Recalibration of the nonlinear optical coefficients of BaGa₄Se₇ crystal using second-harmonic-generation method

Nonlinear optical coefficients are important parameters for nonlinear optical crystals. Based on the previously disclosed BaGa₄Se₇ crystal coefficients, the optimum phase-matching direction with the largest effective nonlinear optical coefficient appears in the second octant (90^∘<θ<180^∘, 0^∘<ϕ<90^∘). In this study, a recalibration was performed using the second-harmonic-generation method, and it was confirmed that the optimum phase-matching direction of the BaGa₄Se₇ crystal is located in its XZ principal plane (ϕ=0^∘). Therefore, this study will serve as a good reference for future applications of this excellent crystal.