One of the greatest challenges of non-linear optics is associating extreme light confinement and chromatic dispersion control in materials with high nonlinear susceptibility and low optical absorption.
Microfabrication maturity allows us to manufacture monolithic optical waveguides and microcavities with ultra-high quality factors (Q > 10⁶) and high nonlinear coefficients. This combination makes nonlinear nanophotonics highly competitive with traditional optical fiber technologies.
At LPD, ultra-high Q microcavities are used to explore electronic response non-linear effects including third-harmonic generation (THG), four-wave mixing (FWM), and Kerr optical frequency comb generation.
Group-velocity dispersion (GVD) is crucial for nonlinear optics applications. In silica microspheres and wedge microcavities, natural material dispersion limits nonlinear efficiency. We demonstrate nanometric conformal coatings (e.g. alumina Atomic Layer Deposition) and geometrical wedge tailoring to precisely engineer GVD while preserving Q factors ~10⁷ at telecom wavelengths.