being positioned in the laser frame; and a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; the transmission grating assembly being positioned in the laser frame. The emitter and the transmission grating assembly can be selectively changed to change the wavelength (wavelength range) of the output beam.

[0030] In one design, the laser assembly can include heatsink geometry and an emitter flex circuit that is designed to alternatively to receive different emitters in the same package. The laser frame can include a mounting base, and a pivot axis of the transmission grating can be moved and set relative to the mounting base for different emitters. Stated differently, the laser assembly can include a heatsink that couples the emitter to the laser frame. In certain designs, the heatsink has a geometry designed to selectively receive a different emitter on the heatsink.

[0031] In still another implementation, the laser assembly includes: a laser frame including a mounting base; an emitter that emits a beam, the emitter being coupled to the mounting base; and a polarization adjuster assembly that selectively adjusts a polarization of the beam. In this design, the polarization adjuster assembly includes (i) a polarization adjuster that can be selectively moved relative to the mounting base to adjust the polarization, the polarization adjuster having anisotropic properties; (ii) an adjuster mount that is coupled to the mounting base; and (iii) an adjuster fastener that couples the polarization adjuster to the adjuster mount.

[0032] In this design, the polarization adjuster has a first coefficient of thermal expansion along a first axis, and a second coefficient of thermal expansion along a second axis, that is different from the first coefficient of thermal expansion. As a result thereof, the polarization adjuster expands at different rates along different axes. For example, the second coefficient of thermal expansion can be greater than the first coefficient of thermal expansion. The second coefficient of thermal expansion can be at least 10, 500, 100, 200 or 300 percent greater than the first coefficient of thermal expansion.

[0033] In one design, the first coefficient of thermal expansion along the first axis, approximately matches with a coefficient of thermal expansion for the mounting base and/or the adjuster mount. As used herein, approximately matches means within 1 , 2, 10, 20, or 40 percent.

[0034] The polarization adjuster can be mounted so that the first axis is substantially parallel with an upper surface of the mounting base. The adjuster fastener can include a spaced apart pair of adhesive spots that are aligned approximately along the first axis.

[0035] The present invention is also directed to an element mover assembly that selectively moves an optical element relative to a frame. The element mover assembly can include: a guide assembly that guides movement of the optical element, the guide assembly being coupled to the frame and the optical element; and an element actuator assembly that selectively moves the guide assembly and the position the optical element. The element actuator assembly can include an element actuator, and a lever arm that pivots about a lever pivot axis. In this design, the lever arm is coupled to the element actuator and the guide assembly, and the element actuator selectively pivots the lever arm about the lever pivot axis to selectively move the guide assembly and the optical element.

[0036] The lever arm can have (i) an input arm length that is defined by the distance between where the element actuator engages the lever arm and the lever pivot axis, and (ii) an output arm length that is defined by the distance between where the lever arm engages the guide assembly and the lever pivot axis; wherein the output arm length is greater than the input arm length. The output arm length can be at least 1 .2 times greater than the input arm length.

[0037] Additionally, the element mover assembly can include a coupler assembly that couples the lever arm to the guide assembly in a fashion such that non- tangential forces are inhibited from being imparted on the guide assembly by the lever arm. In one design, the coupler assembly includes a coupler flexure. In another design, the coupler assembly includes a point contact and flat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

[0039] Figure 1 is a simplified top illustration of an embodiment of a laser assembly;

[0040] Figure 2 is a simplified illustration of a pointer adjuster and a portion of a mounting base;

[0041] Figure 3 is a simplified illustration of a polarization adjuster and a portion of the mounting base;

[0042] Figure 4A is an end view of a portion of the mounting base, a coupling lens assembly, and an optical fiber assembly;

[0043] Figure 4B is a side view of the portion of the mounting base, the coupling lens assembly, and the optical fiber assembly of Figure 4A;

[0044] Figure 5 is a side view of a portion of the mounting base, an alternative implementation of the coupling lens assembly, and the optical fiber assembly; [0045] Figure 6A is a simplified top view of a portion of another implementation of the laser assembly;

[0046] Figure 6B is a simplified side view of a portion of the mounting base, and a transmission grating assembly in a first position;

[0047] Figure 6C is a simplified side view of a portion of the mounting base, and the transmission grating assembly in a second position;

[0048] Figure 6D is a simplified side view of a portion of the mounting base, and the transmission grating assembly in a third position;

[0049] Figure 7A is a simplified top view of another portion of the laser assembly;

[0050] Figure 7B is a simplified top view of the portion of the laser assembly of Figure 7A at another time;

[0051] Figure 7C is a simplified top view of the portion of the laser assembly of Figure 7A at yet another time;

[0052] Figure 8 is a simplified top view of yet another portion of the laser assembly;

[0053] Figure 9A is simplified top view of still another portion of the laser assembly;

[0054] Figure 9B is simplified top view of the laser assembly of Figure 9A with an alternative mounting;

[0055] Figure 9C is simplified top view of the laser assembly of Figure 9A with yet another, alternative mounting;

[0056] Figures 10A and 10B are simplified top views of another portion of the laser assembly at different times;

[0057] Figure 11 is a simplified top view of yet another portion of the laser assembly;

[0058] Figure 12 is a simplified top view of still another portion of the laser assembly;

[0059] Figure 13A is a simplified top view of another portion of the laser assembly;

[0060] Figure 13B is a simplified side view of the guide assembly of Figure 13A;

[0061] Figure 14 is a simplified top view of still another portion of the laser assembly; [0062] Figure 15A is a partly exploded, perspective view of another implementation of the laser assembly;

[0063] Figure 15B is a cut-away view of the laser assembly of Figure 15A taken on line 15B-15B in Figure 15A;

[0064] Figure 15C is a perspective view of the laser assembly of Figure 15A with the outer frame top removed;

[0065] Figures 15D and 15E are alternative perspective views, and Figure 15F is a top view of the laser assembly of Figure 15A with the outer frame top, and the inner frame top removed;

[0066] Figure 15G is a perspective view of a portion of the laser assembly of Figure 15A;

[0067] Figure 15H is a perspective view of another portion of the laser assembly of Figure 15A;

[0068] Figure 15I is a perspective view of a still portion of the laser assembly of Figure 15A;

[0069] Figure 15J is a top view of a redirector assembly;

[0070] Figure 15K is a perspective view of the redirector assembly of Figure 151;

[0071] Figure 15L is a perspective view of a pointer adjuster assembly;

[0072] Figure 15M is a perspective view of a portion of the pointer adjuster assembly of Figure 15L;

[0073] Figure 15N is a simplified illustration of the pointer adjuster assembly at two different pointing positions;

[0074] Figure 150 is a simplified illustration of the pointer adjuster assembly at two more, different pointing positions;

[0075] Figure 15P is a perspective view of a portion of an optical isolator and a polarization adjuster assembly;

[0076] Figure 15Q, Figure 15R, and Figure 15S are alternative views of a polarization adjuster;

[0077] Figure 16 is a simplified top view of another implementation of the redirector assembly;

[0078] Figure 17 is a simplified side view of yet another implementation of the redirector assembly and a portion of the mounting base; [0079] Figure 18 is a simplified side view of still another implementation of the redirector assembly and a portion of the mounting base;

[0080] Figure 19 is a top perspective view of a portion of another implementation of the laser assembly;

[0081] Figure 20 is a top perspective view of a portion of still another implementation of the laser assembly;

[0082] Figure 21 is a top perspective view of a portion of yet another implementation of the laser assembly;

[0083] Figure 22A and Figure 22 B are alternative top perspective views of a portion of yet another implementation of the laser assembly;

[0084] Figure 23 is a perspective view of a portion of still another implementation of the laser assembly;

[0085] Figure 24 is a simplified top perspective view of still another implementation of a laser assembly;

[0086] Figure 25A is a simplified, top view of an element assembly;

[0087] Figure 25B is a simplified top view of a portion of the element assembly of Figure 25A;

[0088] Figure 26 is a simplified, top view of another implementation of an element assembly;

[0089] Figure 27 is a simplified, top view of still another implementation of an element assembly;

[0090] Figure 28A is a simplified top perspective view of yet another implementation of a laser assembly;

[0091] Figure 28B is a simplified top view of the laser assembly of Figure 28A;

[0092] Figure 29 is a simplified top view of still another implementation of a laser assembly; and

[0093] Figure 30 is a simplified top view of yet another implementation of a laser assembly.

DESCRIPTION

[0094] Figure 1 is simplified top illustration of a first embodiment of a laser assembly 10 that generates an assembly output beam 12 (illustrated with an arrow). In certain embodiments, the laser assembly 10 includes (i) a laser frame 14; (ii) an emitter 16 that generates an emitter beam 16a (illustrated as an arrow); (iii) an emitter lens 18, (iv) a transmission grating assembly 20 including a transmission grating 20a positioned in the path of the emitter beam 16a, (v) a redirector assembly 22 that functions an output coupler, (vi) a beam shaper 24 that shapes the output beam 12, (vii) an isolator 26, (viii) a pointer adjuster assembly 28, (ix) a polarization adjuster assembly 30, (x) a coupling lens assembly 32, (xi) an optical fiber assembly 34 having a fiber inlet facet 34a, and (xii) a system controller 36 that controls the operation of the laser assembly 10. In this design, the output beam 12 is fiber coupled into the optical fiber assembly 34.

[0095] Additionally, Figure 1 illustrates a power supply 38 (e.g. a battery, the electrical grid, or a generator) that provides electrical power to the system controller 36. Further, the laser assembly 10 can be secured to a rigid mount (not shown) such as a test or experimental bench, a frame of a vehicle or aircraft, or other structure.

[0096] The design of each of the components of the laser assembly 10 can be varied to change the characteristics of the output beam 12. Moreover, the laser assembly 10 can be designed to include more or fewer components than are illustrated in Figure 1 . For example, the laser assembly 10 can be designed without one or more of (i) the beam shaper 24, (ii) the isolator 26, (iii) the pointer adjuster assembly 28, (iv) the polarization adjuster assembly 30, (v) the coupling lens assembly 32, and/or (vi) the optical fiber assembly 34. In a specific example, without the optical fiber assembly 34, the output beam 12 could be launched into free space.

[0097] Additionally, one or more of the facets of the components can be slightly angled, and the optical path of the output beam 12 can be skewed to reduce reflections and minimize parasitic cavities that can influence the power and/or stability of the output beam 12.

[0098] As an overview, the unique arrangement disclosed herein allows for a wavelength tunable, external cavity laser assembly 10 having a small form factor, that is relatively optomechanically insensitive to vibration, and that is relatively inexpensive to manufacture. For example, in the non-exclusive implementation of Figure 1 , the laser assembly 10 utilizes a unique external cavity design that (i) is relatively easy to manufacture, (ii) is not very complex, (iii) has a relatively high Merit function, (iv) can be accurately tuned over a relatively large tuning range without mode hops, and (v) is optomechanically insensitive to movement. As a result thereof, the laser assembly 10 is more rugged, has improved tuning accuracy, has improved beam pointing, has improved running linewidth stability, has improved beam quality, and has improved power output.

[0099] Moreover, in certain implementations, the unique external cavity design provided herein allows for the selective adjustment and control of the phase of a free spectral range of a primary cavity, and/or the phase of a free spectral range of a parasitic cavity. This allows for improved optical power, and reduces modulation of the optical power of the output beam 12 during tuning of the laser assembly 10.

[00100] Additionally, in certain implementations, the unique external cavity design provided herein allows for the selective adjustment of reflectivity of the transmission grating 20a to optimize the optical power of the output beam 12.

[00101] Further, in certain implementations, the pointer adjuster assembly 28 improves the pointing of the output beam 12 to maximize that amount of output beam 12 that is coupled to the optical fiber assembly 34. As a result thereof, the laser assembly 10 has improved power output.

[00102] Furthermore, in certain implementations, the redirector assembly 22 is uniquely designed to allow for mode hop free tuning of the laser assembly 10 over a relatively large spectral range.

[00103] The designs described herein provide the following benefits: (i) providing a stable output wavelength that can be accurately tuned over a relatively large range; (ii) getting more power into the output beam 12 while preserving good quality; (iii) getting high power out of the laser assembly 10 with a relatively small footprint; and/or (iv) providing a rugged laser assembly 10.

[00104] As a non-exclusive example, the laser assembly 10 can be designed so that the output beam 12 has an optical power of between 0.5 to 10 watts. Stated in anotherfashion, in alternative, non-exclusive embodiments, the laser assembly 10 can be designed so that the output beam 12 has an optical power of at least approximately 0.5, 1 , 2, 5, or 10 watts. However, optical powers of less than or greater than those values are possible.

[00105] Some of the Figures include an orientation system. For example, Figure 1 includes an orientation system that is referenced to the laser frame 14, and that includes an X axis, a Y axis that is orthogonal to the X axis, and a Z axis that is orthogonal to the X and Y axes. It should be noted that these axes can also be referred to as the first, second and third axes. [00106] The laser frame 14 is rigid, thermally stable, supports the other components of the laser assembly 10, and maintains the precise alignment of the components of the laser assembly 10. In the simplified implementation of Figure 1 , the laser frame 14 is illustrated as including a mounting base 14a, a frame housing 14b (illustrated in cut-away), and a temperature controller 14c. However, other designs of the laser frame 14 are possible.

[00107] In the non-exclusive implementation of Figure 1 , the mounting base 14a is a flat rigid plate that supports (i) the emitter 16; (ii) the emitter lens 18, (iii) the transmission grating assembly 20; (iv) the redirector assembly 22; (v) the beam shaper 24; (vi) the isolator 26, (vii) the pointer adjuster assembly 28, (viii) the polarization adjuster assembly 30, (ix) the coupling lens assembly 32, and (x) the optical fiber assembly 34. However, other designs of the mounting base 14a are possible, and/or the mounting base 14a can be designed to support fewer components than the design illustrated in Figure 1.

[00108] In the non-exclusive implementation of Figure 1 , the frame housing 14b is generally rectangular box shaped and encircles most of the other components. In this design, the frame housing 14b includes a housing base 14ba, four housing sides 14bb, and a housing top (not shown). With this design, the frame housing 14b can provide a controlled environment for the other components of the laser assembly 10. As alternative, non-exclusive examples, the controlled environment can be a vacuum, an inert gas, or anotherfluid. For example, the controlled environment can be selected to match and provide the best environment for the emitter 16. In one implementation, the controlled environment can be a fluid that improves the reliability of the emitter 16. Still alternatively, for example, desiccant or another drying agent can be positioned in the frame housing 14b to trap moisture and/or gases that could absorb laser emissions, cause corrosion, and/or to cause condensation. In a different design, the frame housing 14b can be unsealed.

[00109] Additionally, in the non-exclusive implementation of Figure 1 , the frame housing 14b includes (i) a first feedthrough 14bc that allows the system controller 36 to be electrically connected to the emitter 16 without compromising the controlled environment in the frame housing 14b; (ii) a second feedthrough 14bd that allows the system controller 36 to be electrically connected to the temperature controller 14c without compromising the controlled environment in the frame housing 14b; (iii) a third feedthrough 14be that allows the system controller 36 to be electrically connected to the redirector assembly 22 without compromising the controlled environment in the frame housing 14b; and (iv) a fourth feedthrough 14bf that allows the optical fiber assembly 34 to pass through the frame housing 14ba without compromising the controlled environment in the frame housing 14b. Some or all of these feedthroughs may be combined.

[00110] The temperature controller 14c actively controls the temperature of one or more of the components of the laser assembly 10. For example, the temperature controller 14c can actively control the temperature of the emitter 16 and/or the mounting base 14a. In certain implementations, it is important that the mounting base 14a is thermally stable to inhibit unwanted changes to the optical path length of the external cavity, and to inhibit unwanted shifts in the positions of the components.

[00111] In the non-exclusive implementation of Figure 1 , the temperature controller 14c can include (i) a thermoelectric cooler 14ca that is positioned between the mounting base 14a and the housing base 14ba; and (ii) one or more temperature sensors 14cb (e.g., a thermistor) that provides feedback for closed loop control of the temperature of the mounting base 14a and/or the emitter 16. In the non-exclusive design illustrated in Figure 1 , the mounting base 14a is secured to the housing base 14ba with the thermoelectric cooler 14ca therebetween. Alternatively, for example, the temperature controller 14c can include (i) a thermal plate (not shown) having internal passageways; and (ii) one or more pumps (not shown), chillers (not shown), heaters (not shown), and/or reservoirs (not shown) that cooperate to circulate a hot or cold circulation fluid (not shown) through the thermal plate.

[00112] The emitter 16 generates the emitter beam 16a along an emitter axis 16b. The design of the emitter 16 can be varied to achieve the desired characteristics of the output beam 12. In certain implementations, the emitter beam 16b emitted from the emitter 16 is diverging and non-collimated. In one implementation, the emitter 16 has a front, first facet 16c and an opposed rear, second facet 16d, and the emitter 16 is designed to only emit from the front facet 16c. In this embodiment, the back facet 16d is coated with a reflective dielectric or metal/dielectric coating to minimize optical losses from the back facet 16d and to allow the back facet 16d to function a first cavity end of a primary external cavity. Further, the front facet 16c can include an anti- reflective dielectric coating to minimize coupled cavity effects within the laser assembly 10. For example, the coating on the front facet 16c can be optimized to minimize reflectivity across the available gain-bandwidth of the emitter 16. In one non-exclusive embodiment, the anti-reflective coating can have a reflectivity of less than approximately two percent, and the highly reflective coating can have a reflectivity of greater than ninety percent.

[00113] In one, non-exclusive implementation, the emitter 16 can be a laser diode. For example, the emitter 16 can be a short wavelength laser diode or a long wavelength laser diode. As non-exclusive examples, the laser diode can be Gallium Antimonide, Gallium arsenide, indium phosphide, gallium nitride, Indium Gallium Phosphide, Indium Gallium Nitride, Aluminum Gallium Arsenide, Aluminum Gallium Indium Phoshide, or Indium Gallium Arsenide Phosphide. Alternatively, for example, the emitter 16 can be a Quantum Cascade (“QC”) gain medium, or an interband cascade laser.

[00114] Non-exclusive examples of suitable wavelengths for the emitter 16 can include within the ultraviolet range, the visible range, the near infrared range, the infrared range, the mid-infrared range, of the far infrared range.

[00115] The emitter lens 18 collimates the emitter beam 16a emitted from the emitter 16. In Figure 1 , the emitter lens 18 is coaxial with the emitter axis 16b, and the emitter lens 18 creates a diffraction limited or near diffraction limited, collimated beam that is directed at the transmission grating assembly 20. As non-exclusive examples, the emitter lens 18 can be aspheric; conic; spherical; plano-convex; bi-convex; a meniscus lens; or double sided. Further, the emitter lens 18 can be transparent in the lasing optical bandwidth of the emitter beam 16a, and be anti-reflective coated on both sides.

[00116] The transmission grating 20a is positioned in the path of the emitter beam 16a that has been collimated by the emitter lens 18, and the transmission grating 20a is a part of the primary external cavity of the laser assembly 10. In one implementation, the transmission grating 20a is designed and positioned so that the collimated emitter beam 16a that impinges on the transmission grating 20a is transmitted through, and diffracted into at least a first beam 40 that is directed along a first beam axis 40a, and a second beam 42 that is directed along a second beam axis 42a that is different from the first beam axis 40a. In one non-exclusive implementation, the first beam 40 is the zeroth order of diffraction (M=0) of the emitter beam 16a; and the second beam 42 is the first order of diffraction (M=+1 or -1 ) of the emitter beam 16a. However, each of the beams 40, 42 can be an order that is different than this example. For example, each of the beams 40, 42 can be the second order of diffraction (M=+2 or M= -2).

[00117] In non-exclusive implementation of Figure 1 , the first beam 40 is sequentially directed through (i) the beam shaper 24, (ii) the isolator 26, (iii) the pointer adjuster assembly 28, (iv) the polarization adjuster assembly 30, and (v) the coupling lens assembly 32 to become the output beam 12 that is coupled to the optical fiber assembly 34. In this example, the first beam 40 can be referred to as (i) a shaped first beam 40b after it has passed through the beam shaper; (ii) an isolated first beam 40c after it has passed through the isolator 26; (iii) a pointed first beam 40d after it has passed through the pointer adjuster assembly 28, (iv) a polarized first beam 40e after it has passed through the polarization adjuster assembly 30, and (v) a focused first beam 40f after it has passed through the coupling lens assembly 32. It should be noted that at each of these locations, the light can generically be referred to as the first beam. Further, it should be noted that the focused first beam 40f is the output beam 12 that is coupled to the optical fiber assembly 34.

[00118] In contrast, as provided above, the laser assembly 10 can designed without one or more of (i) the beam shaper 24, (ii) the isolator 26, (iii) the pointer adjuster assembly 28, (iv) the polarization adjuster assembly 30, and (v) the coupling lens assembly 32; and the first beam 40 does not travel through one or more of (i) the beam shaper 24, (ii) the isolator 26, (iii) the pointer adjuster assembly 28, (iv) the polarization adjuster assembly 30, and (v) the coupling lens assembly 32.

[00119] The second beam 42 is directed at the redirector assembly 22. With this design, the second beam 42 is part of the primary external cavity, while the first beam 40 has exited the primary external cavity.

[00120] The design of the transmission grating 20a can be varied to achieve the desired performance of the laser assembly 10. For example, the design of the transmission grating 20a can be selected to achieve the desired power ratio of the first beam 40 and the second beam 42. Further, the type and/or design of transmission grating 20a can be selected based on the design of the emitter 16 because certain transmission gratings 20a have better diffraction efficiency for certain polarizations. For example, certain transmission gratings 20a disclosed herein can be easily engineered and designed to improve the efficiency of the grating 20a to certain polarizations. As a specific example, certain laser diodes have a linear polarization, and volume phase holographic gratings can be engineered to have good diffraction efficiency for a linear polarization.

[00121] The transmission grating 20a is an optical component having a periodic structure that is aligned along a grating axis (not shown in Figure 1 ). In one implementation, the transmission grating 20a is an optical component having a plurality of transmissive or hollow slits or grooves (not shown) that are spaced apart along the grating axis. Alternatively, for example, the transmission grating 20a can be a volume phase holographic grating (“VPH”) that has a plurality of changes in the index of refraction in the medium that are spaced apart along the grating axis.

[00122] Non-exclusive examples of a suitable transmission grating 20a include (i) a holographic grating such as volume phase holographic grating; (ii) an etched grating, such as fused silica; (iii) a ruled grating; or (iv) a replicated (“replica”) transmission grating. In specific examples, the transmission grating 20a can be a volume phase holographic grating that is a dichromatized gelatin grating, or a photothermal refractive glass grating. Alternatively, for example, the transmission grating 20a can be a surface relief etched transmission grating.

