Minimizing the risk of laser damage due to transverse stimulated Raman scattering in large-aperture KDP/DKDP plates

The transverse spontaneous Raman scattering in a configuration analogous to the geometry of a large-aperture potassium dihydrogen phosphate polarization rotator plate for inertial confinement fusion-class lasers is investigated. The experimental setup enabled effectively measuring the transverse Raman scattering in 360° around the beam propagation direction for any crystal optic-axis (OA) alignment. Results reveal the angular dependence of the transverse Raman scattering signal as a function of (1) the angle between the OA and the pump-beam propagation and (2) the angle of the X-Y axis around the OA. These results enable the consideration of optimal crystal cut designs for specific applications.