Optical parametric generation in orientation-patterned gallium phosphide
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European Commission's projectMid-TECH - Infrared sensing made visible: Combining infrared light sources and upconversion sensors for improved sensitivity in medical applications and gas analysis (EC-H2020-642661)
We report an optical parametric generator (OPG) based on the new nonlinear material, orientation-patterned gallium phosphide (OP-GaP). Pumped by a 𝑄Q-switched nanosecond Nd:YAG laser at 1064 nm with 25 kHz pulse repetition rate, the OPG can be tuned across 1721–1850 nm in the signal and 2504–2787 nm in the idler. Using a 40-mm-long crystal in single-pass configuration, we have generated a total average output power of up to ∼18 mW∼18 mW, with ∼5 mW∼5 mW of idler power at 2670 nm, for 2 W of input pump power. The OPG exhibits a passive stability in total output power better than 0.87% rms over 1 h, at a crystal temperature of 120°C, compared to 0.14% rms for the input pump. The output signal pulses, recorded at 1769 nm, have duration of 5.9 ns for input pump pulses of 9 ns. Temperature-dependent loss measurements for the pump polarization along the  axis in the OP-GaP crystal have also been performed, for the first time, indicating a drop in transmission from 28.8% at 50°C to 19.4% at 160°C.
CitationYe, H. [et al.]. Optical parametric generation in orientation-patterned gallium phosphide. "Optics Letters", 15 Setembre 2017, vol. 42, núm. 18, p. 3694-3697.