Ultra high speed OTDM over standard fibre

Optical time division multiplexing (OTDM) is an attractive alternative to wavelength division multiplexing for future high capacity all optical networks. In order to provide a low cost evolution strategy to upgrade a network, it is imperative that any techniques exploit existing fibre plant. Several techniques have been proposed to overcome the chromatic dispersion inherent in installed fibre. We report two studies of dispersion compensation as an enabling technology for 40 Gbit/s OTDM system and network applications on standard fibre. In addition to removing the need for dispersion shifted fibre at 1.5 mu m, the techniques adopted have been chosen to maximise the repeater spacing above those currently installed in transmission networks. Specifically the reported distance bit rate products of 3.2 Tbit/s.km unrepeatered and 8.1 Tbit/s.km with a single repeater represent world record performance for single channel systems. The first technique, optical dispersion compensation (using dispersion compensating fibre), has recently attracted significant interest by virtue of its straight-forward approach to the fundamental problem. That is, the link dispersion is directly negated by a length of fibre of almost exactly opposite total dispersion. Results are presented for an 80 km unrepeatered link. The second technique, mid span spectral inversion, requires little in the way of additional optics in the signal path, and certainly no modifications to standard terminal equipment.<>