A 10 kHz non-critical phase-matching 9.3–10.1 μm optical parametric oscillator based on BaGa₄Se₇ crystal

A 10 kHz non-critical phase matching (NCPM) optical parametric oscillator based on BaGa₄Se₇ crystal is demonstrated. By utilizing a dual-crystal cascade configuration, an average output power of 0.96 W at a wavelength of 9387 nm is achieved, with a slope efficiency of 5.73 %. In addition, the temperature-dependent wavelength-tuning characteristics of the BGSe crystal are systematically investigated. By decreasing the crystal temperature from 38 °C to 6 °C, an idler wavelength tuning range of 9387–10107 nm is achieved, corresponding to a central wavelength shift of 720 nm (22.5 nm/°C) and a linewidth variation of 40–60 nm. This study has unveiled the great potential of BGSe crystal in high power, high repetition rate long-wave infrared pulse generation.