Superradiant Optical Emitters Coupled to an Array of Nanosize Metallic Antennas

We study the properties of an array of Au ring nanoantennas fed by an ensemble of coherent emitters. The luminescence of the emitters is strongly enhanced at certain wavelengths due to the excitation of two types of resonances-the diffractive Rayleigh anomalies associated with the opening of new diffraction orders and the localized surface plasmons of the nanoantennas. We show that the two families of resonances can spectrally overlap and lead to anticrossings or cumulative enhancements depending on the symmetries of the modes. This rich optical behavior induces marked changes in the linewidth, shape, and amplitude of the peaks and could be potentially used to tune the luminescence of superradiant sources with new flexibility.