Electrical thermo-optic tuning of ultrahigh-$Q$ microtoroid resonators

The ability to tune resonant frequency in optical microcavities is an essential feature for many applications. Integration of electrical-based tuning as part of the fabrication process has been a key advantage of planar microresonant devices. Until recently, the combination of these features has not been available in devices that operate in the ultrahigh-$Q$ regime where device quality factors $(Q)$ can exceed 100 million. In this letter, we demonstrate an electrically tunable resonator on a chip with ultrahigh-quality factors. Futhermore, the devices have demonstrated tuning rates in excess of $85GHz∕V2$ and are capable of tuning more than $300GHz$⁠.