A collaboration of researchers from Moscow State University, Sandia National Laboratories, and Friedrich-Schiller University have fabricated an ultrafast metamaterial whose properties can be tuned using ultrashort laser pulses. The work, published in Nature Communications, could lead to the ultrafast transfer of data on the nanoscale.
The new metamaterial can be tuned using ultrashort laser pulses. (Credit: Maxim Shcherbakov)
Metamaterials are man-made media that acquire unusual optical properties as a result of nanostructuring. Scientists have been using metamaterials for almost 20 years to design a variety of devices, such as those that can hide objects, or those that are sensitive to minute concentrations of substances. While conventional metamaterial properties remain fixed, the collaboration’s new material can have its properties turned ‘on’ and ‘off,’ rapidly.
The new metamaterial was fabricated using a thin film of gallium arsenide, electron-beam lithography and plasma etching. It consists of an array of semiconductor nanoparticles, which can resonantly concentrate and ‘hold’ light on the nanoscale. In other words, when light illuminates the metamaterial, it is ‘trapped’ inside the nanoparticles and interacts more efficiently with them.
The researchers can activate the new metamaterial by illuminating it with an ultrashort laser pulse, which generates both electrons and electron holes in the material. The presence of the electrons and holes changes the properties of the material rapidly from being reflective to non-reflective. Once the electrons and holes disappear after coming into contact with each other, the metamaterial properties return to being reflective. By using ultrashort laser pulses this way, the researchers are able to change the reflective properties of the material more than 100 billion times a second.
In 2015, the collaboration produced a similar device based on silicon nanostructures rather than gallium arsenide. The recent change in structure has increased the efficiency of controlling light via light in metamaterials by a whole order of magnitude.
Prospectively, the new material will enable optical logic elements to be produced, along with the creation of devices that can transfer data at speeds of hundreds of terabits per second, which could in turn lead to the development ultrafast optical computers in the future.