A two-wave mixing interferometer for phase and wavelength demodulation of fiber-optic ultrasound sensors

Yi Zhou*, Yi Qiao, Sridhar Krishnaswamy

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

A two-wave mixing (TWM) interferometer using InP:Fe in the C-band wavelength at 1550nm is demonstrated. The system can be used as a conventional phase-demodulator for laser ultrasonic applications. In addition, a wavelength demodulation configuration of the TWM interferometer is proposed for use with Fiber Bragg-Grating (FBG) ultrasound sensors. In this configuration, the FBG is illuminated with a broadband source, and any strain in the FBG is encoded as a wavelength change of the light reflected by the FBG. The reflected light from the FBG is spilt into two unbalanced paths and both beams (pump and signal) are mixed in the TWM system. A small wavelength change in the FBG reflected light can be thought of as an equivalent phase change between the pump and signal beams as they travel unbalanced path lengths. FBG demodulation using TWM enables selective monitoring of dynamic strains induced by ultrasound and acoustic emissions, even in the presence of large quasi-static strains that otherwise would cause the FBG sensor to drift. Since TWM interferometers can be readily multiplexed, the proposed technique can be used to demodulate signals from a network of FBG ultrasound (acoustic emission) sensors for use in structural health monitoring.

Original languageEnglish (US)
Title of host publicationReview of Progress in Quantitative Nondestructive Evaluation Volume 24
Pages1630-1637
Number of pages8
Volume760
DOIs
StatePublished - Apr 9 2005
EventReview of Progress in Quantitative Nondestructive Evaluation - Golden, CO, United States
Duration: Jul 25 2004Jul 30 2004

Other

OtherReview of Progress in Quantitative Nondestructive Evaluation
CountryUnited States
CityGolden, CO
Period7/25/047/30/04

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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