Tailoring permittivity using metasurface: a facile way of enhancing extreme-angle transmissions for both TE- and TM-polarizations

Abstract

The transmission of electromagnetic (EM) waves through a dielectric plate will be decreased significantly when the incident angle becomes extremely large, regardless of transverse electric (TE)- or transverse magnetic (TM)- polarization. In this regard, we propose a facile way of tailoring the permittivity of the dielectric material using metasurface to enhance the transmissions of both TE- and TM-polarized waves under extremely large incidence angles. Due to parallel or antiparallel electric fields induced by the metasurface, the net electric susceptibility is altered, and hence the effective permittivity can be tailored to improve the impedance matching on the two air-dielectric interfaces, which enhances the wave transmissions significantly under extreme incident angles. As an example, we apply this method to a typical ceramic-matrix composite (CMC) plate. By incorporating orthogonal meta-gratings into the CMC plate, its effective permittivity is reduced for the TE-polarized waves but increased for the TM-polarized waves under the extreme incidence angle, which can reduce the impedance for the TE-polarization and increase the Brewster angle for the TM-polarization. Therefore, the impedance matchings for both TE- and TM-polarizations are improved simultaneously and dual-polarized transmission enhancements are achieved under the extreme angles. Here, the transmission responses have been numerically and investigated using the finite-difference-time-domain (FDTD) method. A proof-of-principle prototype is designed, fabricated, and measured to verify this method. Both numerical simulations and measurement results show that the prototype can operate under extremely large incidence angles θi∈[75°,85°] with significant transmission enhancement for both TE- and TM-polarizations compared to the pure dielectric plate. This work provides a facile way to enhance the transmissions under extreme angles and can be readily extended to terahertz and optical frequencies.

Anti-reflection metasurface synergizing plasma and lattice modes: an efficient route to wideband electromagnetic transparency under extreme angles

“…As shown in figure 5(b), especially at f 1 (ω 1 ), the effective relative permittivity of the plate is reduced down to 1 and the wave impedance of the CMC plate matches that of the air [27]. Due to the diluted effective permittivity above the plasma frequency, the impedance matching is improved and the transmission around f 1 is enhanced [28,29]. And since the plasma frequency is independent of the angle as shown in equation ( 8), the transmission enhancement characteristic exists at almost all angles (w p represents the plasma frequency, c 0 represents the speed of light in vacuum, a represents the space between long metallic wires-, and r the radius of long metallic wires [26,27]).…”

“…Then, we further propose to enhance TEand TM-polarization transmission simultaneously by adjusting the effective permittivity of dielectric plates. However, the anti-reflection bandwidth is still quite narrow under extreme angles [29]. It needs to be further developed broadband dual-polarization anti-reflection technology under extreme angles.…”

Tunable Quasi Bound States in the Continuum with High Q factor using Magneto-Optical Metasurface

“…Metasurface is characterized as a twodimensional planar device that can modulate the amplitude, phase, polarization and other parameters of electromagnetic waves [1][2][3][4][5][6][7]. Metasurface can modulate these wave parameters by changing geometric parameters [4,8,9]and material compositions of subwavelength unit [10][11][12]. Compared with traditional bulk materials, metasurface exhibits many unique advantages, such as lower loss, smaller footprint, simpler integration, easier fabrication, elaborate modulation, and so on [13,14].…”

Tunable quasi-bound states in the continuum in magneto-optical metasurfaces

“…Arbitrarily manipulating the fundamental parameters of light is one of the main targets in nanophotonics, and metasurfaces provide an operational platform for this objective. Metasurfaces are two-dimensional planar devices with artificial subwavelength unit cells that can modulate the amplitude, phase, polarization and other parameters of electromagnetic waves [1][2][3][4][5][6][7][8][9][10][11]. Once traditional metasurface devices are fabricated, their optical response cannot be adjusted.…”