Abstract

Utilizing chirped pulse amplification, we have developed a 3-J 15-ps 1.06-μm laser source for the study of XUV lasers. The laser system consists of a Q-switched and mode-locked Nd:YAG oscillator configured to produce 220-ps pulses. The peak of the Q-switched pulse train is attenuated to 2 μJ and focused into a 47-cm single-mode optical fiber. Self-phase modulation in the fiber spectrally broadens and chirps the pulse. The output of the fiber is recollimated and relay imaged through a set of four Nd:YAG and three Nd: glass amplifiers. The narrowband Nd:YAG amplifiers significantly reshape the pulse and limit the output to 3 J in 100 ps. Compression to 15 ps is accomplished by two nearly parallel 1200-groove/mm gratings separated by 14 m. The 6.5- × 8.0-cm beam is focused in a line at ~65° incidence onto a grooved heavy metal target. The resulting plasma-produced soft x rays photoionize the atomic vapor which surrounds the target. With small angle adjustments of the final grating, synchronous traveling-wave pumping is achieved along the line focus. We have observed an increase in the optimum pressure for a small signal gain in the 108.9-nm Xe Auger system commensurate with the decrease in pulse length. Studies of Auger lasers in Cs and Kr and photoionization lasers K and Na are presented.

© 1988 Optical Society of America