Miniaturized lasers enable applications in on-chip optical communication, medical imaging, and nanoscale optical displays. Compared to traditional lasers, plasmonic nanolasers can break the diffraction limit and support ultrasmall mode volumes, but unwanted multi-modal nanolasing exhibits both uncontrolled mode spacing and output behavior. Single band-edge states can trap slow light and function as high-quality optical feedback for microscale lasers to nanolasers. However, access to more than a single band-edge mode for nanolasing has not been possible because of limited cavity designs. We have developed plasmonic superlattices—finite-arrays of nanoparticles grouped into microscale arrays—to support multiple band-edge modes capable of multi-modal nanolasing at programmed emission wavelengths and with large mode spacings. Moreover, tuning NP size can provide an additional degree of freedom for manipulating the output behavior of different lasing modes. Modeling the superlattice nanolasers with a four-level gain system and a time-domain approach revealed that the accumulation of population inversion at plasmonic hot spots can be spatially modulated by the diffractive coupling order of the patches. Also, symmetry-broken superlattices exhibited switchable nanolasing between a single mode and multiple modes. Coherent nanoscale light sources with multiple tunable, on-demand optical modes can enable multiplexing for on-chip photonic devices and offer prospects for multi-modal laser designs.
