空域分形光场的调控、新效应及其潜在应用

In the NSFC key program finished and the 973 program to be finished, the study on vector optical fields focuses on: principles of manipulating polarization, spatiotemporal evolution, and novel effects and potential applications of linear and nonlinear interaction with the matter. We have resolved the issues on the principles and experimental realization of the local linearly-polarized vector fields with arbitrarily spatial distribution and arbitrarily orientated polarization, and of some hybridly polarized vector fields with specially spatial distributions. However, we cannot still resolve the issue on principles and experimental realization of vector fields with arbitrarily spatial distribution and arbitrary polarization states (including linear polarization with arbitrary orientation, elliptic polarization with arbitrary orientation, ellipticity and sense, and circular polarization with arbitrary sense). In fact, such a unresolved issue as mentioned above is one of the key issues focused in this project. After the above issue has been resolved, the second of issues focused in this project is, through introducing the concept of fractal and based on the self-similarity and iteration rules, to realize the design and control of spatial fractal structures and the generation of spatial fractal vector fields. Furthermore, we will study the unique novel linear and nonlinear effects, peculiar properties and potential applications, which are originated from the fractal structure. We will also reveal the regularities and mechanisms of influences of structure, dimension and level of the spatial fractals. We will explore the principles, schemes and approaches of feasibilities realizing the far-field focusing beyond the diffraction and the far-field imaging beyond the resolution by using the spatial fractal structure.

在已结题基金委重点项目和即将结题的重大研究计划项目，对矢量光场，重点研究：偏振调控原理和构建、时空演化规律和新颖特性，与物质的线性和非线性相互作用、新颖效应及其潜在应用。解决了任意空间分布、任意取向的局域线偏振矢量光场和一些具有特定空间分布的杂化偏振矢量光场的生成原理和实验实现问题。然而，任意空间分布、任意偏振态(任意取向线偏振，任意取向、椭偏度和手性的椭圆偏振，任意手性圆偏振)的矢量光场的生成原理和实验实现仍未被解决。这正是本项目所要解决的关键问题之一。其二，在解决上述关键问题的基础上；引入分形概念，基于自相似原则和迭代原则，实现空域分形结构的设计和控制以及空域分形矢量光场的生成。进而，研究空域分形结构所特有的新颖线性和非线性效应以及新奇特性和应用。揭示空域分形的结构、维数和层次的影响规律和机理。探寻空域分形结构在轨道角动量、远场超衍射聚焦和远场超分辨成像应用的可行性的原理、方案和途径。

分形是自然界中普遍存在的现象，是一种具有自相似特性的图像、现象或者物理过程。分形具有自相似性和标度不变性，由于其特有的新颖特性目前已发展成为一门新学科，并不断应用于自然科学的各个领域。.本项目首次把分形与矢量光场联系起来，提出了一种新型的空间结构光场：分形矢量光场，基于自相似原则和迭代原则，实现空域分形结构的设计和调控原理；提出了各种分形矢量光场的生成方案和原理，研究了其演化规律及其他物理新特性；提出了多重分形矢量光场的概念及生成技术，研究了分形结构的维数和层次，对其空域演化、焦场等的影响及新颖效应，发现其良好的信息恢复能力；基于分形矢量光场构造了偏振奇点光场，进一步研究其新颖传输特性，发现了其赝拓扑特性及奇点的劈裂和拓扑荷守恒等新现象。研究了空域矢量光场与非线性晶体的相互作用特点及机理，并探究了基于空域矢量光场调控的稳定飞秒成丝。此外，通过采用新器件和新的光场调控生成技术，一方面实现了对光场的偏振、振幅和相位的独立和联合调控，从而获得任意控制的偏振分布，另一方面还解决了目前光场生成效率低的问题，目前任意光场生成效率可达45%以上，这将极大的拓展其应用范围。.总之，本项目以空域分形光场(尤其偏振空域分形的矢量光场)的调控为中心，系统完成了空域分形矢量光场的理论描述、实验生成和各种类型光场设计的工作，深入研究了空域调控分形光场的调控原理与技术、传输演化、新颖特性及其在光学加密、光学微操纵以及与物质(微结构)的线性和非线性相互作用等方面的潜在应用。.基于该项目的研究，进一步提升了课题组在光场调控领域的研究水平及国内外的学术地位，拓宽了相关领域的视野，解决了若干关键的科研难题，发表了一批高水平的论文，取得了一系列具有影响力的研究成果。更为关键的是，在研究的过程中，课题组注重青年优秀人才的挖掘和培养，目前已有10多名毕业生加入到国内的其他研究课题组并为他们的研究贡献才情和智慧。