Microbent optical fibers as evanescent wave sensors

S. Thomas Lee; K. Geetha; V. P. N. Nampoori; C. P. G. Vallabhan; Periasamy Radhakrishnan

doi:10.1117/1.1519243

1 December 2002 Microbent optical fibers as evanescent wave sensors

S. Thomas Lee, K. Geetha, V. P. N. Nampoori, C. P. G. Vallabhan, Periasamy Radhakrishnan

Optical Engineering, Vol. 41, Issue 12, (December 2002). https://doi.org/10.1117/1.1519243

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.

©(2002) Society of Photo-Optical Instrumentation Engineers (SPIE)

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S. Thomas Lee, K. Geetha, V. P. N. Nampoori, C. P. G. Vallabhan, and Periasamy Radhakrishnan "Microbent optical fibers as evanescent wave sensors," Optical Engineering 41(12), (1 December 2002). https://doi.org/10.1117/1.1519243

Published: 1 December 2002

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