We propose a mechanism of coherent emission from driven vortices in stacked
intrinsic Josephson junctions. In contrast to super-radiance, which occurs only
for highly ordered vortex lattices, we predict resonant radiation emission from
weakly correlated vortex arrays. Our analytical results for the THz wave
intensity, resonance frequencies, and the dependence of THz emission power on
dissipation are in good agreement with the ones obtained by recent simulations.Comment: 2 figure