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arXiv · 1606.05851

Anomalous Light Scattering by Topological ${\mathcal{PT}}$-symmetric Particle Arrays

C. W. Ling·Ka Hei Choi·T. C. Mok·Z. Q. Zhang·Kin Hung Fung
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Abstract

Robust topological edge modes may evolve into complex-frequency modes when a physical system becomes non-Hermitian. We show that, while having negligible forward optical extinction cross section, a conjugate pair of such complex topological edge modes in a non-Hermitian $\mathcal{PT}$-symmetric system can give rise to an anomalous sideway scattering when they are simultaneously excited by a plane wave. We propose a realization of such scattering state in a linear array of subwavelength resonators coated with gain media. The prediction is based on an analytical two-band model and verified by rigorous numerical simulation using multiple-multipole scattering theory. The result suggests an extreme situation where leakage of classical information is unnoticeable to the transmitter and the receiver when such a $\mathcal{PT}$-symmetric unit is inserted into the communication channel.

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C. W. Ling, Ka Hei Choi, T. C. Mok, Z. Q. Zhang, Kin Hung Fung. 2016-08-04. Anomalous Light Scattering by Topological ${\mathcal{PT}}$-symmetric Particle Arrays. https://doi.org/10.1038/srep38049

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