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| 1 | Smart metasurface with self-adaptively reprogrammable functions显示文摘Intelligence at either the material or metamaterial level is a goal that researchers have been pursuing.From passive to active,metasurfaces have been developed to be programmable to dynamically and arbitrarily manipulate electromagnetic(EM)wavefields.However,the programmable metasurfaces require manual control to switch among different functionalities.Here,we put forth a smart metasurface that has self-adaptively reprogrammable functionalities without human participation.The smart metasurface is capable of sensing ambient environments by integrating an additional sensor(s)and can adaptively adjust its EM operational functionality through an unmanned sensing feedback system.As an illustrative example,we experimentally develop a motion-sensitive smart metasurface integrated with a three-axis gyroscope,which can adjust self-adaptively the EM radiation beams via different rotations of the metasurface.We develop an online feedback algorithm as the control software to make the smart metasurface achieve single-beam and multibeam steering and other dynamic reactions adaptively.The proposed metasurface is extendable to other physical sensors to detect the humidity,temperature,illuminating light,and so on.Our strategy will open up a new avenue for future unmanned devices that are consistent with the ambient environment. | Qian Ma Guo Dong Bai Hong Bo Jing Cheng Yang Lianlin Li Tie Jun Cui | 2019 | Light(Science & Applications)2019，8，1： | 13 |
| 2 | Accurate and broadband manipulations of harmonic amplitudes and phases to reach 256 QAM millimeter-wave wireless communications by time-domain digital coding metasurface显示文摘We propose a theoretical mechanism and new coding strategy to realize extremely accurate manipulations of nonlinear electromagnetic harmonics in ultrawide frequency band based on a time-domain digital coding metasurface(TDCM).Using the proposed mechanism and coding strategy,we design and fabricate a millimeter-wave(mmWave) TDCM,which is composed of reprogrammable meta-atoms embedded with positive-intrinsic-negative diodes.By controlling the duty ratios and time delays of the digital coding sequences loaded on a TDCM,experimental results show that both amplitudes and phases of different harmonics can be engineered at will simultaneously and precisely in broad frequency band from 22 to33 GHz,even when the coding states are imperfect,which is in good agreement with theoretical calculations.Based on the fabricated high-performance TDCM,we further propose and experimentally realize a large-capacity mmWave wireless communication system,where 256 quadrature amplitude modulation,along with other schemes,is demonstrated.The new wireless communication system has a much simpler architecture than the currently used mmWave wireless systems,and hence can significantly reduce the hardware cost.We believe that the proposed method and system architecture can find vast application in future mmWave and terahertz-wave wireless communication and radar systems. | Ming Zheng Chen Wankai Tang Jun Yan Dai Jun Chen Ke Lei Zhang Cheng Zhang Jin Yang Lianlin Li Qiang Cheng Shi Jin Tie Jun Cui | 2022 | National Science Review2022，9，1： | 13 |
| 3 | Intelligent coding metasurface holograms by physics-assisted unsupervised generative adversarial network显示文摘Intelligent coding metasurface is a kind of information-carrying metasurface that can manipulate electromagnetic waves and associate digital information simultaneously in a smart way.One of its widely explored applications is to develop advanced schemes of dynamic holographic imaging.By now,the controlling coding sequences of the metasurface are usually designed by performing iterative approaches,including the Gerchberg–Saxton(GS)algorithm and stochastic optimization algorithm,which set a large barrier on the deployment of the intelligent coding metasurface in many practical scenarios with strong demands on high efficiency and capability.Here,we propose an efficient non-iterative algorithm for designing intelligent coding metasurface holograms in the context of unsupervised conditional generative adversarial networks(cGANs),which is referred to as physics-driven variational auto-encoder(VAE)cGAN(VAE-cGAN).Sharply different from the conventional cGAN with a harsh requirement on a large amount of manual-marked training data,the proposed VAE-cGAN behaves in a physics-driving way and thus can fundamentally remove the difficulties in the conventional cGAN.Specifically,the physical operation mechanism between the electric-field distribution and metasurface is introduced to model the VAE decoding module of the developed VAE-cGAN.Selected simulation and experimental results have been provided to demonstrate the state-of-the-art reliability and high efficiency of our VAE-cGAN.It could be faithfully expected that smart holograms could be developed by deploying our VAE-cGAN on neural network chips,finding more valuable applications in communication,microscopy,and so on. | Che Liu Wen Ming Yu Qian Ma Lianlin Li Tie Jun Cui | 2021 | Photonics Research2021，9，4： | 7 |
