Mechanical oscillation and cooling actuated by the optical gradient force.
In this work, we combine the large per-photon optical gradient force with the sensitive feedback of a high quality factor whispering-gallery microcavity. The cavity geometry, consisting of a pair of silica disks separated by a nanoscale gap, shows extremely strong dynamical backaction, powerful enough to excite coherent oscillations even under heavily damped conditions (mechanical Q approximately 4). In vacuum, the threshold for regenerative mechanical oscillation is lowered to an optical input power of only 270 nW, or roughly 1000 stored cavity photons, and efficient cooling of the mechanical motion is obtained with a temperature compression factor of nearly 14 dB with an input optical power of only 11 microW.
Thomas J. Watson, Sr., Laboratory of Applied Physics, California Institute of Technology, Pasadena, California 91125, USA.
Qiang
Q
Lin
Jessie
J
Rosenberg
Xiaoshun
X
Jiang
Kerry J
KJ
Vahala
Oskar
O
Painter
D055095:Optics and Photonics / Q000295:instrumentation / Q000379:methods*