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手性超材料圆极化波吸收特性研究进展

2019,Vol.33,No.2

www.mater-rep.com

liminhua@nbu.edu.cnDOI:10.11896/cldb.201903017 基金项目:国家自然科学基金(61501269);浙江省自然科学基金(LQ16F010002);宁波市自然科学基金(2014A610144) ThisworkwasfinanciallysupportedbytheNationalNaturalScienceFoundationofChina(61501269),theNaturalScienceFoundationofZhejiang(LQ16F010002),theNaturalScienceFoundationofNingbo(2014A610144).

手性超材料圆极化波吸收特性研究进展

汪丽丽,宋 健,梁加南,

李敏华

宁波大学信息科学与工程学院,宁波315211

基于亚波长单元结构的人工电磁超材料具有优异的电磁/光学特性,如负折射率二超分辨率以及极化转化等,使得超材料研究成为近年量子通信二纳米光学二材料科学二能源探测等领域的前沿研究方向,其中以手性超材料的研究尤为突出三手性超材料是指与其镜像不具有几何对称性,且不可通过旋转或平移等任意操作使其与镜像重合的一种新型电磁超材料三超材料的深入研究,极大地丰富了手性结构的建模,为许多隐晦物理现象和理论分析的研究提供了更多有效的方法三手性超材料所具备的超强光学活性二圆二色性以及不对称传输等独特的电磁/光学特性,也为电磁学二物理学二材料科学二光学二声学二纳米科学以及信息科学等领域提供了全新的研究方向三

手性是手性分子的一种固有特征,也是生命体征的一种表现,在有机世界中普遍存在,诸如蛋白质二DNA二糖分子二病毒二氨基酸和液晶体等分子三然而在自然界中,手性结构十分有限,有关建模和理论分析仅停留在原始结构的表征三目前,手性超材料的研究正逐步从微波段扩展至太赫兹二红外波段,甚至光波段三

基于手性微结构的电磁超材料的实现很大程度上取决于单元结构尺寸和周期阵列排布,因此吸收带宽仍然局限于较窄的频率范围,且对左旋圆极化波(LCP)和右旋圆极化波(RCP)的识别(选择性吸收)能力较弱三随着对手性超材料的进一步研究,微波频段的差异化吸收率逐步提高到90%以上,但在高频段差异化的吸收率仍然较低三此外,随着微纳技术和纳米技术的发展,利用包括半导体材料二相变材料二高电阻/电感/电容薄膜二石墨烯在内的新型功能材料,以及结合集总元件的匹配电路控制,为实现红外二可见光波段的吸波器提供了研究空间三

本文介绍了手性超材料对圆极化波的吸收原理,着重阐述了内在手性结构二外在手性结构以及与包括半导体材料二石墨烯等其他新型功能材料相结合的手性超材料吸收光谱的研究进展三这种基于人工电磁微结构的手性吸波特性可应用于极化转化器二电磁能量收集器二红外成像等电磁/光学器件设计中三

关键词 手性超材料 左旋圆极化波 右旋圆极化波 手性吸收 圆二色性

中图分类号:TB34 文献标识码:A

ResearchProgressoftheAbsorptionCharacteristicsofCircularPolarizationWaveinChiral Metamaterials

WANGLili,SONGJian,LIANGJianan,LI

MinhuaFacultyofElectricalEngineeringandComputerScience,NingboUniversity,Ningbo315211Artificial electromagneticmetamaterialsbasedonthesubwavelengthunitsstructurehaveexcellentelectromagnetic/optical properties,suchasnegativerefractiveindex,super-resolutionandpolarizationconversion,makingthemtobetheleadingfieldintheareasofquantumcommu-nication,nano-optics,material science,energyexplorationandothersinrecentyears.Amongthem,thestudyofchiral metamaterialsisparticu-larlyprominent.Chiral metamaterialsrefertoanewtypeofelectromagneticmetamaterial whichhavenogeometricsymmetryandcan tbeover-lappedwiththeirmirrorimagebyrotationortranslationorotheroperations.Thefurtherinvestigationsofmetamaterialsdrasticallyenrichthemode-lingofchiral structures,andprovidemoreeffectivemethodsfortheresearchofmanyobscurephysical phenomenasandtheoretical analysis.Theuniqueelectromagnetic/optical propertiesofchiral metamaterials,includingultra-strongoptical activity,circulardichroismandasymmetrictrans-mission,offerafire-newresearchdirectionforelectromagnetic,physics,materialsscience,optics,acoustics,nanoscienceandinformationscience,etc. Chiralityisconsideredtobeaninherentfeatureofchiral moleculesandamanifestationofvital signsthatareubiquitousintheorganicworld,suchasproteins,DNA,sugarmolecules,viruses,aminoacidsandliquidcrystals.However,thechiral structureisextremelylimitedinnature,andtherelatedmodelingandtheoretical analysismerelystayatthecharacterizationoftheoriginal structure.Atpresent,theresearchofchiral metamaterialsisgraduallyexpandingfrommicrowavesegmenttotheterahertz,infraredband,andevenlightwaveband. Sincetherealizationofelectromagneticmetamaterialsbasedonchiral microstructureshighlyliesonthesizeofthecell structureandthear-rangementofperiodicarrays,thustheabsorptionbandwidthisstill limitedinanarrowerfrequencyrange,andtheabilityofrecognizing(selectiveabsorption)theleft-handedcircularpolarizedwave(LCP)andright-handedcircularpolarizedwave(RCP)isrelativelyweakaswell.Withthefurtherresearchonthechiral metamaterials,thedifferential absorptivityofmicrowavefrequencybandisgraduallyincreasedover90%,whileinhighfrequencybanditisstill low.Inaddition,withthedevelopmentofmicro-nanotechnologyandnanotechnology,theutilizationofnewfunctio-nal materials,includingsemiconductormaterials,phasechangematerials,highresistance/inductance/capacitancethinfilmsandgraphene,andmatchingcircuitscombinedwithlumpedelementsprovidearesearchspaceforachievinginfraredandvisiblewavebandabsorbers. Thispaperintroducestheprincipleofabsorptionofcircularpolarizedwavesbychiral metamaterials,anddetailedlyexpoundtheresearchpro-gressintheabsorptionspectraofchiral metamaterialsofintrinsicchiral structure,theexternal extrinsicchiral structureandothernewfunctional materials,includingsemiconductormaterials,graphene,etc.Thechiral absorptioncharacteristicsbasedonartificial electromagneticmicrostruc-turesareavailableinthedesignofelectromagnetic/optical devicessuchaspolarizationconverter,electromagneticenergycollector,infraredima-gingandsoon.

Keywords chiral metamaterial,left-handedcircularpolarizedwave,right-handedcircularpolarizedwave,chiral absorption,circulardichroism0 引言

电磁超材料(Metamaterials,MMs)[1-2]是由人为设计的亚波长单元构成的人工电磁微结构在空间中按照一定周期性或非周期性构造而成三与自然界中材料不同,电磁超材料存在很多奇异特性,如逆古斯-汉欣位移二逆多普勒效应二逆斯奈005万方数据

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