Fiber optic communications is dependent on the principle that light in a glass medium can carry more information over longer distances than electrical signals can carry in a copper or coaxial medium. The purity of today’s glass fiber mixed with advance electronics system allows fiber to transmit digitized light signals well beyond 100 km without amplification. Optical fiber is an ideal transmission medium with few transmission losses, low interference and high bandwidth potential.
How Fiber Works
The working of an optical fiber is dependent on the principle of total internal reflection. Light reflects or refracts based on the angle at which it strikes a surface. This principle is at the center of how optical fiber works. Restricting the angle at which the light waves are delivered makes it possible to control how efficiently they reach their destination. Light waves are covered with the core of the optical fiber in much the same way that radio frequency signals are covered with coaxial cable. The light waves are directed to the other end of the fiber by being reflected within the core.
The creation of the cladding glass relative to the core glass decides the fiber’s capability to reflect light. That reflection is usually occurred by creating a higher refractive index in the core of the glass than in the surrounding cladding glass creating a “waveguide”. The refractive index of the core is improved by slightly changing the composition of the core glass generally by adding small amounts of a dopant. Alternatively the waveguide can be composed by decreasing the refractive index of the cladding using different dopants.
Design of Fiber
Core, Cladding, and Coating
An optical fiber is made up of two different types of highly pure, solid glass composed to form the core and cladding. A protective coating surrounded with the cladding. In most cases the protective coating is a double layer composition.
In the manufacturing process, a protective coating is applied to the glass fiber as the final step. This coating protects the glass from scratches and dust that can affect fiber strength. This protective coating can be composed with two layers: a soft inner layer that act as cushions to the fiber and permits the coating to be uncovered from the glass mechanically and a harder outer layer that protects the fiber during handling particularly the cabling, installation, and termination processes.
Types of Fiber
There are two types of optical fiber: single-mode and multimode.
Single-Mode and Multimode Fibers
Multimode fiber was type to be used for commercial purpose. It is provided with larger core than single-mode fiber permitting hundreds of modes of light to propagate through the fiber simultaneously. Additionally the larger core diameter of multimode fiber makes possible the use of lower-cost optical transmitters or vertical cavity surface emitting lasers and connectors.
cooltechcrunch 