Transmission‐Mode Silicon‐Rich Nitride Mie‐Void Metasurfaces in the Visible

Abstract

Mie‐void metasurfaces have so far been developed mainly in reflection, where subwavelength voids embedded in high‐index media support localized resonances and spectrally selective optical responses. Here we introduce Mie‐void metasurfaces operating in transmission, implemented using the silicon‐rich nitride (SRN) platform for visible‐range operation. We show that this transition is not a simple change in geometry: placing the voids in a finite film on a substrate introduces slab‐guided and Fabry–Pérot‐like contributions that hybridize with the underlying Mie‐void response. Rigorous coupled‐wave analysis shows that the dominant spectral transformation arises from replacing the semi‐infinite host with a finite SRN film, while the substrate acts as a secondary perturbation. Thickness‐dependent dispersion maps reveal an avoided crossing between interacting modes, identifying film thickness as a clean parameter for tracking the coupled modal evolution. Experimentally, we demonstrate depth‐dependent transmission spectra in good agreement with simulation, and realize visible structural colors and spatially encoded transmitted‐light patterns within a single metasurface architecture. These results establish transmission‐mode Mie‐void metasurfaces as a viable inverse‐dielectric platform for transmissive spectral filtering, optical encoding, and display‐oriented photonic elements.