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| 1 | Completely spin-decoupled geometric phase of a metasurface显示文摘Metasurfaces have provided an unprecedented degree of freedom(DOF)in the manipulation of electromagnetic waves.A geometric phase can be readily obtained by rotating the meta-atoms of a metasurface.Nevertheless,such geometric phases are usually spin-coupled,with the same magnitude but opposite signs for left-and right-handed circularly polarized(LCP and RCP)waves.To achieve independent control of LCP and RCP waves,it is crucial to obtain spin-decoupled geometric phases.In this paper,we propose to obtain completely spin-decoupled geometric phases by engineering the surface current paths on meta-atoms.Based on the rotational Doppler effect,the rotation manner is first analyzed,and it is found that the generation of a geometric phase lies in the rotation of the surface current paths on meta-atoms.Since the induced surface current paths under the LCP and RCP waves always start oppositely and are mirror-symmetrical with each other,it is natural that the geometric phases have the same magnitude and opposite signs when the meta-atoms are rotated.To obtain spin-decoupled geometric phases,the induced surface current under one spin should be rotated by one angle while the current under the other spin is rotated by a different angles.In this way,LCP and RCP waves can acquire different geometric phase changes.Proof-of-principle prototypes were designed,fabricated,and measured.Both the simulation and experiment results verify spin-decoupled geometric phases.This work provides a robust means to obtain a spindependent geometric phase and can be readily extended to higher frequency bands such as the terahertz,IR,and optical regimes. | XINMIN FU JIE YANG JIAFU WANG YAJUAN HAN CHANG DING TIANSHUO QIU BINGYUE QU LEI LI YONGFENG LI SHAOBO QU | 2023 | Photonics Research2023，11，7： | 1 |
| 2 | Remotely mind-controlled metasurface via brainwaves显示文摘The power of controlling objects with mind has captivated a popular fascination to human beings.One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces(PM),whose functions or operating modes can be switched or customized via on-site programming or pre-defined software.Nevertheless,most of existing PMs are wire-connected to users,manually-controlled and not real-time.Here,we propose the concept of remotely mind-controlled metasurface(RMCM)via brainwaves.Rather than DC voltage from power supply or AC voltages from signal generators,the metasurface is controlled by brainwaves collected in real time and transmitted wirelessly from the user.As an example,we demonstrated a RMCM whose scattering pattern can be altered dynamically according to the user’s brain waves via Bluetooth.The attention intensity information is extracted as the control signal and a mapping between attention intensity and scattering pattern of the metasurface is established.With such a framework,we experimentally demonstrated and verified a prototype of such metasurface system which can be remotely controlled by the user to modify its scattering pattern.This work paves a new way to intelligent metasurfaces and may find applications in health monitoring,5G/6G communications,smart sensors,etc. | Ruichao Zhu Jiafu Wang Tianshuo Qiu Yajuan Han Xinmin Fu Yuzhi Shi Xingsi Liu Tonghao Liu Zhongtao Zhang Zuntian Chu Cheng‑Wei Qiu Shaobo Qu | 2022 | eLight2022，2，1： | 1 |
| 3 | Direct field-to-pattern monolithic design of holographic metasurface via residual encoderdecoder convolutional neural network显示文摘Complex-amplitude holographic metasurfaces(CAHMs)with the flexibility in modulating phase and amplitude profiles have been used to manipulate the propagation of wavefront with an unprecedented level,leading to higher image-reconstruction quality compared with their natural counterparts.However,prevailing design methods of CAHMs are based on Huygens-Fresnel theory,meta-atom optimization,numerical simulation and experimental verification,which results in a consumption of computing resources.Here,we applied residual encoder-decoder convolutional neural network to directly map the electric field distributions and input images for monolithic metasurface design.A pretrained network is firstly trained by the electric field distributions calculated by diffraction theory,which is subsequently migrated as transfer learning framework to map the simulated electric field distributions and input images.The training results show that the normalized mean pixel error is about 3%on dataset.As verification,the metasurface prototypes are fabricated,simulated and measured.The reconstructed electric field of reverse-engineered metasurface exhibits high similarity to the target electric field,which demonstrates the effectiveness of our design.Encouragingly,this work provides a monolithic field-to-pattern design method for CAHMs,which paves a new route for the direct reconstruction of metasurfaces. | Ruichao Zhu Jiafu Wang Tianshuo Qiu Dingkang Yang Bo Feng Zuntian Chu Tonghao Liu Yajuan Han Hongya Chen Shaobo Qu | 2023 | Opto-Electronic Advances2023，6，8： | 0 |
| 4 | Six-channel programmable coding metasurface simultaneously for orthogonal circular and linear polarizations显示文摘Metasurfaces have intrigued long-standing research interests and developed multitudinous compelling applications owing to their unprecedented capability for manipulating electromagnetic waves,and the emerging programmable coding metasurfaces(PCMs)provide a real-time reconfigurable platform to dynamically implement customized functions.Nevertheless,most existing PCMs can only act on the single polarization state or perform in the limited polarization channel,which immensely restricts their practical application in multitask intelligent metadevices.Herein,an appealing strategy of the PCM is proposed to realize tunable functions in co-polarized reflection channels of orthogonal circularly polarized waves and in co-polarized and cross-polarized reflection channels of orthogonal linearly polarized waves from 9.0 to 10.5 GHz.In the above six channels,the spindecoupled programmable meta-atom can achieve high-efficiency reflection and 1-bit digital phase modulation by selecting the specific ON/OFF states of two diodes,and the phase coding sequence of the PCM is dynamically regulated by the field-programmable gate array to generate the desired function.A proof-of-concept prototype is constructed to verify the feasibility of our methodology,and numerous simulation and experimental results are in excellent agreement with the theoretical predictions.This inspiring design opens a new avenue for constructing intelligent metasurfaces with higher serviceability and flexibility,and has tremendous application potential in communication,sensing,and other multifunctional smart metadevices. | TONGHAO LIU YUEYU MENG JIAFU WANG HUA MA RUICHAO ZHU CHAO LIU WEIHAN LI ZUNTIAN CHU SAI SUI TIANSHUO QIU WENXUAN TANG SHAOBO QU | 2023 | Photonics Research2023，11，6： | 0 |
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