Comprehensive model for studying the suppression of four wave mixing in WDM optical transmission system

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.