Robust flat-top optical pulse shaping through a topological optical fiber

Subhranshu Rout, Bishnu P Pal and Somnath Ghosh
Department of Physics, École Centrale School of Engineering, Mahindra University, Hyderabad, Telangana, 500 043, India

In memory of Professor Gallieno Denardo, ICTP Italy

In this work, we propose a Su-Schrieffer-Heeger (SSH) model-based topological optical fiber, which consists of a topologically nontrivial photonic lattice around a topologically trivial photonic lattice, which are distinguished by the Zak phase, the relevant topological invariant for one-dimensional periodic systems. This configuration enables reliable edge-mode transmission at the interface of two lattices with different topological phases (trivial and/or nontrivial). We report that when a secant hyperbolic optical pulse is launched into the designed fiber through the robust topological edge mode, it gradually evolves into a flat-top optical pulse after propagating about 3 m in the designed fiber. This transition is caused by the unique dispersion features of the topological interface mode and its significant field confinement. In contrast to conventional flat-top pulse-generation techniques, which typically rely on complex Fourier synthesis using bulk optical components with stringent alignment requirements or on dispersion-engineered platforms such as tapered fibers, the proposed system offers a simple, stable, and robust alternative that leverages its inherent topological protection against random structural defects. The topological fiber–based approach presented here provides a compact and resilient platform for flat-top pulse shaping and highlights its potential for next-generation optical technologies. © Anita Publications. All rights reserved.
Doi: xxx
Keywords: Photonic crystal, SSH model, Edge mode, Flat-top pulse

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