Eye-safe optical parametric oscillator with pulse string output

A new method of generating 1.57 μm multi-pulse eye-safe laser based on optical parametric oscillator (OPO) has been developed. The pulse repetition rates, pulse numbers and pulse intervals could be regulated. By analyzing the threshold of the OPO and optimizing the resonator parameters, pulse string laser outputs with adjustable repetition rates were obtained. Each pulse string includes three micro-pulses, and their intervals were greater than 200 μs. It was observed that when the interval of the micro-pulse was 236 μs, the maximum output energy of the pulse string was 158 mJ with the single pulse width of 6 ns. The optical-optical efficiency of the OPO was 30.5%.