Hi, I am new to the Lumerical FDTD. I am trying to quantify the phase shift that a nanopost exerts on the incoming wave as described in the paper https://arxiv.org/abs/1711.07158 Fig. 1b and in the paper https://arxiv.org/abs/1708.01972 Fig. S2 b.

I also look through this post in KX. It seems that the phase retardation is calculated for a single point. I wonder how to quantify the phase delay that the post introduces as a whole device? So much thanks!