Time reversal focusing in the audible range using a tunable sonic crystal

Area of Science:

• Acoustics
• Wave phenomena
• Materials science

Background:

• Time reversal (TR) focusing typically requires chaotic cavities or disordered media for acoustic wave decorrelation.
• Sonic crystals, due to their periodic nature, were previously considered unsuitable for effective TR focusing.

Purpose of the Study:

• To experimentally demonstrate a tunable sonic crystal for single-channel TR focusing.
• To compare the TR focusing capabilities of the tunable sonic crystal with disordered media.
• To investigate the tunability and robustness of TR focusing in the sonic crystal.

Main Methods:

• Experimental realization of a tunable sonic crystal.
• Utilizing a single channel for TR focusing.
• Analysis of TR focusing amplitudes and pulse characteristics.
• Perturbation analysis of sonic crystal configurations.

Main Results:

• Achieved single-channel TR focusing amplitudes comparable to disordered scattering media in the audible range.
• Demonstrated the ability to switch time-reversed pulses on and off by altering the crystal's geometry.
• Showcased that high temporal and spatial contrasts of TR pulses are maintained only near the original configuration.

Conclusions:

• Tunable sonic crystals are viable for achieving significant time reversal focusing.
• The tunable nature offers control over TR focusing by modifying the system's geometry.
• Robustness analysis highlights the sensitivity of high-contrast TR focusing to precise sonic crystal configurations.