光子学中的合成维度是近年来微纳光学和拓扑光子学的研究热点。通常意义上,一个光学系统的物理维度受限于其空间几何维度,因此极大地制约了光学系统所支持研究的物理现象。而研究者通过引入合成维度,可以突破几何维度对物理系统维度的制约,研究高维空间的物理问题。同时,合成维度的高度可控性和选择的丰富多样性,为简化系统设计、观察高维物理现象提供了很大的便利。本文介绍了光子学中合成维度的基本概念,回顾了近年来实现合成维度的各种设计方案,并初步探讨了其在基础物理研究和应用上的未来前景。

Synthetic dimension emerges as a new frontier of the researches in nanophotonics and topological photonics. It is general believed that the dimension of a physical system cannot be larger than its geometric dimensionality. With the introduction of additional synthetic dimensions, and combined with the intrinsic geometric dimension, one can investigate higher dimensional physics. Meanwhile, the synthetic dimension is highly controllable which contributes to the observation of many high-dimensional novel phenomena. In this review, we introduce the basic concepts of synthetic dimension in photonics, summarize various proposals and set-ups in generating new synthetic dimension, and briefly discuss potential contributions of synthetic dimension in fundamental physics as well as applications.