Fibre optics: The term fiber optics originated from “fiber- thread like structure” and “optics-light”. It means a thread like structure through which light will pass.

Principle: The principle of optical fiber is “total internal reflection”.

Do you know what is total internal reflection: In this phenomenon, light should pass from denser to rarer medium and angle of incidence should be more than the critical angle.

Then the question arises what should be rarer and denser medium in optical fibers?

Let us discuss the parts of a fiber:

An optical fiber has following parts:

1. Core- It is the innermost part of the fiber.

2. Clad- It is outer part of the fiber.

3. Jacket or Sheath- It is the outermost part of an optical fiber.

Figure: Fiber parts

Core acts as denser medium and cladding as rarer. Thus, light passes through the core after total internal reflection.

Another purpose of clad is to provide mechanical strength to the core.

The function of the sheath is to protect the fiber from external impurities or contaminants.