Methodologies for On‐Demand Dispersion Engineering of Waves in Metasurfaces

Abstract

IntroductionMetasurfaces and surface waves are two booming research branches in modern optics and wave physics. As 2D counterparts of 3D metamaterials, metasurfaces have inherited many unusual properties of artificially structured metamaterials, e.g., negative refraction, super-resolution imaging, and invisibility. [1][2][3][4][5][6] Nevertheless, owing to the reduced dimension, metasurfaces are much easier to fabricate, thus providing possibilities to transform theoretical innovations to practical applications. [7,8] In principle, the mechanisms of light-matter interaction in metasurfaces are related to the exotic physical properties of surface waves on metasurfaces. There are many kinds of surface waves propagating along interfaces of two kinds of media, such as surface plasmons, Dyakonov, Bloch, and Tamm surface waves. [9,10] Surface plasmons require that one of the media has negative permittivity; Dyakonov surface waves require linear anisotropy of at least one of the media. Bloch and Tamm surface waves require periodic permittivity of one of the media truncated by the interface or along the interface. In this paper, we would like to highlight the Dispersion is one common yet critical property of all kinds of waves. It is related to the spatial and spectral evolution of waves in structured materials. This review gives a summary of the methodologies used for the on-demand dispersion engineering of waves in metasurfaces, which possess many unusual properties such as extremely short wavelength, diffraction-less directional propagation, and tunable phase shift, resulting in many exciting applications with performances beyond the limitations set by traditional geometric and physical optics. Since most metasurfaces could be continuously transformed from simple thin films, the methodologies proposed here are universal and may be applied to analyze and design various functional metasurfaces. Dispersion EngineeringWithout loss of generality, the geometry of almost all metasurfaces could be continuously transformed from simple thin films. The transformation process is illustrated in Figure 1. First, by stacking and bending multilayers, one obtain the superlens, planar hyperlens, and curved hyperlenses. [26][27][28] The hyperbolic dispersion in anisotropic metal-dielectric structures may lead to the formation of Dyakonov plasmons, which are similar to Dyakonov waves on anisotropic dielectric materials. [29][30][31][32][33][34] Second, a 90° rotation of the multilayer would result a 1D grating, which can be either periodic or gradient. Third,

Catenary Functions Meet Electromagnetic Waves: Opportunities and Promises

“…[37] By studying the physical mechanisms of coupled SPPs, the concept of digital M-waves was brought forward. [10,48] Based on the novel properties of M-waves and dispersion engineering methodologies, [50,140] subdiffraction-optics and flat optics rapidly developed, which finally lead to the formation of catenary optics. Since it could break the fundamental limitations of classical optics, such as the diffraction limit and Snell's law, catenary optics may become one cornerstone of the next generation of engineering optics, which we refer to as engineering optics 2.0.…”

“…[135] In recent years, there have been many types of research devoted to realizing achromatic flat lenses. [50,[136][137][138][139][140]…”

Large‐Area and Low‐Cost Nanoslit‐Based Flexible Metasurfaces for Multispectral Electromagnetic Wave Manipulation

“…However, this approach is time‐consuming, especially for the design of metasurfaces that possess multispectral manipulation. Recently, the electric field distribution and frequency‐dependent dispersion of M‐waves in metallic nanostructures were demonstrated to be well described by a catenary model, and an analytic method derived from catenary EM field theory was concluded to simplify the design (see Part I in the Supporting Information for a detailed description of catenary EM field theory). As mentioned in our previous works, in the simplest case of 1D metallic slits, the electric field distribution is mainly determined by the gap width w of the slits when the thickness t of the metasurface is in the deep‐subwavelength range (i.e., t << λ).…”

“…Thus far, many methods have been proposed to quantitatively optimize the EM response of metasurfaces . Recently, it was shown that the EM field distribution and frequency dispersion of meta‐surface‐waves (M‐waves) in a 1D metallic slit are well described by a catenary model, providing a useful way for simplifying the design of metasurface‐based devices …”

Features of transmission of electromagnetic waves through composite nanoresonators including epsilon-near-zero metamaterials

“…The progress in theory and technologies of nanophotonics, plasmonics, optics of metamaterials (MMs) and metasurfaces provided possibilities to reduce dimensions of many optical elements such as modulators, filters, absorbers, phase shifters, holograms, nanoresonators and others down to nanometer values (see, e.g. recent reviews [1][2][3][4][5][6][7][8][9][10][11][12] and numerous references in these works). The main purpose of such ultra-small devices is to control the radiation characteristics (amplitude, phase, polarization) at deeply subwavelength dimensions of a composite material or system.…”