WAVELENGTH CONVERSION TECHNOLOGIES FOR WDM NETWORK APPLICATIONS

WDM networks make a very effective utilization of the fiber bandwidth and offer flexible interconnections based on wavelength routing, In hi gh capacity, dynamic WDM networks, blocking due to wavelength contenti on can be reduced by wavelength conversion, Wavelength conversion addr esses a number of key issues in WDM networks including transparency, i nteroperability, and network capacity, Strictly transparent networks o ffer seamless interconnections with full reconfigurability and interop erability. Wavelength conversion may be the first obstacle in realizin g a transparent WDM network, Among numerous wavelength conversion tech niques reported to date, only a few techniques offer strict transparen cy, Optoelectronic conversion (O/E-E/O) techniques achieve limited tra nsparency, yet their mature technologies allow deployment in the near future, The majority of all-optical wavelength conversion techniques a lso offer limited transparency but they have a potential advantage ove r the optoelectronic counterpart in realizing lower packaging costs an d crosstalk when multiple wavelength array configurations are consider ed, Wavelength conversion by difference-frequency generation offers a full range of transparency while adding no excess noise to the signal, Recent experiments showed promising results including a spectral inve rsion and a 90 nm conversion bandwidth, This paper reviews various wav elength conversion techniques, discusses the advantages and shortcomin gs of each technique, and addresses their implications for transparent networks.