基于倏逝波辐射的多维光场调控及应用研究

This project aims to study the hot topic in field of optics - multi-dimensional manipulation of optical field. It is proposed to take the evanescent wave of surface plasmon polariton, guide mode in dielectric waveguides and fibers as the excitation source, to be scattered, diffracted, or radiated by micro/nano structures with respect to its wavelength, phase, and polarization. It is expected to realize applications like generation of OAM, vector beam, holographic display, etc. Nowadays, the design of metasurface has advanced the research of optical field manipulation. However, it still suffers from several obstacles- bandwidth, loss, dynamic control, and integration level. Here, the proposed scheme is based on the conversion from evanescent wave to radiation wave, where the propagation process offers us one more dimension for manipulation. Although this two-steps process would possibly reduce the efficiency, it does provide a new avenue to overcome other blocks (especially for multiplexing and compact integration). Moreover, it is quite worth revealing the microscopic mechanism of the evanescent near-field wave interacting with the micro/nano structures. Based on the theoretical and experimental approaches, this project focuses on the fundamental physics with certain extents to possible applications. We expect in the exploration on new designs and we can work out applicable devices for the micro/nano photonics.

本项目针对当前光学领域的前沿课题“光场的多维调控”开展研究，提出将金属表面等离激元、介质波导模、光纤模式的表面倏逝场作为激发源，通过与人工设计的微纳结构的近场散射过程，综合调控结构的米散射、相干衍射和共振辐射，从波长、相位、偏振等多个自由度实现对空间光场进行调控，拟实现多维调控的空间角动量光束、矢量光场、全息成像等功能。当前，基于亚波长设计的超表面研究大大推动光场调控的发展。不过，它在带宽、损耗、动态调控及高集成度等方面还存在缺陷。本项目所提出的倏逝波与空间光转换过程中的光场调控思想，引入了倏逝波自身传播过程，为调控增加了新维度。这可能会一定程度上降低效率，但为克服其它瓶颈（特别是多维复用和高集成度）提供了新思路。另外，具有矢量特征的近场倏逝波与结构的散射机理还值得深入探讨。本项目理论与实验相结合，以基础研究为主向应用拓展，期望在发展新原理的同时开发出具有实际应用前景的微纳光子器件。

本项目针对基于波导中的导波/倏逝波与空间光场的辐射转换进行多维光场调控，在等离激元波导、介质波导、超构表面等系统进行波长、相位、偏振等多个自由度的调控。经过四年的努力，我们系统开展了等离激元辐射全息、介质波导的模式复用全息、超构表面消色差以及光谱变焦成像，以及空间光到导模转换、非线性转换等研究，阐明几类导波及其表面倏逝波与微纳结构相互作用及其散射、衍射的机理，发展出可集成波导模式的新型光场调控手段。主要成果总结如下：（1）提出基于表面等离激元传播复用的全息方法实现四重低串扰的等离激元散射全息成像，并进一步在金属/介质杂化波导中实现了基于模式复用导波全息；（2）开发了空间光场到等离激元/介质波导模式的转换设计，实现了轨道角动量光束的拓扑荷数检测以及基于铌酸锂波导的非线性倍频产生；（3）系统研究了超构表面多个相位机制的联合调控，实现了宽带消色差透镜、波长调控的光谱层析成像、以及高度集成的大视场显微成像；（4）揭示了波导阵列中特殊的耦合效应，用正负耦合等离激元波导阵列演示了无质量狄拉克粒子传输，拓扑波导阵列中零模耦合构建的稳健性耦合器，非厄米项实现了严格零模恢复等新颖效应。相关研究为开发多波长、高分辨、宽视场、大景深等特性成像功能，实现基于微纳结构设计的新型光子器件提供了指导。相关成果共发表论文22篇（包括Nature Nanotech. 2篇，Nature Commun. 1篇，Light Sci. Appl. 1篇，Nano Letters 1篇，Phys. Rev. Lett. 2篇，Laser Photon. Rev. 2篇等，及综述1篇）。项目承担人收到国际/国内会议及相关学术单位邀请做邀请报告或专题讲座/公开课四十余次。