# Metasurface-Enhanced Transparency

## TL;DR

This paper explores how diffractive metasurfaces can enhance light transmission across high to low refractive index interfaces, optimizing interface profiles to improve out-coupling efficiency within fundamental physical limits.

## Contribution

It introduces a numerical optimization approach for metasurface profiles to maximize light out-coupling and identifies universal transmission limits based on dielectric properties.

## Key findings

- Metasurfaces can improve out-coupling for various incident angles.
- A universal limit for transmission efficiency exists, independent of metasurface design.
- Optimization of interface profiles can approach this fundamental limit.

## Abstract

We consider the problem of light transmission from a high refractive index medium into a low index environment. While total internal reflection severely limits such transmission in systems with smooth interfaces, diffractive metasurfaces may help out-couple light that enters an interface at blazing angles. We demonstrate that the profile of the structured interface can be numerically optimized to target a particular emission pattern. Our study suggests that while metasurfaces can help to out-couple light from a range of incident directions, there exists a universal limit for total transmission efficiency that depends only on the dielectric properties of the two materials and is independent of the profile and the composition of the metasurface coupler.

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Source: https://tomesphere.com/paper/1701.05867