Studying the effect of strain induced birefringence on the sensitivity of FBG sensors for Guided wave measurements

Rohan Soman*, Luigi Fazzi, Ali Nokhbatolfoghahai, Roger M. Groves, Wieslaw Ostachowicz

*Corresponding author for this work

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

Abstract

To perform active structural health monitoring (SHM), guided waves (GW) have received great interest as they can inspect large areas with a few sensors and are sensitive to barely-visible structural damages. Fiber Bragg grating (FBG) sensors offer several advantages such as small size, low weight and ability to be embedded but their use has been limited for GW sensing due to their limited sensitivity while using spectrometers. FBG sensors in the edge-filtering configuration have overcome this issue with reasonable sensitivity and there is a renewed interest in their use. It is well known that when subjected to a transverse strain, the circular cross-section of the fiber deforms into an elliptical shape generating the birefringence phenomenon. This deformation, influences the coupling mode of the light inside the FBG and hence, modifies the resulting reflectivity spectrum. This paper investigates how controlled changes in the reflectivity spectrum can be introduced using different transverse loads. The effect of the modified spectrum on the sensitivity of the FBG for GW measurements is then studied. The study also investigates the effect of the transverse strain on the coupling of the GW from the structure into the fiber.

Original languageEnglish
Title of host publicationHealth Monitoring of Structural and Biological Systems XVI
EditorsPaul Fromme, Zhongqing Su
PublisherSPIE
Number of pages10
ISBN (Electronic)9781510649712
DOIs
Publication statusPublished - 2022
EventHealth Monitoring of Structural and Biological Systems XVI 2022 - Virtual, Online
Duration: 4 Apr 202210 Apr 2022

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume12048
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X

Conference

ConferenceHealth Monitoring of Structural and Biological Systems XVI 2022
CityVirtual, Online
Period4/04/2210/04/22

Keywords

  • fiber Bragg grating birefringence
  • fiber optic sensors
  • guided waves
  • plate
  • sensitivity

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