Microcavity-enhanced rare-earth ion emission

Unique to rare-earth ions, their partially filled 4f shells are shielded from the surrounding environment, thus rendering extraordinary optical and spin coherence properties of the rare-earth ions. Despite their remarkable optical properties including sharp optical transitions and weak dependence on the external environment, the application of the rare-earth ions in lighting and quantum technologies has often been hindered by their weak oscillator strength and faint emission. Rare-earth ion molecular complexes offer the opportunity to overcome this limitation by sensitizing the rare-earth ions with antenna ligands. In this work, we modify the photoluminescence (PL) properties of rare-earth ion molecular complexes by coupling them to an open Fabry-Pérot cavity. The precisely adjustable cavity length of the open cavity allows in situ tuning of its resonance wavelength. By scanning the cavity mode through the rare-earth ion emission and in situ monitoring the corresponding PL emission in the momentum space, a significant PL enhancement and lifetime shortening can be achieved when in the resonance configuration. This work indicates the natural compatibility of the rare-earth ion molecules with microcavity structures and paves the way towards their integration with photonic devices.