Patent ID: 7801189

Claim:
A photonic device, comprising: a laser that is tunable and produces a laser beam at a laser frequency; an optical resonator exhibiting an electro-optic effect and structured to support whispering gallery modes circulating in the optical resonator in two mutually orthogonal polarizations and being optically coupled to the laser to receive a portion of the laser beam into the optical resonator; a laser locking mechanism to lock the laser frequency with respect to a whispering gallery mode resonance of the optical resonator; an evanescent optical coupler that evanescently couples the laser beam into the optical resonator and evanescently couples the light inside the optical resonator out of the optical resonator to produce resonator output light; electrodes formed on the optical resonator to apply a modulation control signal to effectuate an optical modulation of light based on the electro-optic effect; an optical detector to receive a portion of light from the laser that does not enter the optical resonator and at least a portion of the resonator output light; a polarization control mechanism to control polarizations of the portion of light from the laser that does not enter the optical resonator and the portion of the resonator output light to allow light in the two mutually orthogonal polarizations to interfere at the optical detector to produce a single modulation sideband corresponding to one of the two mutually orthogonal polarizations; and a feedback circuit coupled between the optical detector and the electrodes to receive a detector output from the optical detector and to produce the modulation control signal at a tunable modulation frequency.