Learning Forum

[qiankun.liu]

Dear Ansys employee:

I have built a eme simulation to calculate the coupling length of DC (WG material: SiN, cladding: SiO2, WG width: 1um, WG height: 400nm). To restrict the simulation window, I choose to use rotated eme ports (port 3 and port 4). The theta angle of port 3/4 is -45/+45 deg. However, the calculated eigenmode for port 3&4 isn't a mode for a WG cross section of 1um x 400nm (please see the image below). How can I resolve this bug? Thank you!

[Guilin Sun]

As long as you set the port position, area, angle and EME mesh correctly, it should give you correct mdoe. I tested one case and it works fine:

it seems the waveguide dimension is small compared to simulation region, so correct settings mentioned above are important, in particular the number of mesh cells or mesh size.

[Guilin Sun]

From your first screenshot, it seems both z and y meshes are not sufficient;

from your second screenshot, it seems y meshes are not sufficient.