Tailoring the quality factors and nonlinear response in hybrid plasmonic-dielectric metasurfaces.

Plasmonic nanoantennas and metamaterials concentrate optical energy into nanometric volumes strongly enhancing the light-matter interaction. This makes them promising platforms for optical sensing, nonlinear effects and quantum optics. However, absorption losses and radiative damping result in broad, low quality factor (Q) resonances of plasmonic systems that significantly limit their performance. Here, we develop a hybrid plasmonic/dielectric metasurface that can simultaneously achieve high Q and large field enhancement values in the near infrared by forming a hybridized mode between the nanoantennas' plasmonic mode and the photonic waveguide mode of Si device layer. The tunability of the modes and quality factors of our platform allows us to study the effect of the geometric parameters on the optical properties of the metasurface. We demonstrate that the strongest near field enhancement and nonlinear signal generation can be achieved by balancing the high Q factors and in-coupling efficiency in hybrid resonators.