Emerging Technology from the arXiv

A View from Emerging Technology from the arXiv

Carpet Cloaks Bring Invisibility to the Optical World

Carpet cloaks make practical cloaking at visible wavelengths possible for the first time.

  • April 29, 2009

It wasn’t long ago that some physicists said that optical invisibility cloaks would be impossible to build. This week, two teams are claiming to have built cloaks that work over a wide range of optical wavelengths, and the extraordinary thing is that both designs are almost identical (see above).

Invisibility cloaks work by steering light around an object, fooling an observer who sees nothing but the background view. But while this works well for microwaves, it is not a straightforward matter to shrink these cloaks to a size that works at optical wavelengths.

Now Michal Lipson and pals at Cornell University, and Xiang Zhang and buddies at UC Berkeley, say that they have both built cloaks that are essentially mirrors with a tiny bump in which an object can hide. The cloaking occurs because the mirrors look entirely flat. The bump is hidden by a pattern of tiny silicon nanopillars on the mirror surface that steers reflected light in a way that makes any bump look flat. So anything can be hidden beneath the bump without an observer realizing that it is there, like hiding a small object under a thick carpet.

You may wonder at the timing: how can two teams come up with the same design at almost exactly the same time?

The answer is that both designs are based on an idea dreamed up by John Pendry at Imperial College, London, and a colleague, which we examined on the arXiv blog last July. It’s just taken both groups the same amount of time to build one.

Ref:

arxiv.org/abs/0904.3508: Cloaking at Optical Frequencies

arxiv.org/abs/0904.3602: Dielectric Optical Cloak

Become an MIT Technology Review Insider for in-depth analysis and unparalleled perspective.
Subscribe today

Uh oh–you've read all five of your free articles for this month.

Insider Premium

$179.95/yr US PRICE

Want more award-winning journalism? Subscribe and become an Insider.

  • Insider Premium {! insider.prices.premium !}*

    {! insider.display.menuOptionsLabel !}

    Our award winning magazine, unlimited access to our story archive, special discounts to MIT Technology Review Events, and exclusive content.

    See details+

    What's Included

    Bimonthly home delivery and unlimited 24/7 access to MIT Technology Review’s website.

    The Download. Our daily newsletter of what's important in technology and innovation.

    Access to the Magazine archive. Over 24,000 articles going back to 1899 at your fingertips.

    Special Discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

    First Look. Exclusive early access to stories.

    Insider Conversations. Join in and ask questions as our editors talk to innovators from around the world.

  • Insider Plus {! insider.prices.plus !}* Best Value

    {! insider.display.menuOptionsLabel !}

    Everything included in Insider Basic, plus ad-free web experience, select discounts to partner offerings and MIT Technology Review events

    See details+

    What's Included

    Bimonthly home delivery and unlimited 24/7 access to MIT Technology Review’s website.

    The Download. Our daily newsletter of what's important in technology and innovation.

    Access to the Magazine archive. Over 24,000 articles going back to 1899 at your fingertips.

    Special Discounts to select partner offerings

    Discount to MIT Technology Review events

    Ad-free web experience

  • Insider Basic {! insider.prices.basic !}*

    {! insider.display.menuOptionsLabel !}

    Six issues of our award winning magazine and daily delivery of The Download, our newsletter of what’s important in technology and innovation.

    See details+

    What's Included

    Bimonthly home delivery and unlimited 24/7 access to MIT Technology Review’s website.

    The Download. Our daily newsletter of what's important in technology and innovation.

You've read of free articles this month.