Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory... more Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory the authors have demonstrated a compact Tm{sup 3+}:YAG laser capable of generating greater than 50 W of cw 2 {micro}m laser output power. The design and operational characteristics of this laser will be discussed.
ABSTRACT Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for impl... more ABSTRACT Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B{sub 4}C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B{sub 4}C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 micrometers of B{sub 4}C. Thickness estimated from optical density agreed well with those measured by scanning electron microscopy (SEM). The B{sub 4}C microstructure was columnar but finer than for Be made at the same conditions. B{sub 4}C is a very strong material, with a fiber tensile strength capable of holding NIF fill pressures at room temperature, but it is also very brittle, and microscopic flaws or grain structure may limit the noncryogenic fill pressure. Argon (Ar) permeation rates were measured for a few capsules that had been further coated with 5 micrometers of plasma polymer. The B{sub 4}C coatings tended to crack under tensile load. Some shells filled more slowly than they leaked, suggesting that the cracks open and close under opposite pressure loading. As observed earlier for Ti coatings, 0.15-micrometer layers of B{sub 4}C had better gas retention properties than 2-micrometer layers, possibly because of fewer cracks. Permeation and fill strength issues for capsules with a full ablator thickness of B{sub 4}C are unresolved. 21 refs., 6 figs.
... S A. Payne, R J. Beach, C. Bibeau, C. A. Ebbers, MA Emanuel, E. C. Honea, W. F. Krupke, Lawre... more ... S A. Payne, R J. Beach, C. Bibeau, C. A. Ebbers, MA Emanuel, E. C. Honea, W. F. Krupke, Lawrence Livermore National Laboratory University of California Livermore, California 94550 C. D. Marshall, C. D. Orth, HT Powell, KI Schaffers, J. A. Skidmore, and S: B. Sutton ...
ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National L... more ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory we have demonstrated a compact Tm:YAG laser capable of generating greater than 50 W of cw 2 micrometer laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, are discussed. The 2 micrometer radiation produced by the 3F4 - 3H6 transition of Tm3+ has many practical applications because it is strongly absorbed by water and also because it is an 'eye-safe' wavelength. The strong absorption of 2 micrometer radiation by water makes this transition a very attractive candidate for performing laser surgical procedures as most tissue types are predominately composed of liquid water. The fact that 2 micrometer radiation is considered 'eye-safe' makes this transition attractive for laser range finding and remote sensing applications where other laser wavelengths could pose a safety hazard. At sufficiently high doping densities, Tm3+ exhibits a beneficial two-for-one quantum pump efficiency enabling well developed AlGaAs laser diode arrays to be used as efficient excitation sources. Many applications requiring 2 micrometer laser radiation such as remote sensing, laser radar, anti sensor, sensor spoofing, and OPO pumping have driven the development of diode pumped all solid state TM3+ laser systems because of their potential for efficiency, compactness, and ruggedness. Here we focus on Tm3+:YAG and the scalable diode end-pumping technology developed at LLNL which enables higher average power operation of diode pumped Tm3+ laser systems than has previously been possible. To date we have demonstrated cw operation of this laser to power levels of 51 W. The end-pumping technology used is the same as was previously used to demonstrate a 100 mJ Q-switched Nd:YLF laser. (Truncated.)
ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National L... more ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory we have demonstrated a compact Tm3+:YAG laser capable of generating greater than 50 W of cw 2 µm laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, will be discussed.
We present the energy, propagation, and thermal modeling for a diode-pumped solid-state laser cal... more We present the energy, propagation, and thermal modeling for a diode-pumped solid-state laser called Mercury being designed and built at LLNL using Yb:S-FAP [i.e., Yb3+-doped Sr5(PO4)3F crystals] for the gain medium. This laser is intended to produce 100 J pulses at 1 to 10 ns at 10 Hz with an electrical efficiency of approximately 10%. Our modeling indicates that the
A hollow lensing duct to condense (intensify) light using a combination of focusing using a spher... more A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the
Fiber Lasers X: Technology, Systems, and Applications, 2013
ABSTRACT Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for... more ABSTRACT Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for power scaling lasers to high power. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality and high efficiency. We present experimental results where we achieved > 3 kW at an M2 = 1.35 and > 39% E-O efficiency by combining 12 individual fiber lasers into a single high brightness beam.
