Propagation characteristics of chirped soliton in periodic distributed amplification systems with variable coefficients

Propagation characteristics of chirped soliton in periodic distributed amplification systems with variable coefficients are investigated by using the split-step Fourier method. The soliton pulse still maintains soliton characteristics after propagation in the system. The shape of output spectrum is still with a single peak. The temporal FWHM of an unchirped soliton performs a slight oscillation with the increase of propagation distance. The oscillation amplitude is slightly increased with the increase of the gain or loss parameter σ. The chirped soliton is obviously and periodically compressed and broadened with the increase of propagation distance in the system. The lager the value of chirp parameter |C| and σ is, the greater the variation of temporal width with the distance is. The effect of chirp on temporal width of soliton in a amplification system is greater than that in a loss system. Three types of numerical experiments show that the soliton with different perturbations can stably propagate along the fiber. In practical applications, one can obtain a suitable soliton pulse by controlling the parameters of the fiber system.