One Directional Metamaterial to Enable OptoelectronicsCategory: Science & Technology
Posted: August 16, 2012 01:58PM
Everyone is familiar with how easily light is reflected, especially as most of the light we see is reflected off of surfaces. Unfortunately the ease with which light is reflected is a problem for optoelectronics because light traveling in the wrong direction can interfere with signals and disrupt the laser source. To combat this, devices use what is called an isolator, but this component is complex and impairs the optical signal it is trying to protect. Researchers at MIT however have developed a metamaterial that forces light to go in one direction.
Isolators are made of a material that will absorb photons when exposed to a magnetic field. This prevents photons from traveling the wrong direction by simply catching and absorbing them, but it also weakens the signal moving in the correct direction. Such weakening makes it difficult to connect multiple optical devices together, as signals cannot reach as far. The metamaterial however does not absorb photons but just redirects them. This actually has the effect of strengthening the signal as any photons that would otherwise escape the signal are brought back in line with the others.
This new metamaterial introduces some problems of its own, unfortunately. Though the researchers are confident they can scale the design down to operate in chips and manufactured with modern technology, the high-frequency transistors needed to operate at visible wavelengths do not exist. However, it may be possible to use nonlinear materials to work around this; a possibility the researchers are still working on.