Tunable reflective filters and perfect mirrors using all-dielectric metasurfaces

For several years, extensive research has focused on narrow and broadband optical filters and mirrors. The aim has been to achieve highly specific spectral responses across different wavelength bands. All-dielectric materials have been preferred due to their low losses and high-quality factor values. In this study, we present meta-resonators with concave and convex shapes to achieve both narrow and broad spectral responses. Numerical simulations based on the finite element method reveal a full width at half-maximum (FWHM) of 0.65 nm and 346 nm. The concave and convex designs improve light-matter interaction and enable tunability. Using an appropriate thermo-responsive or electro-responsive material as a covering layer, we successfully achieved precise tunability of 0.3 nm/10°C and 0.18 nm/V within the concave metasurface. These metasurfaces demonstrate nearly perfect reflectance, allowing them to behave as perfect mirrors for narrow and broadband line width applications.