This is a sequential surface DLL that models a realistic slant grating by using RCWA. The parameters for this sequential surface is mostly same to the same model in non-sequential mode, where details are introduced below.

https://support.zemax.com/hc/en-us/articles/1500005578722-Simulating-diffraction-efficiency-of-surface-relief-grating-using-the-RCWA-method

The main difference to its equivalence in non-sequential mode is only one diffraction order is allowed in sequential mode. If simulation of multiple orders is desired, users can use multi-configs to work it around.

The DLL can be downloaded by downloading and opening the attached ZAR file. The corresponding DLL will be automatically extracted to the folder \Document\Zemax\DLL\Surfaces\

Note this DLL is locked to only Premium and Enterprise in Ansys Zemax OpticStudio. Standard and Professional license editios are not allowed. Legacy Zemax OpticStudio is not allowed either.