Optical Characterization of Phononic Crystals in the Time Domain

Matsuda, Osamu; Wright, Oliver B.

doi:10.1007/978-1-4614-9393-8_7

Cited by 1 publication

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References 46 publications

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“…Acoustic waveguides based on phononic crystals [1][2][3][4][5][6][7][8][9][10] have been attracting increasing attention for controlling wave transmission along designed paths at desired operating frequencies [11][12][13][14] using a band-engineering scheme similar to the electronic structure design in semiconductors. However, the practical application of acoustic waveguides using phononic crystals has been hindered by inevitable transmission loss owing to the scattering of sound waves at defects and bending in the waveguide [13,14].…”

Section: Introductionmentioning

confidence: 99%

Design and Robustness Evaluation of Valley Topological Elastic Wave Propagation in a Thin Plate with Phononic Structure

Kataoka¹,

Misawa²,

Tsuruta³

2022

Symmetry

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Based on the concept of band topology in phonon dispersion, we designed a topological phononic crystal in a thin plate for developing an efficient elastic waveguide. Despite that various topological phononic structures have been actively proposed, a quantitative design strategy of the phononic band and its robustness assessment in an elastic regime are still missing, hampering the realization of topological acoustic devices. We adopted a snowflake-like structure for the crystal unit cell and determined the optimal structure that exhibited the topological phase transition of the planar phononic crystal by changing the unit cell structure. The bandgap width could be adjusted by varying the length of the snow-side branch, and a topological phase transition occurred in the unit cell structure with threefold rotational symmetry. Elastic waveguides based on edge modes appearing at interfaces between crystals with different band topologies were designed, and their transmission efficiencies were evaluated numerically and experimentally. The results demonstrate the robustness of the elastic wave propagation in thin plates. Moreover, we experimentally estimated the backscattering length, which measures the robustness of the topologically protected propagating states against structural inhomogeneities. The results quantitatively indicated that degradation of the immunization against the backscattering occurs predominantly at the corners in the waveguides, indicating that the edge mode observed is a relatively weak topological state.

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