Second harmonic generation in glass-based metasurfaces using tailored surface lattice resonances

Abstract

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 thanks to their high intrinsic nonlinearities. Here, we demonstrate, experimentally and theoretically, that significant second harmonic generation (SHG) can be obtained within amorphous Selenium (Se)-based chalcogenide metasurfaces by exploiting the coupling between lattice and particle resonances. We further show that the high-quality factor resonance at the origin of the SHG 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 dewetted Se film consisting of random Se nanoparticles. The achieved conversion efficiency in the resonance region is of the order of 10−6 which is comparable with direct bandgap materials and at least two orders of magnitude higher than that of conventional plasmonics- and Si-based structures. Fabricated via a simple and scalable technique, these all-dielectric architectures are ideal candidates for the design of flat nonlinear optical components on flexible substrates.

Nanoimprinting Solution-Derived Barium Titanate for Electro-Optic Metasurfaces

“…This lattice mode hybridizes with the Mie resonances of the individual unit cells, forming sharp Fano-shaped resonances. These resonances shift with the geometrical parameters r and p , leading to the high theoretical and experimental Q -factors observed . The simulations confirm not only the origin of the resonance but also fully reproduce the measured spectrum.…”

“…These resonances shift with the geometrical parameters r and p, leading to the high theoretical and experimental Q-factors observed. 20 The simulations confirm not only the origin of the resonance but also fully reproduce the measured spectrum.…”

“…17 Solution-based BTO materials are compatible with costefficient and large-scale nanofabrication techniques, such as soft-nanoimprint lithography (SNIL), 18 which have been successfully implemented to produce nonlinear metasurfaces. 19,20 However, restrictions in nanoparticle packing density limit the refractive index contrast needed for efficient optical nanostructures. Sol−gel derived barium titanate, with higher filling fractions of the imprint mold and thus lower structures' porosity, is more suitable for high-quality nanoscale photonic applications than nanoparticles.…”

Demonstration of a Plasmonic Nonlinear Pseudodiode

“…Nevertheless, this limitation can be partially overcome by virtue of the field enhancement associated with surface plasmon resonances at metal surfaces. Thus, various SHG enhancement schemes were proposed for plasmonic metasurfaces, based on multipolar resonances, 30−36 plasmonic lattice resonances, 37,38 and even light-induced centrosymmetry breaking. 39 On the other hand, bianisotropic metasurfaces allow engineering the polarization response to realize highly efficient refraction devices through the combination of electric and magnetic effects.…”

“…Nevertheless, this limitation can be partially overcome by virtue of the field enhancement associated with surface plasmon resonances at metal surfaces. Thus, various SHG enhancement schemes were proposed for plasmonic metasurfaces, based on multipolar resonances, − plasmonic lattice resonances, , and even light-induced centrosymmetry breaking …”