Engineers at Georgia Institute of Technology have demonstrated the first optical rectenna, which combines an antenna and a rectifier diode to convert light into DC current. The device uses carbon nanotubes that act as antennas to capture light from the sun or other sources, creating an oscillating charge. As the charge moves through the attached rectifier devices, the rectifiers switch on and off and create a small direct current.
Advances in fabrication technology have made it possible to capture solar energy in this way. While rectennas have operated at wavelengths as short as ten microns for more than 40 years, this optical rectenna is the first of its kind.
Currently, its efficiency is below one percent, but the researchers predict a greater than 40 percent efficiency in the near future, with commercial potential available within a year.