I review our recent findings on lasing / condensation in plasmonic nanoparticle lattices<sup>1-5</sup>. The system properties can be tailored with high precision, including the lasing / condensation energies, linewidths, as well as the dimensionality of the feedback. For a 2-dimensional (2-D) square lattice, we identify lasing in the bright and the dark mode of the system<sup>1</sup>. By reducing the dimensionality to 1-D we observe the dark mode lasing2. In broken symmetry 2-dimensional rectangular lattices, we observe multimode lasing<sup>3</sup>. In honeycomb lattices with hexagonal symmetry, we observe 6 beams with specific off-normal angles and polarization properties corresponding to six-fold symmetry of such a lattice<sup>4</sup>. Finally, I review our recent studies in plasmonic Bose-Einstein condensation in plasmonic lattices<sup>5</sup>.
We study lasing in regular arrays made from aluminum nanoparticles. We show that these structures function as laser sources at visible wavelengths, even when scaled to an order of magnitude smaller areas compared to existing literature. The aluminum nanoparticles provide a robust platform for studying lasing in plasmonic systems, even when the optical losses are higher compared to silver or gold.
We show strong coupling involving three different types of resonances in plasmonic nanoarrays: surface lattice resonances, localized surface plasmon resonances on single nanoparticles, and excitations of organic dye molecules. We study spatial coherence properties of a plasmonic nanoarray covered with a dye molecule film by a double slit experiment. A continuous evolution of coherence from the weak to the strong coupling regime is observed. Finally, we show with magnetic nanoparticles how the intrinsic spin-orbit coupling of the material interplays with the symmetries of the nanoparticle array, and mention our latest results on light-matter interactions in plasmonic lattices.
We report on strong coupling between surface-plasmon polaritons and Rhodamine 6G molecules at room temperature.
As a reference to compare with, we first determine the dispersion curve of (uncoupled) surface plasmon
polaritons on a 50 nm thick film of silver. Consequently, we determine the dispersion curve of surface plasmon
polaritons strongly coupled to Rhodamine 6G molecules, which exhibits vacuum Rabi splitting. Depending on
the Rhodamine 6G concentration, we find splitting energies between 0.05 eV and 0.13 eV.