Cross-Polarization Effects in Metasurfaces Based on Nanoscale Silicon Cuboids with a Shape Defect: Implications for Polarization Conversion.

The problem of investigating the features of the anisotropic resonant response of single silicon nanoparticles with irregular shapes and metasurfaces fabricated from them is considered. The sizes of single nanoscale silicon cuboids were tuned for excitation of the dipole resonances in the near-infrared spectral range, and the metasurfaces composed of such nanoparticles were fabricated on a quartz substrate using lithographic methods. It is shown that the presence of the defect in the form of a cut edge of a nanoscale cuboid leads to the resonant excitation of minor components of the electric and magnetic dipole moments oriented perpendicularly to the polarization of the incident wave. The spectral position of such minor components for a cuboid with a defect corresponds to the position of the resonance of the main component for the same multipole in a cuboid without a defect. We performed the numerical optimization and determined the conditions for excitation of a resonant response for the cross-polarization component of the wave reflected from the metasurface composed of nanoscale cuboids with a defect. The developed method allows creating of the metasurfaces rotating the polarization plane, which can be used for the creation of the nanolayer polarization metacoatings allowing the polarization conversion. [ABSTRACT FROM AUTHOR]