Researchers Design Topological Fiber Laser Robust Against Manufacturing Defects
Physicists have modeled a topological fibre laser based on a non-Hermitian Su-Schrieffer-Heeger chain embedded in a photonic crystal fibre, demonstrating robustness against fabrication disorder. The design exploits a winding-number topological invariant and broken PT symmetry to selectively amplify a boundary lasing mode, even in the presence of nonlinear saturable gain. This work could improve the stability of multi-core fibre lasers used to generate reliable quantum and classical optical signals.
A new preprint from arXiv presents a theoretical design and numerical model for a topological fibre laser that maintains stable lasing modes despite disorder introduced during manufacturing. The system embeds a non-Hermitian Su-Schrieffer-Heeger (SSH) chain within a photonic crystal fibre, using a winding-number invariant and a PT-symmetric bulk configuration with explicitly broken PT symmetry at the interface to achieve topological protection. Mode-coupling theory and finite-element simulations show that adding gain at the topological interface selectively amplifies the boundary mode over bulk modes. Crucially, the robustness persists even when nonlinearity is introduced through saturable gain, which is a realistic feature of actual laser operation. The proposed fabrication route relies on established stack-and-draw techniques with doped cores, making experimental realization feasible with current technology. Prior work had demonstrated topological robustness in passive (gain-free) fibres, but this study is the first to extend the concept to an active lasing system. The authors argue the approach offers a general framework for topological protection in non-Hermitian photonic devices.
What's missing
The study is a theoretical and simulation-based preprint and has not yet undergone peer review. Key open questions include whether fabricated prototypes will match the modeled performance, how the design scales to higher core counts, and what the practical lasing thresholds and output power levels would be in an experimental device. The degree of disorder tolerance quantified in simulations may not fully capture all real-world fabrication imperfections.
What different sources said
- arXiv physicsCenter
Robustness against disorder in topological fibre lasers with explicitly broken PT symmetry
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