Nonlinear Fano-Resonant Dielectric Metasurfaces

Strong nonlinear light–matter interaction is highly sought-after for a variety of applications including lasing and all-optical light modulation. Recently, resonant plasmonic structures have been considered promising candidates for enhancing nonlinear optical processes due to their ability to greatly enhance the optical near-field; however, their small mode volumes prevent the inherently large nonlinear susceptibility of the metal from being efficiently exploited. Here, we present an alternative approach that utilizes a Fano-resonant silicon metasurface. The metasurface results in strong near-field enhancement within the volume of the silicon resonator while minimizing two photon absorption. We measure a third harmonic generation enhancement factor of 1.5 × 105 with respect to an unpatterned silicon film and an absolute conversion efficiency of 1.2 × 10–6 with a peak pump intensity of 3.2 GW cm–2. The enhanced nonlinearity, combined with a sharp linear transmittance spectrum, results in transmission modul...