WO2007149342A2

WO2007149342A2 - Tunable coherent light source

Info

Publication number: WO2007149342A2
Application number: PCT/US2007/014111
Authority: WO
Inventors: Jurgen Niederhofer
Original assignee: Newport Corporation
Priority date: 2006-06-16
Filing date: 2007-06-15
Publication date: 2007-12-27
Also published as: WO2007149342A3

Abstract

The present application is directed to a tunable coherent light source and includes at least one seed source configured to irradiate at least one seed signal, at least one modulator configured to modulate the seed signal to a desired pulse width and repetition rate, at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, at least one control unit in communication with at least one of the seed source, the modulator, and the organic laser system and configured to receive at least one input and generate a control signal, and at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a desired wavelength.

Description

TUNABLE COHERENT LIGHT SOURCE

By

Jϋrgen Niederhofer

Attorney Docket No.: 0029-300BRL-06 Drawings: Seven (7) sheets

Newport Corporation

Attn: Brian F. Swienton

1791 Deere Avenue

Irvine, CA 92606

TUNABLE COHERENT LIGHT SOURCE

BACKGROUND

[0001] Devices capable of emitting coherent radiation are used in a variety of applications. For example, these devices are commonly used in materials processing, therapeutic applications, and research. Conventional lasers are configured to emit radiation at a single wavelength. Increasingly, however, laser systems capable of emitting radiation at multiple wavelengths simultaneously are needed for a number of applications.

[0002] Tunable coherent lights sources are used in a variety of applications. For example, dye lasers may be configured to produce a coherent output at a number of discreet wavelengths by irradiating various organic dye materials positioned within the laser with a pump signal. During use, an organic dye within a liquid solution is flowed through a circulation circuit and irradiated with a pump signal generated by a laser, thereby producing a coherent output at a desired wavelength or within a narrow wavelength range. Thereafter, the user may replace the organic dye with any variety of other organic dyes to produce a desired output wavelength. While these devices have proven useful in the past, a number of shortcomings have been identified. Changing the dye material has proven to be a time consuming process as the circulation circuit and liquid reservoir containing the dye material must be flushed to prevent contamination. Further, optical components within the laser system may need to be inserted to provide a desired output wavelength. Also, in some applications, laser devices capable of output a number of coherent wavelengths simultaneously may be desired. For example, polychromatic or white light laser devices may be useful in medicine, spectroscopy, holography, photo-chemistry, isotope separation, spectrum analysis, optical measurement, and/or ultra-short light pulse generation. Multi-wavelength output spectrum cannot be generated simultaneously using these systems.

[0003] Thus, in light of the foregoing, these exists an ongoing need in the scientific community for the development of polychromatic or white light lasers. SUMMARY

[0004] Various embodiments of tunable coherent light sources are disclosed herein. In one embodiment, the present application is directed to a tunable coherent light source and includes at least one seed source configured to irradiate at least one seed signal, at least one modulator configured to modulate the seed signal to a desired pulse width and repetition rate, at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, at least one control unit in communication with at least one of the seed source, the modulator, and the organic laser system and configured to receive at least one input and generate a control signal, and at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a desired wavelength.

[0005] In an alternate embodiment, the present application is directed to a tunable coherent light source and includes at least one seed source configured to irradiate at least one seed signal, at least one modulator configured to modulate the seed signal to a desired pulse width and repetition rate, at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, the organic laser system comprising one or more laser chips comprised of a substrate having at least one spirofluorene derivative applied thereto, at least one control unit in communication with at least one of the seed source, the modulator, and the organic laser system and configured to receive at least one input and generate a control signal, and at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a desired wavelength. [0006] In another embodiment, the present application is directed to a tunable coherent light source and includes at least one seed source configured to irradiate at least one seed signal, at least one modulator configured to modulate the seed signal to a desired pulse width and repetition rate, at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, at least one control unit in communication with at least one of the seed source, the modulator,. and the organic laser system and configured to receive at least one input and generate a control signal, and at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a wavelength from about from about 350nm to about 840nm.

