Metasurface phase calculation from s-parameters

Hi.

I’m trying to calculate a phase shift by metasurface through a s-parameter analysis.
test_paper.fsp (67.6 KB)
I compared the phase shift between the result of the s-parameter analysis and of the monitor of transmission in the subset of s-parameter anaysis. A problem is that the results show different shape at a wavelength of 1.8 um. The phase shift by s-parameter analysis shows around pi. In contrast, the phase shift by the transmission monitor shows around -2*pi at 1.8um wavelength.
I thought we can obtain a phase shift through transmission monitor directly by compensating a phase shift by background material (i.e. air, substate, and etc.).
Can you explain why we cannot obtain the phase shift by transmission monitor directly?

Thanks.

Hello @kimmh10281,

The S-parameter analysis group performs some advanced calculations to remove the phase contributed by the metasurface from the natural phase change that would be introduced by propagation alone. This is why you need to specify the span and center of the metamaterial. A transmission monitor will not have any information on the expected phase change of the light since it does not have any reference.

Could you clarify what you mean by phase shift from the transmission monitor? It may be possible to use a time monitor to perform this analysis by having a reference and using time monitors.

Let me know if you have any other questions.

Regards,