Hi Irfan,
This file is OptiSystem SAC-OCDM sample as far as I am concerned (so you can find it in OptiSystem samples). I ran the simulation and it went smoothly with acceptable results except for the third user (which you should first enable in the simulation BTW). If you cannot open the file or do the calculation, this is a technical issue and you should contact Optiwave, which will probably answer after the weekend.
I suspect something might be wrong with the way the third code is generated by FBGs. I haven’t worked much on SAC-OCDMA, but if you are interested to know how the codes should be generated, I suggest you thoroughly go through the related comprehensive discussion in the link below:
Regards