Active metasurface in reflection manner for generation of reconfigurable OAM vortex beams

In this paper,we proposed an active metasurface in reflection manner that can generate reconfigurable OAM vortex beams with high purity in the X-band.The metasurface has a high reflectance of 0.94 and achieves a phase coverage of 320between 9.8 GHz and 11 GHz.Then,by encoding the phase distribution of the meta-atoms,various OAM vortex beams including 1,2,3,and 4 orders are generated,where the purity of all modes can be above 70%.Moreover,the metasurface can also deflect the OAM beam with a certain angle while maintaining high purity,which can be applied to reduce the influence of the alignment deviation between transmitting and receiving antennas during the communication processes.As a validation,the metasurface composed of 30×30 meta-atoms is fabricated and measured.Both simulation and measurement results demonstrate the capability of the proposed metasurface to generate reconfigurable OAM beams with high purity,indicating the application potentials of proposed meta-devices in future OAM communications.

Complementary transmissive ultra-thin meta-deflectors for broadband polarization-independent refractions in the microwave region

Polarization manipulation is a significant issue for artificial modulation of the electromagnetic(EM) wave, but general mechanisms all suffer the restriction of inherent symmetric properties between opposite handedness.Herein, a strategy to independently and arbitrarily manipulate the EM wave with orthogonal circular polarizations based on a metasurface is proposed, which effectually breaks through traditional symmetrical characteristics between orthogonal handedness. By synthesizing the propagation phase and geometric phase, the appropriate Jones matrix is calculated to obtain independent wavefront manipulation of EM waves with opposite circular polarizations. Two transmissive ultra-thin meta-deflectors are proposed to demonstrate the asymmetrical refraction of transmitted circularly polarized waves in the microwave region. Simulated transmitted phase front and measured far-field intensity distributions are in excellent agreement, indicating that the transmitted wave with different polarizations can be refracted into arbitrary and independent directions within a wide frequency band(relative bandwidth of 25%). The results presented in this paper provide more freedom for the manipulation of EM waves, and motivate the realizations of various polarization-independent properties for all frequency spectra.

Dual-band independent phase control based on high efficiency metasurface[Invited]

A general method to realize arbitrary dual-band independent phase control is proposed and demonstrated in this paper.A double-layered C-shape reflective meta-atom is designed to realize independent phase control with high efficiency.As a proof of concept,we propose two functional metasurfaces in the microwave region;the first metasurface performs beam steering in different directions,and the second metasurface generates achromatic beam steering at two distinct frequencies.Both simulation and measurement results agree well with the theoretical pre-setting.The maximum measured efficiency is 88.7%and 92.3%at 6.8 GHz and 8.0 GHz,respectively,for one metasurface,and 91.0%and 89.8%at 6.9 GHz and8.6 GHz,respectively,for the other.