超构表面对非线性谐波辐射中光的自旋与轨道角动量的调控

Spin and orbital angular momentum (SAM and OAM) of light have broad and important applications in the classic light, quantum optical communication, super-resolution imaging, and optical tweezers and so on. In the linear optics, the coupling mechanism between the spin and the angular momentum of the light is relatively mature. However, in the field of nonlinear optics, such as in harmonic generations, how to realize the multi-freedoms manipulation of the spin and orbital angular momentum of light is essential for high capacity optical information processing in future. Although SAM and OAM of light in nonlinear optical regime have been studied separately, however, the mechanism of their mutual coupling is still lack of systematic exploration. Recently, the PI of this proposal have found that there is a specific selection rule between the SAM of second and third harmonic generations (SHG and THG) and the rotational symmetry of a metasurface. For the first time, we also proposed and verified the existence of Berry geometric phase in the process of nonlinear harmonic generations on the metasurfaces. The project plans to introduce the topological charge into the metsurface by using meta-atoms with nonlinear geometric Berry phases to achieve simultaneous control of SAM and OAM of the light in both SHG and THG processes. Understanding the mechanism of manipulation of SAM and OAM of light in nonlinear harmonic generations will provide an important scientific and technical basis for designing multi - dimension optical information processing chips.

光的自旋、轨道角动量在经典光、量子光通信、超分辨成像、光镊等领域已有广泛且重要应用。在线性光学范畴，光的自旋与轨道角动量的耦合机理已经相对成熟。在非线性光学范畴，如谐波辐射过程中如何在微纳光学器件上实现对光的自旋与轨道角动量的多维度调控，对未来的高密度光信息处理至关重要。尽管在非线性领域大家对这两个角动量已分别有所研究，然而对于二者相互耦合的机理尚缺乏系统阐述。申请人近来在倍频、三倍频辐射过程中发现超构表面的旋转对称性与光的自旋角动量存在特定的选择定则。申请人等亦首次提出并验证了超构表面上非线性光学谐波辐射过程中贝里几何相位的存在。该项目计划通过具有非线性贝里几何相位的超构单元将拓扑电荷引入超构表面，从而实现对超构表面上倍频、三倍频辐射中光的自旋-轨道角动量的同时控制。理解超构表面上谐波辐射过程中光的自旋、轨道角动量的调控机理，可为设计多维度光信息处理芯片等提供重要科学与技术基础。

光的自旋、轨道角动量在经典光、量子光通信、超分辨成像、光镊等领域已有广泛且重要应用。在线性光学范畴，光的自旋与轨道角动量的耦合机理已经相对成熟。在非线性光学范畴，如谐波辐射过程中如何在微纳光学器件上实现对光的自旋与轨道角动量的多维度调控，对未来的高密度光信息处理至关重要。尽管在非线性领域大家对这两个角动量已分别有所研究，然而对于二者相互耦合的机理尚缺乏系统阐述。申请人此前在倍频、三倍频辐射过程中发现超构表面的旋转对称性与光的自旋角动量存在特定的选择定则；提出并验证了超构表面上非线性光学谐波辐射过程中贝里几何相位的存在。该项目计划通过具有非线性贝里几何相位的超构单元将拓扑电荷引入超构表面，从而实现对超构表面上倍频、三倍频辐射中光的自旋-轨道角动量的同时控制。理解超构表面上谐波辐射过程中光的自旋、轨道角动量的调控机理，为设计多维度光信息处理芯片等提供重要科学与技术基础。.首次报道了非线性光学晶体中倍频光的自旋-轨道角动量级联效应[Nature Photonics 14, 658-662 (2020)]。鉴于光的自旋-轨道相互作用以及级联效应在传统晶体和光学超构材料中的普适性，人们可以设计用于产生光的自旋-轨道角动量的各种非线性光学人工结构材料。总体来看，从自旋-轨道相互作用这个角度重新回顾晶体中的非线性光学过程仍然极为重要，相关研究结果也有望在量子信息处理、单模涡旋光源、光磁化等领域具有广泛的应用前景。本项目按预期顺利完成了申请书中制定的各项研究计划。在项目资助下，发表SCI论文37篇，包括Nature Photonics 1篇，Nature Communications 1篇，Science Advances 1篇，Advanced Materials 1篇，Nano Letters 5篇。申请国家发明专利6项，其中3项获授权。培养博士后2名，培养和招收在读博士生7名，培养硕士生3名。申请人参与国内外学术会议并做邀请报告13次。申请人获得2019年度求是杰出青年学者奖。