Network elements and sub-systems for OTDM optical networks

  • Buxens Azcoaga, Alvaro Juan, (Project Manager)
  • Clausen, Anders (Project Participant)
  • Poulsen, Henrik Nørskov, (Project Participant)
  • Yu, Jianjun, (Project Participant)


Optical Time Division Multiplexing(OTDM) allows to increase the bit rate of a single wavelength channel by means of interleaving in time optical modulated signals. A necessary component when doing research in OTDM is the multiplexer, which allows to obtain a high bit rate signal (e.g. 40 Gbit/s) from an initial base rate signal (e. g. 10 Gbit/s). Usually fiber based devices are used in our laboratories, being bulky and not ideal. In a M.Sc. project a multiplexer based on planar technology was implemented, tested and used in transmission experiments.
Another basic component needed in OTDM technology is the demultiplexer, which allows to obtain the basic bit rate signal (10 Gbit/s) from the high bit rate signal (40 Gbit/s). Following the relation initiated within the European ACTS project HIGHWAY we cooperated intensively on this research topic with the Institute for Quantum Electronics at the Swiss Federal Institute of Technology in Zurich. We achieved demultiplexing of a 10 Gbit/s channel from a 160 Gbit/s signal (16 channels at 10 Gbit/s) using a fully packaged Mach-Zehnder interferometric SOA based device. An additional functionality that can be obtained from such a device is the ability to substitute the demultiplexed channel with a new one (add-drop multiplexing). We have investigated new methods of add-drop multiplexing which allow for simultaneous regeneration of the original signal. These methods will make possible long distance transmission of signals in an all optical network without deterioration.
We have continued the investigation of the applications of bi-directional four wave mixing in SOAs and proposed methods to avoid the inherit polarisation dependence of four wave mixing and to allow for add-drop multiplexing in OTDM systems. The proposed technique to avoid the four wave mixing polarisation dependence was applied in a 100 km transmission experiment for return to zero signals using four wave mixing as the active dispersion compensation technique.
Effective start/end date01/01/199931/12/2002