Fano-resonant silicon photonic crystal slab for efficient third-harmonic generation

Strong light–matter interactions in resonant photonic nanostructures open up opportunities for enhancing nonlinear responses. In this work, by applying Fano resonances, we experimentally demonstrate efficient third-harmonic generation (THG) obtained with 2D silicon photonic crystal slabs (PCSs) thanks to the field enhancement in the dielectric layer. A 160-fold enhancement of THG is observed in the silicon PCS compared to the unpatterned silicon film. Through slightly changing the radius of the PCS, tunable THG on a single chip is obtained, paving a way for the optical manipulation of harmonic generation.