Devil's Staircase in an Optomechanical Cavity

TL;DR

This paper investigates how periodic laser power modulation can induce phase locking in self-excited oscillations within an optomechanical cavity, revealing a complex structure of locking regions related to Farey sequences.

Contribution

It introduces a theoretical one-dimensional map to describe phase dynamics and links phase locking regions to Farey hierarchy, advancing understanding of optomechanical oscillation control.

Findings

Phase locking occurs at specific ratios of modulation and SEO frequencies.

Low amplitude modulation can induce phase locking near rational frequency ratios.

The theoretical model partially agrees with experimental observations.

Abstract

We study self-excited oscillation (SEO) in an on-fiber optomechanical cavity. While the phase of SEO randomly diffuses in time when the laser power that is injected into the cavity is kept constant, phase locking may occur when the laser power is periodically modulated in time. We investigate the dependence of phase locking on the amplitude and frequency of the laser power modulation. We find that phase locking can be induced with a relatively low modulation amplitude provided that the ratio between the modulation frequency and the frequency of SEO is tuned close to a rational number of relatively low hierarchy in the Farey tree. To account for the experimental results a one dimensional map, which allows evaluating the time evolution of the phase of SEO, is theoretically derived. By calculating the winding number of the one dimensional map the regions of phase locking can be mapped in the plane of modulation amplitude and modulation frequency. Comparison between the theoretical predictions and the experimental findings yields a partial agreement.