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Farfield light scattering

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Hello,

I'm using COMSOL Multiphysics 5.5 to calculate light scattering by a nanolens (50 nm of radius). I have a detector, which integrated power flow over a certain surface area, far from the nanolens (a few mm far). The incident beam is expressed via plane wave expansion method in electromagnetic waves, frequency domain, ewfd (660 nm wavelength and 400 nm beam waist, so "port" is not usable). Therefore, it's similar to an antenna example, but with an incident beam. I found two ways for this kind of problems: 1. Farfield calcualtion and 2. electromagnetic waves, beam envelopes, ewbe.

My question is: 1. With the Farfild calcualtion, how do I calculate the power flow? I can calculate the power flow from the background electric field (Eb) and near scattered field (Erel), but how do I find the power flow from the farfield scattering amplitude (Efar) and interference between the farfield and the background field? It seems that only I can get is the scattering amplitude, but does it need some normalization? then how?

  1. When I use the ewfd to calculate the scattering and the ewbe to find the power flow far from the scatterer, can I express the beam with PWEM and use the Scattered-field calculation, instead of port and Full-field calculation? All examples I found use the Full-field formalism, so I'm not sure about it.

0 Replies Last Post 29 mars 2021, 18:43 UTC−4
COMSOL Moderator

Hello Suhun Jo

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