Fabrication and Demodulation for Sensitivity Enhanced Fiber Fabry-Pérot Sensor Based on Hookean Effect

Fabry-Pérot interference (FPI) structure for strain measurement relies on complex and expensive air microcavities, significantly limiting its use in microstrain size. This article proposes a novel Hookean effect-based FPI sensor with polydimethylsiloxane (PDMS) flexible material as the cavity and ultrahard, completely opaque silicon carbide (SiC) crystal as the reflective surface, dubbed Hookean-type FPI sensor. The relationship between the axial strain response and the PDMS material properties is investigated to disclose the optimal cavity elastic material alternative. The proposed Hookean-type FPI sensor has an excellent linear response, with a sensitivity of up to ${15} \text {pm}/\mu \epsilon $ . To improve the demodulation efficiency and cost of microstrain sensors, a high-efficiency intelligent demodulation system based on the array waveguide grating (AWG) and back-propagation neural network (BPNN) for the Hooke-type FPI sensor is introduced to interrogate the axial microstrain along the fiber. Experiments conducted in the real-world axial strain dataset demonstrate the effectiveness and superiority of the proposed demodulation system. The proposed sensing framework can provide reliable analytical support for engineering applications.