Controlling Diffraction Patterns with Metagratings

Abstract

In this study we elaborate on the recent concept of metagratings proposed in Ra'di et al. [Phys. Rev. Lett. 119, 067404 (2017)] for efficient manipulation of reflected waves. Basically, a metagrating is a set of 1D arrays of polarization line currents which are engineered to cancel scattering in undesirable diffraction orders. We consider a general case of metagratings composed of N polarization electric line currents per supercell. This generalization is a necessary step to totally control diffraction patterns. We show that a metagrating having N equal to the number of plane waves scattered in the far-field can be used for controlling the diffraction pattern. To validate the developed theoretical approach, anomalous and multichannel reflections are demonstrated with 3D full-wave simulations in the microwave regime at 10 GHz. The results can be interesting for the metamaterials community as allow one to significantly decrease the number of used elements and simplify the design of wavefront manipulation devices, what is very convenient for optical and infra-red frequency ranges. Our findings also may serve as a way for development of efficient tunable antennas in the microwave domain.

Beamforming With Metagratings at Microwave Frequencies: Design Procedure and Experimental Demonstration

“…A plane-wave illumination is assumed and the wires interact only with the TE-polarized field. As it was shown in the theoretical study [53], the complex amplitudes A TE m of the electric field of the reflected plane waves are given by the following expression:…”

Generalized Space-Time-Periodic Diffraction Gratings: Theory and Applications

“…1(a), considering normal incidence of the input wave (θ i = 0), a symmetric diffraction pattern with respect to x = 0 will be produced by conventional static gratings, possessing a symmetric profile with respect to the x = 0 axis. An asymmetric diffraction pattern for normal incidence can be achieved by asymmetric static periodic metagratings [65,66]. However, gratings with symmetric and asymmetric profiles are both restricted by the Lortentz reciprocity theorem, and therefore, possess reciprocal diffraction transmission response.…”

Designing Metagratings via Local Periodic Approximation: From Microwaves to Infrared

“…Recently, metamaterials-inspired diffraction gratings have demonstrated unprecedented efficiency in manipulating scattering patterns with relatively simple structures [13][14][15][16][17][18]. Reflecting configuration of a metagrating represented by a one-dimensional periodic array of thin "wires" placed on top of a metal-backed dielectric substrate is illustrated in Fig.…”