Plasmon Nanocavity Array Lasers: Cooperating over Losses and Competing for Gain.

Plasmon nanocavity array lasers leverage the combination of locally enhanced electromagnetic fields at localized particle plasmons with collective diffractive effects in periodic lattice geometries for low-threshold lasing with excellent coherence, line width, and directivity. This combination is enabled by the collective reduction of ohmic and radiative loss of plasmon antennas that hybridize to form surface lattice resonances. At the same time, candidate lasing modes compete for gain in the tight confines of the unit cell, where electromagnetic fields and population inversion are strongly structured in space, time, and polarization. This Perspective reviews the state of the art in understanding and manipulating this balance to combat losses and to optimize gain.