Yes in this case I understand. But I wonder if I export the data of waveguide properties to INTERCONNECT in a mode waveguide, how about the group index? Does the INTERCONNECT will calculate corresponding group index by itself?

This point is very important for me beacuse I am now doing a ring modulator simuation. I need to calculate the EO response and eye diagram, for getting these two results, group index of mode waveguide is very important.

You could see this post:

Different result of ONA in INTERCONNECT for impulse response and scattering data (ansys.com)

It seems that I cannot set the group index directly in mode waveguide element, so how should I do in this case?

Thank you and wish your reply!