Abstract:
Fiber nonlinearity can cause interactions and severe crosstalk among co-propagating wavelength
division multiplexing (WDM) channels in high capacity optical fiber communication system. The
crosstalk between channels leads to degradation of the bit error performance of the transmission
system. One of the mechanism of this crosstalk is four wave mixing (FWM) caused by the fiber
nonlinearity. From different research outcome it is reported that FWM strongly depends on channel
spacing, input power, dispersion and core effective area of the fiber. It is essential to evaluate the
effect and actual performance degradation due to FWM crosstalk as large amount of optical power is
carried by the modern high bit rate WDM channels in long haul communication system. In this
research work, a comprehensive analytical model has been developed for evaluation and suppression
of FWM effect in a multi-channel fiber-optic transmission system. Using the developed model,
FWM suppression performance is evaluated in terms of crosstalk power for 3-different types of
communication grade fiber. Through investigation it is found that the amount of FWM crosstalk is
lowest in standard single mode fiber (SSMF) than the dispersion shifted fiber (DSF) or large
effective area fiber (LEAF). FWM crosstalk also decreases as the channel spacing or effective area
increases. Input power and fiber link length also plays a significant role in FWM crosstalk
generation. From the analysis and performance evaluation it can be inferred that FWM crosstalk can
be minimized by carefully choosing different system design parameters of fiber for high bit rate
transmission system.
