Wavelength Division Multiplexed Add/Drop Ring Technology in Corporate Backbone Networks

The Corporate Optical Backbone Network (COBNET) project is a joint research project within the ACTS program of the European Commission. The COBNET consortium is considering the use of advanced optical networking technologies for the backbones of future corporate networks. In particular, multichannel add/drop ring networks based on wavelength division multiplexing (WDM) as well as on optical space-division multiplexing (SDM) technologies are being pursued. In the first part of the paper, an overview is given of the system concept, the device technology, and the demonstration network that have been developed within COBNET. The second part of the paper focuses in more detail on the WDM ring option and specifically on the related add/drop devices. They are fabricated in a newly developed high-refractive-index contrast planar silica-on-silicon technology by using silicon-oxynitride (SiON) as the core waveguide material. Compact add/drop components based on the resonant coupler concept are realized. The filter characteristic can be tailored and tuned by thermo-optic heaters, which allows the selection of any given wavelength out of a series of wavelengths from the WDM ring using one and the same device.