Phase-Gradient Metasurfaces Based on Local Fabry–Pérot Resonances

Abstract

In this work, we present a new mechanism for designing phase-gradient metasurfaces (PGMs) to control an electromagnetic wavefront with high efficiency. Specifically, we design a transmission-type PGM, formed by a periodic subwavelength metallic slit array filled with identical dielectrics of different heights. It is found that when Fabry–Pérot (FP) resonances occur locally inside the dielectric regions, in addition to the common phenomenon of complete transmission, the transmitted phase differences between two adjacent slits are exactly the same, being a nonzero constant. These local FP resonances ensure total phase shift across a supercell, fully covering a range of 0 to 2π, satisfying the design requirements of PGMs. Further research reveals that, due to local FP resonances, there is a one-to-one correspondence between the phase difference and the permittivity of the filled dielectric. A similar approach can be extended to the reflection-type case and other wavefront transformations, creating new opportunities for wave manipulation.

Novel silicon bipodal cylinders with controlled resonances and their use as beam steering metasurfaces

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Complex‐Amplitude Programmable Versatile Metasurface Platform Driven by Guided Wave

“…Metasurfaces, [ 1 , 2 ] the 2D version of metamaterials, possess the advantage of superior ability in wavefront tailoring. By changing the resonance characteristics, [ 3 , 4 ] transmission characteristics, [ 5 , 6 , 7 ] rotation symmetry, [ 8 , 9 ] and nonlinear feature [ 10 , 11 ] of the meta‐atom, the amplitude, [ 12 , 13 ] phase, [ 14 , 15 ] polarization, [ 16 , 17 ] and frequency [ 18 , 19 ] of EM waves can be manipulated. Various applications have been demonstrated such as beam scanning, [ 20 , 21 ] multi‐beam generation, [ 22 , 23 ] polarization transformation, [ 24 , 25 ] radar cross‐section reduction, [ 26 , 27 ] Airy beam generation, [ 28 , 29 , 30 , 31 ] image processing, [ 32 , 33 ] and focusing.…”

Highly efficient wavefront control based on extremely anisotropic materials

“…PGMs provide a novel way to control the propagation of * Authors to whom any correspondence should be addressed. light, which has enabled a large number of ultrathin devices to realize anomalous scattering [12][13][14][15][16][17][18], planar metalens [19,20], photonic spin Hall effect [21], surface waves [22] and so on. However, due to the surface impedance mismatching of PGMs, the wave control efficiency is usually not high.…”