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Evaluation of the {sup 4}I{sub 11/2} terminal level lifetime for several neodymium-doped laser crystals and glasses

Description: All models of lasing action require knowledge of the physical parameters involved, of which many can be measured or estimated. The value of the terminal level lifetime is an important parameter in modeling many high power laser systems since the terminal level lifetime can have a substantial impact on the extraction efficiency of the system. However, the values of the terminal level lifetimes for a number of important laser materials such as ND:YAG and ND:YLF are not well known. The terminal level lifetime, a measure of the time it takes for the population to drain out of the terminal (lower) lasing level, has values that can range from picoseconds to microseconds depending on the host medium, thus making it difficult to construct one definitive experiment for all materials. Until recently, many of the direct measurements of the terminal level lifetime employed complex energy extraction or gain recovery methods coupled with a numerical model which often resulted in large uncertainties in the measured lifetimes. In this report we demonstrate a novel and more accurate approach which employs a pump-probe technique to measure the terminal level lifetime of 16 neodymium-doped materials. An alternative yet indirect method, which is based on the ``Energy Gap Law,`` is to measure the nonradiative lifetime of another transition which has the same energy gap as the transition of the terminal level lifetime. Employing this simpler approach, we measured the lifetime for 30 neodymium-doped materials. We show for the first time a direct comparison between the two methods and determine that the indirect method can be used to infer the terminal level lifetime within a factor of two for most neodymium-doped glasses and crystals.
Date: April 25, 1995
Creator: Bibeau, C.
Partner: UNT Libraries Government Documents Department

April 25, 2003, FY2003 Progress Summary and FY2002 Program Plan, Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers,and Complementary Technologies, for Applications in Energy and Defense

Description: The High Average Power Laser Program (HAPL) is a multi-institutional, synergistic effort to develop inertial fusion energy (IFE). This program is building a physics and technology base to complement the laser-fusion science being pursued by DOE Defense programs in support of Stockpile Stewardship. The primary institutions responsible for overseeing and coordinating the research activities are the Naval Research Laboratory (NRL) and Lawrence Livermore National Laboratory (LLNL). The current LLNL proposal is a companion document to the one submitted by NRL, for which the driver development element is focused on the krypton fluoride excimer laser option. The NRL and LLNL proposals also jointly pursue complementary activities with the associated rep-rated laser technologies relating to target fabrication, target injection, final optics, fusion chamber, target physics, materials and power plant economics. This proposal requests continued funding in FY03 to support LLNL in its program to build a 1 kW, 100 J, diode-pumped, crystalline laser, as well as research into high gain fusion target design, fusion chamber issues, and survivability of the final optic element. These technologies are crucial to the feasibility of inertial fusion energy power plants and also have relevance in rep-rated stewardship experiments. The HAPL Program pursues technologies needed for laser-driven IFE. System level considerations indicate that a rep-rated laser technology will be needed, operating at 5-10 Hz. Since a total energy of {approx}2 MJ will ultimately be required to achieve suitable target gain with direct drive targets, the architecture must be scaleable. The Mercury Laser is intended to offer such an architecture. Mercury is a solid state laser that incorporates diodes, crystals and gas cooling technologies.
Date: October 25, 2005
Creator: Meier, W & Bibeau, C
Partner: UNT Libraries Government Documents Department

Next-generation laser for Inertial Confinement Fusion

Description: We report on the progress in developing and building the Mercury laser system as the first in a series of a new generation of diode- pumped solid-state Inertial Confinement Fusion (ICF) lasers at Lawrence Livermore National Laboratory (LLNL). Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced high energy density (HED) physics applications. Primary performance goals include 10% efficiencies at 10 Hz and a 1-10 ns pulse with 1 omega energies of 100 J and with 2 omega/3 omega frequency conversion.
Date: September 29, 1997
Creator: Marshall, C.D.; Deach, R.J. & Bibeau, C.
Partner: UNT Libraries Government Documents Department

Next generation laser for Inertial Confinement Fusion

Description: We are in the process of developing and building the ``Mercury`` laser system as the first in a series of a new generation of diode-pumped solid-state Inertial Confinement Fusion (ICF) lasers at LLNL. Mercury will be the first integrated demonstration of a scalable laser architecture compatible with advanced high energy density (HED) physics applications. Primary performance goals include 10% efficiencies at 10 Hz and a 1-10 ns pulse with 1{omega} energies of 100 J and with 2{omega}/3{omega} frequency conversion.
Date: July 18, 1997
Creator: Marshall, C.D.; Beach, J. & Bibeau, C.
Partner: UNT Libraries Government Documents Department

