Design and Fabrication of Ultrahigh Q Chip-Based Silica WGM Micro-resonators for Single-Atom Cavity-QED

Of the many applications of whispering-gallery mode (WGM) microresonators, single-atom cavity quantum electrodynamics (cavity-QED) poses the most extreme demands on mode-volume, dimensions and quality factor (Q). Here we present the procedure for the fabrication of chip-based, small mode-volume, ultrahigh Q silica WGM microresonators, designed for single-emitter cavity-QED. We demonstrate microresonators at varying geometries, from toroidal to micro-spheres, yielding ultrahigh-qualities as high as 1.7×10⁸ at 780nm. We present a comprehensive theoretical model that allows tailoring the fabrication process to attain the desired microresonator geometry.