Complete analysis of sideband instability in chain of periodic dispersion-managed fiber link and its effect on higher order dispersion-managed long-haul wavelength-division multiplexed systems

We present for the first time a complete theoretical analysis of sideband instability (SI) that occurs when two kinds of fibers with different characteristics are concatenated to form a dispersion-managed fiber link. In the analysis, the following three cases are taken into account: case (a) when a dispersion-management period is larger than an amplification period, case (b) when the two lengths are equivalent, and case (c) when a dispersion-management period is smaller than an amplification period. We find that the SI gain peak appears at frequencies determined by the larger of the two variation periods. Moreover, for all three cases, the magnitude of the SI gain reduces with the increase in strength of dispersion management. Next, we focus on the fiber link using the combination of standard single-mode fiber and reverse dispersion fiber, which is widely used for simultaneously compensating second- and third-order dispersion. By computer simulation, it is shown that in wavelength-division-multiplexed systems, SI still induces significant degradation in channels located at frequencies where SI induced from other channels arises. By reallocating the channel frequency to avoid the SI frequency, the transmission performance is improved significantly.