近日，清华大学深圳国际研究生院宋清华团队研究了无序辅助实动量拓扑光子晶体。相关论文于2025年2月26日发表在《自然》杂志上。

拓扑缺陷和无序相互抵消。直观地说，无序被认为是有害的，需要努力减轻其在传统拓扑光子学中的影响。

研究组提出了一种反直觉的方法，利用实动量拓扑光子晶体，利用实空间无序产生潘查拉特纳姆-贝里相位，而不会破坏源自连续体中束缚态的动量空间奇异性。这种方法允许平面光学器件在真实空间中编码空间信息甚至额外的拓扑电荷，同时保持动量空间中连续体中束缚态的拓扑结构，并具有固有的对齐性。

作为概念验证，研究组展示了在窄带宽的共振动量空间涡旋光束旁边同时独立生成真实空间宽带涡旋或全息图像，这是传统方法无法实现的。这种工程无序有助于获得巨大的内在自由度，而不会增加额外的尺寸或损害光学平坦度。这项对实动量对偶的发现不仅为拓扑光子学中的无序工程奠定了基础，还为光学波前整形、加密和通信开辟了新的途径。

附：英文原文

Title: Disorder-assisted real–momentum topological photonic crystal

Author: Qin, Haoye, Su, Zengping, Zhang, Zhe, Lv, Wenjing, Yang, Zijin, Chen, Weijin, Gao, Xinyue, Wei, Heng, Shi, Yuzhi, Li, Bo, Zhou, Ji, Fleury, Romain, Qiu, Cheng-Wei, Song, Qinghua

Issue&Volume: 2025-02-26

Abstract: Topological defects and disorder counteract each other1,2,3,4,5. Intuitively, disorder is considered detrimental, requiring efforts to mitigate its effects in conventional topological photonics6,7,8,9. We propose a counter-intuitive approach that exploits a real–momentum topological photonic crystal that harnesses real-space disorder to generate a Pancharatnam–Berry phase10,11, without disrupting the momentum-space singularity originating from bound states in the continuum12. This methodology allows flat optical devices to encode spatial information or even extra topological charge in real space while preserving the topology of bound states in the continuum in momentum space with inherent alignment. Here, as a proof of concept, we demonstrate the simultaneous and independent generation of a real-space broadband vortex or a holographic image alongside resonant momentum-space vortex beams with a narrow bandwidth, which cannot be achieved with conventional methods. Such engineered disorder contributes to vast intrinsic freedoms without adding extra dimensions or compromising the optical flatness13,14. Our findings of real–momentum duality not only lay the foundation for disorder engineering in topological photonics but also open new avenues for optical wavefront shaping, encryption and communications.

DOI: 10.1038/s41586-025-08632-9

Source: https://www.nature.com/articles/s41586-025-08632-9