Guilin Sun
Ansys Employee

Hi, Lumerical has dedicated  English, Chinese and Korean forums:

Next time please post in the proper forum in order to get quick reply.

A1: Since 2D is a simplified method and the actual device is 3D

A2: You can optimize it but from my experience. limited to process techniques, people have fixed depth parameters.

A3: In optimization the algorithm will pick up a set of parameters to be optimized for each generation. So they are optimized all tegother. Please refer