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How to measure power in COMSOL wave optics?

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Hi all,

I'm wondering if anyone knows how to measure the power in COMSOL wave optics, for example the power coming out of from a line in a case of 2D simulation.

I've seen in a video on Youtube where the lecturer integrated the 'sqrt(ewfd.Poavx^2+ewfd.Poavy^2+ewfd.Poavz^2)' value along a line to represent the power. However, the software also provides a value called 'ewfd.nPoav'. I'm confused which one is the correct one to use since they sometimes actually give different results. I tried to test these two methods by checking, for example, the power at the input side and output side of a slab waveguide, but the power I measured at the input and the output do not agree with each other. Does anyone know the correct way to measure the power? Many thanks in advance.


1 Reply Last Post Oct 19, 2017, 9:44 p.m. EDT
Robert Koslover Certified Consultant

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Posted: 6 years ago Oct 19, 2017, 9:44 p.m. EDT

The ewfd.nPoav variable refers to the component of the average power that is "normal" to (aka, perpendicular to) a particular surface. It is thus not the same as the "norm" or magnitude, of the vector, in general. This is why you get a different answer from using the longer expression.

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Scientific Applications & Research Associates (SARA) Inc.
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The ewfd.nPoav variable refers to the component of the average power that is "normal" to (aka, perpendicular to) a particular surface. It is thus not the same as the "norm" or magnitude, of the vector, in general. This is why you get a different answer from using the longer expression.

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