Design of a compact and highly sensitive modal interferometer using hybrid modes of a dielectric loaded plasmonic waveguide

We show the presence of hybridization between fundamental TE and first higher-order TM modes in a dielectric loaded plasmonic waveguide of appropriately chosen core dimensions. Furthermore, a critical hybridization point is achieved at which both modes have nearly equal fraction of the TE and TM polarizations. Exploiting the interference among such modes, we propose the design of a compact and highly sensitive modal interferometer. The bulk and surface sensitivities of the proposed sensor are found to be ∼ 3 − 10 µ m / R I U for refractive index (RI) ∼ 1.33 − 1.36 and ∼ 0.7 n m / n m for an adsorbed layer of RI 1.45, respectively. The proposed sensor gives robust performance against fabrication imperfections and is stable against temperature fluctuations due to extremely low temperature cross-sensitivity ( ∼ 10 − 15 p m / ∘ C for a temperature change up to ∼ 100 ∘ C ).