Standard TV-antennas receive signals carried by electromagnetic waves with frequencies in the MHz-regime and convert them into pulses of electric currents in the connected cables. The antenna connects two very different length scales: the carrier wavelength, ranging from centimeters to meters, and the size of the wiring, typically on the millimeter scale. Now, physicists at the 4 th Physics Institute of the University of Stuttgart in collaboration with researchers at the Max-Planck-Institute for Solid State Research successfully applied this radiofrequency antenna concept to the optical wavelength regime. They realized metallic structures of only 100 nanometer size, which efficiently receive optical frequencies in the range of several hundreds of THz. This opens up new possibilities to speed up optical data transfer. The results have been reported on Apr. 5, 2011, in the scientific journal Nature Communications.*)
Certain antenna geometries are known to receive radiation from designated directions. Such a unidirectional TV-antenna is the so-called Yagi-Uda-antenna, invented by Yagi and Uda in 1926. Consisting of several aligned parallel dipole antennas of different lengths, the Yagi-Uda-antenna can be tuned to receive signals from a given direction 5 to 10 times more efficiently than a dipole antenna. The received signal can be even more enhanced by several orders of magnitude when the single antenna is expanded to an array of Yagi-Uda antennas. Such antenna arrays are used to transmit signals over very large distances, for example in satellite communication.
Prof. Harald Giessen, 4th Physics Institute, University of Stuttgart, phone 0711/685-65111,
e-mail giessen@physik.uni-stuttgart.de or
Dipl.-Phys. Daniel Dregely, 4th Physics Institute, University of Stuttgart, phone 0711/685-64961,
e-mail d.dregely@physik.uni-stuttgart.de