Optical Characterization of Size- and Substrate-Dependent Performance of Ultraviolet Hybrid Plasmonic Nanowire Lasers

Nanowire-based plasmonic lasers are now established as nano-sources of coherent radiation, appearing as suitable candidates for integration into next-generation nanophotonic circuitry. However, compared to their photonic counterparts, their relatively high losses and large lasing thresholds still pose a burdening constraint on their scalability. In this study, the lasing characteristics of zinc oxide (ZnO) nanowires on silver (Ag) and aluminum (Al) substrates, operating as optically-pumped short-wavelength plasmonic nanolasers, are systematically investigated in combination with the size-dependent performance of the hybrid cavity. A nanomanipulation-assisted single nanowire optical characterization combined with high-throughput photoluminescence spectroscopy enabled the correlation of the lasing characteristics to the metal substrate and the nanowire diameter. The results evidence that the coupling between excitons and surface plasmons is closely tied to the relationship between substrate dispersive behavior and cavity diameter. Such coupling dictates the degree to which the lasing character, be it more plasmonic- or photonic-like, can define the stimulated emission features and, as a result, the device performance.