Observation of optomechanical multistability in a high-Q torsion balance oscillator (vol 77, art no 031802, 2008)

We observe the optomechanical multistability of a macroscopic torsion balance oscillator. The torsion oscillator forms the moving mirror of a hemispherical laser light cavity. When a laser beam is coupled into this cavity, the radiation pressure force of the intracavity beam adds to the torsion wire's restoring force, forming an optomechanical 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 μm 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 optomechanical stochastic resonance, aiming at enhancing the signal-to-noise ratio (SNR) in gravity experiments. © 2008 The American Physical Society.