[0007] Other features and advantages of the embodiments of tunable coherent light sources as disclosed herein will become apparent from a consideration of the following detailed description.

[0008] Various devices for reducing the feedback within an optical waveguide will be explained in more detail by way of the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWNGS

[0009] Various tunable coherent light sources will be explained in more detail by way of the accompanying drawings, wherein:

[0010] Figure 1 shows a schematic diagram of an embodiment of a tunable coherent light source having an organic laser system positioned therein;

[0011] Figure 2 shows a schematic diagram of an embodiment of a seed source of a tunable coherent light source emitting a continuous wave signal to a modulator to produce a modulated seed signal;

[0012] Figure 3 shows an embodiment of a laser chip for use within an embodiment of and organic laser system of a tunable coherent light source;

[0013] Figure 4 shows a cross-sectional view of an embodiment of a laser chip for use in an embodiment of an organic laser system within a tunable coherent light source; [0014] Figure 5 shows a dye tuning curve for materials which may be applied to a substrate of a laser chip for use within an embodiment of a tunable coherent light source;

[0015] Figure 6 shows a schematic diagram of another embodiment of a tunable coherent light source having an organic laser system positioned therein and dye amplifier in optical communication therewith;

[0016] Figure 7 shows a schematic diagram of another embodiment of a tunable coherent light source having multiple organic laser system positioned therein; and

[0017] Figure 8 shows a schematic diagram of an embodiment of a tunable coherent light source having an optical element configured to separate the output of at least one organic laser into multiple discreet wavelength outputs.

DETAILED DESCRIPTION

[0018] Figure 1 shows an embodiment of a tunable coherent light source. As shown, the tunable coherent light source 10 includes at least one organic laser system 12 in optical communication with at least one pump or seed source 14. In the illustrated embodiment a single organic laser system 12 is in communication with a single seed source 14. In an alternate embodiment, a single organic laser system 12 is in communication with multiple seed laser sources 14. Optionally, multiple organic laser systems 12 may be in communication with a single seed source 14.

[0019] Referring again to Figure 1 , any variety of seed sources 14 may be used with the tunable coherent light source 10 disclosed herein. For example, in one embodiment the seed source 14 comprises at least one laser source configured to emit one or more optical signals at one or more wavelengths to the organic laser system 12. In one specific embodiment, the^' seed source 14 comprises a laser device configured to irradiate one or more laser signals having a wavelength from about 100nm to about 2000nm to the organic laser system 12. In an alternate embodiment, the seed source 14 is configured to irradiate light having a wavelength of about 100nm to about 370nm. For example, the seed source 14 may comprise a Vanguard^® laser manufactured by Spectra-Physics, Inc., configured to irradiate light at about 355nm to the organic laser system 12. Those skilled in the art will appreciate, however, any variety of laser sources may be used with the tunable coherent light source 10, including, without limitation, solid state laser, diode lasers, gas laser, disk lasers, fiber lasers, chemical lasers, and the like. Further, the seed source 14 may provide continuous wave emissions, quasi- continuous wave emissions, pulsed emissions, mode-locked emissions, and the like. As stated above, multiple seed sources 14 may be provided and configured to provide pump radiation to at least one organic laser system 12 included in or in optical communication with the tunable coherent light source 10.

[0020] As shown in Figure 1, the seed source 14 may be in communication with one or more power supplies 16 configured to provide power to the seed source 14. In one embodiment, the power supply 16 provides power to the seed source 14 via at least one seed power conduit 18. For example, the power supply 16 may be configured to provide an electrical current to the seed source 14 via the seed power conduit 18. In an alternate embodiment, the power supply 16 may be configured to provide power to the seed source without the use of a power conduit 18. For example, the power supply 16 may be configured to irradiate at least one optical signal to the seed source 14. Optionally, the power supply 16 may be configured to one or more RF and/or magnetic signals (Eddy currents) to the seed source 14. Optionally, the power supply 16 may be positioned within the seed source 14.

