Study of mid-IR laser generation based on BaGa4Se7 optical parametric oscillators

The phase matching and effective nonlinear coefficients in three planes of BaGa₄Se₇ (BGSe) crystal are simulated, and the optimal design of phase matching planes and matching types is given. At the same time, the cavity length and pump intensity threshold of the OPO are analysed, and the partial optimization design of the OPO is given. The experimental platform of optical parametric oscillator is designed and built. The idle pulse energy of 2980 nm is 0.806 mJ, 4132 nm is 0.263 mJ, and 6118 nm is 0.084 mJ. The corresponding optical-optical conversion efficiencies are 7.8%, 2.5% and 1%, and the slope efficiencies are 9%, 2.8% and 1.4%, respectively.