We do have a mode solver that can simulate that kind of waveguide. I have attached a picture below with some recent results. This mode solver is OptiMode, and is currently sold packaged together with OptiBPM and OptiFDTD. You can try this mode solver with an evaluation of either OptiBPM or OptiFDTD.
If you want to perform more simulations using the calculated modal fields, I can suggest which software would be better suited to your needs. All I need is a rough outline of your design or a relevant research paper.