Double-zero-index structural waveguides

Abstract

We report on the theoretical and experimental realization of a double-zero-index elastic waveguide and on the corresponding acoustic cloacking and supercoupling effects. The proposed waveguide uses geometric tapers in order to induce Dirac-like cones at $\vec{k}=0$ due to accidental degeneracy. The nature of the degeneracy is explored by a $k\cdot p$ perturbation method adapted to thin structural waveguides. Results confirm the linear nature of the dispersion around the degeneracy and the possibility to map the material to effective medium properties. Effective parameters, numerically extracted using boundary medium theory, confirm that the phononic waveguide maps into a double zero index material. Numerical and experimental results confirm the expected cloacking and supecoupling effects typical of zero index materials.

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Cited by in corpus (8)

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• Real-Time Steering of Curved Sound Beams in a Feedback-based Topological Acoustic Metamaterial
• Weyl points and topological surface states in a three-dimensional elastic lattice
• Stopping and reversing sound via dynamic dispersion tuning in a phononic metamaterial
• Spin-1 Weyl Point and Surface Arc State in a Chiral Phononic Crystal
• Band Structure and Effective Properties of One-Dimensional Thermoacoustic Bloch Waves
• On the instabilities of intrinsic thermoacoustic modes in a thermoacoustic waveguide with anechoic terminations