Analytic and numerical study of pulse broadening in nonlinear dispersive optical fibers

Pulse propagation in optical fibers is considered after including the effects of chromatic dispersion and nonlinearity. To estimate the extent of pulse broadening, an analytic expression for the pulse width is obtained under certain simplifying assumptions. Its range of validity is discussed by comparing the analytical prediction with the numerically calculated pulse width. Results are presented for 1.55-μm optical pulses propagating in conventional as well as in dispersion-shifted fibers. Our results show that for relatively wide pulses the nonlinearity broadens the pulse considerably over the linear case, thereby reducing the bandwidth of optical communication systems. For sufficiently short pulses we have found that the nonlinearity can give rise to pulses narrower than the linear case at the zero-dispersion wavelength.