Electromagnetic waves with a negative group velocity in a randomly inhomogeneous Josephson junction

Electromagnetic waves in a randomly inhomogeneous Josephson junction have been investigated by the averaged Green’s function method for a nonmonotonic decay of the correlations of inhomogeneities. Modifications of the spectrum and the decay of these excitations caused by spatial fluctuations of the critical current of the Josephson junction have been studied. The regions of the values of the frequency, the wave number, and the stochastic parameters of the medium, at which the waves have a negative group velocity, have been determined.