Abstract

Yttrium orthosilicate (YOS) is a biaxial crystal that can be grown in boules of good laser optical quality with Nd³⁺ dopings of at least 2.0 × 10²⁰/cc. The 1.074-µm transition has a third as large a peak transition cross section as the Nd: YAG 1.064-µm line. At the above doping, the inversion lifetime is 180 µsec. The R_T of YOS is one-fourth that of YAG. The 801-µm absorption line in YOS is twice as wide as YAG’s corresponding 808-nm line. We have conducted a side-by-side lasing comparison of Nd:YOS Nd:YAG using 0.25 in. diameter, 2.3-in. long laser rods. The YAG rod had a doping of 1.38 × 10²⁰/cc. The YOS rods were fabricated to match the YAG rod and were doped to 2.0 × 10 /cc. A Kigre water cooled two-Xe lamp pump cavity head was used. The system was powered by the oscillator supply of a DCR3. The cavity length was 30 cm, and 75-cm radius of curvature mirrors were used at both ends. In free running operation, the YOS outputed up to 1.8 J/pulse and was rep-rated to 30-W average power. The YAG reached just under 1.1 J and 19-W average power in the same pumping conditions. The greater performance of the YOS can be explained by the higher doping. Rigrod analysis of the free running performance shows that the YOS system has nearly half the loss as the YAG system (3.5 vs 6.8%). A KD^*P Pockels cell was used to O-switch both laser setups. Over 0.5 J in 10 ns (FWHM) was obtained in YOS. Coating damage occurred ~0.6 J. The YAG performance was limited to 200 mJ due to prelasing.

© 1991 Optical Society of America