[00123] The redirector assembly 22 receives the second beam 42 and redirects the second beam 42 as a redirected beam 44 back at the transmission grating 20a along the second beam axis 42a. With this design, the redirected beam 44 that impinges upon the transmission grating 20a is transmitted through, and diffracted into at least (i) a redirected first beam 44a (illustrated with a dashed arrow) that is directed along a redirected first beam axis 44aa; and (ii) a redirected second beam 44b that is directed along the emitter axis 16b and retraces the path back to the emitter lens 18 and the emitter 16. In one non-exclusive implementation, the redirected first beam 44a is the zeroth order of diffraction (M=0) of the redirected beam 44, and the redirected second beam 44b is the first order of diffraction (M=1) of the redirected beam 44. It should be noted that (i) the redirected first beam 44a can also be referred to as a “redirected output beam” or “second output beam”; and/or (ii) the redirected second beam 44b can also be referred to as a “redirected cavity beam”.

[00124] With this design, the redirector assembly 22 functions as an output coupler and a second cavity end of the primary external cavity. As a result thereof, the second cavity end formed by the redirector assembly 22 cooperates with the first cavity end formed by the back, second facet 16d of the emitter 16 to create the primary external cavity of the laser assembly 10. It should be noted that the light in the primary external cavity follows an optical path having an optical path length between cavity ends, and the transmission grating 20a is positioned the between cavity ends along the optical path.

[00125] The type of redirector assembly 22 utilized can be varied to achieve the desired performance of the laser assembly 10. In one implementation, the redirector assembly 22 includes (i) a redirector 46 that redirects the second beam 42 and forms the second cavity end; and (ii) a redirector mover 48 that precisely and selectively moves the redirector 46 (and the second cavity end) to adjust the optical path length of the primary external cavity, and the primary lasing center wavelength of the primary external cavity.

[00126] A non-exclusive example of a suitable redirector 46 can include a retroreflector such as a porro prism. The retroreflector can be coated with a material having a very high reflectivity for the spectral range of the second beam 42.

[00127] The redirector mover 48 is controlled by the system controller 36 to precisely move the redirector 46 to precisely adjust the optical path length of the primary external cavity. This allows for the precise tuning of the center wavelength of the output beam 12. In one, non-exclusive implementation, the redirector mover 48 precisely moves the redirector 46 in a closed loop fashion about a selected pivot axis (not shown in Figure 1 ). In certain implementations, the selected pivot axis is chosen because movement of the redirector 46 about that axis inhibits mode hops during the tuning of the center wavelength. Stated alternatively, in certain designs, the redirector mover 48 moves the redirector 46 in a fashion that inhibits mode hops while tuning over a desired spectral range. In one, non-exclusive implementation, the redirector mover 48 selectively pivots the redirector 46 about the selected pivot axis to allow for mode hop free tuning. The location of the selected pivot axis will depend upon the design and location of the components of the laser assembly 10.

[00128] In one implementation, the redirector mover 48 can include a redirector actuator assembly 48a (illustrated as a box), a guide assembly 48b (illustrated as a box) for guiding movement (e.g., pivoting) of the redirector 46, and/or a sensor assembly 48c (illustrated as a box) for sensing the position of the redirector 46 for closed loop control of the position of the redirector 46.

[00129] As non-exclusive examples, the actuator assembly 48a can include one or more (i) piezoelectric actuator(s), such as shear piezos (e.g., bidirectional, passive or active running), and/or piezo clips; (ii) bimetallic strip(s); (iii) thermoelectric cooler(s); (iv) heater(s), (v) voice coil(s), (vi) stepper motor(s), (vii) solenoid(s), (viii) electrostriction, (ix) motor(s), and/or (x) actuator(s).

[00130] As non-exclusive examples, the guide assembly 48b can include one or more (i) flexure(s); (ii) bearing(s); and/or (iii) other rotary guide(s). In a specific example, the guide assembly 48b can be a flexure made of nitinol.

[00131] As non-exclusive examples, the sensor assembly 48c can include one or more (i) encoder(s); (ii) interferometer(s); and/or (iii) other sensors.

[00132] In the external cavity arrangement of Figure 1 , the position of the redirector 46 will primarily dictate (i) the optical path length of the primary external cavity, (ii) the center wavelength of the primary external cavity, and (iii) the primary, center wavelength of the emitter beam 16a from the emitter 16, and the output beam 12. Stated differently, the center wavelength of the emitter beam 16a and the output beam 12 are tied to the position of the redirector 46. With this design, the redirector 46 is precisely moved to tune the center wavelength, without moving the transmission grating 20a, and without influencing the path of the first beam 40 (M=0) that becomes the output beam 12. As a result, the wavelength of the output beam 12 can be accurately selected and maintained, the pointing of the output beam 12 is stable and insensitive to tuning of the wavelength of the output beam 12, and the coupling efficiency into the optical fiber assembly 34 is improved because the pointing is stable.

[00133] In Figure 1 , the redirector 46 is precisely moved to make relatively slow and rough (large) tuning of optical path length of the primary external cavity, and the center wavelength of the emitter beam 16a.

[00134] In contrast, the system controller 36 can selectively adjust the current directed to the emitter 16 to selectively control (change) the index of refraction of the emitter 16. The index of refraction influences the optical path length of the emitter 16 and the optical path length of the primary external cavity. As provided above, the optical path length of the primary external cavity influences the lasing center wavelength of the emitter beam 16a. As a result thereof, the system controller 36 can selectively adjust the current directed to the emitter 16 to selectively make relatively rapid, and fine (small) changes to the lasing center wavelength of the emitter beam 16a. Additionally, a resistor (not shown) can be positioned near the emitter or near the waveguide of the emitter to make changes the optical path length of the emitter 16. [00135] As provided above, the redirected second beam 44b is directed along the emitter axis 16b back to the emitter lens 18 and the emitter 16. In contrast, the redirected first beam 44a is directed along a redirected first beam axis 44aa. As a result thereof, with the cavity design in Figure 1 , the redirected first beam 44a can be used as a second output beam. For example, the redirected first beam 44a can be directed a device 50 that utilizes and/or captures the redirected first beam 44a. As non-exclusive examples, the device 50 can be a component that utilizes the redirected first beam 44a, or a sensor that senses one or more conditions of the redirected first beam 44a, such as the wavelength, polarization or power. Alternatively, the device 50 can be a light absorber that captures the redirected first beam 44a and inhibits the redirected first beam 44a from bouncing around in the laser assembly 10. In Figure 1 , the device 50 is illustrated within the laser frame 14. Alternatively, the device 50 can be positioned outside the laser frame 14.

[00136] It should be noted that the design of the transmission grating 20a can additionally or alternatively be selected to achieve the desired power ratio of the redirected first beam 44a and the redirected second beam 44b.

[00137] As provided above, in the non-exclusive implementation of Figure 1 , the first beam 40 exits the transmission grating 20a along the first beam axis 40a and is directed at the beam shaper 24. As a result thereof, the beam shaper 24 shapes the first beam 40 that has been transmitted through the transmission grating 20a. In certain designs, the first beam 40 is not perfectly circular, and the optical fiber assembly 34 is circular. In one example, the beam shaper 24 reshapes the first beam 40 to have circular cross-sectional shape to match the optical fiber assembly 34. Alternatively, the beam shaper 24 can cause the first beam 40 to have a shape other than circular.

[00138] As non-exclusive examples, the beam shaper 24 can include one or more optical elements, including one or more: (i) axicon lenses; (ii) powell lenses; (iii) powell prisms; (iv) metasurfaces; (v) diffractive optical elements; (vi) engineered diffusers; and/or (vii) aspheric corrector plates.

[00139] The isolator 26 inhibits light from the subsequent components along the optical path of the first beam 40 from being reflected back to the transmission grating 20a and the external cavity. For example, (i) the device (not shown) that receives the output beam 12 from the optical fiber assembly 34, (ii) the fiber inlet facet 34a, (iii) the coupling lens assembly 30, (iv) the pointer adjuster assembly 28, and/or (v) the polarization adjuster assembly 30 can reflect a small portion of the beam in the opposite direction back towards the transmission grating 20a and into the emitter 16. These reflections can cause a portion of the light in the emitter 16 to lase at an unwanted wavelength, and reduce the power of the output beam 12 at the target wavelength. In one implementation, the isolator 26 is an optical component that only allows light to transmit in one direction (e.g., right to left in Figure 1 ). For example, the isolator 26 can be based on a faraday rotator.

[00140] In Figure 1 , the light that exits the isolator 26 is directed at the pointer adjuster assembly 28. In this design, the pointer adjuster assembly 28 is controlled and/or adjusted to precisely adjust the pointing of the output beam 12. As a result thereof, the output beam 12 is accurately pointed, and can be accurately centered and focused on the fiber inlet facet 34a to maximize fiber coupling of the output beam 12.

[00141] As provided herein, during operation of the laser assembly 10, temperature cycles, stress relief, and/or vibration can cause one or more of the components to move slightly, and adversely influence the pointing of the output beam 12. In certain designs, the laser assembly 10 can be temperature cycled and/or vibrated to get the components to settle in position for final alignment. Subsequently, the pointer adjuster assembly 28 can be used to adjust and correct the pointing of the output beam 12.

[00142] A number of different designs of the pointer adjuster assembly 28 are provided herein. In one non-exclusive implementation, the pointer adjuster assembly 28 includes (i) a first pointer adjuster 28a having a wedged window 28aa, and (ii) a second pointer adjuster 28b having a second wedged window 28ba; and the wedged windows 28aa, 28ba are arranged in series and spaced apart so that the light travels through the first wedged window 28aa to the second wedged window 28ba. In certain designs, one or both wedged windows 28aa, 28ba can be individually and selectively moved to adjust the pointing of the output beam 12. With this design, for example, after the laser assembly 10 is ready for final alignment, the wedged windows 28aa, 28ba can be individually moved and adjusted until a measured output power in the optical fiber assembly 34 is maximized. Generally, maximum output power is achieved when the output beam 12 is properly focused on the fiber inlet facet 34a. When the maximum is achieved, the wedged windows 28aa, 28ba can be fixedly secured to the mounting base 14a. [00143] For example, the wedged windows 28aa, 28ba can be a Risley pair that can be rotated until that output beam 12 is properly focused. These Risley pairs are relatively insensitive to subsequent movement.

[00144] In an alternative design, the pointer adjuster assembly 28 can include only one, or more than two pointer adjusters 28a, 28b.

[00145] In yet another alternative design, (i) the first pointer adjuster 28a can additionally include a first window mover 28ab that can be controlled to selectively move the first wedged window 28aa relative to the mounting base 14a; and/or (ii) the second pointer adjuster 28b can include a second window mover 28bb that can be controlled to selectively move the second wedged window 28ba relative to the mounting base 14a. With this design, for example, the power output in the optical fiber assembly 34 can be continuously or intermittently monitored, and the system controller 36 (using feedback regarding power output) can selectively control (i) the first window mover 28ab to actively position the first wedged window 28aa; and/or (ii) the second window mover 28bb to actively position the second wedged window 28ba to maintain the maximum power output. As a non-exclusive example, each window mover 28ab, 28bb can selectively rotate its respective wedged window 28aa, 28ba. Each window mover 28ab, 28bb can include one or more rotary actuator(s), motor(s) or another type of actuator. Further, one or more window sensors (not shown) can provide feedback to the system controller 36 regarding the rotational position of one or both wedged window 28aa, 28ba.

[00146] Additionally, or alternatively, the pointer adjuster assembly 28 can include a selectively steerable mirror (not shown) or a tunable prism (not shown). Still alternatively or additionally, the pointer adjuster assembly 28 could include a liquid lens (not shown), and the current to the liquid lens can be selectively controlled to control the shape of liquid lens and the pointing of the output beam 12.

[00147] In Figure 1 , the light that exits the pointer adjuster assembly 28 is directed at the polarization adjuster assembly 30. In this design, the polarization adjuster assembly 30 is controlled and/or adjusted to precisely adjust the polarization of the output beam 12. As a result thereof, the output beam 12 will have a polarization that best matches the optical fiber assembly 34 and/or the device (or specific application) that utilizes the output beam 12 from the optical fiber assembly 34.

[00148] In certain implementations, the optical fiber assembly 34 is a polarization maintaining optical fiber (e.g., includes stress rods that maintain the polarization). In a specific example, the device that utilizes the output beam 12 from the optical fiber assembly 34 is designed to function best with an output beam 12 having a desired polarization (e.g., a linear polarization). In this example, the emitter 16 can be designed so that the first beam 40 leaving the transmission grating 20a has the desired polarization (e.g., linear polarization), and the optical fiber assembly 34 can be designed to maintain light having the desired polarization (e.g., the linear polarization). However, alignment and other issues can cause the first beam 40 to not exactly have the desired polarization. With the present design, the polarization adjuster assembly 30 can be adjusted to change (if necessary) the polarization of the first beam 40 so that the output beam 12 has the desired polarization (e.g., linear polarization) before it enters the optical fiber assembly 34.

[00149] In one non-exclusive implementation, the polarization adjuster assembly 30 includes (i) a first polarization adjuster 30a having a first waveplate 30aa, and (ii) a second polarization adjuster 30b having a second waveplate 30ba; and the waveplates 30aa, 30ba are arranged in series and spaced apart so that the light travels through the first waveplate 30aa to the second waveplate 30ba. In certain designs, one or both waveplates 30aa, 30ba can be individually and selectively moved to adjust the polarization of the output beam 12. The two waveplates 30aa, 30ba allow for the fine adjustment of the polarization of the output beam 12 in space. As a non-exclusive example, one of the waveplates 30aa, 30ab can be a half waveplate, and the other of the waveplates 30ba, 30aa can be a quarter waveplate. With this design, for example, after the laser assembly 10 has been temperature cycled and/or vibrated, and is ready for final adjustment, the waveplates 30aa, 30ba can be individually moved and adjusted until a measured polarization of the output beam 12 in the optical fiber assembly 34 is the same as the desired polarization. When the desired polarization is achieved, the waveplates 30aa, 30ba can be fixedly secured to the mounting base 14a.

[00150] In an alternative design, the polarization adjuster assembly 30 can include only one, or more than two polarization adjusters 30a, 30b.

[00151] In yet another, alternative design, (i) the first polarization adjuster 30a can be designed to include a first waveplate mover 30ab that can be controlled to selectively move the first waveplate 30aa relative to the mounting base 14a; and/or (ii) the second polarization adjuster 30b can be designed to include a second waveplate mover 30bb that can be controlled to selectively move the second waveplate 30ba relative to the mounting base 14a. With this design, for example, the polarization of the output beam 12 in the optical fiber assembly 34 can be continuously or intermittently monitored, and the system controller 36 (using feedback regarding polarization) can selectively control (i) the first waveplate mover 30ab to actively position the first waveplate 30aa; and/or (ii) the second waveplate mover 30bb to actively position the second waveplate 30ba to achieve the desired polarization. As a non-exclusive example, each waveplate mover 30ab, 30bb can selectively rotate its respective waveplate 30aa, 30ba. Each waveplate mover 30ab, 30bb can include one or more rotary actuator(s), motor(s) or another type of actuators. Further, one or more waveplate sensors (not shown) can provide feedback to the system controller 36 regarding the rotational position of one or both waveplates 30aa, 30ba.

[00152] The coupling lens assembly 32 directs and couples the output beam 12 to the fiber inlet facet 34a of the optical fiber assembly 34. More specifically, the coupling lens assembly 32 precisely focuses the output beam 12 onto the fiber inlet facet 34a of the optical fiber 34. In one non-exclusive implementation, the coupling lens assembly 32 includes a coupling lens having a lens focal point, and the coupling lens focuses the output beam 12 onto the fiber inlet facet 34a which is positioned at the lens focal point.

[00153] The optical fiber assembly 34 carries and transmits the output beam 12. As provided above, the optical fiber assembly 34 can be a polarization maintaining optical fiber. Alternatively, the optical fiber assembly 34 may be designed to not maintain the polarization.

[00154] The system controller 36 controls the operation of the components of the laser assembly 10. For example, the system controller 36 can include one or more processors 36a, and one or more electronic storage devices 36b. The system controller 36 can be a centralized unit or a distributed system. In certain embodiments, the system controller 36 can control the electron injection current to the emitter 16, control the redirector assembly 22 to control the position of the redirector 46, and control the temperature controller 14c to control the temperature of the mounting base 14a. For example, the system controller 36 can continuously direct power to the emitter 16. Alternatively, for example, the system controller 36 can direct power in a pulsed fashion to the emitter 16.

[00155] Additionally, in certain designs, the system controller 36 can control one or more of the window movers 28ab, 28bb, and the waveplate movers 30ab, 30bb. [00156] Additionally and optionally, the laser system 10 can include a feedback system 52 that monitors one or more of the optical power, wavelength, polarization and/or other characteristic of the output beam 12 in the optical fiber assembly 34, and provides feedback to the system controller 36. For example, the feedback system 52 can include one or more sensors. With this feedback, system controller 36 can selectively adjust one or more components of the laser assembly 10 in a closed loop fashion.

[00157] In the non-exclusive example of Figure 1 , the optical fiber assembly 34 includes a fiber splitter 52a that directs a small portion of the output beam 12 to the feedback system 52. As non-exclusive examples, the fiber splitter 52a can direct less than approximately one, two, or three percent of the output beam 12 to the feedback system 52.

[00158] Alternatively, for example, the feedback system 52 could analyze light that is reflected off of the fiber inlet facet 34a and/or light from another location or source. As non-exclusive examples, the feedback system 52 can get light from (i) a side polishing fiber, (ii) a tapered fiber, (iii) a coating on a ferrule, (iv) an evanescent coupling, (v) back scattering, and/or (vi) coated or uncoated fiber facet reflection.

[00159] In Figure 1 , the feedback system 52 is illustrated within the laser frame 14. Alternatively, the feedback system 52 can be positioned outside the laser frame 14.

[00160] Figure 2 is a simplified side view of a non-exclusive implementation of a first pointer adjuster 228a and a portion of the mounting base 214a. In this implementation, the first pointer adjuster 228a can be used in the laser assembly 10 of Figure 1 or another type of laser assembly. Further, the laser assembly 10 can include a second pointer adjuster 28b (illustrated in Figure 1) that can be somewhat similar to the first pointer adjuster 228a of Figure 2.

[00161] In Figure 2, the first pointer adjuster 228a includes a wedged window 228aa, a rigid window mount 228ac that is fixedly secured to the mounting base 214a, and a window fastener 228ad that fixedly secures the first wedged window 228aa to the window mount 228ac.

[00162] Figure 2 includes an orientation system that is referenced to the first pointer adjuster 228a, and that includes a T axis, a U axis that is orthogonal to the T axis, and a V axis that is orthogonal to the T and U axes. It should be noted that these axes can also be referred to as the first, second and third axes. [00163] As a non-exclusive example, the window mount 228ac can be a rigid block that includes a semicircular shaped groove that is sized and shaped to receive a portion of the wedged window 228aa. Further, the window fastener 228ad can be an adhesive or another type of fastener, such as one or more bolts, or welds.

[00164] With the present design, for example, after the laser assembly 10 (illustrated in Figure 1 ) is ready for final alignment (e.g., after temperature and/or vibration cycling), the wedged window 228aa, and or the second wedged window 28ba (illustrated in Figure 1 ) can be individually moved about and/or along one or axes. For example, the wedged window 228aa, and or the second wedged window 28ba (illustrated in Figure 1 ) can be individually moved about the II axis, along the T axis, and/or along the V axis relative to the mounting base 214a and the first beam 40 (illustrated in Figure 1), and adjusted until a measured output power in the optical fiber assembly 34 (illustrated in Figure 1) is maximized. When the maximum is achieved, the window fastener 228ad can be used to fixedly secure the first wedged window 228aa to the window mount 228ac.

[00165] Figure 3 is a simplified view of a non-exclusive implementation of the first polarization adjuster 330a and a portion of the mounting base 314a. In this implementation, the first polarization adjuster 330a can be used in the laser assembly 10 of Figure 1 , or another type of laser assembly. Further, the laser assembly 10 can include a second polarization adjuster 30b (illustrated in Figure 1) that can be somewhat similar to the first polarization adjuster 330a of Figure 2.

[00166] In Figure 3, the first polarization adjuster 330a can include a waveplate 330aa, a rigid waveplate mount 330ac that is secured to the mounting base 314a, and a waveplate fastener 330ad that fixedly secures the waveplate 330aa to the waveplate mount 330ac.

[00167] Figure 3 includes an orientation system is referenced to the polarization adjuster 330, and includes a Q axis, a R axis that is orthogonal to the Q axis, and a S axis that is orthogonal to the Q and R axes. It should be noted that these axes can also be referred to as the first, second and third axes.

[00168] As a non-exclusive example, the waveplate mount 330ac can be a rigid block that includes a semicircular shaped groove that is sized and shaped to receive a portion of the waveplate 330aa. Further, the waveplate fastener 330ad can be an adhesive or another type of fastener, such as one or more bolts, or welds. [00169] With the present design, for example, after the laser assembly 10 (illustrated in Figure 1 ) is ready for final alignment (e.g., after temperature and/or vibration cycling), the waveplate 330aa, and or the second waveplate 30ba (illustrated in Figure 1 ) can be individually moved about and/or along one or axes. For example, the waveplate 330aa, and or the second waveplate 30ba can be individually moved about the R axis, along the Q axis, and/or along the S axis relative to the mounting base 314a and the first beam 40 (illustrated in Figure 1 ), and adjusted until the desired polarization of the output beam 12 (illustrated in Figure 1) is achieved. Subsequently, the waveplate fastener 330ad can be used to fixedly secure the first waveplate 330aa to the waveplate mount 330ac.

[00170] Figure 4A is an end view and Figure 4B is a side view of a portion of the mounting base 414a, and another implementation of a coupling lens assembly 432, and an optical fiber assembly 434.

[00171] Figures 4A and 4B include an orientation system is referenced to the fiber inlet facet 434a, and includes an N axis, an O axis that is orthogonal to the N axis, and a P axis that is orthogonal to the N and O axes. It should be noted that these axes can also be referred to as the first, second and third axes.

[00172] In one non-exclusive example, the optical fiber assembly 434 includes the optical fiber 434b having the fiber inlet facet 434a, and a fiber holder 434c that couples and secures the optical fiber 434b to the mounting base 414a. In this design, the fiber holder 434c is rigid and fixedly secured the optical fiber 434b to the mounting base 414a and the other components of the laser assembly.

[00173] As an overview, in the implementation of Figures 4A and 4B, the coupling lens assembly 432 can include a coupling lens 432a (e.g., similar to the coupling lens described above) that focuses the output beam 12 onto the lens focal point, a rigid lens holder 432b that retains the coupling lens 432a, and a lens pointer adjuster 432c that can be used to intermittently or continuously adjust the pointing of the output beam 12 onto the fiber inlet facet 434a. It should be noted that the lens pointer adjuster 432c can also be referred to as a pointer adjuster assembly or a lens pointer adjuster assembly. As provided herein, the coupling lens assembly 432 can be used in the laser assembly 10 of Figure 1 , or another type of laser, in conjunction with or without the wedged window based pointer adjuster assembly 28 illustrated in Figure 1. [00174] Further, in Figures 4A and 4B, the lens pointer adjuster 432c includes an adjuster frame 432ca, and a lens actuator assembly 432cb that connects and couples the coupling lens assembly 432 to the optical fiber assembly 434. Alternatively, the lens pointer adjuster 432c can be designed to connect the coupling lens 432a directly to the mounting base 414a.

