Enhanced Broadband Manipulation of Acoustic Vortex Beams Using 3-bit Coding Metasurfaces through Topological...

Area of Science:

• Acoustics
• Materials Science
• Wave Physics

Background:

• Acoustic coding metasurfaces (ACMs) offer versatile control over acoustic waves through programmable coding sequences.
• Broadband capabilities enhance ACM versatility, enabling more complex acoustic functions with fewer units compared to traditional metasurfaces.
• Multi-bit designs allow for precise phase control of sound waves.

Purpose of the Study:

• To develop novel 3-bit broadband reflected acoustic coding metasurfaces (BACMs) for advanced acoustic manipulation.
• To systematically design these BACMs using a bottom-up topology optimization method.
• To explore their potential in creating acoustic vortices and manipulating acoustic beams.

Main Methods:

• Bottom-up topology optimization for systematic design of 3-bit BACMs.
• Design of eight coding units achieving a constant 45° phase difference across a broad frequency range.
• Utilizing convolution methods for constructing vortex-focusing and vortex beam manipulation metasurfaces.

Main Results:

• Successful development of 3-bit BACMs with eight coding units.
• Demonstration of a constant 45° phase difference across all units in a broad frequency range.
• Construction of acoustic vortex metasurfaces and strategies for vortex beam manipulation.

Conclusions:

• The developed 3-bit BACMs provide precise control over acoustic waves, enabling complex functionalities.
• These metasurfaces show significant potential for applications in acoustic particle suspension and acoustic communication.
• The design methodology facilitates the creation of advanced acoustic devices for diverse applications.