Technologies and Applications for Space-Switching in Multi-Wavelength Networks

Optical routing may adequately complement electrical switching in future, high-capacity telecommunications networks [l]-[3]. For instance, photonic space division switches are suitable for routing of large volume aggregate information streams involving switching on a relatively slow time scale; this property can be useful in applications such as protection routing or protection switching and also in establishing semi-permanent connections in the network, whereas electronic systems are superior for fast time switching or individual processing of time multiplexed data streams. A simple, rearrangeable optical layer may support one wavelength, but a more complex layer capable of handling several different optical carriers individually would allow an increased switching granularity and would also make better use of the potential capacity of an optical network layer. A rearrangeable optical network layer supporting wavelength division multiplexing (WDM) would thus enable a network for which the excellent transmission properties of the optical fibre could—to a certain extent—be retained, the requirements on electrical cross-connect systems be relaxed, and the capacity and operational flexibility of the network be enhanced. Construction of this type of optical networks requires high-quality photonic devices, including wavelength-tunable laser transmitters, wavelength-tunable optical filters, optical amplifiers, optical space division switches, and, to enhance network performance, optical wavelength converters. In addition, systems for management and control suitable for such optical layers are needed [l]-[3].