While scientists have known since the 1990s that electromagnetic waves could be trapped and used for important applications like information storage and quantum optics, the complexity of the experimental setup and the inability to develop a method for releasing the waves in their original state has stalled significant research and development for almost two decades.
Traditional methods of trapping electromagnetic waves rely on clouds of atoms with the ability to absorb or allow waves to pass through depending on their frequency. By stimulating the atoms with a laser and temporarily changing the frequency of the atoms, scientists are able to control the capture and release of the electromagnetic waves, but are unable to release the waves with their original properties intact.
Now, researchers at Kyoto University in Japan have discovered a method for capturing and holding electromagnetic waves inside of a metamaterial and then releasing them in the same state. Toshihiro Nakanishi and his colleagues have created a metamateral—an artificial material imbued with properties that may not be found in nature—containing two variable capacitors in each repeating unit, one designed to absorb and radiate waves at a particular frequency and another designed to trap waves. By tuning both capacitors to the same frequency, any electromagnetic waves at that frequency are absorbed and trapped. Changing the frequency of the capacitors released the waves with “the same phase distribution as the originals,” according to the researchers.
Though the technique used a metamaterial made of only three layers and is currently only successful at trapping and releasing microwaves, Nakanishi and his colleagues believe that additional research could yield results with thicker metamaterials and waves of other frequencies.
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