[00175] Additionally, or alternatively, the lens pointer adjuster 432c can include one or more position sensor(s) 432cc that provide feedback regarding position of coupling lens 432a for closed loop positional control using the system controller 36 (illustrated in Figure 1).

[00176] In the non-exclusive example illustrated in Figures 4A and 4B, (i) the adjuster frame 432ca is rigid and has an “L” shaped configuration, and (ii) the lens actuator assembly 432cb can include one or more actuators that are controlled by the system controller 36 (illustrated in Figure 1 ) to move and position the adjuster frame 432ca and the coupling lens 432a relative to the optical fiber assembly 434.

[00177] In this design, the lens actuator assembly 432cb is designed and controlled to provide relative movement between the coupling lens 432a and the fiber inlet facet 434a until the output beam 12 is properly focused on the fiber inlet facet 434a. With this design, for example, the power output in the optical fiber assembly 434 can be continuously or intermittently monitored, and the system controller 36 (using feedback regarding power output) can selectively control the lens actuator assembly 432cb to actively maintain the desired relative position between the coupling lens 432a and the fiber inlet facet 434a to maintain the maximum power output.

[00178] For example, the lens actuator assembly 432cb can be designed and controlled to move and position the coupling lens 432a relative to the fiber inlet facet 434a about and/or along one or axes. In one specific example, the lens actuator assembly 432cb can be designed and controlled to move and position the coupling lens 432a along the N and P axes to move the output beam 12 relative to the fiber inlet facet 434a. In a specific example, the lens actuator assembly 432cb can be designed and controlled to move and position the coupling lens 432a relative to the fiber inlet facet 434a along the N, O, and P axes. In this design, movement along the O axis adjusts the location of the lens focal point. As non-exclusive examples, the lens actuator assembly 432cb can include one or more actuators, motors, voice coil motors, piezoelectric actuators, shear piezos, thermal actuators, or other type of movers. [00179] Figure 5 is a side view of a portion of the mounting base 514a, and an alternative implementation of the coupling lens assembly 532, and the optical fiber assembly 534.

[00180] Similar to Figures 4A and 4B, Figure 5 includes the orientation system is referenced to the coupling lens assembly 532, and includes the N axis, the O axis, and the P axis.

[00181] In the non-exclusive example of Figure 5, the coupling lens assembly 532 can include a coupling lens 532a (e.g., similar to the coupling lens described above) that focuses the output beam 12 at a lens focal point, and a rigid lens holder 532b that retains the coupling lens 532a. In this design, the lens holder 532b includes a holder base 532ba that fixedly secures the lens holder 532b and the lens 532a to the mounting base 514a.

[00182] As an overview, in the implementation of Figure 5, the optical fiber assembly 534 additionally includes a fiber pointer adjuster 534d that can be used to intermittently or continuously adjust the position of the fiber inlet facet 534a of the optical fiber 534b, and the fiber holder 534c relative to the coupling lens 532a and the output beam 12. It should be noted that the fiber pointer adjuster 534d can also be referred to as the pointer adjuster assembly, or a fiber pointer adjuster assembly. As provided herein, the fiber pointer adjuster 534d can be used in the laser assembly 10 of Figure 1 , or another type of laser, in conjunction with or without the wedged window pointer adjuster assembly 28 (illustrated in Figure 1 ) and/or the lens pointer adjuster 432c (illustrated in Figures 4A and 4B).

[00183] Further, in Figure 5, the fiber pointer adjuster 534d can include an actuator assembly 534da that connects and couples the optical fiber assembly 534 to the coupling lens assembly 532. Alternatively, the fiber pointer adjuster 534d can be designed to connect the fiber holder 532b to the mounting base 514a.

[00184] Additionally, or alternatively, the fiber pointer adjuster 534d can include one or more position sensor(s) 534db (illustrated as a box) that provides feedback regarding position of fiber inlet facet 534a for closed loop positional control using the system controller 36 (illustrated in Figure 1 ).

[00185] In this design, the fiber pointer adjuster 534d is designed and controlled to provide relative movement between the fiber inlet facet 534a and the coupling lens 532a until the output beam 12 is properly focused on the fiber inlet facet 534a. With this design, for example, the power output in the optical fiber assembly 534 can be continuously or intermittently monitored, and the system controller 36 (using feedback regarding power output) can selectively control the fiber pointer adjuster 534d to actively maintain the desired relative position between the coupling lens 532a and the fiber inlet facet 534a to maintain the maximum power output.

[00186] For example, the fiber pointer adjuster 534d can be designed and controlled to move and position the fiber inlet facet 534a relative to the coupling lens 532a about and/or along one or axes. In one specific example, the fiber pointer adjuster 534d can be designed and controlled to move and position the fiber inlet facet 534a along the N and P axes. In a specific example, the fiber pointer adjuster 534d can be designed and controlled to move and position the fiber inlet facet 534a along the N, O, and P axes. As non-exclusive examples, the fiber pointer adjuster 534d can include one or more actuators, motors, voice coil motors, piezoelectric actuators, shear piezos, thermal actuators, or other type of movers.

[00187] Figure 6A is a simplified top view of a portion of a laser assembly 610 including (i) a mounting base 614a, (ii) an emitter 616, (iii) an emitter lens 618, (iv) a transmission grating assembly 620 including a transmission grating 620a having a periodic structure (not shown) that is aligned along a grating axis 620b, (v) a redirector assembly 622, and (vi) a system controller 636 that can be used in the laser assembly 10 of Figure 1 or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In this implementation, the mounting base 614a, the emitter 616, the emitter lens 618, the transmission grating 620a, the redirector assembly 622, and the system controller 636 can be somewhat similar to the corresponding components described above and illustrated in Figure 1.

[00188] Figure 6A includes an orientation system referenced to the transmission grating 620a that has a K axis, an L axis that is orthogonal to the K axis, and an M axis that is orthogonal to the K and L axes, and parallel to the grating axis 620b. It should be noted that these axes can also be referred to as the first, second and third axes.

[00189] As an overview, as provided herein, the transmission grating 620a can be selectively moved along the grating axis 620b to improve the performance of the laser assembly. In the non-exclusive implementation of Figure 6A, the transmission grating assembly 620 includes a grating mover assembly 620c that selectively moves the transmission grating 620a along a grating movement axis 620d (illustrated with a double headed arrow) that is substantially parallel to the grating axis 620a. [00190] Typically, the emitter 616 will produce gain over a substantial bandwidth. However, in the external laser cavity design of Figure 6A, the transmission grating 620a and the redirector assembly 622 will significantly narrow the range of effective gain for the emitter 616. More specifically, in this design, the transmission grating 620a and the redirector assembly 622 introduce a gaussian shaped filter to the effective gain of the emitter 616. This can be referred to as the “filter function”. The width of the filter function depends on the number of lines of the transmission grating 620a illuminated by the emitter 616, which is given by the line density of the grating, the angle of incidence, and the width of the emitter beam.

[00191] With the present design, the emitter 616 will ultimately only lase at one of its longitudinal modes. In general, due to mode competition, only the longitudinal mode which is closest to the center of the filter function will have the highest gain, and the emitter 616 will lase at that longitudinal mode.

[00192] In one implementation, the goal of mode hop free tuning is to move the filter function and the longitudinal modes at the same rate. By choosing an appropriate pivot point (not shown in Figure 6A) for the redirector 646, the angles of the cavity and the total length of the cavity can be concurrently adjusted to achieve mode hop free tuning. If the pivot point is imperfect, the longitudinal mode and the filter function will shift at different rates. Eventually, the lasing mode will move far away from the center of the filter function, while the next longitudinal mode shifts closer to the center. Eventually, this will result in a mode hop, where the lasing in the original longitudinal mode ceases, and lasing begins instead in the higher gain mode which is closer to the center of the filter function.

[00193] It should be noted that while lasing will generally occur only for the longitudinal mode which has the highest gain (i.e. the one closest to the center of the filter function), this mode will not in general, be exactly centered on the filter function. As a result thereof, output power will not be optimized. In order to optimize or maximize power, the present design provides a way to shift the longitudinal modes of the emitter 616 without changing the filter function. More specifically, moving the transmission grating 620a along the grating axis 620b (parallel to its face and perpendicular to the axis of the lines) is one way to shift the longitudinal modes of the emitter 616 relative to the filter function. Generally, a movement of < should be required to center the longitudinal mode on the filter function and optimize lasing. [00194] As provided herein, the grating mover assembly 620c selectively moves the transmission grating 620a along the grating axis 620b (referred to as “shear motion”) to selectively adjust the longitudinal mode without shifting the filter function. In this design, the grating mover assembly 620c can be controlled to selectively move the transmission grating 620a along the grating axis 620b to selectively position the desired longitudinal mode to the center of the filter function. This will improve the output power of the emitter 616.

[00195] In one implementation, the grating mover assembly 620c can selectively move the transmission grating 620a along the grating axis 620b to reduce modulation of the optical power of the first beam while tuning of the wavelength of the emitter 616.

[00196] It should be noted that the laser assembly 610 design of Figure 6A, a primary laser cavity extends from the rear, second facet 616d of the emitter 616 to the reflective surface of the redirector 646. The primary laser cavity can alternatively be referred to as a “primary cavity”, an “intended cavity” or a “desired cavity”.

[00197] Unfortunately, the anti-reflective coatings on the components in the external, primary cavity are not one hundred percent perfect. For example, the anti- reflective coating on the front, first facet 616c of the emitter 616 is not perfect. As a result thereof, during operation of the laser assembly 610, (i) a first (long) parasitic laser cavity may also be formed between the front, first facet 616c and the redirector 646; and (ii) a second (short) parasitic laser cavity can be formed between the front, first facet 616c and the rear, second facet 616d of emitter 616. Each parasitic laser cavity can alternatively be referred to as a “parasitic cavity”, an “unintended cavity”, or an “undesired cavity”.

[00198] The primary cavity has a primary cavity optical length, a primary free spectral range (primary FSR), and light (referred herein to as “primary light”) will be lasing at a primary center wavelength that corresponds to the primary cavity optical length. Somewhat similarly, the first parasitic cavity has a first parasitic cavity optical length and a first parasitic free spectral range (first parasitic FSR) that corresponds to the first parasitic cavity optical length. Further, the second parasitic cavity has a second parasitic cavity optical length, and a second parasitic free spectral range (second parasitic FSR) that corresponds to the second parasitic cavity optical length. The second parasitic laser cavity is very short, and will have a larger free spectral range (FSR). As a result thereof, the second parasitic cavity typically has only a slight impact on the performance of the laser assembly. [00199] As provided herein, the primary cavity optical length is close in length to, but different from the first parasitic cavity optical length. In the non-exclusive example of Figure 6A, the primary cavity optical length is longer than the parasitic cavity optical length, and the difference is equal to the optical length of the emitter 616. As a result of the difference in optical cavity lengths, the primary FSR will be slightly shorter than second parasitic FSR. This can result in the attenuation of the primary light, and can introduce undulations to the otherwise gaussian filter function of the cavity (with a period given by the first parasitic cavity FSR). This will affect the amplitude of the lasing mode, and can also introduce unwanted effects during tuning.

[00200] Typically, the anti-reflective coatings on the front, first facet 616c is very good. As a result, very little light is reflected, and the optical power of the parasitic light is very small when compared to the optical power of the primary light. Unfortunately, even a very small amount of the first parasitic light can interfere with the primary light and adversely influence the optical power of the output beam 12. The present invention provides a way to reduce the influence of the first parasitic light on the optical power of the output beam 12.

[00201] As provided herein, when performing a shear motion of the transmission grating 620a, the filter function will not move, the longitudinal modes will move, and the parasitic undulation will move as well, but not at the same rate.

[00202] As provided herein, the role of the grating shear movement is to optimize the intensity of the lasing mode by moving it around on the filter function. In the absence of parasitic undulations, this means moving it to the center of the gaussian filter function which is very straightforward. In the presence of the parasitic cavity, this optimization becomes less straightforward. As provided herein, in certain implementations, the grating 620a is moved in shear motion (as necessary) during wavelength tuning to optimize the output power at each target wavelength.

[00203] In summary, the transmission grating 620a can be selectively moved along the grating movement axis 620d to achieve the desired power (e.g., maximize) of the output beam 12. In certain designs, the transmission grating 620a can be selectively moved along the grating movement axis 620d while the redirector 646 is selectively moved, to inhibit (minimize) the modulation of the optical power of the output beam 12 while tuning. This will result in the output beam 12 having a substantially constant optical power while the laser assembly 610 is tuned over its desired spectral range. [00204] In a specific, non-exclusive implementation, the transmission grating 620a is a volume phase holograph grating. However, other transmission gratings can be utilized.

[00205] The design and movement achieved by the grating mover assembly 620c can be varied to suit the design of the transmission grating 620a. For example, the grating mover assembly 620c can include one or more linear actuators that selectively move the transmission grating 620a along the grating movement axis 620d. As a specific example, the grating mover assembly 620c can include one or more shear piezoelectric actuators, linear motors, thermal movers or type of actuators.

[00206] In this design, the grating mover assembly 620c can be controlled by the system controller 636 to precisely move and position the transmission grating 620a relative to the mounting base 614a, the emitter 616, the emitter lens 618, and the redirector 646. As provided herein, in certain designs, the transmission grating 620a can be precisely moved to selectively adjust and tune the parasitic wave period and the primary wave period.

[00207] Stated differently, the grating mover assembly 620c can selectively move the transmission grating 620a along the grating axis 620b to maximize the optical power of the output beam 12. Thus, the present design provides for the active adjustment of the longitudinal mode relative to the filter function.

[00208] With the present design, the system controller 636 can continuously receive feedback from the feedback system 52 (illustrated in Figure 1) regarding the optical power of the output beam 12. For example, with this information, during tuning of the laser assembly 610, the system controller 636 can control the grating mover assembly 620c to quickly position the transmission grating 620a along the grating axis 620b to maximize the optical power of the output beam 12, and/or inhibit the modulation of the optical power of the output beam 12. Alternatively, for example, during tuning, the system controller 636 can use a lookup table to control the grating mover assembly 620c to quickly position the transmission grating 620a along the grating axis 620b to maximize the optical power of the output beam 12, and/or inhibit the modulation of the optical power of the output beam 12.

[00209] With this design, the grating mover assembly 620c can quickly position the transmission grating 620a along the grating axis 620b.

[00210] Additionally, and optionally, the transmission grating assembly 620 can include a grating position sensor 620e (illustrated as a box) the provides the feedback regarding the position of the transmission grating 620a to the system controller 36 for closed loop control.

[00211] Figures 6B, 6C, and 6D are simplified side views that illustrate the transmission grating 620a, the grating mover assembly 620c, and the mounting base 614a at different times. In this design, the grating mover assembly 620c selectively moves the transmission grating 620a along the grating movement axis 620d that is substantially parallel to the grating axis 620b.

[00212] Figures 6B-6D also include the orientation system that is referenced to the transmission grating 620a, and includes the K axis, the L axis, and the M axis.

[00213] Figure 6B illustrates the transmission grating 620a, the grating mover assembly 620c, and the mounting base 614a at a first time, when the grating mover assembly 620c has positioned the transmission grating 620a at a nominal position relative to the mounting base 614a along the grating movement axis 620d.

[00214] Figure 6C illustrates the transmission grating 620a, the grating mover assembly 620c, and the mounting base 614a at a second time, when the grating mover assembly 620c has moved and positioned the transmission grating 620a at a leftmost “negative” position relative to the mounting base 614a along the grating movement axis 620d.

[00215] Figure 6D illustrates the transmission grating 620a, the grating mover assembly 620c, and the mounting base 614a at a third time, when the grating mover assembly 620c has moved and positioned the transmission grating 620a at a rightmost “positive” position relative to the mounting base 614a along the grating movement axis 620d.

[00216] With reference to Figures 6A-6D, with the present design, the transmission grating 620a can be precisely moved and positioned by the grating mover assembly 620c along the grating axis 620b relative to the other components of the laser assembly 610 and the emitter beam 16a (illustrated in Figure 1 ) to selectively adjust the output power.

[00217] Figure 7A is a simplified top view of a portion of a laser assembly 710 including (i) a mounting base 714a, (ii) an emitter 716, (iii) an emitter lens 718, (iv) a transmission grating assembly 720 including a transmission grating 720a having a periodic structure (not shown) that is aligned along a grating axis 720b and a grating mover assembly 720c, (v) a redirector assembly 722, and (vi) a system controller 736 that can be used in the laser assembly 10 of Figure 1 or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1). In this implementation, the mounting base 714a, the emitter 716, the emitter lens 718, the transmission grating 720a, the redirector assembly 722, and the system controller 736 can be somewhat similar to the corresponding components described above and illustrated in Figure 1.

[00218] Figure 7 A includes the orientation system referenced to the transmission grating assembly 720 that includes the K axis, the L axis, and the M axis.

[00219] In this design, the transmission grating 720a has a grating transverse axis 720f (illustrated as circle) that is parallel to the K axis and normal to the grating axis 720b. As provided herein, with the implementation illustrated in Figure 7A, the transmission grating 720a can be moved (e.g., rotated) about the grating transverse axis 720f (yaw movement) without adversely influencing the pointing direction of the first beam 740 along the first beam axis 740a, and the pointing direction of the second beam 742 along the second beam axis 742a. Stated differently, movement of the transmission grating 720a about the grating transverse axis 720f will not changing the pointing direction of the output beam 12 (illustrated in Figure 1) so the output beam 12 will remain fiber coupled; and will not change pointing direction of the second beam 742 so the primary laser cavity will remain stable.

[00220] As provided herein, movement of the transmission grating 720a about the grating transverse axis 720f can be referred to as yaw movement 720g (illustrated with an arch shaped, double sided, arrow). It should be noted that in the implementation of Figure 7A, the transmission grating 720a (i) is illustrated in solid lines in a first yaw position, (ii) is illustrated in short-dashed lines in a second yaw position, and (iii) is illustrated in dotted lines in a third yaw position. In this design, rotation of the transmission grating 720a about the yaw direction will not change the pointing direction but will slightly displace the beam.

[00221] Further, with the cavity design of Figure 7A, there is a steep angle of incidence 721 of the emitter beam 716a relative face of the transmission grating 720a and the grating axis 720b. Because of this steep angle of incidence 721 , any yaw movement of the transmission grating 720a will result in only a minor change in wavelength of the output beam. In one example, there is zero change in wavelength at the Littrow angle of incidence.

[00222] In summary, as a result of the cavity design provided herein, the laser assembly 710 is insensitive to yaw movements of the transmission grating 720a between the yaw positions, and the laser assembly 710 is more stable. [00223] In Figure 7A, in the first yaw position of the transmission grating 720a, (i) the first beam 740 is directed parallel to and along the first beam axis 740a; and (ii) the second beam 742 is directed parallel to and along the second beam axis 742a.

[00224] Figure 7B illustrates the portion of the laser assembly 710 from Figure 7A, including (i) the mounting base 714a, (ii) the emitter 716, (iii) the emitter lens 718, (iv) the transmission grating assembly 720 including the transmission grating 720a, and the grating mover assembly 720c, (v) the redirector assembly 722, and (vi) the system controller 736 that can be used in the laser assembly 10 of Figure 1 or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1). In this implementation, the mounting base 714a, the emitter 716, the emitter lens 718, the transmission grating 720a, the redirector assembly 722, and the system controller 736 can be somewhat similar to the corresponding components described above and illustrated in Figure 7A.

[00225] Figure 7B includes the orientation system referenced to the transmission grating assembly 720 that includes the K axis, the L axis, and the M axis.

[00226] As provided above, the transmission grating 720a can be rotated about the grating transverse axis 720f (illustrated as circle) without adversely influencing the pointing direction of the first beam 740 along the first beam axis 740a, and the pointing direction of the second beam 742 along the second beam axis 742a.

[00227] It should be noted that in Figure 7B (and in contrast to Figure 7A), the transmission grating 720a (i) is illustrated in short-dashed lines in the first yaw position, and (ii) is illustrated in solid lines in a second yaw position, to highlight that the transmission grating 720a has been moved from the first yaw position to the second yaw position.

[00228] In Figure 7B, in the second yaw position of the transmission grating 720a, (i) the first beam 740 is directed parallel to and slightly offset from the first beam axis 740a; and (ii) the second beam 742 is directed parallel to and slightly offset from the second beam axis 742a.

[00229] It should be noted that movement of the transmission grating 720a about grating transverse axis 720f changes the angle of incidence 721 (illustrated in Figure 7A) of the emitter beam 716a on the face of the transmission grating 720a. As provided herein, with certain designs, the transmission grating 720a is designed so that a change in the angle of incidence changes the effective reflectivity of the primary external cavity, via the change in power refracted into the different orders (0, 1 ) of the transmission grating 720a and the values of the first beam 740 and the second beam 742. With this design, the transmission grating 720a can be selectively rotated about the grating transverse axis 720f to selectively change amount of light refracted in each order to achieve the desired ratio of the first beam 740 and the second beam 742. Stated differently, the transmission grating 720a can be selectively rotated about the grating transverse axis 720f to selectively change the ratio of orders (e.g., 0,1). For example, transmission grating 720a can be selectively rotated about the grating transverse axis 720f to achieve the desired balance between the beams 740, 742, and achieve maximum optical power of the optical beam 12.

[00230] Similarly, Figure 7C illustrates the portion of the laser assembly 710 from Figure 7A, including (i) the mounting base 714a, (ii) the emitter 716, (iii) the emitter lens 718, (iv) the transmission grating assembly 720 including the transmission grating 720a, and the grating mover assembly 720c, (v) the redirector assembly 722, and (vi) the system controller 736 that can be used in the laser assembly 10 of Figure 1 or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In this implementation, the mounting base 714a, the emitter 716, the emitter lens 718, the transmission grating 720a, the redirector assembly 722, and the system controller 736 can be somewhat similar to the corresponding components described above and illustrated in Figure 7A.

[00231] Figure 7C includes the orientation system referenced to the transmission grating assembly 720 that includes the K axis, the L axis, and the M axis.

[00232] It should be noted that in Figure 7C (and in contrast to Figure 7A), the transmission grating 720a (i) is illustrated in dashed in the first yaw position, and (ii) is illustrated in solid lines in a third yaw position, to highlight that the transmission grating 720a has been moved from the first yaw position to the third yaw position.

[00233] In Figure 7C, in the third yaw position of the transmission grating 720a, (i) the first beam 740 is directed parallel to and slightly offset from the first beam axis 740a; and (ii) the second beam 742 is directed parallel to and slightly offset from the second beam axis 742a.

[00234] As provided above, movement of the transmission grating 720a about grating transverse axis 720f changes the angle of incidence 721 (illustrated in Figure 7A) of the emitter beam 716a on the face of the transmission grating 720a. Further, with certain designs, of the transmission grating 720a is designed so that a change in the angle of incidence 721 changes the effective reflectivity of the transmission grating 720a, changes the diffraction experienced by the emitter beam 716a, and the values of the first beam 740 and the second beam 742.

