Strong coupling in organic and hybrid-semiconductor microcavity structures

Abstract

In this chapter we aim to introduce the reader to the phenomenon of strong exciton—photon coupling in photonic structures with an emphasis on planar microcavities. We will consider both organic and hybrid organic—inorganic systems. A simple description of classical strong coupling will be introduced through the use of a coupled oscillator model. The popular experimental techniques used to characterize strongly coupled microcavities will be described and we explain how to interpret experimental data. We give a brief history of the field of organic polaritonics in microcavities beginning at the first reported observation and covering the early experimental studies involving commonly used materials including J-aggregates, porphyrins, small organic molecules and molecular crystals. We then discuss more recent investigations aimed at determining the dynamics of polariton populations. A combination of steady state and ultrafast pump-probe experiments have allowed us to resolve the processes that lead from excited molecular states to observable polariton populations. An account of hybrid organic—inorganic polariton states (exciton hybridization) in microcavities is given, followed by the recent observation of polariton-mediated energy transfer between hybridized organic excitons. Recent milestones in the field of organic polaritons are described, specifically room-temperature organic polariton lasing and polariton condensation. Finally, there is a short review of optical systems other than planar microcavities that have been shown to support strong coupling of organic and hybrid exciton states