Evolution Of The Raman Beam Quality In A Folded-Coupled-Cavity Nd:Yvo4/Yvo4 Raman Laser

An end-pumped actively Q-switched Nd:YVO4/YVO4 Raman laser with a folded coupled cavity is demonstrated to study the evolution of Raman beam quality. The theoretical mechanism of the beam cleanup effect of stimulated Raman scattering is analyzed. The beam quality (M-2) of the Raman beam and the fundamental beams before and after the Raman conversion are measured experimentally. The results show that with the incident pump power increasing, the M-2 of the fundamental beam increases from 1.85 to 3.08, while the M-2 of the Raman beam increases from 1.21 to 1.69. The beam quality of the Raman laser and its degradation are better than that of the fundamental laser. (C) 2019 Optical Society of America