Hi,
I can briefly explain you my application as follows:
I have a single mode transmitter with 2x40Gbps single mode Multiplexer. The two transmitters are centered at the same frequency i.e. 191.1THz but are orthogonal to each other in terms of polarization. The 80Gbps Polarization Division Multiplexed signal is transmitted through Free-Space over a distance of xkm and is received at a receiver which has a Multimode De-MUX. Here, is where the received signal experiences multimode effects. I have introduced a Linear Multimode Fiber block to add multimode effects before the signal is passed on to the WDM Demux. The two signals are separated on the first arm of the Demux and are to be converted into electrical signals by a MM optical receiver and later BER and Eye Diagram are observed on the Visualizer.
Now, I do not know what do you mean by an idealized model to separate out the modes and by a physically based MM Demux as my knowledge on working with multimode components and fibers is limited. However, I have attached my OptiSystem file for your consideration. I see an error when OptiSystem calculates Spatial Optical Receiver block as the input signal is invalid because it does not have spatial transverse modes(rightly so). I can introduce spatial transverse modes by using Spatial Optical Transmitter but in the laboratory experiment, I have a single mode transmitter so I want to avoid this solution to keep my simulation as close to the lab experiment as possible. What can you suggest in this scenario?
Feel free to ask me if you need more clarification about the setup.
Cheers,
Ahmad