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

Rohan Soman; Luigi Fazzi; Ali Nokhbatolfoghahai; Roger Groves; Wieslaw Ostachowicz

doi:10.1117/12.2612487

19 April 2022 Studying the effect of strain induced birefringence on the sensitivity of FBG sensors for guided wave measurements

Rohan Soman, Luigi Fazzi, Ali Nokhbatolfoghahai, Roger Groves, Wieslaw Ostachowicz

Author Affiliations +

Proceedings Volume 12048, Health Monitoring of Structural and Biological Systems XVI; 1204807 (2022) https://doi.org/10.1117/12.2612487
Event: SPIE Smart Structures + Nondestructive Evaluation, 2022, Long Beach, California, United States

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.

Conference Presentation

Citation Download Citation

Rohan Soman, Luigi Fazzi, Ali Nokhbatolfoghahai, Roger Groves, and Wieslaw Ostachowicz "Studying the effect of strain induced birefringence on the sensitivity of FBG sensors for guided wave measurements", Proc. SPIE 12048, Health Monitoring of Structural and Biological Systems XVI, 1204807 (19 April 2022); https://doi.org/10.1117/12.2612487

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