Local balance between the dispersion and the selfphase modulation and the pulsewidth can be conserved when picosecond solitons propagate along a dispersiondecreasing fiber which group dispersion exponentially decreases along the fiber length at the same rate as the energy loss. However

fabricating the dispersiondecreasing fiber with perfect group dispersion distribution is not easy. A scheme of stepdispersiondecreasing fiber substituting for the dispersiondecreasing fiber has been investigated by solving numerically the generalized nonlinear Schrodinger equation in this paper. The results of the numerical simulation shows that solitons can stably propagate in the loop composed of the stepdispersiondecreasing fibers and the sliding filters.