Optical wave breaking cancelation and formation of quasi-parabolic ultrashort pulses

We consider formation of ultrashort quasi-parabolic pulses in conventional silica fibers both in the near and far fields of dispersion. Through solution of nonlinear Schro¨dinger equation we show that in case of high soliton order N the optical wave breaking effect, occurring in optical fibers during ultrashort pulse propagation, is canceled in the far field of dispersion. This is accompanied by nonlinear pulse reshaping from initial Gaussian shape towards nearly parabolic pulse with almost linear chirp. We suppose that this process is associated with relaxing conditions required for optical shock formation. Divergence of the resulted pulse shape from the parabolic one is quantitatively examined. Optimal conditions for soliton order and fiber length required for nearly parabolic shape formation is given for case of low N.