I have an additional question to your original post. I am simulating Dense Wavelength Division Multiplexing in OptiSystem and I have a multimode De-MUX and a MM Rx. I have, so far not found any such components in OptiSystem. Could you please comment on that if you know of one?
And, are you trying to model a multi-core fiber all alone in OptiSystem or you have an interface with MATLAB where you get the input from and simulate the multi-mode effects accordingly in OptiSystem?
Good Luck and Cheers,