Department of Physics and Astronomy, The University of Kansas , Lawrence, Kansas 66045, United States.
ACS Appl Mater Interfaces. 2014 Jan 8;6(1):314-8. doi: 10.1021/am4042542. Epub 2013 Dec 16.
We observe optical third-harmonic generation in atomically thin films of MoS2 and deduce effective third-order nonlinear susceptibilities on the order of 10(-19) m(2)/V(2), which is comparable to that of commonly used semiconductors under resonant conditions. By measuring the susceptibility as a function of light wavelength, we find significant enhancements of the susceptibility by excitonic resonances. The demonstrated third-harmonic generation can be used for nonlinear optical identification of MoS2 atomic layers with high contrast, better distinguishing power of multilayers, and less restrictions to substrate selections. The size of the third-order nonlinear susceptibility suggests feasibility of exploring other types of third-order nonlinear optical effects of MoS2 two-dimensional crystals.
我们在原子级薄的 MoS2 薄膜中观察到了光的三次谐波产生，并推导出了有效三阶非线性介电常数约为 10(-19) m(2)/V(2)，在共振条件下与常用半导体相当。通过测量介电常数随光波长的变化，我们发现激子共振显著增强了介电常数。所展示的三次谐波产生可用于具有高对比度的 MoS2 原子层的非线性光学识别，对多层的分辨能力更强，对衬底选择的限制也更少。三阶非线性介电常数的大小表明探索 MoS2 二维晶体的其他类型三阶非线性光学效应是可行的。
