无序辅助实动量拓扑光子晶体

momo

https://doi.org/10.1038/s41586-025-08632-9

拓扑光子学通过设计人工光学材料（如光子晶体、超表面等）实现了对光场拓扑特性的操控，催生了光涡旋生成、拓扑激光等创新应用。传统观点认为，无序（如结构缺陷或随机扰动）会破坏拓扑保护的鲁棒性，因此需极力避免。然而，本文提出了一种颠覆性思路：通过主动引入实空间的无序，生成Pancharatnam-Berry（PB）相位，从而在保持动量空间拓扑奇点的同时，赋予光子晶体额外的信息编码能力。这种“实空间-动量空间双拓扑”设计不仅突破了传统拓扑光子学的局限，还为实现多功能集成光学器件开辟了新途径。

The document discusses a novel approach to topological photonic crystals that utilizes disorder to enhance optical functionalities.
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Disorder-assisted real–momentum topological photonic crystal
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• The study proposes using real-space disorder in topological photonic crystals to generate Pancharatnam–Berry phase.
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• This method allows for the simultaneous generation of real-space broadband vortex images and resonant momentum-space vortex beams.
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• The approach preserves the topology of bound states in continuum while enhancing optical device capabilities.
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Topological photonics and bound states in continuum
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• Topological photonics utilizes artificial optical materials for manipulating light with non-trivial topological properties.
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• Bound states in continuum (BICs) are non-radiative resonances that exhibit singularities in momentum space.
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• Recent advancements include folded photonic crystals enabling spin-valley-locked emission.
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Real–momentum duality
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• The research demonstrates real–momentum duality by patterning topological phase winding in real space.
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• This results in the generation of dual vortices with higher-dimensional topological charges.
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• The study highlights the ability to encode holographic images through the rotation of meta-atoms.
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Robustness of momentum topology
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• Simulations confirm that the topological eigenmode profiles remain unaffected by structural variations in nanorod geometries.
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• The study shows that momentum-space singularities persist even with significant disorder introduced by notch perturbations.
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• The Q factor of the system indicates high resonance stability despite geometric imperfections.
  

Amplitude-modulated Pancharatnam–Berry phase
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• The research explores the manipulation of transmission amplitude and PB phase through varying rotation angles and notch depths.
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• A full 2π range of PB phase is achieved, enabling the encoding of arbitrary holographic images.
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• The amplitude-modulated PB phase allows for the generation of complex vortex patterns.
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Experimental realization
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• The fabricated photonic crystal demonstrates the capability to generate real-space vortices and momentum-space vortices simultaneously.
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• Experimental results confirm the robustness of the real–momentum topology duality against structural imperfections.
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• The study showcases the potential for enhanced data capacity and applications in optical encryption and holography.
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Conclusion and outlook
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• The findings integrate topology with engineered disorder, pushing the boundaries of flat optics.
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• Future research may explore higher-order momentum-space charges and temporal topology interactions.
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• The approach holds promise for applications in optical trapping, augmented reality, and advanced meta-vehicles.
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