US20070098024A1 - High power, end pumped laser with off-peak pumping - Google Patents
High power, end pumped laser with off-peak pumping Download PDFInfo
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- US20070098024A1 US20070098024A1 US11/261,010 US26101005A US2007098024A1 US 20070098024 A1 US20070098024 A1 US 20070098024A1 US 26101005 A US26101005 A US 26101005A US 2007098024 A1 US2007098024 A1 US 2007098024A1
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- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/0941—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light of a laser diode
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- H01S3/08—Construction or shape of optical resonators or components thereof
- H01S3/081—Construction or shape of optical resonators or components thereof comprising three or more reflectors
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- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094084—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators
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- H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
- H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
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- H01S3/16—Solid materials
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- H01S3/1603—Solid materials characterised by an active (lasing) ion rare earth
- H01S3/1611—Solid materials characterised by an active (lasing) ion rare earth neodymium
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- H01S3/1643—YAG
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- H01S5/4031—Edge-emitting structures
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- H01S5/405—Two-dimensional arrays
Definitions
- the present invention relates to laser systems, and more particularly to high-power, end-pumped laser systems with solid-state gain media.
- High power laser output is desired over a broad range of wavelengths and disciplines throughout the scientific, industrial and medical fields. Many systems have been developed to generate high-power. However, systems generating output power levels in excess of several hundred Watts become very complex. Also, some systems generate such high-powers only at the expense of beam quality.
- the amount of energy used for pumping the gain medium is increased.
- many solid-state media exhibit thermal lensing or other problems causing aberrations in output beam.
- the pump energy can be applied from the side of the gain medium, known as a side-pumping, or from the end of the gain medium, known as the end-pumping, in most systems.
- Other systems create complex optics for filling a gain medium with pump energy. Side-pumping is relatively inefficient; so that the conversion of pump energy into laser output is low at relatively high pump energies. End-pumping is more efficient.
- Butterworth, U.S. Pat. No. 6,898,231 B2 describes a laser based on a gain medium comprising neodymium Nd doped yttrium orthovanadate (“vanadate”), in which the pump energy is set at a wavelength which is absorbed with an efficiency substantially less than that of the peak absorption wavelengths, thereby allowing more of the pump energy to penetrate a greater volume of the gain medium before being absorbed and distributing the generated heat.
- vanadate crystal was on the order of five millimeters long, and the doping concentration was relatively high at about 0.5 atomic percent.
- Hardman et al. “Energy-Transfer up Conversion and Thermal Lensing and High-Power End-Pumped Nd:YLF Laser Crystals,” IEEE JOURNAL OF QUANTUM ELECTRONICS, Volume 35, No. 4, April 1999, describes a longitudinally pumped laser with the pump wavelength detuned in order to increase the absorption length within the YLF host to about three millimeters.
- Pollnau et al. “Up Conversion-Induced Heat Generation and a Thermal Lensing in Nd:YLF and Nd:YAG,” PHYSICAL REVIEW B, Volume 58, No. 24, 15 Dec. 1998, p.
- a high quality laser easily producing over 100 Watts output power is provided using a laser configuration, described herein, based on a solid-state gain medium, a source of pump energy which is detuned from the maximum absorption wavelength for the gain medium, and optics arranged to deliver the pump energy through an end of the gain medium to propagate along the length of the gain medium.
- the optics delivering the pump energy, the length of the gain medium and the doping concentration in the gain medium are set in described configurations so that that 80 percent or more, and preferably more than 90 percent, of the pump energy is absorbed within the gain medium.
- these parameters are designed so that the absorption length, at which 1/e of the pump energy is absorbed, is on the order of 10's of millimeters, greater than 50 millimeters in some embodiments, and preferably at least one third, greater than one half in some embodiments, of the length of the gain medium.
- Embodiments of the laser system described herein include a pump energy source that supplies 500 Watts or more of energy at a wavelength which has an absorption efficiency that is about 20 percent or less of a maximum absorption efficiency for the gain medium and active element.
- a laser system is described with a gain medium comprising a rod shaped YAG host with a Nd doping concentration between about 0.05 and 0.5 atomic percent, where the length of the doped YAG host is substantially greater than 50 millimeters, such as 100 millimeters, with a diameter on the order of 10 millimeters or less, and with a source of pump energy providing greater than 500 Watts in a wavelength between 799 and 803 nanometers.
- Intra-cavity doubled outputs of more that 100 Watts are produced in described configurations. More than 200 Watts output power at 1.064 ⁇ m is available in these configurations.
- the configurations described herein are scalable to produce lower powers, of for example 50 Watts, up to 1000 Watts or more, output in the frequency converted wavelengths, and correspondingly high power primary wavelength outputs.
- the output wavelength can be configured to fall in a range from about 200 to about 1100 nm in embodiments described herein.
- the gain medium comprises a long rod of the crystalline host such as YAG, with an undoped end-cap on the first end through which the pump radiation enters the crystal, and optionally with an undoped end-cap on the second end as well.
- the pump energy is delivered using optics in an embodiment described herein, which focus the pump energy at a focal point near one end of the gain medium, for propagation along the length of the gain medium.
- Optical elements are included that are arranged to provide a resonant cavity, which is mode-matched with the spot size of the pump energy at the focal point. The result of this configuration is a high quality output beam, with M 2 less than 30, suitable for coupling into fiber optic delivery systems and focusing on relatively small targets.
- the laser system is configured to provide output beams that are a frequency converted beam, such as a first, second or third harmonic of the primary wavelength within the laser system.
- a component for frequency conversion is included within the resonant cavity.
- an embodiment of the system includes a Q-switch within the resonant cavity, for producing high energy, high frequency pulses of output laser light.
- the laser configuration described herein is suitable for generation of more than 100 Watts of output at 532 nanometers using an Nd:YAG gain medium and diode laser pumping source.
- the configuration is stable, easily manufactured and low-cost.
- an end-pumped high-power laser which produces a low M 2 beam with stable output power.
- Output powers greater than 100 and even greater than 1000 Watts can be produced using solid-state hosts and diode laser pump sources.
- the laser configuration supports efficient intra-cavity frequency conversion.
- FIG. 1 is a simplified diagram of a diode pumped, solid-state laser system producing over 100 Watts frequency converted output power.
