Silicon is commonly used as substrate material for far infrared transmission, the strong absorption band at 9 microns makes it unsuitable for CO2 laser transmission applications, but it is frequently used for laser mirrors because of its high thermal conductivity and low density, Silicon is also useful as a transmitter in the 20 micron range.
Applications: Optical windows, lens, filters materials in the 3 to 5 micron band Raw material of manufacturing semiconductor silicon devices for making high power rectifier, High power transistor, diode switch devices, etc.