Hello All,
As far as your query is concerned I will suggest you to use advanced modulation formats like: CSRZ, DRZ and MDRZ at transmitter end because CS-RZ format has high tolerance to the mixed effect of self phase modulation(SPM)and group velocity dispersion(GVD) and has narrow erpedestal shape of the optical spectrum than the conventional RZ format.
Also in case of CSRZ transmitter,the NRZ optical signal after MZ modulator goes through phase modulator, The duobinary precoder used here is composed of an exclusive-or gate with a delayed feedback path. DRZ formats are very attractive,because their optical modulation bandwidth can be compressed to the data bit rate B,that’s,the half-bandwidth of the NRZ format2B. The generation of MDRZ signal is almost identical to the DRZ signal,except the delay and add circuit is replaced by a delay-and-subtract circuit. In the duobinary signal used earlier where the phase of bits‘1’s are modified only after a bit‘0’appear where as in the modified duobinary signal the phase is a alternated between 0 and p for the bits‘1’.The phase of all the‘‘zero’’bits are kept constant and a 180 degree 1 phase variation between all the consecutive ‘ones’ is introduced.
I hope you find it helpful.
Thanks