Guilin Sun
Ansys Employee
When the yz span changes, the result should not change that much like from 0.836 to 0.996. Please use FDE to check the mode profile, and see if the mode profile is truncated or the magnitude at edge is large, say 1e-3 or 1e-4. To save time ys spans may not necessarily the same. Of course you can still do the span sweep to see if the result converges. Other factors you need to consider are PML reflection, autoshutoff min. Make sure the PML has roughly half wavelength thick (you can measure it using the "Ruler" tool).
Please make sure that the waveguide yspan is proper
You can measure the transmission to quantify the convergence.