Guilin Sun
Ansys Employee

Depending on your purpose, you can use Metal BCs to quickly get some lower order of modes, such as the fundamental mode. you can also use PML to get the only propgation modes. However, you may need to signifiantly increase the number of trial mdoes in order to get ride of PML modes (not shown). If yoy believe the mode number can reach 100, and you want all of the modes, you may need to use 200 or more for the trial modes.

If you only need the modes with certain effective index, you can set the range of index, or begin from a certain index value (the result can be beyond this value).

Please try and see if you can get sufficient number of modes.