Abstract
Recent progress of short-pulsed high-intensity Nd YAG lasers and their application to generation of coherent vacuum ultraviolet radiation are reviewed. For a nanosecond operation, use of an unstable resonator employing a variable-reflectivity-mirror greatly improves an output performance of a Q-switched Nd YAG laser. The smooth, large-sized and flat-topped TEM00 output beams are ideal for nonlinear frequency conversion. The technique of injection seeding also improved efficiency of the frequency conversion and stability, avoiding random spikes in a pulse and optical damage of optics due to mode beating. For a picosecond operation, simultane-ous Q-switching and mode locking increase the energy in a single pulse by several orders of magnitude, compared to a continuous-wave actively mode-locked Nd : YAG laser. There has been also considerable progress in the development of Nd YAG amplifier by introducing regenerative amplification technique. These progress of short-pulsed high-intensity Nd YAG laser technology allows the development of new high-power coherent sources in vacuum ultraviolet region.
