Controllably asymmetric beam splitting via gap-induced diffraction channel transition in dual-layer binary metagratings

Abstract

In this work, we designed and studied a feasible dual-layer binary metagrating, which can realize controllable asymmetric transmission and beam splitting with nearly perfect performance. Owing to ingenious geometry configuration, only one meta-atom is required to design for the metagrating system. By simply controlling air gap between dual-layer metagratings, high-efficiency beam splitting can be well switched from asymmetric transmission to symmetric transmission. The working principle lies on gap-induced diffraction channel transition for incident waves from opposite directions. The asymmetric/symmetric transmission can work in a certain frequency band and a wide incident range. Compared with previous methods using acoustic metasurfaces, our approach has the advantages of simple design and tunable property and shows promise for applications in wavefront manipulation, noise control and acoustic diode.

Sound vortex diffraction via topological charge in phase gradient metagratings

“…2C ), the reflection efficiency of l r = 1 greatly reduces with the increase in the number of unit cells, as shown in fig. S9A, and therefore, PGMs with simplified design ( 41 , 42 ) can be used to reduce the undesired absorption. While for the SV with l in = − 1, the transmitted SV via the lower diffraction order (i.e., Eq.…”

Polarization-dependent asymmetric transmission using a bifacial metasurface

“…The detailed information of how the light trajectory is determined is discussed in part 2 This journal is © The Royal Society of Chemistry 2020 of the ESI. † In short, this phenomenon can be summarized with the abovementioned parameters, as revealed by previous studies, expressed as: 35,[37][38][39] L = m + n.…”

“…This is called the critical angle condition, and the resultant diffraction is different from GSL. In the critical angle condition, the manner in which the light proceeds cannot be explained by GSL, and it is determined by the following equation, called the diffraction law of parity reversal: 35,39 k t,r = k in + x + (n À 1)G = k in + nG,…”

“…Next, for a numerical demonstration of the induced reflection L = 2, the supercell structure consists of two meta-atoms (m = 2) for exhibiting the phase gradient x = p/P. Because the structure is composed of two meta-atoms, the diffraction law of eqn (4) is modified as below: 39 k t,r = k in AE nG.…”

“…[35][36][37][38] However, while the inherited physics has been theoretically revealed in past studies, devices utilizing the relevant content is still rare. 39,40 Because the current research framework of metasurfaces which modulate full space lacks polarization response, the combination of the phase gradient for asymmetric transmission and a conventional polarization multiplexing scheme may pave the way to achieve novel polarization-selective full-space control in the electromagnetic regime. 14,15,35 In this article, a metasurface platform is proposed which achieves asymmetric transmission according to the polarization states of incident light and conveys two independent phase profiles to each space at the same time.…”