On the impact of launch power optimization and transceiver noise on the performance of ultra-wideband transmission systems [Invited]

Ultra-wideband transmission is a promising, cost-effective solution to meet the increasing demand for data traffic in optical fiber systems. However, system performance and quality of transmission (QoT) are limited by fiber nonlinearity, in particular, interchannel stimulated Raman scattering (ISRS), leading to a power transfer from short to long wavelengths. As the result, per-channel launch power optimization is required to maximize the system throughput. In this paper, we investigate how the transceiver noise and launch power optimization impact the total throughput and the per-channel QoT for transmission bandwidths of up to 20 THz, using the S-, C-, and L-bands. To measure the gains through the optimum launch power profile, a spectrally uniform launch power is used as a baseline. Through experimental analysis and theoretical modeling, the main limitations constraining the achieved data throughput of 178 Tb/s over a continuous bandwidth of 16.83 THz and 40 km were investigated. The impact of the launch power optimization and the transceiver constrained signal-to-noise ratio (SNR) are analyzed and compared, and the approaches to overcome data throughput limitations are considered. An extensive theoretical investigation for different system configurations is described, demonstrating the trade-off between ISRS impact and transceiver noise. The former degrades the QoT and increases the gains in performance obtained by optimizing the launch power, while the latter reduces these gains and the SNR variation across the bandwidth, with a major impact over short distances.