Step Function in Momentum Space by a Metagrating

TL;DR

This paper demonstrates a novel metagrating design that creates a step function in momentum space, enabling abrupt control over light transmission and reflection, with potential applications in optical computing.

Contribution

It introduces a passive, reciprocal, and lossless metagrating that breaks mirror symmetry in angular transmittance to achieve a step function in momentum space.

Findings

Achieved abrupt switching from reflection to transmission in momentum space.

Demonstrated control over angular response of light using engineered metagratings.

Potential applications in optical spatial analog computing.

Abstract

Metasurface research has shown significant potential for controlling the polarization, amplitude, phase and propagation direction of light. Nevertheless, control over the angular response of incident light still remains a long-standing problem. In this work, we show the potential of diffractive systems for obtaining a step function in momentum space where the mirror symmetry of the angular transmittance is broken. By engineering the scattering response of an asymmetric particles in a metagrating, we could obtain such a step function in a passive, reciprocal, and lossless fashion. More specifically, the metagrating performs filtering in the momentum space with an abrupt switching from reflection to transmission for an incident electromagnetic wave with an arbitrary spatial profile. This metagrating may find diverse applications in the context of optical spatial analog computing. Moreover, it paves the way for exploring the capabilities of diffractive systems for gaining full control over the angular response of light using arbitrary momentum transfer functions.