Fraunhofer HHI demonstrates eye-safe optical link over 380 meters

In November 2016, the Fraunhofer Heinrich-Hertz-Institut in Berlin demonstrated an eye-safe optical data transmission over a distance of 380 m at a speed of 1,7 Terabit/s.

There are several ways to transfer large amounts of data from one location to another. One of them is the fast optical free-space communication, which uses light as a carrier of information. The group "Free-Space Optical Systems" around Nicolas Perlot at the Fraunhofer HHI is concerned with this area. The laser-based Fraunhofer HHI systems cover applications in both terrestrial networks and satellite communications. The connections are eye-safe, tap-proof and do not require a frequency license.

For the demonstration of the optical link communication of 2x1,7-Tbit/s over a distance of 380 m, both bidirectional terminals were placed in the same building. A relay mirror was placed in the other building to increase the transmission distance. The signals consisted of 40 wavelength channels with a data rate of 43 Gbit/s each in both directions. Fine and coarse tracking systems stabilized the coupling into the single-mode fibers at both terminals. Eye-safe operation through 380 m air was successfully demonstrated at a total antenna output power of less than 10 mW. 

With this experiment, the scientists at Fraunhofer HHI have successfully demonstrated that optical wireless data transmission is possible in the terabit range. The team is now conducting further research to increase the transmission distance to several kilometres and compensate for turbulence effects.

Within the framework of the experiments, a fibre-optic transmission system of the Fraunhofer Heinrich-Hertz-Institut was employed which operates at wavelengths of around 1550 nanometres and which is suitable for high data rates. This system was integrated into DLR's (German Aerospace Center) newly developed free-space optic transmission system, where Fraunhofer HHI supported the on-site tests.