Dynamics of impurity attraction and repulsion of an intrinsic localized mode in a driven 1-D cantilever array

TL;DR

This study investigates how laser-induced impurities in a micromechanical cantilever array influence the attraction or repulsion of intrinsic localized modes, revealing the role of linear local modes and nonlinear effects in their interaction.

Contribution

It demonstrates the mechanisms of impurity-ILM interactions in a driven 1-D cantilever array, highlighting the significance of linear local modes and nonlinear effects, supported by experiments and simulations.

Findings

Impurities can attract or repel ILMs depending on their position.

Vibrational hopping occurs when ILM and linear local modes are symmetrically placed.

Nonlinear effects amplify the impurity-ILM interaction.

Abstract

Both low frequency and high frequency impurity modes have been produced in a SiN micromechanical cantilever array by illumination with either an infrared or visible laser. When such laser-induced impurities are placed near a driven intrinsic localized mode (ILM) it is either repelled or attracted. By measuring the linear response spectrum for these two cases it was found that vibrational hopping of the ILM takes place when the natural frequency of the ILM and an even symmetry linear local mode are symmetrically located about the driven ILM frequency so that parametric excitation of these two linear modes is enhanced, amplifying the lateral motion of the ILM. Numerical simulations are consistent with these signature findings. It is also demonstrated that the correct sign of the observed interaction can be found with a harmonic lattice-impurity model but the magnitude of the effect is enhanced in a nonlinear lattice.