Mid-infrared optical parametric oscillator based on ZnGeP2 pumped by 2- \mum laser

Abstract

We present a 3~5 μm optical parametric oscillator (OPO) based on ZGP pumped by KTP OPO 2.1-μm laser. The tuning curves of ZGP OPO are calculated. The x 6 x 18 (mm) ZGP crystal, whose end faces are antireflection coated at 2.1 and 3.7~4.6 μm, is cut as Θ =53.5o, Φ =0o. When the pump power of 2.1-μm polarized laser is 15 W at 8 kHz, 5.7-W output power and 46.6% slope efficiency are obtained with a ZGPtype I phase match. Central wavelengths of the signal and idler lasers are 4.10 and 4.32 μm, respectively. Pulse duration is about 27 ns. Beam quality factor M2 is better than 1.8. The tunability of 3~5 μm can be achieved by changing the angle of the ZGP crystal.