Topological band structure via twisted photons in a degenerate cavity

• Published in: Nature communications Vol. 13; no. 1; pp. 2040 - 7
• Main Authors: Yang, Mu, Zhang, Hao-Qing, Liao, Yu-Wei, Liu, Zheng-Hao, Zhou, Zheng-Wei, Zhou, Xing-Xiang, Xu, Jin-Shi, Han, Yong-Jian, Li, Chuan-Feng, Guo, Guang-Can
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.04.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/400/385; 639/766/483/3926; Angular momentum; Coils (windings); Coupling; Degrees of freedom; Design; Energy bands; Frequency dependence; Humanities and Social Sciences; Lattices; multidisciplinary; Optical components; Photons; Physics; Science; Science (multidisciplinary); Topology
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-29779-3

Synthetic dimensions based on particles’ internal degrees of freedom, such as frequency, spatial modes and arrival time, have attracted significant attention. They offer ideal large-scale lattices to simulate nontrivial topological phenomena. Exploring more synthetic dimensions is one of the paths toward higher dimensional physics. In this work, we design and experimentally control the coupling among synthetic dimensions consisting of the intrinsic photonic orbital angular momentum and spin angular momentum degrees of freedom in a degenerate optical resonant cavity, which generates a periodically driven spin-orbital coupling system. We directly characterize the system’s properties, including the density of states, energy band structures and topological windings, through the transmission intensity measurements. Our work demonstrates a mechanism for exploring the spatial modes of twisted photons as the synthetic dimension, which paves the way to design rich topological physics in a highly compact platform. Tailoring topological physics in optical cavity is a challenge that would allow new possibilities for the design optical components. In this paper, the authors, harnessing the potential of synthetic dimensions, experimentally demonstrate a degenerate cavity containing many optical angular momenta.