Optical-to-optical conversion efficiencies of as high as 32% with a slope efficiency of 44% were obtained with a novel diode-bar, side-pumped laser cavity design. A slab geometry with a single, high-angle-of-incidence reflection was used to extract gain from near the pump face of a Nd:YVO(4) bar that absorbed strongly at the pump wavelength. Small-signal gains of greater than 8 cm(-1) and pulse energies of as much as 3.2 mJ were obtained in an almost TEM(00) mode. Aperturing effects by the laser rod were found to limit the effects of nonuniform gain on the laser mode.

A High Efficiency Diode-Pumped Nd:YVO 4 Slab Laser

Optical phase conjugation: principles, techniques, and applications

Highly efficient 1-μm continuous-wave laser emission in 3-mm-thick, 0.5- and 1.0-at. % Nd:GdVO4 crystals longitudinally pumped at 879 nm into the laser emitting level is reported. Under Ti:sapphire pumping, the slope efficiency in absorbed power is ~80% for both crystals, while the slope efficiency, the optical-to-optical efficiency (at 1700-mW pump power), and the laser threshold in incident power are 79%, 78%, and 31 mW for 0.5-at. % Nd and 80%, 77%, and 40 mW for 1.0-at. % Nd, respectively. The slope efficiency is close to the quantum defect limit, the difference being fully accounted for by the residual optical losses. Under 879-nm diode laser pumping, the slope efficiency and the optical-to-optical efficiency in absorbed power of the 0.5-at. % Nd:GdVO4 crystal are 60% and 53%, owing to poorer superposition of the pumped and the laser mode volumes.

Highly efficient 1063-nm continuous-wave laser emission in Nd:GdVO4

We describe the operation of a self-starting Nd:YAG laser oscillator incorporating a design in which laser oscillation occurs by means of diffraction from spontaneously generated three-dimensional gain gratings produced by spatial hole burning in the Nd:YAG amplifier. The transient onset and spectral selectivity of the gain gratings produce an output with energy of 600 mJ in a 10-ns single-longitudinal-mode pulse at 10 Hz. The self-adaptation of the gain gratings produces compensation of intracavity phase distortion. A transient numerical modeling of the nonlinear resonator gives good agreement with the experimental system and also provides insight into the temporal dynamics of the gain grating.

Self-adaptive solid-state laser oscillator formed by dynamic gain-grating holograms.

The experimental performance of a gain-switched Ti:sapphire laser oscillator pumped by a frequency-doubled Q-switched Nd:YAG laser system is presented for a variety of operating conditions. A theoretical model developed for this oscillator predicts well its performance. The observed curved input-output energy plots for the oscillator result from the kinetics of gain switching and fluorescence decay during the gain buildup period. Fluorescence decay also produces observed oscillator thresholds higher than those normally predicted by the standard gain-equals-loss condition. Gain-switched parasitic modes, with a higher threshold but shorter round-trip time than the resonator mode, cause the resonator mode to oscillate only over a finite range of pump energies. Spectroscopic investigations show that the Ti:sapphire cross-section spectrum is well fit by a Poisson distribution, giving a peak cross section of 3*10/sup -19/ cm/sup 2/ for the pi polarization. >

Characteristics and kinetics of laser-pumped Ti:Sapphire oscillators

Continuous-wave Nd:YVO4 grazing-incidence laser with 22.5 W output power and 64% conversion efficiency

We report the operation of Nd:YAG ring laser resonators formed by diffractive coupling from a gain volume hologram written in a Nd:YAG amplifier. Stable diffraction-limited output in a TEM00 mode is demonstrated in a Nd:YAG system with thermal lensing and without the requirement of spatial mode control.

Holographic laser resonators in Nd:YAG.

High-reflectivity four-wave mixing by gain saturation in a Nd:YAG laser amplifier is demonstrated. With a four-pass geometry, the phase-conjugate reflectivity of a Q-switched pulse (18-ns duration) is ∼2500, and for a long pulse (relaxation oscillation duration ∼100 μs) it is ∼30. Temporal and energy characteristics of the conjugate beam are presented. A phase-conjugate Nd:YAG TEM00 laser resonator is also produced in which the Nd:YAG rod is simultaneously the laser gain medium and the phase-conjugating device.

High-reflectivity four-wave mixing by gain saturation of nanosecond and microsecond radiation in Nd:YAG.

Spatial characteristics of a laser oscillator formed by optically-written holographic gain-grating

High-phase-conjugate reflectivities of >800% have been achieved through degenerate four-wave mixing in a cw diode-side-pumped Nd:YVO4 amplifier. Reflectivity curves are shown as a function of input pump-beam intensity for three values of small-signal amplifier gain, and comparison is made with a numerical simulation.

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G.J. Crofts

Papers

Continuous-wave Nd:YVO4 grazing-incidence laser with 22.5 W output power and 64% conversion efficiency

Holographic laser resonators in Nd:YAG.

High-reflectivity four-wave mixing by gain saturation of nanosecond and microsecond radiation in Nd:YAG.

Spatial characteristics of a laser oscillator formed by optically-written holographic gain-grating

High-phase-conjugate reflectivity (<800%) obtained by degenerate four-wave mixing in a continuous-wave diode-side-pumped Nd:YVO(4) amplifier.