Hi Sanjeev Kumar,
I think you have done some major mistakes because you are using continuous phase frequency shift keying (CPFSK) sequence generator as seen from the attached image and applying it to modulate the optical signal using MZM modulator. but at the receiver side you have not done the decoding of the CPFSK sequence. I am not aware of this system. I have to try from my own to have a confirm answer.
Regards,
Dhiman