Dual parameter calibration of fiber Bragg grating system for simultaneous measurement

Abstract

This paper presents a numerical study of a dual-parameter fiber Bragg grating (FBG) sensing system for simultaneous measurement of temperature and strain with effective cross-sensitivity mitigation. The proposed system employs two FBGs operating at distinct Bragg wavelengths of 1550 nm and 1555 nm and subjected to different mechanical boundary conditions. One FBG is mounted in a loose-tube configuration to provide temperature-only sensitivity, while the second FBG is bonded to an elastic substrate, enabling simultaneous sensitivity to temperature and strain. Grating structures are designed using OptiGrating, and the optical interrogation system is modeled in OptiSystem. Calibration procedures, sensitivity matrix formulation, and decompensation algorithms are implemented numerically in MATLAB. Temperature calibration is performed over a range of 20°C – 80°C, while strain calibration is conducted from 0 to 2000 microstrain. The simulation results demonstrate highly linear responses, yielding sensitivity coefficients of 10.209 pm/°C for temperature and 1.2020 pm/ microstrain for strain, with coefficients of determination exceeding 0.997. The proposed decompensation algorithm successfully suppresses temperature-induced strain errors, reducing uncompensated crosssensitivity from 229.43 microstrain to numerically negligible levels under ideal simulation conditions. These results indicate that the proposed dual-parameter FBG sensing system offers high accuracy, stability, and immunity to electromagnetic interference, making it suitable for high-precision structural and industrial monitoring applications.