Floquet parity-time symmetry in integrated photonics

Weijie Liu, Quancheng Liu, Xiang Ni, Yuechen Jia, Klaus Ziegler, Andrea Alù, Feng Chen

Research output: Contribution to journalArticlepeer-review


Parity-time (PT) symmetry has been unveiling new photonic regimes in non-Hermitian systems, with opportunities for lasing, sensing and enhanced light-matter interactions. The most exotic responses emerge at the exceptional point (EP) and in the broken PT-symmetry phase, yet in conventional PT-symmetric systems these regimes require large levels of gain and loss, posing remarkable challenges in practical settings. Floquet PT-symmetry, which may be realized by periodically flipping the effective gain/loss distribution in time, can relax these requirements and tailor the EP and PT-symmetry phases through the modulation period. Here, we explore Floquet PT-symmetry in an integrated photonic waveguide platform, in which the role of time is replaced by the propagation direction. We experimentally demonstrate spontaneous PT-symmetry breaking at small gain/loss levels and efficient control of amplification and suppression through the excitation ports. Our work introduces the advantages of Floquet PT-symmetry in a practical integrated photonic setting, enabling a powerful platform to observe PT-symmetric phenomena and leverage their extreme features, with applications in nanophotonics, coherent control of nanoscale light amplification and routing.

Original languageEnglish
Article number946
JournalNature Communications
Issue number1
StatePublished - 31 Jan 2024

Bibliographical note

Publisher Copyright:
© 2024, The Author(s).


This work was supported by the National Natural Science Foundation of China (Grant No. 12174222), Natural Science Foundation of Shandong Province (Grant No. ZR2021ZD02), and Taishan Scholars Project of Shandong Province (tspd20210303). Q.L. acknowledges support from the Israel Science Foundation (Grant No. 1614/21). K.Z. acknowledges support from the Julian Schwinger Foundation for Physics Research. X.N. and A.A. were supported by the Simons Foundation and the Air Force Office of Scientific Research MURI program. X.N. acknowledges support from Research Startup Funds of Central South University (Grant No. 11400-506030109).

FundersFunder number
Air Force Office of Scientific Research
Simons Foundation
Julian Schwinger Foundation for Physics Research
National Natural Science Foundation of China12174222
Central South University11400-506030109
Israel Science Foundation1614/21
Natural Science Foundation of Shandong ProvinceZR2021ZD02
Taishan Scholar Project of Shandong Provincetspd20210303


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