Ling Haonan, Tang Yuankai, Tian Xinyu, Shafirin Pavel, Hossain Mozakkar, Vabishchevich Polina P, Harutyunyan Hayk, Davoyan Artur R
Mechanical and Aerospace Engineering Department, University of California, Los Angeles, California 90095, United States.
Mechanical and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816, United States.
Nano Lett. 2025 Jun 11;25(23):9229-9236. doi: 10.1021/acs.nanolett.5c00952. Epub 2025 May 26.
Efficient nonlinear wave mixing is of paramount importance for a wide range of applications. However, weak optical nonlinearities pose significant challenges for accessing nonlinear light-matter interaction in compact systems. Here, we experimentally study second harmonic generation in deeply subwavelength 3R-MoS metasurfaces (<λ/13 thick). Our measurements, supported by theoretical analysis, reveal a complex interplay and coupling between geometric resonances, optical extinction, and exciton-driven strong nonlinear susceptibility dispersion. We further demonstrate >150-fold enhancement in second harmonic signal at 740 nm mediated by the A exciton resonance. Additionally, our theoretical studies predict an enhancement of more than 10 in second harmonic generation in <100 nm thick structures exhibiting bound states in the continuum resonance. These findings provide insight into accessing and harnessing the unprecedented 3R-MoS nonlinearities at a subwavelength scale, paving the way to ultracompact nonlinear photonic devices.
高效的非线性波混频对于广泛的应用至关重要。然而，弱光学非线性给在紧凑系统中实现非线性光与物质相互作用带来了重大挑战。在此，我们通过实验研究了深度亚波长3R - MoS超表面（厚度<λ/13）中的二次谐波产生。我们的测量结果在理论分析的支持下，揭示了几何共振、光学消光和激子驱动的强非线性极化率色散之间复杂的相互作用和耦合。我们进一步证明，在A激子共振介导下，740 nm处的二次谐波信号增强了150倍以上。此外，我们的理论研究预测，在厚度小于100 nm且表现出连续谱束缚态共振的结构中，二次谐波产生增强超过10倍。这些发现为在亚波长尺度上获取和利用前所未有的3R - MoS非线性提供了见解，为超紧凑非线性光子器件铺平了道路。
