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photonic crystal fiber

Posted Jan 14, 2012, 10:03 a.m. EST RF & Microwave Engineering Version 4.1, Version 4.3b, Version 4.4 22 Replies

Sahin Khan
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Hi,

I am a beginner of comsol v 4. I tried to design a pcf with hexagonal pattern of airholes (five rings).
pitch=2um and d=1 um.
I got real part of effective mode index but don't get any imaginary part. Why?
The dispersion curve was not so good. Please help me.
22 Replies Last Post Dec 29, 2016, 12:55 p.m. EST
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Deepak Jain
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Posted: 1 decade ago Feb 17, 2012, 8:56 a.m. EST
Hi,

can you please show me your .mph file then I can comment.
Hi, can you please show me your .mph file then I can comment.
Tee Din Chai
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Posted: 1 decade ago Mar 16, 2012, 11:00 a.m. EDT
i am facing the same problem too..

do you know how to solve it?
teach me, pls.
thx
i am facing the same problem too.. do you know how to solve it? teach me, pls. thx
Deepak Jain
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Posted: 1 decade ago Mar 16, 2012, 1:42 p.m. EDT
Show me your mph file only then I can comment.
Show me your mph file only then I can comment.
Tee Din Chai
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Posted: 1 decade ago Mar 16, 2012, 10:20 p.m. EDT
i dont know why i cant attach my file, maybe because it is too large, is around 15Mb.
i dont know why i cant attach my file, maybe because it is too large, is around 15Mb.
Deepak Jain
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Posted: 1 decade ago Mar 17, 2012, 5:07 a.m. EDT
You have to use PML layer to calculate the imaginary part. Or might be your mesh is not good enough. You just send me the geometry without meshing it. Its difficult diagnose a problem this way.
You have to use PML layer to calculate the imaginary part. Or might be your mesh is not good enough. You just send me the geometry without meshing it. Its difficult diagnose a problem this way.
Tee Din Chai
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Posted: 1 decade ago Mar 17, 2012, 5:22 a.m. EDT
will send it to you once i back to my lab tml.
my structure is without any PML, i use PEC outside my structure.

by the way, why i must use PML to calculate the imag part?
since my material properties (exap : refractive index is real value) and all other parameters are also real value,
so, from a System of pure real value, how i can get imaginary solution?

what you mean by mesh is not good enough? mesh size too small or too huge?

thx
will send it to you once i back to my lab tml. my structure is without any PML, i use PEC outside my structure. by the way, why i must use PML to calculate the imag part? since my material properties (exap : refractive index is real value) and all other parameters are also real value, so, from a System of pure real value, how i can get imaginary solution? what you mean by mesh is not good enough? mesh size too small or too huge? thx
Delwar
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Posted: 1 decade ago Mar 17, 2012, 5:49 a.m. EDT
Hello,
I think you can attach the Comsol Model. If you clear the solution and meshes(go to edit menu, clear solution and mesh), then the size of model will be reduced and save it.

Regards
D Bhuyan
Hello, I think you can attach the Comsol Model. If you clear the solution and meshes(go to edit menu, clear solution and mesh), then the size of model will be reduced and save it. Regards D Bhuyan
Tee Din Chai
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Posted: 1 decade ago Mar 17, 2012, 11:35 p.m. EDT
hi Deepak Jain,

i attached the mph file.
have a look and give me some comment.
thx
hi Deepak Jain, i attached the mph file. have a look and give me some comment. thx

Attachments:

Tee Din Chai
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Posted: 1 decade ago Mar 17, 2012, 11:35 p.m. EDT
Delwar Bhuyan,

thx for the sharing......
Delwar Bhuyan, thx for the sharing......
Deepak Jain
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Posted: 1 decade ago Mar 22, 2012, 3:48 a.m. EDT
Hi Tee,

Sorry for late replying. I was fairly busy over last week. yes I have given a look to your proble. you should have used PML. Go to Electromagnetic waves right click you will find PML. you asked why is it necessary. it is necessary to compute confinement loss from fibre the light that is being absorbed by PML. You can read about PML. there is plenty of papers search on internet. Hope this is clear.
Hi Tee, Sorry for late replying. I was fairly busy over last week. yes I have given a look to your proble. you should have used PML. Go to Electromagnetic waves right click you will find PML. you asked why is it necessary. it is necessary to compute confinement loss from fibre the light that is being absorbed by PML. You can read about PML. there is plenty of papers search on internet. Hope this is clear.
Tee Din Chai
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Posted: 1 decade ago Mar 22, 2012, 5:13 a.m. EDT
there are some PML types, i think i will choose cylindrical.
by the way, if i want to insert my own equation for the PML, is it possible?
because i read some simulation journal, they mentioned about the equation they used for PML.