- FIG. 2 illustrates one end of a gain medium in a system such as described with reference to FIG. 1 .
- FIG. 3 is a schematic illustration of the distribution of pump energy at one end of the gain medium for a system such as described with reference to FIG. 1 .
- FIG. 4 illustrates in intensity profile on at least one dimension of the pump energy delivered to one end of the gain medium for a system such as described with reference to FIG. 1 .
- FIG. 5 is a graph of absorption efficiency versus wavelength for pump energy sources in an Nd:YAG gain medium.
- FIG. 6 is a simplified diagram of an alternative diode pumped, solid-state laser system for producing high output powers.
- FIGS. 1-6 A detailed description of embodiments of the present invention is provided with reference to the FIGS. 1-6 .
- FIG. 1 illustrates a high-power laser system comprising a gain medium 10 that includes a doped crystalline host, having a first end 11 and a second end 12 .
- the gain medium 10 in a representative embodiment comprises Nd:YAG having a length of about 100 millimeters and a diameter of about 4.5 millimeters.
- the gain medium 10 is water cooled in exemplary embodiments, along the sides of the host.
- Undoped endcap 13 about 10 millimeters long in this example, is bonded on the first end 11 of the gain medium 10
- undoped endcap 14 also about 10 millimeters long in this example, is bonded on the second end 12 of the gain medium 10 .
- the undoped endcap 13 can be diffusion bonded but preferably grown on at least the first end 11 .
- another undoped endcap 14 can be diffusion bonded but preferably grown on the second end 12 .
- the output end of the undoped endcap 14 is coated so that it is reflective at the pump energy wavelength, while transmitting at the resonant mode. In this manner, the pump energy that is unabsorbed at the second end 12 is redirected back to the rod to be absorbed.
- rod-end lens effects play a very significant role in the stability of the resonator.
- a source of pump energy in the illustrated embodiment comprises a diode array 15 .
- a representative embodiment employs a seven bar stack of diode lasers, with each bar producing 100 Watts for 700 Watts total pump energy, centered on 801 nanometers. The wavelength of the bars changes plus or minus 1.5 nanometers in normal operating conditions providing pump energy within a range of about 799 to about 803 nanometers.
- FIG. 5 shows the absorption efficiency versus pump energy wavelength over practical range of wavelengths, for Nd:YAG.
- a maximum in the range occurs at about 808 nanometers.
- the pump energy range of 799 to 803 lies substantially off the peak at 808, at a level that is less that 20 percent of the maximum absorption.
- the absorption is less than about 10% of the maximum absorption at the peak near 808 nanometers.
- Other pump energy ranges are suitable as well, including wavelengths near 825 nanometers or beyond the illustrated range.
- One specific advantage of pumping at wavelength with absorption efficiencies that are substantially off peak is a tolerance to wavelength shifts. When pumping at 801 nanometers in the Nd:YAG in the described embodiment, wavelength shifts of plus or minus 1.5 nanometers have essentially no effect on the laser output.
- Pump energy is delivered through optics, including a fast axis collimation lens 16 , a polarization multiplexer which acts as a beam interleaver, brightness doubler 17 , and a set of lenses 18 arranged as a telescope to focus the pump energy near the first end 11 of the gain medium 10 .
- the pump energy is delivered at the output of the fast access collimation lenses 16 on a path 20 to the beam interleaver, brightness doubler 17 .
- the pump energy is concentrated to one half its width at the output of the beam interleaver, brightness doubler 17 on path 21 and is delivered through the lenses 18 on path 22 to a focal point at or near the first end 11 of the gain medium 10 .
- the fast axis collimation lens 16 can be deliberately defocused slightly to facilitate homogenization of the pump beam at the focal point in the gain medium 10 .
- the beam interleaver, brightness doubler 17 reduces the width of the pump energy output by one half, facilitating focusing of the pump energy into a relatively small diameter rod shaped gain medium 10 , with a longer working distance.
- the lenses 18 can be varied to adjust the spot size at an image plane in the gain medium 10 over a range of operating parameters as suits a particular implementation. For example, the spot size at the focal point can be varied over range about 10 percent to about 90 percent of the diameter of the rod shaped gain medium 10 .
- the pump energy passes through a beam splitter 19 that is used to turn the resonating energy to the optics defining resonant cavity.
- the system includes optical elements including concave mirror 25 , that is highly reflective at the resonating energy of 1064 nanometers, beam splitter 19 , which is reflective at 1064 nanometers and transmissive at the wavelength of the pump energy source around 801 nanometers, concave mirror 26 that is highly reflective at 1064 nanometers and transmissive at an output wavelength of 532 nanometers, concave mirror 27 that is highly reflective at both 1064 and 532 nanometers, and concave mirror 28 which is highly reflective at both 1064 and 532 nanometers.
- the optical elements 25 , 19 , 26 , 27 , 28 define a resonant path 32 which is essentially Z-shaped, with a tail between then beam splitter 19 and the highly reflective concave mirror 25 .
- Q-switch 29 is placed in the resonant cavity between the mirrors 26 and 27 .
- a nonlinear crystal 30 such as LBO, is placed between the mirrors 27 and 28 .
- the Z-shaped resonant cavity can be configured as discussed in U.S. Pat. No. 5,025,446 by Kuizenga, imaging the resonant mode at one end of the gain medium 10 at the nonlinear crystal 30 .
- the configuration described is stable and highly efficient for frequency conversion.
- the configuration shown in FIG. 1 produces a frequency converted output (wavelength 532 nanometers in illustrated embodiment) of greater than 100 Watts on line 31 .
- FIGS. 2 and 3 illustrate features of the pump spot size at the focal point.
- FIG. 2 shows the gain medium 10 , and the undoped endcap 13 on the first end 11 of the gain medium 10 .
- the pump energy is focused on path 22 to the focal point near the first end 11 . This establishes an aperture near the first end for the resonant mode in the cavity.
- the gain is inversely proportional to the area and divergence of the pump beam at the focal point near the first end 11 of the gain medium 10 at the doped/undoped interface of the rod. The smaller the spot size, the high the gain for a given rod.
- FIG. 3 illustrates the distribution light from the pump energy source at the first end 11 on the rod, which results from imaging the output of the laser diode source on the first end 11 of the rod.
