Systematic realization of double-zero-index phononic crystals with hard inclusions

Area of Science:

• Acoustics
• Materials Science
• Condensed Matter Physics

Background:

• Double-zero-index phononic crystals (ZIPCs) offer unique wave manipulation properties.
• Experimental realization of ZIPCs is challenging, especially with hard inclusions.
• Existing methods for soft inclusions do not directly apply to hard-inclusion systems.

Purpose of the Study:

• To establish conditions for realizing ZIPCs with hard inclusions.
• To develop a systematic design methodology for hard-inclusion ZIPCs.
• To experimentally validate the design method with a practical application.

Main Methods:

• Utilizing homogenization based on effective medium theory.
• Discovering essential conditions for hard-inclusion ZIPC realization.
• Optimizing crystal design through the proposed systematic methodology.

Main Results:

• A systematic design process for hard-inclusion ZIPCs was established.
• The methodology enabled the optimization of a double-zero-index phononic crystal.
• An experimentally realized double-zero-index phononic crystal for ultrasonic wave collimation was demonstrated.

Conclusions:

• The developed methodology provides a systematic approach to designing hard-inclusion ZIPCs.
• This work overcomes experimental limitations, broadening the scope of ZIPC applications.
• The successful realization of an ultrasonic wave collimator validates the proposed design process.