材料物理_超材料物理

1、会计学1材料物理材料物理_超材料物理超材料物理V. G. Veselago, The electrodynamics of substances with simultaneously negative values of e and , Sov. Phys. Usp., 1968, 10: 509514.Science 314(5801): 977-980: Metamaterial Electromagnetic Cloak at Microwave Frequencies Science 2006 312(5781), 1780-1782: Controlling Electromagn

2、etic Fields 在经典电动力学中，介质的电磁性质可以用介电常数和磁导率两个宏观参数来描述。正弦时变电磁场的波动方程（Helmholtz方程）为： 其中2Ek E0 2222r0r0k 2Bk B0 2v自然界中物质的和一般都与电磁波频率有关，并且在 大多数情况下都为正数，此时方程(1)有波动解，电磁波能在其中传播。对于无损耗、各向同性、空间均匀的介质，由Maxwell方程组能推出 可见， 、 、 之间满足右手螺旋关系。kE Hv如果介质的和都小于零，方程(1)有波动解，电磁波能在其中传播。但是 、 、 之间不再满足右手螺旋关系而是满足左手螺旋关系。这种介质就被称为“左手材料左手材料”

3、（Left-Handed Metamaterials)通常的介质就被称为“右手材料” (Right-Handed Materials)kHE kHE kEH 0k E 0k H v如果介质的和两者之间一个为正数而另一个为负数， 则k2 0, 0)左手材料( 0, 0, 0)左手材料( 0, 0, 0)左手材料( 0, 0, 0)左手材料( 0, 0RaysWavevectors k 2 2n = 1 1 1n 0, 10 )( 20, 20, 10 )( 20, 20, 20)右手材料）vkzSkkrkSvkzSkkrkrkSvkzkkv左手材料中krSk2k反射體光源k2k反射体光源左手介質

4、中Sk2k光源2k光源左手材料中S反射体(b)(a)Fig 4. 一般介质与左手材料中的比较：(a) Cerenkov效应；(b) 光压rzi( kkt )evkzSkkrkSvkzSkkrkrkSvkzkkv左手材料中krSk2k反射體光源k2k反射体光源左手介質中Sk2k光源2k光源左手材料中S反射体(b)(a)Fig 4. 一般介质与左手材料中的比较：(a) Cerenkov效应；(b) 光压The permittivity of metal is given by)(1)(2iepeepmne022Plasma frequency:where n is the electron den

5、sity, and me is the electron massDamping factor: 0where is the electric conductivity In the visible region, is negative for most metals. At lower frequencies, permittivity is imaginary.(typically in the UV region)Negative with small loss in low frequencies can be achieved by metallic wire latticePen

6、dry J.B. et al., Phys. Rev. Lett. 76, 4773 (1996) ,22arnneff)/ln(220ranemeffeffeffepmen022,100 . 16mr,100 . 53ma31710675. 5mn! !2.8GHzep)1 . 0(12epepeffilattice constant:radius of wire:Obtaining electric responseDrude ModelE)(1)(2iep-5-4-3-2-101012300.511.52GapChettiar, et all, MRS bulletin Oct 2008

7、Phys. Rev. Lett. 84, 4184 (2000)Obtaining magnetic response iFp20221-3-2-1012301200.511.52Gap iFp20221)(1)(2iepMetamaterials Resonance Properties 1-wp2w2 1-wp2w2- w02J. B. PendryFirst Left-Handed Test StructureUCSD, PRL 84, 4184 (2000)Wires alone0000000UCSD, PRL 84, 4184 (2000)Phys. Rev. Lett. 92, 1

8、17403 (2004):Overcoming the Diffraction Limit with a Planar Left-Handed Transmission-Line Lens Fig 11. Photonic Crystals: (a), (b) Holes-in-dielectric; (c) rods-in-air(c)光子晶体(PC)是由两种或两种以上的电介质材料周期性排列而成的人造材料，排列周期为波长量级，具有光电带隙，可以控制电磁波在其中的传播。在一定条件下，它也可以表现出负折射率的现象。7/24/20097/24/200957Shiv Ashish Kumar Exp

9、erimental verification of negative refractionaLattice constant a=4.794 mmDielectric constant=9.61R/a=0.329Frequency=13.698 GHzsquare lattice E(TM) polarizationBilkent & ISUBand structure, negative refraction and experimental set upBilkent & ISUNegative refraction is achievable in this freque

10、ncy range for certain angles of incidence.Frequency = 13.7 GHz = 21.9 mm17 layers in the x-direction and 21 layers in the y-directionSuperlensing in photonic crystalsFWHM = 0.21 Image PlaneDistance of the source from the PC interface is 0.7 mm ( /30)Subwavelength Resolution in PC based SuperlensThe

11、separation between the two point sources is /3Fig4. Photographe of sample,consisted of square copper split ring resonators and copper wire strips on fiber glass circuit微波波段实验测量装置图频频率率为为的偶极子，其的偶极子，其辐辐射射场场的的电场电场分量可以利用分量可以利用傅立叶傅立叶级级数展开数展开为为如下形式：如下形式：倏逝波衰减很快，无法参与成像，故倏逝波衰减很快，无法参与成像，故传统传统光学透光学透镜镜参与成像的成分参与成像的成分为为故分辨率故分辨率为为1nV. G. Veselago, The electrodynamics of substances with simultaneously negative values of e and , Sov. Phys. Usp., 1968, 10: 509514.Obtaining electric responseDrude ModelE)(1)(2iepChettiar, et all, MRS bulletin Oc