Diffractive surface with a two-material grating

  • 26 March 2020
  • 3 replies


I am a new Zemax user and I need to simulate the reflection onto a 2-material diffraction grating. See an example of the structure in attached file.

I have read the several topics on the knowledge base and I know that " the diffraction angle depends only on the period of the repetitive structure [...] and not on the shape of the structure within that particular period".

Then I imagine the best way to do my project is to design a 2D diffractive surface (Period over X axis different than period over Y axis).

Is there another way than making an user-defined DLL to do it ?

Can I code this surface on Zemax easily ?

Also, because the grating is 2-material, how to reproduce this fact with a surface or with a custom diffractive object ?

I have already tried to create the grating pattern by combining several user-defined objects but it ends to be messy and not convenient.

In case, I would be pleased if you would have some advices to give about how to treat this kind of gratings on Zemax.

Thank you by advance for your time3-s20-b0122266803001538-gr3.gif

Best answer by Sandrine Auriol 31 March 2020, 16:29

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Userlevel 6
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Diffractive elements in OpticStudio are modeled by the phase (for more information see How diffractive surfaces are modeled in OpticStudio).

But in 20.1, we added two DLLs made by my colleague Michael Cheng: a step profile grating and a trapezoid profile grating. These DLLs take into account the grating profile. You will find more information about this in that article Simulating diffraction efficiency of surface-relief grating using the RCWA method. These DLLs are only in one direction at the moment (1D).

Let us know if this can help.


Thank you Sandrine.

About the DLLs you are mentionning, is it possible to use them with a previous version of Zemax ?


Userlevel 6
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No I am afraid it won't work with previous versions.