[00235] With reference to Figures 7A-7C, in one implementation, (i) movement of the transmission grating 720a about grating transverse axis 720f in the one direction (e.g., clockwise) increases the optical power of the second beam 742, and decreases the optical power of the first beam 740; and (ii) movement of the transmission grating 720a about grating transverse axis 720f in the opposite direction (e.g., counterclockwise) decreases the optical power of the second beam 742, and increases the optical power of the first beam 740. Stated differently, (i) movement of the transmission grating 720a about grating transverse axis 720f in the clockwise direction increases the amount of the emitter beam 716a that is diffracted into the second beam 742, and decreases the amount of the emitter beam 716a that is diffracted into the first beam 740; and (ii) movement of the transmission grating 720a about the grating transverse axis 720f in the counter-clockwise direction decreases the amount of the emitter beam 716a that is diffracted into the second beam 742, and increases the amount of the emitter beam 716a that is diffracted into the first beam 740.

[00236] With this design, the transmission grating 720a can be selectively moved in yaw in order to achieve the desired balance (percentage of each) between the first beam 740 and the second beam 742 balance to achieve maximum optical power of the output beam 12. Stated differently, with this design, the transmission grating 720a can be selectively rotated about the grating transverse axis 720f to selectively change the amount (percent) of light refracted in each order to achieve the desired ratio of the first beam 740 and the second beam 742.

[00237] It should be noted that a Rigrod analysis can be used to determine the theoretical rotational position of the transmission grating 720a about the grating transverse axis 720f. Subsequently, the rotational position of the transmission grating 720a about the grating transverse axis 720f can be adjusted during assembly and testing of the laser assembly 710, and subsequently fixed. Alternatively, for example, the grating mover assembly 720c can be designed to selectively rotate the transmission grating 720a about the grating transverse axis 720f .

[00238] In one non-exclusive example, the transmission grating 720a has a refractance that varies depending on the angle of incidence 721. As non-exclusive examples, the transmission grating 720a is a volume phase holographic grating having unequal diffraction efficiencies. [00239] The present invention provides that if a diffraction grating 720a (can be transmissive or reflective) has a diffraction efficiency which is dependent on the angle of incidence, then in it will be possible to tune the feedback of the emitter 716 by adjusting that angle of incidence through the “yaw” of the grating 720a. For a transmission grating 720a, changing the angle of incidence will in general change the balance of diffraction efficiency in the transmitted and diffracted order. Typically if the zero order transmission efficiency (effectively our “output coupler”) increases, the -1 order diffracted efficiency (effectively the square root of our feedback) decreases and vice versa. For any given emitter 716, there is some optimal ratio of feedback and output coupling that will provide the most output power from the cavity.

[00240] As provided herein, the yaw movement discussed herein is particularly useful for gratings 720a having a diffraction efficiency which is strongly dependent on the angle of incidence to enable this optimization. As used herein, strongly dependent means “a five degree change in yaw will result is at least a five percent change in diffraction efficiency”.

[00241] Figure 8 is another, simplified top view of a portion of a laser assembly 810 including (i) a mounting base 814a, (ii) an emitter 816 generating an emitter beam 816a, (iii) an emitter lens 818, (iv) a transmission grating assembly 820 including a transmission grating 820a, (v) a redirector assembly 822 including a redirector 846 and a redirector mover 848 (illustrated as a box), and (vi) a system controller 836 that can be used in the laser assembly 10 of Figure 1 or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In this implementation, the mounting base 814a, the emitter 816, the emitter lens 818, the transmission grating assembly 820, the redirector assembly 822, and the system controller 836 can be somewhat similar to the corresponding components described above in any of the embodiments.

[00242] Figure 8 includes the orientation system referenced to the transmission laser assembly 810 that includes the X axis, the Y axis, and the Z axis.

[00243] In one implementation, as provided herein, the redirector mover 848 selectively moves the redirector 846 approximately about a selected pivot axis 854 (illustrated with a plus sign) during tuning of the primary laser cavity, and tuning of the primary center wavelength of the emitter beam 816a, and the first beam 840. Stated in a different fashion, the redirector mover 848 selectively moves the redirector 846 approximately about the selected pivot axis 854 during the selective adjustment of the optical path length of the primary laser cavity.

[00244] As provided herein, in the event that the selected pivot axis 854 is correctly determined, and the redirector mover 848 is designed to accurately pivot the redirector 846 about the selected pivot axis 854; then the laser assembly 810 can be accurately tuned over a relatively large, desired spectral range without mode hops. As alternative, non-exclusive examples, the laser assembly 810 can be designed to be accurately tuned over a desired, spectral range of at least approximately forty, fifty, sixty, seventy, eighty, ninety, one hundred, or more gigahertz without mode hops.

[00245] It should be noted that an analysis of the design and geometry of the components of the laser assembly 810 can be used to determine a theoretical pivot axis 855 (illustrated as a circle) for the redirector 846 that will achieve mode hop free tuning over the desired spectral range. Unfortunately, manufacturing and assembly of the components of the laser assembly 810 is never perfect and/or the components will shift during temperature and/or vibration cycling. As a result thereof, the theoretical pivot axis 855 may not be the axis which will achieve mode hop free tuning for the laser assembly 810 over a large spectral range. In the simplified example of Figure 8, the selected pivot axis 854 is illustrated as being offset from the theoretical pivot axis 855.

[00246] In one implementation, the theoretical pivot axis 855 is utilized as a starting place for determining the selected pivot axis 854 of the redirector 846. In one specific example, after the laser assembly 810 is temperature and/or vibration cycled, and ready for final alignment, a redirector holder 856 (e.g., a robotic arm or other mechanism) can retain and position the redirector assembly 822 at the theoretical pivot axis 855. At this time, the laser assembly 810 can be operated and tuned over the desired spectral range by pivoting the redirector 846, and monitoring the output beam 12 (illustrated in Figure 1). If there are no mode hops during this tuning, the redirector assembly 822 can be fixedly secured to the mounting base 814a.

[00247] Alternatively, if there are one or more mode hop(s) during tuning over the desired spectral range, the redirector holder 856 can slightly adjust the position of the redirector assembly 822, and the laser assembly 810 can be tuned over the desired spectral range, while monitoring the output beam 12 for mode hops. This testing process can be repeated until the redirector assembly 822 is positioned at the location in which the laser assembly 810 can be tuned over the desired spectral range, without mode hops. This location is the selected pivot axis 854. At this time, the redirector assembly 822 can be fixedly secured to the mounting base 814a.

[00248] It should be noted that the procedure discussed in reference to Figure 8 for properly positioning the redirector mover 848 can be used in any of the designs disclosed herein.

[00249] Figure 9A is a simplified top view of a portion of a laser assembly 910 including (i) a portion of a laser frame 914, and (ii) a redirector assembly 922 that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In this implementation, the laser frame 914 and the redirector assembly 922 can be somewhat similar to the corresponding components described above.

[00250] Figure 9A also includes the orientation system referenced to the transmission laser assembly 910 that includes the X axis, the Y axis, and the Z axis.

[00251] As an overview, in this implementation, the laser assembly 910 includes a unique guide fastener 958 (i) that allows for the relatively easy movement and adjustment of the redirector assembly 922 during location of the selected pivot axis 954A (illustrated with a plus sign), and (ii) that subsequently fixedly attaches the redirector assembly 922 to the laser frame 914.

[00252] In the non-exclusive implementation of Figure 9A, the laser frame 914 includes the rigid mounting base 914a, and a rigid, transverse mounting frame 914aa that extends upward, orthogonal to the mounting base 914a. In this design, the redirector assembly 922 is fixedly secured to the mounting frame 914aa. It should be noted that other designs of the laser frame 914 are possible.

[00253] The redirector assembly 922 receives the second beam 42 (illustrated in Figure 1) from the transmission grating 20a (illustrated in Figure 1 ) and redirects the second beam 42 back to the transmission grating 20a. A number of non-exclusive designs of the redirector assembly 922 are provided herein. In each design, the redirector assembly 922 is designed to allow for almost pure rotation about the selected pivot axis 954A, with very little parasitic shift. Further, in certain designs, the redirector assembly 922 has a relatively small form factor.

[00254] In the non-exclusive implementation of Figure 9A, the redirector assembly 922 includes a redirector 946, and a redirector mover 948 that selectively moves the redirector 946 about the selected pivot axis 954A. In this design, the redirector 946 can include a retroreflector such as a porro prism. [00255] In the non-exclusive implementation of Figure 9A, the redirector mover 948 includes a redirector actuator assembly 948a, and a guide assembly 948b that accurately guides the movement of the redirector 946. As provided herein, the redirector actuator assembly 948a is controlled by the system controller 36 (illustrated in Figure 1) to precisely move the redirector 946 to precisely adjust the optical path length of the primary external cavity. As non-exclusive examples, the redirector actuator assembly 948a can include one or more (i) piezoelectric actuator(s), such as shear piezos (e.g., bidirectional, passive or active running), and/or piezo clips; (ii) bimetallic strip(s); (iii) thermoelectric cooler(s); (iv) heater(s), (v) voice coil(s), (vi) stepper motor(s), (vii) solenoid(s), (viii) electrostriction, (ix) motor(s), and/or (x) actuator(s).

[00256] As non-exclusive examples, the guide assembly 948b can include one or more (i) flexure(s); (ii) bearing(s); and/or (iii) other rotary guide(s). In the simplified example of Figure 9A, the guide assembly 948b is generally “U” shaped flexure, and includes (i) a first guide side 948ba that is secured to the mounting frame 914aa; (ii) a second guide side 948bb that is spaced apart from the first guide side 948ba; and (iii) a guide connector 948bc that connects the guide sides 948ba, 948bb. In certain designs, the flexure 948b is relatively stiff. Further, in Figure 9A, the redirector 946 is fixedly secured to the second guide side 948bb.

[00257] It should be noted that the folded cavity of the laser assembly 10 (illustrated in Figure 1 ) reduces vibration sensitivity of laser frequency by a stiffer flexure 948b. Further, this folded cavity results in a more compact arrangement.

[00258] In the design of Figure 9A, the redirector actuator assembly 948a extends between the guide sides 948ba, 948bb, and the redirector actuator assembly 948a moves the second guide side 948bb (with the redirector 946) relative to the first guide side 948ba while deflecting the guide connector 948bc. This design allows for the accurate movement of the redirector 946 about the selected pivot axis 954A.

[00259] Figure 9A also illustrates the theoretical pivot axis 955 (illustrated as a circle) for the redirector 946. As provided above, the selected pivot axis 954A that will achieve mode hop free tuning over the desired spectral range, may be offset from the theoretical pivot axis 955. As described above, after the laser assembly 910 is temperature and/or vibration cycled, and ready forfinal alignment, the redirector holder 856 (illustrated in Figure 8) can retain and hold in position the redirector assembly 922 at the theoretical pivot axis 955. At this time, the laser assembly 910 can be tuned over the desired spectral range by pivoting the redirector 946 with the redirector mover 948, and monitoring the output beam 12 (illustrated in Figure 1 ). If there are no mode hops during this tuning, the redirector assembly 922 can be fixedly secured to the mounting frame 914aa.

[00260] Alternatively, if there are one or more mode hop(s) during tuning over the desired spectral range, the redirector holder 856 (illustrated in Figure 8) can slightly adjust the position of the redirector assembly 922, and the process can be repeated. This testing process can be repeated until the selected pivot axis 954A is determined. At this time, the redirector assembly 922 can be fixedly secured to the mounting base 814a.

[00261] As provided above, the guide fastener 958 (i) allows for the relatively easy movement and adjustment of the redirector assembly 922 during location of the selected pivot axis 954A, and (ii) subsequently fixedly securing the first guide side 948ba to the mounting frame 914aa. In one non-exclusive example, the guide fastener 958 is an adhesive puddle that extends between the mounting frame 914aa and the first guide side 948ba. Alternatively, or additionally, the guide fastener 958 can include one or more welds, solders, or fasteners.

[00262] With the present design, the redirector assembly 922 can be easily moved about and/or along one or more axes relative to the mounting frame 914aa and the theoretical pivot axis 955, to locate the selected pivot axis 954A. As a nonexclusive example, the guide fastener 958 allows for the redirector assembly 922 to be easily moved along the Y axis, along the X axis, and/or about the Z axis relative to the mounting frame 914aa to locate the selected pivot axis 954A. Alternatively, the guide fastener 958 can allow for movement of the redirector assembly 922 with less than three, or more than three degrees of freedom to locate the selected pivot axis 954A. In the design of Figure 9A, the guide fastener 958 can allow for movement of the redirector assembly 922 with six degrees of freedom.

[00263] Subsequently, after the redirector assembly 922 is properly positioned at the selected pivot axis 954A, the adhesive puddle 958 can be added and cured to fixedly secure the redirector assembly 922 to the laser frame 914.

[00264] A number of alternative designs of the guide assembly 948b that guides movement of the redirector 946 about the selected pivot axis 954A are provided herein. In certain designs, the guide assembly 948b allows for accurate movement about the selected pivot axis 954A, while inhibiting movement about the other degrees of freedom to minimize any parasitic shift of the redirector 946. As provided herein, sufficient parasitic shift can induce mode hops while tuning over the desired spectral range. In Figure 9A, the selected pivot axis 954b is parallel to the Z axis. In this design, the guide assembly 948b allows for accurate movement of the redirector 946 about the Z axis, while inhibiting movement about X and Y axes, and along X, Y and Z axes.

[00265] In certain designs, the guide assembly 948b is designed to be (i) relatively flexible (low stiffness) in one degree of freedom (e.g., about the selected pivot axis 954A), and (ii) relatively stiff (high stiffness) in the other five degrees of freedom (e.g., about X and Y axes, and along X, Y and Z axes).

[00266] The amount of movement (“required redirector movement”) of the redirector 946 required to tune the laser assembly 910 over the desired spectral range will depend on many factors, including the design of the laser cavity, and the desired spectral range. In alternative, non-exclusive designs, the required redirected movement is approximately 120, 140, 160,165, 170, 180, or 200 micro-radians rotation about the selected pivot axis 954a during tuning over the desired spectral range. However, other values are possible.

[00267] It should be noted that the guide assemblies 948b provided herein can achieve the required redirector movement, with very little parasitic shift. As alternative, non-exclusive examples, the guide assemblies 948b provided herein can have a parasitic shift of less than approximately 15, 20, 25, 30, 40, or 50 nanometers during the required redirector movement.

[00268] Figure 9B is a simplified top view of the portion of the laser assembly 910 from Figure 9A, including (i) the laser frame 914, and (ii) the redirector assembly 922. However, in Figure 9B, the redirector assembly 922 is positioned slightly differently relative to the laser frame 914 than the implementation of Figure 9A.

[00269] More specifically, as illustrated in Figure 9B, the located, selected pivot axis 954B in Figure 9B (determined by testing) is slightly different from the located, selected pivot axis 954A in Figure 9A. The theoretical pivot axis 955 is also illustrated in Figure 9B.

[00270] Figure 9B, illustrates that the unique guide fastener 958 (i) allows for the redirector assembly 922 to be easily moved and adjusted during location of the selected pivot axis 954B, and (ii) subsequently fixedly attaches the redirector assembly 922 to the laser frame 914. [00271] Figure 90 is a simplified top view of the portion of the laser assembly 910 from Figures 9A and 9B, including (i) the laser frame 914, and (ii) the redirector assembly 922. However, in Figure 90, the redirector assembly 922 is positioned slightly differently relative to the laser frame 914 than the implementation of Figures 9A and 9B.

[00272] More specifically, as illustrated in Figure 9C, the located, selected pivot axis 954C in Figure 90 (determined by testing) is slightly different from the located, selected pivot axis 954A in Figure 9A, and the selected pivot axis 954B in Figure 9B. The theoretical pivot axis 955 is also illustrated in Figure 9C.

[00273] Figure 9C, illustrates that the unique guide fastener 958 (i) allows for the redirector assembly 922 to be easily moved and adjusted during location of the selected pivot axis 9540, and (ii) subsequently fixedly attaches the redirector assembly 922 to the laser frame 914.

[00274] Figures 10A and 10B are simplified top views of another portion of the laser assembly 1010 at different times, that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In Figures 10A and 10B, the laser assembly 1010 includes (i) the mounting frame 1014aa of the laser frame 1014, (ii) the redirector actuator assembly 1048a and the guide assembly 1048b of the redirector assembly 1022, and (iii) a guide fastener 1058. In this implementation, these components can be somewhat similar to the corresponding components described above.

[00275] Figures 10A and 10B also include the orientation system referenced to the transmission laser assembly 1010 that includes the X axis, the Y axis, and the Z axis.

[00276] In the non-exclusive design of Figures 10A and 10B, the guide assembly 1048b is a generally “butterfly” shaped flexure, and includes (i) a first guide side 1048ba that is secured to the mounting frame 1014aa; (ii) a second guide side 1048bb that is spaced apart from the first guide side 1048ba; and (iii) a guide connector 1048bc that connects the guide sides 1048ba, 1048bb. In certain designs, the flexure 1048b is relatively stiff. Further, in Figure 10A, the redirector 946 (illustrated in Figure 9A) is fixedly secured to the second guide side 1048bb.

[00277] Comparing Figure 10B to Figure 10A, the redirector actuator assembly 1048a has expanded to deform the guide assembly 1048b. [00278] Figure 11 is a simplified top view of another portion of the laser assembly 11 10 that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In Figure

11 , the laser assembly 1110 includes (i) the mounting frame 1114aa of the laser frame 11 14, (ii) the redirector actuator assembly 1148a and the guide assembly 1148b of the redirector assembly 1122, and (iii) a guide fastener 1158. In this implementation, these components can be somewhat similar to the corresponding components described above.

[00279] In the non-exclusive design of Figure 11 , the guide assembly 1148b is a generally “T” shaped flexure, and includes (i) a first guide side 1148ba that is secured to the mounting frame 11 aa; (ii) a second guide side 1148bb that is spaced apart from the first guide side 1148ba; and (iii) a guide connector 1148bc that connects the guide sides 1148ba, 1148bb. Further, in this implementation, the redirector actuator assembly 1148a selectively applies a force to the second guide side 1 148bb to selectively deflect the guide assembly 1148b and move the second guide side 1148bb. In certain designs, the flexure 1 148b is relatively stiff. Further, in Figure 11 , the redirector 946 (illustrated in Figure 9A) can be fixedly secured to the second guide side 1148bb.

[00280] Figure 12 is a simplified top view of another portion of the laser assembly 1210 that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1). In Figure

12, the laser assembly 1210 includes (i) the mounting frame 1214aa of the laser frame 1214, (ii) the redirector actuator assembly 1248a and the guide assembly 1248b of the redirector assembly 1222, and (iii) a guide fastener 1258. In this implementation, these components can be somewhat similar to the corresponding components described above.

[00281] In the non-exclusive design of Figure 12, the guide assembly 1248b is a flexure, and includes (i) a first guide side 1248ba that is secured to the mounting frame 1214aa; (ii) a second guide side 1248bb that is spaced apart from the first guide side 1248ba; and (iii) a plurality of guide connectors 1248bc that connect the guide sides 1248ba, 1248bb. In this design, the guide connectors 1248bc are arranged in a six spoke cartwheel arrangement. Alternatively, the design can include more than six or fewer than six guide connectors 1248bc and/or the arrangement can be different than that illustrated in Figure 12. [00282] Further, in this implementation, the redirector actuator assembly 1248a selectively applies a force to the second guide side 1248bb to selectively deflect the guide assembly 1248b and move the second guide side 1248bb. In certain designs, the flexure 1248b is relatively stiff. Further, in Figure 12, the redirector 946 (illustrated in Figure 9A) can be fixedly secured to the second guide side 1248bb.

[00283] Figure 13A is a simplified top view of another portion of the laser assembly 1310 that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1 ). In Figure 13A, the laser assembly 1310 includes (i) the mounting frame 1314aa of the laser frame 1314, (ii) the redirector actuator assembly 1348a and the guide assembly 1348b of the redirector assembly 1322, and (iii) a guide fastener 1358. In this implementation, these components can be somewhat similar to the corresponding components described above.

[00284] In the non-exclusive design of Figure 13A, the guide assembly 1348b is a flexure, and includes (i) a first guide side 1348ba; (ii) a second guide side 1348bb; and (iii) a plurality of guide connectors 1348bc that similar to the design in Figure 12. However, the implementation of Figure 13A includes eight guide connectors 1348bc arranged in an eight spoke cartwheel arrangement. In this design, the guide connectors 1348bc have a large hub 1348bch that minimizes parasitic shift.

[00285] Figure 13B is a side view of the guide assembly 1348b of Figure 13A, and including (i) the first guide side 1348ba; (ii) the second guide side 1348bb; and (iii) the plurality of guide connectors 1348bc. Figure 13B also illustrates that the guide connectors 1348bc have a connector height 1349a, and a connector width 1349b that can be adjusted to achieve the desired characteristics of the guide assembly 1348b. For example, the ratio of the connector height 1349a, and the connector width 1349b can be adjusted to have a low stiffness about the selected pivot axis, and high stiffness in the other five degrees of freedom. This will result in accurate pivoting about the selected pivot axis, while inhibiting parasitic shifts in the other degrees of freedom.

[00286] Figure 14 is a simplified top view of another portion of the laser assembly 1410 that can be used in any of the laser assemblies provided herein, or another type of laser assembly for generating an output beam 12 (illustrated in Figure 1). In Figure 14, the laser assembly 1410 includes (i) the mounting frame 1414aa of the laser frame 1414, (ii) the redirector actuator assembly 1448a and the guide assembly 1448b of the redirector assembly 1422, and (iii) a guide fastener 1458. In this implementation, these components can be somewhat similar to the corresponding components described above.

[00287] In the non-exclusive design of Figure 14, the guide assembly 1448b is a flexure that is shaped somewhat in a rectangular pattern, and includes (i) a first guide side 1448ba that is secured to the mounting frame 1414aa; (ii) a second guide side 1448bb that is spaced apart from the first guide side 1448ba; and (iii) a pair of guide connectors 1448bc that connect the guide sides 1448ba, 1448bb. Further, in this implementation, the redirector actuator assembly 1448a selectively applies a force to one of the guide connectors 1448bc to selectively deflect the guide assembly 1448b and move the second guide side 1448bb. In certain designs, the flexure 1448b is relatively stiff. Further, in Figure 14, the redirector 946 (illustrated in Figure 9A) can be fixedly secured to the second guide side 1448bb.

[00288] It should be noted that other designs of the guide assembly are possible. For example, the guide assembly can be a butterfly type flexure.

[00289] It should also be noted that the materials utilized in the guide assemblies 1448b provided herein can varied to achieve the design characteristics of the system.

[00290] In one non-exclusive implementation, the guide assembly 1448b can be made of a material having the desired stiffness, and a relatively high thermal conductivity to reduce the amount of expansion and/or contraction of the guide assembly 1448b during operation of the laser assembly. A non-exclusive example of a suitable material includes titanium, or stainless steel.

[00291] In certain implementations, the flexures can be preloaded.

[00292] It should be noted that many different, non-exclusive, implementations of the laser assembly are described herein above, and below. In these configurations, the output beam can be fiber coupled, or launched into free-space. Furthermore, the laser assemblies can be designed to generate any wavelength range of light as necessary for the application of the laser assembly. Importantly, not all possible variations of the present design are illustrated in the Figures provided herewith.

