422 Million intrinsic quality factor planar integrated all-waveguide resonator with sub-MHz linewidth

We report for the first time an optical resonator made from a chip-scale waveguide platform has achieved an intrinsic Q greater than 400 million and a linewidth below 1 MHz, through the groundbreaking resonator design and fabrication, the analysis of optical loss mechanisms, and the characterization of the waveguide material composition. We believe this multidisciplinary and high-quality research work represents significant advance the physical and optical sciences.