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Optical Engineering

Microbent optical fibers as evanescent wave sensors
Author(s): S. Thomas Lee; K. Geetha; V. P. N. Nampoori; C. P. G. Vallabhan; Periasamy Radhakrishnan
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Paper Abstract

Microbent optical fibers are potential candidates for evanescent wave sensing. We investigate the behavior of a permanently microbent fiber optic sensor when it is immersed in an absorbing medium. Two distinct detection schemes, namely, bright-field and dark-field detection configuration, are employed for the measurements. The optical power propagating through the sensor is found to vary in a logarithmic fashion with the concentration of the absorbing species in the surrounding medium. We observe that the sensitivity of the setup is dependent on the bending amplitude and length of the microbend region for the bright-field detection scheme, while it is relatively independent of both for the dark-field detection configuration. This feature can be exploited in compact sensor designs where reduction of the sensing region length is possible without sacrificing sensitivity.

Paper Details

Date Published: 1 December 2002
PDF: 5 pages
Opt. Eng. 41(12) doi: 10.1117/1.1519243
Published in: Optical Engineering Volume 41, Issue 12
Show Author Affiliations
S. Thomas Lee, Cochin Univ. of Science and Technology (India)
K. Geetha, Cochin Univ. of Science and Technology (India)
V. P. N. Nampoori, Cochin Univ. of Science and Technology (India)
C. P. G. Vallabhan, Cochin Univ. of Science and Technology (India)
Periasamy Radhakrishnan, Cochin Univ. of Science and Technology (India)

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