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Probing Effective Refractive Index in RF Module

Posted Nov 22, 2010, 3:42 a.m. EST RF & Microwave Engineering, Studies & Solvers Version 4.0a 5 Replies

Kevin Shahbazi
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Hi,

I've been working on calculating the effective refractive index of a photonic crystal based on a parametric sweep of a geometric parameter in COMSOL 4-->RF Module-->Mode Analysis. I have tried doing tutorials, asking professors at my university and e-mailing COMSOL support, yet I am still not able to probe the effective refractive index of the geometry as a function of my geometric parameter (layer thickness).

If anyone has any experience with probing variables in COMSOL, or who can help me conduct this sweep, it would be greatly appreciated.

To add an extra level of complexity, if anyone knows how to conduct a two parameter sweep, I would really appreciate this!

Thank you very much.

Kevin Shahbazi
5 Replies Last Post Jul 28, 2012, 4:23 a.m. EDT
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Hello Kevin Shahbazi

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Arian Kirsch
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Posted: 1 decade ago Dec 30, 2010, 6:44 p.m. EST
Dear colleagues,

I have exactly the same problem. I am using Consol 4.0 with the RF module and I cannot get a list with my maximum neff values (I want to get the full, complex neff with the maximum real part for each mode found). I do a geometrical parameter sweep and get a lot of solutions with each a set of neff.
I can guess this is a problem which really many people have, doing work with comsol in optics particularly.

Best regards

Arian
Dear colleagues, I have exactly the same problem. I am using Consol 4.0 with the RF module and I cannot get a list with my maximum neff values (I want to get the full, complex neff with the maximum real part for each mode found). I do a geometrical parameter sweep and get a lot of solutions with each a set of neff. I can guess this is a problem which really many people have, doing work with comsol in optics particularly. Best regards Arian
Alexandros Kapsalis
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Posted: 1 decade ago Jan 10, 2012, 8:14 a.m. EST
Hi,

If you are using V4.2 then a global variable probe exists with a name neff (emw.neff). If you are using a previous version the you can use a probe variable with the expression j*lambda/emw.k0.
Does anyone now how to distinguish probes between different solutions?

Alx
Hi, If you are using V4.2 then a global variable probe exists with a name neff (emw.neff). If you are using a previous version the you can use a probe variable with the expression j*lambda/emw.k0. Does anyone now how to distinguish probes between different solutions? Alx
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 10, 2012, 8:21 a.m. EST
Hi

A probe generates a specific "Data Set - Probe Solution" there you see to which "Data Set - Solution" it points, slightly cumbersome I agree ;)

--
Good luck
Ivar
Hi A probe generates a specific "Data Set - Probe Solution" there you see to which "Data Set - Solution" it points, slightly cumbersome I agree ;) -- Good luck Ivar
Alexandros Kapsalis
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Posted: 1 decade ago Jan 10, 2012, 9:23 a.m. EST
Thanks for that,

Maybe I did not state my problem well. I have trouble getting the probe value of the effective index (neff) out of the same (probably) solution. For example I request more the one modes around an index value. The result of the probe always refers to the mode with the higher effective index.

Any ideas?
Thanks in advance
Thanks for that, Maybe I did not state my problem well. I have trouble getting the probe value of the effective index (neff) out of the same (probably) solution. For example I request more the one modes around an index value. The result of the probe always refers to the mode with the higher effective index. Any ideas? Thanks in advance
Guan Xiaowei
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Posted: 1 decade ago Jul 28, 2012, 4:23 a.m. EDT
Dear Ivar,

I had a problem when I tried to find the bend modes i.e. the effective refractive indexes, in a silicon ring with air as the cladding by using 2D-axisymmetric and RF module->mode analysis. The problem is all the refractive indexes are very small, which were actually supposed to be a little lower than the refractive idex of silicon, 3.435, and with a loss (imaginary) part.

Actually, I have readed some discussion from the Forum, like the one from Hartwig:

www.comsol.com/community/forums/general/thread/24819/

Actually, my problem is the same with his, but I am not sure I have been clear about his proposed answer, like the "per unit length", which can not be found in V4.0a. (may be can be found in V4.2)

In the attachment, please find my .mph file. If any suggestions, you can modify it directly in the file and send me back : gxwhnxcdndx@yahoo.com.cn

Thanks in advance and best regards!

xiaowei



Dear Ivar, I had a problem when I tried to find the bend modes i.e. the effective refractive indexes, in a silicon ring with air as the cladding by using 2D-axisymmetric and RF module->mode analysis. The problem is all the refractive indexes are very small, which were actually supposed to be a little lower than the refractive idex of silicon, 3.435, and with a loss (imaginary) part. Actually, I have readed some discussion from the Forum, like the one from Hartwig: http://www.comsol.com/community/forums/general/thread/24819/ Actually, my problem is the same with his, but I am not sure I have been clear about his proposed answer, like the "per unit length", which can not be found in V4.0a. (may be can be found in V4.2) In the attachment, please find my .mph file. If any suggestions, you can modify it directly in the file and send me back : gxwhnxcdndx@yahoo.com.cn Thanks in advance and best regards! xiaowei

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