Pulse width stretched Q-switched Nd:YAG green laser based on a multi-pass cavity

We present a compact pulse width stretched nanosecond pulse Nd:YAG green laser based on a multi-pass cavity (MPC). The pulse widths were stretched from adjustable regime 110-260 ns to 460-600 ns by changing from single to multi-pass operation at the pulse repetition rate of 10 kHz. At a typical pulse width of 460 ns, an average output power of 6.5 W was successfully achieved. The 532 nm output power and pulse width versus the 1064 nm pump power were simulated. The calculated results were well consistent with experimental data. Such nanosecond pulse lasers are interesting for both industrial and scientific applications, for example laser damage experiment for some new materials.