A continuous-wave vortex Raman laser with sum frequency generation

Sum frequency generation of the fundamental and Stokes fields within an intracavity self-Raman vortex laser is demonstrated in a linear resonator configuration. In this system, the sum frequency field exhibits different spatial profiles in the near and far fields, and a time-varying topological charge which varies between values of +2 and 0. We present a theoretical model which supports these experimental observations.