Angle-Tolerant Circular Eigenpolarizations Enabled by Orientational Disorder in Dielectric Metasurfaces

Tailored structural disorder in photonic metasurfaces enables advanced light shaping. Specifically, an orientational disorder in chiral nanostructures leads to circular eigenpolarizations with a heavily suppressed linear birefringence. The orientational disorder is, therefore, vital to observing purely chiroptical effects such as circular dichroism and optical activity. Here, it is experimentally and numerically demonstrated that all-dielectric orientationally disordered chiral bilayer square array metasurfaces preserve highly circular eigenpolarizations for a wide range of incidence angles. The angle-dependent performance of disordered chiral metasurfaces is compared with that of their C2 and C4 symmetric periodic counterparts, demonstrating that the disordered structures provide nearly pure circular eigenpolarizations across a larger range of angles and wavelengths, whereas the periodic ones do not. These findings underscore the ability of tailored disorder to enhance the robustness of engineered chiroptical responses of all-dielectric metasurfaces and highlight its potential for flat, integrable, and highly efficient optical components, such as circular polarizers and beam splitters.