The possibility of using metamaterial and plasmonic covers to drastically reduce the scattering from an object was recently proposed by our group in 2005. Our approach in the use of plasmonic and/or metamaterial cloaking for dielectric or metallic objects relies on "scattering cancellation" techniques that exploit the negative local polarizability of plasmonic materials and metamaterials. This cloaking phenomenon is relatively robust to changes in the design parameters, geometry and shape of the object, material loss, and frequency of operation. It has been recently extended to collections of particles, which are effectively systems of relatively larger size, and to multi-frequency operation. We have also been exploring the possibility of exploiting a collection of "anti-phase" scatterers surrounding the obstacle. These "satellites" are designed in such a way that the collective superimposition of the scattered waves interferes destructively, reducing the total scattering. Furthermore, we have also been studying how a sub-wavelength resonant surface can effectively provide an equivalent cloaking effect ("cage" scenario). Various applications of this concept are being explored including non-invasive sensors and probes in nanooptics and metrology.

Sample Publications

A. Alu and N. Engheta, "Multi-Frequency Optical Invisibility Cloak with Layered Plasmonic Shells," under review (since May 2007).

A. Alu and N. Engheta, "Cloaking and Transparency for Collections of Particles with Metamaterial and Plasmonic Covers," Optics Express, Vol. 15, No. 12, pp. 7578-7590, June 5, 2007.

A. Alu and N. Engheta, "Plasmonic Materials in Transparency and Cloaking Problems: Mechanism, Robustness, and Physical Insights," Optics Express, Vol. 15, No. 6, pp. 3318-3332, March 19, 2007.

M. G. Silveirinha, A. Alu, and N. Engheta, "Parallel Plate Metamaterials for Cloaking Structures," Physical Review E, Vol. 75, 036603 (16 pages), March 7, 2007.

A. Alu and N. Engheta, "Achieving Transparency with Plasmonic and Metamaterial Coatings," Physical Review E, Vol. 72, 016623 (9 pages), July 26, 2005 (erratum in Physical Review E, Vol. 73, 019906, January 24, 2006).

J. Li and N. Engheta, "Transparency of a Spherical Object Using Patterned Metallic Surfaces", a talk presented by J. Li at URSI 2007 North American Radio Science Meeting, July 2007, Ottawa, ON, Canada.

For details regarding this image, please see, A. Alu and N. Engheta, "Plasmonic Materials in Transparency and Cloaking Problems: Mechanism, Robustness, and Physical Insights," Optics Express, Vol. 15, No. 6, pp. 3318-3332, March 19, 2007.



For details regarding this image, please see, M. G. Silveirinha, A. Alu, and N. Engheta, "Parallel Plate Metamaterials for Cloaking Structures," Physical Review E, Vol. 75, 036603 (16 pages), March 7, 2007.