Nd:YAG laser at 1112.3Â nm passively Q-switched by graphene-oxide saturable absorber

A passively Q-switched Nd:YAG laser at 1112.3 nm with graphene-oxide (GO) as a saturable absorber (SA) is presented. GO-SA is directly deposited in a long-wave-pass filter by vertical evaporation method. This filter effectively reduces the influence of pump light on the GO saturable absorption. The pulsed laser is realized at the threshold of 3.69 W. The repetition rate is tunable from 92 kHz to 220 kHz, and the maximum output power and the narrowest pulse width are 620 mW and 145 ns, respectively.