Is it possible to model an incident light beam with a spot size of, say, 20 microns? In particular, is it possible to do this for a beam incident on an infinite array (modeled using floquet boundary conditions)?
Essentially, I want to model an array of resonators on a substrate with an incident beam that only covers an area of radius 20 microns, similar to what would be the case in a physical measurement, and measure the transmittance through the substrate.