Low-threshold parametric oscillation in organically modified microcavities.

Coherent frequency generators are an enabling platform in basic science and applied technology. Originally reliant on high-power lasers, recently comb generation has been demonstrated in ultrahigh- Q microcavities. The large circulating intensity within the cavity results in strong light-matter interaction, giving rise to Kerr parametric oscillations for comb generation. However, the comb generation threshold is limited by competing nonlinear effects within the cavity material and low intrinsic material Kerr coefficients. We report a new strategy to fabricate near-infrared frequency combs based on combining high- Q microcavities with monomolecular layers of highly nonlinear small molecules. The functionalized microcavities demonstrate high-efficiency parametric oscillation in the near-IR and generate primary frequency combs with 0.88-mW thresholds, improving optical parametric oscillation generation over nonfunctionalized devices by three orders of magnitude. This organic-inorganic approach enables otherwise unattainable performance and will inspire the next generation of integrated photonic device platforms.