Hello gaganpreet kaur,
I have given following points to reduce the effect of non-linearities because WDM system design for high number of channels and ultra-narrow spacing can only be realized by taking these factors in account. However, you want to exploit the effect of non-linearities you can use high power. Study of non-linearities was part of my previous study and it would be my pleasure if i can help you in this study because this is the great area of research and my command is good in this particular area.