- FIG. 3 there are seven rows of diode laser outputs, such as row 50 .
- the result is a substantially uniform intensity profile, as illustrated in FIG. 4 along the horizontal dimension in the FIG. 4 , which lies on an axis that is parallel to the row 50 of laser diode spots.
- the rows are separated by a small distance in the vertical dimension in an embodiment where the fast axis collimation lenses 16 are focused.
- the distribution of energy can be made more uniform in the second, vertical dimension.
- the system is designed therefore to homogenize and flatten the pump profile to reduce the thermal lensing.
- the spot size at the image plane affects transverse modes of the laser.
- the transverse modes of the laser are controlled by the pump spot size and distribution of energy within about the first 30 percent of the rod length in which a most of the pump energy is absorbed.
- the mode quality improves.
- the optical elements 25 , 19 , 26 , 27 , 28 defining the resonant cavity are configured to mode match with the aperture defined by the pump energy spot size at the focal point.
- the doping concentration in the gain medium 10 is chosen based on the mode quality and output power required.
- the doping level is relatively low to allow distribution of the thermal load along the optical axis of the gain medium 10 (e.g., 1/e absorption length of more than 50 millimeters in a rod less than 10 millimeters in diameter), thereby reducing the thermal stresses induced at the input to the gain medium.
- the doping concentration is about 0.27 atomic percent for the rod shown in FIG. 1 , that is about 100 millimeters long between the first end 11 and the second end 12 , and pumped substantially off-peak at about 801 nanometers where the absorption efficiency is less than 10 percent of the maximum absorption efficiency at the peak near 808 nanometers for Nd:YAG.
- the 1/e absorption length for this embodiment is about 66 millimeters, more than half the length of the 100 millimeters rod.
- Ranges of doping concentrations for embodiments of the invention comprising an Nd:YAG rod can fall within about 0.05 and about 0.5 atomic percent, and more preferably in a range between about 0.2 and 0.4 atomic percent for readily and consistently manufacturable commercial applications.
- the pump energy wavelength, doping concentration and the length of the rod are adapted in a preferred embodiment, so that the absorption length is over one third the rod length, and more than 90 percent of the pump energy is absorbed within two passes along the length of the rod, as the unabsorbed pump energy which reaches the second end 12 of the rod is reflected back towards the first end 11 .
- the amount of unabsorbed pump energy that reaches the first end 11 is very low, and has insubstantial effects on the characteristics of the pump energy at the focal point.
- output powers greater than 100 Watts of frequency converted output at 532 nanometers are readily generated with an Nd:YAG rod about 100 millimeters long and about 4.5 millimeters in diameter with reasonably high quality beam.
- the technology is scalable to configurations supporting pump energy in the kilowatt range for hundreds of Watts of output power in the primary and harmonic wavelengths for the laser.
- Beam quality can be characterized by the parameter M 2 .
- M 2 the higher M 2 , the lower the beam quality, and the more difficult it is to focus of the beam on a small spot and to couple the beam into small numerical aperture delivery devices such as fiber optics.
- M 2 of less than 30 is readily achieved using the technology described herein, allowing coupling into fiber optics on the order 100 microns and up in diameter, which provides a beam with low divergence suitable for many high-power applications of laser light, including medical applications.
- the technology described herein is adaptable to other configurations of the resonant cavity, with or without frequency conversion and with or without Q-switching, and adaptable to other gain media and pump energy sources within the parameters described herein.
- FIG. 6 illustrates one alternative laser system configuration, in which pump energy is provided at both ends of the gain medium, for higher output powers.
- a gain medium 100 having a length between a first end 101 and a second end 102 , on the order 50 to 100 millimeters or longer, is provided.
- Undoped endcaps 103 , 104 are grown on the first end 101 and second end 102 respectively.
- a first source of pump energy 105 directs more than 100 Watts of pump energy through a beam splitter 107 to an image plane near the first end 101 at a wavelength which is detuned from the maximum absorption wavelength for the gain medium.
- a second source of pump energy 106 directs more than 100 Watts of pump energy through a beam splitter 108 to an image plane near the second end 102 , at a wavelength which is detuned from the maximum absorption wavelength.
- Optical components 109 and 110 are arranged to provide resonant cavity for the primary wavelength.
- the combination of parameters including the length for the gain medium, the doping concentration, the pump energy profiles at the focal points on the ends of the gain medium, and the pump energy wavelengths substantially detuned from the maximum absorption wavelengths, are established for absorption lengths of at least one-third of the rod length, so that high output powers and high quality beams are produced.
- the resonator components represented by block 10 are adapted to a particular application of the laser system, and may comprise of mirrors, polarizers, Q-switches, non-linear crystals, apertures, filters, etalons, half wave plates, and other devices.
- Embodiments of the laser system may deploy one or more diode stacks or other pump energy sources, may include one or more gain media, and may include a variety of resonant cavity configurations.
- Laser systems employing the technology described herein can be implemented that operate in a continuous wave CW mode, a Q-switched mode and mode-locked modes, depending on the preferred output characteristics.
- An end-pumped, high-power laser which produces an output with low M 2 and stable output power.
- the doping level of the gain medium is adjusted, the pump wavelength is detuned off major pump bands, and the length of the gain medium is a selected to allow very high-power pumping while maintaining low thermal stress and thermal lensing.
- the gain aperture for the system can be determined by the spot size of the pump energy imaged on an end of the gain medium.
- the laser system can be very efficiently intra-cavity frequency converted to second, third and higher harmonic frequencies.
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Abstract
Description
- 1. Field of the Invention
- The present invention relates to laser systems, and more particularly to high-power, end-pumped laser systems with solid-state gain media.
- 2. Description of Related Art
- High power laser output is desired over a broad range of wavelengths and disciplines throughout the scientific, industrial and medical fields. Many systems have been developed to generate high-power. However, systems generating output power levels in excess of several hundred Watts become very complex. Also, some systems generate such high-powers only at the expense of beam quality.
