José Sánchez-Dehesa

Acoustic cloaking in two dimensions: a feasible approach

This work proposes an acoustic structure feasible to engineer that accomplishes the requirements of acoustic cloaking design recently introduced by Cummer and Schurig (2007 New J. Phys. 9 45). The structure, which consists of a multilayered composite made of two types of isotropic acoustic metamaterials, exactly matches the conditions for the acoustic cloaking. It is also shown that the isotropic metamaterials needed can be made of sonic crystals containing two types of material cylinders, whose elastic parameters should be properly chosen in order to satisfy (in the homogenization limit) the acoustic properties under request. In contrast to electromagnetic cloaking, the structure here proposed verifies the acoustic cloaking in a wide range of wavelengths; its performance is guaranteed for any wavelength above a certain cutoff defined by the homogenization limit of the sonic crystal employed in its fabrication.

Acoustic metamaterials for new two-dimensional sonic devices

It has been shown that two-dimensional arrays of rigid or fluidlike cylinders in a fluid or a gas define, in the limit of large wavelengths, a class of acoustic metamaterials whose effective parameters (sound velocity and density) can be tailored up to a certain limit. This work goes a step further by considering arrays of solid cylinders in which the elastic properties of cylinders are taken into account. We have also treated mixtures of two different elastic cylinders. It is shown that both effects broaden the range of acoustic parameters available for designing metamaterials. For example, it is predicted that metamaterials with perfect matching of impedance with air are now possible by using aerogel and rigid cylinders equally distributed in a square lattice. As a potential application of the proposed metamaterial, we present a gradient index lens for airborne sound (i.e. a sonic Wood lens) whose functionality is demonstrated by multiple scattering simulations.

Surface Shape Resonances in Lamellar Metallic Gratings

The specular reflectivity of lamellar gratings of gold with grooves

Anisotropic mass density by two-dimensional acoustic metamaterials

0.5\ensuremath{\mu}\mathrm{m}

Sound focusing by gradient index sonic lenses

wide separated by a distance of

Omnidirectional broadband acoustic absorber based on metamaterials

3.5\ensuremath{\mu}\mathrm{m}

Sonic gradient index lens for aqueous applications

was measured on the 2000\char21{}

Synthesis and photonic bandgap characterization of polymer inverse opals

7000{\mathrm{cm}}^{\ensuremath{-}1}

Localized surface plasmons in lamellar metallic gratings

spectral range for p-polarized light. Experimental evidence of the excitation of electromagnetic surface shape resonances for optical frequencies is given. In these resonances the electric field is highly localized inside the grooves and is almost zero in all other regions. For grooves of depth equal to

Integrated optical devices design by genetic algorithm

0.6\ensuremath{\mu}\mathrm{m}