High‐Efficiency Transmissive Programmable Metasurface for Multimode OAM Generation

Abstract

Metasurfaces have been extensively studied for generating electromagnetic waves carrying orbital angular momentum (OAM). In particular, programmable metasurfaces enable real‐time switching between multiple OAM modes in a digital manner. However, the current programmable metasurfaces are mostly based on reflective mode, which suffer from low efficiency as well as serious feed blockage. In this paper, a transmissive programmable metasurface is presented for the highly efficient generation of multimode convergent OAM beams. The proposed transmissive metasurface is composed of electronically reconfigurable units with 1‐bit phase resolution (0/π), which are obtained by integrating two PIN diodes in the radiating layer for current direction modulation. Through the antisymmetry configuration of the two PIN diodes, nearly uniform transmission magnitudes but inversed phase states in a wide band can be obtained. The simulation results show that the proposed reconfigurable unit can achieve good 1‐bit phase tuning, with minimum insertion loss of 0.2 dB and 2 dB transmission bandwidth of more than 10%. Through the dynamic modulation of the quantized code distributions on the metasurface, programmable multimode OAM beams can thus be constructed. Both simulated and measured results verify the effectiveness of the proposed design.

Electrically Reconfigurable Microwave Metasurfaces With Active Lumped Elements: A Mini Review

“…Perfect absorption occurs when the impedance of the dielectric substrate matches well with the free-space impedance while total reflection occurs when they mismatch. Similarly, switchable transmissive/absorptive metasurfaces have also been reported Bai et al (2020) with permission from John Wiley and Sons. .…”

Multifunctional Vortex Beam Generation by a Dynamic Reflective Metasurface

“…In order to make sure the proposed metasurface has a rotational symmetry structure and simple bias network for observation of rotational Doppler effect, a focusing phase distribution −2 πr xy /λ is not adopted in our design, where r xy is the radial distance from the phase center of horn feeder to the location ( x , y ), and λ is operating wavelength. [ 34 ]…”

Flexible Manipulation of Bessel‐Like Beams with a Reconfigurable Metasurface

“…[36][37][38] Recently, enormous attention has been concentrated on the design of reconfigurable metasurfaces. The dynamic manipulation ability of metasurface in microwave region is generally achieved by integrating adjustable elements such as varactor diodes, [39][40][41] PIN diodes, [42][43][44] liquid-filled resonators, [45,46] and microelectromechanical system (MEMS) switches. [47] Reconfigurable metasurfaces incorporating PIN diodes can realize only few discrete phase values, which can be limited for complex wavefront control.…”