All-Optical Nonlinear Pre-Compensation of Long-Reach Unrepeatered Systems

Abstract

We numerically demonstrate an all-optical nonlinearity pre-compensation module for state-ofthe-art long-reach Raman-amplified unrepeatered links. The compensator design is optimized in terms of propagation symmetry to maximize the performance gains under WDM transmission, achieving 4.0dB and 2.6dB of SNR improvement for 250-km and 350-km links.

Lumped Compensation of Nonlinearities based on Optical Phase Conjugation

“…17 allows additional freedom in designing the system. As shown in [25], [32]- [34] and further discussed in the following sections, fibers with opposite signs of dispersion can be considered for the links before and after the OPC. Such links are not fulfilling the condition provided by Eq.…”

“…Moreover, it is noted that the system in Fig. 2 employs fibers with opposite dispersion signs on each side of the OPC, as discussed in [25], [32]- [34]. This allows for the OPC symmetry to be achieved using simple lumped amplification -by e.g.…”

“…The degree of symmetry, however, varies depending on the considered system scenario. Due to exponential power decay in both spans, matching the slopes in NADD requires that the link and the compensation fiber have opposite dispersion signs [25], [32]- [34], which is the case for System2 and System3, though not for System1. Despite this limitation, and even though the OBP addresses only a small fraction of the link due to low β, substantial gains are still demonstrated for all three cases, as illustrated in Fig.…”

Symmetry Enhancement Through Advanced Dispersion Mapping in OPC-Aided Transmission

“…As the fiber parameters are fixed, it might not be possible to consistently restore the correct nonlinearity across the entire range of pulse shapes regardless of the ratio of powers, and some mismatch will inevitably occur. To minimize this mismatch, we rely on numerical optimization of the relative launch powers with respect to the receiver SNR, and we refer the readers to [41] for a more in-depth discussion on the OPC symmetry scaling principles. For convenience, we define the relative input power difference as…”

Técnicas avançadas de projeto e processamento digital de sinais para sistemas ópticos sem repetição de alta capacidade

“…Nesse contexto, a CD pode ser compensada tanto no domínio óptico como no elétrico. Em relação às técnicas no domínio óptico, a compensação pode ser realizada por fibras de compensação de dispersão (dispersion compensating fibers -DCF) [72], filtros ópticos [73] ou conjugação de fase [72]. Entretanto, a compensação no domínio óptico possui algumas desvantagens.…”