- In solid-state systems, in order to generate a higher output powers, the amount of energy used for pumping the gain medium is increased. However, many solid-state media exhibit thermal lensing or other problems causing aberrations in output beam. The pump energy can be applied from the side of the gain medium, known as a side-pumping, or from the end of the gain medium, known as the end-pumping, in most systems. Other systems create complex optics for filling a gain medium with pump energy. Side-pumping is relatively inefficient; so that the conversion of pump energy into laser output is low at relatively high pump energies. End-pumping is more efficient. However, an upper limit is quickly reached for end-pumped gain media, where rapid absorption of pump energy in a small volume within the first few millimeters of the gain media causes thermal fracture. Thermal damage to solid-state gain media can be controlled by sophisticated cooling techniques, such as is employed in so-called disk lasers. Also, thermal lensing which occurs in some solid-state gain media can be managed by including undoped endcaps. An undoped end-cap bonded on a gain medium prevents deformation at the surface of the gain medium due to the high absorption and heat generation on the surface.
- Techniques have been investigated that increase the volume of the gain medium in which the pump energy is absorbed, and in which the resulting heat is generated, to prevent thermal damage and manage thermal lensing. One way to distribute heat generation within the gain medium which has been investigated includes reducing the doping concentration of the active material. At lower doping concentrations, less energy is absorbed within a given volume. See, Honea et al., “Analysis of intracavity-doubled diode-pumped Q-switched Nd:YAG laser producing more than 100 W of power at 0.532 μm,” OPTICS LETTERS, Vol. 23, No. 15, Aug. 1, 1998, pages 1203-1205.
- Butterworth, U.S. Pat. No. 6,898,231 B2 describes a laser based on a gain medium comprising neodymium Nd doped yttrium orthovanadate (“vanadate”), in which the pump energy is set at a wavelength which is absorbed with an efficiency substantially less than that of the peak absorption wavelengths, thereby allowing more of the pump energy to penetrate a greater volume of the gain medium before being absorbed and distributing the generated heat. In the Butterworth patent for example, the vanadate crystal was on the order of five millimeters long, and the doping concentration was relatively high at about 0.5 atomic percent. Hardman et al., “Energy-Transfer up Conversion and Thermal Lensing and High-Power End-Pumped Nd:YLF Laser Crystals,” IEEE JOURNAL OF QUANTUM ELECTRONICS, Volume 35, No. 4, April 1999, describes a longitudinally pumped laser with the pump wavelength detuned in order to increase the absorption length within the YLF host to about three millimeters. Pollnau et al., “Up Conversion-Induced Heat Generation and a Thermal Lensing in Nd:YLF and Nd:YAG,” PHYSICAL REVIEW B, Volume 58, No. 24, 15 Dec. 1998, p. 16076-16092, also describes off-peak pumping for a YLF host, while suggesting that off-peak pumping is not necessary for a YAG host because “rod fracture is not a problem.” (See; Pollnau et al., page 16077). See also, Wu et al., U.S. Pat. No. 6,347,101 B1; and Chang et al., U.S. Pat. No. 6,504,858 B2. The Wu et al., Chang et al., Butterworth, Hardman et al. and Pollnau et al. publications describe systems that use relatively low pump powers from diode lasers, on the order of 20 or 30 Watts. The resulting output powers of the lasers are therefore relatively small, and not suitable for many applications.
- High power outputs have been achieved for Tm:YAG diode pumped lasers producing 2 μm wavelength outputs, and applying off-peak pumping with pump powers over 300 Watts. Tm doped media demonstrate two-for-one cross relaxation, improving pumping efficiency, so long as the pump intensity is high enough. Honea et al. report up to 115
W 2 μm wavelength outputs in this configuration, with off peak pumping. Honea et al., “15-W Tm:YAG Diode-Pumped Solid-State Laser,” IEEE JOURNAL OF QUANTUM ELECTRONICS, Vol. 33, No. 9, September 1997, pages 1592-1600. - It is desirable to provide a laser system generating high-quality, high-power outputs in a manufacturable configuration.
- A high quality laser easily producing over 100 Watts output power is provided using a laser configuration, described herein, based on a solid-state gain medium, a source of pump energy which is detuned from the maximum absorption wavelength for the gain medium, and optics arranged to deliver the pump energy through an end of the gain medium to propagate along the length of the gain medium.
- The optics delivering the pump energy, the length of the gain medium and the doping concentration in the gain medium are set in described configurations so that that 80 percent or more, and preferably more than 90 percent, of the pump energy is absorbed within the gain medium. In configurations described, these parameters are designed so that the absorption length, at which 1/e of the pump energy is absorbed, is on the order of 10's of millimeters, greater than 50 millimeters in some embodiments, and preferably at least one third, greater than one half in some embodiments, of the length of the gain medium.
- Embodiments of the laser system described herein include a pump energy source that supplies 500 Watts or more of energy at a wavelength which has an absorption efficiency that is about 20 percent or less of a maximum absorption efficiency for the gain medium and active element. For example, a laser system is described with a gain medium comprising a rod shaped YAG host with a Nd doping concentration between about 0.05 and 0.5 atomic percent, where the length of the doped YAG host is substantially greater than 50 millimeters, such as 100 millimeters, with a diameter on the order of 10 millimeters or less, and with a source of pump energy providing greater than 500 Watts in a wavelength between 799 and 803 nanometers. Intra-cavity doubled outputs of more that 100 Watts are produced in described configurations. More than 200 Watts output power at 1.064 μm is available in these configurations. The configurations described herein are scalable to produce lower powers, of for example 50 Watts, up to 1000 Watts or more, output in the frequency converted wavelengths, and correspondingly high power primary wavelength outputs. The output wavelength can be configured to fall in a range from about 200 to about 1100 nm in embodiments described herein.
- In embodiments of the laser system described herein, the gain medium comprises a long rod of the crystalline host such as YAG, with an undoped end-cap on the first end through which the pump radiation enters the crystal, and optionally with an undoped end-cap on the second end as well.
- The pump energy is delivered using optics in an embodiment described herein, which focus the pump energy at a focal point near one end of the gain medium, for propagation along the length of the gain medium. Optical elements are included that are arranged to provide a resonant cavity, which is mode-matched with the spot size of the pump energy at the focal point. The result of this configuration is a high quality output beam, with M2 less than 30, suitable for coupling into fiber optic delivery systems and focusing on relatively small targets.
- An embodiment is described in which the laser system is configured to provide output beams that are a frequency converted beam, such as a first, second or third harmonic of the primary wavelength within the laser system. In such an embodiment, a component for frequency conversion is included within the resonant cavity. Also, an embodiment of the system includes a Q-switch within the resonant cavity, for producing high energy, high frequency pulses of output laser light.
