Alumina coating for dispersion management in ultra-high Q microresonators

• DOI: 10.1063/5.0028839
• Publication Date: 2020-11-20T15:10:08Z
• Authors: Marvyn Inga; Laís Fujii; José Maria C. da ...; João Henrique Qui...; Andre Santarosa F...; Francisco C. Marques; Thiago P. Mayer A...; Gustavo Wiederhecker
• Keywords: Group velocity; Group delay dispersion; Optical coating

Silica optical microspheres often exhibit ultra-high quality factors, yet their group velocity dispersion, which is crucial for nonlinear optics applications, can only be coarsely tuned. We experimentally demonstrate that group-velocity dispersion of a silica microsphere engineered by coating it with conformal nanometric layers alumina preserving its factors (∼107) at telecom wavelengths. Using the atomic layer deposition technique dielectric coating, ensures nm-level thickness control, we not achieve fine tailoring but also maintain low surface roughness and material absorption to ensure loss. Numerical simulations supporting our experimental results show promising precise tuning dispersion. As an application, generation Kerr frequency combs, showing coatings sustain high intensities necessary phenomena.