Spacetime modulation in floating thin elastic plates

Farhat, Mohamed; Guenneau, Sébastien; Chen, Pai‐Yen; Wu, Ying

doi:10.1103/physrevb.104.014308

Cited by 5 publications

(3 citation statements)

References 56 publications

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“…Modulation of the electric permittivity in space and time was proposed 60 years ago in seminal papers by Simon, Oliner, Hessel and Cassedy [1][2][3][4]. It is observed that when modulating the properties in space and time, band diagrams are rotated in reciprocal space, and this is a general feature observed in all kinds of physical contexts, from optics [5], to acoustics and elastic waves in solids and plates [6], including surface Rayleigh waves [7] and even flexural-gravity waves [8].…”

Section: Introductionmentioning

confidence: 99%

High-order homogenization of the time-modulated wave equation: non-reciprocity for a single varying parameter

Touboul,

Lombard,

Assier

et al. 2024

Proc. R. Soc. A.

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Laminated media with material properties modulated in space and time in the form of travelling waves have long been known to exhibit non-reciprocity. However, when using the method of low-frequency homogenization, it was so far only possible to obtain non-reciprocal effective media when both material properties are modulated in time, in the form of a Willis-coupling (or bi-anisotropy in electromagnetism) model. If only one of the two properties is modulated in time, while the other is kept constant, it was thought impossible for the method of homogenization to recover the expected non-reciprocity since this Willis-coupling coefficient then vanishes. Contrary to this belief, we show that effective media with a single time-modulated parameter are non-reciprocal, provided homogenization is pushed to the second order. This is illustrated by numerical experiments (dispersion diagrams and time-domain simulations) for a bilayered modulated medium.

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Section: Introductionmentioning

confidence: 99%

High-order homogenization of the time-modulated wave equation: non-reciprocity for a single varying parameter

Touboul,

Lombard,

Assier

et al. 2024

Proc. R. Soc. A.

Self Cite

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“…This route, however, faded until this last decade where researchers reinvigorated their interest on the realization of such space time modulated systems, all thanks to the technological progress in fabrication and characterization [13][14][15][16][17][18][19]. Drawing inspiration from photonics, multiples STM based designs were proposed in acoustics [20][21][22][23] and elastodynamics [24][25][26][27][28][29]. In those designs, the mechanical properties of the designed mediums where varied both in space and time to achieve nonreciprocity.…”

Section: Introductionmentioning

confidence: 99%

Nonreciprocal Sound Propagation via Cascaded Time-Modulated Slab Resonators

et al. 2021

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In this work, we demonstrate nonreciprocal acoustic wave transmission in a two cascaded Fabry-Perot like slab resonators undergoing time modulation of their effective density. Phase difference is introduced in the time modulation between the two coupled resonators to produce spatial bias in order to access unidirectional wave propagation. A theoretical model based on plane wave expansion and transfer matrix method is developed to study the Fabry-Perot-based system. The theoretical model allows rapid and precise characterization of the acoustic dispersion, with results in excellent agreement with finite element based numerical simulations. We demonstrate acoustic nonreciprocity behavior for the fundamental acoustic mode, and further show that with proper optimization, the coupled Fabry-Perot based device can achieve nonreciprocal acoustic frequency conversion. This work could inspire designing simple and compact nonreciprocal acoustic devices for efficient wave control.

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“…Recently, time-varying metamaterials were proposed as a promising paradigm [16,17] for designing intriguing functionalities such as luminal devices [18] and/or amplifying structures [19,20]. In the same vein, acoustic metamaterials with moving components have been brought up to enrich the application spectrum [21][22][23][24][25][26].…”

mentioning

confidence: 99%

Sound Waveguiding by Spinning: An Avenue towards Unidirectional Acoustic Spinning Fibers

Farhat¹,

Chen²,

Wu³

2022

Preprint

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Waveguiding in general and acoustic waveguiding in particular are possible at the condition of having a transverse "discontinuity" or modulation of the refractive index. We propose here a radically different approach that relies on imposing spinning on a column of air, leading to high modified acoustic refractive indices for specific azimuthal modes. Such discovery may be leveraged to realize not only the airborne acoustic counterpart of the optical fiber, i.e., the acoustic spinning fiber (ASF), but also nonreciprocal unidirectional waveguiding mechanism, reminiscent of the "acoustic Zeeman effect". The concept is demonstrated in the realm of acoustics, yet it can be applicable to other wave systems, e.g., photonics or elastodynamics.

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Spacetime modulation in floating thin elastic plates

Cited by 5 publications

References 56 publications

High-order homogenization of the time-modulated wave equation: non-reciprocity for a single varying parameter

High-order homogenization of the time-modulated wave equation: non-reciprocity for a single varying parameter

Nonreciprocal Sound Propagation via Cascaded Time-Modulated Slab Resonators

Sound Waveguiding by Spinning: An Avenue towards Unidirectional Acoustic Spinning Fibers

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