1 March 2018

Graded index fiber

Definition of Graded-index fiber :

An optical fiber with a core having a refractive index that decreases with increases radial distance from the fiber axis. The most common refractive index for a graded index fiber is very nearly parabolic. The parabolic result in continual refocusing of the rays in the core, and compensates for multimode distortion.

The graded index fiber has a core is made from many layers of glass. In the graded index fiber the refractive index is not uniform within the core, it is highest at the center and decreases smoothly and continuously with distance towards the cladding side. The refractive index profile across the core that takes place in the look like parabolic nature.

In graded-index fiber, the light waves are bent by refraction towards the core axis and they follow the curved path down the fiber length side. This result because of change in refractive index as moved away from the center of the core side.
Graded index fiber 

Multimode graded-index fiber :

The core size of multimode graded index fiber cable is varying from 50 to 100-micrometer range. 

In this fiber, the light ray enters the fiber at many different angles. So in graded index fiber, the light propagates across the core toward the center it is intersecting a less dense to more dense medium. This article gives some advantages of graded index fiber to know more details about it 

Therefore the light rays are being constantly being refracted and the ray is bending continuously. This cable is mostly used for long distance communication system.

Multimode graded index fiber

Some important point of graded index fiber :
  • Graded index fiber data rate is very high.
  • The path of light is helical in manner.
  • Graded index fiber is of only one types that is a multimode fiber.
  • Coupling efficiency is low.
  • In graded-index fiber, the diameter of the core is about 50 micrometer in the case of multimode fiber.
  • Attenuation is less.
  • Refractive index is non-uniform.
  • Graded index the bandwidth is high.  
  • It is mostly used in local and wide area networks.