Ideas from the Metamaterials Community

What we're reading... Why we like it...
The third-order nonlinear optical susceptibility of gold by R.W. Boyd, Z. Shi, and I. De Leon in Optics Communications, 2014
Posted: Jun 13, 2014
Boyd et al. conduct a review on reported values of the third-order nonlinear susceptibility of gold. They observe a span of over three orders of magnitude and notice that this span is closely related to experimental parameters such as pulse durations. This may very well have serious implications on the nonlinear optical properties of gold.
Characterizing metasurfaces/metafilms: the connection between surface susceptibilities and effective material properties by C. Holloway, E. Kuester, and A. Dienstfrey in IEEE Antennas and Wireless Propagation Letters, 2011
Posted: Jun 1, 2014
Holloway et al. develop a retrieval method that assigns metasurfaces/metafilms with effective surface susceptibilities. The method is based on the generalized sheet transition conditions (GSTCs), which allows the metasurface/metafilms to be replaced by an infinitely thin equivalent surface. The effective surfaces susceptibilities can be drawn from the GSTCs by calculating averaged fields across the surface, and connected to bulk effective material properties by identifying effective thickness. This method provides unique characterization of metasurfaces/metafilms, and can be useful in studying anisotropic thin films.
Broadening the cloaking bandwidth with non-Foster metasurfaces by P-Y. Chen, C. Argyropoulos, A. Alu in Physical Review Letters, 2013
Posted: Feb 13, 2014
Adding energy to a passive material can increase the bandwidth of invisibility cloaks. Chen and colleagues propose a thin metasurface that can reduce the scattering from a cylindrical object over a fairly large band of frequencies. Unlike most cloaks demonstrated to date, which are made using only passive metamaterials, the “non-Foster” cloak would be wired up with tiny electronic circuits that actively cancel the scattering that would otherwise be present from the cylinder.
Experimental demonstration of active electromagnetic cloaking by M. Selvanayagam, G. Eleftheriades in Physical Review X, 2013
Posted: Feb 13, 2014
Published nearly the same time as the Chen paper, a second paper by Selvanayagam and Eleftheriades actually provided an experimental demonstration of an active cloak. The Selvanayagam cloak involved a 12-element, active magnetic-dipole array encircling an aluminum cylinder. Sensing the incoming wave, the active circuits then create counter-currents that cancel the scattering of the cylinder—in some sense, like noise cancellation headphones! These fascinating papers are hopefully just the beginning of the era of active cloaking.
Nanostructured Holograms for Broadband Manipulation of Vector Beams by Jiao Lin, Patrice Genevet, Mikhail A. Kats, Nicholas Antoniou, and Federico Capasso, in Nano Letters, 2013
Posted: Sep 19, 2013
Lin et al. provide a new approach for the fabrication of meta-surfaces. Building on the principles of detour phase holography, the manuscript presents a design that allows control of amplitude, phase, and polarization, allowing the fabrication of complex diffraction devices.
Transformation optics and metamaterials at infrared wavelength: engineering of permittivity and permeability by Rasta Ghasemi, Aloyse Degiron, Xavier Le Roux, Anatole Lupu, and André de Lustrac in Proc. SPIE 8771, Metamaterials VIII, May 6, 2013
Posted: Sep 19, 2013
Transformation optics allows one to design optical devices with unique properties, such as invisibility cloaks. However, the optical properties prescribed by transformation optics are usually difficult to fabricate, particularly at optical wavelengths. In this work, Ghasemi et al. demonstrate the control of both the permittivity and the permeability in the near infrared.
Analogue Transformations in Physics and Their Applications to Acoustics by C. Garcia-Meca, S. Carloni, C. Barcelo, G. Jannes, J. Sanchez-Dehesa & A. Martinez in Nature Scientific Reports, 2013
Posted: Jun 20, 2013
This Nature Scientific Report from a European collaboration expands the concept of space-time cloaking, introduced recently for electromagnetic waves, and applies it to acoustics. Through numerical simulations, the group demonstrates the use of relativistic form-invariance for enabling acoustic cloaking in a moving medium. They believe this mathematical apparatus will lead to broad applications in other areas of physics.
Quantum Plasmonics: Nonlocal effects in coupled nanowire dimer by T.V. Teperik, P. Nordlander, J. Aizpurua, A. G. Borisov in physics.optics
Posted: Jun 18, 2013
The nonlocal quantum response of metal has attracted a great deal of interest in the last year. In this letter Teperik et al. were able to carry out fully quantum calculations for plasmonic dimers with relatively large size. A interesting comparison with results from classical electromagnetic calculations based on local and nonlocal hydrodynamic response reveals the shortcomings of classical treatments.
Liquid crystal based nonlinear fishnet metamaterials by Alexander Minovich, James Farnell, Dragomir N. Neshev, Ian McKerracher, Fouad Karouta, Jie Tian, David A. Powell, Ilya V. Shadrivov, Hark Hoe Tan, Chennupati Jagadish, and Yuri S. Kivshar in Applied Physics Letters, 2012
Posted: May 1, 2013
In broad strokes, the initial surge of research in metamaterials focused on achieving exotic and extreme optical properties, while more recent studies pursue functionality and tunability. In this context, Minovich et. al. take a canonical optical metamaterial, the metal 'fishnet,' and achieve both optically and electrically induced tunability by infiltrating the fishnet with liquid crystals, demonstrating an intriguing path towards compact and dynamic optical components.
Optical modulation of millimeter-wave beams using a semiconductor substrate by Gallacher, Tom F., et al. in Microwave Theory and Techniques, IEEE Transactions
Posted: Apr 29, 2013
This paper uses an optically excited semiconductor slab to make a reconfigurable beam forming mask for millimeter-waves. Such optically excited semiconductors may be an interesting way to produce tunable metamaterials.