Publications by Zhechen Zhang | EPFL Graph Search

Topological photonic transport in disordered scattering networks

This Ph.D. thesis unveils the unique topological phenomena occurring in such networks, focusing on the intricate interplay between their Floquet topology, the presence of disorder, and their unitary scattering at microscopic and macroscopic scales. Using t ...

EPFL2024

Anomalous and Chern topological waves in hyperbolic networks

Romain Christophe Rémy Fleury, Aleksi Antoine Bossart, Haoye Qin, Zhechen Zhang

Hyperbolic lattices are a new type of synthetic materials based on regular tessellations in non-Euclidean spaces with constant negative curvature. While so far, there has been several theoretical investigations of hyperbolic topological media, experimental ...

Nature Research2024

Disclination states in nonreciprocal topological networks

Romain Christophe Rémy Fleury, Haoye Qin, Qiaolu Chen, Zhechen Zhang

Recently, nonreciprocal two-dimensional unitary scattering networks have gained considerable interest due to the possibility of obtaining robust edge wave propagation in their anomalous topological insulating phase. However, zero-dimensional states in such ...

2024

Anomalous‐Chern Steering of Topological Nonreciprocal Guided Waves

Romain Christophe Rémy Fleury, Haoye Qin, Qiaolu Chen, Zhechen Zhang

Nonreciprocal topological edge states based on external magnetic bias have been regarded as the last resort for genuine unidirectional wave transport, showing superior robustness over topological states with preserved time-reversal symmetry. However, fast ...

Wiley2024

Skyrmion Quasi‐Bound States in the Continuum for 3D Light Trapping in Arbitrarily Large Volumes

Romain Christophe Rémy Fleury, Haoye Qin, Qiaolu Chen, Zhechen Zhang

Real‐world resonances face surface‐scaling radiation leakage, hindering light confinement in optically large systems. Conventional bound states in continuum (BICs) challenge this by enabling states with theoretically infinite lifetimes in 2D periodic struc ...

Wiley2024

Anomalous topological waves in strongly amorphous scattering networks

Romain Christophe Rémy Fleury, Pierre Delplace, Zhechen Zhang

Topological insulators are crystalline materials that have revolutionized our ability to control wave transport. They provide us with unidirectional channels that are immune to obstacles, defects, or local disorder and can even survive some random deformat ...

2023

Superior robustness of anomalous non-reciprocal topological edge states

Romain Christophe Rémy Fleury, Pierre Delplace, Zhechen Zhang

Robustness against disorder and defects is a pivotal advantage of topological systems, manifested by the absence of electronic backscattering in the quantum-Hall and spin-Hall effects, and by unidirectional waveguiding in their classical analogues. Two-dim ...

2021

Fiber-interface directional coupler inscribed by femtosecond laser for refractive index measurements

Jiangtao Zhou, Jiachen Wang, Zhechen Zhang, Yiping Wang

A novel fiber-interface directional waveguide coupler was inscribed on the surface of a coreless fiber by femtosecond laser, and was successfully applied to highly sensitive refractive index (RI) measurements. The primary arm was first inscribed to couple ...

2020