| 4 | Intelligent metasurfaces:control,communication and computing显示文摘Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern society.Intelligent metasurfaces are smart platforms to manipulate the wave-information-matter interactions without manual intervention by synergizing engineered ultrathin structures with active devices and algorithms,which evolve from the passive composite materials for tailoring wave-matter interactions that cannot be achieved in nature.Here,we review the recent progress of intelligent metasurfaces in wave-information-matter controls by providing the historical background and underlying physical mechanisms.Then we explore the application of intelligent metasurfaces in developing novel wireless communication architectures,with particular emphasis on metasurface-modulated backscatter wireless communications.We also explore the wave-based computing by using the intelligent metasurfaces,focusing on the emerging research direction in intelligent sensing.Finally,we comment on the challenges and highlight the potential routes for the further developments of the intelligent metasurfaces for controls,communications and computing. | Lianlin Li Hanting Zhao Che Liu Long Li Tie Jun Cui | 2022 | eLight2022，2，1： | 7 |
| 5 | Information theory of metasurfaces显示文摘We propose a theory to characterize the information and information processing abilities of metasurfaces,and demonstrate the relation between the information of the metasurface and its radiation pattern in the far-field region.By incorporating a general aperturemodel with uncertainty relation in L2-space,we propose a theory to predict the upper bound of information contained in the radiation pattern of a metasurface,and reveal the theoretical upper limit of orthogonal radiation states.Theproposed theory also provides guidance for inverse design of the metasurface with respect to given functionalities.Through investigation of the information of disordered-phase modulated metasurfaces,we find the information invariance(1?γ,whereγis Euler’s constant)of chaotic radiation patterns.That is to say,the information of the disordered-phase modulated radiation patterns is always equal to 1?γ,regardless of variations in size,the number of elements and the phase pattern of metasurface.This value might be the lower bound of radiation-pattern information of the metasurface,which can provide a theoretical limit for information modulation applications,including computational imaging,stealth technologies and wireless communications. | Haotian Wu Guo Dong Bai Shuo Liu Lianlin Li Xiang Wan Qiang Cheng Tie Jun Cui | 2020 | National Science Review2020，7，3： | 5 |
| 6 | Intelligent metasurface imager and recognizer显示文摘There is an increasing need to remotely monitor people in daily life using radio-frequency probe signals.However,conventional systems can hardly be deployed in real-world settings since they typically require objects to either deliberately cooperate or carry a wireless active device or identification tag.To accomplish complicated successive tasks using a single device in real time,we propose the simultaneous use of a smart metasurface imager and recognizer,empowered by a network of artificial neural networks(ANNs)for adaptively controlling data flow.Here,three ANNs are employed in an integrated hierarchy,transforming measured microwave data into images of the whole human body,classifying specifically designated spots(hand and chest)within the whole image,and recognizing human hand signs instantly at a Wi-Fi frequency of 2.4 GHz.Instantaneous in situ full-scene imaging and adaptive recognition of hand signs and vital signs of multiple non-cooperative people were experimentally demonstrated.We also show that the proposed intelligent metasurface system works well even when it is passively excited by stray Wi-Fi signals that ubiquitously exist in our daily lives.The reported strategy could open up a new avenue for future smart cities,smart homes,human-device interaction interfaces,health monitoring,and safety screening free of visual privacy issues. | Lianlin Li Ya Shuang Qian Ma Haoyang Li Hanting Zhao Menglin Wei Che Liu Chenglong Hao Cheng-Wei Qiu Tie Jun Cui | 2019 | Light(Science & Applications)2019，8，1： | 5 |
