Efficient Three-Step Amplifier Configuration Algorithm for Dynamic C+L-Band Links in Presence of Stimulated Raman Scattering

Abstract

We propose an efficient three-step amplifier configuration algorithm to improve and maintain the generalized signal-to-noise ratio (GSNR) performance of dynamic C+L-band links in presence of amplifier spontaneous emission (ASE) noise, Kerr nonlinearity and stimulated Raman scattering (SRS) using erbium-doped fiber amplifiers (EDFA). In step 1, we derive sub-optimal signal power profiles at the beginning of each span using the local optimization global optimization (LOGO) strategy [1] that takes into account ASE noise and Kerr nonlinearity. The effect of SRS, which is the dominant impairment in wideband transmissions, is compensated through amplifier gain pre-tilt of each span in step 2. In step 3, we use the closed-form inter-channel stimulated Raman scattering Gaussian noise (ISRSGN) model [2] to compute the GSNR of a multi-span link as a function of the inline amplifier gains and tilts and propose an iterative gradient ascent optimization algorithm to maximize the mean GSNR and minimize its standard deviation across the C- or L-band. Simulation studies for homogeneous-/heterogeneous-span links, static full-channel loading and dynamic loading due to gradual channel additions or sudden fiber cuts show that compared with other GSNR profile optimization methods, the proposed algorithm can achieve similar GSNR performance but only require execution time in the order of seconds. The effectiveness of the proposed algorithm in restoring/improving GSNR performance for an 8-span C+L-band link is experimentally verified for a scenario imitating a sudden fiber cut induced-channel disruptions. We further show that different optimization functions such as maximizing the minimum GSNR across the C+L band can be used in practical settings, and thus the proposed algorithmic framework is adaptable to different network control and management objectives.