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Confined acoustic line modes within a glide-symmetric waveguide
Daniel B Moore1, Gareth P Ward2, John D Smith3
1Electromagnetic and Acoustic Materials Group, Department of Physics and Astronomy, University of Exeter, Stocker Road, Devon, EX4 4QL, UK. dm680@exeter.ac.uk.
Scientific Reports
|June 29, 2022
Summary
Researchers studied acoustic line-modes in glide-symmetric waveguides. They found these modes have tunable hybrid properties and constant group velocity, with band gaps reappearing upon breaking glide symmetry.
Area of Science:
- Acoustic Metamaterials
- Solid-State Physics
Background:
- Confined acoustic modes in periodic structures are crucial for wave manipulation.
- Glide-symmetric waveguides offer unique properties due to their specific symmetry.
Purpose of the Study:
- To investigate the characteristics of confined coupled acoustic line-modes in glide-symmetric waveguides.
- To explore the tunability of these modes and the impact of glide symmetry.
- To understand the reappearance of band gaps when symmetry is broken.
Main Methods:
- Theoretical analysis of acoustic wave propagation in a waveguide with periodic holes.
- Numerical simulations to study mode properties and band structures.
- Parameter variation to investigate the effect of surface spacing and symmetry breaking.
Main Results:
- Identified hybrid acoustic line-modes with combined symmetric and anti-symmetric properties.
- Observed near-constant group velocity over a wide frequency range due to the absence of a band gap at the Brillouin zone boundary.
- Demonstrated that the hybrid character of these modes is tunable by adjusting the spacing between the waveguide surfaces.
- Showed that breaking glide symmetry leads to the reappearance of band gaps.
Conclusions:
- The studied acoustic line-modes exhibit tunable hybrid characteristics beneficial for waveguiding applications.
- Glide symmetry plays a critical role in achieving broadband, constant group velocity propagation.
- Breaking glide symmetry offers a mechanism to reintroduce band gaps, enabling frequency selectivity.
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