Controlling the strong light-matter coupling in metal-dielectric optical resonators using spin-crossover molecules

¹ Laboratoire de Chimie de Coordination, CNRS UPR 8241, Université de Toulouse, 205 route de Narbonne, F-31077 Toulouse, France
² Laboratoire d’Analyse et d’Architecture des Systèmes, CNRS UPR 8001, Université de Toulouse, 7 avenue du colonel Roche, F-31400 Toulouse, France

^* Corresponding author: karl.ridier@lcc-toulouse.fr; azzedine.bousseksou@lcc-toulouse.fr

Published online: 18 October 2023

Abstract

We report the observation of (ultra)strong light-matter coupling, in the UV spectral region, between optical modes of a metal/dielectric bilayer nanocavity and the electronic excitations of spin-crossover (SCO) molecules. By thermally switching the SCO molecules between their low-spin and high-spin states, we demonstrate the possibility of fine-tuning the light-molecule hybridization strength, allowing a reversible switching between strong- (with Rabi splitting values of up to 550 meV) and weak-coupling regimes within a single photonic resonator. As a result, we show that spin-crossover molecular compounds constitute a novel, promising class of active nanomaterials in the context of tuneable and reconfigurable polaritonic devices.