Extreme acoustic metamaterial by coiling up space

Area of Science:

• Acoustics
• Metamaterials Science
• Wave Physics

Background:

• Acoustic metamaterials offer unique wave manipulation capabilities.
• Achieving extreme constitutive parameters like double negativity and near-zero density is challenging.
• Existing methods often rely on resonant structures, limiting bandwidth and scalability.

Purpose of the Study:

• To demonstrate a novel method for constructing 2D acoustic metamaterials.
• To achieve a frequency-dispersive spectrum with extreme constitutive parameters.
• To explore applications such as negative refraction and tunneling.

Main Methods:

• Utilizing curled perforations to coil up space in a 2D structure.
• Analyzing the frequency dispersive spectrum of the resulting metamaterial.
• Employing numerical simulations to demonstrate device functionalities.

Main Results:

• The constructed metamaterial exhibits double negativity, near-zero density, and a large refractive index.
• Band foldings are observed in the effective medium regime without resonant structures.
• Numerical demonstrations of negative refraction and tunneling are successful.

Conclusions:

• Coiling space via curled perforations is an effective strategy for acoustic metamaterial design.
• This approach offers a pathway to broadband acoustic devices with extreme parameters.
• The principle is scalable to three dimensions, broadening potential applications.