[0021] Referring again to Figure 1 , the power supply 16 may be configured to provide power to at feast one control unit 20 coupled to one or more devices within or associated with the tunable coherent light source 10. In the illustrate embodiment, the power supply 16 is in communication with the control unit 20 via a control unit power conduit 22. Like the seed source 14, the control unit 20 may be configured to receive power from the power supply 16 without a conduit. In an alternate embodiment, the control unit 20 may include an internal power supply and, thusly, may not require power from the power supply 16. The control unit 20 may be configured to provide one or more control signals to one or more components within or in communication with the tunable coherent light source 10. For example, the control unit 20 may be configured to provide control signals to various devices via one or more conduits coupled thereto. Optionally, the control unit 20 may be configured to provide control signals to one or more devices coupled thereto wirelessly. Any number and variety of devices may be used to form the control unit 20, including for example, microprocessors, computers, stage controllers, measuring devices, and the like.

[0022] As shown in Figure 1, one or more modulators 24 may be used with the tunable light source 10. The modulator 24 is configured to modulate the seed signal 26 emitted from the seed source 14. As shown in Figures 1 and 2, the modulator 24 may be in communication with the power supply 16 via at least one modulator power conduit 28 and configured to modulate the seed signal 26 to produce a modulated signal 30 having a desired pulse width and/or repetition rate. For example, in the illustrate embodiment the signal source 14 outputs a seed signal 26 (355nm, 12ps, 80 MHz). The modulator 24 modulates the signal an outputs a modulated signal 30 at a desired pulse width and/or repetition rate. In one embodiment, the modulator 24 may be in communication with at least one modulator controller 32 configured to generate one or more modulator control signals 34 thereby permitting a user to selectively control the modulator 24. For example, in one embodiment the modulator controller 32 is configured to output one or more RF modulator control signals 34. The modulator controller 32 may be configured to communicate with the modulator 24 via a conduit or, in the alternative, wirelessly. In an alternate embodiment, the modulator 24 may be in communication with the control unit 20, which may be configured to control the modulator 24. As such, the modulator controller 32 may be eliminated. Those skilled in the art will appreciate that any variety of modulators 24 may be used with the tunable coherent light source 10 including, without limitation, acousto-optic modulators, semiconductor saturable absorbing mirrors, q-switches, choppers, light valves, shutters, and the like. Further, the modulator 24 may be configured to provide any variety of pulse widths and repetition rates as desired by the user.

[0023] Referring again to Figure 1 , one or more optical elements 36 may be positioned within the tunable coherent light source 10. In the illustrated embodiment, a lens used to focus the modulated signal 30 into the organic laser system 12. Optionally, any variety of optical elements 36 may be used within the tunable coherent light source 10, including, for example, polarizers, wave plates, lenses, prisms, spatial filters, pinholes, optical crystals, mirrors, filters, measuring devices include power meters and beam profilers, gratings, etalons, and the like. Optionally, various optical elements 36 may be positioned at various locations within the tunable coherent light source 10. For example, a spatial filter and volume Bragg grating may be positioned proximate to the seed source 14, while a lens system may be used proximate to the organic laser system 12.

[0024] As shown in Figure 1, one or more organic laser systems 12 may be positioned within the tunable coherent light source 10. In the illustrate embodiment the organic laser system 12 is positioned on at least one controllable mount 38. As shown, the controllable mount 38 may be in communication with the control unit 20 via a control conduit 40. Optionally, the controllable mount 38 may be configured to communicate with the control unit 20 wirelessly. In another embodiment, the control unit 20 may be incorporated into the controllable mount 38. Exemplary controllable mounts 38 include one dimension stages and multiple dimension stages. For example, the controllable mount 38 may comprise a 2D translation stage capable of horizontal and vertical translation of the organic laser system 10. Further, the controllable mount 38 may be configured to provide precise movement on the order of 5nm increments. Those skilled in the art will appreciate that any variety and number of controllable mounts 38 may be used with the tunable coherent light source 10. Further, optionally, the controllable mount 38 may include one or more servo motors, linear motors, squiggle motors, piezo motors, and the like to effect movement of the organic laser system 10 mounted thereon.

