Abstract:
With increased channel capacity, launched optical powers, bit rates and number of
wavelength channels, the cross phase modulation (XPM) has become the most
important nonlinear effect and limits system performance. On the other hand, group
velocity dispersion (GVD) is one of the linear effects in the optical fiber that also
restricts bit rates. In high bit rate and first order GVD compensated system, the effect
of second order GVD become significant and also play a critical role in limiting the
system performance. As a result the combined effects of XPM with first- and second
order GVD cause further deterioration of transmission performance in a WDM
system.
In this research work, analysis has been carried out to find expressions of pulse
broadening factor as well as normalized output by solving the nonlinear Schrodinger
equation (NLSE) analytically, considering the effect of XPM with first- and second
order GVD. The results are evaluated at various data rates, different input powers as a
function of transmission distance using standard single mode fiber (SSMF) and large
effective area fiber (LEAF). The pulse broadening is strongly dependent on the effects
of XPM with first- and second order GVD. Though at shorter distance and low bit
rates the effect of second order GVD is not noticeable but as the bit rate increases its
effect becomes significant and impacts the system performance. It is observed that the
data rate and fiber length have higher impact on pulse broadening than the input
power. The results are computed for SSMF and LEAF using analytical derivation and
numerical simulation done through split step Fourier method with same data rate and
input power. It is found that the effects of XPM with first- and second orders GVD is
more effective in SSMF fiber than that of LEAF fiber. Thus the findings of this work
can predict the amount of performance degradation due to the effects of XPM with
first- and second order GVD and may be helpful to design high speed long haul
WDM fiber-optic transmission link.
