OH absorption in on-chip high-Q resonators

Abstract

Thermal silica is a common dielectric used in all silicon-photonic circuits. And 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-Q thermal-silica wedge microresonators, the OH absorption loss peak is measured and distinguished from the scattering loss base line 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. OH ion content level around 2.4 ppm (weight) is inferred from both Q measurements and by Secondary Ion Mass Spectroscopy (SIMS) depth profiling.

arXiv comment4 pages, 3 figures

References in corpus (4)

• Hertz-linewidth semiconductor lasers using CMOS-ready ultra-high-$Q$ microresonators
• 422 Million Q Planar Integrated All-Waveguide Resonator with a 3.4 Billion Absorption Limited Q and Sub-MHz Linewidth
• Probing material absorption and optical nonlinearity of integrated photonic materials
• Fabrication of Ultra-High Q Silica Microdisk Using Chemo-Mechanical Polishing

Cited by in corpus (4)

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• Absorption loss and Kerr nonlinearity in barium titanate waveguides
• Silicon photonic paper-clip spiral delay lines with ultra-low delay loss of 0.5 dB/ns