CW and Q-switched performance of a diode end-pumped Yb:YAG laser. Revision 1

Description: Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 226 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.
Date: February 19, 1997
Creator: Bibeau, C.; Beach, R.; Ebbers, C.; Emanuel, M. & Skidmore, J.
Partner: UNT Libraries Government Documents Department

Performance of a diode-end-pumped Yb:YAG laser

Description: Using an end-pumped technology developed at LLNL we have demonstrated a Yb:YAG laser capable of delivering up to 434 W of CW power and 280 W of Q-switched power. In addition, we have frequency doubled the output to 515 nm using a dual crystal scheme to produce 76 W at 10 kHz in a 30 ns pulse length.
Date: May 5, 1997
Creator: Bibeau, C.; Beach, R.; Ebbers, C. & Emanuel, M.
Partner: UNT Libraries Government Documents Department

Recent advances and challenges for diode-pumped solid-state lasers as an inertial fusion energy driver candidate

Description: We discuss how solid-state laser technology can serve in the interests of fusion energy beyond the goals of the National Ignition Facility (NIF), which is now being constructed to ignite a deuterium-tritium target to fusion conditions in the laboratory for the first time. We think that advanced solid-state laser technology can offer the repetition-rate and efficiency needed to drive a fusion power plant, in contrast to the single-shot character of NIF. As discuss below, we propose that a gas-cooled, diode-pumped Yb:S-FAP laser can provide a new paradigm for fusion laser technology leading into the next century.
Date: December 23, 1997
Creator: Payne, S.A.; Beach, R.J. & Bibeau, C.
Partner: UNT Libraries Government Documents Department

Rapport Juin-Juillet 1999

Description: This report describes the optical system which allows the delivery, in an efficient and homogeneous way, of the pump light from the diode arrays of the Mercury laser system described in the two previous reports. I will, first, describe the present pumping line ; the description of the Advanced Pumping Design (APD) being given in the second part of this report.
Date: August 18, 1999
Creator: Bibeau, C & Chanteloupe, J C
Partner: UNT Libraries Government Documents Department

Pulse shaping on the Nova laser system

Description: Inertial confinement fusion requires temporally shaped pulses to achieve high gain efficiency. Recently, we demonstrated the ability to produce complex temporal pulse shapes at high power at 0.35 microns on the Nova laser system. 2 refs., 2 figs.
Date: February 6, 1989
Creator: Lawson, J.K.; Speck, D.R.; Bibeau, C. & Weiland, T.L.
Partner: UNT Libraries Government Documents Department

Optical tuning a dichroic multilayer for a high fluence laser application

Description: We report on the design and successful fabrication of a dichroic multilayer stack using a procedure that allowed shifting from high reflectance to high transmittance within 89 rim and surviving high laser fluences. A design approach based on quarter-wave thick layers allowed the multilayer stack to be optically tuned in the last layers of the stack. In our case, this necessitated removing the samples from the coating chamber for a transmittance scan prior to depositing the last layers. This procedure is not commonly practiced due to thermal stress-induced failures in an oxide multilayer. However, D.J. Smith and co-workers reported that reactive e-beam evaporated hafnia from a Hf source produced laser-resistant coatings that had less coating stress compared to coatings evaporated from a HfO{sub 2} source. Tuned dichroic coatings were made that had high transmittance at 941 rim and high reflectance at 1030 nm. The coating was exposed for 5 minutes to a 100 kW/cm{sup 2} 1064 nm (180-ns pulsewidth, 10.7 kHz) laser beam and survived without microscopic damage. The same coating survived a 140 kW/cm{sup 2} of laser intensity without catastrophic damage before optical tuning were performed.
Date: October 11, 1995
Creator: R. Chow, Loomis, G.E.; Bibeau, C.; Molau, N.E.; Kanz, V.K. & Beach, R.J.
Partner: UNT Libraries Government Documents Department

Yttrium Calcium Oxyborate for high average power frequency doubling and OPCPA

Description: Significant progress has been achieved recently in the growth of Yttrium Calcium Oxyborate (YCOB) crystals. Boules have been grown capable of producing large aperture nonlinear crystal plates suitable for high average power frequency conversion or optical parametric chirped pulse amplification (OPCPA). With a large aperture (5.5 cm x 8.5 cm) YCOB crystal we have demonstrated a record 227 W of 523.5nm light (22.7 J/pulse, 10 Hz, 14 ns). We have also demonstrated the applicability of YCOB for 1053 nm OPCPA.
Date: June 20, 2006
Creator: Liao, Z M; Jovanovic, I; Ebbers, C A; Bayramian, A; Schaffers, K; Caird, J et al.
Partner: UNT Libraries Government Documents Department

