Efficient passively Q-switched Nd: KGW/Cr4+:YAG self-Raman laser

In this paper, the end-pumped passively Q -switched Nd: KGW/Cr 4+ :YAG self-Raman laser is designed to achieve high efficient operation. Concave-plane linear cavity is adopted to obtain the shortest cavity length, and long Nd: KGW crystal of 40 mm is used in the experiment. Cr 4+ :YAG crystals of high initial transmittances ( T 0 = 96% and 92%) are utilized to realize efficient and stable passively Q -switched operation. The passively Q -switched Nd: KGW/Cr 4+ :YAG self-Raman laser is theoretically investigated at 1181 nm corresponding to the Raman mode of 901 cm − 1 shift in Nd: KGW crystal. With Cr 4+ :YAG crystal of the initial transmittance T 0 = 96%, the maximum output power of 0.624 W at 1181 nm is achieved experimentally with optical-to-optical efficiency of 13.9%, which is the highest efficiency reported for passively Q -switched Nd: KGW self-Raman laser.