Asymmetric hybrid double dielectric loaded plasmonic waveguides for sensing applications

In this paper we report on the design of Long-Range Surface Plasmon Polariton hybrid double dielectric loaded plasmonic waveguides suitable for sensing applications. We investigate the optical properties of these plasmonic waveguides, in terms of propagation lengths and effective refractive index, when they are immersed in different analytes. We show that high refractive index spacers can be optimized to compensate the asymmetry that is always present in biosensors due to the refractive index mismatch between the analyte and the substrate. This compensation permits the propagation of Long-Range Surface Plasmon Polariton modes that can be successfully exploited for sensing applications due to their weaker confinement and long propagation lengths. The sensing performance analysis of the plasmonic waveguides shows resolution of the order of 10−6–10−7, values comparable or better than those proposed by other plasmonic sensor configurations.