Design Optimization of a Sensitivity-Enhanced Tilt Sensor Based on Femtosecond Fiber Bragg Grating

This study presents a sensitivity-enhanced tilt sensor based on femtosecond fiber Bragg gratings (FBGs). The sensor design follows static mechanics principles, where strain increases when displaced from the neutral axis. The novel use of femtosecond FBGs further enhances the sensor’s sensitivity and reliability compared to conventional FBGs. Finite element analysis (FEA) identified the optimal distance of 4.4 mm for maximum strain. A prototype sensor was manufactured and tested within a tilt range of -30° to 30°. Experimental results show an improved sensitivity of 129.95 pm/° and linearity of 0.9997. The sensor demonstrated repeatability (error < 0.94%), creep resistance (error < 0.30%), and temperature stability (error < 0.90%). Deployed in an underground pipeline project, it successfully monitored tilt highlighting its potential for structural health monitoring (SHM).