Polarization-Independent Broadband Angular Selectivity Based on Anisotropic Diamagnetic Metamaterial

Achieving broadband angular selectivity has been attracting much interest from both scientists and engineers in recent years. Previous experimental demonstrations have been limited to the
$p$
-polarized incidence. Here, we propose a universal approach to achieve polarization-independent broadband angular selectivity by introducing electrically and magnetically anisotropic diamagnetic medium into multiple 1-D photonic crystal stacks. Such stacks have a broadband angular photonic bandgap for both
$s$
- and
$p$
-polarized waves. The anisotropic diamagnetic medium is artificially constructed with periodically arranged close metallic ring arrays, which exhibits a negligible frequency dispersion in an ultrawide band. As a proof of principle, one stack of photonic structures for the normal-incidence-selective case is fabricated and measured in the microwave region. The proposed approach is simple, robust, and scalable from near-zero frequencies to terahertz frequencies, showing promising practical applications such as spatial filters and anti-jamming communications.