Ce/sup 3+/:LiCaAlF/sub 6/ crystal for high-gain or high-peak-power amplification of ultraviolet femtosecond pulses and new potential ultraviolet gain medium: Ce/sup 3+/:LiSr/sub 0.8/Ca/sub 0.2/AlF/sub 6/

To develop high-peak-power ultrashort pulse laser systems in the ultraviolet region, a large Ce/sup 3+/:LiCaAlF/sub 6/ (Ce:LiCAF) crystal, a tunable ultraviolet laser medium with large saturation fluence and broad gain spectrum width, was grown successfully with a diameter of more than 70 mm. To demonstrate high small signal gain, a four-pass confocal amplifier with 60 dB gain and 54 /spl mu/J output energy was constructed. Chirped pulse amplification (CPA) in the ultraviolet region was demonstrated using Ce:LiCAF for higher energy extraction. A modified bow-tie-style four-pass amplifier pumped by 100-mJ 266-nm 10-Hz pulses from a Q-switched Nd:YAG laser had 370-times gain and delivered 6-mJ 290-nm pulses. After dispersion compensation, the output pulses can be compressed down to 115 fs. This is the first ultraviolet, all-solid-state high-peak-power CPA laser system using ultraviolet gain media, and this demonstration shows further scalability of the Ce:LiCAF CPA system. Additionally, a new gain medium, Ce/sup 3+/:LiSr/sub 0.8/Ca/sub 0.2/AlF/sub 6/, with longer fluorescence lifetime and sufficient gain spectrum width over 18 nm was grown to upgrade this system as a candidate for a final power amplifier gain module.