Generation of fundamental soliton trains for high-bit-rate optical fiber communication lines

The authors present a method for the generation of high-quality soliton trains at a high repetition rate of gigahertz to terahertz range. During nonlinear propagation of a continuous-wave (CW) dual-frequency signal through a fiber with effective amplification, a train of practically noninteracting fundamental solitons is formed. It is shown that the effective amplification can be achieved as in usual fibers with an actual amplification as well as in fibers with nonuniform parameters along the fiber axis. The method is demonstrated experimentally. Dual-frequency 25 ps pulses at lambda =1.55 mu m are reshaped into 0.2 THz combs of 0.49 ps solitons in fiber with slowly decreasing dispersion. It is also shown that stimulated Brillouin scattering (SBS) can prevent a CW soliton train transmission through optical fibers, and suggests a method for suppression of SBS.>