- The laser configuration described herein is suitable for generation of more than 100 Watts of output at 532 nanometers using an Nd:YAG gain medium and diode laser pumping source. The configuration is stable, easily manufactured and low-cost.
- In summary, an end-pumped high-power laser is described which produces a low M2 beam with stable output power. Output powers greater than 100 and even greater than 1000 Watts can be produced using solid-state hosts and diode laser pump sources. The laser configuration supports efficient intra-cavity frequency conversion.
- Other aspects and advantages of the present invention can be seen on review of the drawings, the detailed description and the claims, which follow.
-
FIG. 1 is a simplified diagram of a diode pumped, solid-state laser system producing over 100 Watts frequency converted output power. -
FIG. 2 illustrates one end of a gain medium in a system such as described with reference toFIG. 1 . -
FIG. 3 is a schematic illustration of the distribution of pump energy at one end of the gain medium for a system such as described with reference toFIG. 1 . -
FIG. 4 illustrates in intensity profile on at least one dimension of the pump energy delivered to one end of the gain medium for a system such as described with reference toFIG. 1 . -
FIG. 5 is a graph of absorption efficiency versus wavelength for pump energy sources in an Nd:YAG gain medium. -
FIG. 6 is a simplified diagram of an alternative diode pumped, solid-state laser system for producing high output powers. - A detailed description of embodiments of the present invention is provided with reference to the
FIGS. 1-6 . -
FIG. 1 illustrates a high-power laser system comprising again medium 10 that includes a doped crystalline host, having afirst end 11 and asecond end 12. Thegain medium 10 in a representative embodiment comprises Nd:YAG having a length of about 100 millimeters and a diameter of about 4.5 millimeters. Thegain medium 10 is water cooled in exemplary embodiments, along the sides of the host.Undoped endcap 13 about 10 millimeters long in this example, is bonded on thefirst end 11 of thegain medium 10, andundoped endcap 14 also about 10 millimeters long in this example, is bonded on thesecond end 12 of thegain medium 10. - In the high-power end-pumped configuration shown, the
undoped endcap 13 can be diffusion bonded but preferably grown on at least thefirst end 11. In embodiments where significant pump energy reaches the second end of thehost 10, anotherundoped endcap 14 can be diffusion bonded but preferably grown on thesecond end 12. The output end of theundoped endcap 14 is coated so that it is reflective at the pump energy wavelength, while transmitting at the resonant mode. In this manner, the pump energy that is unabsorbed at thesecond end 12 is redirected back to the rod to be absorbed. At the very high pump powers possible using the configuration described herein, rod-end lens effects play a very significant role in the stability of the resonator. Strong absorption of the pump energy at the surface of the gain medium can cause significant distortion to the end face and at high-power levels rod fracture. Rod distortion leads to strong spherical aberration of the beam which severely reduces the quality of the beam. By bonding undoped endcaps onto the doped rod ends, the distortion is avoided, because the absorption now takes place in the bulk and not at a surface. Also, the fracture limit is higher and end effects are substantially eliminated. - A source of pump energy in the illustrated embodiment comprises a
diode array 15. A representative embodiment employs a seven bar stack of diode lasers, with each bar producing 100 Watts for 700 Watts total pump energy, centered on 801 nanometers. The wavelength of the bars changes plus or minus 1.5 nanometers in normal operating conditions providing pump energy within a range of about 799 to about 803 nanometers. -
FIG. 5 shows the absorption efficiency versus pump energy wavelength over practical range of wavelengths, for Nd:YAG. As shown, a maximum in the range occurs at about 808 nanometers. The pump energy range of 799 to 803 lies substantially off the peak at 808, at a level that is less that 20 percent of the maximum absorption. For 801, plus or minus 1.5 nanometers, the absorption is less than about 10% of the maximum absorption at the peak near 808 nanometers. Other pump energy ranges are suitable as well, including wavelengths near 825 nanometers or beyond the illustrated range. One specific advantage of pumping at wavelength with absorption efficiencies that are substantially off peak is a tolerance to wavelength shifts. When pumping at 801 nanometers in the Nd:YAG in the described embodiment, wavelength shifts of plus or minus 1.5 nanometers have essentially no effect on the laser output. - Pump energy is delivered through optics, including a fast
axis collimation lens 16, a polarization multiplexer which acts as a beam interleaver,brightness doubler 17, and a set oflenses 18 arranged as a telescope to focus the pump energy near thefirst end 11 of thegain medium 10. The pump energy is delivered at the output of the fastaccess collimation lenses 16 on apath 20 to the beam interleaver,brightness doubler 17. The pump energy is concentrated to one half its width at the output of the beam interleaver,brightness doubler 17 onpath 21 and is delivered through thelenses 18 onpath 22 to a focal point at or near thefirst end 11 of thegain medium 10. - In embodiments of the invention, the fast
axis collimation lens 16 can be deliberately defocused slightly to facilitate homogenization of the pump beam at the focal point in thegain medium 10. The beam interleaver,brightness doubler 17 reduces the width of the pump energy output by one half, facilitating focusing of the pump energy into a relatively small diameter rod shapedgain medium 10, with a longer working distance. Thelenses 18 can be varied to adjust the spot size at an image plane in thegain medium 10 over a range of operating parameters as suits a particular implementation. For example, the spot size at the focal point can be varied over range about 10 percent to about 90 percent of the diameter of the rod shapedgain medium 10. - The pump energy passes through a
beam splitter 19 that is used to turn the resonating energy to the optics defining resonant cavity. The system includes optical elements includingconcave mirror 25, that is highly reflective at the resonating energy of 1064 nanometers,beam splitter 19, which is reflective at 1064 nanometers and transmissive at the wavelength of the pump energy source around 801 nanometers,concave mirror 26 that is highly reflective at 1064 nanometers and transmissive at an output wavelength of 532 nanometers,concave mirror 27 that is highly reflective at both 1064 and 532 nanometers, andconcave mirror 28 which is highly reflective at both 1064 and 532 nanometers. Theoptical elements resonant path 32 which is essentially Z-shaped, with a tail between thenbeam splitter 19 and the highly reflectiveconcave mirror 25. - In the illustrated embodiment, Q-
