Generation of steep phase anisotropy with zero-backscattering by arrays of coupled dielectric nano-resonators

The interaction of light with high-permittivity dielectric nano-resonators can lead to zero-backscattering (i.e., full transmission), attributed to the simultaneous excitation of electric and magnetic dipolar modes in these resonators. In this paper, we numerically demonstrate that 2-dimensional Si nanocuboid arrays with anisotropic periodicity and finely tuned cuboid height can generate up to 2π optical phase anisotropy with zero-backscattering. Especially, by introducing strong Fano-type coupling into unit cells of the array, the induced phase anisotropy becomes ultra-steep with excitation wavelength. These special optical properties promise applications in various transmissive photonic devices, and we discuss their potential applications in transmissive polarization conversion and sensing.