Optical fiber hydrogen sensor using metasurfaces composed of palladium

Palladium-based hydrogen sensors have been typically studied due to the dielectric function that changes with the hydrogen concentration. However, the development of a reliable, integral, and widely applicable hydrogen sensor requires a simple readout mechanism and an optimization of the fast detection of hydrogen. In this work, optical fiber hydrogen sensing platforms are developed using an optimized metasurface, which consists of a layer of palladium nanoantennas array suspended above a gold mirror layer. Since the optical properties of these palladium nanoantennas differ from the traditional palladium films, a high reflectance difference can be achieved when the sensor based on the metasurface is exposed to the hydrogen atmosphere. Finally, the optimized reflectance difference ΔR of ∼0.28 can be obtained when the sensor is exposed in the presence of hydrogen. It is demonstrated that this integrated system architecture with an optimized palladium-based metasurface and a simple optical fiber readout system provides a compact and light platform for hydrogen detection in various working environments.