switch 29 is placed in the resonant cavity between themirrors nonlinear crystal 30, such as LBO, is placed between themirrors gain medium 10 at thenonlinear crystal 30. The configuration described is stable and highly efficient for frequency conversion. The configuration shown inFIG. 1 produces a frequency converted output (wavelength 532 nanometers in illustrated embodiment) of greater than 100 Watts online 31. - The pump spot size at the image plane near the
first end 11 of thegain medium 10 affects in the mode quality of the laser system, controls the gain, and the strength of the thermal lensing.FIGS. 2 and 3 illustrate features of the pump spot size at the focal point.FIG. 2 shows thegain medium 10, and theundoped endcap 13 on thefirst end 11 of thegain medium 10. The pump energy is focused onpath 22 to the focal point near thefirst end 11. This establishes an aperture near the first end for the resonant mode in the cavity. The gain is inversely proportional to the area and divergence of the pump beam at the focal point near thefirst end 11 of thegain medium 10 at the doped/undoped interface of the rod. The smaller the spot size, the high the gain for a given rod. The thermal lens is also inversely proportional to the pump spot size at the image plane. As the pump spot gets smaller, the thermal lens increases. Also, the distribution of light across the pump spot has a strong effect on the thermal lens.FIG. 3 illustrates the distribution light from the pump energy source at thefirst end 11 on the rod, which results from imaging the output of the laser diode source on thefirst end 11 of the rod. As illustrated inFIG. 3 , there are seven rows of diode laser outputs, such asrow 50. The result is a substantially uniform intensity profile, as illustrated inFIG. 4 along the horizontal dimension in theFIG. 4 , which lies on an axis that is parallel to therow 50 of laser diode spots. The rows are separated by a small distance in the vertical dimension in an embodiment where the fastaxis collimation lenses 16 are focused. By slightly defocusing the fastaxis collimation lenses 16, the distribution of energy can be made more uniform in the second, vertical dimension. The system is designed therefore to homogenize and flatten the pump profile to reduce the thermal lensing. - Also, the spot size at the image plane affects transverse modes of the laser. The transverse modes of the laser are controlled by the pump spot size and distribution of energy within about the first 30 percent of the rod length in which a most of the pump energy is absorbed. As the spot size at the image plane is reduced, the mode quality improves. The
optical elements - The doping concentration in the
gain medium 10 is chosen based on the mode quality and output power required. The doping level is relatively low to allow distribution of the thermal load along the optical axis of the gain medium 10 (e.g., 1/e absorption length of more than 50 millimeters in a rod less than 10 millimeters in diameter), thereby reducing the thermal stresses induced at the input to the gain medium. In an embodiment described, the doping concentration is about 0.27 atomic percent for the rod shown inFIG. 1 , that is about 100 millimeters long between thefirst end 11 and thesecond end 12, and pumped substantially off-peak at about 801 nanometers where the absorption efficiency is less than 10 percent of the maximum absorption efficiency at the peak near 808 nanometers for Nd:YAG. The 1/e absorption length for this embodiment is about 66 millimeters, more than half the length of the 100 millimeters rod. - Ranges of doping concentrations for embodiments of the invention comprising an Nd:YAG rod can fall within about 0.05 and about 0.5 atomic percent, and more preferably in a range between about 0.2 and 0.4 atomic percent for readily and consistently manufacturable commercial applications. The pump energy wavelength, doping concentration and the length of the rod are adapted in a preferred embodiment, so that the absorption length is over one third the rod length, and more than 90 percent of the pump energy is absorbed within two passes along the length of the rod, as the unabsorbed pump energy which reaches the
second end 12 of the rod is reflected back towards thefirst end 11. The amount of unabsorbed pump energy that reaches thefirst end 11 is very low, and has insubstantial effects on the characteristics of the pump energy at the focal point. - By establishing a suitable combination of parameters including the length for the gain medium, the doping concentration, the pump energy profile at the image plane, and the pump energy wavelength, output powers greater than 100 Watts of frequency converted output at 532 nanometers are readily generated with an Nd:YAG rod about 100 millimeters long and about 4.5 millimeters in diameter with reasonably high quality beam. The technology is scalable to configurations supporting pump energy in the kilowatt range for hundreds of Watts of output power in the primary and harmonic wavelengths for the laser.
- Beam quality can be characterized by the parameter M2. The higher M2, the lower the beam quality, and the more difficult it is to focus of the beam on a small spot and to couple the beam into small numerical aperture delivery devices such as fiber optics. M2 of less than 30 is readily achieved using the technology described herein, allowing coupling into fiber optics on the
order 100 microns and up in diameter, which provides a beam with low divergence suitable for many high-power applications of laser light, including medical applications. - The technology described herein is adaptable to other configurations of the resonant cavity, with or without frequency conversion and with or without Q-switching, and adaptable to other gain media and pump energy sources within the parameters described herein.
-
FIG. 6 illustrates one alternative laser system configuration, in which pump energy is provided at both ends of the gain medium, for higher output powers. In the illustrated system, again medium 100 having a length between afirst end 101 and asecond end 102, on theorder 50 to 100 millimeters or longer, is provided.Undoped endcaps first end 101 andsecond end 102 respectively. A first source ofpump energy 105 directs more than 100 Watts of pump energy through abeam splitter 107 to an image plane near thefirst end 101 at a wavelength which is detuned from the maximum absorption wavelength for the gain medium. A second source ofpump energy 106 directs more than 100 Watts of pump energy through abeam splitter 108 to an image plane near thesecond end 102, at a wavelength which is detuned from the maximum absorption wavelength.Optical components block 10 are adapted to a particular application of the laser system, and may comprise of mirrors, polarizers, Q-switches, non-linear crystals, apertures, filters, etalons, half wave plates, and other devices. - Embodiments of the laser system may deploy one or more diode stacks or other pump energy sources, may include one or more gain media, and may include a variety of resonant cavity configurations. Laser systems employing the technology described herein can be implemented that operate in a continuous wave CW mode, a Q-switched mode and mode-locked modes, depending on the preferred output characteristics.
