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one question on the 1-D plot for global for nano-grating

Posted Mar 30, 2012, 10:43 a.m. EDT 2 Replies

Hongtao Zhang
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Hello,

I have one question on the 1-D plot.

The question is to investigate the property of nano-grating by COMSOL 4.2a. The model is to calculate the reflection and transmission of a 2D infinite long plane with periodic shallow notches. This structure is regarded a grating. Polarized plane light wave comes from top to down with an incident angle α. The complete problem and mph file are attached in this messge.

I guess I get a correct 2D picture but when I plot the graph, it shows us "Empty expression, -Plot globa1 (Global).


Could you help check this error?

Thanks.

Hongtao



2 Replies Last Post Mar 30, 2012, 1:21 p.m. EDT
Alexander Kuznetsov
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Posted: 1 decade ago Mar 30, 2012, 12:38 p.m. EDT
It gives this error because it can't properly solve the problem for non-zero angle. The thing is that your geometry is wrong. You are defining periodic BC on the boundaries which are different. Boundary on the left has the notch while boundary on the right doesn't. The proper way to make your structure would be to shift it by Period/4. For example, you can have your trench in the middle and the notch on both sides of it.
It gives this error because it can't properly solve the problem for non-zero angle. The thing is that your geometry is wrong. You are defining periodic BC on the boundaries which are different. Boundary on the left has the notch while boundary on the right doesn't. The proper way to make your structure would be to shift it by Period/4. For example, you can have your trench in the middle and the notch on both sides of it.
Hongtao Zhang
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Posted: 1 decade ago Mar 30, 2012, 1:21 p.m. EDT
Thanks. Let me try modifying the model. I will tell you the calculation later.

Hongtao
Thanks. Let me try modifying the model. I will tell you the calculation later. Hongtao

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