thx
there are some PML types, i think i will choose cylindrical. by the way, if i want to insert my own equation for the PML, is it possible? because i read some simulation journal, they mentioned about the equation they used for PML. thx
Deepak Jain
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Posted: 1 decade ago Mar 22, 2012, 5:27 a.m. EDT
Hi Tee,

u have to use cylindrical in this case. u can also use cartesian one if u use square str fr ur pml. Regarding equation do not worry at this moment. It is already implemented in comsol. U have to check subnode of pml, in which u have to chose option refractive index in this case rather than permittivity. this is a small issue but not corrected can give you error.
Hi Tee, u have to use cylindrical in this case. u can also use cartesian one if u use square str fr ur pml. Regarding equation do not worry at this moment. It is already implemented in comsol. U have to check subnode of pml, in which u have to chose option refractive index in this case rather than permittivity. this is a small issue but not corrected can give you error.
Tee Din Chai
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Posted: 1 decade ago Mar 22, 2012, 10:34 a.m. EDT
Thanks for the information..
Hv you try to calculate the dispersion for PCF?
i wonder why my dispersion curve is shifted upward when i compared it with the result reported in journal.
Thanks for the information.. Hv you try to calculate the dispersion for PCF? i wonder why my dispersion curve is shifted upward when i compared it with the result reported in journal.
Haris Saja
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Posted: 1 decade ago Jun 4, 2012, 3:01 a.m. EDT
Hi Deepak,

I tried to use PML in my PCF model by using COMSOL 4.1, but there is an error and I don't know how to solve this error. Would you like help me to find the solution of this problem? I attach my PCF file here.

Thank's a lot
Haris
Hi Deepak, I tried to use PML in my PCF model by using COMSOL 4.1, but there is an error and I don't know how to solve this error. Would you like help me to find the solution of this problem? I attach my PCF file here. Thank's a lot Haris
S Felix
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Posted: 1 decade ago Jun 12, 2012, 3:07 a.m. EDT
Hi Haris Saja,

I guess you will need to do the following:
1) Go to;
Model builder-------->> Materials; Here you need to select material type for your PML (domains 1,2,3,4,7,8,9) to be either Air or Silica. For the choice you can refer several discussions here on the forum.

2) Go to;
Model builder-------->> Electromagnetic waves------->> perfect matched layers------>> Wave equation, electric1;
Look at settings window (right hand side) under "electric displacement field" model and choose "refractive index" from the drop down list.

I hope this will solve your problem.

all the best





Hi Deepak,

I tried to use PML in my PCF model by using COMSOL 4.1, but there is an error and I don't know how to solve this error. Would you like help me to find the solution of this problem? I attach my PCF file here.

Thank's a lot
Haris


Hi Haris Saja, I guess you will need to do the following: 1) Go to; Model builder-------->> Materials; Here you need to select material type for your PML (domains 1,2,3,4,7,8,9) to be either Air or Silica. For the choice you can refer several discussions here on the forum. 2) Go to; Model builder-------->> Electromagnetic waves------->> perfect matched layers------>> Wave equation, electric1; Look at settings window (right hand side) under "electric displacement field" model and choose "refractive index" from the drop down list. I hope this will solve your problem. all the best [QUOTE] Hi Deepak, I tried to use PML in my PCF model by using COMSOL 4.1, but there is an error and I don't know how to solve this error. Would you like help me to find the solution of this problem? I attach my PCF file here. Thank's a lot Haris [/QUOTE]
Haris Saja
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Posted: 1 decade ago Jun 14, 2012, 3:29 a.m. EDT
Hi Felix,

Thank's for your explanation.. :)
Hi Felix, Thank's for your explanation.. :)
Polepalli Siva Krishna
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Posted: 1 decade ago Dec 6, 2013, 1:37 a.m. EST
i am new to comsol, i am trying to use pml in my pcf, can any one tell me hw to use
i am new to comsol, i am trying to use pml in my pcf, can any one tell me hw to use
Tee Din Chai
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Posted: 1 decade ago Dec 6, 2013, 1:46 a.m. EST
Polepalli,

You can just use the built-in PML. (or you can define your own PML equation, you can find it from internet)

Just draw another domain (cylindrical or rectangular) surrounding the outer boundary of your PCF. You have to define the material for that domain too, and select that domain as your PML.

Polepalli, You can just use the built-in PML. (or you can define your own PML equation, you can find it from internet) Just draw another domain (cylindrical or rectangular) surrounding the outer boundary of your PCF. You have to define the material for that domain too, and select that domain as your PML.
Polepalli Siva Krishna
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Posted: 1 decade ago Dec 6, 2013, 5:59 a.m. EST
what type of material can i choose for that domain
what type of material can i choose for that domain
Tee Din Chai
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Posted: 1 decade ago Dec 6, 2013, 6:25 a.m. EST
Normally it is the same material as your PCF. Because you are truncating your PCF with the PML..
Normally it is the same material as your PCF. Because you are truncating your PCF with the PML..
Ouadah Chemss Eddine
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Posted: 1 decade ago Apr 23, 2014, 6:25 a.m. EDT
Hello Sir,please what is the material of pml can me use for pcf fibers
Hello Sir,please what is the material of pml can me use for pcf fibers
Fairuz Nova
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Posted: 8 years ago Dec 29, 2016, 12:55 p.m. EST
Can you post your code for plotting dispersion curve ? I need that badly
Can you post your code for plotting dispersion curve ? I need that badly

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