二阶非线性光学效应源于电子势函数的非谐性，可实现激光的频率转换，被广泛应用于基 础科学研究和现代激光技术。单层过渡金属硫族化合物具有极大的二阶非线性系数，作为基础单 元实现高效的非线性光学响应潜力巨大。如何保持单层材料的极大非线性系数，扩展材料厚度及 响应频段，提升非线性响应，是重要挑战。本文主要介绍了基于单层过渡金属硫族化合物的二阶 非线性光学效应的调控，包括单层过渡金属硫族化合物的频率依赖及不同对称性相的多层堆叠等， 并总结了过渡金属硫族化合物非线性光学效应的应用前景。

Second-order nonlinear optics is a crucial technique for light frequency conversion with broad applications in scientific research and technological advancements. Monolayer transition metal dichalcogenides exhibit extraordinarily high second-order nonlinear susceptibilities, indicating their significant potential for efficient nonlinear optical response. Maintain the giant nonlinear coefficient of monolayer, expand material thickness and frequency response region, and improve nonlinear response is an important challenge. This paper presents an overview of the regulation of second-order nonlinear optical effects based on monolayer transition metal dichalcogenides. We discuss the frequency dependence of monolayer transition metal dichalcogenides, as well as multi-layer stacking of different symmetric phases. Additionally, we summarize the potential applications of their nonlinear optical effects.