Stimulated Brillouin Scattering(SBS) has been widely studied for various applications due to its useful properties of optical phase conjugation and pulse compression. For theoretical understanding, the partial differential equations on an SBS were numerically solved and the temporal and spatial pulse shapes reflected from the SBS mirror was analyzed. To achieve a short pulse duration and good spatial profile in a Nd:YAG laser system, two SBS mirrors were adopted. The first SBS mirror was used to compress the laser pulse duration from 14 ns to 4 ns, and the second one to compress the laser pulse duration from 4 ns to 1.5 ns and to compensate for the thermal lensing effect in the double pass amplifier. The output energy reached 0.5 J after passing through two-stage main amplifiers.
A Q-switched Nd:YAG laser, using a coupled oscillator and amplifier scheme with an SBS mirror, were investigated to shorten the long tail part of the pulse reflected by the SBS mirror, in which the acoustic grating could be quickly generated and sustained for a long time. When a neutral density filter which could control the coupled energy in this scheme, was 100%, the laser pulse with a fast falling time(4.3 ns) as well as a short pulse width(3.6 ns), was achieved.
A laser-plasma X-ray from solid Cu target and porous agar target using the Sinmyung high power Nd:glass, was measured. The high power Nd3+:phosphate glass laser consists of a Q-switched and mode-locked Nd:YLF oscillator, a pulse selector, a four-pass preamplifier, and five-stage main amplifiers. The laser pulse duration was 40 ps and the illuminated energy was from 1 to 2 J. The hard X-ray generated from a laser plasma was measured by a pin-hole camera, a flat-crystal spectrometer, and a photodiode established in a vacuum target chamber. The porous agar target, prepared by the research institute TRINITI in Russia through a collaboration, can contain various metallic components. It has a promising potential due to its capability of better laser absorption through porous structure which can produce X-ray more efficiently.
