Speaker: Prof. Mikhail Vasilevskiy
Abstract Details:
Surface plasmon-polariton (SPP) is an evanescent electromagnetic wave induced by thecoupling of the electromagnetic field to conduction electrons near the surface of a metal or a semiconductor. Its amplitude decays exponentially at both sides of the interface. The SPP properties are determined by the dielectric function of the conductor (related to its frequencydependent conductivity) and the dielectric constants of the surrounding media.
Part I:
SPPs in two types of multilayer nanostructures will be considered: (i) monolayer grapheme sandwiched between two dielectrics, and (ii) metallic film combined with one or several layers of semiconductor nanocrystal (NC) quantum dots (QDs) produced by chemical synthesis and dispersed in a dielectric (PMMA) matrix. It will be shown that one can explore the high-frequency conductivity of graphene,together with the ability of controlling its electronic density by an applied gate voltage, in order to achieve resonant coupling between an external electromagnetic radiation and SPPs in the graphene layer. This opens the possibility of electrical control of the intensity of light reflected by the structure in so called attenuated total internal reflection (ATR) configuration by switching between the regimes of (nearly) total reflection and total absorption. The predicted effect can be used to build graphene-based optoelectronic switches operating in
the THz frequency range.
Part II:
Recent experiments demonstrated the possibility of strong coupling between excitons confined in NC quantum dots and SPPs propagating along the interface of a silver film and the QD layer deposited on top of it. It will be shown that the SPP coupling to the QD excitons can be rather strong unless the dispersion of the QD size is too large or the dots are too far from the metal/dielectric interface. This resonant coupling can be used for controllable pumping the dots in order to explore their unique luminescence properties. In particular, it opens the possibility to control the relative intensity of light of different color, emitted by the QDs of different size.
About the Speaker: Mikhail Vasilevskiy was graduated from N. I. Lobachevskii University in Gorkii, USSR, in 1981 and received his PhD in Physics and Mathematics from the same University in 1985. He worked as a professor of Physics in the same University and as a researcher at the Institute for Physics of Microstructures, Russian Academy of Sciences. He also was a post-doctorate researcher in Essex University, UK, and visiting professor in the Universidade Federal Fluminense, Brazil. Since 1999 Mikhail Vasilevskiy is a professor of Physics at the School of Science of Minho University (UM) and a researcher at the UM Centre of Physics where he currently serves as Director. His scientific interests are focused on the Physics of Semiconductor Nanostructures, in particular, on the theory and modelling of the electronic and optical properties of quantum dots. He authored and co-authored one book and more than 100 papers published in peer-review journals.
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