Single‐Layer Bifacial Metasurface: Full‐Space Visible Light Control

Abstract

expansion order. Based on this parity, zero backward scattering is achievable under the condition that electric permittivity and magnetic permeability of the scattering body are equal to each other. [1] This effect is dubbed as Kerker effect, known to be due to destructive interference of the electric and magnetic mode radiation in the reflection space, which stems from various expansion orders of Mie scattering coefficients. [2][3][4][5] Metasurfaces, which indicate planar distribution of periodic or semiperiodic subwavelength scale structures, have been studied in various optical fields thanks to their unprecedented ability to control light properties. The ability to modulate electromagnetic characteristics in subwavelength scale, especially optical phase or amplitude, insure that metasurfaces are suitable for various applications such as hologram generation, [6,7] anomalous beam refraction, [8,9] color generation, [10,11] and orbital angular momentum generation. [12] They are also being studied for versatile functionalities as a means of replacing bulk optical components such as lens, [13,14] waveplates, [15] polarizers, [16,17] diffuser, [18] and retroreflector. [19] Recently, thanks to widespread attention of metamaterials in nanophotonics, the scattering radiation patterns including abovementioned multipolar phase effects are utilized for various optical or physical applications. [3,5,[20][21][22][23] For extended functionalities with respect to radiating pattern and corresponding efficiency to desired direction, generalized Kerker effect is exerting its influence as one of the important methods in the field of metaoptics. For instance, by overlapping ED and MD mode with identical value, Huygens' metasurface is proposed to suppress backward radiation, leading to high transmission efficiency. [24] Further interference of multipole mode radiations also enables directive radiation to reflection space, such as perfect magnetic mirrors as well. [25] By fine-tuning of the phase and amplitude ratio of each multipole mode, polarization-control metasurface, high-order diffraction control, and even directive dispersive device have been implemented so far. [26][27][28] Previously, full-space control has been studied as one of the significant metasurface researches; transmission-reflection integrated bifunctional and trifunctional metasurfaces were demonstrated by multilayered structure which operates in gigahertz range. [29,30] However, this more-than-one function device demands additional degrees of freedom in terms of design, so that the meta-atom should have large dimensions as well as Optical metasurfaces have attracted considerable attention thanks to their unprecedented ability to control the electromagnetic properties of light in subwavelength scale. These metasurface-integrated devices not only have the merit of compact form factor but also exhibit some better performance in comparison with conventional bulk optic devices. In this work, a novel metasurface that enables full-space light control is realized, off...

Progresses in the practical metasurface for holography and lens

“…As a result, it is possible to introduce an additional degree of freedom in phase modulation. Figure 2D shows the polarization multiplexing result when the phase detouring is combined with the PB phase [54]. As shown in Figure 2D, as the helicity of the incident light is altered, the reproduced CGH is flipped into the other one.…”

“…The study of metasurface holography has been carried out to increase the amount of information on one metasurface. This method is made possible by using a new structure, controlling the properties of incident light, or using a reflection space as modulating range with transmission space [21,[52][53][54][55][56][57][58][59]. The phase control via PB phase is well known to have a broadband characteristic [21,29,51].…”

“…The phase control via PB phase is well known to have a broadband characteristic [21,29,51]. However, if the resonant characteristic is added to the meta-atom for addition of auxiliary functionality or subsidiary information, the broadband operation becomes impossible [19,52,54]. Consequently, broadband-operating metasurfaces that can function beyond single phase control have also been studied [21,[60][61][62].…”

“…As a result, three different CGHs are imparted with a single metasurface at the optical frequency. Some studies have been made to control light in transmission and reflection space together [42,53,54,66,[92][93][94]. For instance, the structure shown in Figure 5B takes advantage of the fact that incident light is reflected when two transmitted lights are out of phase in the range where no diffraction order occurs [53].…”

“…Through a combination of two engineered meta-atoms, asymmetric transmission controlled by handedness is implemented, and by the in-plane rotation angle of the whole structure, phase modulation is achieved as well. Furthermore, as shown in Figure 5C, a bifacial metasurface has been designed to impart different CGHs in the transmission and reflection spaces simultaneously [54]. In addition to creating the same PB phase in the transmission and reflection spaces, independent phase control is achieved by controlling the phase difference between the two spaces by spatially varying the size of the meta-atom.…”