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Heat capacity disk laser

Description: In this paper we describe the concept, and the basic scaling relation ships of solid state heat capacity lasers. Intermediate between single shot and average power systems, the heat capacity concept scales solid state lasers to MW levels of burst power.
Date: June 4, 1998
Creator: Albrecht, G. F.
Partner: UNT Libraries Government Documents Department

Dynamics of Wet Oxidation of High-AL-Content III-V Materials

Description: Oxidation of layers of high-Al-content III-V materials by water vapor has become the enabling process for high-efficiency vertical cavity surface emitting lasers (VCSELS) and has potential applications for reducing substrate current leakage in GaAs-on-insulator (GOI) MESFETS. Because of the established importance of wet oxidation in optoelectronic devices and its potential applications in electronic devices, it has become increasingly important to understand the mechanism of wet oxidation and how it might be expected to affect both the fabrication and subsequent operation of devices that have been made using this technique. The mechanism of wet oxidation and the consequence of this mechanism for heterostructure design and ultimate device operation are discussed here.
Date: January 27, 1999
Creator: Ashby, C.I.H.
Partner: UNT Libraries Government Documents Department

Prospects for inertial fusion energy based on a diode-pumped solid-state laser (DPSSL) driver: Overview and development path

Description: It is now known with certainty that the type of fusion known as inertial fusion will work with sufficient energy input, so inertial fusion is really beyond the ``scientific breakeven`` point in many respects. The most important question that remains for inertial fusion energy (IFE) is whether this type of fusion can operate with sufficiently low input energy to make it economically feasible for energy production. The constraint for low input energy demands operation near the inertial fusion ignition threshold, and such operation creates enormous challenges to discover a target design that will produce sufficient energy gain. There are also multiple issues relating to the scientific feasibility of using a laboratory-type ``driver`` to energize a target, such as those concerning bandwidth and beam smoothing for ``direct drive,`` and extension of hohlraum plasma physics to the IFE scale for ``indirect drive.`` One driver that appears as though it will be able to meet the IFE requirements, assuming modest development and sufficient target gain, is a diode-pumped solid-state laser (DPSSL). We give an overview of this type of laser system, and explain what development remains for the economic production of electricity using this type of driver for IFE.
Date: March 1, 1997
Creator: Orth, C.D.
Partner: UNT Libraries Government Documents Department

High power 2 {mu}m diode-pumped Tm:YAG laser

Description: Using a scaleable diode end-pumping technology developed at LLNL, we have demonstrated a compact Tm:YAG laser capable of generating more than 50 W of cw 2 {mu}m laser output power. The design and operational characteristics of this laser, which was built originally for use in assessing laser surgical techniques, are discussed.
Date: January 1, 1996
Creator: Beach, R.J.; Sutton, S.B.; Honea, E.C.; Skidmore, J.A. & Emanuel, M.A.
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

Aluminum-Free Semiconductors and Packaging

Description: The use of laser diodes instead of flashlamps to pump solid state lasers generally results in lighter weight, more compact systems with improved efficiency and reliability. These traits are important to a wide variety of applications in military, industrial and other areas. Common solid state laser systems such as yttrium aluminum garnet doped with neodymium or ytterbium (Nd:YAG and Yb:YAG, respectively) require pump light in the 800 to 1000 nm range, and such laser diodes have typically been fabricated in the AlGaAs material system on a GaAs substrate. Unfortunately, the presence of aluminum in or near the light-generating regions of these devices appears to limit their high-power performance, so for improved performance attention has turned to the aluminum-free (''Al-free'') material system of InGaAsP on a GaAs substrate. Laser diodes in this system offer the wavelength coverage similar to the AlGaAs/GaAs material system, and early results suggest that they may offer improved high-power performance. However, such Al-free diodes are more challenging to manufacture than AlGaAs-based devices. The goal of this LDRD project has been to evaluate Al-free diode technology in comparison with conventional AlGaAs-based structures for use in diode-pumped solid state lasers. This has been done by testing commercially available devices, surveying the literature, developing in-house capability in order to explore new device designs, and by engaging a leading university research group in the field.
Date: February 3, 2000
Creator: Emanuel, M.A.
Partner: UNT Libraries Government Documents Department

Survey of Laser Markets Relevant to Inertial Fusion Energy Drivers, information for National Research Council

