Hi,
I have been trying to replicate experimental data from plasmonic structures that cause optical rotation. I have been using periodic conditions and linearly polarized light as the input. I then use the farfield calculations to measure the Efarx and Efary in the +z direction. Using these I calculate the ORD and the ellipticity (which is similar to circular dichroism). Now I used this approach earlier with a nanostructure on a glass substrate and working in transmission. I got results close to my experiments. I have recently tried to replicate nano indentations in a gold film and measure the farfield for reflected light. I get mixed results. I am confused about the farfield calculations which comsol says shouldn't work for periodic boundaries. Yet it worked for the transmissive structure. I have been unable to get an explanation on how to select the domains of the farfield calculations. Should the metal structure be included, or only the surrounding region and if the surrounding region only, do you also add the domains all the way to the boundaries? Also how do you choose whether the boundary relative to the domain is inside or outside, im confused on this as well. Any help would be appreciated. If anyone has done periodic metamaterials, I would appreciate advice on the topic.
Dear Affar,
to search the chirality of a periodic structure, the FDTD method is the one that is most suitable. Should calculate the transmittance and reflectance of the structure, then calculate the RCP and LCP.
Thus, we can calculate the chirality if a phase (called deltateta) between RCP and LCP is found for all lambda transmitted.
One can make a verification check with an analyzer if a maximum intensity is detected at the corresponding point.
Thanks, I managed to do that with FDTD software, like MWS. You can also apply stokes in the way I mentioned and it works, I used FEM comsol for that. I think my problem is more with my hybrid nano structures. The calculations take longer and the structure has to be characterized better. FDTD is certainly faster for searching, though since I started modelling more complex structures (gold film with chiral geometry indented into the surface) I have not been able to get a solution. It maybe more because of wrong mesh settings, but I am working with MWS support to sort it out. Thanks for the reply.
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