ABSTRACT A scaleable diode end-pumping technology for high-average-power slab and rod lasers has ... more ABSTRACT A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.
Lasers, Sources, and Related Photonic Devices, 2012
ABSTRACT We describe our work on Spectral Beam Combining geometries and design implementations us... more ABSTRACT We describe our work on Spectral Beam Combining geometries and design implementations using multilayer dielectric gratings. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality.
Fiber Lasers X: Technology, Systems, and Applications, 2013
ABSTRACT We describe a pulsed blue (485 nm) laser source based on frequency quadrupling a pulsed ... more ABSTRACT We describe a pulsed blue (485 nm) laser source based on frequency quadrupling a pulsed Tm fiber laser. Up to 1.2 W at 485 nm was generated with an M2 of 1.3. At 10 kHz pulse repetition frequency, the output pulse at 485 nm was 65 ns FWHM resulting in an estimated peak power of 1.8 kW. We anticipate further improvements in power scaling with higher power Tm fiber lasers and improved conversion efficiency to the blue with optimized AR coatings and nonlinear optical crystals.
Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37088), 2000
... Radiative lifetimes and fractional thermal loadlng of Yb3A150,, (YbAG) and highly-doped Yb:Y,... more ... Radiative lifetimes and fractional thermal loadlng of Yb3A150,, (YbAG) and highly-doped Yb:Y,AI,O,, (Yb:YAG) F.1). Patel, BC Honea, J. Speth ... stress fracture is limited by thernial gradient, the ahility to keep the gain element thin while still having sulficient rare earth ion density IO ...
... Eric C. Honea, Raymond J. Beach, Steve B. Sutton, Joel A. Speth, Scott C. Mitchell, Jay A. Sk... more ... Eric C. Honea, Raymond J. Beach, Steve B. Sutton, Joel A. Speth, Scott C. Mitchell, Jay A. Skidmore, Mark A. Emanuel and ... be balanced with Tm concentration requirements for efficient cross-relaxatioy; The cross-relaxation process betwfen Tm ions, wherein an ion excited to ...
XI International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 1997
ABSTRACT The combination of our unique capabilities at LLNL in diode development, crystal growth,... more ABSTRACT The combination of our unique capabilities at LLNL in diode development, crystal growth, and system designs have allowed us to pursue a variety of research areas of interest to the commercial, medical, and defense industries. We have developed a flexible diode pumping technology which utilizes low cost silicon microchannel coolers to enable high average power diode operation and a shaped cylindrical microlens technology which allows the radiance conditioning of large two- dimensional laser diode arrays. The flexibility that this diode technology has brought to pump power generation in both average power and radiance have broadly expanded the number of ion-host combinations that can be efficiently excited and used in diode pumped solid state lasers. Some of our laser developments are briefly discussed.
Page 1. Four-Channel, High Power, Passively Phase Locked Fiber Array Thomas H. Loftus, Alison M. ... more Page 1. Four-Channel, High Power, Passively Phase Locked Fiber Array Thomas H. Loftus, Alison M. Thomas, Marc Norsen, John D. Minelly, Pat Jones, and Eric Honea Aculight Corporation, 22121 20th Avenue SE, Bothell, WA 98021 John.Minelly@aculight.com ...
Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory... more Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory the authors have demonstrated a compact Tm{sup 3+}:YAG laser capable of generating greater than 50 W of cw 2 {micro}m laser output power. The design and operational characteristics of this laser will be discussed.