[00293] The implementations of the laser assemblies provided herein, are rugged (storage temperature, operating temperature, vibration, shock insensitive), compact, high powered, low SWaP, reliable, tunable, narrow linewidth ECDL which works in a variety of applications. For example, the implementations can be designed for any wavelength from 360 to 2000nm. The implementations can be hermetically sealed, and not susceptible to RF radiative, conductive emissions, acoustic emissions and ultrasonic emissions.

[00294] Figure 15A is a partly exploded, perspective view of another implementation of the laser assembly 1510. In Figure 15A, the laser assembly 1510 is fiber coupled, and a portion of the laser frame 1514, and a portion of the optical fiber assembly 1534 are visible. In this Figure, the optical fiber assembly 1534 includes an optical fiber 1534b that extends through the laser frame 1514, and a fiber cover 1534c (illustrated away from the laser frame 1514) that covers the junction where the optical fiber 1534b extends through the laser frame 1514. In one implementation, the optical fiber assembly 1534 includes a metal jacket to attenuate radiofrequency waves and inhibit radiofrequency waves from entering the laser frame 1514.

[00295] It should be noted that the laser assembly 1510 can be designed to include a system controller 36 (illustrated in Figure 1) and/or a power supply 38 (illustrated in Figure 1 ) similar to the designs described above and illustrated in Figure 1.

[00296] In the non-exclusive implementation of Figure 15A, the laserframe 1514 includes an outer frame 1562 that houses, encircles and encloses many of the other components of the laser assembly 1510. In one, non-exclusive design, the outer frame 1562 includes a rigid, outer frame base 1562a, a rigid, outer frame top 1562b, one or more outer frame fasteners 1562c, and an electrical feedthrough connector 1562d. In this design, for example, (i) the outer frame base 1562a is generally box shaped, (ii) the outer frame top 1562b is generally flat plate shaped, (iii) the outer frame fasteners 1562c (e.g. , bolts) selectively secure the outer frame top 1562b to the outer frame base 1562a, and (iv) the electrical feedthrough connector 1562d connects the system controller 36 to the components within the outer frame 1562. However, other configurations of the outer frame 1562 are possible. As an example, the outer frame top 1562b and/or the outer frame base 1562a can have a thickness of at least two or three millimeters.

[00297] Figure 15B is a cut-away view of the laser assembly 1510 of Figure 15A taken on line 15B-15B in Figure 15A without the fiber cover 1534c (illustrated in Figure 15A) of the optical fiber assembly 1534. Figure 15B illustrates that the laser frame 1514 includes (i) the outerframe 1562, (ii) an innerframe 1564, and (iii) a temperature controller 1514c. In this non-exclusive design, (i) the outer frame 1562 forms an outer chamber 1562e that houses, encircles, encloses the inner frame 1564, the temperature controller 1514c, and the light generating components of the laser assembly 1510; (ii) the temperature controller 1514c includes a thermoelectric cooler 1514ca that is positioned between the outer frame 1562 and the inner frame 1564; and (iii) the inner frame 1564 1562 forms an inner chamber 1564a that houses, encircles and encloses the light generating components. It should be noted that the outer frame 1562, and/or the inner frame 1564 can alternatively be referred to as a first frame or a second frame.

[00298] In one non-exclusive implementation, the outer frame 1562 optionally includes an outer gasket 1562f (e.g., an EMI gasket) between the outer frame top 1562b to the outer frame base 1562a to inhibit electromagnetic fields/influences from entering at this intersection. Further, the outer frame 1562 can include a flex connector 1562g that electrically connects the feedthrough connector 1562d to the inner frame 1564.

[00299] In this design, the outer frame 1562 provides a Faraday cage around the inner frame 1564 and the light generating components of the laser assembly 1510. Stated differently, the outer frame 1562 isolates the inner frame 1564 and the light generating components from electromagnetic fields/influences, radiofrequency radiation, and acoustic noise that occur outside of the laser frame 1514. As a result thereof, the wavelength of the output beam generated by the laser assembly 1510 will be more stable and accurate.

[00300] Further, the outer frame 1562 provides thermal protection for the inner frame 1564, and can inhibit air from circulating (no air motion) around the outside of the inner frame 1564. As a result thereof, the temperature of the inner frame 1564 and the components within the inner frame 1564 can be maintained with greater accuracy. Temperature changes adversely influence the optical pathlength and wavelength of the output beam. As a result of the outer frame 1562, the wavelength of the output beam generated by the laser assembly 1510 will be more stable and accurate.

[00301] For example, the outer frame 1562 and/or the inner frame 1564 can be made of a material having the desired stiffness and thickness, and a relatively high thermal conductivity (e.g., at least 100, or 150 watts per meter Kelvin (W/mK)). Nonexclusive examples of suitable material includes molybdenum copper “MoCu” or titanium, aluminum or copper. [00302] With the present design, the two frames 1562, 1564 form a double walled enclosure for the active components of the laser assembly 1510 to provide a conductive shield that inhibit electromagnetic fields/influences, radiofrequency radiation, and acoustic noise from adversely influencing the laser assembly 1510. The two frames 1562, 1564 also provide an isothermal enclosure with near zero thermal gradients with thermally conductive lids, and interfaces.

[00303] In one, non-exclusive design, the inner frame 1564 includes a rigid, inner frame base 1564b and a rigid, inner frame top 1564c. In this design, for example, (i) the inner frame base 1564a is generally box shaped, and (ii) the inner frame top 1564c is generally flat plate shaped. In this configuration, the inner frame top 1564c can be secured to and sealed to the inner frame base 1564b with a weld or with another type of fastener. It should be noted that other configurations of the inner frame 1564 are possible.

[00304] With the present design, the inner frame 1564 also protects the light generating components from electromagnetic fields/influences, radiofrequency radiation, and acoustic noise that occur outside of the laser frame 1514. Further, the inner frame 1564 provides thermal protection for the components inside the inner frame 1564. As a result thereof, the wavelength of the output beam will be more stable and accurate.

[00305] In certain designs, the innerframe 1564 is a hermetically sealed package with low outgassing. With this design, the inner frame 1564 can provide a controlled environment for the other light generating components of the laser assembly 1510. As alternative, non-exclusive examples, the controlled environment can be a vacuum, an inert gas, or another fluid. For example, the controlled environment can be selected to match and provide the best environment for the emitter 1516 (illustrated in Figure 15D). In one implementation, the controlled environment can be a fluid that improves the reliability of the emitter 1516. Still alternatively, for example, desiccant or another drying agent can be positioned in the inner frame 1564 to trap moisture and/or gases that could absorb laser emissions, cause corrosion, and/or cause condensation. In a different design, the inner frame 1564 can be unsealed.

[00306] Additionally, the temperature controller 1514c includes a temperature sensor (not shown in Figure 15B) (e.g., a thermistor) that provides feedback for closed loop control of the thermoelectric cooler 1514ca. With this design, the entire inner frame 1564 is maintained at the desired temperature. As a non-exclusive example, the thermoelectric cooler 1514ca can be used to control the temperature of the inner frame 1564 to within a milli-Kelvin or better of a desired temperature, in a closed loop fashion.

[00307] In one implementation, a single temperature sensor is used, and the thermoelectric cooler 1514ca maintains the inner frame 1564 or a portion thereof at the desired temperature.

[00308] In one design, the temperature sensor is positioned near the emitter 1516 and the thermoelectric cooler 1514ca can actively control the temperature of the emitter 1516 and/or another portion of the inner frame 1564. In certain implementations, it is important that a mounting base 1564ba is thermally stable to inhibit unwanted changes to the optical path length of the external cavity, and to inhibit unwanted shifts in the positions of the components.

[00309] Figure 15B also illustrates that the optical fiber assembly 1534 can extend through the two frames 1562, 1564, and the fiber inlet facet 1534a is positioned within the inner frame 1564. In one implementation, the optical fiber assembly 1534 is double ferruled for hermetic sealing of the inner frame 1564.

[00310] Figure 15C is a perspective view of the laser assembly 1510 of Figure 15A without the fiber cover 1534c (illustrated in Figure 15A), and with the outer frame top 1562b (illustrated in Figure 15A) removed to expose the inner frame 1564.

[00311] Figure 15C also illustrates that that the outer frame base 1562a includes an outer frame aperture 1562aa, and the optical fiber 1534b extends through the outer frame aperture 1562aa. In this design, the fiber cover 1534c (illustrated in Figure 15A) fits over the optical fiber 1534b and covers the outer frame aperture 1562aa. With this design, the fiber cover 1534c can inhibit electromagnetic fields/influences, radiofrequency radiation, and acoustic noise that occur outside of the laser frame 1514 from entering via the outer frame aperture 1562aa. Further, the fiber cover 1534c inhibits moving air from entering via the outer frame aperture 1562aa.

[00312] In certain non-exclusive implementations, the optical fiber 1534b can include a corrugated metal, fiber jacket (cladding). With this design, the optical fiber 1534b is electrically connected to the outer frame 1562 to additionally attenuate the electromagnetic forces, and inhibit these forces from entering the inner frame 1564.

[00313] Moreover, Figure 15C also illustrates that the outer frame 1562 can optionally include an aperture cover 1562h that is rotatably coupled to the outer frame base 1562a. With this design, for free-space implementations without the optical fiber 1534b, the aperture cover 1562h can be selectively rotated to selectively cover (shutter) the outer frame aperture 1562aa to selectively inhibit light from exiting the outer frame aperture 1562aa.

[00314] Figures 15D and 15E are alternative perspective views, and Figure 15F is a top view of the laser assembly 1510 of Figure 15A, without the fiber cover 1534c (illustrated in Figure 15A), and with the outer frame top 1562b (illustrated in Figure 15A) removed to expose the inner frame 1564, and the inner frame top 1564c (illustrated in Figure 15B) removed to expose the light generating components of the laser assembly 1510.

[00315] It should be noted that in the configuration illustrated in Figures 15D- 15F, the light generated by the laser assembly 1510 is coupled into the optical fiber 1534b that extends away from the laser frame 1514. Thus, a separate connector (not shown) is not required that can degrade the output power.

[00316] In the implementation of Figures 15D-15F, the inner frame base 1564b can include a mounting base 1564ba, and four side walls 1564bb. In this design, (i) the mounting base 1564ba is rigid and generally flat, and (ii) the emitter 1516, the emitter lens 1518, the transmission grating assembly 1520, the redirector assembly 1522, the beam shaper 1524, the beam director assembly 1566, the optical isolator 1526, the polarization adjuster assembly 1530, the pointer adjuster assembly 1528, and the coupling lens assembly 1532 are secured directly or indirectly to the mounting base 1564ba.

[00317] Additionally, in certain implementations, the four side walls 1564bb can include a first wall opening 1564bbA that allows the optical fiber 1534b to extend into the inner frame 1564. Further, the four side walls 1564bb can include a second wall opening 1564bbB that allows for access into the inner frame 1564 for curing glue that secures one or more components to the mounting base 1564ba. In this design, the first wall opening 1564bbA can be sealed when the optical fiber 1534b is installed, and the second wall opening 1564bbB can be sealed with a plug.

[00318] In one implementation, the optical fiber assembly 1534 includes a fiber mount 1534d that secures the optical fiber assembly 1534 to the inner housing 1564 and a portion of the optical fiber assembly 1534 extends through the first wall opening 1564bbA. In this design, when the fiber inlet facet 1534a is properly positioned, the fiber mount 1534d can be fixedly attached (e.g., via UV cured glue) to the side walls 1564bb. [00319] In certain non-exclusive designs, the fiber inlet facet 1534a can be angled to inhibit light from being reflected back into the cavity.

[00320] With reference to Figure 15F, the laser assembly 1510 can also include a fastener assembly 1568 (e.g., one or more fasteners) that selectively secures the inner frame 1564 to the outer frame 1562 with the thermoelectric cooler 1514ca (illustrated in Figure 15B) therebetween.

[00321] Figure 15F also illustrates the flex connector 1562g that electrically connects the feedthrough connector 1562d to the inner frame 1564. Moreover, Figure 15F illustrates that the inner frame 1564 includes an inner flex connector 1564d that is positioned within the innerframe 1564. In this design, the inner flex connector 1564d is electrically connected to flex connector 1562g, and inner flex connector 1564d is electrically connected to components within the inner frame 1564.

[00322] In the non-exclusive implementation illustrated in Figures 15D-15F, the laser assembly 1510 includes an emitter 1516, an emitter lens 1518, a transmission grating assembly 1520, a redirector assembly 1522, a beam shaper 1524, a beam director assembly 1566, an optical isolator 1526, a polarization adjuster assembly 1530, a pointer adjuster assembly 1528, and a coupling lens assembly 1532 that are positioned within the inner frame 1564. Alternatively, for example, the laser assembly 1510 can be designed to include more components or fewer components than are illustrated in these Figures. For example, the beam director assembly 1566 can be eliminated, and the components can have a generally linear arrangement instead of the folded configuration shown in these Figures.

[00323] The design of the emitter 1516, the emitter lens 1518, the transmission grating assembly 1520, the redirector assembly 1522, the beam shaper 1524, the beam director assembly 1566, the optical isolator 1526, the polarization adjuster assembly 1530, the pointer adjuster assembly 1528, and/or the coupling lens assembly 1532 can be varied to achieve the desired tunable range and the desired performance of the laser assembly 1510. As an overview, the present invention is uniquely designed so that one or more components can be added or swapped to change the wavelength tuning range and/or performance of the laser assembly 1510. More specifically, the laser assembly 1510 can include an emitter mount (e.g., a heatsink) 1517 that couples the emitter 1516 to the laser frame 1514, and the emitter mount 1517 can has a unique geometry that is designed to allow for selectively receiving one or more different emitters 1516 on the heatsink 1517. For example, the emitter 1516 that is coupled to the emitter mount 1517 in Figure 15F can be designed to generate light in a first wavelength range. Alternatively, a second, different, replacement emitter 1516r (illustrated as a box) that generates light in a second wavelength range that is different than the first wavelength range can be selectively attached to emitter mount 1517.

[00324] The emitter 1516 generates the emitter beam 16a (illustrated in Figure 1 ). The emitter 1516 can be similar to the corresponding emitter 16 described above and illustrated in Figure 1. Further, the design of the emitter 1516 can be varied to achieve the desired characteristics of the output beam 12. Non-exclusive examples of suitable wavelengths for the emitter 16 and the replacement emitter 1516r can include within the ultraviolet range, the visible range, the near infrared range, the infrared range, the mid-infrared range, and the far infrared range.

[00325] In one implementation, the emitter 1516 includes an emitter flex circuit 1516a that electrically connects the emitter 1516 to the inner flex connector 1564d. With this design, the emitter flex circuit 1516a is designed to suit the requirements of the emitter 1516. Stated differently, the inner flex connector 1564d can remain the same, but the emitter 1516 and the emitter flex circuit 1516a can be exchanged for a different, replacement emitter flex circuit 1516ar (illustrated as a box) that connects (and corresponds to) the replacement emitter 1516r to the inner flex connector 1564d. Thus, the emitter flex circuit 1516a, 1516a allows for different emitters 1516, 1516r to be easily electrically connected to the inner flex connector 1564d.

[00326] Importantly, the unique architecture of the present design enables different emitters 1516, 1516r (e.g., 5.6mm TO-CAN, 9.0mm TO-CAN, C-mount, D- mount) to fit within the inner housing 1564. As a result thereof, the laser assembly 1510 can be designed to generate light anywhere in the entire spectrum. For example, the laser assembly 1510 can be designed to generate light anywhere in the spectral range of three hundred and sixty nanometers to two microns.

[00327] Stated differently, many different emitters 1516, 1516r can positioned in the same laser frame 1514. This allows for different laser assemblies 1510 to be made using common components.

[00328] The emitter lens 1518 collimates the emitter beam 16a (illustrated in Figure 1) emitted from the emitter 1516. The emitter lens 1518 can be similar to the corresponding emitter lens 18 described above and illustrated in Figure 1 . The design of the emitter lens 1518 is changed to correspond to the design of the emitter 1516. [00329] The transmission grating assembly 1520 includes a transmission grating 1520a that is positioned in the path of the emitter beam 16a, and the transmission grating 1520a is a part of the primary external cavity of the laser assembly 1510. The transmission grating assembly 1520 can be similar to the corresponding transmission grating assembly 1520 described above and illustrated in Figure 1 . The design of the transmission grating assembly 1520 is changed to correspond to the design of the emitter 1516 and to achieve the desired performance of the laser assembly 1510.

[00330] In non-exclusive implementation of Figure 15F, the light transmitted through the transmission grating assembly 1520 is sequentially directed through (i) the beam shaper 1524, (ii) the beam director assembly 1566, (iii) the isolator 1526, (iv) the polarization adjuster assembly 1530, (v) the pointer adjuster assembly 1528, and (vi) the coupling lens assembly 1532 to become the output beam that is coupled to the optical fiber assembly 1534.

[00331] The design of the transmission grating assembly 1520 is changed to correspond to the design of the emitter 1516.

[00332] Similar to the corresponding redirector assembly 22 described above and illustrated in Figure 1 , the redirector assembly 1522 can include (i) a redirector 1546 that redirects the second beam 42 (illustrated in Figure 1 ), and forms the second cavity end; and (ii) a redirector mover 1548 that precisely and selectively moves the redirector 1546 (and the second cavity end) to adjust the optical path length of the primary external cavity, and the primary lasing center wavelength of the primary external cavity.

[00333] With this design, the redirector assembly 1522 receives the second beam 42 (illustrated in Figure 1) and redirects the second beam 42 as a redirected beam 44 (illustrated in Figure 1 ) back at the transmission grating 1520a. The redirected beam 44 that impinges upon the transmission grating 1520a is transmitted through, and diffracted into at least (i) a redirected first beam 44a (illustrated in Figure 1 ) that is directed along a redirected first beam axis 44aa (illustrated in Figure 1 ); and (ii) a redirected second beam 44b (illustrated in Figure 1 ) that retraces the path back to the emitter lens 1518 and the emitter 1516.

[00334] The type of redirector assembly 1522 utilized can be varied to correspond to the design of the emitter 1516, and to achieve the desired performance of the laser assembly 10. As provided above, in the external cavity arrangement of Figure 15, the position of the redirector 1546 will primarily dictate (i) the optical path length of the primary external cavity, (ii) the center wavelength of the primary external cavity, and (iii) the primary, center wavelength of the emitter beam 16a from the emitter 1516, and the output beam.

[00335] As provided herein, in one, non-exclusive implementation, the redirector mover 1548 precisely moves the redirector 1546 in a closed loop fashion about a selected pivot axis (not shown in Figure 15). As provided herein, the selected pivot axis is chosen because movement of the redirector 1546 about that axis inhibits mode hops during the tuning of the center wavelength. Importantly, the location of the selected pivot axis of the redirector 1546 will vary according to the design and location of the other components of the laser assembly 1510.

[00336] With this design, the redirector 1546 is precisely moved to tune the center wavelength, without moving the transmission grating 1520a, and without influencing the path of the first beam 40.

[00337] In one implementation, during assembly, the redirector assembly 1522 can be freely moved (e.g., translated and rotated) to different locations on the mounting base 1564ba until the redirector 1546 is properly positioned for mode-hop free tuning. Next, the redirector assembly 1522 can be fixedly secured to the mounting base 1564ba with an adhesive, or another fastener. It should be noted that different emitters 1516 will have different selected pivot axis. Thus, the position of the redirector assembly 1522 will be different for different emitters 1516.

[00338] In Figures 15D-15F, the redirector 1546 is precisely moved to make relatively slow and rough (large) tuning of optical path length of the primary external cavity, and the center wavelength of the emitter beam. In contrast, the system controller 36 (illustrated in Figure 15) can selectively adjust the current directed to the emitter 1516 to selectively control (change) the index of refraction of the emitter 1516 to selectively make relatively rapid, and fine (small) changes to the lasing center wavelength of the emitter beam.

[00339] The beam shaper 1524 shapes the beam that has been transmitted through the transmission grating 1520a. The beam shaper 1524 can be similar to the corresponding beam shaper 24 described above and illustrated in Figure 1 . In certain designs, the beam is not perfectly circular, and the optical fiber assembly 1534 is circular. In one example, the beam shaper 1524 reshapes the beam to have circular cross-sectional shape to match the optical fiber assembly 1534. As non-exclusive examples, the beam shaper 1524 can include one or more optical elements, including one or more: (i) axicon lenses; (ii) powell lenses; (iii) prisms; (iv) metasurfaces; (v) diffractive optical elements; (vi) engineered diffusers; (vii) aspheric corrector plates; and/or (viii) anamorphic prisms.

[00340] The beam director assembly 1566 redirects the light exiting the beam shaper 1524 and allows for the components of the laser assembly 1510 to have a compact, folded configuration.

[00341] In one, non-exclusive implementation, the beam director assembly 1566 is a dove prism. The pointing of the dove prism is insensitive to slight mechanical movements, and does not change the pointing. Alternatively, the beam director assembly 1566 can include one or more mirrors (not shown). However, any movement of the mirrors can adversely influence the pointing of the beam. Still alternatively, the components of the laser assembly 1510 can be arranged in a linear orientation, without the beam director assembly 1566.

[00342] The optical isolator 1526 inhibits light from the subsequent components along the optical path of the beam from being reflected back to the transmission grating 1520a and the external cavity. The optical isolator 1526 can be similar to the corresponding optical isolator 26 described above and illustrated in Figure 1. The design of the optical isolator 1526 is changed to correspond to the design of the emitter 1516, the design of the external cavity, and the wavelengths of light generated by the emitter 1516. In Figure 15F, the light that exits the isolator 1526 is directed at the polarization adjuster assembly 1530.

[00343] In certain designs, the inlet facet to the optical isolator 1526 can be slightly angled to inhibit light from being reflected back to the transmission grating 1520a and into the optical cavity.

[00344] In one implementation, the optical isolator 1526 includes an isolator body 1526a, an isolator base 1526b, and one or isolator fasteners 1526c that selectively secure the isolator base 1526b to the mounting base 1564ba. With this design, during assembly of the laser assembly 1510, with the isolator base 1526b secured to the mounting base 1564ba, the isolator body 1526a can moved until it is properly aligned. Next, the isolator body 1526a can be secured to the isolator base 1526b with an adhesive or another type of fastener.

[00345] The polarization adjuster assembly 1530 can be somewhat similar to the corresponding polarization adjuster assembly 30 described above and illustrated in Figure 1. The design of the polarization adjuster assembly 1530 is changed to correspond to the design of the emitter 1516.

[00346] In certain implementations, the ggoptical fiber assembly 1534 is a polarization maintaining optical fiber (e.g., includes stress rods that maintain the polarization). In a specific example, the device that utilizes the output beam from the optical fiber assembly 1534 is designed to function best with an output beam having a desired polarization (e.g., a linear polarization). In this example, the emitter 1516 can be designed so that the first beam leaving the transmission grating 1520a has the desired polarization (e.g., linear polarization), and the optical fiber assembly 1534 can be designed to maintain light having the desired polarization (e.g., the linear polarization). However, alignment and other issues can cause the first beam to not exactly have the desired polarization. With the present design, the polarization adjuster assembly 1530 can be adjusted to change (if necessary) the polarization of the first beam so that the output beam has the desired polarization (e.g., linear polarization) before it enters the optical fiber assembly 1534.

