附录
一、英语原文
Optical fiber
Abstract:
An optical fiber (or optical fiber) is a flexible, transparent fiber made of a pure glass (silica) not much thicker than a human hair. It functions as a waveguide, or “light pipe”[1], to transmit light between the two ends of the fiber.[2] The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-munications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms munication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to ic interference. Fibers are also used for illumination, and are wrapped in bundles so that they may be used to carry images, thus allowing viewing in confined spaces. Specially-designed fibers are used for a variety of other applications, including sensors and fiber lasers.
Optical fibers typically include a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. This causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a wider core diameter, and are used for short-munication links and for applications where high power must be transmitted. Single-mode fibers are used for munication links longer than 1,050 meters (3,440 ft).
Joining lengths of optical fiber is plex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together, either mechanically or by fusing them with heat. Special optical fiber connectors for removable connections are also available.
【keywords】 optical Fiber Multi-mode fiber Index of refraction
Total internal reflection abs
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