High-Finesse Silica Microdisk Optical Resonators on a Silicon Chip

On-chip optical microresonators are important for nonlinear optics, cavity quantum electrodynamics, and optical sensing, where both high finesse and high quality (Q) factors are essential yet difficult to achieve simultaneously. Here, we demonstrate chip-based silica optical microresonators fabricated by standard dry-etching processes, achieving finesses as high as 6.06 × 10⁵, 5.03 × 10⁵, 3.78 × 10⁵, and 2.72 × 10⁵ for microdisks with diameters of 100 μm, 200 μm, 300 μm, and 400 μm, respectively. To the best of our knowledge, the finesse achieved here is the highest among chip-based silica microdisk optical resonators. We also demonstrate a record quality factor of 3.3 × 10⁸ for dry-etched silica microdisks on a silicon chip. To further investigate the nonlinear optical properties of the fabricated devices, we also realize a low-threshold (52.7 μW) optical parametric oscillation (OPO) based on a 200 μm diameter microdisk microresonator. These results pave the way for chip-based, dry-etched silica microdisks as a promising platform for Kerr soliton combs and other low-power nonlinear photonic applications.