[00347] A non-exclusive example of a suitable polarization adjuster assembly 1530 is described below in more detail in reference to Figures 15P-15S.

[00348] The pointer adjuster assembly 1528 is adjusted to precisely adjust the pointing of the output beam. As a result thereof, the output beam is accurately pointed, and can be accurately centered and focused on the fiber inlet facet 1534a to maximize fiber coupling of the output beam.

[00349] As provided herein, during operation of the laser assembly 1510, temperature cycles, stress relief, and/or vibration can cause one or more of the components to move slightly, and adversely influence the pointing of the output beam. In certain designs, the laser assembly 1510 can be temperature cycled and/or vibrated to get the components to settle in position for final alignment. Subsequently, the pointer adjuster assembly 1528 can be used to adjust and correct the pointing of the output beam.

[00350] The pointer adjuster assembly 1528 can be somewhat similar to the corresponding pointer adjuster assembly 28 described above and illustrated in Figure 1. Alternatively, a non-exclusive example of another type of pointer adjuster assembly 1528 is described below in more detail in reference to Figures 15L-15O.

[00351] The coupling lens assembly 1532 directs and couples the output beam to the fiber inlet facet 1534a of the optical fiber assemblyl 534. More specifically, the coupling lens assembly 1532 precisely focuses the output beam onto the fiber inlet facet 1534a of the optical fiber 1534. The coupling lens assembly 1532 can be somewhat similar to the corresponding coupling lens assembly 32 described above and illustrated in Figure 1.

[00352] Figure 15G is a perspective view of a portion of the laser assembly 1510 of Figure 15A. More specifically, Figure 15G illustrates the emitter 1516, the emitter lens 1518, the transmission grating assembly 1520, the redirector assembly 1522, the beam shaper 1524, the beam director assembly 1566, the optical isolator 1526, the polarization adjuster assembly 1530, the pointer adjuster assembly 1528, the coupling lens assembly 1532, the optical fiber assembly 1534, and the inner flex connector 1564d.

[00353] It should be noted that Figure 15G also illustrates that the laser assembly 1510 additionally can include one or more light traps (light absorbers) that capture stray and/or unwanted reflected light, and inhibit this light from entering into and disrupting the laser cavity. For example, the laser assembly 1510 can include a first light trap 1570a that captures the redirected first beam 44a (illustrated in Figure 1 ), and a second light trap 1570b that captures stray light reflected off of the fiber inlet facet 1534a or another surface.

[00354] Moreover, Figure 15G also illustrates the fiber mount 1534d for the optical fiber assembly 1532. In this design, the fiber mount 1534d includes a first mount 1534da that secures the optical fiber assembly 1534 to the inner frame 1564 (illustrated in Figure 15F) and a second mount 1534db that secures the fiber tip to the mounting base 1564ba (illustrated in Figure 15F). In this design, (i) the optical fiber assembly 1534 extends through the wall opening 1564bba (illustrated in Figure 15E), (ii) the first mount 1534da is generally disk shaped and is secured to the inner frame 1564; and (iii) the second mount 1534db is an “L” shaped bracket that secures the fiber tip to the mounting base 1564ba. However, other mounting arrangements are possible.

[00355] Figure 15G also illustrates how to package connector wires 1548ab for a redirector actuator assembly 1548a of the redirector assembly 1522 to inhibit vibration. Stated differently, the connector wires 1548ab can be tacked to inhibit the coupling of vibration into the guide assembly 1548b (e.g., flexure) of the redirector assembly 1522. In certain designs, the connector wires 1548ab have a low natural frequency. Moreover, the connector wires 1548ab can be stiffened by tacking them in many places to the rigid package to increase the natural frequency, and reduce the displacement of the connector wires 1548ab. This inhibits vibration from being coupled into the inner flex connector 1624d and the other components of the laser cavity.

[00356] Figure 15H is a perspective view of another portion of the laser assembly 1510 of Figure 15A. More specifically, Figure 15H illustrates the emitter 1516, the emitter lens 1518, the transmission grating assembly 1520, the redirector assembly 1522, the beam shaper 1524, the beam director assembly 1566, the optical isolator 1526, the polarization adjuster assembly 1530, the pointer adjuster assembly 1528, the coupling lens assembly 1532, and the optical fiber assembly 1534 from Figure 15G without the inner flex connector 1564d.

[00357] Figure 151 is a perspective view of another portion of the laser assembly 1510 of Figure 15A. More specifically, Figure 151 illustrates the emitter 1516, the emitter lens 1518, and the redirector assembly 1522.

[00358] Figure 15J is a top view and Figure 15K is a perspective view of the redirector assembly 1522. In this, non-exclusive one implementation, the redirector assembly 1522 includes (i) a redirector 1546 that redirects the second beam 42 (illustrated in Figure 1 ) and forms the second cavity end; and (ii) a redirector mover 1548 that retains, and precisely and selectively moves the redirector 1546 (and the second cavity end) to adjust the optical path length of the primary external cavity, and the primary lasing center wavelength of the primary external cavity.

[00359] A non-exclusive example of a suitable redirector 1546 can include a retroreflector such as a porro prism. The retroreflector can be coated with a material having a very high reflectivity for the spectral range or total internal reflection of the light generated by the emitter 1516 (illustrated in Figure 15A).

[00360] The redirector mover 1548 is controlled by the system controller 36 (illustrated in Figure 1 ) to precisely move the redirector 1546 to precisely adjust the optical path length of the primary external cavity. This allows for the precise tuning of the center wavelength of the output beam 12. In one, non-exclusive implementation, the redirector mover 1548 precisely moves the redirector 1546 in a closed loop fashion about a selected pivot axis (not shown in Figure 1). In certain implementations, the selected pivot axis is chosen because movement of the redirector 1546 about that axis inhibits mode hops during the tuning of the center wavelength. Stated alternatively, in certain designs, the redirector mover 1548 moves the redirector 1546 in a fashion that inhibits mode hops while tuning over a desired spectral range. In one, non-exclusive implementation, the redirector mover 1548 selectively pivots the redirector 1546 about the selected pivot axis to allow for mode hop free tuning. The location of the selected pivot axis will depend upon the design and location of the components of the laser assembly 1510.

[00361] In one implementation, (e.g., illustrated in Figure 15J) the redirector mover 1548 can include a redirector actuator assembly 1548a, a guide assembly 1548b for guiding movement (e.g., pivoting) of the redirector 1546, a sensor assembly 48c (illustrated in Figure 1 ) for sensing the position of the redirector 1546 for closed loop control of the position of the redirector 1546, and a redirector base 1548d that secures the guide assembly 1548b to the mounting base 1564ba (illustrated in Figure 15F).

[00362] As non-exclusive examples, the actuator assembly 1548a can include one or more (i) piezoelectric actuator(s), such as shear piezos (e.g., bidirectional, passive or active running), piezo stacks, and/or piezo clips; (ii) bimetallic strip(s); (iii) thermoelectric cooler(s); (iv) heater(s), (v) voice coil(s), (vi) stepper motor(s), (vii) solenoid(s), (viii) electrostriction, (ix) motor(s), and/or (x) actuator(s).

[00363] As non-exclusive examples, the guide assembly 1548b can include one or more (i) flexure(s); (ii) bearing(s); and/or (iii) other rotary guide(s). In a specific example, the guide assembly 48b can be a flexure made of nitinol.

[00364] The redirector base 1548d can include a generally flat surface that can be secured to the mounting base 1564ba. With this design, the redirector base 1548d can be moved relative to the mounting base 1564ba until the desired, selected pivot axis is located. Subsequently, the redirector base 1548d can be fixed secured to the mounting base 1564ba with an adhesive or another type of fastener.

[00365] Figure 15L is a perspective view of the pointer adjuster assembly 1528 from Figure 15A. Figure 15L also illustrates an input beam 1572a (illustrated with a dashed line), an output beam 1572b (illustrated with a dashed line), and an orientation system (TUV) that is referenced to the incoming beam 1572a. The T, II, V axes can alternatively be referred to as the first, second, or third axis.

[00366] As provided above, during operation of the laser assembly 1510 (illustrated in Figure 15A), temperature cycles, stress relief, and/or vibration can cause one or more of the components to move slightly, and adversely influence the pointing of the output beam. In certain designs, the laser assembly 1510 can be temperature cycled and/or vibrated to get the components to settle in position for final alignment. Subsequently, the pointer adjuster assembly 1528 can be used to adjust and correct the pointing of the output beam 1572b.

[00367] In the non-exclusive implementation of Figure 15L, the pointer adjuster assembly 1528 is uniquely designed to adjust the pointing and/or translation of the output beam 1572b with at least four degrees of freedom. More specifically, in Figure 15L, the pointer adjuster assembly 1528 can be adjusted to change the pointing of the output beam 1572b with two degrees of freedom (e.g., in yaw (rotation about the T axis) and in pitch (rotation about the V axis)), and change the translation of the output beam 1572b with two degrees of freedom (e.g., the T axis and V axis).

[00368] In Figure 15L, the pointer adjuster assembly 1528 includes an adjuster base 1528a, a first pointer adjuster 1528b, a second pointer adjuster 1528c, an adjuster fastener 1528d (illustrated with a couple of small dots), and one or more base fasteners 1528e. In this design, the base fasteners 1528e secure the adjuster base 1528a to the mounting base 1564ba (illustrated in Figure 15F). Further, the adjuster fastener 1528d can be an adhesive.

[00369] In one non-exclusive implementation, (i) each pointer adjuster 1528b, 1528c is a wedged window and has a cylindrical shape, and (ii) the first pointer adjuster 1528b and the second pointer adjuster 1528c are arranged in series, and are spaced apart so that the light travels through the first pointer adjuster 1528b to the second pointer adjuster 1528c. Alternatively, one or both pointer adjusters 1528b, 1528c can have a spherical shaped segment.

[00370] In certain designs, one or both pointer adjusters 1528b, 1528c can be individually and selectively moved relative to the adjuster base 1528a to adjust the pointing and translation of the outgoing beam 1572b. For example, (i) one or both pointer adjusters 1528b, 1528c can be individually rotated about the II axis to selectively adjust pointing of the outgoing beam 1572b, and/or (ii) one or both pointer adjusters 1528b, 1528c can be individually tipped (rotated about the V axis) or tilted (rotated about the T axis) rotated about the II axis to adjust the translation of the outgoing beam 1572b. In this design, (i) rotation results in pointing adjustment, and (ii) tipping and tilting results in beam translation adjustment. Stated differently, (i) the pointer adjusters 1528b, 1528c can be selectively and independently rotated relative to the adjuster base 1528a to selectively adjust the pointing of the inlet beam 1572a wherein two degrees of freedom; and (ii) the pointer adjusters 1528b, 1528c can be selectively and independently tipped and tilted relative to the adjuster base 1528a to selectively adjust the translation of the inlet beam 1572a with two degrees of freedom.

[00371] In one implementation, each point adjuster 1528b, 1528c is a prism, that can be individually and independently rotated and tilted. Light traveling through a single prism will emerge from the prism at some angle relative to the incoming light. In certain designs, by using two prisms with the same wedge angle, the output angle of the incoming beam can be adjusted anywhere from zero degrees to twice the output angle of a single prism. With the present design, the position and angle of the output beam 1572b can now be controlled anywhere within the region of interest by adjusting the roll and tilt of the two point adjuster 1528b, 1528c.

[00372] In Figure 15L, the adjuster base 1528a is uniquely designed to allow for the desired movement of the pointer adjusters 1528b, 1528c. In one implementation, the adjuster base 1528a includes (i) a rigid base body 1528aa, (ii) a first receiver 1528ab that receives a portion of the first pointer adjuster 1528b, and (iii) a second receiver 1528ac that receives a portion of the second pointer adjuster 1528c. In this design, the receivers 1528ab, 1528ac are slightly offset.

[00373] Further, in one implementation, the base body 1528aa is generally rectangular shaped, and each receiver 1528ab, 1528ac is a depression that has the shape of a section of a sphere (e.g., a spherical socket). With this design, (i) one or both pointer adjusters 1528b, 1528c can be individually rotated about the II axis within the receivers 1528ab, 1528ac, and/or (ii) one or both pointer adjusters 1528b, 1528c can be individually tipped (rotated about the V axis) or tilted (rotated about the T axis) rotated about the U axis within the receivers 1528ab, 1528ac. In one implementation, the pointer adjusters 1528b, 1528c can be moved to translate the output beam 1572b up to one millimeter to recent the output beam 1572b. In certain implementations, the pointer adjuster assembly 1528 can be used to displace the beam by yawing and pitching each of the pointer adjusters 1528b, 1528c

[00374] In the present design, there are no blind-spot like in conventional Risley pair. Further, the pointer adjuster assembly 1528 offers high stability, transmissive fine tuning compared to mirrors.

[00375] In one implementation, the adjuster fastener 1528d can be a puddle of glue in each receiver 1528ab, 1528ac. The glue can be cured after the pointer adjusters 1528b, 1528c are properly positioned. However, other types of fasteners can utilized. [00376] During manufacturing, the laser assembly 1510 (illustrated in Figure 15A) can be temperature cycled and vibrated to get the position of the components to settle. After the laser assembly 1510 is ready forfinal alignment, the pointer adjusters 1528b, 1528c can be individually moved and adjusted until a measured output power in the optical fiber assembly 1534 (illustrated in Figure 15A) is maximized. Generally, maximum output power is achieved when the output beam 1572b is properly focused on the fiber inlet facet 1534a. When the maximum is achieved, the pointer adjusters 1528b, 1528c can be fixedly secured to the adjuster base 1528a.

[00377] It should be noted that the laser assembly 1510 can be designed to include more than one pointer adjuster assembly 1528. Further, the base fastener 1528e allows for the pointer adjuster assembly 1528 to be replaced and/or reworked if necessary.

[00378] Figure 15M is a perspective view of the adjuster base 1528a including (i) the rigid base body 1528aa, (ii) the spherical shaped, first receiver 1528ab, and (iii) the spherical shaped, second receiver 1528ac.

[00379] Figure 15N is a simplified illustration of the pointer adjuster assembly 1528 with the two pointer adjusters 1528b, 1528c at two different beam translating positions and no change in pointing direction, with the input beam 1572a, and the output beam 1572b.

[00380] Similarly, Figure 150 is a simplified illustration of the pointer adjuster assembly 1528 with the two pointer adjusters 1528b, 1528c at two different pointing positions, with the input beam 1572a, and the output beam 1572b.

[00381] Figure 15P is a perspective view of a portion of the optical isolator 1526, a portion of the mounting base 1564ba, and one implementation of the polarization adjuster assembly 1530.

[00382] In this design, the polarization adjuster assembly 1530 is positioned to precisely adjust the polarization of the beam 1573 (illustrated with a dashed arrow). As a result thereof, the beam 1573 will have a polarization that best matches the optical fiber assembly 1534 (illustrated in Figure 15A) and/or the device (or specific application) that utilizes the beam 1573.

[00383] In one non-exclusive implementation, the polarization adjuster assembly 1530 includes (i) a polarization adjuster (e.g., a waveplate) 1530a, (ii) an adjuster mount 1530b (illustrated in phantom) that is secured to the mounting base 1564ba, and (iii) an adjuster fastener 1530c that fixedly secures the polarization adjuster 1530a to the adjuster mount 1530b. For example, the adjuster fastener 1530c can be an adhesive. In Figure 15P, the adjuster fastener 1530c is a spaced apart pair of adhesive spots. For example, the adhesive can be ultraviolet cured thixotropic adhesive.

[00384] In one design, the polarization adjuster 1530a can be selectively moved to adjust the polarization of the beam 1573 to allow for the fine adjustment of the polarization of the beam 1573 in space, and subsequently secured with the adjuster fastener 1530c to the adjuster mount 1530b. With this design, the beam 1573 can be a linear polarized beam, that is either parallel or perpendicular to the table.

[00385] As a non-exclusive example, the polarization adjuster 1530a can be a half waveplate, or a quarter waveplate. With this design, for example, after the laser assembly 1510 has been temperature cycled and/or vibrated, and is ready for final adjustment, the waveplate 1530a can be moved and adjusted until a measured polarization of the beam 1573 is the same as the desired polarization. When the desired polarization is achieved, the waveplate 1530a is fixedly secured to the mounting base 1564ba.

[00386] It should be noted that Figure 15P also includes an orientation system (A,B,C) that is referenced to the beam 1573. The A, B, C axes can alternatively be referred to as the first, second, or third axis. In this Figure the top of the mounting base 1564ba is in the A-C plane, and the adjuster fastener 1530c (adhesive spots) are spaced apart along the A axis.

[00387] Figure 15Q, Figure 15R, and Figure 15S are alternative views of a polarization adjuster 1530a of Figure 15P. These Figures also include the orientation system (A, B, C).

[00388] In one, non-exclusive implementation, the polarization adjuster 1530a has anisotropic properties. For example, the polarization adjuster 1530a can have a first coefficient of thermal expansion along a first axis (e.g., along the A axis), and a second coefficient of thermal expansion along a second axis (e.g., along the B axis). For example, the second coefficient of thermal expansion can be greater than the first coefficient of thermal expansion. As alternative, non-exclusive examples, the second coefficient of thermal expansion can be at least 10, 500, 100, 200 or 300 percent greater than the first coefficient of thermal expansion. With this design, the polarization adjuster 1530a will expand at different rates in different directions. [00389] In one design, the polarization adjuster 1530a is designed so that the first coefficient of thermal expansion along the first axis, approximately matches with the coefficient of thermal expansion for the mounting base 1564ba (illustrated in Figure 15P), and/or the adjuster mount 1530b (illustrated in Figure 15P). Further, as illustrated in Figure 15P, the polarization adjuster 1530a is mounted and retained at two spaced apart locations along the first axis. As used herein, in alternative examples, approximately matches means within 1 , 2, 10, 20, or 40 percent.

[00390] With this design, in the event the polarization adjuster 1530a heats up during usage, the polarization adjuster 1530a will expand at different rates in different directions. Because one axis of expansion matches the rest of the package (e.g., mounting base 1564ba and/or the adjuster mount 1530b), the polarization adjuster 1530a is less likely to deform (bend) during temperature changes. Also, the shear stress in the glue will be significantly less during temperature cycles.

[00391] In one non-exclusive example, the polarization adjuster 1530a can have a first coefficient of thermal expansion (CTE - 8 ppm/C) along the first axis (A axis), and a second coefficient of thermal expansion (CTE = 13.4 ppm/C) along the second axis (B axis). However, other rates/ ratios of thermal expansion can be utilized. Further, the two adjuster fasteners 1530c are highlighted and spaced apart along the first axis. With this design, the polarization adjuster 1530a expands at the same rate and concurrently with the adjuster mount 1530b (illustrated in Figure 15P) along the first axis, and the polarization adjuster 1530a is free to expand at a different rate along the second axis to inhibit bending.

[00392] Figure 15R illustrates that the polarization adjuster 1530a can include a first element 1530aa, and a second element 1530ab that are bonded together. For example, each element 1530aa, 1530ab can be a quartz disk.

[00393] In one design, the polarization adjuster 1530a can be mounted with a +/-5 degree mounting range.

[00394] Figure 16 is a simplified top view of another implementation of the redirector assembly 1622 including the redirector 1646, and the redirector mover 1648 that are somewhat similar to the corresponding components described above and illustrated in Figures 15J and 15K.

[00395] In this design, the redirector mover 1648 again includes a redirector actuator assembly 1648a, a guide assembly 1648b, and a redirector base 1648d that are similar to the corresponding components described above. However, in Figure 16, the guide assembly 1648b is a cartwheel style flexure that includes webbings that are filled with vibration damping mechanisms, e.g., membranes 1648ba that are filled with engineering viscoelastic damping material (vibration dampening material) that dampens vibration.

[00396] For example, one or all of the membranes 1648b can include a first material 1649a (e.g., a viscoelastic damping material) that surround a second material 1649b (e.g., a relatively stiff plug). With this design, the materials 1649a, 1649b have different properties that can be tuned to achieve the desired level of vibration damping. Alternatively, one or more of the membranes 1648ba can be made from a single material.

[00397] Additionally, or alternatively, the drive circuit (e.g., in the system controller 36, illustrated in Figure 1 ) for the redirector actuator assembly 1648a can include a low pass filter in electronics to reduce sensitivity to electrical noise near the natural frequency of the flexures of the guide assembly 1648b.

[00398] Figure 17 is a simplified side view of a portion of the mounting base 1764ba and yet another implementation of the redirector assembly 1722 including the redirector 1746, and the redirector mover 1748 that are somewhat similar to the corresponding components described above and illustrated in Figures 15J and 15K.

[00399] In one implementation, the redirector base 1748d is secured to the mounting base 1764ba with a dampening membrane 1776 there between. With this design, the dampening membrane 1776 inhibits and attenuates vibration from being transferred between the redirector base 1748d and the mounting base 1764ba. As a result thereof, vibration in the package will not adversely influence the position of the redirector 1646. In this design, the dampening membrane 1776 isolates the mounting base 1564ba (illustrated in Figure 15P) and the redirector mover 1648 from each other.

[00400] Figure 18 is a simplified perspective view of a portion of the mounting base 1864ba and yet another implementation of the redirector assembly 1822 including the redirector 1846, and the redirector mover 1848 that are somewhat similar to the corresponding components described above and illustrated in Figures 15J and 15K.

[00401] In one implementation, the redirector assembly 1822 additionally includes a magnet assembly 1878 positioned near the redirector actuator assembly 1848a and the guide assembly 1848b to dampen vibration. In this implementation, the magnet assembly 1878 provides eddy current damping of vibration. [00402] Figure 19 is a top perspective view of a portion of another implementation of the laser assembly 1910 without the outer frame top 1562b (illustrated in Figure 15A), and without the inner frame top 1564c (illustrated in Figure 15B). In this implementation, the laser assembly 1910 is fiber coupled, and includes a laser frame 1914, an emitter 1916, an emitter lens 1918, a transmission grating assembly 1920, a redirector assembly 1922, a beam shaper 1924, a beam director assembly 1966, an optical isolator 1926, a polarization adjuster assembly 1930, a pointer adjuster assembly 1928, a coupling lens assembly 1932, an optical fiber assembly 1934, and a non-linear crystal 1980 having a waveguide. For example, the non-linear crystal can be a second harmonic generator 1980. The waveguide includes coated facets, and in alternative examples, the waveguide has an effective area of at least 3, 4, or 5 microns, with good efficiency.

[00403] In Figure 19, the laser assembly 1910 and components are generally similar to the design described above and illustrated in Figures 15A-15S. However, the implementation illustrated in Figure 19 is designed to be tuned to generate an output beam having a different spectral range than the laser assembly 1510 illustrated above. As provided herein, the same, double walled laser frame 1914, and laser cavity layout can be used for different lasers.

