Proposal and Fabrication of an Electrooptically Controlled Multimode Microresonator for Continuous Fast-to-Slow Light Tuning

We propose a scheme to utilize a multimode microdisk resonator in silicon controlled through free-carrier injection for continuous fast-to-slow light tuning. Two nearby resonant modes are employed, i.e., undercoupling and overcoupling. The optical properties of a device are analytically investigated considering the resonance spacing, bandwidth, and density change of free carriers. Pulse propagation simulations are implemented, and the pulse delay/advance is studied for wavelengths between the two resonances. As the density of injected free carriers increases, a continuous transition from fast to slow light occurs for a range of wavelengths. Consequently, a microdisk resonator in silicon is experimentally realized with the desired two resonances, exhibiting electrooptical tuning with a fast response. The experimental results agree well with the simulation in power transmission, and the tunable time delay and advance are also predicted.