We report on systematic measurements of localized rotational modes in Josephson junction arrays. These modes, also known as rotobreathers, persist under the action of uniform bias force. In contrast to previous experiments, here we focus on systems with strong coupling between rotators. In ladders with either open or periodic boundary conditions, we observe a very rich variety of stable dynamic states including symmetric, asymmetric, combined, hybrid, coupled, and truncated modes. The switching scenarios between different states are discussed in detail.

• Received 22 March 2002

DOI:https://doi.org/10.1103/PhysRevE.66.016603