矢量光场相干度定义的统一表征及应用

The unique information carried by or induced by coherence, which is understood as the foundation for many applications in targets imaging and detecting, particle trapping, micro- and nano-photonics and so on, has become a frontier research of great concern at present. The theoretical difficulties currently encountered in the conduct of these applications are mainly concentrated in the degree of coherence has no uniform definition. There are still considerable controversy in the issues. And different definitions are available in the study of the coherence. The research in the essence of the definition of coherence can be regarded as the most essential point for the solution of the problems. This project intents to deeply study this point as follows: (1) From the representations of the complete coherence characteristic according to the available definitions of degree of coherence, the model which can explain the intrinsic link between the phase correlation and complete coherence will be structured, by studying the quantitative mathematical expression of the coherence which based on the statistical similarity in the scalar field, the intrinsic connection between the degree of coherence definitions will be uncovered, and then the unified representation of the definitions of degree of coherence in the vector field will be derived. (2) Furthermore, integrate with the expression of complete polarization properties, the representation of the degree of polarization will be obtained, and the analogy between the theory of coherence and the theory of polarization of light beams will be expounded. (3) The study on the characterization methods in the application of Cross-spectrally pure light will be carried on. The above investigations provide the theoretical basis for extend the work of purposefully modulating and manipulating the coherence from the nature attribute of coherence.

将相干参量携带或导致的独有特征信息用于目标成像与探测、粒子捕获、微纳光子学研究等应用是当前国际上极为关注的前沿研究。目前在开展这些应用时碰到的理论困难主要集中在矢量光场下相干度并没有统一的定义，存在着极大争议，研究中相干度定义的选择也无指导依据。其中，从本质上明确相干度定义的根本机理是解决问题的关键环节。本项目试图从统计相似特性入手进行深入探究: (1)从现存相干度定义下完全相干特性的表述出发，构造能说明完全相干与相位关联之间内在关系的模型，通过研究标量场中统计相似对相干度的定量数学表述，进而揭示现存相干度定义之间内在关联机制，最终实现对矢量场中相干度定义的统一表征；(2)进一步结合完全偏振特性的表述，实现对偏振度的表征，阐明相干偏振在本质层面上的相似属性；(3)研究该表征方法在交叉谱纯光上的应用。通过这三方面的研究，从相干本质属性层面为拓展对相干参量有目的性的调制和操控能力提供理论依据。

本课题按计划，着眼于矢量场相干和偏振特性携带的独有特征信息，研究了不同定义下的完全相干与完全偏振特性、交叉谱纯光特性、以及相干特性导致近场散射光谱演化规律，目的在于探索可控制的利用相干特性整体信息的方法以及实现矢量场相干度的表征，并阐述和解释时间域和频率域相干特性影响交叉谱纯光的主要因素，试图揭示一些未被充分认识的相干特性并为工程应用中主动的利用这些信息提供理论支持。一方面在光场本质属性研究方面，在研究交叉偏振度的演化机制的基础上，利用完全相干所对应光场分量间关系，对不同相干度定义下完全相干所隐含的偏振特性进行研究，揭示特定条件下光场相干、偏振以及交叉偏振特性的内在关联，并阐述不同相干度定义间关联；同时，有目的的以近场散射为载体，借助于不同散射粒子的位置偏离和边界条件变化，分析相干和偏振与散射隐失场光谱密度变化关联分布特征。另一方面，利用所建立的模型研究交叉谱纯光以及交叉谱纯场，得出了完全相干性与交叉谱纯光之间的关联以及准均匀光源辐射远场为交叉谱纯场的实现条件，进一步得出时间域频率域中的完全相干性关联特性。以上研究为光场探测、调控领域提供了理论依据。