Superconducting metamaterials

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• Dr. A. Roger Buckingham, University of Southampton
• Friday 27 May 2011, 14:00-15:00
• Physics East 217.

If you have a question about this talk, please contact Elizabeth Blackburn.

Superconductors may be considered as plasmonic media, exhibiting both a negative dielectric constant and a dominant kinetic resistance. Use of superconductors in metamaterials permits the control and reduction of the hereditary Joule losses and introduces nonlinearities in response to external stimuli, paving the way for low-loss, high Q-factor and tunable metamaterials. I will provide an overall summary of the University of Southampton’s EPSRC Centre for Photonic Metamaterials work on superconducting metamaterials and plasmonmics. I shall begin with a summary of metamaterials and the reasoning behind using superconductors. I will include details of sample fabrication and characterization before presenting some of our original work on the temperature control of Fano (asymmetric) resonances in split ring structures. Metamaterials supporting Fano-type resonances have attracted considerable attention for use in sensor, nonlinear and switching applications due to their sharp dispersion. In an asymmetric split ring the resonance lifetime and the Q-factor are controlled by the ring asymmetry, and in the absence of Joule losses may be made infinitely high. Thus control of the Joule losses through the use of superconducting materials is important in achieving a sharp resonant response. Furthermore, several groups have proposed using the quantum properties of the superconducting state to generate the nonlinear response of metamaterials on the quantum level. These suggestions revolve around a central concept of Josephson junctions and accordingly are associated with magnetic flux quantization. I shall then go on to demonstrate the first practical realization of such a quantum metamaterial. Finally, I will show that in superconductors, the formation of Cooper-pairs below a critical temperature leads to a dominant kinetic inductance permitting the existence of plasmonic excitations in the terahertz part of the spectrum. Superconducting waveguides supporting low-loss plasmon waves could be used for the transport of information in compact terahertz data processing circuits. Moreover, since the electromagnetic characteristics of superconductors may be readily altered by external stimuli such as magnetic field, electrical current, optical illumination or temperature, this plasmon signal may be efficiently controlled in data processing and interconnect applications. I will present some early results centred on the plasmonic properties of superconductors focussing on the temperature-dependent effects of extraordinary transmission.

This talk is part of the Condensed Matter Physics Seminars series.

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• Bham Talks
• Cond. Mat. seminar
• Condensed Matter Physics Seminars
• Physics East 217
• What's on in Physics?

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