Design and optimization of multi-haul DWDM networks

Abstract

There is an increasing demand for DWDM systems to support a set of network requirements (span length, total distance, capacity, etc) typically associated with previously distinct network application categories such as access, metro, regional, and long haul. This has led to the development of a multi-haul DWDM system, defined as an agile optical platform, able to combine multiple versions of transponders, amplifiers, and optical add/drop multiplexers (OADM) on the same optical link. The concept of a multi-haul system is applied in a study of DWDM networks that can employ, besides fixed OADM, two types of reconfigurable OADM (ROADM): a two-degree ROADM based on arrayed-waveguide gratings (AWG) and a multi-degree ROADM built with 5x1 wavelength-selective switches (WSS). A cost analysis on a network example calculates the savings obtained if an optimum mix of ROADMs is used on the same DWDM ring instead of deploying one single OADM type at all nodes. A technical feasibility study is performed to validate the performance of a DWDM system with up to 16 ROADMs in a network. To this purpose, OSNR penalties are experimentally determined for AWG and WSS ROADMs due to cascaded bandwidth narrowing, and crosstalk effects, with wavelength detuning values corresponding to locked and unlocked lasers.