Lasing in nanoparticle arrays with complex unit cells

In this work, we study lasing in plasmonic nanoparticle arrays with complex structures. Complex structures can be formed by unit cells that contain more than one particle or by creating supercells i.e. giant unit cells, which contain tens of particles. Here, we study lasing in supercell arrays which are based on a square array geometry. The supercell is created by leaving certain lattice sites empty, creating an aperiodic pattern. This supercell is repeated to form an array. We calculate the band structures of the arrays by combining the structure factors of the lattice geometries with an empty lattice approximation. We show that by leaving certain lattice sites empty, some of the destructive interference is removed, leading to additional dispersive branches. This provides new band edges that support lasing. We experimentally demonstrate lasing in such supercell arrays which show interesting lasing emission patterns and multimode lasing.