Dielectric metasurfaces have shown prominent applications in nonlinear optics due to strong field enhancement and low dissipation losses at the nanoscale. Chalcogenide glasses are one of the promising materials for the observation of nonlinear effects due to their high intrinsic nonlinearities. Here, we demonstrate, experimentally and theoretically, that significant second harmonic generation can be obtained within amorphous chalcogenide based metasurfaces by relying on the coupling between lattice and particle resonances. We further show that the high quality factor resonance at the origin of the second harmonic generation can be tuned over a wide wavelength range using a simple and versatile fabrication approach. The measured second harmonic intensity is orders of magnitude higher than that from a deposited chalcogenide film, and more than three orders of magnitude higher than conventional plasmonic and Silicon-based structures. Fabricated via a simple and scalable technique, these all-dielectric architectures are ideal candidates for the design of flat non-linear optical components on flexible substrates.
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