High energy mid-infrared laser pulse output from a BaGa₄Se₇ crystal-based optical parametric oscillator

We report a high energy, narrow spectral linewidth mid-infrared laser pulse output from a Nd:Y₃Al₅O₁₂ laser-pumped BaGa₄Se₇ (BGSe) crystal-based optical parametric oscillator (OPO). Output pulse energy of 21.5 mJ was obtained at 3816 nm, with spectral width of 12 nm and pulse width of 11.4 ns, corresponding to peak power as high as 1.89 MW. A BGSe crystal with aperture size of 10mm×10mm and length of 16 mm was applied as the nonlinear crystal in a pump fed back OPO for achieving such high pulse energy output from the simple oscillator scheme.