Investigations and Comparisons of Active Q-Switching Laser Performances of Composite and Conventional Nd:$YVO_4$ Crystals with Electro-Optic Modulator

Actively Q-switched laser performances of composite and conventional Nd:$YVO_4$ crystals were investigated and compared with different Nd-doped concentrations of laser media and different repetition rates of electro-optic modulator. Both continuous-wave and actively Q-switched operations were realized experimentally. At an incident pump power of 7.69 W, the shortest pulse duration of 6.5 ns was obtained by the composite Nd(0.1 at.%):$YVO_4$/Nd(0.3 at.%):$YVO_4$/Nd(0.8 at.%):$YVO_4$ crystal at the repetition rate f=2 kHz. However, the composite Nd(0.1 at.%):$YVO_4$/Nd(0.5 at.%):$YVO_4$/Nd(1.0 at.%):$YVO_4$ laser achieved the maximum average output power of 687 mW at f=10 kHz and the largest single pulse energy of 144 μ J at f=2 kHz. Power saturation of the conventional Nd:$YVO_4$ crystal was shown during experiment, while no power saturation was observed on the composite Nd:$YVO_4$crystals, showing good thermo-mechanical performances.