Fiber Bragg Grating Sensors with Enhanced Sensitivity for High-Precision Multi-Parameter Detection

Abstract: Exceptional points (EPs), intrinsic to non-Hermitian systems, exhibit singular spectral responses with extreme sensitivity to external perturbations, offering new opportunities for precision sensing. In this work, we investigate the sensing performance of Fiber Bragg Gratings (FBGs) engineered to operate near EPs through precise structural tuning. By aligning the reflection spectrum edges with the EP condition, significant sensitivity enhancement is achieved under a power interrogation scheme. The optimized sensors demonstrate sensitivities of $\sim$9.3 dBm/ $<sup>{\circ}$C for temperature and 0.5 dBm/$\mu\epsilon$ for axial strain, representing nearly an order-of-magnitude improvement over conventional FBG sensors. To address cross-sensitivity between temperature and strains, a sensitivity matrix-based approach is implemented, enabling accurate simultaneous detection of multiple perturbations. These results establish EP-engineered FBGs as a highly effective and versatile platform for high-precision, multi-parameter sensing, with broad applicability in telecommunications, structural health monitoring, aerospace systems, and environmental diagnostics.