| 7 | High-efficiency broadband polarization-independent superscatterer using conformal metasurfaces显示文摘Safe detection of an arbitrarily shaped platform is critical for survivability, rescue, or navigation safety in a remote region. Metasurfaces afford great potential due to their strong electromagnetic(EM) wave control. However,studies have mainly focused on the physics and design of metasurfaces on planar plates, which does not satisfy the current requirements of aerodynamics and aesthetics. Herein, we propose a sophisticated strategy to design a metasurface that can wrap over arbitrarily shaped objects with moderate curvature on which optical aberrations are commonly introduced. By designing each meta-atom on the basis of the required position and phase compensation, exact EM wavefronts are restored. For verification, several conformal metasurfaces were designed and numerically studied on metallic cylinders at the microwave spectrum. A proof-of-concept device is fabricated and is experimentally characterized. The results demonstrate the availability of the desirable dual-beam superscatterer with strong backscattering enhancement toward two directions, thus indicating that the distortions induced by an arbitrary platform can be efficiently corrected. Our method affords an efficient alternative for designing highperformance multifunctional optoelectronic devices equipped on a moderately curved platform. | HE-XIU XU SHIWEI TANG CHEN SUN LIANLIN LI HAIWEN LIU XINMI YANG FANG YUAN YUNMING SUN | 2018 | Photonics Research2018，6，8： | 3 |
| 8 | One-bit quantization is good for programmable coding metasurfaces显示文摘The information-carrying programmable metasurfaces have found widespread applications in communication, sensing, and other related areas. However, there is a fundamental but unresolved problem,i.e., the rigorous understanding of the quantization of metasurface coding. Here, we theoretically investigate the performance difference between one-bit and continuous information-encoding metasurfaces. To this end,we derive analytical representations of system responses in various cases(single-input single-output, singleinput multiple-output, and multiple-input multiple-output). We analyze the impact of one-bit coding(in contrast to continuous coding) in terms of the resulting channel cross-talk and reduction of information capacity in various representative scenarios from wireless communication and holography. Our main finding indicates that the one-bit coding yields a satisfactory performance in most practical scenarios;we also show that in many cases there are smart ways to mildly relax optimization constraints in order to reduce the performance gap between the one-bit and continuous coding. We expect that our results can provide theoretical guidance for a large variety of metasurface-assisted information systems for electromagnetic waves and other wave phenomena. | Ya SHUANG Hanting ZHAO Menglin WEI Qiang CHENG Shi JIN Tiejun CUI Philipp DEL HOUGNE Lianlin LI | 2022 | Science China(Information Sciences)2022，65，7： | 2 |
| 9 | SAR Imaging Degradation by Iono- spheric Irregularities Based on TFTPCF Analysis显示文摘 | Li Lianlin Li Fang | 2007 | IEEE Trans on Geoscience and Remote Sensing2007，45，5： | 1 |
| 10 | Information metasurfaces and intelligent metasurfaces显示文摘Metamaterials and metasurfaces have inspired worldwide interest in the recent two decades due to their extraordinary performance in controlling material parameters and electromagnetic properties.However,most studies on metamaterials and metasurfaces are focused on manipulations of electromagnetic fields and waves,because of their analog natures.The concepts of digital coding and programmable metasurfaces proposed in 2014 have opened a new perspective to characterize and design metasurfaces in a digital way,and made it possible to control electromagnetic fields/waves and process digital information simultaneously,yielding the birth of a new direction of information metasurfaces.On the other hand,artificial intelligence(AI)has become more important in automatic designs of metasurfaces.In this review paper,we first show the intrinsic natures and advantages of information metasurfaces,including information operations,programmable and real-time control capabilities,and space–time-coding strategies.Then we introduce the recent advances in designing metasurfaces using AI technologies,and particularly discuss the close combinations of information metasurfaces and AI to generate intelligent metasurfaces.We present self-adaptively smart metasurfaces,AI-based intelligent imagers,microwave cameras,and programmable AI machines based on optical neural networks.Finally,we indicate the challenges,applications,and future directions of information and intelligent metasurfaces. | Qian Ma Che Liu Qiang Xiao Ze Gu Xinxin Gao Lianlin Li Tie Jun Cui | 2022 | Photonics Insights2022，1，1： | 1 |
| 11 | A Novel AutofocusingApproach for Real-Time Through-Wall Imaging Under Un-known Wall Parameters 显示文摘 | Li Lianlin Zhang Wenji Li Fang | 2010 | IEEE Transactions on Geo-science and Remote Sensing2010，48，1： | 1 |
| 12 | Tomographic reconstruction using the distorted Rytov iterative method with phaseless data 显示文摘 | Li Lianlin Zhang Wenji Li Fang | 2008 | IEEE Tran Geoscience and Remote Sensing Letters2008，5，3： | 1 |
