Hi Vignes,
OptiSystem does not yet have the capability to do that sort of multimode multiplexing. Currently the doped fiber will expect a signal without any spatial information and inside component the spatial profile will be applied, however this means you cannot transmit different modes with different time domain signals. The time domain signal travels together over multiple modes.
The paper that you attached, where they have a doped profile as a function of radius, can be simulated, but unfortunately the different spatial channels cannot. This area in Multimode Multiplexing and amplification will undergo a large update over the next year, since it is a popular subject!
Regards