Phase-matching directions and refined Sellmeier equations of the monoclinic acentric crystal BaGa_4Se_7

Abstract

We directly measured the phase-matching directions of second-harmonic and difference frequency generation in the principal planes of the biaxial BaGa₄Se₇ (BGSe) crystal using the sphere method. The simultaneous fit of the data allowed us to refine the Sellmeier equations of the three principal refractive indices of BGSe, and to calculate the tuning curves for infrared optical parametric generation.