Optimization of Pd Surface Plasmon Resonance sensors for hydrogen detection

A design to optimize a fiber optic Surface Plasmon Resonance (SPR) sensor using Palladium as a sensitive layer for hydrogen detection is presented. In this approach, the sensitive layer is deposited on the core of a multimode fiber, after removing the optical cladding. The light is injected in the fiber with a given wavelength and all fiber modes are equally excited. The intensity modulation at the fiber output is measured to estimate the presence of hydrogen absorbed by the Pd, and consequently the Hydrogen concentration in the environment. The sensor response depends on both the Transverse Magnetic (TM) polarization (magnetic field perpendicular to incidence plane) and the Transverse Electric (TE) polarization (electric field perpendicular to incidence plane). The response for the Transverse Electric polarization is opposite with respect to the Transverse Magnetic polarization. The objective here is to optimize the Pd-SPR hydrogen sensor design in order to increase its sensitivity. We introduce an analysis of the sensor response as a function of the Pd thickness. Finally, a new design based on a multilayer system is proposed to enhance the SP ’effect’.