摘要
电磁超材料是由亚波长单元周期或非周期地排列而组成的人工电磁结构,可通过设计结构单元及其排布自由地控制电磁波,是信息领域的研究热点之一.本文介绍了东南大学毫米波国家重点实验室从事电磁超材料研究的历史和最新进展,主要分为3个发展阶段.第1阶段发展了等效媒质超材料,提出了超材料结构的等效媒质一般性理论,实验验证了宽带地面隐身衣、电磁黑洞、电磁幻觉及各向异性零折射率等奇特物理现象及功能器件,并在超材料变换光学透镜、平板透镜天线,以及宽带电磁隐身表面等方面获得了应用.第2阶段开拓了基于人工表面等离激元(surface plasmon polariton,SPP)传输线的微波领域新方向,提出一种超薄、低损耗、条带式的SPP传输线,能在共形曲面上传输无畸变的SPP波;基于此,研制了一系列微波SPP无源器件、SPP放大器和倍频器,以及SPP天线,构建了首个全SPP无线通信射频收发系统,在间距为深亚波长的两个通道上实现了两个独立视频无干扰的超视距传输.第3阶段创建了信息超材料新体系,提出用数字编码表征超材料的新思想,通过控制不同的数字编码序列实时地调控电磁波,实现了超材料的现场可编程功能;提出在信息超材料的物理平台上进行信息熵操作及相关的数字卷积定理和加法定理,在物理空间上构筑起数字空间,实现了对电磁波和数字信息的同时调控;基于此研制了新架构的微波成像系统、无线通信系统和智能感知系统.
Electromagnetic metamaterials are periodic or nonperiodic artificial structures comprising basic elements in subwavelength scales.They can be used to control electromagnetic waves by designing the basic elements and their spatial arrangements.Metamaterial has been a research hotspot in physical and information sciences.In this review,I present the history and main progresses achieved in metamaterial studies conducted in the State Key Laboratory of Millimeter Waves at Southeast University,which were performed in three stages.In the first stage,we improved the developments in effective-medium metamaterials.In particular,we proposed a general theory to accurately describe the effective permittivity and permeability of metamaterials.Based on the general theory,we designed and realized a three-dimensional(3D)wideband ground-plane invisibility cloak,free-space electrostatic invisibility cloak,electromagnetic black hole,electromagnetic illusions,and radially anisotropic zero-index metamaterial for omni-directional radiations and nearly perfect power combinations of source arrays.Moreover,we undertook significant efforts in engineering applications of microwave metamaterials,such as broadband and low-loss 3D transformation-optic lens for wide-angle scanning,3D planar gradient-index lens for high-gain radiations,and random metasurfaces to reduce radar cross sections.In the second stage,we opened up a new direction of plasmonic metamaterials from the viewpoint of microwave transmission lines.We proposed an ultrathin,narrow,and flexible corrugated metallic strip to guide spoof surface plasmon polaritons(SPPs)with small bending and radiation losses,based on which we designed and realized a series of passive SPP devices(such as power divider,coupler,filter,and resonator),active SPP devices(such as amplifier and duplexer)and SPP antennas in the microwave bands.We demonstrated a significant feature of the ultrathin SPP transmission line in overcoming challenges of signal integrity existing in the traditional integrated devices and circuits.We built up a full-SPP wireless communication system with unique properties to remotely transmit two movies in two deepsubwavelength-distance channels exhibiting excellent performance.In the third stage,we established a new area of metamaterial-information metamaterial.We proposed to describe the metamaterial using digital coding from the information science viewpoint,which directly resulted in a new kind of metamaterial-digital coding metamaterial.We theoretically and experimentally illustrated that the digital coding metamaterials comprising digital units can be controlled using different coding sequences to achieve different functions.When the digital state of the coding unit was controlled using a field programmable gate array(FPGA),we realized a field programmable metamaterial that can manipulate electromagnetic waves in real time and generate numerous different functions using a single piece of hardware.The digital coding metamaterial provides a platform to establish a digital space on the physical space and enriches the methodology and theory of metamaterials.We proposed measuring the information capacity of metamaterials using Shannon entropy and presented the convolution and addition theorems on metamaterial platforms,which can be used to simultaneously control the physical properties and digital information.Based on information metamaterials,we established new-architecture microwave imaging systems,wireless communication systems,and other intelligent information systems.
作者
崔铁军
Tiejun CUI(State Key Laboratory of Millimeter Waves,School of Information Science and Engineering,Southeast University,Nanjing 210096,China;Institute of Electromagnetic-Space Science and Technology,Southeast University,Nanjing 210096,China)
出处
《中国科学：信息科学》
CSCD
北大核心
2020年第10期1427-1461,共35页
Scientia Sinica(Informationis)
基金
国家重点研发计划(批准号:2017YFA0700201,2017YFA0700202,2017YFA0700203)
国家自然科学基金(批准号:61631007,61731010,61735010)
国家自然科学基金国际(地区)合作与交流项目(批准号:61761136007)
111计划(批准号:111-2-05)资助项目。
关键词
电磁超材料
等效媒质
表面等离激元
数字编码
现场可编程
信息超材料
信息系统
electromagnetic metamaterial
effective-medium model
surface plasmon polaritons
digital coding metamaterial
field programmable
information metamaterial
information system
