# Designing Metagratings Via Local Periodic Approximation: From Microwaves to Infrared

## TL;DR

This paper introduces a simulation-based design method for metagratings that improves wavefront control by approximating local periodicity, applicable from microwaves to infrared, overcoming previous design limitations.

## Contribution

It presents a novel local periodic approximation approach for designing metagratings, enabling efficient and accurate unit cell-by-unit cell construction.

## Key findings

- Validated design approach with electric and magnetic metagratings
- Achieved improved wavefront manipulation efficiency
- Applicable across microwave to infrared frequencies

## Abstract

Recently, metamaterials-inspired diffraction gratings (or metagratings) have demonstrated unprecedented efficiency in wavefront manipulation by means of relatively simple structures. Conventional one-dimensional (1D) gratings have a profile modulation in one direction and a translation symmetry in the other. In 1D metagratings, the translation invariant direction is engineered at a subwavelength scale, which allows one to accurately control polarization line currents and, consequently, the scattering pattern. In bright contrast to metasurfaces, metagratings cannot be described by means of surface impedances (or local reflection and transmission coefficients). In this paper, we present a simulation-based design approach to construct metagratings in the "unit cell by unit cell" manner. It represents an analog of the local periodic approximation that has been used to design space-modulated metasurfaces and allows one to overcome the limitations of straightforward numerical optimization and semianalytical procedures that have been used to date to design metagratings. Electric and magnetic metagrating structures responding to, respectively, transverse electric and transverse magnetic incident plane waves are presented to validate the proposed design approach.