Description: Development of a new technology for commercial application can be significantly accelerated by leveraging related technologies used in other markets. Synergies across multiple application domains attract research and development (R and D) talent - widening the innovation pipeline - and increases the market demand in common components and subsystems to provide performance improvements and cost reductions. For these reasons, driver development plans for inertial fusion energy (IFE) should consider the non-fusion technology base that can be lveraged for application to IFE. At this time, two laser driver technologies are being proposed for IFE: solid-state lasers (SSLs) and KrF gas (excimer) lasers. This document provides a brief survey of organizations actively engaged in these technologies. This is intended to facilitate comparison of the opportunities for leveraging the larger technical community for IFE laser driver development. They have included tables that summarize the commercial organizations selling solid-state and KrF lasers, and a brief summary of organizations actively engaged in R and D on these technologies.
Date: February 24, 2011
Creator: Bayramian, A. J.; Deri, R. J. & Erlandson, A. C.
Partner: UNT Libraries Government Documents Department

Gratings for Increasing Solid-State Laser Gain and Efficiency

Description: We introduce new concepts for increasing the efficiency of solid state lasers by using gratings deposited on laser slabs or disks. The gratings improve efficiency in two ways: (1) by coupling out of the slab deleterious amplified spontaneous emission (ASE) and (2) by increasing the absorption efficiency of pump light. The gratings also serve as antireflective coatings for the extracting laser beam. To evaluate the potential for such coatings to improve laser performance, we calculated optical properties of a 2500 groove/mm, tantala-silica grating on a 1cm x 4cm x 8cm titanium-doped sapphire slab and performed ray-trace calculations for ASE and pump light. Our calculations show substantial improvements in efficiency due to grating ASE-coupling properties. For example, the gratings reduce pump energy required to produce a 0.6/cm gain coefficient by 9%, 20% and 35% for pump pulse durations of 0.5 {micro}s, 1{micro}s and 3{micro}s, respectively. Gratings also increase 532-nm pump-light absorption efficiency, particularly when the product slab overall absorption is small. For example, when the single-pass absorption is 1 neper, absorption efficiency increases from 66%, without gratings, to 86%, when gratings are used.
Date: April 16, 2010
Creator: Erlandson, A C; Britten, J A & Bonlie, J D
Partner: UNT Libraries Government Documents Department

Lethality Effects of a High-Power Solid-State Laser

Description: We study the material interactions of a 25-kW solid-state laser, in experiments characterized by relatively large spot size sizes ({approx}3 cm) and the presence of airflow. The targets are 1-cm slabs of iron or aluminum. In the experiments with iron, we show that combustion plays an important role in heating the material. In the experiments with aluminum, there is a narrow range of intensities within which the material interactions vary from no melting at all to complete melt-through. A paint layer serves to increase the absorption. We explain these effects and incorporate them into a comprehensive computational model.
Date: March 7, 2007
Creator: Boley, C; Fochs, S & Rubenchik, A
Partner: UNT Libraries Government Documents Department

On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers

Description: The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW beam breakup and the growth of multiple pulses. This can be both a detrimental effect, limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model, and the range of applicability of the latter is determined. The same technique is applicable to the study of spatial MI in solid state laser amplifiers and MI in non-uniform media.
Date: November 3, 2010
Creator: Rubenchik, A M; Turitsyn, S K & Fedoruk, M P
Partner: UNT Libraries Government Documents Department

Transparent Laser Ceramics at Lawrence Livermore National Laboratory (LLNL)

Description: LLNL has been using the largest transparent laser ceramics for the last two years in the solid-state heat capacity laser (SSHCL). The lab is very interested in extending the use of transparent ceramics to other laser applications. In this talk we will discuss work at the laboratory aimed at better understanding the sintering and the criteria needed for good ceramic transparency, the application of transparent ceramics in the SSHCL laser and possible new applications of tailored ceramics.
Date: June 28, 2007
Creator: Soules, T
Partner: UNT Libraries Government Documents Department

Production of Testing of Laser Crystals

Description: Lasers and nonlinear optical system are being developed to allow the construction of all solid state lasers with tunable output in the mid-infrared (3-5{micro}m). In these systems potassium titanyl phosphate (KTP) and its analogs (KTA, RTA and CTA) are used to construct Optical Parametric Oscillators (OPOs). In the past, large (5 mm x 5 mm x 15 mm) crystals of KTA, RTA and CTA have been difficult to obtain, and were costly as well. Also, the arsenate materials were limited in spectral range due to an AsO{sub 4} overtone in the 3.5 to 5.0 {micro}m region. There has also been interest in materials which self-OPO. This process is done by doping nonlinear materials with lasing ions. This effort investigated the development of mixed metal analogs of KTA, which would last and also suppress the AsO{sub 4} absorption overtones to allow more efficient mid-infrared OPO operation.
Date: January 21, 1999
Creator: Schmidt, T.
Partner: UNT Libraries Government Documents Department

