Up until now, the invisibility cloaks put forward by scientists have been fairly bulky contraptions – an obvious flaw for those interested in Harry Potter-style applications.
However, researchers from the US have now developed a cloak that is just micrometres thick and can hide three-dimensional objects from microwaves in their natural environment, in all directions and from all of the observers' positions.
Presenting their study today, 26 March, in the Institute of Physics and German Physical Society's New Journal of Physics, the researchers, from the University of Texas at Austin, have used a new, ultrathin layer called a "metascreen".
The metascreen cloak was made by attaching strips of 66 µm-thick copper tape to a 100 µm-thick, flexible polycarbonate film in a fishnet design. It was used to cloak an 18 cm cylindrical rod from microwaves and showed optimal functionality when the microwaves were at a frequency of 3.6 GHz and over a moderately broad bandwidth.
The researchers also predict that due to the inherent conformability of the metascreen and the robustness of the proposed cloaking technique, oddly shaped and asymmetrical objects can be cloaked with the same principles.
Objects are detected when waves – whether they are sound, light, x-rays or microwaves – rebound off its surface. The reason we see objects is because light rays bounce off their surface towards our eyes and our eyes are able to process the information.
Whilst previous cloaking studies have used metamaterials to divert, or bend, the incoming waves around an object, this new method, which the researchers dub "mantle cloaking", uses an ultrathin metallic metascreen to cancel out the waves as they are scattered off the cloaked object.
"When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation," said co-author of the study Professor Andrea Alu.
"The advantages of the mantle cloaking over existing techniques are its conformability, ease of manufacturing and improved bandwidth. We have shown that you don't need a bulk metamaterial to cancel the scattering from an object – a simple patterned surface that is conformal to the object may be sufficient and, in many regards, even better than a bulk metamaterial."
Last year, the same group of researchers were the first to successfully cloak a 3D object in another paper published in New Journal of Physics, using a method called "plasmonic cloaking", which used more bulky materials to cancel out the scattering of waves.
Moving forward, one of the key challenges for the researchers will be to use "mantle cloaking" to hide an object from visible light.
"In principle this technique could also be used to cloak light," continued Professor Alu.
"In fact, metascreens are easier to realize at visible frequencies than bulk metamaterials and this concept could put us closer to a practical realization. However, the size of the objects that can be efficiently cloaked with this method scales with the wavelength of operation, so when applied to optical frequencies we may be able to efficiently stop the scattering of micrometer-sized objects.
"Still, we have envisioned other exciting applications using the mantle cloak and visible light, such as realizing optical nanotags and nanoswitches, and noninvasive sensing devices, which may provide several benefits for biomedical and optical instrumentation."
From Tuesday 26 March, this paper can be downloaded from http://iopscience.iop.org/1367-2630/15/3/033037/article.
Notes to Editors
1. For further information, a full draft of the journal paper or contact with one of the researchers, contact IOP Publishing Press Officer, Michael Bishop:
Tel: 0117 930 1032
IOP Publishing Journalist Area
2. The IOP Publishing Journalist Area (http://journalists.iop.org/journalistLogin) gives journalists access to embargoed press releases, advanced copies of papers, supplementary images and videos. In addition to this, a weekly news digest is uploaded into the Journalist Area every Friday, highlighting a selection of newsworthy papers set to be published in the following week.
Login details will also give free access to IOPscience, IOP Publishing's journal platform.
To apply for a free subscription to this service, please email Michael Bishop, IOP Press Officer, firstname.lastname@example.org, with your name, organisation, address and a preferred username.
Demonstration of an ultra-low profile cloak for scattering suppression of a finite-length rod in free space
3. The published version of the paper "Demonstration of an ultra-low profile cloak for scattering suppression of a finite-length rod in free space" (J C Soric et al 2013 New J. Phys. 15 033037) will be freely available online from Tuesday 26 March. It will be available at http://iopscience.iop.org/1367-2630/15/3/033037/article.
New Journal of Physics
4. New Journal of Physics publishes across the whole of physics, encompassing pure, applied, theoretical and experimental research, as well as interdisciplinary topics where physics forms the central theme. All content is permanently free to read and the journal is funded by an article publication charge.
5. IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. IOP Publishing is central to the Institute of Physics (IOP), a not-for-profit society. Any financial surplus earned by IOP Publishing goes to support science through the activities of IOP. Beyond our traditional journals programme, we make high-value scientific information easily accessible through an ever-evolving portfolio of community websites, magazines, conference proceedings and a multitude of electronic services. Focused on making the most of new technologies, we're continually improving our electronic interfaces to make it easier for researchers to find exactly what they need, when they need it, in the format that suits them best. Go to http://ioppublishing.org/
The Institute of Physics
6. The Institute of Physics is a leading scientific society promoting physics and bringing physicists together for the benefit of all.
It has a worldwide membership of around 40 000 comprising physicists from all sectors, as well as those with an interest in physics. It works to advance physics research, application and education; and engages with policy makers and the public to develop awareness and understanding of physics. Its publishing company, IOP Publishing, is a world leader in professional scientific communications. Go to http://www.iop.org
The German Physical Society
7. The German Physical Society (DPG) with a tradition extending back to 1845 is the largest physical society in the world with more than 59,000 members. The DPG sees itself as the forum and mouthpiece for physics and is a non-profit organisation that does not pursue financial interests. It supports the sharing of ideas and thoughts within the scientific community, fosters physics teaching and would also like to open a window to physics for all those with a healthy curiosity.
AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.