Monte Carlo simulations of pulse propagation in massive multichannel optical fiber communication systems

We study the combined effect of delayed Raman response and bit pattern randomness on pulse propagation in massive multichannel optical fiber communication systems. The propagation is described by a perturbed stochastic nonlinear Schr\"odinger equation, which takes into account changes in pulse amplitude and frequency as well as emission of continuous radiation. We perform extensive numerical simulations with the model, and analyze the dynamics of the frequency moments, the bit-error-rate, and the mutual distribution of amplitude and position. The results of our numerical simulations are in good agreement with theoretical predictions based on the adiabatic perturbation approach.Comment: Submitted to Physical Review E. 8 pages, 5 figure

Evaluation of Non-Linear Interference in Uncompensated Links using Raman Amplification

We extend a model for nonlinear propagation over lumped-amplified uncompensated links to setups using Raman amplification. We compare theoretical to simulative results for PM-16QAM Nyquist-WDM on PSCF links, showing an excellent agreement. We also show that Raman NLI enhancement gives limited practical impairments in realistic setup

The GN-Model of Fiber Non-Linear Propagation and its Applications

Several approximate non-linear fiber propagation models have been proposed over the years. Recent reconsideration and extension of earlier modeling efforts has led to the formalization of the so-called Gaussian-noise (GN) model. The evidence collected so far hints at the GN-model as being a relatively simple and, at the same time, sufficiently reliable tool for performance prediction of uncompensated coherent systems, characterized by a favorable accuracy versus complexity trade-off. This paper tries to gather the recent results regarding the GN-model definition, understanding, relations versus other models, validation, limitations, closed form solutions, approximations and, in general, its applications and implications in link analysis and optimization, also within a network environmen

16x125 Gb/s Quasi-Nyquist DAC-Generated PM-16QAM Transmission Over 3590 km of PSCF

We report on a transmission experiment over high-performance pure silica core fiber (PSCF) of 16 Nyquist wavelength-division-multiplexed (Nyquist-WDM) channels at a symbol rate of 15.625 GBaud, using polarization-multiplexed (PM) 16 symbols quadrature amplitude modulation (16QAM), resulting in a per-channel raw bit rate of 125 Gb/s. The channel spacing is 16 GHz, corresponding to 1.024 times the symbol rate. The interchannel crosstalk penalty is drastically reduced through the confinement of the signal spectrum within a near-Nyquist bandwidth, achieved with digital filtering and digital-to-analog converters (DACs) operating at 1.5 samples/symbol. The optical line is a recirculating loop composed of two spans of high-performance PSCF with erbium-doped fiber amplifiers only. The transmission distance of 3590 km at a target line bit-error rate (BER) of 1.5 10^-2 is achieved at a raw spectral efficiency (SE) of 7.81 b/s/Hz. Assuming a commercial hard forward error correction with 20.5% redundancy, capable of handling the target BER, the net SE is 6.48 b/s/Hz, the highest so far reported for multithousand kilometer transmission of PM-16QAM at ≥ 100 Gb/s per channel. These results demonstrate the feasibility of very high SE DAC-enabled ultra-long-haul quasi-Nyquist-WDM transmission using PM-16QAM with current technologies and manageable digital signal processing complexit

Design rules for reach maximization in uncompensated Nyquist-WDM links

We propose analytical design rules to predict relative maximum reach variations in NyWDM uncompensated links. Tradeoffs among system parameters are shown. Validation is demonstrated using experimental data. The method can be used also for comparison of different modulation format

Intermittent dynamics, strong correlations, and bit-error-rate in multichannel optical fiber communication systems

We investigate the effects of delayed Raman response on pulse dynamics in massive multichannel optical fiber communication systems. Taking into account the stochastic nature of pulse sequences in different frequency channels and the Raman induced energy exchange in pulse collisions we show that the pulse parameters exhibit intermittent dynamic behavior, and that the pulse amplitudes exhibit relatively strong and long-range correlations. Moreover, we find that the Raman-induced cross frequency shift is the main intermittency-related mechanism leading to bit pattern deterioration and evaluate the bit-error-rate of the system.Comment: 17 pages, 4 figures. Submitted to Phys. Lett.

Experimental Investigation of Nonlinear Interference Accumulation in Uncompensated Links

Noise due to nonlinear effects in uncompensated links has recently been shown to be Gaussian and additive. We experimentally investigate the law governing its accumulation. Our results suggest a mild super-linear accumulation versus number of spans, compatible with coherent accumulation model

Investigation of the Dependence of Non-Linear Interference on the Number of WDM Channels in Coherent Optical Networks

We experimentally investigate nonlinearity impact in a multi-span uncompensated coherent optical system, transmitting, in the 50GHz grid, Nchx100G CP-DQPSK channels, varying Nch from 3 to 71. A good agreement was found with an analytical model, confirming the progressive growth of interference with Nch. Impacts on network design are evaluate

Compatibility between coherent reflective burst-mode PON and TWDM-PON physical layers

We discuss the compatibility between reflective PON architectures and the recently defined ITU-T G.989.1 TWDM-PON. Focusing on the upstream, we experimentally demonstrate that, by using burst-mode coherent detection at OLT, reflective PON can achieve the specification target set for TWDM-PON, without requiring precise wavelength accuracy at ONU. Compared to the companion ECOC 2013 paper, we investigate on the differential optical path loss (DOPL) issue, proposing a simple SOA gain control algorithm to achieve reliable transmission for DOPL up to 17 d