The new system works by controlling waves called surface plasmons. These waves are oscillations of electrons confined at interfaces between materials; in the new system the waves operate at terahertz frequencies. Such frequencies lie between those of far-infrared light and microwave radio transmissions, and are considered ideal for next-generation computing devices.
The findings were reported in a paper inApplied Physics Lettersby associate professor of mechanical engineering Nicholas Fang, postdoc Dafei Jin and three others.
The system would provide a new way to construct interconnected devices that use light waves, such as fiber-optic cables and photonic chips, with electronic wires and devices. Currently, such interconnection points often form a bottleneck that slows the transfer of data and adds to the number of components needed.
The team's new system allows waves to be concentrated at much smaller length scales, which could lead to a tenfold gain in the density of components that could be placed in a given area of a chip, Fang says.
The team's initial proof-of-concept device uses a small piece of graphene sandwiched between two layers of the ferroelectric material to make simple, switchable plasmonic waveguides. This work used lithium niobate, but many other such materials could be used, the researchers said.
Light can be confined in these waveguides down to one part in a few hundreds of the free-space wavelength, Dafei Jin said, which represents an order-of-magnitude improvement over any comparable waveguide system. "This opens up exciting areas for transmitting and processing optical signals", he stated.
Moreover, the work may provide a new way to read and write electronic data into ferro-electric memory devices at very high speed, the MIT researchers said.
In addition to Nicholas Fang and Dafei Jin, the research was carried out by graduate student Anshuman Kumar, former postdoc Kin Hung Fung - now at Hong Kong Polytechnic University, and research scientist Jun Xu.
The research was supported by the National Science Foundation and the Air Force Office of Scientific Research.