Guiding-center soliton in optical fibers

For a relatively long optical pulse in a fiber with a dispersion distance z(0) much larger than the loss distance, a soliton cannot exist in an ideal sense. However, with a proper choice of the initial amplitude and amplifier distance z(a), a nonlinear pulse (a guiding-center soliton) propagates like a soliton over a distance much larger than the dispersion distance when it is periodically amplified at distances much shorter than the dispersion distance. The guidingcenter soliton is shown to satisfy the nonlinear Schrodinger equation with a correction of order (z(a)/z(0))(2). Numerical examples supported by analytical results are presented for distortionless propagation of the guiding-center solitons with a pulse width of 40 psec in a dispersion-shifted fiber of D = 1 psec/(nm-km).