Metasurfaces and their applications

Abstract

Metasurfaces are a topic of significant research and are used in various applications due to their unique ability to manipulate electromagnetic waves in microwave and optical frequencies. These artificial sheet materials, which are usually composed of metallic patches or dielectric etchings in planar or multi-layer configurations with subwavelength thickness, have the advantages of light weight, ease of fabrication, and ability to control wave propagation both on the surface and in the surrounding free space. Recent progress in the field has been classified by application and reviewed in this article. Starting with the development of frequency-selective surfaces and metamaterials, the unique capabilities of different kinds of metasurfaces have been highlighted. Surface impedance can be varied and manipulated by patterning the metasurface unit cells, which has broad applications in surface wave absorbers and surface waveguides. They also enable beam shaping in both transmission and reflection. Another important application is to radiate in a leaky wave mode as an antenna. Other applications of metasurfaces include cloaking, polarizers, and modulators. The controllable surface refractive index provided by metasurfaces can also be applied to lenses. When active and non-linear components are added to traditional metasurfaces, exceptional tunability and switching ability are enabled. Finally, metasurfaces allow applications in new forms of imaging.

Ultrathin Single Layer Metasurfaces with Ultra‐Wideband Operation for Both Transmission and Reflection

“…It is worth noting that since the wideband circular polarized antennas used in our measurement are not perfect with axial ratio equals to 1, other unexpected modes are also observed in Figure 4. Due to limited experimental setup, the higher frequency range (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30) results are solely numerically verified and are presented in Figures S6 and S7 (Supporting Information).…”

“…In microwave, however, very few efforts have been made to the improvement of metasurfaces' operation bandwidths. A common approach is to cascade multiple layers of dielectric, air, and metal 24,28–30. To the best of our knowledge, the widest operation bandwidth of transmissive metasurfaces reported so far is 36%31 for cascaded design and 24%32 for single‐layer metasurface.…”

“…A common approach is to cascade multiple layers of dielectric, air, and metal. [24,[28][29][30] To the best of our knowledge, the widest operation bandwidth of transmissive metasurfaces reported so far is 36% [31] for cascaded design and 24% [32] for single-layer metasurface. Moreover, the metasurfaces working in both transmission and reflection are recently realized in optical domain.…”

Mobility-Aware Beam Steering in Metasurface-Based Programmable Wireless Environments

“…• Minimize the networking delay, τ → n + τ ← n , and the queuing delay, τ q , via appropriate routing and scheduling techniques, thereby minimizing the user dislocation via relation (2). • Forecast the expected user location at time t + τ tot and produce the corresponding HSF configuration at step 4 (rather than configuring it for time t).…”

“…Software-defined Metasurfaces (SDMs) have received considerable attention, due to their efficiency in exerting control over electromagnetic (EM) waves during their propagation from a transmitter to a receiver [1]. SDMs allow for precise control over the direction, polarization, amplitude and phase of waves impinging over them, in a frequency and encodingselective manner [2]- [4]. Moreover, metasurface hypervisors called HyperSurfaces (HSFs) have been proposed, which allow for chaining and exerting many wave manipulation functionalities at once via well-defined application programming interfaces [5].…”