R.J. Beach

DPAL: A new class of lasers for cw power beaming at ideal photovoltaic cell wavelengths

The new class of diode pumped alkali vapor lasers (DPALs) offers high efficiency cw laser beams at wavelengths which efficiently couple to photovoltaic (PV) cells: silicon cells at 895 nm (cesium), and GaAs cells at 795 nm (rubidium) and at 770 nm (potassium). DPAL electrical efficiencies of 25–30% are projected, enabling PV cell efficiencies ∼40% (Si) and ∼60% (GaAs). Near‐diffraction‐limited DPAL device power scaling into the multi‐kilowatt regime from a single aperture is projected. The potential application to power beaming propulsion to raise satellites from LEO to Geo is discussed.

Prospects for measurement of rapid equilibrium changes and electron fluctuations using a high repetition rate Thomson scattering diagnostic

Recent technological developments make a laser Thomson scattering diagnostic, operating in the incoherent electron scattering regime, a good candidate to accomplish measurements of fast electron dynamics (i.e., fast equilibrium changes, turbulence, and electron fluctuations) in high temperature plasmas. Pulse repetition rates for current generation Thomson scattering diagnostics have been limited to about 100 Hz, with the possible exception of “burst” modes in which multiple laser systems provide a limited sequence of closely spaced pulses. To overcome this limitation in laser capability, we propose that recent advances in compact, high power, diode-pumped solid state lasers be applied to a fast Thomson scattering diagnostic for fusion research. To illustrate the possibilities, we present an overview of a diagnostic system designed for the Madison Symmetry Torus reversed field pinch. The operational goal for this single-laser system is to measure Te, ne, and pe with a measurement rate of at least 10 kHz...

The Mercury laser: a diode-pumped, gas-cooled Yb:S-FAP solid-state laser

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.

High-power dual-rod Yb:YAG laser

We describe a diode-pumped Yb:YAG laser that produces 1080 W of power cw with 27.5% optical optical efficiency and 532 W Q-switched with M(2)=2.2 and 17% optical-optical efficiency. The laser uses two composite Yb:YAG rods separated by a 90 degrees quartz rotator for bifocusing compensation. A microlensed diode array end pumps each rod, using a hollow lens duct for pump delivery. By changing resonator parameters we can adjust the fundamental mode size and the output beam quality. Using a flattened Gaussian intensity profile to calculate the mode-fill efficiency and clipping losses, we compare experimental data with modeled output power versus beam quality.

Stimulated Raman scattering in Sr/sub 5/(PO/sub 4/)/sub 3/F laser amplifiers

Summary form only given. Ytterbium-doped Sr/sub 5/(PO/sub 4/)/sub 3/F (S-FAP) has been shown to be a promising laser material for medium-power, high-energy applications such as diode pumped solid-state laser oscillator and amplifier systems. In large-scale amplifier systems where intensities of several GW/cm/sup 2/ are typical, nonlinear optical phenomena such as stimulated Raman scattering (SRS) need to be considered. For our purposes, the error in the calculated gain coefficient is too large (nearly 50%, so we conducted an experiment that directly measured the Raman gain coefficient. A 1053-nm pump beam generated spontaneous Raman light, which was then amplified within the three crystals through stimulated Raman processes. The crystals are separated to prevent oscillation due to Fresnel reflections. Because the 1053-nm pump beam and the SRS signal are collinear after exiting the last crystal, the colors were separated using a prism, and the SRS light detected.

High-resolution, near-diffraction-limited tunable solid-state visible light source using sum-frequency mixing

Summary form only given. Our first cladding-pumped fiber amplifier (CPFA) was designed around double-clad Yb:silica fiber from Polaroid and a 10 Watt semiconductor diode laser P6 pump diode array and produced over 2 Watt output power at 1064 nm. This master-oscillator-power-amplifier architecture provided high power and narrow linewidth simultaneously.

2150-2800 nm Coverage And Diode Pumping With ZnSe:Cr/sup 2+/ Lasers

The other end was Brewster-cut to its axis and had AR coating. The output tuning range from 675 nm to 1015 nm was obtained as shown in Fig. 2 with the peak power up to 400 mW at a 5-W pumping level (2.5 W absorbed). Because direct coating on the crystal did not sacrifice bandwidth, we can simplify the configuration, and reduce the number of optics and losses in the cavity. These advantages contributed to a lower threshold of lasing and easier alignment. In conclusion, broad-band tunability was demonstrated in a compact Ti:sapphire laser which was pumped by a laser-diode-pumped intra-cavity frequencydoubled Nd:YVO, laser. Its smaller than a notebook size and simpler configuration without any sacrifice of tunability will be attractive for new applications of tunable lasers. *Institute for Molecular Science (IMS), Myodaiji, Okazaki 444, JAPAN 1. r. Izawa, M. Maeda, N. Yamamura, R. Uchimura, T. Yakuoh, N. Sarukura, Z . Liu, Y. Segawa, Technical Digest of Conference on Laser and Electro-optics (OSA), Baltimore, 40 (1995). IP. F. Moulton, J. Opt. Soc. Am. B 3, 125 (1986). 2.