Alistu i need to understand theoretical relationship between WDM transmitter BW and MUX bandwidth.i was unable to open the file this hour coz optisystem is available only during working hours at college . but i have never optimized mUx BW and a s result many times i received no output BER or Eye diagram but admitting it i was not even aware of this thing. i will try on my design but i need to know criteria of matching bandwidth of MUX/demux with WDM transmitter BW.