We investigate the nonlinear tolerance of coherent detected 50 Gbit/s dual-polarization binary-phase-shift-keying (DPBPSK),
100 Gbit/s dual-polarization quaternary-phase-shift-keying (DP-QPSK), and 200 Gbit/s dual-polarization 16-ary
quadrature amplitude modulation (DP-16-QAM) for single carrier with pulse shaping and orthogonal frequency division
multiplexing (OFDM). The performance of these systems is compared and tested in two different scenarios: dispersion
managed and unmanaged links. The results show that employing return-to-zero with 50 % of duty cycle (RZ50) as pulse
shaping has a superior performance, especially in dispersion unmanaged links.
We investigate the interaction between linear and nonlinear compensation within back-propagation algorithm applied to
next-generation 400-Gbps systems. A significant performance improvement is reported by taking into account the
interaction of these two parts.
Presently, formerly independent autonomous optical links are growing increasingly into meshed networks making measures for performance monitoring and automated error analysis a necessity. At the same time adaptive electronic equalizers are becoming integrated by default into optical receivers in order to mitigate distortions which are ubiquitous on every fiber link. In this paper we investigate the possibility of using these already available components for identifying and quantifying optical distortions and thus, performing network monitoring without additional expensive optical equipment.
Currently existing dense wavelength division multiplexing (DWDM) networks start to migrate from numerous point-to-point links towards meshed, transparent, optical networks with dynamically routed light paths. This increases the need for appropriate network monitoring and supervision methods. Optical performance monitoring (OPM) has to be cost-effective. Thus additional spendings for OPM have to be significantly smaller than the savings in OPEX due to increased reliability and ease of operation, administration, and maintenance (OAM). We elaborate on different advanced monitoring concepts. First, we discuss general failure scenarios in meshed networks. Then we describe software based failure root cause analysis and its implementation. We conclude that by implementing appropriate software algorithms in the network hardware effort can be significantly reduced. Finally, we assess different advanced OPM methods which may show up as useful to enable OPM in future optical networks.