Efficient Compound-Cavity Eye-Safe KTP OPO at 1.57 μupm Pumped by an Electro-Optic Q-Switched Nd:YAG Laser

An efficient high-energy eye-safe optical parametric oscillator (OPO) based on a type-II non-critically phase-matched KTP crystal is demonstrated. The KTP OPO is pumped by a quasi-cw diode side-pumped electro-optic Q-switched Nd:YAG laser in a compound-cavity configuration. The maximum output energy of the signal wavelength at 1.57 μm is 66.5mJ, corresponding to an electrical-to-optical conversion efficiency of 4.47% and an optical-to-optical conversion efficiency of 12.1%. The pulse width (FWHM) is about 3.6ns with a peak power of 18.5MW. The output energy is insensitive to repetition rate and demonstrates good stability.