Lasing at the K-points of a honeycomb plasmonic lattice

We study lasing at the high-symmetry points of the Brillouin zone in a honeycomb plasmonic lattice. We use symmetry arguments to define singlet and doublet modes at the $\Kp$-points of the reciprocal space. We experimentally demonstrate lasing at the $\Kp$-points \changed{that is based on plasmonic lattice modes and two-dimensional feedback}. By comparing polarization properties to \changed{$T$-matrix} simulations, we identify the lasing mode as one of the singlets with an energy minimum at the $\Kp$-point enabling feedback. Our results offer prospects for studies of topological lasing in radiatively coupled systems.