- An end-pumped, high-power laser is described which produces an output with low M2 and stable output power. The doping level of the gain medium is adjusted, the pump wavelength is detuned off major pump bands, and the length of the gain medium is a selected to allow very high-power pumping while maintaining low thermal stress and thermal lensing. The gain aperture for the system can be determined by the spot size of the pump energy imaged on an end of the gain medium. The laser system can be very efficiently intra-cavity frequency converted to second, third and higher harmonic frequencies.
- While the present invention is disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than in a limiting sense. It is contemplated that modifications and combinations will readily occur to those skilled in the art, which modifications and combinations will be within the spirit of the invention and the scope of the following claims.
Claims (50)
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JP2008538164A JP4970459B2 (en) | 2005-10-28 | 2006-10-26 | High power, end-pumped laser with off-peak pumping |
PCT/US2006/060259 WO2007051138A2 (en) | 2005-10-28 | 2006-10-26 | High power, end pumped laser with off-peak pumping |
ES06846164.9T ES2546109T3 (en) | 2005-10-28 | 2006-10-26 | Laser pumping end, high power, with pumping out of peak |
AU2006305812A AU2006305812B2 (en) | 2005-10-28 | 2006-10-26 | High power, end pumped laser with off-peak pumping |
EP06846164.9A EP1946413B1 (en) | 2005-10-28 | 2006-10-26 | High power, end pumped laser with off-peak pumping |
CA2627418A CA2627418C (en) | 2005-10-28 | 2006-10-26 | High power, end pumped laser with off-peak pumping |
US12/034,756 US7995638B2 (en) | 2005-10-28 | 2008-02-21 | High power, end pumped laser with off-peak pumping |
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Citations (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4907235A (en) * | 1988-04-01 | 1990-03-06 | Laserscope | Intra-cavity beam relay for optical harmonic generation |
US4974230A (en) * | 1988-08-23 | 1990-11-27 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array |
US5205466A (en) * | 1992-07-15 | 1993-04-27 | Chieh-Chang Tzeng | Manufacturing method of austenitic stainless steel self-tapping and self-drilling screw |
US5530709A (en) * | 1994-09-06 | 1996-06-25 | Sdl, Inc. | Double-clad upconversion fiber laser |
US5638397A (en) * | 1994-02-04 | 1997-06-10 | Spectra-Physics Lasers, Inc. | Confocal-to-concentric diode pumped laser |
US5689522A (en) * | 1995-10-02 | 1997-11-18 | The Regents Of The University Of California | High efficiency 2 micrometer laser utilizing wing-pumped Tm3+ and a laser diode array end-pumping architecture |
US5844149A (en) * | 1996-09-19 | 1998-12-01 | Nkk Corporation | Method for analyzing solid specimen and apparatus therefor |
US5859868A (en) * | 1996-01-22 | 1999-01-12 | Nec Corporation | Solid-state laser device which is pumped by light output from laser diode |
US5907570A (en) * | 1997-10-22 | 1999-05-25 | Spectra-Physics, Inc. | Diode pumped laser using gain mediums with strong thermal focussing |
US6026101A (en) * | 1996-06-09 | 2000-02-15 | Ricoh Company, Ltd. | Solid-state laser apparatus |
US6069907A (en) * | 1996-09-10 | 2000-05-30 | Olive Tree Technology, Inc. | Laser diode pumped solid state laser and method using same |
US6185236B1 (en) * | 1999-02-02 | 2001-02-06 | University Of Central Florida | Self frequency double nd-doped: YCOB LASER |
US6246706B1 (en) * | 1999-05-27 | 2001-06-12 | Spectra Physics Lasers, Inc. | Laser writing method and apparatus |
US6347101B1 (en) * | 1998-04-16 | 2002-02-12 | 3D Systems, Inc. | Laser with absorption optimized pumping of a gain medium |
US6366596B1 (en) * | 2000-01-21 | 2002-04-02 | Photonics Industries International, Inc. | High power laser |
US6407535B1 (en) * | 2000-09-08 | 2002-06-18 | The Regents Of The University Of California | System for beaming power from earth to a high altitude platform |
US6421573B1 (en) * | 1999-05-27 | 2002-07-16 | Spectra Physics Lasers, Inc. | Quasi-continuous wave lithography apparatus and method |
US6483858B1 (en) * | 1999-11-23 | 2002-11-19 | Southeastern University Research Assn. | Injection mode-locking Ti-sapphire laser system |
US6504858B2 (en) * | 1998-11-24 | 2003-01-07 | Spectra Physics Lasers, Inc. | Lasers with low doped gain medium |
US6570902B2 (en) * | 1998-11-12 | 2003-05-27 | Raytheon Company | Laser with gain medium configured to provide an integrated optical pump cavity |
US6661568B2 (en) * | 2000-08-29 | 2003-12-09 | Jenoptik Laser, Optik Systeme Gmbh | Diode-pumped laser amplifier |
US6671305B2 (en) * | 1996-11-29 | 2003-12-30 | Corporation For Laser Optics Research | Solid state laser |
US6898231B2 (en) * | 2002-11-21 | 2005-05-24 | Coherent, Inc. | Off-peak optical pumping of yttrium orthovanadate |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5025446A (en) | 1988-04-01 | 1991-06-18 | Laserscope | Intra-cavity beam relay for optical harmonic generation |
JPH04137775A (en) | 1990-09-28 | 1992-05-12 | Nec Corp | Semiconductor laser excitation solid state laser |
ITTO20020173A1 (en) * | 2002-02-28 | 2003-08-28 | Bright Solutions Soluzioni Las | PUMPING METHOD OF A LASER CAVITY AND RELATIVE LASER SYSTEM. |
US6896231B1 (en) * | 2003-01-23 | 2005-05-24 | Thomas E. Sullivan, Sr. | Articulated drink holder assembly for disabled persons |
DE60304564T3 (en) * | 2003-05-30 | 2011-05-05 | Lumera Laser Gmbh | Improved optical pumping of materials with polarization-dependent absorption |
JP4137775B2 (en) | 2003-12-02 | 2008-08-20 | Tdk株式会社 | Suspension retention pallet |
