PMC

(a) Plot showing the normalized change in the waveguide mode index (Δn/n) as a function of roughness size for dielectric (Si, w = 500 nm, t = 220 nm) and plasmonic slot waveguides (Au, t = 100 nm, w = 75 nm) at 650 nm. The roughness in these calculations is modeled by a single spherical particle at the center of the waveguide mode as shown in the field plots in (b,c). The unperturbed mode index is used to normalize the change in the two cases. As can be seen, the plasmonic slot waveguide is far more sensitive to surface roughness as compared to the dielectric waveguide.

a, b Transfer matrix calculations for the MoS₂/SiO₂/Si system for MoS₂ anisotropic and isotropic (in the assumption of optical constants for the c-axis equal to those for the ab-plane) models. The experimental (q = 1/λ, E = h∙c/λ) data points (green triangles) show good agreement with the calculated dispersion (blue lines) based on the anisotropic dielectric function from Fig. . The inset is a magnified near-infrared spectral range with a white dashed line illustrating the isotropic case’s dispersion relation. The error bars show the uncertainty in the determination of mode in-plane momenta q from near-field images displayed in Fig. .

The multilayers are composed of dielectric and negative-permittivity materials.

Schematics of the manufacturing process of a porous waveguide/nanoarray electrode. a A high refractive index glass slide is coated with a Au layer using a thin Ti layer for improved adhesion. On top of the Au layer, a dielectric film of desired thickness and refractive index is deposited. A disperse layer of polystyrene nanoparticles is self-assembled on top of the dielectric film. The mean spacing of the particles is set by a combination of exposure time and ionic strength of the solution. b Optional step for shrinking the particles using UV/ozone etching (UVO) of the polystyrene. c A 10–20-nm-thick layer of Cr is deposited. d The particles are removed mechanically using tape stripping. e Reactive ion etching (RIE) with a high anisotropic etching rate for the dielectric layer and a negligible etching rate for Au and Cr is used to etch through the dielectric film at the exposed holes in the Cr mask. f The Cr mask is removed by wet etching