Nontrivial coupling of light into a defect: the interplay of nonlinearity and topology

Shiqi Xia, Dario Jukić, Nan Wang, Daria Smirnova, Lev Smirnov, Liqin Tang, Daohong Song*, Alexander Szameit, Daniel Leykam, Jingjun Xu, Zhigang Chen*, Hrvoje Buljan*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    90 Citations (Scopus)


    The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures. However, when nonlinearity is introduced, many intriguing questions arise. For example, are there universal fingerprints of the underlying topology when modes are coupled by nonlinearity, and what can happen to topological invariants during nonlinear propagation? To explore these questions, we experimentally demonstrate nonlinearity-induced coupling of light into topologically protected edge states using a photonic platform and develop a general theoretical framework for interpreting the mode-coupling dynamics in nonlinear topological systems. Performed on laser-written photonic Su-Schrieffer-Heeger lattices, our experiments show the nonlinear coupling of light into a nontrivial edge or interface defect channel that is otherwise not permissible due to topological protection. Our theory explains all the observations well. Furthermore, we introduce the concepts of inherited and emergent nonlinear topological phenomena as well as a protocol capable of revealing the interplay of nonlinearity and topology. These concepts are applicable to other nonlinear topological systems, both in higher dimensions and beyond our photonic platform.

    Original languageEnglish
    Article number147
    JournalLight: Science and Applications
    Issue number1
    Publication statusPublished - 1 Dec 2020


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