ABSTRACT

Over the past decade, intense research into the properties of engineered, artificial materials has shown that remarkable effective material properties can be realized by controlling the geometry of sub-wavelength, metallic circuits. Metamaterials have been demonstrated that support material properties that do not appear in naturally occurring materials. The negative index medium that precipitated the field a decade ago provided an early and compelling example. Leveraging the control over material parameters now available, we can design new devices based on precisely patterned spatial gradients in the anisotropic tensor components of an effective medium. The “invisibility cloak,” demonstrated by our group at Duke in 2006, is just such a possibility, though there are many others. By applying the emerging design technique of Transformation Optics to conventional refractive or gradient optical elements, unusual and potentially advantageous optical devices can be rapidly and simply designed, leaving the complication to the material properties.

As remarkable as their passive material properties are, metallic metamaterials also have the capability to provide new classes of active, tunable and nonlinear media. Because the electromagnetic fields are strongly enhanced within the capacitive regions of metallic, resonant metamaterials, it is possible to hybridize the response of conventional materials introduced into the high field regions of metamaterial composites with the engineered, passive properties of the host metamaterial. Because metallic metamaterials are generally more absorptive than are conventional materials, it becomes important for devices that any useful function require as short a propagation path as possible. Hybrid metamaterials are thus good candidates for applications at infrared and visible wavelengths, since they can perform a useful operation on incoming light—such as wave mixing, modulation, tuning or harmonic generation—within a minimal propagation length.

Progress over the past decade in metamaterials has been rapid and prodigious, with numerous exciting and compelling demonstrations of new wave propagation phenomena. Going forward, an emphasis will undoubtedly be on transitioning the emerging concepts and techniques to applications of practical interest. Still, there is much more to discover on the fundamental side, as we continue to realize greater and greater control over the electromagnetic and other physical properties of artificially structured media!

Short Biography, David R. Smith

Dr. David R. Smith is currently the William Bevan Professor of Electrical and Computer Engineering Department at Duke University and serves as Director for the Center for Metamaterial and Integrated Plasmonics. He holds a secondary faculty appointment in the Physics Department at Duke University and a Visiting Professor of Physics at Imperial College, London. Dr. Smith received his Ph.D. in 1994 in Physics from the University of California, San Diego (UCSD). Dr. Smith’s research interests include the theory, simulation and characterization of unique electromagnetic structures, including photonic crystals, metamaterials and plasmonic nanostructures. Smith and his colleagues demonstrated the first left-handed (or negative index) metamaterial at microwave frequencies in 2000, and also demonstrated a metamaterial “invisibility cloak” in 2006. In 2005, Dr. Smith was part of a five member team that received the Descartes Research Prize, awarded by the European Union, for their contributions to metamaterials and other novel electromagnetic materials. In 2006, Dr. Smith was selected as one of the “Scientific American 50.” In 2009, Dr. Smith was named a "Citation Laureate" by Thomson-Reuters ISI Web of Knowledge, for having among the most number of highly cited papers in the field of Physics over the past decade.

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