Infrared temperature tunability in GaSe, HgS, and Tl3AsSe3nonlinear devices

Temperature coefficients of refractive indexes
dn/dt
determine temperature stability and temperature tuning in nonlinear optical laser devices. These coefficients for three infrared crystals HgS, GaSe, and Tl
3
AsSe
3
are analyzed for the first time to find refractive indexes at different temperatures to predict therefrom the tuning curves for some three-wave parametric interactions.