Abstract

Metasurfaces (MSs), the two-dimensional version of metamaterials, are made of arrangements of sub-wavelength meta-atoms, capable to modulate the optical responses of the incident light [3]. There exist different approaches for the design of metasurfaces, broadly classified according to the physical mechanism used by the meta-atoms to control the phase and amplitude of the scattered light. In all approaches, the material of choice for the meta-atoms is of great importance. Amongst the most popular materials for dielectric metasurfaces are Titanium dioxide (TiO₂) and amorphous silicon, both having high refractive index and broadband transparency. While both materials offer excellent performance in metasurfaces applications, they require high deposition temperature over long periods (TiO2) and their operation bandwidth does not extend to short visible wavelengths (amorphous silicon).

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