# High-transmissivity Silicon Visible-wavelength Metasurface Designs based on Truncated-cone Nanoantennae

## TL;DR

This paper presents a numerical study of silicon-based metasurfaces with stepped truncated cone nanoantennas, achieving high transmittance and full phase control in the visible spectrum for ultra-compact optical devices.

## Contribution

It introduces a novel stepped truncated cone nanoantenna design for silicon metasurfaces, enabling improved phase coverage and transmittance in the 700-800nm range.

## Key findings

- Achieves full cycle phase response from 0 to pi.
- Improves transmittance compared to cylindrical geometries.
- Designs operational in the 700-800nm wavelength window.

## Abstract

High-transmissivity all-dielectric metasurfaces have recently attracted attention towards the realization of ultra-compact optical devices and systems. Silicon based metasurfaces, in particular, are highly promising considering the possibility of monolithic integration with VLSI circuits. Realization of silicon based metasurfaces operational in the visible wavelengths remains a challenge. A numerical study of silicon metasurfaces based on stepped truncated cone shaped nanoantenna elements is presented. Metasurfaces based on the stepped conical geometry can be designed for operation in the 700nm to 800nm wavelength window and achieve full cycle phase response (0 to pi with an improved transmittance in comparison with previously reported cylindrical geometry [1]. A systematic parameter study of the influence of various geometrical parameters on the achievable amplitude and phase coverage is reported.