High-power HgGa2S4 optical parametric oscillator pumped at 1064nm and operating at 100 Hz

The defect chalcopyrite crystal HgGa2S4 has been employed in a 1064-nm pumped optical parametric oscillator operating at 100 Hz, to generate approximate to 5 ns long idler pulses near 4 mu m with energies as high as 6.1 mJ and average power of 610 mW. At crystal dimensions comparable to those available for the commercial AgGaS2 crystal, operation of the 1064-nm pumped HgGa2S4 OPO is characterized by much lower pump threshold and higher conversion efficiency, with the most important consequence that such a device might become practical at pump levels sufficiently lower than the optical damage threshold.