200 ps pulse generation at 1180 nm with a SrWO4 Raman crystal pumped by a sub-nanosecond MOPA laser system

Abstract

We are reporting Raman conversion experiments with a SrWO4 crystal in a single-pass traveling-wave setup. As a pump source we employed a master oscillator power amplifier (MOPA) laser system at 1064 nm, delivering 200 µJ, 500 ps long pulses at a 9 kHz maximum repetition rate with limited diffraction beam quality. At 2 kHz we obtained up to 45 µJ pulse energy and 200 ps pulse duration at 1180 nm, with a conversion efficiency of 22%. Up to the maximum incident average pump power of 1.35 W no serious beam quality degradation was observed, and we measured a factor M2 ⩽ 1.5 for the Raman shifted beam.