Hybrid Dielectric Metasurfaces for Enhancing Second-Harmonic Generation in Chemical Vapor Deposition Grown MoS₂ Monolayers

Abstract

The coupling of two-dimensional materials with optical metasurfaces is a promising avenue to enhance the advantageous properties of both platforms. Here we integrate an ultrathin monolayer of the transition metal dichalcogenide (TMD) MoS2, grown by chemical-vapor deposition, with a silicon metasurface, to obtain a hybrid system with enhanced nonlinear response. To this end, we utilize a metasurface exhibiting resonances with high quality factors, which provides increased optical fields. Using the nonlinearity of the TMD monolayer, these resonantly enhanced fields enable more efficient nonlinear frequency conversion. In particular, we experimentally observe an enhanced efficiency of second-harmonic generation in our hybrid structure. By comparing second-harmonic generation using different photonic resonances, we furthermore identify optimized conditions for the spatial distribution of the local optical fields to maximize the nonlinear response. Our results enable the precise design of hybrid structures consisting from TMDs and metasurfaces for future applications.

Nonlinear Exciton‐Mie Coupling in Transition Metal Dichalcogenide Nanoresonators

“…Taking into account that only 25% of the pump power hits the nanodisk surface, the actual SH efficiency can be estimated as 2 $$\times$$ 10$${}^{-6}$$ W$${}^{-1}$$. The observed values of the gain and conversion coefficients are comparable with the ones obtained using optomechanical amplification of the SH signal, [ 48 ] as well as the combination of a MoS 2 monolayer with a micro‐cavity [ 49 ] and bound state in the continuum [ 50 ] systems. Also, the demonstrated efficiency is two orders of magnitude larger than the SH conversion efficiency for a MoS 2 metasurface with Mie resonances [ 51 ] in the absence of absorption at the SH frequency.…”

Optical Harmonic Generation in 2D Materials

“…[ 255 ] Franz et al. [ 261 ] found 35‐folds enhancement in SHG on multilayer MoS 2 coupled with a Si metasurface as compared to multilayer MoS 2 on SiO 2 . Chen et al.…”

Polarization-controlled dynamically switchable high-harmonic generation from all-dielectric metasurfaces governed by dual bound states in the continuum

“…Finally, it is worth pointing out that the strategy and structure here are rather general, and can be extended for the selective enhancement of other nonlinear effects at alternative wavelengths via physical scalability 64,65 . One example that comes to mind may be the polarization-controlled harmonic generation and sum-frequency mixing in 2D materials [66][67][68][69][70] .…”