Quasi-stable soliton transmission in a long-distance fibre link with periodic dispersion management and lumped amplifiers

Nonlinear pulse propagation in a fibre link with periodic dispersion management (DM) is investigated, taking into consideration the effect of fibre loss. The mechanism that the quasi-stable soliton can exist in a dispersion-managed fibre is revealed. It is found that in the lossless case more energy is required for forming a quasi-stable soliton than the regular soliton in a uniform fibre system. However, when fibre loss is included, and for sufficiently large amplifier spacing, the required soliton energy in the dispersion-managed system is found to approach the same value as in a uniform fibre system, and thus the potential advantage of increased soliton energy in a DM fibre link is diminished with fibre loss. The shape of such a quasi-stable soliton is a nearly hyperbolic secant with loss but more Gaussian-like without loss.