Abstract
Several properties of nonsoliton evolution are investigated aiming at the possibility of using nonsoliton inputs as signal carriers in soliton-based optical fiber communications. Here, by nonsoliton pulses we mean nonlinear pulses, not exactly solitons. Our numerical results show that nonsoliton inputs can propagate stably while evolving into an oscillatory soliton-like central part and dispersive tails distributed on both sides. This is true when the fiber loss is considered and the Raman compensation technique is applied. It is also shown that when nonsolitons are used as inputs, the interactions between two neighboring bits are stronger than that between two ideal solitons. These interactions include the interference between the central part and the dispersive tails from the neighboring bits. This interference causes fast oscillations superimposed on slower soliton oscillations. The bit-bit interactions also include the attraction between two neighboring pulses. It is found that this attraction becomes stronger due to the existence of the dispersive tails. The cross-phase modulation between two channels during soliton evolution produces two effects: 1) the pulses become asymmetric; 2) the pulse propagation speeds are changed. Both effects are attributed to the oscillations of the pulse shape during evolution. Even with these effects, the pulse can still propagate stably over a long distance. The results in this research show that it is quite promising to use nonsoliton pulses for the soliton-based fiber communications. © 1990 IEEE