What Is Optical Fiber?

We know that optical fibre has revolutionised the communication sector and made efficient data transmission possible. It consumes less power and is non-flammable. In this article, let us learn about optical fibre, types of optical fibre, working of optical fibre and its advantages in detail.

Table of Contents:

What Is an Optical Fibre?

Optical fibre is the technology associated with data transmission using light pulses travelling along with a long fibre which is usually made of plastic or glass. Metal wires are preferred for transmission in optical fibre communication as signals travel with fewer damages. Optical fibres are also unaffected by electromagnetic interference. The fibre optical cable uses the application of total internal reflection of light. The fibres are designed such that they facilitate the propagation of light along with the optical fibre depending on the requirement of power and distance of transmission. Single-mode fibre is used for long-distance transmission, while multimode fibre is used for shorter distances. The outer cladding of these fibres needs better protection than metal wires.

Types of Optical Fibres

The types of optical fibres depend on theย refractive index, materials used, and mode of propagation of light.

The classification based on the refractive index is as follows:

  • Step Index Fibres:ย It consists of a core surrounded by the cladding, which has a single uniform index of refraction.
  • Graded Index Fibres:ย The refractive index of the optical fibre decreases as the radial distance from the fibre axis increases.

The classification based on the materials used is as follows:

  • Plastic Optical Fibres:ย The polymethylmethacrylate is used as a core material for the transmission of light.
  • Glass Fibres:ย It consists of extremely fine glass fibres.

The classification based on the mode of propagation of light is as follows:

  • Single-Mode Fibres:ย These fibres are used for long-distance transmission of signals.
  • Multimode Fibres:ย These fibres are used for short-distance transmission of signals.

The mode of propagation and refractive index of the core is used to form four combination types of optic fibres as follows:

  • Step index-single mode fibres
  • Graded index-Single mode fibres
  • Step index-Multimode fibres
  • Graded index-Multimode fibres

Watch the video and learn more about total internal reflection

How Does an Optical Fibre Work?

The optical fibre works on the principle of total internal reflection. Light rays can be used to transmit a huge amount of data, but there is a problem here โ€“ the light rays travel in straight lines. So unless we have a long straight wire without any bends at all, harnessing this advantage will be very tedious. Instead, the optical cables are designed such that they bend all the light rays inwards (using TIR). Light rays travel continuously, bouncing off the optical fibre walls and transmitting end to end data. Although light signals degrade over progressing distances, depending on the purity of the material used, the loss is much less than using metal cables. A Fibre Optic Relay System consists of the following components:

  • The Transmitter โ€“ It produces the light signals and encodes them to fit to transmit.
  • The Optical Fibre โ€“ The medium for transmitting the light pulse (signal).
  • The Optical Receiver โ€“ It receives the transmitted light pulse (signal) and decodes them to be fit to use.
  • The Optical Regenerator โ€“ Necessary for long-distance data transmission.

Advantages of Optical Fibre Communication

  • Economical and cost-effective
  • Thin and non-flammable
  • Less power consumption
  • Less signal degradation
  • Flexible and lightweight

Frequently Asked Questions โ€“ FAQs


What is used for the fabrication of optical fibres that are used for communication?

Silica or multi-component glass are used for the fabrication of optical fibres.


Why is silica used for the fabrication of the optical fibres?

Silica has a perfect elasticity until it reaches the breaking point, which makes it best for fabrication.


What is the principle of fibre optical communication?

Total internal reflection is the principle on which the optical fibre communication is based.


Name the factors that are responsible for generating attenuation of optical power in fibre.

Following are the factors that are responsible for generating attenuation of optical power in fibre:

  • Absorption
  • Scattering
  • Waveguide effect

Why are plastic-clad silica fibre optic cables not user-friendly?

Following are the reasons why plastic-clad silica fibre optic cables not user-friendly:

  • The fibres are insoluble in organic solvents
  • Bonding becomes difficult
  • Connector application becomes difficult as there is excessive plasticity in the cladding

What is the Raman effect?

The Raman effect is the change in the wavelength of light which occurs when the molecules deflect the light beam.


What are the benefits of optical fibre cable?

Following are the benefits of optical fibre cable:

  • The data security is excellent
  • It is cost-effective
  • It wonโ€™t be affected by interference

What is the bandwidth of optical fibre?

900 THz is the bandwidth of the optical fibre.


What is core in the optical fibre?

The core is the inner part of the optical fibre, which carries light.


List a few advantages of optical fibre communication.

A few advantages of optical fibre communication are:

  • Less signal degradation
  • Thin and non-flammable
  • Economical and cost-effective
  • Less power consumption

Learn more about optics, fibre optics, its application and about multimode fibres from our expert tutors at BYJUโ€™S.

Test your Knowledge on what is optical fiber


Leave a Comment

Your Mobile number and Email id will not be published.



  1. Your material was helpful, thanks