Hi shahbaz ,check the system file.I have made it with following modifications in your system
1 i have ysed wdm transmitter with 193.1 starting freq. With 100Ghz channel spacing( just for my convenience) however you can change it according to you.
2 power i have used 0 dBm for each channe
3 fiber as it was in your system
4 i have used a 1×4 power splitter due to detection of 4 different wavelnghts.you can increase it for each wavelngth also in case to increase no. Of users for each wavelength
5 Bessel filter at each channel with 193.1 193.2 193.3 193.4 freq. Respectively in order to detect diff. Signals from specifuc wavelength.
6 i havnt changed upstream
Hope it will answer to your all problems.now you can try fabry part filter if you want to use.
Cheers !