Ultralong Temporal Coherence in a Solid-State Plasmonic Nanolaser

Coherence is one of the most distinctive properties of lasers, which differentiates them from conventional light sources. Nowadays, there is a strong interest in the development of coherent sources at the nanoscale, namely nanolasers, for many advanced applications in nanophotonics and quantum optics. In the present work, we experimentally investigate the temporal coherence properties at room temperature of a fully solid-state plasmonic nanolaser consisting of an ordered hexagonal array of tapered aluminum nanocones coupled to a dye-doped polymeric thin film. An ultralong temporal coherence is measured, with a coherence time of about 30 ps and a corresponding coherence length of about 8.8 mm. This result is driven by the combination of the high quality of the plasmonic nanoarray and the small thickness of the gain medium, while the resonant pumping on one lattice mode of the nanoarray is expected to contribute to lowering the lasing threshold. Such a long coherence is more than 1 order of magnitude longer than the state-of-the-art coherence properties reported so far for plasmonic lattice nanolasers, making the investigated system highly promising for the realization of coherent nanosources operated at room temperature.