Noise-induced Bessel-like oscillations of Shapiro steps with the period of the ac force

The frequency dependence of the dynamical-mode-locking phenomena in the presence of noise is studied in the one-dimensional ac driven dissipative Frenkel-Kontorova model. It was found that, besides producing the melting of Shapiro steps and decrease in the critical depinning force, noise may transfer a system by decreasing the dc threshold value into the high amplitude regime where the oscillations of the step width with the frequency of ac force will appear. Expressed as a function of the ac period, these oscillations have the Bessel-like form, the same as the well-known Bessel-like oscillations with amplitude. They may appear in any real system, irrespectively of the numbers of degrees of freedom, and strongly affect the stability of Shapiro steps, which is of great importance in the technical applications of interference effects.