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Help Modeling Au Nanoparticle Plasmonic Resonance

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Hi, I'm a new Comsol user and am trying to simulate the transmission spectra of a gold nanoparticle, and I'm getting some confusing results. I based the model of of the "plasmonic wire grating" example model, and while the electric field distribution results make sense, and show well localized plasmonic modes at different corners of the particle, the transmission spectra doesn't show any obvious plasmonic resonances.

Maybe I'm confused with how to define the transmission coefficient. Currently I'm defining the transmission coefficient as abs(emw.S21)^2 where port 1 is where the plane wave is excited and port 2 is where it is terminated. In the attached screenshot I've shown where the scattering matrix element for port 2 is defined in the port settings->equation tab. This expression makes it seem like only the light that is in the same direction as the incident light is counted towards the transmission spectrum, which seems strange to me as light could be scattered in any direction.

Could someone A) explain how to interpret the scattering matrix element in the attached screenshot and B) give any insight into how to properly set up the physics (ports, boundary conditions, meshing) so that a proper transmission spectrum can be attained?

Thanks for any help!


0 Replies Last Post Feb 18, 2015, 5:47 p.m. EST
COMSOL Moderator

Hello Ryan Freeman

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