Diode-end-pumped passively Q-switched blue laser with Nd:YAG/YAG/Cr4+:YAG/YAG composite crystal

For obtaining efficient passively Q-switched laser at 473 nm, an Nd:YAG/YAG/Cr4+:YAG/YAG composite crystal and a coupled cavity were employed to reduce the thermal lens effect and enable the laser system operating on high pumped power. In our experiment, the maximum average output power of 0.81 W was obtained with the repetition rate of 28.5 kHz and the pulse width of 104 ns at the pumped power of 9.79 W, corresponding to an optical-to-optical conversion efficiency of 8.27%.