论文标题
等离子Pancharatnam-Berry相元面的第二谐波成像与WS2的单层耦合
Second-harmonic imaging of plasmonic Pancharatnam-Berry phase metasurfaces coupled to monolayers of WS2
论文作者
论文摘要
频率转换的非线性过程（例如第二次谐波产生（SHG））通常遵守某些选择规则，这是由于保留了不同种类的物理量，例如角动量。对于由WS2（WS2）过渡金属二盐元素（TMDC）的单层创建的SHG，山谷 - 外部锁定选择规则可以预测交叉极化状态下的SHG信号。通过将等离激子纳米结构与TMDC的单层结合，实现了混合跨表面，这会影响由于附加的极化转换过程而影响这种非线性过程。在这里，我们观察到等离子跨表面会修饰与TMDC的光 - 物质相互作用，从而导致SHG信号相对于入射场是共偏其的，而TMDC的单层通常被禁止。我们通过将等离激元纳米棒放置在单层WS2的顶部，并研究山谷 - exciton从该系统中锁定SHG发射的不同参数（例如波长和极化）来制造这种杂种元面积。此外，我们通过使用Pancharatnam-Berry相效应向SHG信号中添加其他相位信息来展示混合跨表面对定制非线性过程的潜力。这允许将SHG发射到远场直接裁缝。
The nonlinear processes of frequency conversion like second harmonic generation (SHG) usually obey certain selection rules, resulting from the preservation of different kind of physical quantities, e.g., the angular momentum. For SHG created by monolayer of transition-metal dichalcogenides (TMDCs) like WS2, the valley-exciton locked selection rule predicts an SHG signal in the cross-polarization state. By combining plasmonic nanostructures with a monolayer of TMDC, a hybrid metasurface is realized which affects this nonlinear process due to an additional polarization conversion process. Here, we observe that the plasmonic metasurface modifies the light-matter interaction with the TMDC resulting in an SHG signal that is co-polarized with respect to the incident field, which is usually forbidden for solely monolayers of TMDC. We fabricate such hybrid metasurfaces by placing plasmonic nanorods on top of a monolayer WS2 and study the valley-exciton locked SHG emission from such system for different parameters, such as wavelength and polarization. Furthermore, we show the potential of the hybrid metasurface for tailoring nonlinear processes by adding additional phase information to the SHG signal using the Pancharatnam-Berry phase effect. This allows direct tailoring of the SHG emission to the far-field.
