Cladding (fiber optics)

[2] Improving transmission through fibers by applying a cladding was discovered in 1953 by Dutch scientist Bram van Heel.

[4] Early cladding materials included oils, waxes, and polymers.

Modern fibers have a primary polymer overcoat with a refractive index that is slightly higher than that of the cladding, so that light propagating in the cladding is rapidly attenuated and disappears after only a few centimeters of propagation.

An exception to this is double-clad fiber, which is designed to support a mode in its inner cladding, as well as one in its core.

The inclusion of a glass cladding greatly reduces the attenuation caused by these surface irregularities.

Additionally, the inclusion of a cladding layer also allows for the usage of smaller glass fiber cores.

[4] With most glass fibers have a cladding that raises the total outer diameter to 125 microns.

[7] The numerical aperture of a multimode optical fiber is a function of the indices of refraction of the cladding and the core: The numerical aperture allows for the calculation of the acceptance angle of incidence at the fiber interface.

[5] Which will give the maximum angle at which the incidence light can enter the core and maintain total internal reflection:

[7] Due to the relatively greater transmission of light they offer, fiber optic cores and claddings are usually made from highly purified silica glass.

Certain impurities can be added to impart various properties, such as increasing transmission distance or improving fiber flexibility.