Germanium(Ge) is widely used in far infrared wavelength, it is transparent from 2 micron to 17 micron.. Germanium also has higher refractive index about 4 at 10.6 micron. Germanium is very popular in FLIR and imaging applications.

• Transmission Range: 2000 nm~17000 nm
• Thermal Expansion Coefficient: 5.5x10^-6/K
• Density: 5.33g/cm³