An Algorithm to Speed up the Spatial Power Profile Calculation in Backward Raman Amplified Systems

As data transmission demands grow, long-haul optical transmission links face increasing pressure to increase their throughput. Expanding usable bandwidth through Ultra-Wide Band (UWB) systems has become the primary strategy for increasing transmission capacity. However, UWB systems present challenges, such as the reliance on backward Raman amplification and the complications posed by inter-channel stimulated Raman scattering (ISRS), which causes uneven signal propagation across bands. To address these issues, accurate and efficient physical models are required for real-time optimization, which rely on the knowledge of the power profile. This paper develops a novel, more efficient method for computing the power profile of signals and pumps, utilizing the integral form of the equations with matrix-based approximations. The algorithm achieves up to a thirty-fold average speed increase over conventional approaches while maintaining an error margin under 0.05 dBm. These results represent a significant step forward towards reducing optimization times and enabling more extensive studies in ultra-wide band long haul optical transmission, further facilitating research and commercialization of UWB systems, in an effort to address the growing demand for higher throughput.

Launch Power Optimization in super-(C+L) Systems

We investigate launch power optimization in 12-THz super-(C+L) systems, using iterative performance evaluation enabled by NLI closed-form models. We find that, despite the strong ISRS, these systems tolerate well easy-to-implement suboptimal launch power profiles, with marginal throughput loss.

Optimum Launch Power in Multiband Systems

We investigate the residual throughput penalty due to ISRS, after power-optimization, in multiband systems. We show it to be mild. We also revisit the launch power optimization 3-dB rule. We find that using it is possible but not advisable due to increased GSNR non-uniformity.

Closed-Form EGN Model with Comprehensive Raman Support

We present a series of experiments testing the accuracy of a new closed-form multiband EGN model, carried out over a full-Raman 9-span C+L link. Transmission regimes ranged from linear to strongly non-linear with large ISRS. We found good correspondence between predicted and measured performance.

CFM6, a closed-form NLI EGN model supporting multiband transmission with arbitrary Raman amplification

We formulated a closed-form EGN model for nonlinear interference in ultra-wideband optical systems with arbitrary Raman amplification. This model enhanced the CISCO-POLITO-CFM5 performance by introducing a novel contribution attributed to the backward Raman amplification. It can handle the frequency-dependent fiber parameters and inter-channel stimulated Raman scattering.

Closed Form Expressions of the Nonlinear Interference for UWB Systems

We present a comprehensive closed-form GN/EGN model supporting ultra-wide-band systems spanning 50 THz of optical bandwidth. We show a case-study of 10x100km of SMF where we gradually increase the number of channels across the C,L,S,U,E bands while optimizing launch power.

A GN-model closed-form formula supporting ultra-low fiber loss and short fiber spans

We report on a fully closed-form approximation of the GN model for Nyquist WDM systems that extends the range of applicability of previously available formulas to values of fiber loss and span loss that were not previously covered. In particular, so far, a closed-form formula was available for zero loss, and another for span loss of at least about 7 dB. The new formula is accurate over any fiber loss and any span loss value. The interest for this new formula is varied, ranging from hollow-core fibers to improving modeling of standard systems that present lumped loss along installed spans (such as splices or connectors).