Impact of signal-ASE four-wave mixing on the effectiveness of digital back-propagation in 112 Gb/s PM-QPSK systems

Abstract

Limitations in the performance of coherent transmission systems employing digital back-propagation due to four-wave mixing impairments are reported for the first time. A significant performance constraint is identified, originating from four-wave mixing between signals and amplified spontaneous emission noise which induces a linear increase in the standard deviation of the received field with signal power, and linear dependence on transmission distance.

On the performance of multichannel digital backpropagation in high-capacity long-haul optical transmission

“…It should be noted that, as expected, system performance improved with increased backpropagated bandwidth (in Q 2 ), with slight saturation as we approach the full-field DBP bandwidth (0.83 dB per backpropagated channel between 0 and 3 channels and 0.65 dB per backpropagated channel between 3 and 5 channels). The reason for this saturation is twofold: (i) the nonlinearity scaling logarithmically with the bandwidth [26] and (ii) the predominance in the effective SNR of the ASE-signal nonlinear interaction when the DBP bandwidth is close to the one of the entire field [10].…”

“…A number of groups have already investigated in simulations the achievable improvements with multichannel DBP when the entire signal field is backpropagated [9][10][11][12][13][14]. Significant improvements in both Q 2 factor and reach have been achieved for PDM-16QAM modulation format compared to single channel DBP.…”

Optical and Digital Phase Conjugation Techniques for Fiber Nonlinearity Compensation

“…1(b)), on the other hand, is an all optical technique which provides compensation of both intra and inter channel nonlinear effect if the power profile along the link is symmetrical and third order dispersion is ignored. In this case, the system performance is limited by parametric noise amplification [11]. Assuming ideal compensation of inter and intra signal nonlinearities, the compensated SNR in system with ideal OPC/DBP can be estimated as:…”

Digital Backward Propagation: A Technique to Compensate Fiber Dispersion and Non-Linear Impairments

“…The second observation in this article is about the oversampling rate which improves system performance by DBP. A number of investigations with diverse transmission configurations have been done with coherent detection and split-step Fourier method (SSFM) Mateo et al, 2011;Millar et al, 2010;Mussolin et al, 2010;Rafique et al, 2011a;Yaman et al, 2009). The results in these articles shows efficient mitigation of CD and NL.…”