Unveiling spontaneous emission enhancement mechanisms in metal–insulator–metal nanocavities

Recent advances in the development of a nanocavity based on a metal–insulator–metal(MIM) structure have provided a great opportunity to enhance the performance of photonic devices. However, the underlying physics behind the emission enhancement obtained from such cavities is under debate. Here, in this work, we designed and investigated MIM nanocavities to reveal the mechanisms for the observed 260-fold photoluminescence enhancement from LDS 798 fluorescent dye. This study provides a pathway to engineer the emission properties of an emitter not only through the enhancement of the Purcell factor but mainly through enhancement of the excitation rate. Our numerical simulations support the experimentally acquired results. We believe an MIM cavity and dye-based hybrid system design based on the revealed enhancement process and structural simplicity, will provide more efficient, lithography free, and low-cost advanced nanoscale devices.