Hydroxyl ion absorption in on-chip high-Q resonators
Abstract
Thermal silica is a common dielectric used in all-silicon photonic circuits. Additionally, bound hydroxyl ions (Si-OH) can provide a significant component of optical loss in this material on account of the wet nature of the thermal oxidation process. A convenient way to quantify this loss relative to other mechanisms is through OH absorption at 1380 nm. Here, using ultra-high-quality factor (Q-factor) thermal-silica wedge microresonators, the OH absorption loss peak is measured and distinguished from the scattering loss baseline over a wavelength range from 680 nm to 1550 nm. Record-high on-chip resonator Q-factors are observed for near-visible and visible wavelengths, and the absorption limited Q-factor is as high as 8 billion in the telecom band. Hydroxyl ion content level around 2.4 ppm (weight) is inferred from both Q measurements and by secondary ion mass spectroscopy (SIMS) depth profiling.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 23, 2023
- Source ID
- 10.1364/ol.492067
Entities
People
- Hao-Jing Chen
- Henry A. Blauvelt
- Jin-yu Liu
- Kellan Colburn
- Kerry Vahala
- Lue Wu
- Maodong Gao
Organizations
- California Institute of Technology
- Defense Advanced Research Projects Agency