Backward waves in carbon nanotubes structures with analogies to mushroom layers

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• Professor Sergei Tretyakov, Aalto University, School of Science and Technology
• Wednesday 04 May 2011, 15:00-16:00
• Blackett 630, Condensed Matter Physics Seminar.

If you have a question about this talk, please contact Ekaterina Shamonina.

Anisotropic materials with different signs of different components of the permittivity and, possibly, permeability tensors are called indefinite materials. Electromagnetic properties of these media are exhibited via unusual and practically useful phenomena, such as transformation of evanescent fields to propagating modes. Materials with negative permittivity in the visible part of the spectrum exist (noble metals), and indefinite media can be engineered using aligned nanowires. In the microwave part of the spectrum, indefinite media can be realized as artificial materials (metamaterials, in particular, loaded wire media). In both frequency regimes the main problem hindering prospective applications, is the high level of absorption losses. As to the wide terahertz (THz) frequency range, there are no known structures which would behave as electromagnetically indefinite materials. In this talk we will discuss the properties of periodic arrays of parallel single-wall carbon nanotubes (CNTs) and show that they behave as a low-loss indefinite media in the whole THz and mid-infrared frequency ranges. In particular, we show that a finite-thickness slab of CNTs supports the propagation of backward waves with very small attenuation in an ultra-broad frequency band. This property makes such a slab an almost perfect planar metamaterial. Interesting analogies with microwave “mushroom” high impedance surfaces will be drawn. We anticipate that CNT arrays can be used in future THz super-resolution focusing and detection devices, enhancing the radiation efficiency of small sources, and for novel THz and infrared devices based on the use of backward wave propagation properties of CNT array layers.

This talk is part of the Metamaterials series.

This talk is included in these lists:

• Blackett 630, Condensed Matter Physics Seminar
• Metamaterials

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