Building a Raman laser pump source capable of generating flexible pulse durations while maintaining high spatial quality

Abstract

A detailed characterization of a Raman pump laser throughout the construction process is reported. Due to specific requirements for the pulsed Raman experiment, there were no commercially available pump lasers capable of meeting our specifications. The pump source must produce high energy pulses of 50mJ to 100mJ with variable duration centered at 200ns. To create this pump source, the pulses are gated from a CW source and then amplified with a high gain Nd:YAG amplification system. High spatial quality is also a necessity as the laser needs to be coupled into a small diameter waveguide functioning as the Raman cell. The laser was found to operate well, producing the required energy with the desired pulse flexibility. However, the amplification process induced spatial distortion that effectively produced a super Gaussian intensity distribution.