LinkNotes: Metamaterials To Develop Invisibility Cloaks

Scientists Working on Invisibility Cloak

The Imperial College of London and the University of Southampton have been awarded a £4.9 million grant from the Leverhulme Trust to further research "metamaterials" that could hopefully bend light away as it reflects from the surface, tricking the human eye into believing an item made of metamaterials is not there. To create the materials, scientists have to alter the structure of an already existing material using complex nanopatterns. In other words, eerily floating chess pieces for everyone!

clipped from www.dailymail.co.uk

We may be seeing Harry Potter's invisibility suit sooner than we think...

Fiction made real? Harry Potter goes invisible in the 'Goblet of Fire'

A photo of 'meta-material', which can deflect microwave beams so they flow around a 'hidden' object

clipped from www3.imperial.ac.uk

£4.9 million to develop metamaterials for 'invisibility cloaks' and 'perfect lenses'
Imperial receives major new funding grant from The Leverhulme Trust - News Release

The new grant is one of two The Leverhulme Trust is awarding for 'embedding emerging disciplines'. The project team is led by two of Imperial College London's Professors: Professor Sir John Pendry, a world-leading physicist and pioneer in the field, who first proposed that metamaterials could be used to build an invisibility 'cloak' in 2006, and Professor Stefan Maier who is a leading experimentalist in the field of plasmonics. Also collaborating in the project is Professor Nikolay Zheludev's team at the University of Southampton.

clipped from physics.aps.org

Taking the wraps off cloaking

$(Top) A hot desert surface causes a refractive index gradient in the air above, causing rays of light to be refracted continuously to form a reflection in the road and hence the appearance of water. (Bottom) Similarly, a graded refractive index cloak can guide light around a hidden object so that an observer sees only that which is behind the cloak.$

Illustration: Top: www.dreamstime.com; Bottom: Pendry et al. [7]

$(Top left) A ray of light in free space travels in a straight line. The undistorted coordinate system is shown. (Top right) The coordinates are transformed to exclude the cloaked region. Trajectories of rays are pinned to the coordinate mesh and therefore avoid the cloaked region, returning to their original path after traversing the cloak. (Bottom) In contrast, this cloaking scheme operates by cancelling scattering due to the hidden object. Here we show a high-refractive-index sphere hidden by$

A ray of light in free space travels in a straight line. The undistorted coordinate system is shown. (Top right) The coordinates are transformed to exclude the cloaked region. Trajectories of rays are pinned to the coordinate mesh and therefore avoid the cloaked region, returning to their original path after traversing the cloak.

$(Top left) The first implementation of a cloak: resonant elements, shown inset, are incorporated in a metamaterial and tuned to give a magnetic response graded from the inner to outer radius. Dimensions are shown in mm. The cloak is designed to operate at $8.5\ \textrm{GHz}$. (Bottom left) A proposed design for an optical version of the cloak, incorporating metal wires in a dielectric host and designed to operate at $632.8\ \textrm{nm}$ in a cloak approximately 4 microns in diameter. The latter$

Illustration: Top left: Schurig et al. [11]; bottom left: Smolyaninov et al. [21]; top and bottom right: Valentine et al. [19]

Illustration: Torrent and Sánchez-Dehesa [28]

Figure 5: (Left) Schematic view of the acoustic cloaking shell consisting of two different materials of the same thicknesses arranged in a cylindrical multilayered structure. (Right) Pressure map for a planar wave incident on a multilayer structure comprising 200 layers.