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Magneto-rheological finishing techniques have been applied to Yb:S-FAP and Ti:sapphire crystals to compensate for submillimeter distortions; improving the transmitted wavefront (10times) and increasing the availability of large aperture parts (>10 cm).

We have commissioned a turnkey 500 mJ, 10 Hz front end laser. The system delivers temporally and spectrally tailored pulses to correct signal distortions within itself or subsequent amplifiers from single longitudinal mode to 250 GHz RF bandwidth.

The Mercury laser project is part of a national inertial fusion energy program in which four driver technologies are being considered including solid-state lasers, krypton fluoride gas lasers, Z-Pinch and heavy ions. Mercury's operational goals of 100 J, 10 Hz, 10% efficiency in a 5 times diffraction limited spot will demonstrate the critical technologies required for scaling the system to the multi-kilojoule level. Five one hour runs were conducted to assess system stability and reliability; energy fluctuations during the 55 J operations showed a 0.6% rms deviation. Current beam quality during average power operation is approximately 10 times diffraction limited. In the future, active wavefront control, and corrector plates for steady state thermal distortions will be implemented to achieve the 5 times diffraction limited spot.

The Titan laser, designed to produce up to 600 J with pulses of 0.4-200 ps, has begun initial target shots. Coupled with a kJ long-pulse beam, Titan will support high-energy-density physics research at LLNL.

A novel scheme is described that overcomes parametric-fluorescence limitations of quasi-phase-matched, optical-parametric chirped-pulse amplification to produce millijoule pulse energies at 1053 nm. High gain, beam quality, bandwidth, and extreme prepulse contrast are demonstrated.

We report on the design of a novel, high energy (200 J), short pulse (150 fs) laser that is based on hybrid, broadband optical parametric chirped pulse amplification (OPCPA) and mixed silicate and phosphate Nd:glass amplification.

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 discussed below, we propose that a gas-cooled, diode-pumped Yb:S-FAP laser can provide new paradigm for fusion laser technology leading into the next century.

Summary form only given. Optical parametric chirped pulse amplification (OPCPA) offers several advantages when compared to regenerative chirped pulse amplification using Ti:sapphire or Cr:LiSAF. These advantages include low cumulative nonlinear phase (B-integral), greater wavelength flexibility, and high gain achieved without the use of gated electro-optic modulators and multipass amplification. High-energy OPCPA systems pumped by large aperture, low repetition rate glass laser systems have produced up to 0.5 J of amplified stretched pulses, subsequently recompressed to 300 fs. However, OPCPA using commercially available Q-switched pump lasers have, to date, only produced 600 /spl mu/J of amplified signal with a pump-to-signal conversion efficiency near 0.3 %. This low efficiency limits the attractiveness of OPCPA to facilities with high energy, shorter pulse pump lasers. We report chirped pulse amplification of broadband 1054 nm pulses to 31 mJ by single passing only 40 mm of gain material pumped by a commercial Q-switched laser, with a pump to signal conversion efficiency of 6%.

Summary form only given. The physical robustness of the GdCOB family of nonlinear crystals has attracted interest in these materials in applications involving high-average power. Large crystal growth of these materials is relatively easy, they readily and quickly accept a high quality optical polish, and are non-hygroscopic. High average power conditions encountered in intracavity frequency conversion makes desirable an intracavity converter crystal that has low angular and temperature sensitivities. We report values of the thermal sensitivity, /spl beta//sub T/=(/spl delta//spl Delta/k//spl delta/T), and angular sensitivity, /spl beta//sub /spl theta//=(/spl delta//spl Delta/k//spl delta//spl theta/), for LBO, GdCOB, and LaCOB as determined from experiment.

Summary form only given.Gas-cooled, diode-pumped, Yb:crystal lasers are envisioned to be the next-generation inertial confinement fusion (ICF) solid state laser system producing high energy per pulse at modest rep-rates. Innovative solutions for building ICF lasers with high repetition rate and efficiency include: trading the flashlamps for large, low-cost laser diode arrays; using Yb:crystals for greater energy storage and thermal conductivity than Nd:glass; and employing near-sonic helium for cooling of the laser slabs.

Summary form only given. Yb-doped Sr/sub 5/(PO/sub 4/)/sub 3/F (S-FAP) has already been demonstrated as an ideal laser material for medium power applications in a diode-pumped solid-state laser oscillator and high repetition rate amplifier system. Ytterbium has a simple electronic structure in the near infrared leading to a low quantum defect, excited state absorption, and nonradiative decay. S-FAP lasers at 985 nm can be efficiently pumped by diodes at 900 nm and have the added advantage of a low quantum defect (0.09) yielding efficient diode pumped operation. In addition, the advent of an efficient diode-pumped, doubled S-FAP laser at 492.5 nm represents an attractive blue light source.