Optics 101

What is an Optical Fiber Isolator?

Optical isolators are optical elements which allow light to propagate in only one direction.

An Introduction to Optical Isolators 

The propagation of light in one single direction is required in order to prevent optical back scattering or feedback which often leads to noise in many applications.

Fiber optic isolators operate based on a magneto-optical phenomenon known as the Faraday Effect.

Optical fiber isolators are also known as Faraday isolators and they play an important role in optical communication networks and laser systems.

Fiber optic isolators consist of a Faraday rotator and two polarizers.

Image Credit: nikkytok / Shutterstock.com

Working Principle of Optical Isolators

The incident light is linearly polarized by the first polarizer, before it falls on the rotator and is rotated by 45°.

The light then falls on the second polarizer which is aligned at 45° to the first polarizer. Due to Faraday Effect, the propagation of light in a backward direction is blocked.

The optical fibers are made of silicate glass which is doped with terbium in order to attain the maximum efficiency possible.

Applications of Optical Isolators 

Some of the applications of the optical fiber isolator include:

  • High power fibers
  • Optical communication networks
  • Telecommunications

References and Further Reading 


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