Polarization-maintaining optical fiber
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2008-07-17T05:39:34Z
Srleffler
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In [[fiber optics]], '''polarization-maintaining optical fiber''' ('''PMF''' or '''PM fiber''') is [[optical fiber]] in which the [[polarization]] of [[linear polarization|linearly-polarized]] [[light wave]]s launched into the fiber is maintained during [[Wave propagation|propagation]], with little or no cross-coupling of optical [[Power (physics)|power]] between the polarization [[Normal mode|mode]]s. Maintaining polarization is important in modern [[telecommunication]] systems and in various other special applications of fiber optics.
Several different designs of PM fiber are used. Most work by inducing [[Stress (physics)|stress]] in the [[Fiber_optics#Principle_of_operation|core]] via a non-circular [[cladding]] [[Cross section (geometry)|cross-section]], or via rods of another material included within the cladding. Several different shapes of rod are used, and the resulting fiber is sold under brand names such as "Panda" and "Bow-tie". The differences in performance between these types of fiber are subtle. Some of the differences are explained in the article "[http://www.laserfocusworld.com/display_article/209825/12/none/none/OptWr/Panda-style-fibers-move-beyond-telecom PANDA-style fibers move beyond telecom]".<ref>{{cite journal |title=PANDA-style fibers move beyond telecom |journal=Laser Focus World |month=August |year=2004 |first=Adrian |last=Carter |coauthors=Samson, Bryce |url=http://www.laserfocusworld.com/display_article/209825/12/none/none/OptWr/Panda-style-fibers-move-beyond-telecom |accessdate=2008-07-17}}</ref>
Polarization-maintaining optical fibers are used in special applications, such as in fiber optic sensing, [[interferometry]] and [[quantum key distribution]]. They are also commonly used in telecommunications for the connection between a source [[laser]] and a [[modulator]], since the modulator requires polarized light as input. They are rarely used for long-distance transmission, because PM fiber is expensive and has higher [[Absorption (optics)|attenuation]] than [[singlemode fiber]].
==References==
*[[Federal Standard 1037C]]
*[[MIL-STD-2196]]
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==External links==
*[http://www.fujikura.co.jp/00/optde/pdf/16pnb04.pdf Fujikura's PANDA Fiber] Specs for the most common type of PM fiber
[[Category:Optical fiber]]