[00404] In one non-exclusive example, it is desired that the laser assembly 1910 has an output beam that is tunable to have a wavelength in the five hundred to six hundred and thirty nanometer (500-630 nm) wavelength range. Currently, there are no emitters 1916 that directly emit in that wavelength range. Thus, the implementation of Figure 19 utilizes the second harmonic generator 1980 to achieve that range. In this example, if the second harmonic generator 1980 is a wavelength divided by two (A/2) generator, the emitter 1916 can be selected that generates light in the 1000-1260 nanometer range.

[00405] With this design, the emitter 1916, the emitter lens 1918, the transmission grating assembly 1920, the redirector assembly 1922, the beam shaper 1924, the beam director assembly 1966, the optical isolator 1926, the polarization adjuster assembly 1930, the pointer adjuster assembly 1928, the coupling lens assembly 1932, and the optical fiber assembly 1934 are somewhat similar to the corresponding components described above. However, these components are selected and/or designed to operate in the new operational range. Further, the emitter flex circuit 1916a can be selected to match the emitter 1916. [00406] Further, it should be noted that although the redirector assembly 1922 is similar to the design above, its mounting location on the mounting base 1964ba is different so that the redirector 1946 is properly positioned for mode-hope free wavelength tuning.

[00407] Moreover, in one non-exclusive design, the optical isolator 1926 can be designed to function at the wavelength of the second harmonic generator 1980 instead of the wavelength of the emitter 1916 because this wavelength may be more likely to be reflected back upstream.

[00408] In the implementation of Figure 19, the coupling lens assembly 1932 directs the beam into the second harmonic generator 1980. Further, the optical fiber assembly 1934 can include a fiber ferrule block 1934e that retains the fiber inlet facet 1934a.

[00409] The design of the non-linear crystal 1980 can be varied pursuant to the teachings provided herein. In one, non-exclusive example, the non-linear crystal 1980 is a second harmonic generator that divides the input wavelength by two. In Figure 19, the second harmonic generator 1980 includes a generator body 1980a having (i) an inlet generator facet 1980b that faces the coupling lens assembly 1932 and receives light focused from the coupling lens assembly 1932, and (ii) an outlet generator facet 1980c that faces the fiber inlet facet 1934a and directs light into the fiber inlet facet 1934a. As a non-exclusive example, one or both generator facets 1980b, 1980c can be angled so that any reflected light is directed to a light absorber (e.g., to the second light trap 1570b illustrated in Figure 15G) to inhibit any light reflected from the generator facets 1980b, 1980c from being directed back into the laser cavity.

[00410] In one implementation, the generator body 1980a generates the second harmonic frequency which is A/2 of a fundamental frequency on the laser cavity. Unfortunately, a small portion of the fundamental frequency may not be converted by the generator body 1980a. Thus, in certain designs, a thin film filter 1935 can be used to reflect the fundamental frequency to a light absorber (e.g., to the second light trap 1570b illustrated in Figure 15G).

[00411] Alternatively or additionally, the length of the optical fiber assembly 1934 can be selected to attenuate the fundamental wavelength.

[00412] Still alternatively or additionally, the filtering of the fundamental wavelength can also be done in free-space with dielectric filters. [00413] In one non-exclusive implementation, the laser assembly 1910 includes a filter (not shown in Figure 19) that transmits the second harmonic frequency, and blocks (reflects) the fundamental wavelength. For example, the filter can be positioned between the second harmonic generator 1980 and the fiber inlet facet 1934a. Further, the filter can be designed to direct the fundamental wavelength to a beam trap, or to another device that uses this light, e.g., a second output from the laser assembly 1910.

[00414] In one design, the light exiting the outlet generator facet 1980c of the second harmonic generator 1980 directly enters the fiber inlet facet 1934a. For example, the fiber inlet facet 1934a can be placed in very close proximity to the outlet generator facet 1980c so that most of the light from the outlet generator facer 1980c enters the fiber inlet facet 1934a. This arrangement can be referred to as a butt mount. In one, non-exclusive implementation, the fiber inlet facet 1934a is within one micron of the outlet generator facet 1980c without a lens therebetween. However, other spacings between the fiber inlet facet 1934a and the outlet generator facet 1980c are possible. As non-exclusive examples, the fiber inlet facet 1934a is within 1 -10 microns of the outlet generator facet 1980c without a lens therebetween. In one implementation, the fiber inlet facet 1934a is within 100 microns of the outlet generator facet 1980c without a lens therebetween.

[00415] In certain implementations, the second harmonic generator 1980 has high intrinsic efficiency, compact SHG waveguide which enables higher output power or longer ECDL lifetime by running at lower current. This generator 1980 is small, efficient, gets more light out, and less heat generation. In certain implementations, the second harmonic generator 1980 includes a waveguide having a small cross-sectional area versus a bulk crystal. Generally, the higher the intensity, the conversion.

[00416] As provided herein, the accurate operation of the second harmonic generator 1980 is temperature sensitive. In one, non-exclusive implementation, a single temperature sensor 1914cb (illustrated as a box) (e.g., a thermistor) is positioned near the second harmonic generator 1980 that provides feedback for closed loop control of the thermoelectric cooler 1514ca (illustrated in Figure 15B). With this design, the entire inner frame 1964 and the components mounted thereto can maintained at the desired temperature for successful operation the second harmonic generator 1980. Stated differently, the entire cavity can be built to be operated at the same temperature as the desired temperature of the second harmonic generator 1980. [00417] Alternatively, the single temperature sensor 1914cb, can be positioned at another location, (e.g., approximately half way between the emitter 1916 and the second harmonic generator 1980.

[00418] In certain implementations, the second harmonic generator 1980 allows for the emitter 1916 to be operated at a much lower power, while still having the same output power as compared to a bulk crystal. This extends the lifetime of the emitter 1916, and generally increases the available second harmonic generator 1980 power.

[00419] In one design, the laser cavity would have single-resonant frequency. The pump wavelength resonates but the second harmonic generator wavelength does not. It transmits through the cavity output coupler. This wavelength-dependent output coupling is nontrivial for a grating external cavity diode laser. One manifestation of this is to make the grating coating anti-reflective (AR) for the transmission grating assembly 1920, and highly reflective (HR) at the second harmonic generator 1980, ensuring the second harmonic generator 1980 avoids the grating surface entirely. In one design, the pump wavelength of the emitter 1916 resonates in the laser cavity but the wavelength of the second harmonic generator 1980 does not. The second harmonic wavelength transmits through the cavity output coupler. This is called a “singly resonant cavity.” This wavelength-dependent output coupling is nontrivial for a grating of an external cavity diode laser. One manifestation of this is to make the grating coating highly transmissive at the pump wavelength and highly reflective at the second-harmonic wavelength, ensuring the second-harmonic light avoids the grating surface entirely.

[00420] Figure 20 is a top perspective view of a portion of still another implementation of the laser assembly 2010 without the outer frame top 1562b (illustrated in Figure 15A), and without the inner frame top 1564c (illustrated in Figure 15B). In this implementation, the laser assembly 2010 is a free space laser (not fiber coupled), and includes a laser frame 2014, an emitter 2016, an emitter lens 2018, a transmission grating assembly 2020, a redirector assembly 2022, a beam shaper 2024, a beam director assembly 2066, an optical isolator 2026, a polarization adjuster assembly 2030, a pointer adjuster assembly 2028, a coupling lens assembly 2032, a second harmonic generator 2080, a beam collimator assembly 2082, and a filter 2084.

[00421] In Figure 20, the laser assembly 2010 and components are generally similar to the design described above and illustrated in Figure 19. However, the implementation illustrated in Figure 20 is designed so that the output beam is launched into free space. As provided herein, the same, double walled laser frame 2014, and laser cavity layout can be used for different types of lasers.

[00422] In one non-exclusive example, the light that exits the second harmonic generator 2080 is collimated with the beam collimator assembly 2082, and directed at the filter 2084 which can reflect the fundamental frequency and direct the fundamental frequency at the second light trap 1570b (illustrated in Figure 15G) or to another location. In this design, the light that is transmitted through the filter 2084 is directed through a window 2065 in the inner frame 2064 and through the outer frame aperture 2062aa in the outer frame 2062, and launched into free space. In this design, the window 2065 is use to hermetically seal the inner frame 2064.

[00423] Figure 21 is a top perspective view of a portion of yet another implementation of the laser assembly 2110 without the outer frame top 1562b (illustrated in Figure 15A), and without the inner frame top 1564c (illustrated in Figure 15B). In this implementation, the laser assembly 2110 is a free space laser (not fiber coupled), and includes a laser frame 2114, an emitter 2116, an emitter lens 2118, a transmission grating assembly 2120, a redirector assembly 2122, a beam shaper 2124, a beam director assembly 2166, an optical isolator 2126, a polarization adjuster assembly 2130.

[00424] In Figure 21 , the laser assembly 2110 and components are generally similar to the design described above and illustrated in Figures 15A-15H. However, the implementation illustrated in Figure 21 is designed so that the output beam is launched into free space. As provided herein, the same, double walled laser frame 21 14, and laser cavity layout can be used for different types of lasers.

[00425] In one non-exclusive example, the light that exits the polarization adjuster assembly 2130 is directed through the window 2165 in the inner frame 2164 and through the outer frame aperture 2162aa in the outer frame 2162, and launched into free space.

[00426] Figures 22A and 22B are alternative top perspective views of a portion of yet another implementation of the laser assembly 2210. More specifically, Figures 22A and 22B illustrate a portion of the laser frame 2214, including a portion of the outer frame 2262, and a portion of the inner frame 2264.

[00427] Additionally, Figures 22A and 22B illustrate that the laser assembly 2210 can additionally include an emissions attenuator 2281 that attenuates radiofrequency emissions from the outside (ambient) surrounding environment from entering the laser assembly 2210, to inhibit coupling onto the current directed to the emitter 1516 (illustrated in Figure 15D), and inhibit coupling to the actuator circuits which control the redirector actuator assembly 1548a (illustrated in Figure 15G) which control the wavelength of the emitter 1516. In the non-exclusive implementation of Figures 22A and 22B, the emissions attenuator 2281 is a tube (e.g., a metal tube) that extends from the outer frame 2262 towards the inner frame 2264. In this design, the emissions attenuator 2281 is fixedly secured to the outer frame 2262 and cantilevers towards the inner frame 2264.

[00428] With this design, in the fiber coupled designs, the optical fiber assembly 1534 (illustrated in Figure 15A) extends through an inner diameter 2281a of the emissions attenuator 2281 . Alternatively, in designs where the beam is launched into free space, the beam exiting the inner frame 2264 is directed through the inner diameter 2281 a of the emissions attenuator 2281. In both implementations, the emissions attenuator 2281 attenuates radiofrequency emissions, and inhibits these emissions from entering the inner frame 2264 and the components therein.

[00429] Figure 23 is a perspective view of a portion of still another implementation of the laser assembly 2310, including an emitter 2316, an emitter lens 2318, a transmission grating assembly 2320, a redirector assembly 2322, a beam shaper 2324, a beam director assembly 2366, an optical isolator 2326, a polarization adjuster assembly 2330, a pointer adjuster assembly 2328, a coupling lens assembly 2332, and an optical fiber assembly 2334 that are somewhat similar to the corresponding components described above and illustrated in Figure 15G.

[00430] However, in Figure 23 the fiber mount 2334d for the optical fiber assembly 2332 is slightly different. In this design, the fiber mount 2334d again includes a first mount 2334da that secures the optical fiber assembly 2334 to the inner frame 1564 (illustrated in Figure 15F) and a second mount 2334db that secures the fiber tip to the mounting base 1564ba (illustrated in Figure 15F). In this design, (i) the optical fiber assembly 2334 extends through the wall opening 1564bba (illustrated in Figure 15E), (ii) the first mount 2334da is generally tubular bushing shaped, has an outer diameter that is secured (e.g. with an adhesive) to the inner frame 1564, and an inner diameter that receives and is secured (e.g. with an adhesive) to the optical fiber assembly 2334; and (iii) the second mount 1534db is an “L” shaped bracket that secures the fiber tip to the mounting base 1564ba. However, other mounting arrangements are possible. [00431] In this design, when the fiber inlet facet 2334a is properly positioned, the fiber mount 2334d can be fixedly attached (e.g., via ultra-violet cured glue).

[00432] Additionally, Figure 23 illustrates that the optical fiber assembly 2334 can include a fiber cover made of a material (e.g., a metal shield or other material of suitable thickness) that attenuates radiated emissions from the outside (ambient) surrounding environment from entering the laser assembly 2310, to inhibit coupling onto the current directed to the emitter 1516 (illustrated in Figure 15D), and inhibit coupling to the actuator circuits which control the redirector actuator assembly 1548a (illustrated in Figure 15G) which control the wavelength of the emitter 1516. This allows for a more stable laser assembly 2310.

[00433] Figure 24 is a top perspective view of a portion of yet another implementation of the laser assembly 2410 without the frame top 1564c (illustrated in Figure 15B). It should be noted that this design can be implemented in a single or double frame configuration. In Figure 24, the laser assembly 2410 is a free space laser (not fiber coupled), and includes a laser frame 2414, an emitter 2416, an emitter lens 2418, a transmission grating assembly 2420, a redirector assembly 2422, a beam shaper 2424, a beam director assembly 2466, an optical isolator 2426, a polarization adjuster assembly 2430, a pointer adjuster assembly 2428, a coupling lens assembly 2432, an amplifier 2486, and a beam collimator assembly 2482.

[00434] In Figure 24, the laser assembly 2410 and components are generally similar to the design described above and illustrated in Figure 20. However, in the implementation illustrated in Figure 24, the laser assembly 2410 includes the amplifier 2486 instead of the non-linear crystal 2080 (illustrated in Figure 20). In Figure 24, the amplifier 2486 is positioned between the coupling lens assembly 2432 and the beam collimator assembly 2482. Alternatively, the laser assembly 2410 can be designed to include the second harmonic generator 2080 in addition to the amplifier 2486

[00435] The design of the amplifier 2482 can be varied to suit the design requirements of the laser assembly 2410. As non-exclusive examples, the amplifier 2482 can be a tapered amplifier or a semiconductor amplifier. Further, as nonexclusive examples, the amplifier 2482 can be designed to amplify the beam at least approximately 0.5, 1x, 10x, 100x, or 1000x.

[00436] In one non-exclusive example, the light that exits the amplifier 2482 is collimated with the beam collimator assembly 2482. In this design, the light that exits the beam collimator assembly 2482 is directed through a window 2465, and launched into free space. In this design, the window 2465 is use to hermetically seal the frame 2414. Alternatively, the laser assembly 2410 of Figure 24 can be designed to be fiber coupled.

[00437] Figure 25A is a simplified top view of a portion of a frame 2514, and an element assembly 2522 and can be used in any of the laser assembly designs provided herein, or in another type of system. In this design, the element assembly 2522 includes an optical element 2546 and an element mover assembly 2548 that is uniquely designed to accurately position the optical element 2546 relative to the frame 2514 or another component, with a relatively large range of motion, while having a relatively small footprint.

[00438] The design of the optical element 2546 can be varied. For example, the optical element 2546 can be a redirector 46 (illustrated in Figure 1 ), a lens, a grating, or another type of optical element. In a specific, non-exclusive example, the optical element 2546 is a redirector 46, and the element mover assembly 2548 (redirector mover) can accurately position (e.g., rotate) the redirector 46 relative to the transmission grating assembly 20 (illustrated in Figure 1 ) to selectively tune the laser assembly 10. In this implementation, the element mover assembly 2548 is designed to accurately position the redirector 46 relative to the frame 2514 with a relatively large range of motion, while having a relatively small footprint. As a result thereof, the laser assembly 10 can be selectively tuned over a larger spectral range in a mode-hop free fashion.

[00439] In one, non-exclusive implementation, the element mover assembly 2548 precisely moves the optical element 2546 in a closed loop fashion about a selected pivot axis 2554. In certain implementations, the selected pivot axis 2554 is chosen because movement of the optical element 2546 about that axis inhibits mode hops during the tuning of the center wavelength. It should be noted that the element mover assembly 2548 can be coupled to the frame 2514 similar to the fashion described above in reference to Figure 8 to properly position the selected pivot axis 2554.

[00440] The design of the element mover assembly 2548 can be varied pursuant to the teachings provided herein. In the non-exclusive implementation of Figure 25A, the element mover assembly 2548 includes an element actuator assembly 2548a, and a guide assembly 2548b. [00441] The design of the guide assembly 2548b can be varied pursuant to the teaching provided herein. As non-exclusive examples, the guide assembly 2548b can include one or more (i) flexure(s); (ii) bearing(s); and/or (iii) other rotary guide(s). In the non-exclusive implementation of Figure 25A, the guide assembly 2548b is a flexure that guides movement (e.g., rotation) of the optical element 2546. In this design, the guide assembly 2548b includes (i) a first guide side 2548ba that is secured to the frame 2514; (ii) a second guide side 2548bb that is spaced apart from the first guide side 2548ba, the second guide side 2548bb being coupled to the optical element 2546; and (iii) a plurality of guide connectors 2548bc that connect the guide sides 2548ba, 2548bb. In this design, the guide connectors 2548bc are arranged in a butterfly type arrangement. Alternatively, the guide assembly 2548b can have a configuration different than is illustrated in Figure 25A. In certain designs, the flexure 2548b is relatively stiff.

[00442] It should be noted that the guide assembly 2548b provided herein can achieve the required movement, with very little parasitic shift. As alternative, nonexclusive examples, the guide assembly 2548b provided herein can have a parasitic shift of less than approximately 15, 20, 25, 30, 40, 50, or 200 nanometers during the required element movement.

[00443] In the implementation of Figure 25A, the element actuator assembly 2548a selectively applies a force to the second guide side 2548bb to selectively move the second guide side 2548bb, deflect the guide assembly 2548b and pivot the optical element 2546. The element actuator assembly 2548a can be controlled by the system controller 36 (illustrated in Figure 1) to precisely move the optical element 2546.

[00444] The design of the element actuator assembly 2548a can be varied pursuant to the teaching provided herein. In Figure 25A, the element actuator assembly 2548a includes an actuator 2548aa, a lever assembly 2548ab that provides a mechanical advantage to the actuator 2548aa, and a sensor assembly (not shown in Figure 25A) for providing closed loop control of the actuator 2548aa. In the nonexclusive design of Figure 25A, the lever assembly 2548ab converts a relatively small movement by the actuator 2548aa to a relatively large displacement of the optical element 2546.

[00445] As non-exclusive examples, the actuator 2548a can include one or more (i) piezoelectric actuator(s), such as shear piezos (e.g., bidirectional, passive or active running), and/or piezo clips; (ii) bimetallic strip(s); (iii) thermoelectric cooler(s); (iv) heater(s), (v) voice coil (s), (vi) stepper motor(s), (vii) solenoid(s), (viii) electrostriction, (ix) motor(s), and/or (x) actuator(s). In the implementation of Figure 25A, because of the lever assembly 2548ab, the actuator 2548aa can be a linear piezoelectric stack having a relatively small footprint and a relatively short stroke, while still achieving the desired level of movement of the optical element 2546.

[00446] The amount of movement (“required element movement”) of the optical element 2546 required to tune the laser assembly over the desired spectral range will depend on many factors, including the design of the laser cavity, the design of the lever assembly 2548ab, and the desired spectral range. In alternative, non-exclusive designs, the required element movement is less than approximately 0.1 , 0.5, 1. 2, 5, or 10 degrees rotation about the selected pivot axis 2554 during tuning over the desired spectral range. However, other values are possible.

[00447] The lever assembly 2548ab converts the movement by the actuator 2548aa to deformation of the guide assembly 2548b and movement of the optical element 2546. In one implementation, the lever assembly 2548ab includes a rigid lever arm 2548ac that couples the actuator 2548aa to the guide assembly 2548b, and a lever pivot 2548ad that pivotably couples the lever arm 2548ac to the frame 2514, and allows for pivoting of the lever arm 2548ac about a lever pivot axis 2557. For example, the lever pivot 2548ad include one or more (i) flexure(s); (ii) bearing(s); and/or (iii) other rotary guide(s). In one implementation, the lever pivot axis 2557 is parallel to the selected pivot axis 2554 of the guide assembly 2548b.

[00448] The lever arm 2548ac provides mechanical advantage to the actuator 2548aa. In the implementation of Figure 25A, the lever arm 2548ac has (i) an input arm length “LI” that is defined by the distance between the lever pivot axis 2557 and where the actuator 2548aa engages the lever arm 2548ac, (ii) an output arm length L2 that is defined by the distance between the lever pivot axis 2557 and where the lever arm 2548ac engages the guide assembly 2548b. In the implementation of Figure 25A, the output arm length L2 is greater than the input arm length L1. It should be noted that the output arm length L2 and the input arm length L1 can be adjusted to achieve the desired mechanical advantage and compact design. As non-exclusive examples, the lever arm 2528ac can be designed to have a ratio L2/L1 of at least approximately 1 .2, 2, 5, 10, 15, or 20. Stated differently, in alternative non-exclusive examples, the output arm length is 1 .2, 2, 5, 10, 15 or 20 times longer than the input arm length. [00449] In the implementation of Figure 25A, the lever assembly 2548ab additionally includes a coupler assembly 2559 that couples and connects lever arm 2548ac to the guide assembly 2548b. Figure 25A also includes an arrow labeled F that illustrates the initial force vector on the guide assembly 2548b from the lever arm 2548ac. At this time, the force vector F is normal to an arc of the motion 2561 of the guide assembly 2548b. Unfortunately, as the guide assembly 2548b is deflected, the force vector F will become non-tangential to the arc of the motion 2561 of the guide assembly 2548b. This can lead to an undesirable shift in the pivot axis 2554 of the guide assembly 2548b during a large movemen.

[00450] Figure 25B is a simplified top view of the guide assembly 2548b of Figure 25A, including (i) the first guide side 2548ba; (ii) the second guide side 2548bb; and (iii) the plurality of guide connectors 2548bc that connect the guide sides 2548ba, 2548bb.

[00451] Figure 26 is a simplified top view of a portion of a frame 2614, and an element assembly 2622 that can be used in any of the laser assembly designs provided herein, or in another type of system. In this design, the element assembly 2622 is similar to the design described above and illustrated in Figure 25A. However, the design of Figure 26 includes an improved coupler assembly 2659 that couples and connects lever arm 2648ac to the guide assembly 2648b while de-coupling any non- tangential force vector from the lever arm 2648ac. In one non-exclusive implementation, the coupler assembly 2659 can include a point contact 2659a (e.g., a ball or other wedge), and a flat contact 2659b. In this design, the point contact 2659a engaging the flat contact 2659b allows for the transfer of tangential force and inhibits the transfer of non-tangential force. As a result thereof, this will inhibit the lever arm 2648ac from generating any undesirable shift in the pivot axis 2654 of the guide assembly 2648b. This will lead to pure rotation about the pivot axis 2654 and modehop free tuning during large movements.

[00452] In Figure 26, the point contact 2659a is attached to the guide assembly 2648b and the flat surface 2659b is part of the lever arm 2648ac. Alternatively, the point contact 2659a can be attached to the lever arm 2648ac, and the flat surface 2659b can be part of the guide assembly 2648b.

