Tunable coupling regimes of silicon microdisk resonators using MEMS actuators.

Tunable coupling regimes of a silicon microdisk resonator controlled by MEMS (microelectromechanical system) actuation are demonstrated for the first time. By varying the gap spacing between the waveguide and the disk, this microresonator can dynamically operate in either under-, ciritcal or over-coupling regime. The waveguide transmittance is suppressed by 30 dB in critical coupling, and the quality factor of the microdisk is measured to be as high as 10(5). Additionally, the microdisk presents tunable group delay from 27 ps to 65 ps, and tunable group velocity dispersion from 185 ps/nm to 1200 ps/nm. Waveguides, microdisks and actuators are all integrated on a silicon-on-insulator (SOI) substrate. This compact device exhibits the promise to construct resonator-based reconfigurable photonic integrated circuits.