[0025] Referring again to Figure 1, the organic laser system 10 includes at least one laser chip 42 configured to generate a tunable output 50. As shown in Figures 3 and 4, the laser chip 42 comprises a substrate 56 having one or more layers 58 deposited thereon. In one embodiment, the substrate comprises a distributed feedback grating, while the layers 58 deposited thereon comprise organic materials configured to emit coherent light at a desired wavelength when excited by the modulated signal 30. As such, the laser chip 42 may form a solid state optical element. For example, in one embodiment one or more thin film layers 58 of a spirobifluorene derivative deposited onto a Bragg grating substrate 56. Those skilled in the art will appreciate that any variety of organic materials may be applied to the substrate 56 to produce a laser chip 42 configured to provide a coherent output at a desired wavelength. Figure 5 shows a dye tuning curve for materials which may be applied as an organic layer 58 to the substrate 56. Further, the grating period G_p of the grating forming the substrate 56 may also be selected to provide a desired output wavelength. Those skilled in the art will appreciate that the substrate 56 may be manufactured using techniques known in the art. In another embodiment, the substrate further includes a volume Bragg grating architecture, thereby permitting an alternate wavelength selection capability.

[0026] As shown in Figure 1, the organic laser system 12 outputs at least one coherent signal at a desired wavelength. In one embodiment the wavelength of the output signal is from about 150nm to about 2000nm. In another embodiment, the wavelength of the output signal 50 is from about 355nm to about 840nm. In still another embodiment, the wavelength of the output beam is within the visible spectrum. Optionally, one or more additional optical elements 52 may be used to further condition or otherwise modify the output signal 50. Exemplary additional optical elements 52 include, without limitation, lenses, mirrors, filters, gratings, volume Bragg gratings, polarizers, prisms, measuring devices, optical crystals, second harmonic generation devices, third harmonic generation devices, harmonic generation devices, birefringent filters, and the like.

[0027] Referring again to Figure 1, the tunable coherent light source 10 may include one or more external interface devices 44. In one embodiment, the external interface 44 enables automated adjustments and control of various components of the tunable coherent light source 10 via the control unit 20. In another embodiment, the external interface 44 enables a user to control adjust and control of various components of the tunable coherent light source 10. As shown, the external interface 44 may be configured to couple to one or more user interface devices 46 via an interface conduit 48. Exemplary user interface devices 46 include, without limitation, computers, processors, keyboards, measuring devices, and the like. Optionally, the external interface 44 may be configured to communicate with the user interface 46 wirelessly, thereby eliminating the interface conduit 48.

[0028] As stated above, one or more additional optical elements may be used in conjunction with the tunable coherent light source 10. Figure 6 shows an embodiment of a tunable coherent light source 10 as described above having a dye amplifier 60 to further amplify or otherwise condition the output signal 50. Like the organic laser system 12, the dye amplifier 60 may include one or more laser chips 62 therein. Further, the dye amplifier may include organic dye materials. Optionally, the dye amplifier 60 may be positioned on a controllable mount (not shown) much like the organic laser system 12. Further, the controllable mount (not shown) may be in communication with one or more controllers, such as the control unit 20. Optionally, the dye amplifier 60 may be positioned within the tunable coherent light source 10. Optionally, one or more sensors or detectors 66 may be in optical communication with the tunable coherent light source 10 and configured to provide one or more sensor signals 68 to the control unit 20 in response thereto (See Figure 1). For example, the sensor 66 may be configured to determine the wavelength of the tunable output 50 and provide data to the control unit 20. In the illustrated embodiment, the sensor 66 is positioned external of the tunable coherent light source 10. Optionally, the sensor 66 may be positioned within the tunable coherent light source 10.

