In optical communications, the part of the infrared spectrum that is used is divided into seven bands based on availability of light sources transmitting/absorbing materials (fibers) and detectors:
O bandOriginal1260–1360 nm
E bandExtended1360–1460 nm
S bandShort wavelength1460–1530 nm
C bandConventional1530–1565 nm
L bandLong wavelength1565–1625 nm
U bandUltralong wavelength1625–1675 nm
The C-band is the dominant band for long-distance telecommunication networks.
The S and L bands are based on less well established technology, and are not as widely deployed.