M. J. Damzen

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

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.

High-efficiency laser-pulse compression by stimulated Brillouin scattering.

Highly efficient compression of laser pulses down to 1 nsec in duration by stimulated Brillouin scattering has been demonstrated. Compression ratios of ~10 and energy-conversion efficiencies >70% have been produced. Several compressor systems have been investigated, including the use of tapered waveguides, long-focal-length geometries, and generator-amplifier systems.

Investigation of multipass geometries for efficient degenerate four-wave mixing in Nd:YAG

Degenerate four-wave mixing in the saturable gain of a flash-lamp-pumped Nd:YAG amplifier has been investigated. Three different geometries are examined in which the probe beam experiences (a) one pass, (b) two passes, and (c) four passes of the four-wave interaction region. It is found that multipassing the gain medium has a dramatic effect on the efficiency of the process, with a phase-conjugate reflectivity of 2500 and a conjugate energy extraction efficiency of greater than 200% demonstrated.

Phase conjugate reflectivity and diffraction efficiency of gain gratings in Nd:YAG

Abstract It is shown that gain gratings can be used as efficient phase conjugate and diffractive optical elements. Experimental results are presented of saturable gain four-wave mixing in a Nd:YAG amplifier using orthogonally polarised pump beams of pulse duration 16 ns. Phase conjugate reflectivity and diffraction efficiency are measured for both the reflection and transmission grating cases. Results show a higher efficiency for the transmission geometry. Transient (experimental results are comjpaed to a steady state theory.

High repetition rate Q-switching performance in transversely diode-pumped Nd doped mixed gadolinium yttrium vanadate bounce laser.

Up to 700 kHz high repetition active Q-switching was achieved with a pulse-width of < 40 ns by using a diode-side-pumped Nd:Gd_xY_1-xVO₄ bounce amplifier. The average output power of 17.5 W was obtained at a pump power of 41 W.

The thermo-lensing effect in a grazing incidence, diode-side-pumped Nd:YVO4 laser

Abstract The thermal lensing effect induced by high-power diode pumping in the grazing incidence side-pumped Nd:YVO4 laser geometry is numerically modeled and analyzed. The 3D temperature distributions and the correspondent thermally induced lens in Nd:YVO4 crystal are calculated for the straight and zig-zag paths of the laser beam.

High repetition rate Q-switching of high power Nd:YVO4 slab laser

A high power, diode-side-pumped Nd:YVO4 laser with a grazing incidence cavity geometry was acousto-optically Qswitched at frequencies up to 500 kHz. In CW operation, the laser output power was 16.4 W at 30.5 W of diode pump, corresponding to optical conversion efficiency of 53.8%. In Q-switching operation, measurements were made of average output power, pulse duration, pulse energy and peak power as a function of Q-switching frequency. At 200 kHz repetition rate and pump power 30 W, the laser output had average power 15.9 W (optical conversion efficiency 53%), pulse duration 15 ns, pulse energy 80 lJ and peak power 5.3 kW. A numerical modeling of the Q-switched laser was performed and results compared with experimental data. 2003 Published by Elsevier Science B.V.

Holographic laser resonators in Nd:YAG

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 TEM(00) mode is demonstrated in a Nd:YAG system with thermal lensing and without the requirement of spatial mode control.

Powerful visible (530–770 nm) luminescence in Yb,Ho:GGG with IR diode pumping

Powerful visible luminescence in a Gadolinium Gallium Garnet (GGG) crystal, co-activated with Yb3+ (~15 at.%) and Ho3+ (~0.1 at.%) ions, is investigated under CW laser diode pumping (lambda = 938 and 976 nm). The main visible emission band is observed in the green with its peak at lambda ~540 nm) and measured to be about 10% with respect to Yb3+ IR luminescence (lambda ~1000 nm). Red (lambda ~650 nm) and near-IR (lambda ~755 nm) emission bands are also observed but are weaker (about 3-5%). Analysis of the crystal absorption and luminescence spectra allows one to conclude that Yb3+ - Ho3+ stepwise up-conversion is the mechanism explaining the phenomenon. Ho3+ ions embedded in the crystal in small concentration are shown to form an effective reservoir for energy transferred from the excited Yb3+ subsystem and to be an efficient source of the visible emission.

High-reflectivity four-wave mixing by gain saturation of nanosecond and microsecond radiation 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.