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Center for Nonlinear Studies |
Optical properties of nanostructures comprised of noble metals have been a subject of intense research for many years due to various fascinating applications. Although linear optics of plasmonic materials is still of great interest, the nonlinear optical phenomena greatly enhanced by surface plasmon resonances are fast emerging. Beyond metallo-dielectric nanoconstructs and their properties are exciton-plasmon materials involving molecular assemblies and plasmonic systems. Under certain conditions when the coupling strength between molecules and local electromagnetic field associated with the plasmon resonance exceeds all dissipation rates, such a system enters the strong coupling regime. It is under these conditions one cannot really distinguish between molecular emitters and the electromagnetic radiation crafted by metal, i.e. they become hybridized exhibiting properties of both matter and light. One may note that combining the nonlinear response of metal with that of molecules in the strong coupling regime obviously requires treating both subsystems on equal footing. We combine computational electrodynamics for plasmons with quantum approach for quantum emitters in order to develop microscopic physical model of exciton-plasmon nanomaterials. We scrutinize optical properties of exciton-plasmon systems under strong coupling conditions by coupling Maxwell’s equations to nonlinear hydrodynamic model for metal and Liouville-von Neumann equations describing quantum emitters. The model is used to describe second harmonic generation in periodic arrays of nanoholes coupled to quantum emitters. Our model is also applied to analyze recent experiments investigating angular properties of the second harmonic generated by nanocrescents.
Host: Andrei Piryatinski