Passively Q-switched YVO 4 Raman operation with 816 and 890 cm -1 shifts by respective Raman configurations

Passively Q-switched operation of Nd:YAP/Cr4+:YAG/YVO4 Raman lasers with 816 and 890 cm-1 shifts were demonstrated. A Cr4+:YAG/YAG composite crystal was utilized for the passively Q-switched operation. Using an output coupler with different transmittance at both first-Stokes wavelengths, the single first-Stokes waves at 1183.7 nm and 1194.6 nm were obtained in X(ZZ)X and X(YY)X Raman configurations, respectively. Under an absorbed pump power of 8.21 W, the maximum output power of 0.85 W and 0.76 W were achieved, corresponding to the conversion efficiency of 10.4% and 9.3%, respectively. Experimental results show that although the transmittance losses of both Stokes wavelengths were quite different, their thresholds were similar and very close to that of the passively Q-switched fundamental wave in the cavity. The pulse repetition frequency was mainly determined by the Raman conversion efficiency. These laser output characteristics have some reference value for the design of passively Q-switched Raman lasers.