Amrita Pati
Ansys Employee

Hi Gukhyun,

  1. If both the simulations are set up correctly, the unit cell results should converge in FDTD and RCWA.
  2. As far as I know the target phase profile in this case is obtained from an analytic equation. A hyperbolic equation is used to approximate the phase. I haven't spent a lot of time on this App Gallery Example, it might take me while to go through it and figure out what it going on. I will get back to you with more details. But in the meantime, there is a webinar on this topic which can be requested here: Zemax and Lumerical Part 2 from nanoscale to macroscale optics and back. You would receive a email with the video link once you register on the above page.Please go through it and let me know if you have any further questions.