Zinc selenide (ZnSe) is a widely used material for optical components in the IR range. In contrast to other materials such as Ge or Si, zinc selenide is also transparent in the visible range. It has a transmission of around 70 % in the wavelength range between 0.6 µm and 20 µm. The material is easy to process, chemically inert and has a high resistance to thermal shock and environmental influences.

ZnSe is not a naturally occurring material and is grown using chemical vapor deposition (CVD).

Compared to zinc sulphide (ZnS), zinc selenide is softer and more susceptible to scratches. However, ZnSe has better absorption and refractive index homogeneity at a wavelength of 10.6 µm and is therefore used in 10.6 µm high-power lasers. The material is also used in the broad IR range for night vision devices as well as lenses, windows and prisms.

ZnSe must be processed with particular care, as the vapors produced when grinding and polishing the material are toxic.