Discussion Forum

Hello everybody,

I have a question about scatterer on substrate example.
The Structure is simple: a metal scatterer on Si substrate.
Since I have just seen that scattering, absorption, and extinction cross sections are calculated for scatterer, is it meaningful to calculate reflection in this structure? We have experimentally measured reflection from our sample. So, I need to calculate reflection by simulation to compare results.
I calculate reflection just by defining a surface in front of structure and integrate the pointing vector to get power flow and I subtract it from incident power to get reflected power and then I divide the reflected power over incident power to get reflection.
when I do not have scatterer it works fine. It shows exactly the reflection calculated by Fresnel equation for Air-Si interface. I also tried putting SiO2 and still without scatterer, it works fine again and results matche well to results by Transfer Matrix Method (TMM).
But, when I put scatterer on Si or even on SiO2 it does not show any change in reflection spectrum while we observe resonance in experiment. By looking at electric field profile I can see the interaction of light with scatterer and I can see a dipole on it, but no resonance in reflection.
I tried this structure both by putting Fresnel formula as my background field and also by using two step study method. Both results are same and do not show any resonance in reflection.
So now I am thinking that maybe the way I am calculating the reflection is not right since scatterer may scatter light toward side PML boundary and I can not collect and integrate them in the defined surface in front of structure. Another thing that I am thinking of is this: maybe the experimental results are wrong.
I appreciate if you guys share your experience with me.

Thanks,
Mohammad