Theoretical evaluation of the noise growth and of the system performance for a link constituted by a chain of N optical amplifiers with in-line filters

Summary form only given. Summary form only given. Amplified spontaneous emission (ASE) noise is a major limit to the performance of modern day optical transmission systems. A way to alleviate system impairments due to ASE is the insertion of bandpass filters along the line. Soliton pulses have shown excellent stability to in-line narrow-band filtering, and also to sliding of the filter center frequency along the line. The dynamics of soliton signals in the presence of both fixed and sliding filters has been the subject of detailed studies. However, little attention has been given to the dynamics of the ASE growth in the presence of in-line filters. The analysis of the ASE noise growth in a chain of N amplifiers in the presence of in-line filters is the subject of this work. This analysis has been extended to the case of semiconductor optical amplifiers (SOA), where the noise growth, combined with the fast saturation of the amplifier gain, are more effective in degrading system performance. The analytical results have been compared with numerical simulations. Good agreement has been obtained for in-line erbium amplifiers, also considering a high inversion factor. For SOAs, on the other hand, the more complex amplifier dynamics makes the theory quantitatively less accurate, as expected. Even in this case, however, the analytical formulas can be taken as useful guidelines for the design of optical systems.