I would like to model the emission from a multimode optical fiber.

I found examples in the Knowledge Base on how to calculate fiber coupling efficiency using physical optics. However, I instead would like to find a way to look at the emission pattern of a multimode fiber using Zemax. A multimode calculation would be onerous. But this output could instead be treated more simply as a total internal reflection within a long glass rod. Can Zemax handle that?

In particular, I want to get a uniform output, which is known to depend on the entrance angle of the light coupled into the fiber, as shown below. I wish to calculate these patterns. 

Thanks,

-Larry