Reciprocal Metasurfaces for On-axis Reflective Optical Computing

TL;DR

This paper introduces a reciprocal metasurface design enabling on-axis reflective optical computing, allowing dual-channel edge detection and derivative operations with simplified setup for ultrafast analog image processing.

Contribution

It presents a novel reciprocal metasurface approach that overcomes traditional Green's function challenges in on-axis reflective optical computing, enabling dual polarization channels.

Findings

Successfully designed an all-dielectric metasurface for edge detection

Demonstrated dual computing channels under orthogonal polarizations

Facilitated experimental setup for ultrafast optical signal processing

Abstract

Analog computing has emerged as a promising candidate for real-time and parallel continuous data processing. This paper presents a reciprocal way for realizing asymmetric optical transfer functions (OTFs) in the reflection side of the on-axis processing channels. It is rigorously demonstrated that the presence of Cross-polarization Exciting Normal Polarizabilities (CPENP) of a reciprocal metasurface circumvents the famous challenge of Green's function approach in implementation of on-axis reflective optical signal processing while providing dual computing channels under orthogonal polarizations. Following a comprehensive theoretical discussion and as a proof of concept, an all-dielectric optical metasurface is elaborately designed to exhibit the desired surface polarizabilities, thereby reflecting the first derivative and extracting the edges of images impinging from normal direction. The proposed study offers a flexible design method for on-axis metasurface-based optical signal processing and also, dramatically facilitates the experimental setup required for ultrafast analog computation and image processing.