Sensing dispersive and dissipative forces by an optomechanical cavity

We experimentally study an optomechanical cavity that is formed between a mechanical resonator, which serves as a movable mirror, and a stationary on-fiber dielectric mirror. A significant change in the behavior of the system is observed when the distance between the fiber's tip and the mechanical resonator is made smaller than about $1\ \mu \text{m}$ . The combined influence of Casimir force, Coulomb interaction due to trapped charges, and optomechanical coupling is theoretically analyzed. The comparison between experimental results and theory yields a partial agreement