Updated Sellmeier equations for AgGaSe2 valid up to 18 micron

This paper presents refined Sellmeier equations for AgGaSe2 that provide a good reproduction of the phase-matching angles for optical parametric oscillation and difference-frequency generation processes in the 1.85–18 μm range thus far reported in the literature. In addition, these equations are found to reproduce the experimental results for second-harmonic and sum-frequency generation of CO2 laser radiation in the 1.7652–10.5910 μm range.