Editorial Feature

What is a Fiber Optic Coupler?

A fiber optic coupler may be described as an optical element that is used in fiber optic systems that have one or more input fibers and several output fibers. A coupler basically brings together two or more fibers cores to interact with each other. The basic coupler is the 2x2 coupler, which is made from fused fiber.

Couplers that are sensitive to certain wavelengths are used as multiplexers. The output from a fiber depends on the wavelength of light and the polarization that occurs. The refractive index of the fiber also plays an important role in the output. This datasheet will elaborate on the working, construction and application of optical couplers.

Working Principle

Fiber optic cables work based on total internal reflection of light. The refractive index and the angle of refraction are important parameters to be noted. When two or more fiber optic cables are fused together, the light from the core leaks onto the cladding of the other core in proximity. This leaked light can leak into the second core, this process is cyclic and light gets transferred over a certain length.

Construction and Types of Couplers

Fiber optic couplers can be made by fusing fibers together. Based on the type of inputs and outputs, couplers are categorized as star couples (multiple input and output) and tees (single input, two outputs).


Some of the applications of fiber optic couplers are as below:

  • Wavelength-division multiplexing
  • Telecommunications
  • High sensitivity interferometers.

Sources and Further Reading


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