Analysis of time domain characteristics of high energy nano-second optical parametric oscillator

The time domain characteristics of high energy nano-second optical parametric oscillator are analysed with discrete-approximation method, and the procedure of signal wave is modeled. Different pulse widths result in varied build-up times and optimum crystal lengths, which dominate the efficiency of pulse pump. When the pump energy remains fixed, there is an optimum pulse width for the pump wave, with which the highest efficiency could be expected. In addition, for the first time, the analytic solutions for both small and large signal gain conditions are supplied with the discrete-approximation method. We also give the equations for the build-up time, the optimum crystal length and the efficiency, both in accurate form and simple form for estimation, and finally apply the results to the experiments.