Discrete intrinsic localized modes in a microelectromechanical resonator

TL;DR

This paper demonstrates the excitation and observation of intrinsic localized modes (ILMs) in a standalone microelectromechanical resonator, revealing their dynamic behaviors and underlying mechanisms in a mechanical system.

Contribution

It introduces a novel experimental realization of ILMs in a mechanical resonator using piezoelectric driving and optical visualization, expanding ILM studies beyond traditional physical systems.

Findings

ILMs observed as spectral bushes at frequencies below the drive frequency

ILMs excited via autoparametric instability of a sub-harmonic mode

ILMs exhibit dynamic behaviors like attraction-repulsion and hopping

Abstract

Intrinsic Localized Modes (ILMs) or Discrete Breathers (DBs) are produced through a non-linear vibration localization phenomenon. While Anderson localization is due to lattice defects, the nonlinearity of lattices provides the basis for ILM excitation. Over the past two decades, these ILMs have been realized in a wide range of physical systems including photonic crystals, nonlinear atomic lattices, anti-ferromagnets, coupled Josephson junction arrays and coupled cantilevers. This paper brings out the feasibility of exciting ILMs in a standalone mechanical resonator. Through piezoelectric driving and optical visualization, various intriguing features of ILMs have been recorded. The ILMs in our system are observed as spectral bushes and their frequencies are much lower than that of the drive frequency. The excitation of ILMs is mediated through large amplitude instability following autoparametric excitation of a sub-harmonic mode. The spatial prevalence of discrete ILM excitations is at antinodes of the sub-harmonic mode. Further, the ILMs have been observed to be time-variant and various events including attraction-repulsion (or splitting-merging) of ILMs and hopping occur during the time evolution of ILMs.