Hi Hamza Ali Abbas Khan,
I suggest you to please refer to following link(s):
The following tutorial of optisystem describe the library of spatial optical sources and transmitters. These components have the ability to include transverse mode profiles in the optical signals.
The spatial transmitters are “ready-to-use” components that encapsulate an optical source or transmitter and a transverse mode generator.
There are two categories of components in the library:
spatial optical sources/transmitters
transverse mode generators.
For multimode simulations, there are additional parameters that will define the space window for the transverse mode profiles. These parameters are the Space width X and Y and the Grid spacing X and Y, and are available in the global parameters window
Lesson 8: Optical Systems — Working With Multimode Components
Thanks,