Plasmonically activated porous semiconductor microspheres for demonstration of random lasing with statistical interpretations

Aggregation-induced emission quenching in the solid state and photobleaching in liquid severely limit the use of organic dyes in lasing and other light emitting applications. Here, we address these limitations by coupling Rhodamine B (RhB) to porous ZnS microspheres and plasmonically active ZnS-Ag heterostructures. Porous ZnS microspheres enhance RhB fluorescence in both solid and dispersed states by suppressing aggregation-induced quenching and increasing light scattering, enabling solid-state emission and latent fingerprint restoration. As studied experimentally, light scattering role of ZnS becomes dominating at a concentration ∼ 0.12 g/L for enabling random lasing (RL) action in liquid phase. However, high ZnS concentrations lead to fluorescence quenching, limiting their capability for generating high quality RL emission. This limitation is overcome by ZnS-Ag microspheres, whose multiple metal-dielectric interfaces provide near-field plasmonic enhancement of RhB fluorescence. Using ZnS-Ag microspheres, we achieve stable coherent and incoherent RL emission from RhB in different geometries. Statistical properties of RL light reveal a Gaussian-to-Lévy transition of the coherent RL intensity fluctuations above a threshold excitation energy of ∼ 0.27mJ/pulse, which is further supported by photonic paramagnetic-to-glassy phase transition as confirmed through replica symmetry breaking analysis. These results establish a framework for controlling light-matter interactions between dye molecules and semiconductor scatterers, facilitating the use of these composites in prospective photonic applications.