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Simulation of basic surface plasmons

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Hey. I am new to comsol and this is my first simulation on it. I am trying to simulate surface plasmons on a IMI interface. I am clueless about what boundary conditions to use.
This is what I did in the draw mode
imageshack.us/photo/my-images/51/drawm.png/

R2 and R4 is the dielectric, R3 is metal. R7, R6 and R5 is PMLs
R2 and r4 AND er value of 1. R3 has permittivity of -6
I have done the sub-domain settings right. What I do not get is the boundary conditions. Should the outer edge should be scattering Conditions? What about the inner edges? How do I implement the continuity condition? What other changes are required? Please help
The output I get is this

imageshack.us/photo/my-images/256/outputb.png/

12 Replies Last Post Mar 7, 2012, 10:17 a.m. EST

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Posted: 1 decade ago Feb 16, 2012, 6:01 p.m. EST
Hey

1. For inner boundaries it is automatically continuity.
2. Scattering boundary works usually pretty well for mode solver and outer boundaries in the optical regime (I had good experience with it). You dont even need PML if you use it (in most cases...).

3. Your picture of the solution looks like you might be off with your Mode analysis frequency & the search value for the neff. You can find the setting for this under physics -> scalar variables (you can change to wavelength under physics -> Properties. And the neff you find under solve -> solver parameters.

-Niklas
Hey 1. For inner boundaries it is automatically continuity. 2. Scattering boundary works usually pretty well for mode solver and outer boundaries in the optical regime (I had good experience with it). You dont even need PML if you use it (in most cases...). 3. Your picture of the solution looks like you might be off with your Mode analysis frequency & the search value for the neff. You can find the setting for this under physics -> scalar variables (you can change to wavelength under physics -> Properties. And the neff you find under solve -> solver parameters. -Niklas

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Posted: 1 decade ago Feb 17, 2012, 9:46 p.m. EST
Thank you :) :)
Thank you :) :)

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Posted: 1 decade ago Feb 17, 2012, 9:47 p.m. EST
Sometimes the inner boundary is not automatically taken as continuity. What do I do in such a case?
Sometimes the inner boundary is not automatically taken as continuity. What do I do in such a case?

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Feb 18, 2012, 3:52 a.m. EST
Hi

from my understanding all inner boundaries are ALWAYS taken as continuity, IFF you are within the same physics, AND you are in Geometry "Union" mode.

If not, you might be on the external limit of one physics, in which case a boundary is external boundary for one, and continuity internal for another OR you are in "Assembly" geometry mode. Then ALL COMMON boundaries between grouped objects are dedoubled, and ther is NO default continuity. You must generate the pairs and apply continuity or whatever yourself

Hope I'm clear, this is one of the strengths of COMSOl but often overlooked by many users (applies to 3.5 AND 4 by the way) ;)

--
Good luck
Ivar
Hi from my understanding all inner boundaries are ALWAYS taken as continuity, IFF you are within the same physics, AND you are in Geometry "Union" mode. If not, you might be on the external limit of one physics, in which case a boundary is external boundary for one, and continuity internal for another OR you are in "Assembly" geometry mode. Then ALL COMMON boundaries between grouped objects are dedoubled, and ther is NO default continuity. You must generate the pairs and apply continuity or whatever yourself Hope I'm clear, this is one of the strengths of COMSOl but often overlooked by many users (applies to 3.5 AND 4 by the way) ;) -- Good luck Ivar

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Posted: 1 decade ago Feb 24, 2012, 8:59 a.m. EST
Thank you. There is so much to learn in this software. And I just started. Long way to go before I start getting the hang of it
Thank you. There is so much to learn in this software. And I just started. Long way to go before I start getting the hang of it

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Posted: 1 decade ago Feb 24, 2012, 10:58 p.m. EST
img851.imageshack.us/img851/4912/post0.png

After simulation I got this.. But why is the light entering the dielectric in between. Should it not be like this?
img546.imageshack.us/img546/3599/poog.png



