Published in

IOP Publishing, New Journal of Physics, 6(23), p. 063079, 2021

DOI: 10.1088/1367-2630/ac09c9

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Universal route for the emergence of exceptional points in PT-symmetric metamaterials with unfolding spectral symmetries

Journal article published in 2021 by Yanghao Fang ORCID, Tsampikos Kottos ORCID, Ramathasan Thevamaran ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Abstract We introduce a class of parity-time symmetric elastodynamic metamaterials (Ed-MetaMater) whose Hermitian counterpart exhibits unfolding (fractal) spectral symmetries. Our study reveals a scale-free formation of exceptional points in those Ed-MetaMaters whose density is dictated by the fractal dimension of their Hermitian spectra. We demonstrate this scale-free EP-formation in a quasi-periodic Aubry-Harper Ed-MetaMater, a geometric H-tree-fractal Ed-MetaMater, and an aperiodic Fibonacci Ed-MetaMater—each having a specific fractal spectrum—using finite element models and establish a universal route for EP-formation via a coupled mode theory model with controllable fractal spectrum. This universality may enable the rational design of novel Ed-MetaMater for hypersensitive sensing and elastic wave control.