Experimental demonstration of three-dimensional broadband underwater acoustic carpet cloak

Quasi isotropic underwater acoustic carpet cloak based on latticed pentamode metafuid

In this work, we present a practical design of quasi isotropic underwater acoustic carpet cloak with pentamode microstructure. The quasi conformal transformation is not only used to obtain the required parameters, but also used to deform the retrieved regular pentamode material structure to the desired carpet, during which the effective parameters can be considered as not being affected too much. The nice and broadband cloak effect shows the success of the design. This work will contribute to the experimental demonstration of pentamode acoustic carpet cloak. Moreover, the technique in this wor…

Engineered diffraction gratings for acoustic cloaking

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 c…

用于水下隐身的减重近隐身衣

Reduced-weight near-cloaks for underwater invisibility

针对水下声学隐身衣难以同时保持浮力和隐身性能的问题，本文结合程函隐身衣与近隐身衣，并引入径向失配设计，在减轻质量的同时维持散射抑制效果。

Ultrathin carpet cloak enabled by infinitely anisotropic medium

Thanks to the pioneering studies conducted on the fields of transformation optics (TO) and metasurfaces, many unprecedented devices such as invisibility cloaks have been recently realized. However, each of these methods has some drawbacks limiting the applicability of the designed devices for real-life scenarios. For instance, TO studies lead to bulky coating layer with the thickness that is comparable to, or even larger than the dimension of the concealed object. In this paper, based on the coordinate transformation, an ultrathin carpet cloak is proposed to hide objects with arbitrary shape a…

Non-Closed Acoustic Cloak Enabled by Sequential-Step Linear Coordinate Transformations

Hitherto acoustic cloaking devices, which conceal objects externally, have depended on the objects' characteristics. Despite previous works, we design cloaking device placed neighbor an arbitrary object and makes it invisible without the need to make it enclosed. Applying sequential linear coordinate transformations, leads to a non-closed acoustic cloak (NCAC) with homogeneous materials that creates an open invisible region. We propose a non-closed carpet cloak to conceal objects on a reflecting plane. Numerical simulations verify the cloaking effect, which is completely independent of the geo…

Ultra-thin Underwater Acoustic Metasurface with Multiply Resonant Units

This paper describes a new kind of acoustic metasurface with multiply resonant units, which have previously been used to induce multiple resonances and effectively produce negative mass density and bulk/shear moduli. The proposed acoustic metasurface can be constructed using real materials and does not rely on an ideal rigid material. Therefore, it can work well in a water background. The thickness of the acoustic metasurface is about two orders of magnitude smaller than the acoustic wavelength in water. The design of a unit group is proposed to avoid the phase discretization becoming too fine…