Electromagnetic-acoustic biphysical cloak designed through topology optimization.

Area of Science:

• Multiphysics
• Metamaterials
• Wave physics

Background:

• Existing invisibility cloaking strategies typically control only a single physical phenomenon (e.g., electromagnetic or acoustic waves).
• Achieving cloaking for multiple wave types simultaneously, such as electromagnetic and acoustic, presents significant challenges with current transformation theory and metamaterial approaches.

Purpose of the Study:

• To design and present a biphysical cloak capable of cloaking against multiple wave types.
• To demonstrate triple-wave cloaking capabilities for specific electromagnetic polarizations (Ez- and Hz-) and acoustic waves.

Main Methods:

• Development of topology optimization techniques tailored for controlling both electromagnetic and acoustic wave propagation.
• Design of biphysical cloak structures capable of canceling scattering for three distinct wave types.

Main Results:

• The topology-optimized biphysical cloak successfully cancels scattering for Ez-polarized, Hz-polarized, and acoustic waves.
• The cloak reproduces original propagating waves, effectively rendering the cloaked object invisible to these three wave types.
• Demonstrated cloaking structures effective for multiple incident directions and varying wavelengths of electromagnetic and acoustic waves.

Conclusions:

• Topology optimization provides a viable multidisciplinary approach for designing advanced biphysical cloaks.
• The developed biphysical cloak offers unprecedented capabilities for simultaneous invisibility across different wave phenomena and wavelengths.