I did the simulation of modes profile for different dimensions of the waveguide cross section. I used PML for boundary conditions.
For the simulation results, I expected that the first supported mode is the fundamental TE mode, and second is fundamental TM and then third supported mode is the second TE.
By looking at the mode profile and the fraction of TE polarization, the second supported mode looks like TE mode (the TE polarization fraction is 96). The field profile of the third supported mode is unlike a typical mode profile of fundamental TM mode, although the TE fraction is 4. (This simulation is done with 1u*180nm strip waveguide). The result is shown below. The used simulation file is too large to upload. It can be viewed in wa_sim dropbox link.
Is the result reasonable. Could someone explain it a bit?
Also the negative loss is strange to me.