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Optical Engineering

Fiber optic microampere dc current sensor
Author(s): Wuu Wen Lin; Shih-Chu Huang; Mao-Hsiung Chen
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Paper Abstract

A microampere dc current is measured by a fiber optic sensor. The phase change of the guided light induced by ohm's heat over a golden-coated fiber is detected by an interferometer. The thermal conduction of the optical fiber and the relation of the temperature-induced phase change of the guided light are explored. A Michelson interferometer plus a Faraday rotator mirror enable system immunity from the polarization-induced signal fading due to the environmental disturbance, especially by vibration and temperature. A passive phase-generated carrier (PGC) demodulation scheme enables the system to demodulate the interference signal stably by shifting the signal away from the high-noise, low-frequency band through a carrier. The sensitivity of the sensing system is improved by a biased method. The minimum measurable dc current is 3.416×10–7 A with a dynamic range of 89.33 dB.

Paper Details

Date Published: 1 September 2003
PDF: 7 pages
Opt. Eng. 42(9) doi: 10.1117/1.1597675
Published in: Optical Engineering Volume 42, Issue 9
Show Author Affiliations
Wuu Wen Lin, Yung Ta Institute of Technology & Commerce (Taiwan)
Shih-Chu Huang, Chung Shan Institute of Science and Technology (Taiwan)
Mao-Hsiung Chen, National Sun Yat-Sen Univ. (Taiwan)

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