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 M<sup>2</sup> is better than 1.8. The tunability of 3~5 μm can be achieved by changing the angle of the ZGP crystal.
© 2011 Chinese Optics LettersPDF Article