Performance analysis of a 500 Hz non-critically phase-matched KTP-based optical parametric oscillator–amplifier system

High-repetition-rate 1.57 μm lasers are of great importance in both industrial and military applications. In this work, an optical parametric oscillator (OPO)–optical parametric amplifier (OPA) system was designed and constructed, achieving high-beam-quality and high-stability 1.57 μm pulsed laser output at a repetition rate of 500 Hz. The system employs an electro-optically Q-switched, laser diode side-pumped all-solid-state Nd:YAG oscillator and amplifier to generate high-beam-quality 1064 nm laser radiation, which serves as the pump source for a type-II noncritical phase-matched potassium titanyl phosphate crystal to produce the signal light. By integrating the Nd:YAG oscillator and amplifier, OPO oscillator, time-delay system, and OPA amplifier, a final OPA pulsed laser output at 500 Hz was achieved with a single-pulse energy of 7.91 mJ, a beam quality factor of M2=2.57, high stability, and excellent beam quality. This high-repetition-rate, high-stability optical parametric amplification laser shows promising potential for applications such as LIDAR.