Development of Fiber Bragg Grating Based Novel All-Optical Sensors for Structural Health Monitoring

Abstract

This thesis focuses on the development of novel, all-optical Fiber Bragg Grating (FBG)-based tilt and liquid level sensors, designed for structural health monitoring (SHM) applications. The primary aim is to realize highly sensitive, accurate, and temperature-insensitive sensors with tunable response characteristics. Initially, a temperature-insensitive, non-pendulum type FBG tilt sensor is proposed, offering tunable performance via variable loaded mass and eliminating thermal effects through wavelength separation modulation between two FBGs. The sensor achieves a sensitivity of 0.0300 nm/°, accuracy of ±0.033°, and angular resolution of 0.067°. An improved design enhances sensitivity to 0.0415 nm/°, accuracy to ±0.024°, and resolution to 0.012°, maintaining excellent reversibility and reliability. A third design further boosts sensitivity to 0.3198 nm/°, accuracy to ±0.0031°, and resolution to 0.0016°, while preserving design simplicity and experimental fidelity.