Find the modified file, i simply tried to get acceptable results for downstream.Now with the changes in SOA , i got 10^-10 value of BER for first channel in DS.Results are very good for upstream even though i have used same SOA for both the directions.Changes that i have made are as follows
Injection current of wideband traveling wave SOA 0.03A
Active length 5e-7
optical confinement factor 0.3
input coupling loss 0dB
outpot coupling loss 0dB
Varied values are in limits of SOA as shown in tutorial
Thank you