Guilin Sun
Ansys Employee

not necessarily. I am not sure if you are aware that, in photonic waveguides, unlike the weak waveguide, the polarization is not purely TE or TM, as it has at least the non-zero axial field component.  The concept of TE/TM has been eveloved.

Please visit this link for TE Fraction

In general, people do not use TE fraction to design a waveguide, in most cases. 

Of course, if your goal is to design a waveguide that requires 100% TE fraction, you can do so.  But it might not be exactly 100% as you can check the other transversal component, which in many cases is non-zero.