Multisoliton excitations in long Josephson junctions

The microwave emission from long Josephson tunnel junctions dc-current biased on zero-field and Fiske steps has been measured. The frequency and power variation on all steps of the narrow-linewidth radiation near the fundamental cavity-mode frequency and the observed transitions between different modes on a given step may be understood in a picture of multifluxon excitations with propagation of different bunched fluxon configurations depending on the current and magnetic field bias