Asymmetric acoustic energy transport in non-Hermitian metamaterials

Thevamaran, Ramathasan; Branscomb, Richard Massey; Makri, Eleana; Anzel, Paul; Christodoulides, Demetrios N.; Thomas, Edwin L.

doi:10.1121/1.5114919

Cited by 16 publications

(11 citation statements)

References 36 publications

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“…Thereby, we constitute a framework to analyze and construct degeneracies by real perturbations, although its numerical study is beyond our scope here [38]. It has already been established that systems exhibit extraordinary behavior in the vicinity of non-Hermitian degeneracies, such as ultra-sensitivity [39] (as we also demonstrate in the sequel), Berry phase acquiring [40], and asymmetric scattering properties [41,42]. Accordingly, our framework offers an approach to achieve such extraordinary wave phenomena by designing non-Hermitian degeneracies in simple elastic systems, without the need for external gain and loss as in the works mentioned earlier.…”

Section: Introductionmentioning

confidence: 99%

Linking Scalar Elastodynamics and Non-Hermitian Quantum Mechanics

Gal¹,

Moiseyev²

2020

Phys. Rev. Applied

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Recent years have seen a fascinating pollination of ideas from quantum theories to elastodynamics-a theory that phenomenologically describes the time-dependent macroscopic response of materials.Here, we open route to transfer additional tools from non-Hermitian quantum mechanics. We begin by identifying the differences and similarities between the one-dimensional elastodynamics equation and the time-independent Schrödinger equation, and finding the condition under which the two are equivalent. Subsequently, we demonstrate the application of the non-Hermitian perturbation theory to determine the response of elastic systems; calculation of leaky modes and energy decay rate in heterogenous solids with open boundaries using a quantum mechanics approach; and construction of degeneracies in the spectrum of these assemblies. The latter result is of technological importance, as it introduces an approach to harness extraordinary wave phenomena associated with non-Hermitian degeneracies for practical devices, by designing them in simple elastic systems. As an example of such application, we demonstrate how an assembly of elastic slabs that is designed with two degenerate shear states according to our scheme, can be used for mass sensing with enhanced sensitivity by exploiting the unique topology near the exceptional point of degeneracy. arXiv:1910.07306v2 [cond-mat.soft]

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Section: Introductionmentioning

confidence: 99%

Linking Scalar Elastodynamics and Non-Hermitian Quantum Mechanics

Gal¹,

Moiseyev²

2020

Phys. Rev. Applied

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“…Metamaterials, a kind of artificial structures, can be elaborately designed to acquire extraordinary and unique properties including negative refraction, perfect lens, giant chiral response, and nonlinearity (Shelby et al, 2001). Metamaterials can be also extended into diverse fields, such as electromagnetism, acoustics, and mechanics (Deng et al, 2019;Fan et al, 2019;Thevamaran et al, 2019). Chiral objects lack mirror symmetry, and it cannot superimpose with its mirror image through planar translation or rotation.…”

Section: Introductionmentioning

confidence: 99%

Optical Properties and Dynamic Extrinsic Chirality of Structured Monolayer Black Phosphorus

Sun

Wang

et al. 2022

Front. Mater.

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Chiral metamaterials have drawn increasing attention due to their strong chiral responses. Monolayer black phosphorus is a tunable two-dimensional material with anisotropy that plays an important role in a variety of fields such as chirality and polarization control. In this work, we propose a metamaterial with structured monolayer black phosphorus to manipulate the transmission properties of circularly polarized waves. The metamaterial exhibits strong circular dichroism and circular birefringence effects depending on oblique incidence of the circularly polarized wave and has a weaker circular conversion dichroism effect as well. Moreover, this work also investigates effects of different chiral phenomena of the metamaterial on various structural parameters as well as incident angles and the electron concentration. It has been proved that the electron concentration of monolayer black phosphorus can dynamically tune the chirality properties. Remarkably, the non-zero pure optical activity always occurs at one certain frequency regardless of the elevation angle and the azimuthal angle. The proposed framework provides opportunities for designing meta-devices with monolayer black phosphorus and practical potentials for novel and high-performance infrared metamaterials.

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“…The evolution of localized acoustic metamaterials has bestowed uncommon soundwave properties and applications. It opens up a platform for sound control, such as the manipulation of effective material properties [12], parity-time symmetric devices and sensors [13,14], frequency-selective acoustic metasurfaces and adaptive wavefield shaping [15,16], * romain.fleury@epfl.ch constant amplitude sound waves in disordered media [17], acoustic lenses with superresolution and imaging [18], asymmetric energy transport [19], analog computing [20], acoustic bianisotropy [21], and the realization of real-time and broadband acoustic cloaking and holography [22]. Although passive acoustic metamaterials are used to provide anomalous scattering properties and extreme values of constitutive parameters, they are unavoidably prone to losses and generally display narrowband functionalities, as direct consequences of the Kramers-Kronig relations, which must hold in any passive and causal material.…”

Section: Introductionmentioning

confidence: 99%

Active Acoustic Resonators with Reconfigurable Resonance Frequency, Absorption, and Bandwidth

et al. 2019

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Acoustic resonators play a key role in the development of subwavelength-sized technologies capable of interacting with airborne audible sound, from its emission and absorption to its manipulation and processing. Specifically, artificial acoustic media made from an ensemble of subwavelength resonators, namely, acoustic metamaterials and metasurfaces, have enabled sound manipulation possibilities well beyond what is typically achievable using natural materials. Yet, the transition of such concepts from physics-driven explorations to practical applications has been drastically hindered by the major difficulty in controlling the resonance frequency, absorption level, and bandwidth of these resonators, making acoustic metamaterials often too narrowband, or sensitive to disorder and absorption losses. Here, we demonstrate the relevance of active electroacoustic resonators to address such limitations. We propose a feedback control scheme for loudspeakers (used as acoustic scatterers), which involves passband current control based on real-time sensing and processing of the pressure signal by field-programmable gate-array technologies. We demonstrate externally reconfigurable subwavelength acoustic resonators with independently tunable levels of absorption (including near-zero and near-one), bandwidth, and resonance frequency. We believe that this work demonstrates a viable route to overcome the current limitations of metamaterials and enable their practical applications.

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Asymmetric acoustic energy transport in non-Hermitian metamaterials

Cited by 16 publications

References 36 publications

Linking Scalar Elastodynamics and Non-Hermitian Quantum Mechanics

Linking Scalar Elastodynamics and Non-Hermitian Quantum Mechanics

Optical Properties and Dynamic Extrinsic Chirality of Structured Monolayer Black Phosphorus

Active Acoustic Resonators with Reconfigurable Resonance Frequency, Absorption, and Bandwidth

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