Resonance characteristics of sub-wavelength high-refractive index dielectric metasurfaces as a function of lattice constant

Abstract

Sub-wavelength periodic nanostructures have unique properties that can lead to various applications in the field of photonics including cloaking, perfect absorption, perfect reflection and negative refractive index. Dielectric structures, unlike their metal counterparts, have low losses thus providing an alternative in various applications. In this work, we study the light-matter interaction in high refractive index dielectric periodic metasurfaces made of Tellurium cubes in air. In our earlier investigations in this direction with smaller periodicities, we observed a novel non-radiative state (anapole) immediately following a highly transparent state at higher frequencies and a reflection band at lower frequencies. In the current paper, we investigate the effect of periodicity of the metasurface on the response spectrum and most importantly on the observed transparent state. By studying the spatial distribution of the electric and magnetic fields and detailed multipole analysis, we see that the response spectrum is significantly affected by the periodicity of the metasurface. As the periodicity is increased, the band-like structure diminishes and a suppression of the electric dipole resonance is observed while the magnetic dipole resonance remains unaffected except for a shift towards lower frequencies. The highly transparent state which is a hybrid mode of electric dipole and quadrupole, however, is found to be independent of the periodicity of the structure, which has not been reported earlier in detail as per our knowledge.