-
2005
- 2005-10-28 US US11/261,010 patent/US20070098024A1/en not_active Abandoned
-
2006
- 2006-10-26 EP EP06846164.9A patent/EP1946413B1/en active Active
- 2006-10-26 EP EP15168519.5A patent/EP2950403B1/en active Active
- 2006-10-26 ES ES06846164.9T patent/ES2546109T3/en active Active
- 2006-10-26 CA CA2627418A patent/CA2627418C/en not_active Expired - Fee Related
- 2006-10-26 AU AU2006305812A patent/AU2006305812B2/en not_active Ceased
- 2006-10-26 WO PCT/US2006/060259 patent/WO2007051138A2/en active Application Filing
- 2006-10-26 JP JP2008538164A patent/JP4970459B2/en not_active Expired - Fee Related
-
2008
- 2008-02-21 US US12/034,756 patent/US7995638B2/en active Active
Patent Citations (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4907235A (en) * | 1988-04-01 | 1990-03-06 | Laserscope | Intra-cavity beam relay for optical harmonic generation |
US4974230A (en) * | 1988-08-23 | 1990-11-27 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Tm,Ho:YLF laser end-pumped by a semiconductor diode laser array |
US5205466A (en) * | 1992-07-15 | 1993-04-27 | Chieh-Chang Tzeng | Manufacturing method of austenitic stainless steel self-tapping and self-drilling screw |
US5638397A (en) * | 1994-02-04 | 1997-06-10 | Spectra-Physics Lasers, Inc. | Confocal-to-concentric diode pumped laser |
US5530709A (en) * | 1994-09-06 | 1996-06-25 | Sdl, Inc. | Double-clad upconversion fiber laser |
US5689522A (en) * | 1995-10-02 | 1997-11-18 | The Regents Of The University Of California | High efficiency 2 micrometer laser utilizing wing-pumped Tm3+ and a laser diode array end-pumping architecture |
US5859868A (en) * | 1996-01-22 | 1999-01-12 | Nec Corporation | Solid-state laser device which is pumped by light output from laser diode |
US6026101A (en) * | 1996-06-09 | 2000-02-15 | Ricoh Company, Ltd. | Solid-state laser apparatus |
US6069907A (en) * | 1996-09-10 | 2000-05-30 | Olive Tree Technology, Inc. | Laser diode pumped solid state laser and method using same |
US5844149A (en) * | 1996-09-19 | 1998-12-01 | Nkk Corporation | Method for analyzing solid specimen and apparatus therefor |
US6671305B2 (en) * | 1996-11-29 | 2003-12-30 | Corporation For Laser Optics Research | Solid state laser |
US5907570A (en) * | 1997-10-22 | 1999-05-25 | Spectra-Physics, Inc. | Diode pumped laser using gain mediums with strong thermal focussing |
US6347101B1 (en) * | 1998-04-16 | 2002-02-12 | 3D Systems, Inc. | Laser with absorption optimized pumping of a gain medium |
US6570902B2 (en) * | 1998-11-12 | 2003-05-27 | Raytheon Company | Laser with gain medium configured to provide an integrated optical pump cavity |
US6504858B2 (en) * | 1998-11-24 | 2003-01-07 | Spectra Physics Lasers, Inc. | Lasers with low doped gain medium |
US6185236B1 (en) * | 1999-02-02 | 2001-02-06 | University Of Central Florida | Self frequency double nd-doped: YCOB LASER |
US6246706B1 (en) * | 1999-05-27 | 2001-06-12 | Spectra Physics Lasers, Inc. | Laser writing method and apparatus |
US6421573B1 (en) * | 1999-05-27 | 2002-07-16 | Spectra Physics Lasers, Inc. | Quasi-continuous wave lithography apparatus and method |
US6483858B1 (en) * | 1999-11-23 | 2002-11-19 | Southeastern University Research Assn. | Injection mode-locking Ti-sapphire laser system |
US6366596B1 (en) * | 2000-01-21 | 2002-04-02 | Photonics Industries International, Inc. | High power laser |
US6661568B2 (en) * | 2000-08-29 | 2003-12-09 | Jenoptik Laser, Optik Systeme Gmbh | Diode-pumped laser amplifier |
US6407535B1 (en) * | 2000-09-08 | 2002-06-18 | The Regents Of The University Of California | System for beaming power from earth to a high altitude platform |
US6898231B2 (en) * | 2002-11-21 | 2005-05-24 | Coherent, Inc. | Off-peak optical pumping of yttrium orthovanadate |
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US9711928B2 (en) | 2012-06-22 | 2017-07-18 | Clemson University Research Foundation | Single crystals with internal doping with laser ions prepared by a hydrothermal method |
US9469915B2 (en) | 2012-06-22 | 2016-10-18 | Clemson University Research Foundation | Hydrothermal growth of heterogeneous single crystals exhibiting amplified spontaneous emission suppression |
US10156025B2 (en) | 2015-05-04 | 2018-12-18 | University Of South Carolina | Monolithic heterogeneous single crystals with multiple regimes for solid state laser applications |
US20210167570A1 (en) * | 2018-05-22 | 2021-06-03 | Jerusalem College Technology | Q-switched laser system |
US11791602B2 (en) * | 2018-05-22 | 2023-10-17 | Jerusalem College Technology | Q-switched laser system |
US20220209491A1 (en) * | 2020-12-24 | 2022-06-30 | Viettel Group | Structure and configuration of the passively q-switched diode end-pumped solid-state laser |
US12009628B2 (en) * | 2020-12-24 | 2024-06-11 | Viettel Group | Structure and configuration of the passively Q-switched diode end-pumped solid-state laser |
Also Published As
Publication number | Publication date |
---|---|
EP2950403A3 (en) | 2016-01-06 |
WO2007051138A2 (en) | 2007-05-03 |
CA2627418A1 (en) | 2007-05-03 |
WO2007051138A3 (en) | 2008-07-10 |
EP1946413A2 (en) | 2008-07-23 |
EP2950403B1 (en) | 2018-11-21 |
AU2006305812A1 (en) | 2007-05-03 |
EP1946413A4 (en) | 2011-09-14 |
US20080144690A1 (en) | 2008-06-19 |
ES2546109T3 (en) | 2015-09-18 |
EP1946413B1 (en) | 2015-06-17 |
AU2006305812B2 (en) | 2010-08-12 |
JP4970459B2 (en) | 2012-07-04 |
EP2950403A2 (en) | 2015-12-02 |
CA2627418C (en) | 2011-09-20 |
US7995638B2 (en) | 2011-08-09 |
JP2009514236A (en) | 2009-04-02 |
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