MoS2 monolayer coupled to a multi-resonant dielectric metasurface exhibiting enhanced second-harmonic generation

Abstract

We experimentally analyze enhancement of second-harmonic generation from CVD-grown MoS2 monolayers coupled to a Si metasurface exhibiting different resonances and reveal how different resonant fields influence the nonlinear conversion efficiency.

Parametric Nonlinear Optics with Layered Materials and Related Heterostructures

“…[223] Löchner et al, produced a hybrid system of a 1L TMD and a metasurface of periodic arrays of Si nanoresonators. [224] Here, a 35-fold SHG conversion efficiency enhancement was observed due to the asymmetry of designed meta-atoms, which support a Fano resonance with high Q-factor. The authors have further studied the conditions of the local field distributions that maximize the SHG efficiency.…”

“…A first widely used approach to enhance light-matter interaction in 2D materials is to combine them with nanostructured substrates such as resonant dielectric and plasmonic metasurfaces. [216,[220][221][222][223][224] In the case of dielectric metasurfaces, three orders of magnitude SHG enhancement was demonstrated in TMDs by Bernhardt et al, by combining a 1L WS 2 with an engineered asymmetric silicon substrate (Figure 10a), which supports high-Q mode in the form of quasi-BIC states (bound states in the continuum [225] ) at the FF. [223] Löchner et al, produced a hybrid system of a 1L TMD and a metasurface of periodic arrays of Si nanoresonators.…”

Second Harmonic Generation Control in 2D Layered Materials: Status and Outlook

“…All these features enable dielectric nanostructures ideal candidates for future compact, lowloss, high-efficient, and large-area integrated nonlinear photonic devices. [352][353][354][355] So far, various resonant dielectric nanostructures including photonic crystals (PCs), [95] waveguides, [324] NPs, [356,357] metasurfaces, [94,325,[358][359][360][361] and patterned 2DLMs [362] have been adopted to greatly enhance the SHG conversion efficiency in 2DLMs.…”

Quasi‐Bound States in the Continuum Enhanced Second‐Harmonic Generation in Thin‐Film Lithium Niobate

“…When considering free-space coupling with pump beams impinging upon the nonlinear device along the film thickness direction, the characteristic distance of interactions can be at the sub-wavelength scale. In this regime, the nonlinear conversion can be dramatically promoted via the recently emerged concepts of anapole [30][31][32] and bound states in the continuum (BICs) [33][34][35][36][37][38][39][40] in nanophotonics. The term anapole refers to a configuration of electromagnetic fields with zero net dipolar radiation.…”

“…Particularly, spatially extended BIC modes in 2D periodic arrays are of special interest for enhancing nonlinear optical processes, as they allow the thin-film volume of nonlinear materials to be well exploited. [33][34][35][36][37][38][39] Furthermore, strict phase-matching is not required in such thin resonant nanostructures. In practice, BICs degrade into quasi-BICs with a limited yet still high quality (Q) factor, due to structure imperfections and finite extent, or by breaking the in-plane inversion symmetry intentionally.…”