Reduction of Four Wave Mixing Effect in an Optical WDM System by Controlling Channel Spacing and Chromatic Dispersion

The performance of an optical wavelength division multiplexed system is analyzed by taking the Four Wave Mixing (FWM) effect into account. The effect of chromatic dispersion and channel spacing on the FWM efficiency are evaluated. It is found that the efficiency of FWM generation can be greatly reduced by making the spacing between channels unequal. Also nonuniform distribution of chromatic dispersion along the fibers in the communication link can be utilized to overcome the limitations imposed by the FWM process. The probability of error and penalty are evaluated theoretically, and hence the allowable input power is calculated for the optical system. A comparison among various combinations of channel spacing and dispersion shows that the system with unequal channel spacing and nonuniform chromatic dispersion offers the best performance with high input power at large number of channels.