| 13 | Harmonic information transitions of spatiotemporal metasurfaces显示文摘Facilitated by ultrafast dynamic modulations,spatiotemporal metasurfaces have been identified as a pivotal platform for manipulating electromagnetic waves and creating exotic physical phenomena,such as dispersion cancellation,Lorentz reciprocity breakage,and Doppler illusions.Motivated by emerging information-oriented technologies,we hereby probe the information transition mechanisms induced by spatiotemporal variations and present a general model to characterize the information processing capabilities of the spatiotemporal metasurface.Group theory and abstract number theory are adopted through this investigation,by which the group extension and independent controls of multiple harmonics are proposed and demonstrated as two major tools for information transitions from the spatiotemporal domain to the spectra-wavevector domain.By incorporating Shannon’s entropy theory into the proposed model,we further discover the corresponding information transition efficiencies and the upper bound of the channel capacity of the spatiotemporal metasurface.The results of harmonic information transitions show great potential in achieving high-capacity versatile information processing systems with spatiotemporal metasurfaces. | Haotian Wu Xin Xin Gao Lei Zhang Guo Dong Bai Qiang Cheng Lianlin Li Tie Jun Cui | 2020 | Light(Science & Applications)2020，9，1： | 1 |
| 14 | Directly wireless communication of human minds via non-invasive brain-computer-metasurface platform显示文摘Brain-computer interfaces(BCIs),invasive or non-invasive,have projected unparalleled vision and promise for assisting patients in need to better their interaction with the surroundings.Inspired by the BCI-based rehabilitation technologies for nerve-system impairments and amputation,we propose an electromagnetic brain-computer-metasurface(EBCM)paradigm,regulated by human’s cognition by brain signals directly and non-invasively.We experimentally show that our EBCM platform can translate human’s mind from evoked potentials of P300-based electroencephalography to digital coding information in the electromagnetic domain non-invasively,which can be further processed and transported by an information metasurface in automated and wireless fashions.Directly wireless communications of the human minds are performed between two EBCM operators with accurate text transmissions.Moreover,several other proof-of-concept mind-control schemes are presented using the same EBCM platform,exhibiting flexibly-customized capabilities of information processing and synthesis like visual-beam scanning,wave modulations,and pattern encoding. | Qian Ma Wei Gao Qiang Xiao Lingsong Ding Tianyi Gao Yajun Zhou Xinxin Gao Tao Yan Che Liu Ze Gu Xianghong Kong Qammer HAbbasi Lianlin Li Cheng‑Wei Qiu Yuanqing Li Tie Jun Cui | 2022 | eLight2022，2，1： | 1 |
| 15 | A Novel Autofo cusing Approach for Real-Time Through Wall Imaging Under Unknown Wall Characteristics显示文摘 | Li Lianlin Zhang Wenji Li Fang | 2010 | IEEE Transon Geoscience and Remote Sensing2010，48，1： | 1 |
| 16 | Solution of time-domain Maxwell equation with PML by using modified Laguerre polynomials显示文摘In this work, a stable numerical algorithm proposed by Chung et al. for the time-domain Maxwell equations is generalized. The time-domain Maxwell equations are solved by expressing the transient behaviors in terms of the modified Laguerre polynomials, and then the original equations of the initial value and boundary value can be transformed into a series of problems independent of the time variable. In this case the method of finite difference (FD), the finite element method (FEM), the method of moment (MoM), etc. or the combination of these methods can be used to solve the problems. Finally, a numerical model is provided for the scattering problem with perfect matched layer (PML) by using FD. The comparison between the results of the proposed method and FDTD is presented to verify the proposed new method. | LI LianLin LI Fang | 2008 | Science in China(Series F)2008，51，5： | 0 |
| 17 | Intelligent indoor metasurface robotics显示文摘Intelligent indoor robotics is expected to rapidly gain importance in crucial areas of our modern society such as at-home health care and factories.Yet,existing mobile robots are limited in their ability to perceive and respond to dynamically evolving complex indoor environments because of their inherently limited sensing and computing resources that are,moreover,traded off against their cruise time and payload.To address these formidable challenges,here we propose intelligent indoor metasurface robotics(I2MR),where all sensing and computing are relegated to a centralized robotic brain endowed with microwave perception;and I2MR’s limbs(motorized vehicles,airborne drones,etc.)merely execute the wirelessly received instructions from the brain.The