Enhancement of the Second-Harmonic Generation Based on the Multipole Coupling Effect in 3R-MoS2 Metasurface

The emergence of new optical materials with strong nonlinearity, including recently synthesized 3R polytypes of layered van der Waals materials with broken central symmetry of monolayer arrangement, sets a new trend in the development of nonlinear and quantum nanophotonics. A model of the second harmonic generation in nanostructures based on the 3R polytype of molybdenum disulfide pumped within the telecommunication wavelength range has been examined in this work. To further increase the generation efficiency and second harmonic intensity, a new mechanism of multipole coupling in a dielectric metasurface is used, enabling the excitation of high- Q quasi-trapped modes without breaking the structural symmetry of the system. Localization and enhancement of the near field in the plane of the optimized 3R-MoS 2 metasurface pumped at a wavelength of 1.55 μm have made it possible to obtain a second harmonic peak with a FWHM of 0.98 nm and the intensity significantly exceeding the intensity of the second harmonic from the same metasurface, but at a wavelength shifted from resonance conditions.