Research team at City University of Hong Kong (CityU) has discovered a new type of sound wave: The airborne sound wave vibrates transversely and carries both spin and orbital angular momentum like light does. The findings shattered scientists’ previous beliefs about the sound wave.
Researchers designed a type of artificial material called “micropolar metamaterial” to implement this idea, which appears like a complex network of resonators. Air behaves like an elastic material inside the micropolar metamaterial.
The findings demonstrated that airborne sound, or sound in fluids, can be a transverse wave and carry full vector properties such as spin angular momentum the same as light does. This may have applications in acoustic communications, acoustic sensing and imaging.
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