Optical parametric oscillation in quasi-phase-matched GaAs

We demonstrate an optical parametric oscillator (OPO) based on GaAs. The OPO utilizes an all-epitaxially-grown orientation-patterned GaAs crystal that is 0.5 mm thick, 5 mm wide, and 11 mm long, with a domain reversal period of 61.2 mum.. Tuning either the near-IR pump wavelength between 1.8 and 2 mum or the temperature of the GaAs crystal allows the mid-IR output to be tuned between 2.28 and 9.14 mum, which is limited only by the spectral range of the OPO mirrors. The pump threshold of the singly resonant OPO is 16 muJ for the 6-ns pump pulses, and the photon conversion slope efficiency reaches 54%. We also show experimentally the possibility of pump-polarization-independent frequency conversion in GaAs. (C) 2004 Optical Society of America.