Fresnel Equations Simulation in 2D: How to Avoid Side Entry in Comsol?

[MarcelComsol]

Hi there,

I'm failing in simulating the fresnel equations in 2D with Comsol.

As you can see in the model added to this post, the reflectance and transmission in the global plots both for TE-waves ("Port, senkrecht polarisiert", Plot "Reflektion und Transimission, senkrecht") and TM-waves ("Port, parallel poralisiert", Plot "Reflektion und Transmission, paralell") seems to be correct for small angles of alpha. But for bigger angles of alpha, the simulated values differ strongly from the analytical solutions. I suspect that the wave from the upper port is also entering from the sides of the dielectrica (side 1 and 6), since we have also an electrical field in the dielectrica for alpha equals 90 degrees(see picture below). How can I avoid the electromagnetic wave entering from the sides 1 and 6 (i chose floquet periodic boundary conditions)?

Picture above: TM waves, alpha=90 degrees, but still a wave is entering my dielectrica(the lower half)

I would be very happy about every help in this problem!
Best wishes

model: https://drive.google.com/open?id=107LINBOhmZtR_uzkJhYKgNb8POFVLMX6

 

[MarcelComsol]

I was able to solve the problem in the meantime :-)

 

[DrClaude]

I was able to solve the problem in the meantime :-)

Can you tell us how you did it?

 

[MarcelComsol]

Hi DrClaude

The problem was the propagation constant of my ports...

My current understanding of the propagation constant is that it must correspond to the vertical component of the wave vector. It must also have a positive sign, otherwise the wave will propagate upwards.
(Provided that the wave should propagate in the negative y-axis and the coordinate system is defined that the y-axis points upwards)