HELLO JYOTI..
It is alright this happens sometimes while typing but anyway your system will work if the bit error is close to zero.. I twill be an ideal situation when your BER will be zero which is not possible..
To improve your eye diagram try increasing the global symbol rate or maybe power for that reason but it will introduce more itineraries..
u can also use optical amplifiers with distance upto 5m or any amplifier.. try these things and see for the results. I hope it will help.
Thanks & regards