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December 04, 2008

Loss of Light Prevented in Metamaterials

Researchers have solved one of the significant remaining challenges with photonic “metamaterials,” discovering a way to prevent the loss of light as it passes through these materials, and opening the door to many important new optical, electronic and communication technologies.

Photonic metamaterials are engineered composite materials with unique electromagnetic properties, and have attracted significant research interest in recent years due to their potential to create “negative index” materials that bend light the opposite way of anything found in the natural world. But their performance has been significantly limited by the absorption of light by metals that are part of their composition – metal might absorb much more than 50 percent of the light shined on it, and drastically reduce the performance of devices based on these materials.

The solution to this problem, researchers discovered, is to offset this lost light by adding an optical “gain” to a dielectric adjacent to the metal. The new publication outlines how to successfully do that, and demonstrates the ability to completely compensate for lost light. It had been theorized that this might be possible, the researchers said, but it had never before been done, and the theories themselves were the subject of much scientific debate.

As such, this may have removed a final roadblock and now made possible “a number of dreamed about applications.


Stimulated Emission of Surface Plasmon Polaritons





We have observed laserlike emission of surface plasmon polaritons (SPPs) decoupled to the glass prism in an attenuated total reflection setup. SPPs were excited by optically pumped molecules in a polymeric film deposited on the top of a silver film. Stimulated emission was characterized by a distinct threshold in the input-output dependence and narrowing of the emission spectrum. The observed stimulated emission and corresponding compensation of the metallic absorption loss by gain enables many applications of metamaterials and nanoplasmonic devices.

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