First of all, you are welcome to the forum the same way I would equally welcome myself after a long break due to a number of task at hand. Just as Lalit Verma has already said, the forum is more of a way to implement your design using optisystem softwares and some others. There are some factors you need to consider when talking about SAC-OCDMA. One is how many users, which light source do you want to use (LED or multi-wavelenght laser,white light), which code do you plan to use, (eg, OOC, MQC, KS, MS code) and also the decoding techniques you have chosen to use.
Whichever way, You have the light source (example LED), the spliter(divide into number of users), the FBG to implement the chosen code, modulator to modulate the light using the bit sequence from the PRBS with a specific modulation format ( such as NRZ, RZ, and other advance modulation formats such as QPSK, DPSK etc). Then you need a power combiner/coupler to couple the signal from different users. then you select your channel of communication (free space optics (FSO) or fiber). At the receiver, you equally need a splitter, to divide the combined signals into the number of receivers. Then you apply your chosen decoding techniques e.g(direct decoding, complementary, AND decoding or any other you have chosen). after selecting the decoding measure, you need a photodetector (to convert to electrical signal), low pass filter (to remove noise) and also BER analyzer (which gives you error rate by comparing your received signal with the transmitted one, then gives you the rate of error in your system. If you can recollect, A minimum BER of 10^-9 and below e.g (10^-10, 10^-15, 10^-18, 10^-30 etc) is the standard for effective communication. You can modify the parameters to suit your design. I hope the explanation helps. Kindly signify if you need more help. There are professionals like Ravil, Samson, Optiwaves teams, and others to help with more information.