Performance characterization of mid-infrared difference-frequency-generation in orientation-patterned gallium phosphide

We present detailed characterization of optical properties of the recently developed nonlinear material, orientation-patterned gallium phosphide (OP-GaP), by performing difference-frequency-generation experiments in the 2548-2782 nm wavelength range in the mid-infrared (mid-IR). Temperature and spectral acceptance bandwidth measurements have been performed to study the phase-matching properties of OP-GaP, and the dependence of nonlinear gain on the polarization of input incident fields has been investigated. The transmission of the OP-GaP crystal at the pump and signal wavelengths has been studied and found to be dependent on polarization as well as temperature. We have observed polarization-dependent spatial shift in the transmitted pump beam through the OP-GaP sample, indicating stress-induced birefringence in the crystal. We have also measured the damage threshold of the OP-GaP crystal to be 0.84 J/cm2 at 1064 nm.