Laser damage initiation and growth of antireflection coated S-FAP crystal surfaces prepared by pitch lap and magnetorheological finishing

Description: Antireflection (AR) coatings typically damage at the interface between the substrate and coating. Therefore the substrate finishing technology can have an impact on the laser resistance of the coating. For this study, AR coatings were deposited on Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals that received a final polish by both conventional pitch lap finishing as well as magnetorheological finishing (MRF). SEM images of the damage morphology reveals laser damage originates at scratches and at substrate coating interfacial absorbing defects. Previous damage stability tests on multilayer mirror coatings and bare surfaces revealed damage growth can occur at fluences below the initiation fluence. The results from this study suggest the opposite trend for AR coatings. Investigation of unstable HR and uncoated surface damage morphologies reveals significant radial cracking that is not apparent with AR damage due to AR delamination from the coated surface with few apparent cracks at the damage boundary. Damage stability tests show that coated Yb:S-FAP crystals can operate at 1057 nm at fluences around 20 J/cm{sup 2} at 10 ns; almost twice the initiation damage threshold.
Date: October 31, 2005
Creator: Stolz, C J; Menapace, J A; Schaffers, K I; Bibeau, C; Thomas, M D & Griffin, A J
Partner: UNT Libraries Government Documents Department

Performance of a Nova beamline with high damage threshold glass

Description: We report on measurements made on a Nova beamline whose output amplifier stages contain new high damage threshold, platinum particle-free laser glass. We project future operating limits for the Nova ten beam amplifier system. 4 refs.
Date: November 19, 1987
Creator: Bibeau, C.; Ehrlich, R.B.; Lawson, J.K.; Laumann, C.W.; Pennington, D.M.; Weiland, T.L. et al.
Partner: UNT Libraries Government Documents Department

Modeling of large aperture third harmonic frequency conversion of high power Nd:glass laser systems

Description: To provide high-energy, high-power beams at short wavelengths for inertial-confinement-fusion experiments, we routinely convert the 1.053-{mu}m output of the Nova, Nd:phosphate-glass, laser system to its third-harmonic wavelength. We describe performance and conversion efficiency modeling of the 3 {times} 3 arrays potassium-dihydrogen-phosphate crystal plates used for type II/type II phase-matched harmonic conversion of Nova 0.74-m diameter beams, and an alternate type I/type II phase-matching configuration that improves the third-harmonic conversion efficiency. These arrays provide energy conversion of up to 65% and intensity conversion to 70%. 19 refs., 11 figs.
Date: March 13, 1991
Creator: Henesian, M.A.; Wegner, P.J.; Speck, D.R.; Bibeau, C.; Ehrlich, R.B.; Laumann, C.W. et al.
Partner: UNT Libraries Government Documents Department

The National Ignition Facility: The World's Largest Laser

Description: The National Ignition Facility (NIF) is a 192-beam laser facility presently under construction at LLNL. When completed, NIF will be a 1.8-MJ, 500-TW ultraviolet laser system. Its missions are to obtain fusion ignition and to perform high energy density experiments in support of the U.S. nuclear weapons stockpile. Four of the NIF beams have been commissioned to demonstrate laser performance including target and beam alignment. During this time, NIF demonstrated on a single-beam basis that it will meet its performance goals and demonstrated its precision and flexibility for pulse shaping, pointing, timing and beam conditioning. It also performed four important experiments for Inertial Confinement Fusion and High Energy Density Science. Presently, the project is installing production hardware to complete the project in 2009 with the goal to begin ignition experiments in 2010. An integrated plan has been developed including the NIF operations, user equipment such as diagnostics and cryogenic target capability, and experiments and calculations to meet this goal.
Date: September 29, 2005
Creator: Moses, E I; Bibeau, C; Bonanno, R E; Haynam, C A; MacGowan, B J; Kauffman, R L et al.
Partner: UNT Libraries Government Documents Department

High-average-power diode-pumped Yb: YAG lasers

Description: 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.
Date: October 1, 1999
Creator: Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C et al.
Partner: UNT Libraries Government Documents Department