Monolithically integrated waveguide-coupled silica microtoroids

We report on the design and fabrication of a new type of microtoroid high-Q silica resonators monolithically coupled to on-chip silicon nanowire waveguides. In order to enable monolithic waveguide coupling, the microtoroid geometry is inverted such that the resonator is formed by thermal reflow at the circumference of a hole etched in a suspended SiO₂ membrane. This configuration is shown to be conducive to integration with a fully functional Silicon Photonics technology platform.