WS2-Assisted Field Localization in a Disordered Plasmonic Waveguide for Enhanced Refractive Index Sensing

We numerically demonstrate a disordered plasmonic waveguide incorporating a WS2layer for refractive index sensing. The waveguide geometry is progressively modified from a uniform structure to periodic and chamfered protrusions and then to a disordered configuration. The spatial distribution of the electric field is analyzed using the inverse participation ratio, effective localization length, and spatial correlation length. The results show that geometrical disorder alone produces a limited change in field localization, whereas the addition of WS2 to the disordered structure leads to a pronounced increase in field confinement. For the final structure, the inverse participation ratio reaches 8.675 × 10-3 and the effective localization length decreases to 48.18 nm, compared with 1.073 × 10-3 and 389.5 nm, respectively, for the reference structure. The refractive index is varied from 1.33 to 1.40, and the resulting spectral shifts are used to evaluate the sensing performance. A maximum wavelength sensitivity of 592.4 nm/RIU is obtained, with a full width at half maximum of 65 nm and a figure of merit of 9.11RIU-1. These results demonstrate that combining geometrical disorder with WS2 can enhance plasmonic field localization and provide an effective wavelength-based approach for refractive index sensing.