Switchable Metasurface With Broadband and Highly Efficient Electromagnetic Functionality

Zeyong Wei,Xiaoqin Liu,Yang Cao

doi:10.3389/fphy.2020.00090

Abstract

Electromagnetic metasurface is a kind of artificial electromagnetic structure, which can control the transmission, reflection, polarization and beam of electromagnetic wave within sub-wavelength thickness. Efficiency, bandwidth and dynamic control are very important in the application of metasurface. The bandwidth of electromagnetic transparency can be broadened by interlayer coupling of local resonance modes of the stacked layers. In this paper, we propose that the electromagnetic wave could be switched on or off in a broadband frequency range by metasurface which consists of three layers of metal microstructures with PIN diodes. When the diodes are biased with forward voltage, the switching diodes are in the on state, and the slab reflects electromagnetic wave completely, just like a perfect metal. When the diodes are biased with backward voltage, the switching diodes are equivalent to a capacitor, and all the electromagnetic wave energy passes through the sample. The simulation results show that the transmissivity is less than 1% when the sample is loaded with forward voltage in the frequency range of 8-12GHz, while the transmittance is more than 96% when the sample is loaded with reverse bias. We have fabricated the corresponding samples and measured the reflection and transmission in the waveguide. The measurements verify the properties of broadband highly efficient electromagnetic transparency and perfect reflection.

Highlights

Manipulating the amplitude and phase of the electromagnetic waves in a desired manner has broad applicability in areas such as imaging, sensing, and communication [1]
Due to the resonant feature of artificial structures, it is very difficult to manipulate the electromagnetic wave in a broadband frequency range, and metasurfaces only exhibit fascinating
When the PIN diodes are loaded with forward bias voltage, the transmission is suppressed below 1%, while the reflectivity reaches 88%

Summary

INTRODUCTION

Manipulating the amplitude and phase of the electromagnetic waves in a desired manner has broad applicability in areas such as imaging, sensing, and communication [1]. When the PIN diodes are loaded with forward bias voltage, the transmission is suppressed below 1%, while the reflectivity reaches 88% It can be observed from the field distributions that the electromagnetic transparency comes from the near-field coupling of the magnetic resonance modes [23, 47–51]. The diodes work as capacitors while they are not biased or loaded with reverse bias voltage (Off-State) In this instance, the gratings together with the metallic mesh in the middle layer form a kind of magnetic resonant structure. As the bandwidth of transparent state can be broadened by the near-field coupling of the resonance modes in the metasurface, the coupling coefficient can be adjusted by metallic mesh in the middle layer. As the value of wm increases, the transparency bandwidth becomes narrower, which agrees well with the theoretical prediction

CONCLUSION

Findings

DATA AVAILABILITY STATEMENT