Negative index material (from metamaterial to liquid crystals)

Outline of research workWhat is NIM?What is the applications of NIM?How to achieve NIMDiscussion and ConclusionFuture work3

What is NIM?airCondition for NIM:airDouble-negative NIM:4

Negative refraction‣Snell’s lawWhat is NIM?‣Boundary condition:tangential components of E & H areconstant.5

Negative refraction‣Snell’s lawWhat is NIM?‣Boundary condition:tangential components of E & H areconstant.6

Negative refraction‣Snell’s lawWhat is NIM?‣Boundary condition:tangential components of E & H areconstant.7

What is applications of NIM?1. Superlens & hyperlens• Sub-wavelength imaging;• Memory storageDNAobjectDNAobject2. Optical transformation• Optical cloaking• Light concentrator8

How to achieve NIM?Ordinary metamaterial– Electrical metamaterialsElectric polarizability α

How to achieve NIM?Ordinary metamaterial– Electrical metamaterialsRelative dielectric constant:10

How to achieve NIM?Ordinary metamaterial– Electrical metamaterialsRelative dielectric constant:For metal,11

How to achieve NIM?Ordinary metamaterial– Magnetic metamaterials(Split-ring resonators)12

How to achieve NIM?Ordinary metamaterial– Magnetic metamaterials(Split-ring resonators)13

How to achieve NIM?Ordinary metamaterial( )kHESRRHkEFishnetNature 455. 2008.14

Chiral metamaterialHow to achieve NIM?Eigenvalues:15E.Plum etc, “Metamaterial with negative index due to chirality”, Physical Review B. 79 (2009).

Metamaterial with LC?How to achieve NIM?‣Structured metamaterial has negative refractive index up tovisible frequency range. The manufacture technique iswell established;‣LC is a anisotropic media, and can be reconfiguredelectrically.metamaterialLC?Electricallytunable NIM16

Metamaterial with LC!‣Nematic LC-NIM:How to achieve NIM?Liquid crystalshellcoreStructure of the nanosphereDispersing metallic particles in the LC hostI.C.Khoo’s group, Penn. State U. , Opt. Lett. 2006.17

Metamaterial with LC!‣Nematic LC-NIM:How to achieve NIM?Liquid crystalshellcoreWhere,N—volume density of particle;18

Metamaterial with LC!‣Chiral LC-NIM:How to achieve NIM?Nanoparticlesattached to chiralcomponents lowerdielectric permittivityChiral liquid crystal doped with nanoparticlesDr. Prasad group, U. SUNY at Buffalo, Opt. Exp. 2007.19

Conclusion‣Negative refractive index can be achieved by3-D nano-structured metamaterials (SRR, Fishnetand chiral structure);‣Traditional nematic LC with nanoparticles(nanostructures) can create tunable negativerefractive index;‣Chiral LC with nanoparticles can also offer excitingnegative refractive index.20

Future interesting work‣ Simulation on optical cloakingdispersed in liquid crystal.with nanorods‣ Dispersing nanorods in nematic LC by using polymerstablization technique to form certain nanorodsdispersion pattern.‣Dispersing nanorods in chiral LC by using polymerstablization technique to achieve NIM.21

Optical cloaking:(Computer simulation)Extended exampleV.M.Shalaev’s group, Nature 224-227. 2007.22

Optical cloaking:(Computer simulation)Extended exampleV.M.Shalaev’s group, Nature 224-227. 2007.23

Optical cloaking:(experiment)Extended exampleOleg D.Lavrentovich’s group, Applied Physics Lett., 2009.24

Optical cloaking:(experiment)Extended exampleCloak areaOleg D.Lavrentovich’s group, Applied Physics Lett., 2009.25

Thanks for your attentionand questions!26

Optical cloaking 2:(experiment)Extended exampleXiang Zhang’s group, Nature. Mat. 568-571, 2009.27

Optical cloaking 2:(experiment)Extended exampleXiang Zhang’s group, Nature. Mat. 568-571, 2009.28

Electromagnetic Material PropertiesThe electromagnetic response of a material is defined by itselectromagnetic properties: permittivity ε and permeability µµε no transmission0, µ < 0= −εµ0Negative IndexMaterialsConventionalMaterialsε >n0, µ > 0= +εµSplit Ringsε > 0 , µ

How to achieve NIM?Ordinary metamaterial(Split-ring resonators)30

Superlens & hyperlens31

How to achieve NIM?Ordinary metamaterial– Electrical metamaterials32

How to achieve NIM?Ordinary metamaterial– Magnetic metamaterials(Split-ring resonators)33