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Using 2D symmetry to simulate optical whispering gallery mode

Posted Jan 12, 2011, 7:23 a.m. EST Studies & Solvers Version 3.5a 3 Replies

Tianxun Gong
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Hi, everyone,
I am using 2D symmetry to simulate whispering gallery mode. The structure is an ellipsoid, r=1.4e-5m and z=3e-5m (axial length), covered within a bigger ellipsoid. the refractive index of the innner ellipsoid is 1.7 and the outer one is 1.44. I am using eigenfrequency analyse and searching eigen frequency around 3.98e14. The boundaries are axial symmetry (the straight symmetry line of half ellipse) and PEC (the surface of ellipse) .
In theory, the light should resonance at the surface of the inner ellipsoid, and the energy should focus on the surface. However, in my simulation, the light penetrates the inner surface and goes out to the surface of outter ellipsoid. also the energy become larger around the axial symmetry line, seems light resonances between the outter surface and the symmetry line. Any one know where is wrong?Thanks!
PS: The COMSOL report is attached as PDF file

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3 Replies Last Post Jan 13, 2011, 1:55 a.m. EST
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 12, 2011, 9:51 a.m. EST
Hi

for me it looks like your modes are some higher order standing transverse waves modes from the ellipse, and not really running around along the edge, what I have understood a "whispering" mode is doing.

From the article a few weeks ago, it seemed that one need a notch to force these modes, and with your 1/2 symmetry I do not see the "notch".

Then it's a question of catching the right frequency as there are very many modes possible here

--
Good luck
Ivar
Hi for me it looks like your modes are some higher order standing transverse waves modes from the ellipse, and not really running around along the edge, what I have understood a "whispering" mode is doing. From the article a few weeks ago, it seemed that one need a notch to force these modes, and with your 1/2 symmetry I do not see the "notch". Then it's a question of catching the right frequency as there are very many modes possible here -- Good luck Ivar
Tianxun Gong
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Posted: 1 decade ago Jan 12, 2011, 8:56 p.m. EST
Thanks for your reply, the reason I didn't using a source to force the whispering gallery mode is because the whispering gallery mode property is only depends on the structure itself but not the source. The source can excite some modes but not all the modes can be excited by a source.I want to know for a certain structure, what mode can be supported and what can not. I attached a paper published before, what I do is similar to this paper. I just do not know why in my simulation the energy is concentrate in the symmetry axial? it should concentrate on the surface of the inner ellipsoide. Thanks for your help!
Thanks for your reply, the reason I didn't using a source to force the whispering gallery mode is because the whispering gallery mode property is only depends on the structure itself but not the source. The source can excite some modes but not all the modes can be excited by a source.I want to know for a certain structure, what mode can be supported and what can not. I attached a paper published before, what I do is similar to this paper. I just do not know why in my simulation the energy is concentrate in the symmetry axial? it should concentrate on the surface of the inner ellipsoide. Thanks for your help!
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Jan 13, 2011, 1:55 a.m. EST
Hi

indeed my quick simulation was really just to look for "running modes", and in 1-2hours at most.
Still in your case I believe you are seeing the "standard modes", either due to the symmetry or that you are not at the right frequency

--
Good luck
Ivar
Hi indeed my quick simulation was really just to look for "running modes", and in 1-2hours at most. Still in your case I believe you are seeing the "standard modes", either due to the symmetry or that you are not at the right frequency -- Good luck Ivar

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