Plasmonics: enhancing and guiding fields at nanoscale – Niels Bohr Institute - University of Copenhagen

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Plasmonics: enhancing and guiding fields at nanoscale

Prof. Sergey I. Bozhevolnyi

Institute of Sensors, Signals and Electrotechnics (SENSE), University of Southern Denmark, Odense

Abstract

The explosive progress in nanoscience has led to uncovering and exploring numerous physical phenomena occurring at nanoscale. One of the main research directions in nano-optics is the search for configurations that efficiently interconvert propagating (µm-sized) and strongly localized (nm-sized) optical fields resulting thereby in strongly enhanced local fields, which are indispensable for optical characterization, sensing and manipulation at nanoscale. After briefly reviewing various configurations used for creating enhanced optical fields, a novel route exploiting retardation-based resonances involving (slow) surface plasmons (SPs) supported by metal nanostructures is considered in detail [1-3]. It is argued that the suggested configuration can be advantageously used in order to realize strong and robust field enhancement effects.

Photonic components are superior to electronic ones in terms of operational bandwidth but suffer from the diffraction limit that constitutes a major problem on the way towards miniaturization and high density integration of optical circuits. The degree of light confinement in dielectric structures, including those based on the photonic band-gap effect, is fundamentally limited by the light wavelength in the dielectric used. The main approach to circumvent this problem is to take advantage of hybrid nature of SPs whose subwavelength confinement is achieved due to very short (nm-long) penetration of light in metals. After briefly reviewing various SP guiding configuration the results of our investigations of subwavelength photonic components utilizing SP modes propagating along channels cut into gold films are overviewed [4-6], demonstrating first examples of ultracompact plasmonic components that pave the way for a new class of integrated optical circuits [7].

 

1. T. Søndergaard and S. I. Bozhevolnyi, Slow-plasmon resonant nanostructures: Scattering and field enhancements, Phys. Rev. B 75, 073402 (2007).

2. S. I. Bozhevolnyi and T. Søndergaard, General properties of slow-plasmon resonant nanostructures: nano-antennas and resonators, Opt. Express 15, 10869 (2007).

3. G. D. Valle, T. Søndergaard, and S. I. Bozhevolnyi, Plasmon-polariton nano-strip resonators: from visible to infra-red, Opt. Express, 2008, vol.16, No.10, pp.6867-6876.

4. S. I. Bozhevolnyi, V. S. Volkov, E. Devaux, and T. W. Ebbesen, Channel plasmon-polariton guiding by subwavelength metal grooves, Phys. Rev. Lett. 95, 046802 (2005).

5. S. I. Bozhevolnyi, V. S. Volkov, E. Devaux, J.-Y. Laluet, and T. W. Ebbesen, Channel plasmon subwavelength waveguide components including interferometers and ring resonators, Nature 440, 508 (2006).

6. V. S. Volkov, S. I. Bozhevolnyi, E. Devaux, J.-Y. Laluet, and T. W. Ebbesen, Wavelength selective nanophotonic components utilizing channel plasmon polaritons, Nano Lett. 7, 880 (2007).

7. T. Ebbesen, C. Genet, and S. I. Bozhevolnyi, Surface-plasmon circuitry, Physics Today, May 2008, pp.44-50.