Hi! Gagan
Since you are working on FWM, then for sure there are effects of using different modulation formats on FWM .You can find lot of articles on this particular topic.Data rate is independent of FWM as reported in most of the articles.Advance modulation formats are bandwidth efficient and less prone to the dispersion effects due to phase shift in consecutive bits.This in turn increase total transmission length of the system .
Take a look at these papers
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6518625&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D6518625
http://airccse.org/journal/ijdps/papers/1111ijdps25.pdf
http://www.ijera.com/papers/Vol4_issue1/Version%202/V4102176181.pdf
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CC8QFjACahUKEwjo8ra654XIAhWQGY4KHdJJBQY&url=http%3A%2F%2Fwww.aast.edu%2Fpheed%2Fstaffadminview%2Fpdf_retreive.php%3Furl%3D53905_66_80_Paper%252083.pdf%26stafftype%3Dstaffpdf&usg=AFQjCNEi1HwaevSXDY8D8_-pzXrkc3ymxQ&bvm=bv.103073922,d.c2E