ABSTRACT Topological photonics has emerged as a route to robust optical circuitry protected against disorder1,2 and now includes demonstrations such as topologically protected lasing3,4,5

and single-photon transport6. Recently, nonlinear optical topological structures have attracted special theoretical interest7,8,9,10,11, as they enable tuning of topological properties by a

change in the light intensity7,12 and can break optical reciprocity13,14,15 to realize full topological protection. However, so far, non-reciprocal topological states have only been realized

using magneto-optical materials and macroscopic set-ups with external magnets4,16, which is not feasible for nanoscale integration. Here we report the observation of a third-harmonic signal

robust against various perturbations and structural defects. Moreover, we show that the interplay between topology, bi-anisotropy and nonlinearity makes parametric photon generation tunable

and non-reciprocal. Our study brings nonlinear topological photonics concepts to the realm of nanoscience. Access through your institution Buy or subscribe This is a preview of subscription

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* Learn about institutional subscriptions * Read our FAQs * Contact customer support SIMILAR CONTENT BEING VIEWED BY OTHERS NON-HERMITIAN TOPOLOGICAL PHASE TRANSITIONS CONTROLLED BY

NONLINEARITY Article 23 October 2023 ADIABATIC TOPOLOGICAL PHOTONIC INTERFACES Article Open access 02 August 2023 MAGNETICALLY CONTROLLABLE MULTIMODE INTERFERENCE IN TOPOLOGICAL PHOTONIC

CRYSTALS Article Open access 14 May 2024 DATA AVAILABILITY The data that support the plots within this paper and other findings of this study are available from the corresponding author upon

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metasurfaces. _Nano Lett._ 18, 3978–3984 (2018). Download references ACKNOWLEDGEMENTS The authors acknowledge financial support from the Australian Research Council and the Strategic Fund of

the Australian National University. A part of this research was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. Numerical

calculations were supported in part by the Ministry of Education and Science of the Russian Federation (Zadanie no. 3.2465.2017/4.6) and the Russian Foundation for Basic Research (grant no.

18-02-00381). A.P. and A.Sl. acknowledge partial support from the Russian Foundation for Basic Research (grant no. 18-32-20065). Y.K. thanks H. Atwater, B. Kanté, D. Leykam and E. Poutrina

for discussions. AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Nonlinear Physics Centre, Australian National University, Canberra, Australian Capital Territory, Australia Sergey Kruk, 

Alexander Poddubny, Daria Smirnova, Lei Wang & Yuri Kivshar * ITMO University, St Petersburg, Russia Alexander Poddubny, Alexey Slobozhanyuk & Yuri Kivshar * Ioffe Institute, St

Petersburg, Russia Alexander Poddubny * Institute of Applied Physics, Russian Academy of Science, Nizhny Novgorod, Russia Daria Smirnova * Lomonosov Moscow State University, Moscow, Russia

Alexander Shorokhov * Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA Ivan Kravchenko * Laser Physics Centre, Australian National University,

Canberra, Australian Capital Territory, Australia Barry Luther-Davies Authors * Sergey Kruk View author publications You can also search for this author inPubMed Google Scholar * Alexander

Poddubny View author publications You can also search for this author inPubMed Google Scholar * Daria Smirnova View author publications You can also search for this author inPubMed Google

Scholar * Lei Wang View author publications You can also search for this author inPubMed Google Scholar * Alexey Slobozhanyuk View author publications You can also search for this author

inPubMed Google Scholar * Alexander Shorokhov View author publications You can also search for this author inPubMed Google Scholar * Ivan Kravchenko View author publications You can also

search for this author inPubMed Google Scholar * Barry Luther-Davies View author publications You can also search for this author inPubMed Google Scholar * Yuri Kivshar View author

publications You can also search for this author inPubMed Google Scholar CONTRIBUTIONS S.K., A.Sl. and Y.K. conceived the idea. S.K., A.Sh. and B.L.-D. performed the experimental

measurements. A.P. and D.S. developed the discrete dipole theoretical model. D.S., L.W. and A.Sl. performed numerical calculations. I.K. and S.K. fabricated the samples. Y.K. supervised the

project. All authors contributed to the discussion of results and manuscript preparation. CORRESPONDING AUTHOR Correspondence to Yuri Kivshar. ETHICS DECLARATIONS COMPETING INTERESTS The

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THIS ARTICLE Kruk, S., Poddubny, A., Smirnova, D. _et al._ Nonlinear light generation in topological nanostructures. _Nature Nanotech_ 14, 126–130 (2019).

https://doi.org/10.1038/s41565-018-0324-7 Download citation * Received: 10 April 2018 * Accepted: 10 November 2018 * Published: 17 December 2018 * Issue Date: February 2019 * DOI:

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