Surface roughness effects on ENZ media IR spectra

The development of high-performance nanophotonic technologies faces challenges like material losses and surface roughness. While surface roughness has been studied in the plasmonic regime, its effect on epsilon-near-zero (ENZ) media has been less explored. Two theoretical scenarios arise regarding roughness in ENZ media: one predicts the excitation of a strong longitudinal electric field, while the other suggests minimal changes in reflection due to the large effective wavelength. This study investigates silicon carbide (SiC) as an ENZ substrate, using deep reactive ion etching (DRIE) to create significant surface roughness. The findings show that surface roughness affects the reflection spectra, induces polaritonic effects, and highlights the robustness of SiC against surface roughness. Numerical simulations and experimental measurements confirm these results, revealing that ENZ substrates maintain their reflective properties even with surface roughness on the scale of hundreds of nanometers.