How to calculate the efficiency of a diffraction grating

Hi

I am very new to HFSS and i am trying to calculate the efficiency of a diffraction grating using this software.
I create a unit cell of my grating and assign 2 Floquet ports, because i need to calculate the transmission as well as the reflection. Physically, when light incident on a diffraction grating, it diffracts to different angles when transmitted through or reflected from the grating. In optics they called as R0, R+1, R-1,R+2,R-2.... (R means reflection). The same applies for transmission T0, T+1,T/1... To make the simulation simpler, i excite only TE00 mode (ONLY one mode).

Now i would like to know how can i calculate those orders using S-parameters in HFSS.

I know that mag(s(floquetport1:1,floquetport1:1)) means S11*S11 which is the reflected power, but i dnt know if this is the R0 or this is the total R=R0+(R+1)+(R-1)+...
Does anyone knows how i can calculate R+1 or R-1 ?
Can anyone help me?


Thanks

Hamed

You will set the number of diffraction modes in your Floquet ports. Then you can output the diffraction efficiencies as S21, S31, etc...