Tunneling of Elastic Waves in a Tapered Waveguide

Fuente: arXiv
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Main Authors: Charau, Alexandre Yoshitaka, Laurent, Jérôme, Valier-Brasier, Tony
Format: Preprint
Published: 2026
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author Charau, Alexandre Yoshitaka
Laurent, Jérôme
Valier-Brasier, Tony
author_facet Charau, Alexandre Yoshitaka
Laurent, Jérôme
Valier-Brasier, Tony
contents Understanding how evanescent modes mediate energy transfer in tapered elastic waveguides is of paramount interest, as it unlocks new strategies for wave control and manipulation. Evanescent modes play a crucial role in energy localization and in the emergence of thickness resonances. We report the first unambiguous experimental evidence of Lamb mode tunneling near turning points, revealing how energy can traverse an evanescent barrier and recover its propagative nature after a finite transit time. Focusing on waveguides with linearly varying thickness, we show that the $S_2$ mode becomes evanescent over a narrow frequency band, enabling a tunnelinglike phenomenon. Our study demonstrates that the barrier width is governed by the elastic properties of the material, particularly the Poisson's ratio, within a confined range bordering the Dirac cone. Numerical results exhibit excellent agreement with predictions from the Wentzel-Kramers-Brillouin approximation. These findings provide compelling evidence that, for a specific barrier width, evanescent modes mediate energy transfer across regions classically forbidden to propagating waves, revealing the mechanisms governing transmission, localization, and mode conversion in structured or corrugated elastic waveguides.
format Preprint
id arxiv_https___arxiv_org_abs_2601_06855
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Tunneling of Elastic Waves in a Tapered Waveguide
Charau, Alexandre Yoshitaka
Laurent, Jérôme
Valier-Brasier, Tony
Classical Physics
Understanding how evanescent modes mediate energy transfer in tapered elastic waveguides is of paramount interest, as it unlocks new strategies for wave control and manipulation. Evanescent modes play a crucial role in energy localization and in the emergence of thickness resonances. We report the first unambiguous experimental evidence of Lamb mode tunneling near turning points, revealing how energy can traverse an evanescent barrier and recover its propagative nature after a finite transit time. Focusing on waveguides with linearly varying thickness, we show that the $S_2$ mode becomes evanescent over a narrow frequency band, enabling a tunnelinglike phenomenon. Our study demonstrates that the barrier width is governed by the elastic properties of the material, particularly the Poisson's ratio, within a confined range bordering the Dirac cone. Numerical results exhibit excellent agreement with predictions from the Wentzel-Kramers-Brillouin approximation. These findings provide compelling evidence that, for a specific barrier width, evanescent modes mediate energy transfer across regions classically forbidden to propagating waves, revealing the mechanisms governing transmission, localization, and mode conversion in structured or corrugated elastic waveguides.
title Tunneling of Elastic Waves in a Tapered Waveguide
topic Classical Physics
url https://arxiv.org/abs/2601.06855