Soiree

Light-matter interactions at the nanoscale

Vincenzo Giannini

Lecturer in Theory of Metamaterials/Plasmonics, Imperial College London

Pablo Albella

Researcher in theory of nanophotonics and material science at Universidad de las Palmas de Gran Canaria, Visiting researcher at Imperial College London

Thursday 22nd February 2018
Time: 4pm
Venue: G.47B, Flowers Building, South Kensington Campus , ICL
Contact: Fernando Bresme
Tel: +44 (0)207 594 5886
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    Vincenzo Giannini
    Transparent metals

    We study light interaction with metal nanoparticles in extreme situation as compact and dense packeted metallic crystals (metamaterials).

    In this talk, I will show that a metamaterial made principally with metal nanoparticles can present an ultra-broadband region of high transparency (from near IR up to radio-waves). More importantly, such material does not have dispersion and present a refractive index that can easily be tuned. This finding allows to build lenses that work in an ultra-broadband region or realize transparent metals.

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    Pablo Albella
    Enhancing, controlling and guiding light with novel low-loss nanoantennas

    Optical antennas can transform light from freely propagating waves into highly localized excitations that interact strongly with matter. These nanoantennas are usually made of metallic (plasmonic) nanostructures and employed to obtain strong light-matter interactions at deep subwavelength size scales. However, its ohmic losses lead to temperature increase in the metal and surroundings. Another limitation of metals is the difficulty to generate optical magnetic response.

    In this talk I will first describe how the use of low-loss resonators made of high-permittivity dielectric materials (non-plasmonic) can also be very efficient in enhancing light, producing both, large near field enhancement and good scattering efficiencies while generating small heat radiation; showing them very interesting for surface enhance spectroscopy applications. Second, I will discuss another key aspect of these nanoantennas, which is the possibility of exciting nanoscale displacement currents that can lead to magnetic response, allowing the tuning of the amplitude and phase difference of electric and magnetic resonances independently, something that opens new paths to control the way light propagates at the nanoscale. I will conclude discussing how these novel type of nanoantennas when combined with plasmonic ones can offer interesting effects in non-linear optics.

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