How to calculate the phase of a nanopost?

#1

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!

#2

Hi @ztk18

We use a point time monitor to calculate the phase. This is because time monitor records the electromagnetic fields (both magnitude and phase) at a mesh cell (Yee cell) as a function of time. This means that we can study how the field is modified at a point in the presence of nanospot. You can obtain the information about the point where the phase is calculated from the paper.

#4

(1)where to put the point(the axial and lateral position)?
(2)and why monitoring the evolution with time rather than the stable field distribution?
Thanks again!

#5

Hi @ztk18

1. I checked the attached papers, but still not quite sure where this point is located. It is possible that the authors measured the phase in the focal point. There is also phase profile of the metalens which is related to the design of the metalens and should not be confused.

2. I am not sure what you mean here. By Fourier transforming the results of time domain monitor (i.e. E(t) and $\phi(t)$), you can obtain the phase information as a function of wavelength (i.e. E($\lambda$) and $\phi (\lambda)$). I think authors refer to $\phi (\lambda)$ here.