Electrically controllable soft optical cloak based on gold nanorod fluids with epsilon-near-zero characteristic.

We propose an electrically controllable soft optical cloak based on a fluid system containing gold nanorods, which can be transformed from isotropic to anisotropic epsilon-near-zero (ENZ) state at a certain incident optical frequency due to the orientation of gold nanorods under an external electric field stimulus. Both effective medium theory and 3D finite element simulation demonstrate that, at the ENZ point, the scattering from arbitrary-shaped objects can be nearly perfect suppressed. The loss and aspect ratio of gold nanorods have an effect on the ENZ point and scattering suppression behavior. When different aspect ratio of gold nanorods is employed, the fluid has multi ENZ points and exhibits perfect suppression of scattering from objects at multiple incident optical frequencies. Because the orientation of gold nanorods depends on the strength of applied external electric field, the permittivity of fluid can be adjusted by external electric field and, as a result, the ENZ state and scattering suppression of objects can be controlled. The flexible, controllable, and multi-frequency responsive characteristics make the optical cloak possess potential use in soft smart metamaterial devices.

[1]  N. Engheta,et al.  Infrared and optical invisibility cloak with plasmonic implants based on scattering cancellation , 2008 .

[2]  Xiaopeng Zhao,et al.  Electrically tunable negative refraction in core/shell-structured nanorod fluids. , 2014, Soft matter.

[3]  Qiang Cheng,et al.  Experimental demonstration of electromagnetic tunneling through an epsilon-near-zero metamaterial at microwave frequencies. , 2008, Physical review letters.

[4]  Jin Au Kong,et al.  Robust method to retrieve the constitutive effective parameters of metamaterials. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[5]  Huanyang Chen,et al.  Goos-Hänchen effect in epsilon-near-zero metamaterials , 2015, Scientific Reports.

[6]  M. Premaratne,et al.  Hiding inside an arbitrarily shaped metal pit using homogeneous metamaterials , 2012 .

[7]  Xiaodong Yang,et al.  Infrared perfect absorber based on nanowire metamaterial cavities. , 2012, Optics letters.

[8]  Ying Wu,et al.  Effective medium theory for anisotropic metamaterials , 2014, Scientific Reports.

[9]  Daniel J. Klingenberg,et al.  Electrorheology : mechanisms and models , 1996 .

[10]  Andrea Alù,et al.  Experimental verification of epsilon-near-zero metamaterial coupling and energy squeezing using a microwave waveguide. , 2008, Physical review letters.

[11]  L. C. Davis.  The metal-particle/insulating oil system : an ideal electrorheological fluid , 1993 .

[12]  Jie Gao,et al.  Nonlocal effective medium approximation for metallic nanorod metamaterials , 2015 .

[13]  Hongsheng Chen,et al.  Electromagnetic wave interactions with a metamaterial cloak. , 2007, Physical review letters.

[14]  R. J. Bell,et al.  Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared. , 1983, Applied optics.

[15]  F. Lederer,et al.  A self-assembled three-dimensional cloak in the visible , 2013, Scientific Reports.

[16]  Alessandro Salandrino,et al.  Epsilon-near-zero metamaterials and electromagnetic sources: Tailoring the radiation phase pattern , 2007 .

[17]  A. Alú,et al.  Optical Scattering Cancellation through Arrays of Plasmonic Nanoparticles: A Review , 2015 .

[18]  F. Lederer,et al.  Cloaking dielectric spherical objects by a shell of metallic nanoparticles , 2011, 1102.3650.

[19]  F. Bilotti,et al.  Possible implementation of epsilon-near-zero metamaterials working at optical frequencies , 2012 .

[20]  P. Sheng,et al.  Transformation optics and metamaterials. , 2010, Nature materials.

[21]  R J Pollard,et al.  Manipulating polarization of light with ultrathin epsilon-near-zero metamaterials. , 2013, Optics express.

[22]  O. Levy.  Dielectric response and electro-optical effects in suspensions of anisotropic particles. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[23]  Willie J Padilla,et al.  Perfect metamaterial absorber. , 2008, Physical review letters.

[24]  T. Mayer,et al.  Formation and frequency response of two-dimensional nanowire lattices in an applied electric field. , 2015, Langmuir : the ACS journal of surfaces and colloids.

[25]  F. Bilotti,et al.  Optical cloaking of cylindrical objects by using covers made of core-shell nanoparticles. , 2011, Optics letters.

[26]  J. Pendry,et al.  Three-Dimensional Invisibility Cloak at Optical Wavelengths , 2010, Science.

[27]  David R. Smith,et al.  Metamaterial Electromagnetic Cloak at Microwave Frequencies , 2006, Science.

[28]  J. Parsons,et al.  Experimental realization of an epsilon-near-zero metamaterial at visible wavelengths , 2013, Nature Photonics.

[29]  M. Dijkstra,et al.  Phase diagram of dipolar hard and soft spheres: manipulation of colloidal crystal structures by an external field. , 2005, Physical review letters.

[30]  Bo Hou,et al.  Arbitrary control of electromagnetic flux in inhomogeneous anisotropic media with near-zero index. , 2014, Physical review letters.

[31]  Tatsuhiro Takahashi,et al.  Aligning vapor-grown carbon fibers in polydimethylsiloxane using dc electric or magnetic field , 2006 .

[32]  Andrea Alù,et al.  Optical invisibility through metasurfaces made of plasmonic nanoparticles , 2015 .

[33]  B. M. I. van der Zande,et al.  Alignment of rod-shaped gold particles by electric fields , 1999 .

[34]  A. Sihvola.  Mixing Rules with Complex Dielectric Coefficients , 2000 .

[35]  Richard W Ziolkowski,et al.  Propagation in and scattering from a matched metamaterial having a zero index of refraction. , 2004, Physical review. E, Statistical, nonlinear, and soft matter physics.

[36]  F. Lederer,et al.  Scattering cancellation of the magnetic dipole field from macroscopic spheres. , 2012, Optics express.

[37]  David R. Smith,et al.  A full-parameter unidirectional metamaterial cloak for microwaves. , 2013, Nature materials.

[38]  A. Zayats,et al.  Scattering suppression from arbitrary objects in spatially dispersive layered metamaterials , 2015, 1501.00392.

[39]  Nonlocal homogenization model for a periodic array of epsilon-negative rods. , 2006, Physical review. E, Statistical, nonlinear, and soft matter physics.

[40]  M. Wegener,et al.  Magnetic Response of Metamaterials at 100 Terahertz , 2004, Science.

[41]  Optical nonlocalities and additional waves in epsilon-near-zero metamaterials. , 2009 .

[42]  Shulin Sun,et al.  Gradient-index meta-surfaces as a bridge linking propagating waves and surface waves. , 2012, Nature materials.

[43]  Yuri S. Kivshar,et al.  Green function for hyperbolic media , 2012, 1206.7076.

[44]  David R. Smith,et al.  Broadband Ground-Plane Cloak , 2009, Science.