Observations of standing solitons in a parametrically driven pendulum lattice

Abstract

Using a simple string-and-mass design, an experimental one-dimensional lattice of coupled pendulums has been constructed. Steady-state motion is obtained with a global parametric drive. Standing solitons of both the breather and kink type have been observed in the lower and upper cutoff modes, respectively. As the drive parameters (frequency and amplitude) are slowly varied, there can occur instabilities in which the character of the breather dramatically changes. In one region of the drive plane, the breather undergoes quasiperiodic motion in which the amplitude and width oscillate. In another region, the quasiperiodicity is absent and the energy is confined to nearly a single lattice site. The kinks have the remarkable feature that they can exist in modes other than the upper cutoff mode, and even between domains of different modes. These kinks differ from the upper cutoff type in that their structure depends upon the nature of the mismatch of the two domains.