can anyone explain how to do S-parameter analysis when the period structure supports multiple orders?
The following post discusses how you can modify the S-parameters analysis group to extract S-parameters by only looking at the amplitude and phase of reflected and transmitted light in the 0th grating order:
However, I think it’s not clear whether this approach of only considering the 0th grating order is a method which is standard. It may be worth looking into some publications to see what approaches they use for calculating the S-parameters when multiple grating orders are supported.
Hopefully it helps!