Single-mode optical fiber 41716 222196780 2008-06-28T01:07:24Z CosineKitty 1750493 [[:en:User:NicoV/Wikipedia Cleaner/Documentation|WikiCleaner]] 0.76 - Repairing link to disambiguation page - [[Wikipedia:Disambiguation pages with links|You can help!]] In [[fiber-optic communication]], a '''single-mode optical fiber''' ('''SMF''') is an [[optical fiber]] designed to carry only a single [[ray (optics)|ray of light]] (mode). This ray of light often contains a variety of different [[wavelength]]s. Although the ray travels parallel to the length of the fiber, it is often called the [[transverse mode]] since its electromagnetic vibrations occur perpendicular (transverse) to the length of the fiber. Single-mode optical fibers are also called '''monomode optical fibers''', '''single-mode optical waveguides''', or '''unimode fibers'''. Unlike [[multi-mode optical fiber]]s, single mode fibers do not exhibit [[dispersion]] resulting from multiple spatial modes. Single mode fibers are also better at retaining the fidelity of each light pulse over long distances than are multi-mode fibers. For these reasons, single-mode fibers can have a higher [[Bandwidth (computing)|bandwidth]] than multi-mode fibers. Equipment for single mode fiber is more expensive than equipment for multi-mode optical fiber, but the single mode fiber itself is usually cheaper in bulk. A typical single mode optical fiber has a core diameter between 8 and 10 [[µm]]<ref name="arcelect">{{cite web | title = Fiber Optic Cable Tutorial | url = http://www.arcelect.com/fibercable.htm | author = ARC Electronics | date=2007-10-01 }}</ref> and a cladding diameter of 125 µm; the wavelength of the light is 1310 or 1550 [[nanometer|nm]].<ref name="arcelect" /> There are a number of special types of single-mode optical fiber which have been chemically or physically altered to give special properties, such as [[dispersion-shifted fiber]] and [[nonzero dispersion-shifted fiber]]. Data rates are limited by [[polarization mode dispersion]] and [[chromatic dispersion]]. In 2005, data rates of up to 10 gigabits per second were possible at distances of over 60 km with commercially available transceivers ([[Xenpak]]). The lowest order bound mode is ascertained for the wavelength of interest by solving [[Maxwell's equations]] for the boundary conditions imposed by the fiber, e.g., [[Fiber_optics#Principle_of_operation|core]] (spot) size and the refractive indices of the core and [[cladding]]. The solution of Maxwell's equations for the lowest order bound mode will permit a pair of orthogonally polarized fields in the fiber, and this is the usual case in a [[telecommunications|communication]] fiber. In step-index guides, single-mode operation occurs when the [[normalized frequency]], ''V'', is less than 2.405. For [[Power (physics)|power]]-law profiles, single-mode operation occurs for a normalized frequency, ''V'', less than approximately <math>2.405 \sqrt{\frac{g + 2}{g}}</math>, where ''g'' is the profile parameter. In practice, the orthogonal polarizations may not be associated with degenerate modes. ==See also== * [[Optical waveguide]] * [[Multi-mode optical fiber]] ==Notes== <references /> ==References== * [[Federal Standard 1037C]] * {{cite web | url = http://www.fiber-optics.info/articles/fiber-types.htm | title = Types of Optical Fiber | author = Force, Inc. | date=2005-14-14}} [[Category:Optical fiber]] ==External links== *[http://www.arcelect.com/fibercable.htm The Basics of Fiber Optic Cable] [[de:Singlemode-Faser]] [[no:Single-modus fiber]] [[sv:Singelmode]] [[zh:單模光纖]]