利用液晶的自组装和刺激响应特性，实现近晶相液晶多层级超结构的灵活构筑、动态操控和多功能应用对于激发更多前沿的创新性功能器件并推动液晶超结构的实用化进程具有重要意义。本文从近晶相液晶超结构的生长制备、多元外界刺激对缺陷结构的调制方法和动态调控规律等方面进行系统研究。首先，探究了图案化取向场和旋涂条件对近晶相液晶拓扑超结构的形态与大小的操控；然后，验证了焦锥畴超结构的微透镜成像功能，并通过材料复合优化和引入聚合物稳定策略，实现了正方焦锥畴阵列在35 ℃下（向列相）的电刺激动态调控性能；最后，研究了手性、光场和热场对双相态液晶超结构带来的多维度调控。本研究充分利用光取向场、聚合物网络、电场、手性、光场等多元外场刺激，实现了对近晶相液晶多层级超结构的多维度调控。

We review the physics and some applications of photonic structures designed for the realization of strong nonlinear chiroptical response. We pay much attention to the recent strategy of utilizing different types of optical resonances in metallic and dielectric subwavelength structures and metasurfaces, including surface plasmon resonances, Mie resonances, lattice-guided modes, and bound states in the continuum. We summarize earlier results and discuss more recent developments for achieving large circular dichroism combined with the high efficiency of nonlinear harmonic generation.

为了分析球形颗粒的手性信号增强机理，基于T矩阵法对手性球形颗粒的Mie散射特性进行了研究，分析了基于入射光束轨道角动量（OAM）的调控和颗粒特性参数调控的手性信号增强机理。对紧聚焦线偏振光的波前进行调控，通过调控光束携带OAM的符号实现OAM二色性的测量，并研究OAM阶数与手性信号强度之间的关系。当光束携带OAM的阶数与小球的尺寸相匹配时得到较圆偏振光散射圆二色性信号22.8倍的提升。同时分析了小球特性参数（颗粒尺寸、手性参数）对OAM二色性信号的影响。

We propose a framework that connects the spatial symmetries of a metasurface to its material parameter tensors and its scattering matrix. This provides a simple and universal way to effortlessly determine the properties of a metasurface scattering response, such as chirality or asymmetric transmission, and which of its effective material parameters should be taken into account in the prospect of a homogenization procedure. In contrast to existing techniques, this approach does not require any a priori knowledge of group theory or complicated numerical simulation schemes, hence making it fast, easy to use and accessible. Its working principle consists in recursively solving symmetry-invariance conditions that apply to dipolar and quadrupolar material parameters, which include nonlocal interactions, as well as the metasurface scattering matrix. The overall process thus only requires listing the spatial symmetries of the metasurface. Using the proposed framework, we demonstrate the existence of multipolar extrinsic chirality, which is a form of chiral response that is achieved in geometrically achiral structures sensitive to field gradients, even at normal incidence.

本文提出了一种基于相变材料Ge₂Sb₂Te₅ (GST)的圆二色性可调谐外在手征超表面，该超表面由两层对称的银(Ag)方形开口谐振环和GST中间层单元周期排列而成。结合斜入射光线，该超表面能实现与手征结构相同的电磁特性。数值模拟结果表明：该超表面在50 THz~300 THz的频率范围内，GST为非晶态时，圆二色性(CD)值最大为0.85；GST为晶态时，CD值最大为0.52。当GST在两种相态(非晶态-晶态)之间切换时，实现了70 THz左右的频率调谐。通过研究电场分布，解释了圆二色性产生的原因；还研究了入射角和结构参数对该超表面圆二色性的影响。这项研究在光频段高效偏振调制器件、圆偏振器和偏振滤光器等方面有潜在的应用价值。

Controlling energy flow in waveguides has attractive potential in integrated devices from radio frequencies to optical bands. Due to the spin-orbit coupling, the mirror symmetry will be broken, and the handedness of the near-field source will determine the direction of energy transport. Compared with well-established theories about spin-momentum locking, experimental visualization of unidirectional coupling is usually challenging due to the lack of generic chiral sources and the strict environmental requirement. In this work, we design a broadband near-field chiral source in the microwave band and discuss experimental details to visualize spin-momentum locking in three different metamaterial waveguides, including spoof surface plasmon polaritons, line waves, and valley topological insulators. The similarity of these edge waves relies on the abrupt sign change of intrinsic characteristics of two media across the interface. In addition to the development of experimental technology, the advantages and research status of interface waveguides are summarized, and perspectives on future research are presented to explore an avenue for designing controllable spin-sorting devices in the microwave band.

作为生物体的本质属性，物质的手性表征在生理学和药理学领域有着重要的意义。当电磁波与手性材料作用时，会出现旋光效应、圆二色性和手性光力等特殊的光学活性现象，并成为材料手性检测的强大工具。由于手性分子的结构远小于激发光的波长，因此分子自身的手性光学效应通常很弱，极大限制了检测技术的精度。近年来，纳米光子技术的进步有望增强纳米尺度下光与物质之间原本很弱的手性光学效应，使得手性的高灵敏度、高分辨率检测成为可能。回顾了手性光学的发展及其在生物分子检测等方面的应用，讨论了基于等离子耦合圆二色性和超手性近场在圆二色性增强方面的策略，介绍了基于横向手性光力的物质构型分选和基于结构光场光力效应的手性结构表征方法，并对该领域未来进一步的发展进行了展望。