ABSTRACT Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for impl... more ABSTRACT Boron carbide (B{sub 4}C) is examined as a potential fuel container and ablator for implosion capsules on the National Ignition Facility (NIF). A capsule of pure B{sub 4}C encasing a layer of solid DT implodes stably and ignites with anticipated NIF x-ray drives, producing 18 MJ of energy. Thin films of B{sub 4}C were found to be resistant to oxidation and modestly transmitting in the infrared (IR), possibly enabling IR fuel characterization and enhancement for thin permeation barriers but not for full-thickness capsules. Polystyrene mandrels 0.5 mm in diameter were successfully coated with 0.15-2.0 micrometers of B{sub 4}C. Thickness estimated from optical density agreed well with those measured by scanning electron microscopy (SEM). The B{sub 4}C microstructure was columnar but finer than for Be made at the same conditions. B{sub 4}C is a very strong material, with a fiber tensile strength capable of holding NIF fill pressures at room temperature, but it is also very brittle, and microscopic flaws or grain structure may limit the noncryogenic fill pressure. Argon (Ar) permeation rates were measured for a few capsules that had been further coated with 5 micrometers of plasma polymer. The B{sub 4}C coatings tended to crack under tensile load. Some shells filled more slowly than they leaked, suggesting that the cracks open and close under opposite pressure loading. As observed earlier for Ti coatings, 0.15-micrometer layers of B{sub 4}C had better gas retention properties than 2-micrometer layers, possibly because of fewer cracks. Permeation and fill strength issues for capsules with a full ablator thickness of B{sub 4}C are unresolved. 21 refs., 6 figs.
... S A. Payne, R J. Beach, C. Bibeau, C. A. Ebbers, MA Emanuel, E. C. Honea, W. F. Krupke, Lawre... more ... S A. Payne, R J. Beach, C. Bibeau, C. A. Ebbers, MA Emanuel, E. C. Honea, W. F. Krupke, Lawrence Livermore National Laboratory University of California Livermore, California 94550 C. D. Marshall, C. D. Orth, HT Powell, KI Schaffers, J. A. Skidmore, and S: B. Sutton ...
ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National L... more ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory we have demonstrated a compact Tm:YAG laser capable of generating greater than 50 W of cw 2 micrometer laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, are discussed. The 2 micrometer radiation produced by the 3F4 - 3H6 transition of Tm3+ has many practical applications because it is strongly absorbed by water and also because it is an 'eye-safe' wavelength. The strong absorption of 2 micrometer radiation by water makes this transition a very attractive candidate for performing laser surgical procedures as most tissue types are predominately composed of liquid water. The fact that 2 micrometer radiation is considered 'eye-safe' makes this transition attractive for laser range finding and remote sensing applications where other laser wavelengths could pose a safety hazard. At sufficiently high doping densities, Tm3+ exhibits a beneficial two-for-one quantum pump efficiency enabling well developed AlGaAs laser diode arrays to be used as efficient excitation sources. Many applications requiring 2 micrometer laser radiation such as remote sensing, laser radar, anti sensor, sensor spoofing, and OPO pumping have driven the development of diode pumped all solid state TM3+ laser systems because of their potential for efficiency, compactness, and ruggedness. Here we focus on Tm3+:YAG and the scalable diode end-pumping technology developed at LLNL which enables higher average power operation of diode pumped Tm3+ laser systems than has previously been possible. To date we have demonstrated cw operation of this laser to power levels of 51 W. The end-pumping technology used is the same as was previously used to demonstrate a 100 mJ Q-switched Nd:YLF laser. (Truncated.)
ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National L... more ABSTRACT Using a scalable diode end-pumping technology developed at Lawrence Livermore National Laboratory we have demonstrated a compact Tm3+:YAG laser capable of generating greater than 50 W of cw 2 µm laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, will be discussed.
