Broadband, Multiband, and Multifunctional All-Dielectric Metasurfaces

All-dielectric bianisotropic metasurfaces with tailored polarization and spectral responses are studied, and a systematic approach to their design is developed. It is shown that a wide range of polarization transformations over broad bandwidths, as well as multiple bands, can be implemented by cascading subwavelength dielectric gratings. The subwavelength gratings, modeled as anisotropic layers, are cascaded to form metasurfaces that control the polarization of impinging waves. These metasurfaces are a low-loss alternative to their lossy, plasmonic counterparts at optical frequencies, and can replace conventional, bulky optical components. The multifunctional performance and compactness (wavelength-sized thickness) of the proposed devices will also find use at millimeter-wave frequencies. Example metasurfaces are presented and their performance is verified through full-wave simulation. This work demonstrates the flexibility with which cascaded subwavelength gratings can realize unprecedented polarization control with varied spectral responses.