Index-matching material: Difference between revisions

Revision as of 01:39, 20 February 2003

Revision as of 05:27, 5 March 2005

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''Note 1:'' An index-matching material may be used in conjunction with pairs of mated connectors, with mechanical splices, or at the ends of fibers.

''Note 2:'' Without the use of an index-matching material, Fresnel reflections will occur at the smooth endfaces of a fiber. These reflections may be as high as -14 [[Bel|dB]] (''i.e.,'' 14 dB below the level of the incident [[signal]]). When the reflected signal returns to the transmitting end, it is reflected again and returns to the receiving end at a level that is (28 plus twice the fiber [[loss]]) dB below the direct signal. The reflected signal will also be delayed by twice the [[delay]] [[time]] introduced by the fiber. The reflected [[signal]] will have no practical effect on [[digital]] systems because of its low level relative to the direct signal; ''i.e.'' , it will have no practical effect on the detected signal seen at the decision point of the digital [[optical receiver]]. It may be noticeable in an analog [[baseband]] [[intensity]]-modulated [[video]] signal.

Source: from [[Federal Standard 1037C]]