Nd:YAG oscillator with pulse duration of 240 ns and pulse repetition frequency up to 90 kHz

Conventional Nd:YAG lasers typically suffer from unstable output at pulse repetition frequency beyond 20 kHz due to low stimulated emission cross-section and insufficient gain recovery time. We demonstrate a Q-switched Nd:YAG laser featuring a stable output with a long pulse duration of 240 ns and a high repetition frequency up to 90 kHz. We use Nd:YAG as a gain medium to obtain long-pulse duration, high brightness pump to alleviate the instability during Q-switching at high repetition frequency, and birefringence compensation to eliminate the severe birefringence effect caused by high pumping intensity. The device delivers stable ultra-violet output across 20 to 90 kHz, achieving