From parabolic-trough to metasurface-concentrator

TL;DR

This paper introduces a new method to evaluate the quality and fabrication tolerance of metasurfaces for flat optics by adapting parameters from solar concentrator optics and demonstrating their application through numerical examples.

Contribution

It proposes definitions and a calculation approach for intercept factor and slope error in physical optics, enabling better assessment of metasurface performance and fabrication sensitivity.

Findings

Designed three metasurface concentrators and evaluated their efficiency.

Assessed sensitivities to fabrication imperfections.

Provided a framework for comparing metasurface performance.

Abstract

Metasurfaces are promising tools towards novel designs for flat optics applications. As such their quality and tolerance to fabrication imperfections need to be evaluated with specific tools. However, most such tools rely on the geometrical optics approximation and are not straightforwardly applicable to metasurfaces. In this Letter, we introduce and evaluate, for metasurfaces, parameters such as the intercept factor and the slope error usually defined for solar concentrators in the realm of ray-optics. After proposing definitions valid in physical optics, we put forward an approach to calculate them. As examples, we design three different concentrators based on three specific unit cells and assess them numerically. The concept allows for the comparison of the efficiency of the metasurfaces, their sensitivities to fabrication imperfections and will be critical for practical systems.