Silica Meta-Optics: When High Performance Does Not Need a High Index.

ABSTRACT: Metasurfaces, planar arrays of subwavelength nanostructures, are typically realized with high-index dielectrics, while low-index platforms are often dismissed due to weaker index contrast. We identify and experimentally verify regimes where a low-index platform (SiO₂) surpasses its high-index counterpart (TiO₂). A low index suppresses higher-order Bloch modes, enabling the design of efficient devices with relaxed feature sizes. Low-index metasurfaces also offer two intrinsic advantages: a broad, well-behaved chromatic response without explicit dispersion engineering and a strong tolerance to fabrication errors. We validate these features experimentally with silica metagratings, metalenses, and structured-light phase plates at λ = 632 nm. The metagratings reach ≥50% ab

SUBMITTER: Sacchi L 

PROVIDER: S-EPMC12715841 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature