Continuous Wavelength Tuning Across 3.9–12.0 μm From a 1040-nm-Pumped Optical Parametric Oscillator Based On Orientation-Patterned GaP Grown On GaAs

Orientation-patterned gallium phosphide [1] (OPGaP) is a wide-bandgap material enabling two-photonabsorption-free pumping using 1040-nm Yb-lasers, and such OPGaP optical parametric oscillators (OPOs) have been applied in Fourier-transform [2] and dual-comb [3] spectroscopies across the 5–12-μm molecular fingerprint region. Hetero-epitaxial growth of GaP on orientation-patterned gallium arsenide (OPGaAs) templates has been developed [4] , to mitigate issues with GaP substrates, but no nonlinear frequency conversion has yet been demonstrated. Here we report the first efficient frequency conversion in OPGaP-on-OPGaAs. OPGaP layers up to 1.2-mm thick were grown by hydride vapor-phase epitaxy (HVPE) on a 3-inch MBE-grown OPGaAs template. Several multi-grating and fan-out crystals of lengths 1.1 mm and 2.9 mm were diced from the wafer and polished into plane-parallel chips, and a broadband anti-reflection coating was applied to both faces.