PHASE-LOCKING BETWEEN FISKE AND FLUX-FLOW MODES IN COUPLED SINE-GORDON SYSTEMS

We investigate nonlinear resonant modes in coupled sine-Gordon systems with open boundary conditions. The system models coupled Josephson ju nctions with boundary conditions representing the situation where an e xternal magnetic field is applied. The so-called Fiske modes are found to exist in phase-locked states where the equivalent voltages across the individual coupled Josephson junctions are either identical or ide ntical with opposite signs. The analysis covers all Fiske modes includ ing the flux-flow region. We present a comprehensive comparison betwee n results on analytical treatment and direct numerical simulations of the coupled field equations.