Scaling 100G QPSK links for Reliable Network Development

摘要

Nonlinearities are a performance limitation in coherent optical links, and efforts have been made to understand the tradeoffs between launch power and the penalties related to nonlinearities. Using both simulation and experimental results from our 100G testbed we investigate the use of a nonlinear phase criterion that quantifies the total nonlinear phase accumulation within a 112 Gb/s PDM-QPSK link. We examine the nonlinear effects of self-phase (SPM) and cross-phase modulation (XPM) on a 112 Gb/s PM-QPSK channel propagating between four 10 Gb/s OOK aggressor channels on a 50 GHz grid and quantify the launch power and span count scaling behavior. In order to assess the applicability of a nonlinear phase criterion on real-world links, we determine the launch power that yields a 1.5 dB OSNR penalty at a BER of 10"3 for each configuration. This launch power then allows the identification of a Nonlinear Threshold Power (number of spans times launch power) that fully incorporates the increasing nonlinear penalties with further transmission distance. This metric allows for the determination of a set of engineering rules for deployment of 100 Gb/s PDM-QPSK in linear links with arbitrary number of spans and span distances. We find that this nonlinear threshold decreases in dispersion-compensated links. These experimental results are validated with simulations.