Midinfrared optical parametric oscillator based on the wide-bandgap BaGa4S7 nonlinear crystal

The orthorhombic biaxial crystal BaGa4S7 has been employed in a 1064 nm pumped optical parametric oscillator generating <6 ns long idler pulses with energies as high as 0.5 mJ at 6.217 mu m and average power of similar to 50 mW at 100 Hz. Notwithstanding the relatively low nonlinearity, similar to 3 times above threshold operation has been achieved at pump intensities more than 5 times below the crystal surface damage limit. (C) 2012 Optical Society of America