Superradiance of a 2D-spaser array
  We demonstrate that interacting spasers arranged in a 2D array of arbitrary size can be mutually synchronized allowing them to supperradiate. For arrays smaller than the free space wavelength, the total radiated power is proportional to the square of the number N of spasers. For larger arrays, the radiation power is linear in N. However, the emitted beam becomes highly directional with intensity of radiation proportional to N^2 in the direction perpendicular to the plane of the array. Thus, spasers, which mainly amplify near fields, become an efficient source of far field radiation when they are arranged into an array. 
A. V. Dorofeenko, A. A. Zyablovsky, A. P. Vinogradov, E. A. Andrianov,   A. A. Pukhov, and A. A. Lisyansky
cond-mat.mes-hall