Observation of opto-mechanical multistability in a high Q torsion balance oscillator

TL;DR

This paper reports the experimental observation of multiple stable states in a macroscopic torsion oscillator caused by radiation pressure in an optical cavity, revealing potential for noise-enhanced gravity measurements.

Contribution

It demonstrates the first observation of opto-mechanical multistability in a high-Q torsion balance, with up to 23 stable trapping regions due to optical forces.

Findings

Up to 23 stable trapping regions observed.

Hysteresis behavior between trapping positions.

Potential for stochastic resonance to improve gravity measurements.

Abstract

We observe the opto-mechanical multistability of a macroscopic torsion balance oscillator. The torsion oscillator forms the moving mirror of a hemi-spherical laser light cavity. When a laser beam is coupled into this cavity, the radiation pressure force of the intra-cavity beam adds to the torsion wire's restoring force, forming an opto-mechanical potential. In the absence of optical damping, up to 23 stable trapping regions were observed due to local light potential minima over a range of 4 micrometer oscillator displacement. Each of these trapping positions exhibits optical spring properties. Hysteresis behavior between neighboring trapping positions is also observed. We discuss the prospect of observing opto-mechanical stochastic resonance, aiming at enhancing the signal-to-noise ratio (SNR) in gravity experiments.