Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Science , Beijing 100190, China.
University of Chinese Academy of Sciences , Beijing 100049, China.
ACS Nano. 2018 Jan 23;12(1):689-696. doi: 10.1021/acsnano.7b07823. Epub 2018 Jan 5.
Two-dimensional (2D) layered materials, with large second-order nonlinear susceptibility, have received much scientific interest due to their potential applications in nonlinear optical devices. However, the atomic thickness of 2D layered materials leads to poor field confinement and weak light-matter interaction at the nanoscale, resulting in low nonlinear conversion efficiency. Here, 2D pyramid-like multilayer (P-multilayer) layered structures are fabricated for efficient edge second-harmonic generation (SHG) based on the enhanced light-matter interaction in whispering-gallery mode (WGM) cavities. The P-multilayer 2D layered materials, where the basal planes shrink gradually from the bottom to the top layers, exhibit efficient edge SH radiation due to the partial destructive interference of nonlinear polarizations between the neighboring atomic layers. Moreover, the well-defined 2D plate-like triangle morphology of P-multilayer WS forms a WGM resonance cavity, which results in enhanced light-matter interaction and thus the enhancement of edge SHG, which can be further enhanced by hybridizing the WGM mode with plasmonics. These results provide enlightenment for the construction of specific structures for efficient nonlinear processes.
二维（2D）层状材料具有较大的二阶非线性极化率，由于其在非线性光学器件中的潜在应用而受到广泛关注。然而，2D 层状材料的原子厚度导致在纳米尺度上的场限制较差和光物质相互作用较弱，从而导致低的非线性转换效率。在这里，基于 whispering-gallery 模式（WGM）腔中的增强的光物质相互作用，制造了 2D 金字塔形多层（P-多层）层状结构，以实现高效的边缘二次谐波产生（SHG）。底部到顶层逐渐收缩的 P-多层 2D 层状材料由于相邻原子层之间的非线性极化之间的部分相消干涉，表现出高效的边缘 SH 辐射。此外，P-多层 WS 的明确的 2D 板状三角形形态形成了 WGM 共振腔，这导致了增强的光物质相互作用，从而增强了边缘 SHG，并且可以通过将 WGM 模式与等离子体混合进一步增强。这些结果为构建用于高效非线性过程的特定结构提供了启示。
