1. Networking and Transmission Laboratory, Acreo AB, Electrum 236, SE-164 40, Kista, Sweden
2. Fraunhofer Institute for Telecommunications, HHI, Einsteinufer 37, 10587 Berlin, Germany
3. Nokia Siemens Networks GmbH & Co. KG, D-80240 Munich, Germany
4. Fraunhofer Institute for Applied Solid State Physics, Tullastr. 72, 79108 Freiburg, Germany
5. Royal Institute of Technology, Electrum 229, SE-164 40, Kista, Sweden
6. u2t Photonics AG, Reuchlinstrasse 10/11, 10553 Berlin, Germany