reflection from Al2O3 glass substrate

I want to simulate the reflection spectrum from Al2O3 glass substrate. Here is the schematic.

The x span and y span was 1500nm. The z span was 3000nm. The auto shutoff min was set to be 1e-8.
However, the autoshut did not triggered, the autoshut level was somehow stuck at e-7. After I lowered the autoshut level to 1e-6, I obtained this reflection curve.

I also tried to change the x max bc and y max bc to anti-symmetric and symmetric, the autoshut was triggered at 1e-8 and the reflection curve is like that.

So, my question is

  1. why in the non-periodic case, the autoshut level is stuck?
  2. which reflection curve is the correct one?

(I tend to use the non-periodic bc because later on i will simulate the scattering of a nanoparticle on a substrate)

Thanks for any kind of help.


The best way to check any simulation result will be to compare it to an experimental reflectance curve, since that represents the real-world behaviour of the sample.

In regards to your symmetry conditions. You can follow the following knowledge base article of boundary condition selection:

I would check the result with a periodic boundary condition, so that you can be sure that you have not erred with the boundary condition settings.

Best Wishes,

Vivek (KX Champion)