Establish Rabi-energy variation under selective free-electron excitation without polariton population

Establish whether and how the Rabi energy of exciton–photon coupling changes with the photonic environment in metal–organic optical microcavities when the free-electron gas in the metallic cladding is selectively excited by infrared photons and no pump-induced population of polaritonic states is generated, thereby clarifying the expected strong-coupling modification under these conditions.

Background

Prior studies reported that even when the free-electron gas in the metallic layers is selectively excited using infrared photons—so that polaritonic states are not directly populated—polaritonic signatures remain detectable near the main exciton resonance in the visible. In such experiments, the observed signals correspond to strong-coupling conditions rather than long-lived polaritons.

Under these conditions, it is anticipated that changes to the photonic environment would modify the exciton–photon Rabi energy. However, such a change was not observed, and the existence and nature of this modification remain to be established. Resolving this question would clarify how metal-induced photonic perturbations influence the strength of exciton–photon coupling when polariton populations are not directly created.