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Media type:
E-Article
Title:
Observation of an exceptional point in a non-Hermitian metasurface
Contributor:
Park, Sang Hyun;
Lee, Sung-Gyu;
Baek, Soojeong;
Ha, Taewoo;
Lee, Sanghyub;
Min, Bumki;
Zhang, Shuang;
Lawrence, Mark;
Kim, Teun-Teun
Published:
Walter de Gruyter GmbH, 2020
Published in:
Nanophotonics, 9 (2020) 5, Seite 1031-1039
Language:
English
DOI:
10.1515/nanoph-2019-0489
ISSN:
2192-8614;
2192-8606
Origination:
Footnote:
Description:
Abstract Exceptional points (EPs), also known as non-Hermitian degeneracies, have been observed in parity-time symmetric metasurfaces as parity-time symmetry breaking points. However, the parity-time symmetry condition puts constraints on the metasurface parameter space, excluding the full examination of unique properties that stem from an EP. Here, we thus design a general non-Hermitian metasurface with a unit cell containing two orthogonally oriented split-ring resonators (SRRs) with overlapping resonance but different scattering rates and radiation efficiencies. Such a design grants us full access to the parameter space around the EP. The parameter space around the EP is first examined by varying the incident radiation frequency and coupling between SRRs. We further demonstrate that the EP is also observable by varying the incident radiation frequency along with the incident angle. Through both methods, we validate the existence of an EP by observing unique level crossing behavior, eigenstate swapping under encirclement, and asymmetric transmission of circularly polarized light.