单向波导及其在小型化非互易器件上的应用

One-way electromagnetic edge modes (OWEMs) and their related one-way waveguides are new concepts in the area of electromagnetic waves, which were proposed and demonstrated in recent years. These new concepts provide a novel and effective way to develop miniaturized nonreciprocal (optical) components. Materials with strong magneto-optical (MO) effect are the core constituents of a one-way waveguide system, where the time-reversal symmetry of MO materials is broken by applying an external dc magnetic field, and the propagation direction of OWEM is determined by the direction of the external magnetic field. In this project, we will explore the new characteristics of OWEMs based on several typical MO materials and develop their new applications. Since different types of MO materials generally correspond to different frequency ranges, our theoretical research will cover microwave, terahertz and infrared ranges. The research subjects of our particular interest include development of novel microwave one-way waveguides, realization of low-loss and broadband terahertz one-way waveguides, realization of infrared one-way waveguides, etc. The applications of one-way waveguides are also of our interest, where we will mainly focus on developing novel three-port circulators for all the three frequency ranges of interest, novel microwave beam splitters, microwave energy storages, etc. Among the abovementioned components, some are based on brand new concepts, and the others are based on new physical mechanisms and thus will provide remarkable improvement in performance. Based on our available experimental facilities, we will also conduct experimental research on many different aspects of OWEMs in microwave band. We think that this research project is not only valuable academically but also has promising application prospects.

单向电磁边界模式（OWEM）和相关单向波导，是电磁波领域近年来出现的全新概念，它们为实现小型化非互易（光学）功能器件提供了一条崭新、有效的途径。单向波导系统的核心成分是强磁光效应材料，其时间反演对称性的破缺通过外加恒定磁场来得到，OWEM传播方向由外磁场的方向决定。本项目将研究多种典型磁光材料下OWEM的新形态、新特性和新应用，实现中不同类型的磁光材料对应不同的频段，所以我们的理论研究涵盖微波、太赫兹和红外三个波段，研究重点有新型微波单向波导、低损耗/宽带太赫兹单向波导的实现，以及红外单向波导的实现等。本项目也致力于单向波导的应用研究，研究重点有新型三端口环形器（三个波段）、新型微波分束器，以及微波能量储存罐等，其中有全新概念的器件，其余则基于全新机理而性能优越。利用我们的实验条件，本项目将开展微波段相关丰富内容的实验研究。这些理论和实验研究，不仅具有学术价值还有重要的应用前景。

按项目预定的研究计划，我们对电磁波的单向传播及其应用开展了一系列的研究工作，取得了较为丰富的研究成果。在电磁波单向传播的基础物理方面，我们提出和研究了微波/太赫兹磁表面等离子体的强棒（robust）单向传播的物理模型和案例，研究了太赫兹半导体光子晶体的单向边缘模式，以及基于全反射机制的单向电磁模式等。在单向电磁模式的应用方面，我们研究和提出了微波/太赫兹波的有效捕获技术，微波/太赫兹高效率、可调分束器，谐振系统的时间-带宽极限的突破，新型微波全向漏波天线等。自项目启动以来，我们在Science，Optics Letters，Optics Express，以及Scientific Reports等期刊上发表了14篇论文（SCI收录）。有关电磁单向模式应用的研究工作—突破时间-带宽极限新型谐振系统的研究，成果于2017年7月发表在Science上（项目负责人为共同第一作者），国外网站对该成果发文，标题是“百年物理问题得到解决（A 100-year-old physics problem has been solved）”，国内环球科学、腾讯和浙江每日焦点等媒体也给以了正面的报道。