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Acoustic Bloch oscillations in a two-dimensional phononic crystal
Zhaojian He1, Shasha Peng, Feiyan Cai
1Key Lab of Acoustic and Photonic Materials and Devices of Ministry of Education and Department of Physics, Wuhan University, Wuhan 430072, China.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 1, 2008
Summary
Researchers observed acoustic Bloch oscillations at megahertz frequencies in a 2D phononic crystal. This demonstrates oscillatory motion using engineered cavities, paving the way for novel acoustic devices.
Area of Science:
- Acoustics
- Condensed Matter Physics
- Materials Science
Background:
- Phononic crystals are engineered materials that control sound wave propagation.
- Acoustic Bloch oscillations are analogous to electronic Bloch oscillations in periodic potentials.
- Observing these oscillations at high frequencies is challenging.
Purpose of the Study:
- To experimentally demonstrate acoustic Bloch oscillations at megahertz frequencies.
- To investigate the creation of acoustic Wannier-Stark ladders in a phononic crystal.
- To explore the oscillatory motion of acoustic pulses in engineered structures.
Main Methods:
- Fabrication of a two-dimensional phononic crystal with periodically arrayed cavities.
- Gradual decrease in cavity width along one direction to create a potential gradient.
- Numerical simulations and experimental measurements of acoustic pulse propagation.
Main Results:
- Observation of acoustic Bloch oscillations at megahertz frequencies.
- Successful creation of acoustic Wannier-Stark ladders in the frequency domain.
- Demonstration of oscillatory motion of an incident Gaussian pulse within the phononic crystal.
Conclusions:
- Acoustic Bloch oscillations are achievable at megahertz frequencies in designed phononic crystals.
- Engineered cavity gradients effectively create acoustic Wannier-Stark ladders.
- The findings validate theoretical predictions and open avenues for acoustic device applications.
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