Plasma electrode pockels cell for the National Ignition Facility

Description: The National Ignition Facility (NIF), now under construction at Lawrence Livermore National Laboratory, will be the largest laser fusion facility ever built. The NIF laser architecture is based on a multi-pass power amplifier to reduce cost and maximize performance. A key component in this laser design is an optical switch that closes to trap the optical pulse in the cavity for four gain passes and then opens to divert the optical pulse out of the amplifier cavity. The switch is comprised of a Pockels cell and a polarizer and is unique because it handles a beam that is 40 cm x 40 cm square and allows close horizontal and vertical beam spacing. Conventional Pockels cells do not scale to such large apertures or the square shape required for close packing. Our switch is based on a Plasma-Electrode Pockels Cell (PEPC). In a PEPC, low-pressure helium discharges (1-2 kA) are formed on both sides of a thin slab of electro-optic material. Typically, we use KH{sub 2}PO{sub 4 } crystals (KDP). The discharges form highly conductive, transparent sheets that allow uniform application of a high-voltage pulse (17 kV) across the crystal. A 37 cm x 37 cm PEPC has been in routine operation for two years on the 6 k.J Beamlet laser at LLNL. For the NIF, a module four apertures high by one wide (4x1) is required. However, this 4x1 mechanical module will be comprised electrically of a pair of 2x1 sub-modules. Last year (FY 97), we demonstrated full operation of a prototype 2x1 PEPC. In this PEPC, the plasma spans two KDP crystals. A major advance in the 2x1 PEPC over the Beamlet PEPC is the use of anodized aluminum construction that still provides sufficient insulation to allow formation of the planar plasmas.
Date: July 28, 1998
Creator: Alger, T.; Biltoft, P.; Boley, C. D.; Fochs, S.; Funkhouser, B. & Rhodes, M. A.
Partner: UNT Libraries Government Documents Department

New tunable lasers for potential use in LIDAR systems

Description: We discuss the optical and laser properties of two new tunable laser crystals, Ce:LiSrAlF{sub 6} and Cr:ZnSe. These crystals are unique in that they provide a practical alternative to optical parametric oscillators as a means of generating tunable radiation in the near ultraviolet and mid-infrared regions (their tuning ranges are at least 285-315 nm and 2.2-2.8 microns, respectively). While these crystals are relatively untested in field deployment, they are promising and likely to be useful in the near future.
Date: June 1996
Creator: Payne, S. A.; Page, R. H.; Marshall, C. D.; Schaffers, K. I.; Bayramian, A. J. & Krupke, W. F.
Partner: UNT Libraries Government Documents Department

Recent developments in Cr{sup 2+}-doped II-VI compound lasers

Description: Transition-metal-doped zinc chalcogenide crystals have recently been investigated as potential mid-IR lasers. Tetrahedrally-coordinated Cr{sup 2+} ions are especially attractive as lasants on account of high luminescence quantum yields for emission in the 2000-3000 nm range. {sup 5}E radiative lifetimes and emission cross sections are respectively {approximately}10 {mu}sec and {approximately}10{sup -18} cm{sup 2}. The associated absorption band peaked at {approximately}1800 nm enables laser-diode pumping of the Cr{sup 2+} systems. Laser demonstrations with ZnS:Cr and ZnSe:Cr (using a MgF{sub 2}:Co{sup 2+} laser pump source) gave slope efficiencies up to 30%. Excited-state-absorption losses appear small, and passive losses dominate. Tuning experiments with a birefringent filter evidence a tuning range covering at least 2280 - 2530 nm. Cr-doped laser samples can be produced by Bridgman growth, seeded physical vapor transport, or diffusion doping.
Date: September 1, 1996
Creator: Page, R.H.; DeLoach, L.D.; Schaffers, K.I., Patel, F.D.; Beach, R.J.; Payne, S.A.; Krupke, W.F. et al.
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

Femtosecond, Cr{sup 4+}:YAG laser

Description: Results from both a regeneratively-initiated and self-initiated, mode-locked CR.YAG laser which is tunable from 1.51 to 1.53 {mu}m are reported. One hundred and twenty femtsosecond, nearly transform-limited pulses have been generated with peak output powers of 45 kW. The stable, high peak power pulses and room temperature operation of this laser make it a very suitable alternative to the cumbersome, cryogenic mode-locked NaCl laser commonly used in both narrow bandgap semiconductor and optical communications research.
Date: August 1, 1994
Creator: Nathel, H.; Sennaroglu, A. & Pollock, C.R.
Partner: UNT Libraries Government Documents Department