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PML for infinite layered films

Posted Mar 21, 2013, 1:55 p.m. EDT RF & Microwave Engineering Version 4.3, Version 4.3a, Version 4.4, Version 5.0 7 Replies

Leiming Wang
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Dear folks,

I am trying to simulate a point source illuminating on a stacked films extending to infinite. A intuitive way to truncate the film, I think, is to use PML. However, when extending the layered film material into PML, the performance of PML obviously is not good, even worse than Scattering BC without PML. I attached a figure showing the field, compared to a FDTD result, reflection from the PML boundary is apparent. COMSOL technique support also indicates that PML does not work well for infinite films, and suggests to live with SBC. So I am wondering is anyone here has encountered similar problem and can share the experience. Thanks a lot.

Best Regards,
Leiming
7 Replies Last Post Dec 20, 2014, 10:20 p.m. EST
Alexander Kuznetsov
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Posted: 1 decade ago Mar 21, 2013, 2:26 p.m. EDT

However, when extending the layered film material into PML, the performance of PML obviously is not good, even worse than Scattering BC without PML.


I do it all the time and the performance is very good. I see virtually no reflection from PML's inner boundaries within ~10^(-6) precision. Try playing with PML's options.

By the way, make sure to use same material properties for PML as for the corresponding films.
[QUOTE] However, when extending the layered film material into PML, the performance of PML obviously is not good, even worse than Scattering BC without PML. [/QUOTE] I do it all the time and the performance is very good. I see virtually no reflection from PML's inner boundaries within ~10^(-6) precision. Try playing with PML's options. By the way, make sure to use same material properties for PML as for the corresponding films.
Leiming Wang
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Posted: 1 decade ago Mar 21, 2013, 2:45 p.m. EDT
Dear Alexander,

Your comment is highly appreciated. I am very glad to learn that it is indeed possible to improve it by fine tuning the PML settings, which is also the purpose I am seeking help here.
Yes, I did use same material for the inner domain and the PML for corresponding layers. BTW, there is a metal film among the layers.
I am using Comsol v4.3a, the only parameters I saw for tuning the PML setting are PML scaling factor and scaling curvature. FEA is kind new to me, I randomly tried different values for these two, but not successful. Could you please help explain a bit more detail of, e.g. the general strategies for tuning the PML parameters,if there are. If you allow, I can send in my test model.

Thank you very much,

Leiming
Dear Alexander, Your comment is highly appreciated. I am very glad to learn that it is indeed possible to improve it by fine tuning the PML settings, which is also the purpose I am seeking help here. Yes, I did use same material for the inner domain and the PML for corresponding layers. BTW, there is a metal film among the layers. I am using Comsol v4.3a, the only parameters I saw for tuning the PML setting are PML scaling factor and scaling curvature. FEA is kind new to me, I randomly tried different values for these two, but not successful. Could you please help explain a bit more detail of, e.g. the general strategies for tuning the PML parameters,if there are. If you allow, I can send in my test model. Thank you very much, Leiming
Alexander Kuznetsov
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Posted: 1 decade ago Mar 21, 2013, 5:05 p.m. EDT
You can upload your model here
You can upload your model here
Leiming Wang
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Posted: 1 decade ago Mar 21, 2013, 6:07 p.m. EDT

You can upload your model here


Many thanks, Alex, uploaded.
Any insight you may offer is highly appreciated.

Leiming
[QUOTE] You can upload your model here [/QUOTE] Many thanks, Alex, uploaded. Any insight you may offer is highly appreciated. Leiming

Attachments:

Alexander Kuznetsov
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Posted: 1 decade ago Mar 21, 2013, 7:03 p.m. EDT
Sorry, can't open it because of version mismatch. I got 4.3 version
Sorry, can't open it because of version mismatch. I got 4.3 version
Leiming Wang
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Posted: 1 decade ago Mar 21, 2013, 7:28 p.m. EDT
No problem, that's true, COMSOL is not forward-compatible.
Anyway, thanks for discussion. See if other experts may be able to offer some help.

Regards,
Leiming
No problem, that's true, COMSOL is not forward-compatible. Anyway, thanks for discussion. See if other experts may be able to offer some help. Regards, Leiming
WEI WANG
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Posted: 1 decade ago Dec 20, 2014, 10:20 p.m. EST
Dear Alexander Kuznetsov,

I also have the same problem, can you upload your file to show how to fine tune the PML boundary condition? thanks
Dear Alexander Kuznetsov, I also have the same problem, can you upload your file to show how to fine tune the PML boundary condition? thanks

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