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Absorption of electromagnetic waves by the dust particles in a plasma

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Science China(Technological Sciences) 2004年第4期47卷 461-469页

作者： li Fang li lianlin SUI Qiang Institute of Electronics Chinese Academy of Sciences Beijing 100080 China Institute of Electronics Chinese Academy of Sciences Beijing 100080 China Institute of Electronics Chinese Academy of Sciences Beijing 100080 China

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.

关键词： dusty plasma, Mie-Debye scatter, absorption cross section, total section.

Inverse scattering from phaseless data in the freespace

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Science in China(Series F) 2009年第8期52卷 1389-1398页

作者： ZHANG WenJi li lianlin li Fang Institute of Electronics Chinese Academy of Sciences Beijing 100190 China Graduate School of Chinese Academy of Sciences Beijing 100049 China

In this paper a new approach for microwave imaging of unknown objects embedded in the freespace from phaseless data is presented. Firstly a cost functional is constructed by using the measured amplitude of the total field, which is the norm of the discrepancy between the measured amplitude and the calculated one. Then both the amplitude and phase of the scattered field are retrieved by minimizing the above cost functional. Finally, the geometrical and electrical parameters are reconstructed by using the retrieved scattered field. The phase retrieval process can be achieved in a very short time without adding any burden to the whole inverse scattering problem. The equivalent current density is introduced to reduce the nonlinearity of the inverse problem. The reconstruction of the non-radiating component of the equivalent current density improves the imaging quality. Experimental results are presented for the first time to show the feasibility of inverse scattering from phaseless data. The experimental results also show the validity and stability of the proposed method.

关键词： electromagnetic inverse scattering phaseless imaging phase retrieval inverse source experimental validation

DESIGN OF SPARSE ARRAY FOR MAD IMAGING BASED ON MAXIMIZING INFORMATION CAPACITY

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Journal of Electronics(China) 2013年第5期30卷 476-482页

作者： li lianlin B.Jafarpour Department of Electronics Engineering and Computer Science Peking University Department of Petroleum Engineering University of Southern CaliforniaCA 90089 USA

In past years,growing efforts have been made to the rapid interpretation of magnetic field data acquired by a sparse synthetic or real magnetic sensor *** appealing requirement on such sparse array arranged within a specified survey region is that to make the number of sensor elements as small as possible,meanwhile without deteriorating imaging *** this end,we propose a novel methodology of arranging sensors in an optimal manner,exploring the concept of information capacity developed originally in the communication *** proposed scheme reduces mathematically the design of a sparse sensor array into solving a combinatorial optimization problem,which can be resolved efficiently using widely adopted Simultaneous Perturbation and Statistical Algorithm(SPSA).Three sets of numerical examples of designing optimal sensor array are provided to demonstrate the performance of proposed methodology.

关键词： Sparse array Magnetic vector and tensor fields Maximizing information capacity Simultaneous Perturbation and Statistical Algorithm(SPSA) Geophysics exploration

Smart metasurface with self-adaptively reprogrammable functions

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light(Science & Applications) 2019年第1期8卷 266-277页

作者： Qian Ma Guo Dong Bai Hong Bo Jing Cheng Yang lianlin li Tie Jun Cui State Key Laboratory of Millimeter Wave Southeast University210096 NanjingChina Jiangsu Cyber-Space Science&Technology Co. Ltd.12 Mozhou East Road211111 NanjingChina State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking University100871 BeijingChina

Intelligence at either the material or metamaterial level is a goal that researchers have been *** passive to active,metasurfaces have been developed to be programmable to dynamically and arbitrarily manipulate electromagnetic(EM)***,the programmable metasurfaces require manual control to switch among different ***,we put forth a smart metasurface that has self-adaptively reprogrammable functionalities without human *** 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 *** 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 *** develop an online feedback algorithm as the control software to make the smart metasurface achieve single-beam and multibeam steering and other dynamic reactions *** proposed metasurface is extendable to other physical sensors to detect the humidity,temperature,illuminating light,and so *** strategy will open up a new avenue for future unmanned devices that are consistent with the ambient environment.

关键词： surface ambient adjust

Harmonic information transitions of spatiotemporal metasurfaces

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light(Science & Applications) 2020年第1期9卷 58-70页

作者： Haotian Wu Xin Xin Gao Lei Zhang Guo Dong Bai Qiang Cheng lianlin li Tie Jun Cui State Key Laboratory of Millimetre Waves Southeast University210096 NanjingChina Institute of Electromagnetic Space Southeast University210096 NanjingChina State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking University100871 BeijingChina

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 *** 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 *** 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 *** 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 *** results of harmonic information transitions show great potential in achieving high-capacity versatile information processing systems with spatiotemporal metasurfaces.

关键词： surface transitions surfaces

Information theory of metasurfaces

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National Science Review 2020年第3期7卷 561-571页

作者： Haotian Wu Guo Dong Bai Shuo liu lianlin li Xiang Wan Qiang Cheng Tie Jun Cui State Key Laboratory of Millimeter Waves Southeast University School of Physics and Astronomy University of Birmingham State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronics Peking University

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 aperture model 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. The proposed 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, whereγ is 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.

关键词： metasurfaces differential entropy radiation information bounds maximum orthogonal radiation patterns information invariance

One-bit quantization is good for programmable coding metasurfaces

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Science China(Information Sciences) 2022年第7期65卷 225-239页

作者： Ya SHUANG Hanting ZHAO Menglin WEI Qiang CHENG Shi JIN Tiejun CUI Philipp DEL HOUGNE lianlin li State Key Laboratory of Advanced Optical Communication Systems and Networks Department of ElectronicsPeking University Institute of Electromagnetic Space Southeast University State Key Laboratory of Millimeter Waves Southeast University Pazhou Laboratory University of Rennes

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.

关键词： metasurfaces metamaterials information capacity signal representation one-bit coding metasurface

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Intelligent indoor metasurface robotics

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National Science Review 2023年第8期10卷 20-32页

作者： Hanting Zhao Shengguo Hu Hongrui Zhang Zhuo Wang Hao Dong Philipp del Hougne Tie Jun Cui lianlin li State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Peking University Center on Frontiers of Computing Studies School of Computer Science Peking University The French National Centre for Scientific Research(CNRS) University of Rennes 4. State Key Laboratory of Millimeter WavesSoutheast University

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.

关键词： intelligent metasurfaces intelligent robotics edge devices IoT 6G

Intelligent metasurfaces:control,communication and computing

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elight 2022年第1期2卷 75-98页

作者： lianlin li Hanting Zhao Che liu Long li Tie Jun Cui State Key Laboratory of Advanced Optical Communication Systems and Networks School of ElectronicsPeking UniversityBeijing 100871China Key Laboratory of High‑Speed Circuit Design and EMC of Ministry of Education School of Electronic EngineeringXidian UniversityXi’an 710071China State Key Laboratory of Millimeter Waves Southeast UniversityNanjing 210096China

Controlling electromagnetic waves and information simultaneously by information metasurfaces is of central importance in modern *** 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 ***,we review the recent progress of intelligent metasurfaces in wave-information-matter controls by providing the historical background and underlying physical *** we explore the application of intelligent metasurfaces in developing novel wireless communication architectures,with particular emphasis on metasurface-modulated backscatter wireless *** also explore the wave-based computing by using the intelligent metasurfaces,focusing on the emerging research direction in intelligent ***,we comment on the challenges and highlight the potential routes for the further developments of the intelligent metasurfaces for controls,communications and computing.

关键词： communication computing intelligent