Authors: Arun katuwal, Masinde Masinde
Structure, Materials, Manufacturing
Optical Fiber Materials
Background
An Optical Fiber is a flexible, transparent fiber made of extruded glass(silica) or plastic which is slightly thicker than human hair. It is smililar to the light pipe that is used to transmit light between the two ends of the fiber.Optical Fiber is mainly used in Commuacation, power Transmission, sensors and a lot of other things.
Optical Fiber currently known as the fastest means for transfering data. But What exactly is used to make Optical Fiber. What are the materials used. And how are these manaufactured?
Structure
Fiber optics has three components Fiber Core, The Cladding and The insulating Jacket. The Fiber core is the Fiber cable that carries light Signals. The cladding is a material that surrounds the core. Like the core, the cladding also consists of glass or plastic materials but with different densities. And the insulating jacket acts as a sheath that doesnot reflect light.
Materials
The fundamentals for making optical fiber need materials which are transparent and can be drown into the fiber with the distinct core cladding structure that is uniform along the length of the fiber and will survive in the desired working environment. To make thin, uniform fiber the approach is to heat up a material until it softens into a very thick or viscous liquid and then stretch the thick fluid into the thin ligaments.Durability of the material is vital.The most common materials for years are silica based glass and certain plastics.
Silica must be doped to form either a high-index core or a low index cladding for an all-glass fiber. Flourine can reduce the index of Silica; Germanium can increase its index.
Manafacture of Optical Fibers
The core and the cladding of an optical fiber are made of highly purified silica glass (fused-Silica Fibers). An optical fiber is manufactured from silicon dioxide. There are two methods of Manafacturing. The first, The Crucible Method and another The Vapor Deposition Process. In Crucible method powdered silica is melted, produces fatter, multimode fibers suitable for short-distance transmission of many light wave signals.In The Vapor Deposition Process we create a solid cylinder of core and cladding material that is then heated and drawn into a thinner, single-mode fiber for long-distance communication.There are more three types of Vapor Deposition Techniques: Outer Vapor Phase Deposition, Vapor Phase Axial Deposition, and Modified Chemical Vapor Deposition (MCVD). MCVD process is the most common manufacturing technique used in current days. MCVD yields a low-loss fiber well-suited for long-distance cables.
Impurities are the main cause of attenuation in standard silica glasses. Synthetic fused silica is the base for the communacation fibers, it is very clear because impurities are reduced to a part per billion or less. All plastic fibers have attenauation much higher than silica fibers. They are used for image transmission or short distance communications.