Dynamical equations of intra-cavity optical parametric oscillator synchronously pumped by SESAM mode-locked laser

By considering the intensity fluctuation mechanism of the fundamental laser, the rate-equation-based model for the CW mode-locking intra-cavity OPO (IOPO) is developed, which includes the behavior of the fundamental laser, the signal and idle light. In the derived model, the OPO nonlinear conversion is considered as a loss for the fundamental laser and thus the mode-locked signal or idle profile originates from the mode-locked fundamental laser. In experiment, the CW mode-locked Nd3+: GdVO4/KTA IOPO with semiconductor saturable absorber mirror (SESAM) is realized. The near-infrared signal light is obtained, which are generated from the IOPO pumped by CW mode-locked fundamental laser. The signal and fundamental spectra are experimentally measured, and then the wavelength of the idle light is estimated to be 3.31 μm. The theoretical values from the rate equations agree with the experimental results well. The developed model explains the behavior of the mode-locked IOPO, which is helpful to system optimization.