Efficient Raman shifting of picosecond pulses using BaWO4 crystal

Abstract Stimulated Raman scattering of picosecond pulses was investigated in a new BaWO 4 Raman crystal and was compared with SRS in well known KGd(WO 4 ) 2 and KY(WO 4 ) 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 BaWO 4 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(WO 4 ) 2 crystal. Maximum first and second Stokes conversion efficiencies for BaWO 4 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.

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