A TPP-Fabricated Fiber Tip Fabry-Perot Hydrogen Sensor with a Scissor-Like Clamped Beam

Fabry-Perot interferometers (FPIs) fabricated on fiber tips by two-photon polymerization (TPP) have shown promising sensitivity for hydrogen sensing. However, conventional TPP-fabricated FPI hydrogen sensors typically employ a single-ended cantilever beam, whose one-sided fixation provides limited structural stability, making it inherently susceptible to environmental vibrations and gas-flow disturbances that may cause false alarms during practical hydrogen detection. To solve the problem, a double-ended clamped beam FPI is proposed for hydrogen sensing. To address the sensitivity degradation caused by the increased stiffness of the double-ended configuration, we systematically investigate the influence of scissor-like structural parameters including parallelogram hollow dimensions and row number-on the mechanical response of the clamped beam through finite element analysis, and propose a scissor-like clamped beam configuration featuring a single-row parallelogram hollows beam. The proposed sensor exhibits a high hydrogen sensitivity of 1.2 nm/%, a fast response time of 15.7 s, and strong robustness against flow-rate fluctuations, with a flow-rate dependence of only 0.84 pm/SCCM, representing a 3.25-fold reduction compared with a conventional cantilever beam structure. This work provides a compact all-optical platform for safe hydrogen leak detection and monitoring in harsh environments.