Hi AAsif,
Although we have three dispersion compensation techniques namely pre, post and symmetrical.
I like to add basic elements and parameters of dispersion compensation :
Fiber Bragg gratings (FBG) are one of the important methods of
dispersion compensation. They reflect different frequencies from
different length, at the end, different frequency components of the
signal will see different phase delays. They have short length (~10-
15cm). They are not very suitable for WDM applications because
of their narrow bandwidth (~0.1-5nm). They have very low loss
like 1dB in 80km. Their short length provides less nonlinear
operation.
Dispersion-compensating fibers (DCF) are another important
method of dispersion compensation. They operate by insertion of
fibers with dispersion of negative slope, high absolute value. Their
lengths can be 17-20km. Lengths are too high that nonlinear
effects cause a problem. They have wide bandwidth suitable for
WDM applications (~20nm).
Thanks,