Khazaee Sara, Peschel Ulf
Opt Express. 2024 Feb 12;32(4):5088-5094. doi: 10.1364/OE.506357.
Two-dimensional transition metal dichalcogenides have shown large second-order nonlinear responses due to their broken crystal inversion symmetry. However, their nonlinear interaction with light is restricted to an atomically thin layer. Placing a sheet of transition metal dichalcogenides on a resonant metasurface enhances the field interacting with the nonlinear material thus compensating for this shortcoming. But, it remains a challenge to tune resonances such, that they coincide with fundamental and second harmonic frequencies simultaneously. Here we demonstrate two independent methods to achieve that goal and numerically illustrate our findings for a MoS layer combined with silicon nitride photonic crystals. We numerically demonstrate 20-fold and 170-fold enhancement of second-harmonic generation compared with a design based on a single resonant structure. Although we focus on that specific configuration our approach can likewise be applied to other dielectrics combined with highly nonlinear 2D materials.
二维过渡金属二硫属化物由于其晶体反演对称性破缺而表现出较大的二阶非线性响应。然而，它们与光的非线性相互作用仅限于原子级薄的层。将一片过渡金属二硫属化物放置在共振超表面上可增强与非线性材料相互作用的场，从而弥补这一缺点。但是，调谐共振使其同时与基频和二次谐波频率重合仍然是一个挑战。在这里，我们展示了两种独立的方法来实现这一目标，并通过数值模拟说明了我们对于结合了氮化硅光子晶体的MoS层的研究结果。与基于单一共振结构的设计相比，我们通过数值模拟证明了二次谐波产生增强了20倍和170倍。尽管我们专注于该特定配置，但我们的方法同样可应用于与高非线性二维材料结合的其他电介质。
