Gallium selenide is a nonlinear optical material and photoconductor and it is mainly used for such applications as second harmonic generation of CO₂-lasers, up-conversion of CO₂-laser radiation image into near-IR or visible region, frequencies mixing in the middle IR region, differential frequencies generation (DFG) in the middle IR region from 5.5 to 18.0 μm

Basic properties

Structure 62m; a = 3.74 ; c = 15.89

Density    5.03 g/cm3

Mohs hardness        2

Eg, eV       2.02

Refractive indices at 5.3 μm   no = 2.8340; ne = 2.4599

Refractive indices at 10.6 μm no = 2.8136; ne = 2.4389

Refractive index at 0.633 μm  no= 2.9365