Fibre optical couplers are used to both split and combine optical signals in optical fibres. As passive optical components, they are often used in data transmission.
The optical frequency multiplexing method, wavelength division multiplexing (WDM), splits the wavelengths in such a way that each spectral colour has its own transmission channel.
These components are used for fibre-optical data transmission in communication applications. Isolators allow light to pass through the fibre in only one direction; circulators are non-reciprocal elements.
Attenuators are used to reduce the power of signals when the receiver is near the sender or the signal being sent is too strong, either of which would result in the receiver being overloaded.
Free-beam shutters are used to quickly and completely block a laser with collimated beams in different applications.
Fibre-optic components are also being used more and more in the area of photonics, in particular in fibre lasers.