Dual-RbTiOPO4 Optical Parametric Oscillator Producing Orthogonally Polarized 1.6- $\mu $ m Laser

We propose an efficient orthogonally polarized eye-safe laser at 1618 nm based on dual-RbTiOPO4 (RTP) optical parametric oscillator derived by an acousto-optic Q-switched Nd:YAG crystal laser. Two RTP crystals with the z-axis perpendicular to each other were adopted to make full use of different polarization parts of the fundamental light. Under an incident pump power of 10.5 W and a pulse repetition frequency of 15 kHz, the orthogonally polarized laser with an average output power of 1.4 W and a pulse width of 4.65 ns were achieved, giving an overall conversion efficiency of 13.3%. Both output power and conversion efficiency at 1.6 μm were improved significantly compared with that using two RTP crystals with the z-axis parallel to each other.