Comparison of passively Q-switched LD side-pumped green laser by using Nd3+:YAG/Cr4+:YAG/YAG composite crystals of different initial transmissions

A diode-side-pumped passively Q-switched laser at 532 nm wavelength by Nd3+:YAG/Cr4+:YAG/YAG composite crystal is revealed for the first time. The output performances, including the threshold, slope efficiency, average power, pulse width, repetition rate and far field spot of lasers with Cr4+:YAG of different initial transmissions are experimentally compared. Under the pump power of 187.5 W, the Q-switched green laser with initial transmission of 85% obtains the maximum average power of 27.2 W and peak power of 7.8 KW. The laser with initial transmission of 65% obtains the pulse width of 59 ns. The initial transmission has significant effects on the output performances of passively Q-switched lasers.