ptical Properties And Applications Of Germanium In Photonics

Two windows of atmospheric transparency in the infrared (IR) region of 3–5 μm and 8–14 μm almost overlap with the region of maximum transmission of germanium (Ge). Ge is transparent in the 1.8–23 μm range (although a number of phonon absorption bands are present in the 11–23 μm region), there is also a transparency window in the terahertz (THz) spectral range (~ 100–300 μm). Due to its physicochemical properties, crystalline germanium is one of the backbone materials of IR photonics and its use amounts to 25–30% of the total consumption pattern of this material.