Grand Séminaire d'Institut

Vendredi 12 Avril 2024 à 11h00.

Plasmon-Polaritons in Nanoparticle Supercrystals: Experiments and Theory

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In this work we discuss the Light-Matter interaction in the context of supercrystals formed by metallic nanoparticles. The plasmonic excitations of the particles in the periodic structure interact forming collective excitations which couple to the electromagnetic field to create hybrid light-matter excitations known as plasmon-polaritons. The dispersion relations of the plasmon polaritons depend both on the sizes of the composing nanoparticles and on the specific crystalline structure of the supercrystals. For particles large in comparison to the lattice parameter the light-matter interaction can be amplified to enter the ultra-strong and the deep-strong light-matter coupling regimes. In the deep-strong coupling regime, the energy associated to the light-mattter interaction exceeds the energies of the bare plasmons and photons leading to interesting physical phenomena. We also present a theoretical framework which can be used to describe the light-matter interaction in these systems and help guide the development of new structures for possible plasmonic and photonic applications. Our model excellently reproduces results of finite difference time domain simulations. It also provides detailed insight into the emergence of the polariton states. Our results pave the way for a better understanding of the quantum properties of metallic nanoparticle supercrystals in the deep-strong coupling regime.

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