Dear Ravil Thanx alot for your reply
Actually my Project has two parts: Downlink and uplink. In downlink the fiber length is 110km but the results are good with no timing jitter.
But the picture which is shown in attachment: is of uplink. And the fiber length in this case is 75km. But when i reduce the fiber length i-e 25km then just q Factor increases but the eye diagram remains same with same timing Jitter as shown in attachment above Pic 1.
I am not using 3R regeneration at the end in Receiver.But using Low Pass Rectangular Filter as shown in circuit.png