[00453] Figure 27 is a simplified top view of a portion of a frame 2714, and another implementation of an element assembly 2722 that can be used in any of the laser assembly designs provided herein, or in another type of system. In this design, the element assembly 2722 is somewhat similar to the design described above and illustrated in Figure 25A. However, the design of Figure 27 includes an improved coupler assembly 2759 that couples and connects lever arm 2748ac to the guide assembly 2748b while de-coupling any non-tangential force vector from the lever arm 2748ac. In one non-exclusive implementation, the coupler assembly 2759 can include a flexure mechanism that allows for the transfer of tangential force and inhibits the transfer of non-tangential force. As a result thereof, this will inhibit the lever arm 2748ac from generating any undesirable shift in the pivot axis 2754 of the guide assembly 2748b. This will lead to more pure rotation about the pivot axis 2754 and mode-hop free tuning.

[00454] It should be noted that in the non-exclusive implementation of Figure 27, the lever pivot 2748ad is a flexure, and the element actuator 2748aa is coupled to the lever arm 2748ac with a flexure 2749.

[00455] Figure 28A is a top perspective view of yet another implementation of the laser assembly 2810 with the laser frame 2814, including the frame top 2864c. As an overview, the laser assembly 2810 is uniquely designed to have a small form factor. More specifically, as illustrated in Figure 28A, the laser frame 2814 is designed to have a relatively small frame length 2814L, frame width 2814W, and frame height 2814H. In one specific example, the laser frame 2814 has a frame length 2814L of less than approximately thirty millimeters, a frame width 2814W of less than approximately 12.7 millimeters, and a frame height 2814H of less than approximately one millimeter.

[00456] In implementation of Figure 28A, the laser assembly 2810 is butterfly package and can be hermetically sealed.

[00457] Figure 28B is a top view of the laser assembly 2810 of Figure 28A without the frame top 2864c (illustrated in Figure 28A). In this implementation, the laser assembly 2810 is a fiber coupled laser. Alternatively, the laser assembly 2810 can be designed to launch the light into free space laser (not fiber coupled).

[00458] In the implementation of Figure 28B, the laser assembly 2810 includes a laser frame 2814, an emitter 2816, an emitter lens 2818, a transmission grating assembly 2820, a redirector assembly 2822, a coupling lens assembly 2832, and an optical fiber assembly 2834 that are somewhat similar to the corresponding components described above and illustrated in Figure 19. However, in the design of Figure 28A and 28B, each these components have been miniaturized. This reduces the cost of many of these components and the overall form factor. [00459] In one implementation of Figure 28B, the emitter 2816 is a chip on a submount. This allows for a smaller emitter 2816 and a smaller emitter beam. As alternative, non-exclusive examples, the emitter 2816 can have a length of less than approximately 1 , 2 or 3 millimeters.

[00460] Further, because the emitter beam is smaller, the emitter lens 2818, the transmission grating assembly 2820, the redirector assembly 2822, the coupling lens assembly 2832 can all be smaller. For example, the emitter lens 2818 can be positioned closer to the output facet of the emitter 2816. This allows for a smaller lens and a smaller beam. This also allows for a smaller form factor for the laser assembly 2810. For example, the emitter lens 2818 can be a microlens (e.g., 0.5 millimeters or less), and the transmission grating 2820 can be a micro grating (e.g., a grating thickness of less than ten millimeters). Generally, cost is a function of size.

[00461] Moreover, the transmission grating 2820 can be formed on a wafer. This further reduces the cost to make the transmission grating 2820. Further, with the smaller beam size, the size of the transmission grating 2820 can also be reduced. As non-exclusive examples, the transmission grating 2820 can have a grating thickness of less than 10, 15, 20, 25, or 30 millimeters. This reduces the cost for the material of the transmission grating 2820.

[00462] Additionally, the laser assembly 2810 can include a temperature sensor 2875, e.g., a thermistor.

[00463] Figure 29 is a top view of another implementation of a laser assembly 2910 without the frame top 2864c (illustrated in Figure 28A). In this implementation, the laser assembly 2910 is a fiber coupled laser. Alternatively, the laser assembly 2910 can be designed to launch the light into free space laser (not fiber coupled).

[00464] In the implementation of Figure 29, the laser assembly 2910 includes a laser frame 2914, an emitter 2916, an emitter lens 2918, a transmission grating assembly 2920, a redirector assembly 2922, a coupling lens assembly 2932, and an optical fiber assembly 2934 that are somewhat similar to the corresponding components described above and illustrated in Figure 28B. In this design, each these components have been miniaturized. This reduces the cost of many of these components.

[00465] Moreover, in the implementation of Figure 29, the laser assembly 2910 includes a non-linear crystal 2980 (e.g., a second harmonic generator) somewhat similar to the design in Figure 19 described above. However, in the design of Figure 29, the non-linear crystal 2980 has been miniaturized. Moreover, in Figure 29, the coupling lens assembly 2932 couples the light into the non-linear crystal 2980, and light from the non-linear crystal 2980 is coupled to the optical fiber assembly 2934.

[00466] Figure 30 is a top view of still another implementation of a laser assembly 3010 without the frame top 2864c (illustrated in Figure 28A). In this implementation, the laser assembly 3010 is a fiber coupled laser. Alternatively, the laser assembly 3010 can be designed to launch the light into free space laser (not fiber coupled).

[00467] In the implementation of Figure 30, the laser assembly 3010 includes a laser frame 3014, an emitter 3016, an emitter lens 3018, a transmission grating assembly 3020, a redirector assembly 3022, a coupling lens assembly 3032, and an optical fiber assembly 3034 that are somewhat similar to the corresponding components described above and illustrated in Figure 28B. In this design, each these components have been miniaturized. This reduces the cost of many of these components.

[00468] Moreover, in the implementation of Figure 30, the laser assembly 3010 includes (i) an isolator 3026 that somewhat similar to the design in Figure 15D described above, (ii) an amplifier 3086 that is somewhat similar to the design in Figure 24 described above, and (iii) a fiber coupler 3082 that couples light that exits the amplifier 3086 to the optical fiber assembly 3034. However, in the design of Figure

30, the isolator 3026, the amplifier 3086, and the fiber coupler 3082 have been miniaturized. Moreover, in Figure 30, the coupling lens assembly 3032 couples the light into the amplifier 3086, and light from the amplifier 3086 is coupled to the optical fiber assembly 3034. It should be noted that this design could be modified to include the second harmonic generator, if necessary.

[00469] While the particular designs as shown and disclosed herein is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

Claims

What is claimed is:

1. A laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam, the transmission grating assembly diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating assembly; and a redirector assembly that receives the second beam and directs a redirected beam at the transmission grating.

2. The laser assembly of claim 1 wherein the transmission grating assembly diffracts the redirected beam into a redirected cavity beam during transmission through the transmission grating assembly that is directed to the first facet of the emitter.

3. The laser assembly of any of claims 1 and 2 wherein the transmission grating assembly diffracts the redirected beam into a redirected output beam during transmission through the transmission grating assembly.

4. The laser assembly of claim 1 wherein the redirector assembly includes a redirector and a redirector mover that selectively moves the redirector to selectively tune a center wavelength of the emitter beam.

5. The laser assembly of claim 4 wherein the redirector mover includes a guide assembly that guides the movement of the redirector, and a redirector actuator assembly that moves the redirector.

6. The laser assembly of claim 5 further wherein the guide assembly includes a flexure.

7. The laser assembly of any of claims 5 and 6 wherein the redirector actuator assembly includes a piezoelectric actuator.

8. The laser assembly of claim 4 further wherein the redirector mover selectively moves the redirector approximately about a selected pivot axis that allows for mode hop free tuning over a large spectral range.

9. The laser assembly of claim 4 further comprising a system controller that selectively controls a current to the emitter to selectively tune the center wavelength of the emitter beam.

10. The laser assembly of claim 1 wherein the first beam is a zeroth order diffraction of the emitter beam, and the second beam is a first order diffraction of the emitter beam.

11 . The laser assembly of claim 1 wherein the emitter includes a second facet that forms a first cavity end of an external cavity, and the redirector assembly forms a second cavity end of the external cavity; and wherein the transmission grating is positioned the between cavity ends along an optical path of the external cavity and wherein the transmission grating functions as an output coupler.

12. The laser assembly of claim 1 wherein the redirector assembly includes a retroreflector or porro prism.

13. The laser assembly of claim 1 further comprising a beam shaper positioned in the path of the first beam that shapes the first beam.

14. The laser assembly of claim 1 further comprising an isolator positioned in the path of the first beam, wherein the isolator attenuates light from being directed back at the transmission grating.

15. The laser assembly of claim 1 further comprising a pointer adjuster assembly that adjusts the pointing of the first beam.

16. The laser assembly of claim 15 wherein the pointer adjuster assembly includes a first wedged window.

17. The laser assembly of claim 16 wherein the pointer adjuster assembly includes a second wedged window.

18. The laser assembly of claim 1 further comprising a polarization adjuster assembly that adjusts the polarization of the first beam.

19. The laser assembly of claim 18 wherein the polarization adjuster assembly includes a first waveplate.

20. The laser assembly of claim 19 wherein the polarization adjuster assembly includes a second waveplate.

21. The laser assembly of claim 1 further comprising a coupling lens assembly that focuses the first beam onto a lens focal point.

22. The laser assembly of claim 21 further comprising a lens actuator assembly that selectively moves the coupling lens to selectively adjust the lens focal point.

23. The laser assembly of claim 22 wherein the lens actuator assembly selectively moves the coupling lens along at least two axes.

24. The laser assembly of claim 1 further comprising an optical fiber assembly including a fiber inlet facet that receives the first beam.

25. The laser assembly of claim 24 further comprising a facet actuator assembly that selectively moves the fiber inlet facet to selectively adjust the position of the fiber inlet facet.

26. The laser assembly of claim 25 wherein the facet actuator assembly selectively moves the fiber inlet facet along at least two axes.

27. The laser assembly of claim 1 wherein the transmission grating includes a volume phase holographic grating.

28. The laser assembly of claim 1 wherein the transmission grating is a surface relief etched transmission grating.

29. The laser assembly of claim 1 wherein the transmission grating is a replica transmission grating.

30. The laser assembly of claim 1 wherein the transmission grating assembly includes a transmission grating positioned in the path of the emitter beam, wherein the transmission grating has a periodic structure that is aligned along a grating axis; and a grating mover assembly that selectively moves the transmission grating along the grating axis.

31. The laser assembly of claim 1 wherein the transmission grating assembly includes a transmission grating positioned in the path of the emitter beam, wherein the transmission grating has a periodic structure that is aligned along a grating axis and a transverse axis that is transverse to the grating axis; and wherein the transmission grating is rotatable about the transverse axis to adjust the diffraction experienced by the emitter beam.

32. The laser assembly of claim 1 wherein the transmission grating assembly includes a transmission grating positioned in the path of the emitter beam, wherein the transmission grating has a periodic structure that is aligned along a grating axis and a transverse axis that is transverse to the grating axis; and wherein the transmission grating is rotatable about the transverse axis to adjust a power ratio of the beams.

33. The laser assembly of claim 1 further comprising a second harmonic generator that receives the first beam and changes a frequency of the first beam.

34. The laser assembly of claim 1 further com prising a non-linear crystal that receives the first beam and changes a frequency of the first beam.

35. The laser assembly of claim 1 further comprising an amplifier that receives the first beam and amplifies the power of the first beam.

36. The laser assembly of claim 1 wherein the redirector assembly includes a redirector and a guide assembly, an actuator, and a lever arm that couples the guide assembly to the actuator.

37. The laser assembly of claim 1 wherein the emitter has an emitter length of less than two millimeters, and the transmission grating assembly includes a transmission grating having a grating thickness of less than twenty millimeters.

38. A laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating, the transmission grating having a periodic structure that is aligned along a grating axis; and a grating mover assembly that selectively moves the transmission grating along the grating axis.

39. The laser assembly of claim 38 further comprising a redirector that receives the second beam and directs a redirected beam at the transmission grating; wherein the redirector and transmission grating cause a gaussian shaped filter to the effective gain of the emitter, wherein a longitudinal mode of the emitter closest to the center of the filter will have the highest gain and lase; and wherein the grating mover assembly selectively moves the transmission grating along the grating axis to selectively adjust the longitudinal mode without shifting the filter.

40. The laser assembly of claim 39 wherein the grating mover assembly selectively moves the transmission grating along the grating axis to selectively position a desired longitudinal mode to the center of the filter.

41. The laser assembly of claim 38 wherein the grating mover assembly selectively moves the transmission grating along the grating axis to optimize the intensity of the first beam.

42. The laser assembly of claim 38 wherein the grating mover assembly selectively moves the transmission grating along the grating axis to reduce modulation of the optical power of the first beam while tuning of the laser assembly.

43. The laser assembly of claim 38 wherein the transmission grating includes a volume phase holographic grating.

44. A laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; and a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam during transmission through the transmission grating, the transmission grating being a having a periodic structure aligned along a grating axis and a transverse axis that is transverse to the grating axis; and wherein movement of the transmission grating about the transverse axis adjusts a diffraction experienced by the emitter beam.

45. The laser assembly of claim 44 wherein the transmission grating includes a volume phase holographic grating.

46. An external cavity laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating positioned in the path of the emitter beam, the transmission grating diffracting the emitter beam into the first beam and a second beam that are transmitted through the transmission grating; wherein the transmission grating includes a volume phase holographic grating; and a redirector that receives the second beam and redirects a redirected beam at the transmission grating.

47. A laser assembly that generates an output beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a redirector that directs a redirected beam back to the emitter to form an external cavity; a flexure that guides movement of the redirector; and a redirector actuator assembly that selectively bends the flexure to move and position the redirector to selectively change the path length of the external cavity.

48. The laser assembly of claim 47 wherein the flexure is (i) low stiffness in one degree of freedom, and (ii) high stiffness in the other five degrees of freedom.

49. The laser assembly of claim 48 wherein the flexure includes a vibration damping mechanism.

50. The laser assembly of claim 48 wherein the redirector actuator assembly includes wires, and the wires are attached to the mounting base to inhibit vibration.

51 . A laser assembly that generates an output beam that is coupled to an optical fiber having a fiber inlet facet, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; a coupling lens assembly that focuses the output beam onto the fiber inlet facet; and a pointer adjuster that adjusts the relative position between the output beam and the fiber inlet facet.

52. A laser assembly that generates an output beam that is coupled to an optical fiber having a fiber inlet facet, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; a coupling lens assembly that focuses the output beam onto the fiber inlet facet; and a polarization adjuster assembly that selectively adjusts a polarization of the output beam.

53. The laser assembly of claim 52 wherein a wedged window adjusted to adjust pointing.

54. The laser assembly of claim 52 wherein the coupling lens is selectively moved.

55. The laser assembly of claim 52 wherein the optical fiber inlet facet is selectively moved.

56. A beam adjuster assembly for adjusting an inlet beam with four degrees of freedom, the beam adjuster assembly comprising: an adjuster base; a first pointer adjuster that receives the inlet beam, the first pointer adjuster being a wedged shaped element; and a second pointer adjuster that receives the beam that exits the first pointer adjuster, the second pointer adjuster being a wedged shaped element; wherein the first pointer adjuster and the second pointer adjuster are selectively and independently rotated relative to the adjuster base to selectively adjust the pointing of the inlet beam wherein two degrees of freedom; and wherein the first pointer adjuster and the second pointer adjuster are selectively and independently tilted relative to the adjuster base to selectively adjust the translation of the inlet beam with two degrees of freedom.

57. The beam adjuster assembly of claim 56 wherein the adjuster base includes (i) a first receiver that is shaped to receive a portion of the first pointer adjuster, and (ii) a second receiver that is shaped to receive a portion of the second pointer adjuster; wherein at least one of the receivers is a socket that is shaped like a portion of a sphere.

58. The beam adjuster assembly of claim 57 wherein a least one of the pointer adjusters has a spherical shaped segment.

59. The beam adjuster assembly of claim 56 further comprising an adjuster faster that fixedly secures each pointer adjuster to the adjuster base.

60. A laser assembly that generates a laser beam, the laser assembly comprising: an emitter that emits a laser beam; a first frame that encircles the emitter; and a second frame that encircles the first frame and the emitter to thermally isolate the emitter from the surrounding environment and provide stable fluid space between the frames.

61 . The laser assembly of claim 60 wherein the first frame includes a first frame top having a thickness of at least two millimeters, and is made of a material having a relatively high thermal conductivity coefficient.

62. The laser assembly of claim 61 wherein the first frame includes side walls, and wherein the first frame top is hermetically sealed to the side walls.

63. The laser assembly of claim 61 wherein a space between the first frame and the second frame is between approximately one to two millimeters.

64. The laser assembly of claim 61 wherein a space between the first frame and the second frame is less than approximately fifty millimeters.

65. The laser assembly of claim 61 further comprising an emission attenuator that attenuates emissions, and extends from the second frame towards the first frame, the beam exiting the laser assembly is directed through an attenuator aperture in the emission attenuator.

66. A laser assembly that generates an output beam, the laser assembly comprising: an emitter that emits an emitter beam; an optical fiber assembly including a fiber cover made of a material that attenuates radiated electromagnetic emissions from the ambient from entering the laser assembly; and a coupling lens assembly that focuses the beam onto the fiber inlet facet.

67. A laser assembly that generates a laser beam, the laser assembly comprising: an emitter that emits a laser beam; a redirector that forms an external cavity with the emitter; a non-linear crystal that receives the beam exiting from the external cavity, wherein the non-linear crystal includes a waveguide.

68. The laser assembly of claim 67 wherein the non-linear crystal is a second harmonic generator.

69. The laser assembly of claim 67 wherein the second harmonic generator includes a waveguide with coated facets, and the waveguide has an effective area of at least three microns.

70. The laser assembly of claim 67 wherein the light exiting the second harmonic generator is butt-coupled to a fiber inlet facet of a fiber, wherein the separation distance output facet of the waveguide and the fiber inlet facet is than 100 microns.

71 . A laser assembly that generates an output beam that is coupled to an optical fiber having a fiber inlet facet, the laser assembly comprising: a laser frame; an emitter that emits an emitter beam, the emitter being positioned in the laser frame; and a transmission grating assembly positioned in the path of the emitter beam that generates a first beam that is transmitted through the transmission grating assembly; the transmission grating assembly being positioned in the laser frame; wherein the emitter and the transmission grating assembly can be changed to change the wavelength range of the output beam.

72. The laser assembly of claim 71 further comprising an emitter mount that couples the emitter to the laser frame, wherein the emitter mount has a geometry designed to selectively receive a different emitter on the emitter mount.

73. The laser assembly of claim 71 wherein the laser frame includes a mounting base and a pivot axis of the transmission grating can be moved and set relative to the mounting base for different emitters.

74. The laser assembly of claim 71 wherein the laser frame includes a mounting base and a pivot axis of the transmission grating can be moved and set relative to the mounting base for different emitters.

75. The laser assembly of claim 71 wherein the laser frame includes a first frame and a second frame that encircles the first frame.

76. The laser assembly of claim 71 further comprising a second harmonic generator.

77. The laser assembly of claim 76 further comprising an isolator that is set to the wavelength of the fundamental wavelength of the external cavity emitter wavelength.

78. A laser assembly that generates an output beam that is coupled to an optical fiber having a fiber inlet facet, the laser assembly comprising: a laser frame including a mounting base; an emitter that emits a beam, the emitter being coupled to the mounting base; and a polarization adjuster assembly that selectively adjusts a polarization of the beam; wherein the polarization adjuster assembly includes (i) a polarization adjuster that can be selectively moved relative to the mounting base to adjust the polarization, the polarization adjuster having anisotropic properties; (ii) an adjuster mount that is coupled to the mounting base; and (iii) a polarization adjuster fastener that couples the polarization adjuster to the adjuster mount.

79. The laser assembly of claim 78 wherein the polarization adjuster fastener is an adhesive.

80. The laser assembly of claim 78 wherein the polarization adjuster is a waveplate.

81 . The laser assembly of claim 78 wherein the polarization adjuster has a first coefficient of thermal expansion along a first axis, and a second coefficient of thermal expansion along a second axis, that is different from the first coefficient of thermal expansion.

82. The laser assembly of claim 81 wherein the second coefficient of thermal expansion can be greater than the first coefficient of thermal expansion.

83. The laser assembly of claim 81 wherein the second coefficient of thermal expansion is at least 10 percent greater than the first coefficient of thermal expansion.

84. The laser assembly of claim 81 wherein the first coefficient of thermal expansion along the first axis, approximately matches with a coefficient of thermal expansion for the mounting base and/or the adjuster mount.

85. The laser assembly of claim 84 wherein the polarization adjuster is mounted so that the first axis is substantially parallel with an upper surface of the mounting base.

86. The laser assembly of claim 85 wherein the adjuster fastener includes a spaced apart pair of adhesive spots that are aligned approximately along the first axis.

87. An element mover assembly that selectively moves an optical element relative to a frame, the element mover assembly comprising: a guide assembly that guides movement of the optical element, the guide assembly being coupled to the frame and the optical element; and an element actuator assembly that selectively moves the guide assembly and position of the optical element, the element actuator assembly including an element actuator, and a lever arm that pivots about a lever pivot axis, wherein the lever arm is coupled to the element actuator and the guide assembly, and wherein element actuator selectively pivots the lever arm about the lever pivot axis to selectively move the guide assembly and the optical element.

88. The element mover assembly of claim 87 wherein the guide assembly includes a flexure that is deformed during movement.

89. The element mover assembly of claim 88 wherein the flexure is a butterfly type flexure.

90. The element mover assembly of claim 87 wherein the lever arm includes (i) an input arm length that is defined by the distance between where the element actuator engages the lever arm and the lever pivot axis, and (ii) an output arm length that is defined by the distance between where the lever arm engages the guide assembly and the lever pivot axis; wherein the output arm length is greater than the input arm length.

91 . The element mover assembly of claim 90 wherein the output arm length is at least 1 .2 times greater than the input arm length.

92. The element mover assembly of claim 87 further comprising a coupler assembly that couples the lever arm to the guide assembly in a fashion such that non- tangential forces are inhibited from being imparted on the guide assembly by the lever arm.

93. The element mover assembly of claim 92 wherein the coupler assembly includes a coupler flexure.

94. The element mover assembly of claim 92 wherein the coupler assembly includes a point contact and flat.

95. A laser assembly including the element mover assembly of claim 87, an emitter that emits an emitter beam, and the optical element, wherein the optical element is a redirector that is moved by the element mover assembly to selectively tune the frequency of the emitter beam.

96. A laser assembly that generates a first beam, the laser assembly comprising: an emitter that emits an emitter beam from a first facet; and a diffraction grating positioned in the path of the emitter beam, the diffraction grating diffracting the emitter beam; wherein the diffraction grating has a diffraction efficiency which is dependent on an angle of incidence of the emitter beam on the diffraction grating, and wherein the diffraction grating is rotated in yaw to adjust the angle of incidence.

97. The laser assembly of claim 96 wherein the gratings has a diffraction efficiency which is strongly dependent on the angle of incidence.