Surface Plasmon Resonance Hydrogen Sensor based on Hetero-core Optical Fiber Structure

In this paper, we report the surface plasmon resonance (SPR) hydrogen sensor based on hetero-core optical fiber structure. This sensor consists of a multilayer stack made of a gold, a tantalum pentaoxide and a palladium (Pd) layer. It have been known that permittivity of Pd, which is a hydrogen storage metal, slightly changes with Pd hydrogenation. We experimentally obtained that SPR resonance was changed by 28 nm in wavelength with ranging from 0 to 4% hydrogen concentration. In addition, it was found that Pd thickness could tune the SPR resonance wavelength. On the other hand, its SPR broad spectrum enables the proposed sensor to be modulated with intensity-basis with an LED operation at 850 nm. It was presented that the proposed sensor induced a transmitted loss change of approximately 0.4 dB with reaction time of 40 sec. in the range of 0 – 4% hydrogen.