We present the energy, propagation, and thermal modeling for a diode-pumped solid-state laser cal... more We present the energy, propagation, and thermal modeling for a diode-pumped solid-state laser called Mercury being designed and built at LLNL using Yb:S-FAP [i.e., Yb3+-doped Sr5(PO4)3F crystals] for the gain medium. This laser is intended to produce 100 J pulses at 1 to 10 ns at 10 Hz with an electrical efficiency of approximately 10%. Our modeling indicates that the
A hollow lensing duct to condense (intensify) light using a combination of focusing using a spher... more A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the
Fiber Lasers X: Technology, Systems, and Applications, 2013
ABSTRACT Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for... more ABSTRACT Spectral Beam Combining (SBC) of fiber lasers provides a simple, robust architecture for power scaling lasers to high power. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality and high efficiency. We present experimental results where we achieved > 3 kW at an M2 = 1.35 and > 39% E-O efficiency by combining 12 individual fiber lasers into a single high brightness beam.
ABSTRACT A scaleable diode end-pumping technology for high-average-power slab and rod lasers has ... more ABSTRACT A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.
Lasers, Sources, and Related Photonic Devices, 2012
ABSTRACT We describe our work on Spectral Beam Combining geometries and design implementations us... more ABSTRACT We describe our work on Spectral Beam Combining geometries and design implementations using multilayer dielectric gratings. With appropriate designs, power scaling beyond the single fiber limit can be achieved while maintaining near diffraction limited beam quality.
Fiber Lasers X: Technology, Systems, and Applications, 2013
ABSTRACT We describe a pulsed blue (485 nm) laser source based on frequency quadrupling a pulsed ... more ABSTRACT We describe a pulsed blue (485 nm) laser source based on frequency quadrupling a pulsed Tm fiber laser. Up to 1.2 W at 485 nm was generated with an M2 of 1.3. At 10 kHz pulse repetition frequency, the output pulse at 485 nm was 65 ns FWHM resulting in an estimated peak power of 1.8 kW. We anticipate further improvements in power scaling with higher power Tm fiber lasers and improved conversion efficiency to the blue with optimized AR coatings and nonlinear optical crystals.
Conference on Lasers and Electro-Optics (CLEO 2000). Technical Digest. Postconference Edition. TOPS Vol.39 (IEEE Cat. No.00CH37088), 2000
... Radiative lifetimes and fractional thermal loadlng of Yb3A150,, (YbAG) and highly-doped Yb:Y,... more ... Radiative lifetimes and fractional thermal loadlng of Yb3A150,, (YbAG) and highly-doped Yb:Y,AI,O,, (Yb:YAG) F.1). Patel, BC Honea, J. Speth ... stress fracture is limited by thernial gradient, the ahility to keep the gain element thin while still having sulficient rare earth ion density IO ...
... Eric C. Honea, Raymond J. Beach, Steve B. Sutton, Joel A. Speth, Scott C. Mitchell, Jay A. Sk... more ... Eric C. Honea, Raymond J. Beach, Steve B. Sutton, Joel A. Speth, Scott C. Mitchell, Jay A. Skidmore, Mark A. Emanuel and ... be balanced with Tm concentration requirements for efficient cross-relaxatioy; The cross-relaxation process betwfen Tm ions, wherein an ion excited to ...
XI International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 1997
ABSTRACT The combination of our unique capabilities at LLNL in diode development, crystal growth,... more ABSTRACT The combination of our unique capabilities at LLNL in diode development, crystal growth, and system designs have allowed us to pursue a variety of research areas of interest to the commercial, medical, and defense industries. We have developed a flexible diode pumping technology which utilizes low cost silicon microchannel coolers to enable high average power diode operation and a shaped cylindrical microlens technology which allows the radiance conditioning of large two- dimensional laser diode arrays. The flexibility that this diode technology has brought to pump power generation in both average power and radiance have broadly expanded the number of ion-host combinations that can be efficiently excited and used in diode pumped solid state lasers. Some of our laser developments are briefly discussed.
Page 1. Four-Channel, High Power, Passively Phase Locked Fiber Array Thomas H. Loftus, Alison M. ... more Page 1. Four-Channel, High Power, Passively Phase Locked Fiber Array Thomas H. Loftus, Alison M. Thomas, Marc Norsen, John D. Minelly, Pat Jones, and Eric Honea Aculight Corporation, 22121 20th Avenue SE, Bothell, WA 98021 John.Minelly@aculight.com ...
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