Careful control of the optical paths in the structure ensures that light from each input constructively interferes in exactly the right output. The researchers demonstrated that light circulation (bandwidth, isolation ratio, noise performance and circulation direction) could be actively tuned through modifying the frequency and power of the control laser, allowing light circulation to be turned on and off. On a four-port circulator, they experimentally demonstrated 10dB isolation and under 3dB insertion loss in all relevant channels.
Such optomechanical resonators could not only be used for reconfigurable integrated nanophotonic circuits but also to develop enhanced positioning systems, since reversibly, any changes in movements of the resonator could be detected by altered light paths and signal attenuation. Such high-precision optical inertial units could find applications deep underground where GPS signal are out of reach, and to navigate deep underwater.
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