Optimized design of a nanocomposite Ta₂O₅ and Pd multilayer OFSPR H₂ sensor: a theoretical analysis

For the first time, we perform a theoretical investigation into the operation of a multilayer nanocomposite based optical fibre surface plasmon resonance hydrogen sensor. The sensor consists of Pd nanoparticles embedded in host material of Ta2O5 over a thin continuous film of Ag, in place of a small unclad section of the fibre core. We compare the operation of this device to a sensor employing an individual multilayer based sensing stack (Ag/Ta2O5/Pd) by measuring the normalised output power through the fibre, and the sensor sensitivity. A much smaller modulation layer thickness is required in the NC structure in order to achieve the same spectral shift of the resonance location as compared to the IM based structure, thus indicating a faster response time. In both sensor types, sensitivity increased to a maximum with increasing modulation material thickness, beyond which it began to fall off. The NC based structure operated with overall higher sensitivity than the IM structure.