Multiple Interacting Photonic Modes in Strongly Coupled Organic Microcavities

TL;DR

This paper investigates how multiple photonic modes interact with molecular ensembles in strongly coupled microcavities, revealing that off-resonant modes induce dissipation that limits coherence, challenging traditional strong coupling models.

Contribution

It provides a microscopic quantum analysis of multimode organic microcavities, highlighting the impact of off-resonant modes on light-matter coherence and the limitations of vacuum Rabi splitting as a coherence indicator.

Findings

Vacuum Rabi splitting is necessary but not sufficient for strong coupling.

Off-resonant cavity modes cause molecular dipole hybridization with dissipation channels.

Dissipative processes from multimode interactions limit coherence in organic microcavities.

Abstract

Room temperature cavity quantum electrodynamics with molecular materials in optical cavities offers exciting prospects for controlling electronic, nuclear and photonic degrees of freedom for applications in physics, chemistry and materials science. However, achieving strong coupling with molecular ensembles typically requires high molecular densities and substantial electromagnetic field confinement. These conditions usually involve a significant degree of molecular disorder and a highly structured photonic density of states. It remains unclear to what extent these additional complexities modify the usual physical picture of strong coupling developed for atoms and inorganic semiconductors. Using a microscopic quantum description of molecular ensembles in realistic multimode optical resonators, we show that the emergence of a vacuum Rabi splitting in linear spectroscopy is a necessary but not sufficient metric of coherent admixing between light and matter. In low finesse multi-mode situations we find that molecular dipoles can be partially hybridised with photonic dissipation channels associated with off-resonant cavity modes. These vacuum-induced dissipative processes ultimately limit the extent of light-matter coherence that the system can sustain.