"This depends on customer's goal. Some may want to have different result, eg, to couple with other waveguide/fiber etc." What would be design constraints if I am designing to couple to fiber? I understand that smaller waveguide leads to confined mode but then again wouldn't E field of mode be leaking outside the core to clad region, decreasing Neff? So my design goal is to design waveguide with biggest core size which can propagate only one mode TE?
I have two more doubts:
We design MZM waveguides for single mode(preferable TE), right? Now considering the direction of propagation is in Z direction, for TE Electric field will be either in X or Y direction. In simulation which TE I am looking for, is it TE polarized in X or Y? Because I think TE polarization fraction is close to 100% only for TE in X direction in Lumerical. So wouldn't it be wrong to say that TE polarization fraction should be 100% for TE polarized light, I mean it could be Y polarized also.
What is the purpose of TE/TM fraction? suppose its value is x/y so x should be close to 100(most of the power in electric field should be in transverse direction) but what about y field? What is the significance of this value?