Dipolar and quadrupolar excitons coupled to a nanoparticle-on-mirror cavity
Álvaro Cuartero-González, Antonio I. Fernández‐Domínguez
Abstract
We investigate plasmon-emitter interactions in a nanoparticle-on-mirror cavity. We consider two different sorts of emitters: Those that sustain dipolar transitions and those hosting only quadrupolar, dipole-inactive excitons. By means of a fully analytical two-dimensional transformation optics approach, we calculate the light-matter coupling strengths for the full plasmonic spectrum supported by the nanocavity. We reveal the impact of finite-size effects in the exciton charge distribution and describe the population dynamics in a spontaneous emission configuration. Pushing our model beyond the quasistatic approximation, we extract the plasmonic dipole moments, which enables us to calculate the far-field scattering spectrum of the hybrid plasmon-emitter system. Our findings, tested against fully numerical simulations, reveal the similarities and differences between the light-matter coupling phenomenology for bright and dark excitons in nanocavities.