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about transmission/reflection coefficients of a nano grating

Posted Apr 11, 2012, 11:16 a.m. EDT RF & Microwave Engineering Version 4.2a 6 Replies

Hongtao Zhang
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Hello,

This question is related to my old message (www.comsol.com/community/forums/general/thread/27434/)
It is about a calculation of transmission/reflection coefficients of a nano grating. I list the problem description and code at the attachment.

After modifying some parameters, I can plot the curve of Transmission/Reflection coefficients in COMSOL. However, there exist several unnecessary oscillations in the curve, which also depends on the grid size. This calculation is not correct and contracts with our known analytic results.

In addition, this mode is related to anomaly effect of grating. I notice from this forum that there may be some problem in calcuation by COMSOL. I am confusing by where the problem comes from. Any suggestion is welcome.

Thanks.

Hongtao
6 Replies Last Post Apr 12, 2012, 7:08 a.m. EDT
Alexander Kuznetsov
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Posted: 1 decade ago Apr 11, 2012, 1:05 p.m. EDT
your top and bottom domains are way too large. With you default mesh you don't have enough mesh elements per wavelength. Maximum element size 150 nm with lambda 600 nm is not enough, especially for oblique angles.
your top and bottom domains are way too large. With you default mesh you don't have enough mesh elements per wavelength. Maximum element size 150 nm with lambda 600 nm is not enough, especially for oblique angles.
Hongtao Zhang
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Posted: 1 decade ago Apr 11, 2012, 3:41 p.m. EDT
Thanks you, Alexander!

I will modify this distance and re-do the calculation. WIll discuss with you later.


Hongtao


your top and bottom domains are way too large. With you default mesh you don't have enough mesh elements per wavelength. Maximum element size 150 nm with lambda 600 nm is not enough, especially for oblique angles.




Thanks you, Alexander! I will modify this distance and re-do the calculation. WIll discuss with you later. Hongtao [QUOTE] your top and bottom domains are way too large. With you default mesh you don't have enough mesh elements per wavelength. Maximum element size 150 nm with lambda 600 nm is not enough, especially for oblique angles. [/QUOTE]
Qiao Ma
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Posted: 1 decade ago Apr 11, 2012, 5:42 p.m. EDT
I was always stuck with the same problems, there exists some resonance peak in small wavelength range (www.comsol.com/community/forums/general/thread/27642/#p75220).

Regards!
I was always stuck with the same problems, there exists some resonance peak in small wavelength range (http://www.comsol.com/community/forums/general/thread/27642/#p75220). Regards!
Hongtao Zhang
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Posted: 1 decade ago Apr 11, 2012, 7:15 p.m. EDT
yeah, that is what I am figuring out. The resonance peak should only be one for the thin film.

I did not know why I have so many peaks.

By the way, Qian, could you send me your code if feasiable by my email address: hzhang2012@gmail.com.
We can discuss this problem.

Hongtao
yeah, that is what I am figuring out. The resonance peak should only be one for the thin film. I did not know why I have so many peaks. By the way, Qian, could you send me your code if feasiable by my email address: hzhang2012@gmail.com. We can discuss this problem. Hongtao
Qiao Ma
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Posted: 1 decade ago Apr 12, 2012, 3:30 a.m. EDT
Sure, I will send my code to you.

Sure, I will send my code to you.
Qiao Ma
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Posted: 1 decade ago Apr 12, 2012, 7:08 a.m. EDT
I have sent the code to you!
Please check your email!
Looking forward to discussing with you!

Regards!
I have sent the code to you! Please check your email! Looking forward to discussing with you! Regards!

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