Learning Forum

[Myunghwan]

Hi.nI?m calculating phase delay by metasurfaces.nThe output phase can be calculated using S-parameter analysis group for s or p polarization sources.nHow can I calculate output phase (s-parameters) when a circular polarization source is launched?nThe S-parameter analysis group supports only s and p polarization source.nThanks.n

[Guilin Sun]

A simple method to calculate S parameter is to get both s/p component and recombine them into one single S similar to the circular polarization. You can modify the analysis group to pick up two field components instead of the built-in single component.nHowever, since the max magnitude of S is 1, but Ex, Ey (suppose propagating along z) may have larger than 1 value So you may need to normalize it. nA more complicated method might be to get S from its definition by involving E and H, which is out of this forum scope.nn

[Guilin Sun]

Please note that for each element of the metasurface, it is meaningful to have their S parameters to quantify its magnitude and phase. For the whole metasurface which transforms a incident plane wave into a focused beam, it might be not meaningful, as the focused beam is not a stationary mode such as a mode in waveguide, nor a plane wave with giving propagation direction with a magnitude and phase. S parameters are used to quantify a system's performance: https://support.lumerical.com/hc/en-us/articles/360042095873-Metamaterial-S-parameter-extraction Usually the S parameters will not be space-location dependent, meaning they are not a function of space. Please think it carefully.n