Lasing from Finite Plasmonic Nanoparticle Lattices

Small lasers can generate coherent light for integrated photonics, in vivo cellular imaging, and solid-state lighting. Unlike conventional lasers, plasmonic lasers can generate coherent light at subwavelength scales, although cavity architectures based on metal films and semiconducting gain exhibit large radiative losses and lack directional emission. In contrast, 2D metal nanoparticle arrays surrounded by organic dyes can support lasing with high directionality at room temperature. However, the relationship between the number of nanoparticles in a finite lattice and their lasing emission characteristics is unknown. Here we show that the number of units in 2D gold nanoparticle lattices is critical to generate robust cavity resonances and lasing emission. Narrower lattice plasmons associated with stronger electromagnetic near fields are observed as the nanoparticle number increases. Experimentally, we demonstrate lasing from a 30 x 30 nanoparticle lattice. Semiquantum modeling indicates lower lasing thresholds and faster population inversion dynamics with higher nanoparticle numbers. These results suggest that finite lattices of nanoparticles integrated with gain can function as independent, coherent light sources for optical multiplexing and lab-on-a-chip applications.