[0029] As stated above, the tunable coherent light source 10 disclosed herein may include any number of organic laser systems 12 and/or seed sources 14. Figure 7 shows an embodiment of a tunable coherent light source 110 having multiple organic laser systems 112A-112C positioned therein, each configured to receive a seed signal 126 from a seed source 114. As shown, the seed source 114, powered by the power supply 116 via a power conduit 118, outputs a seed signal 126. At least one modulator 124 modulates the seed signal 126, thereby providing a modulated signal 130. Optionally, multiple modulators 124 may be associated with individual organic laser systems 112A-112C, thereby providing a tunable coherent light source 110 capable of outputting multiple different outputs at varying wavelengths, repetition rates, and/or pulse widths.

[0030] Referring again to Figure 7, the modulated signal 130 may be split into multiple modulated signals using one or more optical elements 132A and 132B, such as beam splitters. Optical element 132A directs a portion of the incoming modulated signal 130 into organic laser system 112A and directs a portion of the modulated signal 130 to optical element 132B, which in turn directs a portion of the modulated signal into organic laser system 112B and directs a portion of the modulated signal 130 to optical element 132C. Optical element 132C, which may comprise a mirror, directs the remaining modulated signal 130 to organic laser system 112C. Like the previous embodiment, one or more additional optical elements 132D may be positioned at various locations within the tunable coherent light source as desired.

[0031] As shown in Figure 7, the tunable coherent light source 110 may one or more organic laser systems 112 therein. In the illustrated embodiment, three organic laser systems 112A-112C are used in the system. Like the previous embodiment, each organic laser system 112A-112C may include any number of laser chips 142. Further, each organic laser system 112A-112C may be positioned on a controllable stage as detailed in the previous embodiment. In the illustrated embodiment, organic laser system 112A includes laser chip 142A configured to output an output signal 150A at a first wavelength when excited by the modulated signal 130. Similarly, organic laser system 112B includes laser chip 142B configured to output an output signal 150B at a second wavelength when excited by the modulated signal 130, and organic laser system 112C includes laser chip 142C configured to output an output signal 150C at a third wavelength when excited by the modulated signal 130. In one embodiment, the wavelengths of the first, second, and third output signals 150A-150C are different. In an alternate embodiment, at least one of the wavelengths of the first, second, and third output signals 150A-150C are substantially the same as at least one other output signal.

[0032] As shown in Figure 7, the organic laser systems 112A-112C are in communication with at least one control unit 120 via a control conduit 128. Optionally, the organic laser systems 112A-112C may wirelessly communicate with the control unit 120. Further, an external interface 144 may be in communication with a user interface 146 via a communication conduit 148. Like the previous embodiment, the user interface 146 may communication with the external interface 144 wirelessly.

[0033] Figure 8 shows another embodiment of a tunable coherent light source. As shown, the tunable coherent light source 210 comprises at least one organic laser system 212 and at least one seed source 214. The seed source 214 receives power from a power supply 216 via a power conduit 218. In response thereto, the seed source 214 outputs a seed signal 226 to at least one modulator 224, which generates a modulated signal 23O.The modulated signal 230 may be conditioned by one or more optical elements 232 and directed to the organic laser system 212 positioned on a controllable stage 238. The organic laser system 212 may include one or more laser chips 242 configured to output an output signal 250 having a wide spectral range (white light), containing multiple wavelengths. The output signal 250 may be directed to an optical element 252 configured to subdivide the output signal 250 into various discreet wavelengths producing a spectral output 254. In one embodiment, the optical element 252 comprises one or more digital light processing chips. As such, the optical element 252 may be in communication with a control unit 220 via a conduit 228. Optionally, the optical element 252 may communicate with the control unit wirelessly. Those skilled in the art will appreciate that a variety of optical elements 252 may be used, including, without limitation, gratings and etalons.

