# News

## Analytical theory of nonlinear metamaterials: design on demand

Monday, 11 October 2010
Poutrina et al. developed an analytical approach allowing to relate a particular geometry of a metamaterial unit cell incorporating nonlinear elements to the effective nonlinear susceptibilities characterizing the resulting effective medium. The approach allows the prediction, analysis, and possible enhancement of the nonlinear response of a metacrystal, exploiting and proving a long-predicted concept of the increased nonlinear response in metamaterial structures. The theory shows an excellent...

## Quantitative characterization of nonlinear metamaterials

Wednesday, 6 October 2010
In a paper published in Applied Physics Letters, Larouche et al. present the first quantitative characterization of nonlinear metamaterials. Using an approach based on transfer matrices previously developed in the CMIP, they determine the quadratic nonlinear magnetic susceptibility of a slab of varactor-loaded split ring resonators to be 3.5 m/V. This gigantic value confirms qualitative predictions found in the literature and supports the validity of an analytical model developed by Poutrina et...

## Acoustic cloaking transformations from attainable material properties

Tuesday, 5 October 2010
The acoustic "sisters" of electromagnetic invisibility cloaks are long-sought devices that could defeat sonars. The existence of two types of acoustic waves in elastic media, however, makes acoustic cloaking very hard to achieve. The paper by Yaroslav Urzhumov and co-workers, published recently in the New Journal of Physics (July 12, 2010), is the first report on the feasibility of building an acoustically undetectable elastic cloak. Acoustic cloaking transformations from attainable material...

## Plasmonic Multi-Mode Interference Couplers

Wednesday, 21 October 2009
The MMI coupler is a key component in optical integrated circuits. Its main function is to combine or split optical signals, enabling the development of powerful multiplexing devices and integrated sensors. In a paper published in Optics Express (September 28, 2009 issue), Yu-Ju Tsai and co-workers investigate metallic MMI couplers that support long-range surface plasmons instead of conventional electromagnetic waves. Although the use of metals introduces material losses in the system, the...

## Electromagnetic source transformations using superellipse equations

Tuesday, 12 May 2009
Transformation optics can be used to design media with unique properties for the manipulation of electromagnetic waves. The transformation optical approach can be used not only to control the path of light, but also to change the way that currents and charges (or sources) behave when they interact with light. The interaction of electromagnetic waves is fundamental in the design of antennas.  In the latest issue of Applied Physics Letters, Jeffery Allen and colleagues demonstrate several...

## Duke to lead program on Transformation Optics sponsored by the Army Research Office

Tuesday, 12 May 2009

## Broadband non-resonant metamaterial used for ground plane cloaking

Friday, 16 January 2009
There has been a large amount of interest generated by recent work on invisibility cloaking. While the concept of invisibility has many corollaries in popular fiction which inspire the imagination, from the Harry Potter stories to Predator, researchers are taking only the first steps- both theoretical and experimental- towards these sci-fi goals. The general approach being used, which combines transformation optics with metamaterials operating in the microwave region of the electromagnetic...

## The transformation optical approach to antenna design

Monday, 23 June 2008
Transformation optics is a new tool for the design of electromagnetic media. Using transformation optics, researchers can visualize the interaction of certain complex materials with light as a warping of space. The physical basis underlying this connection, however, extends also to sources of light—electric currents, for example. In a recent paper published in Optics Express, Nathan Kundtz and colleagues illustrate the application of transformation optics to electric currents. In one example,...