Light-matter interactions in plasmonic cavities

Trabajo presentado en SPICE Workshop on Molecular Electro-Opto-Spintronics, celebrado en Mainz (Alemania), del 15 al 18 de octubre de 2019A plasmonic nanogap is a superb configuration to explore the interplay between electron currents and light. Light scattered off, or emitted from a nanogap carries the information of the surrounding electromagnetic environment with it. In metallic cavities with ultrasmall gaps, electron currents across the gap at optical frequencies modify the properties of the cavity plasmons and efficiently produce a strong nonlinear optical response. All these effects can be further controlled when a bias is applied across the gap, enabling the possibility of active control of the light emitted from the cavity, as well as that of the corresponding nonlinearities. This situation becomes even more interesting when a molecule is located in the gap of the plasmonic cavity or in its proximity, with the molecule playing an active role either in the electromagnetic coupling with the plasmonic cavity, or even participating in processes of charge injection and transfer which are also revealed through molecular electroluminescence. We will address situations of light emission in electron tunneling configurations, with an emphasis on the interaction between a molecular emitter and a tunneling plasmonic cavity both in the weak and strong coupling regimes, as revealed both in light absorption and in emission. Strong coupling between a molecule and a plasmonic cavity shows great technological potential as it produces hybrid molecule-cavity polaritonic states which can be used for quantum information or in induced chemical reactivity. Last, but not least, the situation where a photocurrent can be induced by a single-cycle optical pulse will be presented, showing the possibility of generating a very rich ultrafast nonlinear between ultrafast optics and photoelectron dynamics within the nanogap