Cr2+:ZnS Saturable Absorber Passively Q-Switched Ho:LuVO4 Laser**Supported by the National Natural Science Foundation of China under Grant Nos 61308009, 61405047 and 50990301, the China Postdoctoral Science Foundation Funded Project under Grant No 2013M540288, the Fundamental Research Funds for the Central Universities under Grant Nos HIT.NSRIF.2014044 and HIT.NSRIF.2015042, the Science Fund for Outstanding Youths of Heilongjiang Province under Grant No JQ201310,

Abstract

We report a cw Tm:YAP laser resonantly pumped Ho:LuVO4 laser in passively Q-switched (PQS) mode with Cr2+:ZnS as a saturable absorber (SA). The influence of different transmittances of the output coupler on laser output performance is analyzed. With T = 50%, the maximum PQS average output power of 2.3 W is obtained, corresponding to the slope efficiency and the optical–optical conversion efficiency are 35.1% and 19.8%, respectively. Also, the minimum pulse width of 100 ns is achieved at the maximum pulse repetition frequency of 34.2 kHz. When the maximum cw output power is 2.7 W, the beam quality factor of the horizontal direction Mx2 = 1.04 and the vertical direction My2 = 1.10 are obtained. In addition, the central wavelength of the laser output remains to be 2057.5 nm with the output coupler transmittances of 50% and 60% in both cw and PQS operations. The results show that the Cr2+:ZnS can be used as an SA in a Ho:LuVO4 laser around 2-μm wavelength.