hfss v12

I am using the eigenmode solver to find the modes in a fabry-perot type cavity, so two mirrors seperated by L with radius of curvature R, where R~L,
I have been finding the modes, but I can't figure out how HFSS v12 determines the polarization of each mode. For example, if you have a cylindrical cavity, how does
HFSS determine which polarization the modes are, since they could be any. Furthermore, the fabry-perot cavity can either be solved using laguerre-gaussian modes (cylindrical coordinates) or hermite-gaussian modes (rectangular coordinates). It looks like HFSS is using laguerre gaussian modes. How does HFSS determine which one to use?

Thanks,

I have the same problem.
Use CST to aboid that problem.

wait. I thought you couldn't create pml boundaries in CST? Is the resonator you simulated in CST open?