key aspect of our concept is the centralized use of a computation-enabled programmable metasurface that can flexibly mold microwave propagation in the indoor wireless environment,including a sensing and localization modality based on configurational diversity and a communication modality to establish a preferential high-capacity wireless link between the I2MR’s brain and limbs.The metasurface-enhanced microwave perception is capable of realizing low-latency and high-resolution three-dimensional imaging of humans,even around corners and behind thick concrete walls,which is the basis for action decisions of the I2MR’s brain.I2MR is thus endowed with real-time and full-context awareness of its operating indoor environment.We implement,experimentally,a proof-of-principle demonstration at∼2.4 GHz,in which I2MR provides health-care assistance to a human inhabitant.The presented strategy opens a new avenue for the conception of smart and wirelessly networked indoor robotics. | Hanting Zhao Shengguo Hu Hongrui Zhang Zhuo Wang Hao Dong Philipp del Hougne Tie Jun Cui Lianlin Li | 2023 | National Science Review2023，10，8： | 0 |
| 18 | In-situ manipulation of wireless link with reinforcement-learningdriven programmable metasurface in indoor environment显示文摘It is of great importance to control flexibly wireless links in the modern society,especially with the advent of the Internet of Things(IoT),fifth-generation communication(5G),and beyond.Recently,we have witnessed that programmable metasurface(PM)or reconfigurable intelligent surface(RIS)has become a key enabling technology for manipulating flexibly the wireless link;however,one fundamental but challenging issue is to online design the PM's control sequence in a complicated wireless environment,such as the real-world indoor environment.Here,we propose a reinforcement learning(RL)approach to online control of the PM and thus in-situ improve the quality of the underline wireless link.We designed an inexpensive one-bit PM working at around 2.442 GHz and developed associated RL algorithms,and demonstrated experimentally that it is capable of enhancing the quality of commodity wireless link by a factor of about 10 dB and beyond in multiple scenarios,even if the wireless transmitter is in the glancing angle of the PM in the realworld indoor environment.Moreover,we also prove that our RL algorithm can be extended to improve the wireless signals of receivers in dual-receiver scenario.We faithfully expect that the presented technique could hold important potentials in future wireless communication,smart homes,and many other fields. | Jiawen Xu Rong Zhang Jie Ma Hanting Zhao Lianlin Li | 2023 | Journal of Information and Intelligence2023，1，3： | 0 |
| 19 | An auto-focus algorithm for imaging of objects under a lossy earth from multi-frequency and multi-monostatic data显示文摘The problem of auto-focusing imaging of 2D dielectric objects imbedded in a lossy earth is considered.Under Born approximation,the half-space spectrum Green's function is employed to formulate the half-space imaging algorithm from multi-frequency and multi-monostatic data.Hence the fast Fourier transform can be used to achieve real-time imaging in a very short computing time.Since the proposed algorithm has avoided the time-consuming regularization of a large-scale ill-posed matrix,the computing time can be greatly cut down.Inspired by the principle of time reversed imaging and the minimum entropy criterion,an auto-focusing imaging algorithm is presented to remove the image degradation caused by estimated error of the unknown dielectric parameters of the earth.Numerical results have shown that the proposed algorithm can provide good quality focused images for both low-contrast and high-contrast targets in a short computing time despite the inaccurate estimation of the earth electric parameters.The proposed algorithm can be extended to three-dimensional case naturally. | LIU YanLi LI LianLin LI Fang | 2010 | Science China(Information Sciences)2010，53，9： | 0 |
| 20 | Absorption of electromagnetic waves by the dust particles in a plasma显示文摘Absorption of electromagnetic waves by the dust particles in a plasma has been studied based on a Mie-Debye scattering mode. The longitudinal field of the Debye scattering has been derived and the wave energy loss from it has been calculated. It is shown that the lower the temperature of the plasma is and the higher the density of the plasma is, the larger the absorption cross section will be due to the longitudinal scattering. For the low frequency waves the electromagnetic waves scattered in a dusty plasma are mainly in the form of Debye scattering. In this case the energy loss due to the longitudinal scattering will affect the wave propagation seriously. | LI Fang LI Lianlin SUI Qiang | 2004 | Science China(Technological Sciences)2004，47，4： | 0 |
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