UNIFORM COUPLING OF MICROWAVES TO NONLINEAR RESONANT MODES IN JOSEPHSON-JUNCTIONS

Uniform coupling of ac fields to Fiske modes in sine-Gordon systems is considered. We demonstrate that a uniformly distributed ac force gives rise to linear and symmetric phase-locked regimes for the Fiske modes in the limit of small amplitude perturbations. In the general case of large amplitudes of the ac force we demonstrate that phase locking can be described much like the Shapiro step for a single pendulum. We give a comprehensive analytical treatment of the problem and compare the results to direct numerical simulations of the perturbed sine-Gordon equation. Excellent agreement is found. © 1995 The American Physical Society.