Thank you for the help
http://img851.imageshack.us/img851/4912/post0.png After simulation I got this.. But why is the light entering the dielectric in between. Should it not be like this? http://img546.imageshack.us/img546/3599/poog.png Thank you for the help

Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago Feb 25, 2012, 8:35 a.m. EST
Hi
You should rather upload the images on the forum as not all of us have access to all external load servers

--
Good luck
Ivar
Hi You should rather upload the images on the forum as not all of us have access to all external load servers -- Good luck Ivar

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Posted: 1 decade ago Feb 27, 2012, 5:58 a.m. EST
Sorry.. The Image links are now available. When I try uploading I get an error about incorrect file extension
Sorry.. The Image links are now available. When I try uploading I get an error about incorrect file extension

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Posted: 1 decade ago Feb 27, 2012, 10:02 a.m. EST
Sorry but without more details its hard to figure out what is going on. Could you maybe upload you model (w/o mesh&solution) to the forum?
Then I could take a look at it.
Also even so Comsol Support is sometimes a bit slow, it is always worth sending them an email as well, they are usually pretty helpful.
Sorry but without more details its hard to figure out what is going on. Could you maybe upload you model (w/o mesh&solution) to the forum? Then I could take a look at it. Also even so Comsol Support is sometimes a bit slow, it is always worth sending them an email as well, they are usually pretty helpful.

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Posted: 1 decade ago Mar 5, 2012, 12:57 a.m. EST
i have generated the report for both the simulations.
This is the one given by my professor

www.mediafire.com/?tk4aqul5yt4ey9e

This is the one that I tried to simulate
www.mediafire.com/?a5h3js03u6gpy8q

I want to know why the light penetrates the dielectric surface when the plasmons are supposed to travel at the interface alone
i have generated the report for both the simulations. This is the one given by my professor http://www.mediafire.com/?tk4aqul5yt4ey9e This is the one that I tried to simulate http://www.mediafire.com/?a5h3js03u6gpy8q I want to know why the light penetrates the dielectric surface when the plasmons are supposed to travel at the interface alone

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Posted: 1 decade ago Mar 5, 2012, 10:37 a.m. EST
Hey

1. Could you please use the upload function of this forum? And not upload the files somewhere else?

2. Instead of using the report, could you just upload the .mph file itself? (Clear Mesh & Solutions)

-Niklas
Hey 1. Could you please use the upload function of this forum? And not upload the files somewhere else? 2. Instead of using the report, could you just upload the .mph file itself? (Clear Mesh & Solutions) -Niklas

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Posted: 1 decade ago Mar 7, 2012, 10:17 a.m. EST
Not sure I can not see your post in here, but I got an email with it. Anyways, I played around a bit with the model you gave me:

1. Mesh finer (refine mesh 1-2 times)
2. At the same time reduce the size of the simulation domain where you do not need it.
3. I am not sure about your scales, but from my feeling you dimensions with respect to the wavelength are off. The wavelength should be larger or the dimensions smaller, not sure what you are trying to do with this model? Is this a real physical system you are trying to model?

Doing this, I get some results (see file in the attachment).

Let me know if this is what you are looking for?

Also it seems the file problems you were having were related to firefox? I just had a similar problem, where attaching a file did not work with firefox, but the same file was okay with internet explorer....
Not sure I can not see your post in here, but I got an email with it. Anyways, I played around a bit with the model you gave me: 1. Mesh finer (refine mesh 1-2 times) 2. At the same time reduce the size of the simulation domain where you do not need it. 3. I am not sure about your scales, but from my feeling you dimensions with respect to the wavelength are off. The wavelength should be larger or the dimensions smaller, not sure what you are trying to do with this model? Is this a real physical system you are trying to model? Doing this, I get some results (see file in the attachment). Let me know if this is what you are looking for? Also it seems the file problems you were having were related to firefox? I just had a similar problem, where attaching a file did not work with firefox, but the same file was okay with internet explorer....

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