SPR-based optical fiber sensor for hydrogen detection using Pd thin films

Energy consumption has increased exponentially due to population growth leading to an increasing impact on natural resources. Green hydrogen (H2) offers a safer alternative to fossil fuels, making it a promising alternative for sustainable energy consumption. However, due to H₂'s flammability it is crucial to monitor its concentrations in the environment. Optical sensors have been developed to monitor H₂ concentrations in harsh environments with high sensitivity and remote measurement. In this work, a numerical study and experimental validation of an optical fiber sensor based on Surface Plasmon Resonance (SPR) for H₂ detection are presented. This sensor is composed of a multi-mode fiber with a SPR structure of a metal/dielectric/Pd, where the Pd acts as a sensitive layer. The plasmonic active materials studied are Ag and Au, while TiO₂ and SiO₂ are used as dielectrics, finding that the metal materials have more impact on the SPR band definition, while the dielectric layers have an impact on the band spectral position. The optimized configuration with 25nm/60nm/3nm of Au/TiO₂/Pd was experimentally developed, obtaining a wavelength shift of 19nm for 2kPa of H2, validating the numerical results, and confirming the possibility of using this type of system for H₂ detection.