Infrared waves are used for optical transmission technology by means of optical waveguides, in infrared connections and infrared LANs. According to DIN 5031, the infrared range lies in the spectral range from 0.78 µm to 1 mm, which corresponds to a frequency range between 300 GHz and approx. 400 THz. The entire infrared spectrum is divided into several different spectral ranges.
The wavelength range between 0.78 µm and 3.0 µm is composed of several infrared regions. The NearInfrared( NIR), which ranges from 0.78 µm to 1.4 µm and is used for communications transmission in optical fibers, and the Short Wavelength Infrared( SWIR), which covers the wavelength range between 1.4 µm and 3.0 µm. Longer wavelengths, from 3.0 µm to 5.0 µm, are covered by Mid Wavelength Infrared (MWIR), also known as intermediate infrared. Long Wavelength Infrared (LWIR) has even longer wavelengths, ranging from 5.0 µm to 15 µm. FarInfrared( FIR) has the longest wavelengths, with wavelengths between 15 µm and 1 mm. In addition, there is thermal infrared, Thermal Infrared( TIR), which is generated by thermal radiation from human bodies and other heat sources and lies in several infrared wavelength ranges.
IR radiation is used in infrared sensors of alarm systems, but also in message transmission. The latter takes place in optical waveguides in the wavelength range from 650 nm to 1,600 nm.