Published in the Research School of Physics Event Horizon
Vol45 Issue46 16–20 November 2020
In the recent paper <Communications Physics> 3, 197 (2020), Jinyong Ma et al. from DQS experimentally investigated the dynamics of a free-standing mirror acting as the top reflector of a vertical optical cavity. The milligram-scale mirror is expected to be levitated by the light inside the cavity when the optical radiation pressure force balances the mirror’s gravitational force. To reach the regime of levitation, the optical intensity of the intracavity light field approaches intensities higher than that experienced by LIGO. In this system, they identified three distinct physics effects: excitation of acoustic vibrations, expansion due to thermal absorption of light, and partial lift-off of the mirror due to radiation pressure force. They also managed to modify the mirror's response with active feedback control to improve the overall stability of the system. With the analysis and modeling drawn from these investigations, they showed a route towards the realization of stable and coherent optical levitation.