Selective Transparency in Optical Networks

Core optical networks can benefit from lower costs and increased speed by reducing O-E-O conversions through use of ultra long reach optical transport, and bit-rate and wavelength transparent cross-connects. While pure optical transparency avoids the high cost of deploying optical termination units (OTUs) for each wavelength channel, it incurs new costs with additional fiber requirements and reduced provisioning capability. This paper describes an intermediate option, selective transparency that uses small pools of wavelength converters at cross-connect nodes, which combines the advantages of reduced OTU count, minimal additional fiber, and high reconfigurability to support changing traffic patterns