局域场增强的二维材料非线性光学性能调控与应用

二维材料具有块体材料不具备的独特光电性质，引起了国内外科学家强烈的研究兴趣。其中单层过渡金属硫化物(如二硫化钼、二硒化钨)，由于结构的不对称性和相对较大的二阶非线性极化率(~0.1 nm/V，泵浦光1550 nm)，在超薄非线性光电器件中产生了巨大应用前景。然而原子层的厚度导致二维材料与光作用距离短（~0.7 nm）、非线性转化率低（<0.1%），这将阻碍二维材料的产业化应用。申请人将以二维过渡金属硫化物和镓硫族化物为研究对象，利用金属或硅光学结构产生的强局域场来提高它们的二阶（二次谐波）和三阶非线性性能（双光子荧光），以及非线性信号的谷极化效应；分析影响非线性性能的各种因素，研究金属或硅结构与二维材料的相互作用机理，提出增强非线性性能的机理模型，并制备基于局域场增强的二维材料非线性电光调制器和红外光电探测器。该项目将推动非线性光学在二维材料领域的基础研究，也将促进二维材料的光电器件应用。

2D materials have attracted scientists tremendous interests, owing to their unique properties that are absent in their bulk counterparts. Monolayer 2D materials such as transition metal dichalcogenides (MoS2 and WSe2) have great potential in the applications of ultrathin nonlinear optoelectronic devices, due to their breaking inversion symmetry and relatively large second-order susceptibility (~0.1 nm/V at the pump of 1550 nm). However, the atomically thin thickness results in short light-matter interaction length (~0.7 nm) and low nonlinear conversion efficiency (<0.1%)， which may block their practical applications. On the basis of studying the 2D transition metal dichalcogenides and gallium monochalcogenides, the applicant will use metal nanostructures and silicon cavities that support concentrated localized optical field, to enhance the nonlinear optical properties such as second harmonic generation and two-photon photoluminescence. After systemically investigating the factors that influence the nonlinear properties and revealing the interaction mechanisms between nanostructures (cavities) and 2D materials, the applicant will use make nonlinear devices of electrically tuned optical modulators and infrared photodetectors. This project will be beneficial for the fundamental research of nonlinear optics in 2D materials and will promote the development of 2D materials in nonlinear devices.