Bi-layered coded metasurface for multi-functional hologram with broadband transmission and efficient reflection

A multi-functional full-space metasurface based on frequency and polarization multiplexing is proposed.The metasurface unit consists of metallic patterns printed on the two faces of a single-layered dielectric substrate.The unit cell can control electromagnetic wavefronts to achieve a broadband transmission with amplitudes greater than 0.4 from 4.4 to 10.4 GHz.Meanwhile,at 11.7 GHz and 15.4 GHz,four high-efficiency reflection channels with a reflection amplitude greater than 0.8 are also realized.When illuminated by linearly polarized waves,five different functions can be realized at five different frequencies,which are demonstrated by theoretical calculations,full-wave simulations,and experimental measurements.

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.

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.

Versatile metasurface platform for electromagnetic wave tailoring

The emergence of metasurfaces provides a novel strategy to tailor the electromagnetic response of electromagnetic waves in a controlled manner by judicious design of the constitutive meta-atom.However,passive metasurfaces tend to perform a specific or limited number of functionalities and suffer from narrow-frequency-band operation.Reported reconfigurable metasurfaces can generally be controlled only in a 1D configuration or use p-i-n diodes to show binary phase states.Here,a 2D reconfigurable reflective metasurface with individually addressable meta-atoms enabling a continuous phase control is proposed in the microwave regime.The response of the meta-atom is flexibly controlled by changing the bias voltage applied to the embedded varactor diode through an elaborated power supply system.By assigning appropriate phase profiles to the metasurface through voltage modulation,complex beam generation,including Bessel beams,vortex beams,and Airy beams,is fulfilled to demonstrate the accurate phase-control capability of the reconfigurable metasurface.Both simulations and measurements are performed as a proof of concept and show good agreement.The proposed design paves the way toward the achievement of real-time and programmable multifunctional meta-devices,with enormous potential for microwave applications such as wireless communication,electromagnetic imaging,and smart antennas.

Compact logic operator utilizing a single-layer metasurface

In this paper, we design and demonstrate a compact logic operator based on a single-layer metasurface at microwave frequency. By mapping the nodes in the trained fully connected neural network(FCNN) to the specific unit cells with phase control function of the metasurface, a logic operator with only one hidden layer is physically realized. When the incident wave illuminates specific operating regions of the metasurface, corresponding unit cells are activated and can scatter the incident wave to two designated zones containing logical information in the output layer. The proposed metasurface logic operator is experimentally verified to achieve three basic logic operations(NOT, OR, and AND) under different input signals. Our design shows great application potential in compact optical systems, low-power consumption information transmission, and ultrafast wave-based full signal processing.