Invisibility Cloaks Trap a Rainbow


A group of American researchers has created an array of 25,000 invisibility cloaks measuring 30 micrometers in diameter. This array is the first of its kind.

It was created by researchers from Towson University and the University of Maryland. The research has just been published in the Institute of Physics and German Physical Society’s New Journal of Physics.

This new array of invisibility cloaks can be used to slow down and even stop light, creating what is called a “trapped rainbow.”

This “trapped rainbow” can be used in tiny biosensors used to identify biological material based on the amount of light they absorb and then re-emit, which is known as fluorescence spectroscopy. When light is slowed down it has a stronger interaction with molecules, allowing better analysis.

20120525-115928.jpg Lead author of the study, Dr Vera Smolyaninova, said: “The benefit of a biochip array is that you have a large number of small sensors, meaning you can perform many tests at once. For example, you could test for multiple genetic conditions in a person’s DNA in just one go.”

“In our array, light is stopped at the boundary of each of the cloaks, meaning we observe the trapped rainbow at the edge of each cloak. This means we could do ‘spectroscopy on-a-chip’ and examine fluorescence at thousands of points all in one go.”

The 25,000 invisibility cloaks are uniformly spread out on a gold sheet, each one having a microlens that bends light around itself, hiding an area in its middle. When the light squeezes through the gaps located between the cloaks, the different components of light are made to stop at ever narrower points, creating the rainbow.

To construct the array of invisibility cloaks, the researchers used a commercially available microlens display, which was then coated with a gold film, and this was placed gold-side down onto a glass side that was also coated with gold, creating a double layer. A laser was then directed into the display to test its performance at different angles.

The researchers think that this type of array can be used to test individual invisibility cloaks, especially in instances where the cloaks are placed close together. For example, in this display the array worked very well when light was shined along the rows, but at other angles imperfections were clear.

Source: Institute of Physics
Image Credits: Triangle Rainbow and Light via Shutterstock

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