Nano plasmonic 2-D array- k-space dispersion (or detection angle sweep)

I have a plasmonic array of gold nano disks (arranged in 2D square lattice) on glass. I need to get the dispersion in k-space when the array is illuminated by white light source from all angles through an objective of 0.8 or 0.9 NA.

Can I vary the angle of detection in the fdtd set up with periodic boundary condition?

Any insights?

Thank you very much.

as the 2-D array is a kind of grating ,you can Grating order transmission.
The different orders of the grating have a specific angle of reflection or transmission.