零折射率材料的直观理解1.波长无穷大AE>EAclassofmetamaterialsdesignedwithlowwpermittivityprovidesaplatformfordevelopingoptical devices with unconventional properties0agW3.ENZ中隧穿效应2.等效ENZ材料等相位、场均匀、局域增强-B8>0E<08<0E<0E<08>0~0E>0E>0E>0e>0NaderEngheta,PursuingNear-ZeroResponse.19APRIL2013VOL340SCIENCE,340,286（2013)7
7 零折射率材料的直观理解 1. 波长无穷大 2. 等效ENZ材料 Nader Engheta，Pursuing Near-Zero Response，19 APRIL 2013 VOL 340 SCIENCE，340，286（2013） 3. ENZ中隧穿效应 等相位、场均匀、局域增强
零折射率材料的物理实现大体分为两类1.天然材料2.等效零折射率材料（都叫做等效折射率2.a材料本身的等效2.b传播常数的等效2.c群速度转变的等效重点介绍：epsilon-near-zero,ENz：8
8 零折射率材料的物理实现 大体分为两类 1. 天然材料 2. 等效零折射率材料 (都叫做等效折射率) 2.a 材料本身的等效 2.b 传播常数的等效 2.c 群速度转变的等效 重点介绍: epsilon-near-zero，ENZ
1.天然零折射率材料介电常数的洛伦兹模型和特鲁德模型Re(e)ARe(d)Er,Lorentz=1+x+Z- Im(e)-- Im(e],-w2-io/1+Xq'N11+X+mq'NAErDrude=1+x0e.mw"+irw.Re(n)Re(n)Near-zero-index materialsIm(n)Im(n)aefor photonicsgNNathanielKinsey*,ClaytonDeVaultAlexandraBoltassevaandYmwVladimirM.Shalaev2.3*NATUREREVIEWSIMATERIALS1742|DECEMBER2019/VOLUME49
9 1. 天然零折射率材料 介电常数的洛伦兹模型和特鲁德模型
UltravioletInfraredVisibleNearinfraredBiSbTeSeENZANiSi928NiSi1eeTiSiTO.N.$4口Si.2910.TINE一口4口SL207品BibTee中InSbieAZOEPdGeisAuis?Si:InAi4口ZrN"(a?思Ge:GaNseSiGaAs"s8Al:Ag2ZnisOO.6TP1SHINISGapios99.T/20InAsSb8InpanITOM296.SiCM226Sio,0GaAs'sInCdO82OOGZO175AIN20Inpa27Dy:Cdo:%0.1.OSrTiOasOhBN(ey2sOhBN(eyasAPsNZI1001,00010,000Wavelength(nm)OMetalsSemi-metalsPhononicAInterbandDopedsemiconductorsFig.2|Comparisonofexperimentallyrealizedbulkhomogeneouse-near-zeroandnear-zero-indexmaterials.Thevalueoftheimaginarypermittivityeisplottedatthecrossoverwavelength()atwhichtherealpermittivityiszero.Materialswithanimaginarypermittivitysmallerthan2atthecrossoverwavelengthexhibitnear-zero-index(NZl)properties.Thelines connectthedifferentmeasuredvaluesoflm(e)foragivenstaticallytunablematerial and illustratetheirvariabilityENZ,e-near-zero;hBN,hexagonalboronnitride.10文献与上页同
10 文献与上页同
natuireARTICLESphotonicsPUBLISHED.ONLINE:13OCTO8IR2013|DOE:10.1038/NPHOTON.2013.2502.等效零折射率材料Experimental realizationof an epsilon-near-zerometamaterialatvisiblewavelengths2.a材料本身的等效：Ruben Maasi*, James Parsons, Nader Engheta? and Albert Polman用材料的平均折射率来等效8ay=p8m+(1-p)8da10SiN0.3pue-10Aga20-30300500600700400800Wavelength (nm)b5P=20%opue0p=50%-5p=30%-10300400500600700800Wavelength (nm)11
11 2. 等效零折射率材料 2.a 材料本身的等效： 用材料的平均折射率来等效