Floquet boundary conditions in multilayer structure.

Hi all,

I am trying to simulate a multi junction solar cell (for eg: Si/SiO2/Al) and trying to study the electromagnetic behavior of it. For periodic conditions I had used floquet boundary conditions,

I think giving the k-vectors for each layer in the structure in the floquet boundary conditions box is necessary, as the refractive index is different for different layers in the structure. Because of this the source and destination wave vectors are different. Am I right?
or
Giving the incident k-vector is correct?


Thanks in advance
Regards
Binoy Chacko