Efficient Raman shifting of picosecond pulses using BaWO4 crystal

Stimulated Raman scattering of picosecond pulses was investigated in a new BaWO4 Raman crystal and was compared with SRS in well known KGd(WO4)(2) and KY(WO4)(2) crystals. The first and second harmonic output of a mode-locked Nd:YAG laser system was used as a pump source. Due to transient behaviour, high value of BaWO4 steady state Raman gain is reduced by a factor of 2.5 for picosecond pump pulses (28 and 40 ps) but remains still higher than that in KGd(WO4)(2) crystal. Maximum first and second Stokes conversion efficiencies for BaWO4 in a single-pass arrangement were measured to be 30% and 15%, respectively. Measurements of a temporal pulse length showed that the first Stokes pulse was twice as short as the pump pulse. Barium tungstate can thus be considered as a unique Raman crystal for wide variety of pump pulse duration from nanoseconds to picoseconds for the generation of the frequency shifted Raman laser pulses. (C) 2000 Published by Elsevier Science B.V. All rights reserved.