(a) What is the structure of an optical fiber?
(b) What is the principle used for transmitting audio and video signals using optical fiber? Explain the principle.
a) The basic structure of an optical fiber consists of three parts; the core, the cladding, and the coating or buffer. The basic structure of an optical fiber is shown in figure. b) Total internal reflection is the operating principle of optical fibers, which are used in endoscopes and telecommunications. An optical fiber consists of a very thin core of high purity glass. The core is covered by a second layer (cladding) also made from high purity glass. The cladding is less dense than the core and has a lower refractive index for total internal reflection to occur. Thus light rays passing along the core at an angle greater than the critical angle are totally internally reflected. The surface of the high purity glass core acts like a perfect mirror and the light ray is continuously reflected along the length of the optical fiber core.