Multi-resonance enhanced photothermal synergistic fiber-optic Tamm plasmon polariton tip for high-sensitivity and rapid hydrogen detection

Accurate and real-time detection of hydrogen (H₂) is essential for ensuring energy security. Fiber-optic H₂ sensors are gaining attention for their integration and remote sensing capabilities. However, they face challenges, including complex fabrication processes and limited response times. Here, we propose a fiber-optic H₂ sensing tip based on Tamm plasmon polariton (TPP) resonance, consisting of a multilayer metal/dielectric Bragg reflector deposited directly on the fiber end facet, simplifying the fabrication process. The fiber-optic TPP (FOTPP) tip exhibits both TPP and multiple Fabry-Perot (FP) resonances simultaneously, with the TPP employed for highly sensitive H₂ detection. Compared to FP resonance, TPP exhibits more than twice the sensitivity under the same structural dimension without cavity geometry deformation. The excellent performance is attributed to alterations in phase-matching conditions, driven by changes in penetration depth of TPP. Furthermore, the FP mode is utilized to achieve an efficient photothermal effect to catalyze the reaction between H₂ and the FOTPP structure. Consequently, the response and recovery speeds of the FOTPP tip under resonance-enhanced photothermal assistance are improved by 6.5 and 2.1 times, respectively. Our work offers a novel strategy for developing TPP-integrated fiber-optic tips, refines the theoretical framework of photothermal-assisted detection systems, and provides clear experimental evidence.