Revealing non-Hermitian band structure of photonic Floquet media

Jagang Park, Hyukjoon Cho, Seojoo Lee, Kyungmin Lee, Kanghee Lee, Hee Chul Park, Jung Wan Ryu, Namkyoo Park, Sanggeun Jeon, Bumki Min

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15 Citations (Scopus)


Periodically driven systems are ubiquitously found in both classical and quantum regimes. In the field of photonics, these Floquet systems have begun to provide insight into how time periodicity can extend the concept of spatially periodic photonic crystals and metamaterials to the time domain. However, despite the necessity arising from the presence of nonreciprocal coupling between states in a photonic Floquet medium, a unified non-Hermitian band structure description remains elusive. We experimentally reveal the unique Bloch-Floquet and non-Bloch band structures of a photonic Floquet medium emulated in the microwave regime with a one-dimensional array of time-periodically driven resonators. These non-Hermitian band structures are shown to be two measurable distinct subsets of complex eigenfrequency surfaces of the photonic Floquet medium defined in complex momentum space.

Original languageEnglish
Article numbereabo6220
JournalScience Advances
Issue number40
Publication statusPublished - 2022 Oct

Bibliographical note

Funding Information:
We thank S. Yu, X. Piao, and J. Choi for helpful discussions. Funding: This work was supported by the National Research Foundation of Korea (NRF) through the government of Korea (NRF-2017R1A2B3012364) (to J.P., H.C., S.L., Kyungmin Lee, Kanghee Lee, and B.M.), the Center for Advanced Meta-Materials (CAMM) funded by the Korean government (MSIP) as Global Frontier Project (NRF-2014M3A6B3063709) (to J.P., H.C., S.L., Ky.L., Ka.L., and B.M.), the National Research Foundation of Korea (NRF) through the government of Korea (NRF-2020R1C1C1012138) (to S.L.), and the Center for Theoretical Physics of Complex Systems (PCS) funded by the Korean government (MSIP) as IBS Project (IBS-R024-D1) (to J.-W.R. and H.C.P.). Author contributions: Conceptualization: B.M. Methodology: H.C., S.L., Ky.L., Ka.L., and S.J. Investigation: J.P. Visualization: J.P. and H.C. Supervision: B.M. Writing-original draft: J.P. and B.M. Writing-review and editing: All authors. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials.

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