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Proceedings Paper

Interrogation of fiber Bragg grating sensors using dual-wavelength pulses generated from a self-seeded Fabry-Perot laser diode
Author(s): Yunqi Liu; Kin Seng Chiang; Pak Lim Chu
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Paper Abstract

We present a simple technique for the interrogation of fiber Bragg grating (FBG) sensors using a self-seeded Fabry-Perot laser diode (FP-LD). The FBG sensor is configured in such a way that its reflection spectrum consists of two peaks, whose separation depends on the physical parameter to be measured. When the modulating frequency of the FP-LD is set properly, stable short pulses at the two wavelengths selected from the same FP-LD mode with the FBG are generated simultaneously. The wavelength separation of the dual-wavelength pulses is converted into a time difference by transmitting the pulses through a dispersive fiber. In this way, accurate wavelength measurement is replaced by the less expensive time measurement. To multiplex similar sensors that are sufficiently far apart spectrally, it is only necessary to change the modulating frequency of the FP-LD. To balance the pulse intensities at the two wavelengths for a particular sensor, the temperature of the FP-LD can be adjusted. Using this technique, we demonstrated experimentally a number of FBG-based sensors, including displacement/bending sensors, temperature-compensated current sensors, and transverse force sensors. This technique provides an intensity-referencing-free demodulation scheme, an easy way to interrogate a series of sensors, and an effective means to overcome drifts.

Paper Details

Date Published: 14 February 2005
PDF: 12 pages
Proc. SPIE 5634, Advanced Sensor Systems and Applications II, (14 February 2005); doi: 10.1117/12.569395
Show Author Affiliations
Yunqi Liu, City Univ. of Hong Kong (Hong Kong China)
Kin Seng Chiang, City Univ. of Hong Kong (Hong Kong China)
Pak Lim Chu, City Univ. of Hong Kong (Hong Kong China)


Published in SPIE Proceedings Vol. 5634:
Advanced Sensor Systems and Applications II
Yun-Jiang Rao; Osuk Y. Kwon; Gang-Ding Peng, Editor(s)

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