Engineered diffraction gratings for acoustic cloaking

TL;DR

This paper demonstrates how engineered diffraction gratings can be used to create effective acoustic cloaks by redirecting incident sound waves, simplifying design, and achieving excellent scattering cancellation through both simulations and experiments.

Contribution

It introduces a novel approach using diffraction gratings for acoustic cloaking, including design principles and experimental validation.

Findings

Achieved retroreflection to cloak objects over rigid surfaces.

Designed thin acoustic carpet cloaks with simple axisymmetric gratings.

Validated cloaking performance through full wave simulations and experiments.

Abstract

We show that engineered diffraction gratings can considerably simplify the design and performance of acoustic devices. Acoustic reflecting gratings based on rectangular cavities drilled on an acoustically rigid surface are designed in such a way that all the incident energy is channeled towards the diffracted mode traveling in the oposite direction of the incident field (retroreflection effect), and this effect is used to cloak an object placed over a rigid surface. Axisymmetric gratings consisting in rigid surfaces with just one groove per unit cell are used to design acoustic thin acoustic carpet cloaks. Finally, full wave numerical simulations are performed and a conical carpet cloak is experimentally tested, showing an excellent scattering cancellation effect.