Silicon-based monolithically integrated whispering-gallery mode resonators

摘要

We report on the realization and characterization of a silicon-based integrated optical platform which implements a vertical coupling scheme between a Whispering-gallery type microresonator and a buried dielectric waveguide. The vertical coupling allows for the separation of the resonator and the waveguide into different planes, which enables the realization of the optical components in different materials/thicknesses. The high optical quality of this micro-optical system follows from the accurate planarization of the waveguide topography, which is achieved by multiple depositions-and-reflows of a borophosphosilicate glass over strip waveguides. Importantly, we demonstrate the feasibility of our approach for wafer-scale mass fabrication of freestanding planar resonators suspended in air and coupled to integrated bus waveguides. This opens the door for the realization of stable all-integrated resonator systems and it has the potential to substitute todays complicated fiber-taper coupling schemes.