Technologies for optical networking in Nx160-Gbit/s DWDM networks

Abstract

Future multi-terabit/s optical core networks require optical technologies capable of managing ultra-high bit rate OTDM/DWDM (optical time division multiplexing/dense wavelength division multiplexing) channels at 160 Gbit/s or higher bit rates. The key functionalities in ultra-high speed network nodes are all-optical wavelength conversion, 3R-regeneration and demultiplexing of OTDM signals. Advanced optical networking techniques (optical add-drop multiplexing and optical routing) are studied in simulations and their performance evaluated considering 160 Gbit/s OTDM/DWDM channels. Performance comparison results for both OADM (optical add-drop multiplexer) and OXC (optical cross-connect) node networking functionalities are shown considering different technologies: semiconductor-optical-amplifier-based symmetric Mach-Zehnder interferometers (SOA-MZI) for wavelength conversion, signal regeneration and demultiplexing, electroabsorption-modulator-based demultiplexers, and wavelength converters based on four-wave mixing in dispersion-shifted fiber. The simulation results show that the SOA-MZI is a promising technology for all-optical signal processing in network nodes mainly due to its signal regeneration capability. At ultra-high bit rates, however, the relaxation time of SOAs considerably limits the operation. A solution to mitigate this problem is to use a differential scheme at the input of the device. Error-free wavelength conversion, signal regeneration and demultiplexing of 160 Gbit/s OTDM signals employing a SOA-MZI with a differential scheme is demonstrated by means of simulations. Furthermore, the parameters of this architecture are optimized to obtain the best performance for each optical networking functionality in OADM and OXC network nodes.