[0034] The various devices disclosed herein may be manufactured in any variety of ways. In one embodiment, the tunable coherent laser system 10 may be constructed to form a modular device wherein individual components thereof may be easily replaced. For example, as shown in Figure 1 the controllable mount 38 may comprise a housing configured to detachably receive the organic laser system 12 therein. Similarly, the seed source 14 may be configured to be easily detached from the tunable coherent light source 10 thereby permitting easy servicing of the system. In an alternate embodiment, the tunable coherent light system 10 may be manufactured as an integrated system. For example, at least portion of the system, if not the entire system, may be manufacture as a single device, such as an assembly within housing or as an integrated chip device. [0035] The various embodiments disclosed herein are illustrative of the principles of the invention. Other modifications may be employed which are within the scope of the invention. Accordingly, the devices disclosed in the present application are not limited to that precisely as shown and described herein.

Claims

What is claimed is:

1. A tunable coherent light source, comprising:

at least one seed source configured to irradiate at least one seed signal;

at least one modulator configured to modulate the seed signal to a desired pulse width and repetition rate;

at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal;

at least one control unit in communication with at least one of the seed source, the modulator, and the organic laser system and configured to receive at least one input and generate a control signal; and

at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a desired wavelength.

2. The device of claim 1 wherein the seed source comprises at least one laser device.

3. The device of claim 1 wherein the seed signal has a wavelength of about 100nm to about 2000nm.

4. The device of claim 1 wherein the seed signal has a wavelength of about 300nm to about 400nm.

5. The device of claim 1 wherein the seed signal has a wavelength of about 340nm to about 370nm.

6. The device of claim 1 further comprising at least one sensor in communication with the control unit and configured to be irradiated by the tunable output and provide at least one data signal to the control unit in response thereto.

7. The device of claim 1 wherein the organic laser system is configured to output at least one optical signal having a wavelength from about 150nm to about 2000nm.

8. The device of claim 1 wherein the organic laser system is configured to output at least one optical signal having a wavelength from about 350nm to about 840nm.

9. The device of claim 1 wherein the modulator comprises an acousto-optic modulator.

10. The device of claim 1 wherein multiple organic laser systems are in communication with a seed source.

11. The device if claim 1 wherein multiple seed sources are in communication with an organic laser system.

12. The device of claim 1 further comprising at least one power supply in communication with at least one of the seed source, the modulator, the organic laser system, the control unit, and the controllable stage.

13. The device of claim 1 further comprising at least one optical element in optical communication with the tunable coherent light source.

14. The device of claim 13 where the optical element is selected from the group consisting of polarizers, wave plates, lenses, prisms, spatial filters, pinholes, optical crystals, mirrors, filters, power meters, beam profilers, gratings, and etalons.

15. The device of claim 1 wherein the organic laser system further comprises one or more organic laser chips comprised of a substrate forming a distributed Bragg grating having one or more layer of a spirofluorene derivative material applied thereto.

16. A tunable coherent light source, comprising:

at least one seed source configured to irradiate at least one seed signal;

at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, the organic laser system comprising one or more laser chips comprised of a substrate forming a distributed Bragg grating having at least one spirofluorene derivative applied thereto;

17. The device of claim 16 wherein the organic laser system is configured to output at least one optical signal having a wavelength from about 150nm to about 2000nm.

18. The device of claim 16 wherein multiple organic laser systems are in communication with a seed source.

19. The device if claim 19 wherein multiple seed sources are in communication with an organic laser system.

0. A tunable coherent light source, comprising:

at least one seed source configured to irradiate at least one seed signal;

at least one organic laser system configured to emit at least one tunable output at a desired wavelength when irradiated with the modulated seed signal, the organic laser system comprising one or more laser chips comprised of a substrate having at least one spirofluorene derivative applied thereto;

at least one controllable stage in communication with at least the control unit and configured to support the organic laser system, the controllable stage capable of controllably translating the organic laser system in response to the control signal to produce an output signal at a wavelength from about 350nm to about 840nm.