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plasmonic waveguide / surface waves

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Hi,
Im still very new to Comsol.
I have worked along the tutorial to build photonic crystals, that works fine. (www.comsol.com/showroom/gallery/143/)

and now i am trying to simulate a simple planar (2D) plasmonic waveguide. I.e. just a slim (0.1µm) metal strip in air.

now what i would like to see is the wave intensity on the metal/air boundary. however what i actually see is the following
img194.imageshack.us/img194/8573/plasmontest.jpg

now as i said, im new to comsol so it could be some basic misconception of my setup that is not working.

could you possibly give me a few pointers of what i need to remember when building a setup like this.

or even better could somebody upload a very simple example that i can use a reference to see what needs to be set up how.

cheers :)

4 Replies Last Post 23 nov. 2010, 05:08 UTC−5

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Posted: 1 decade ago 12 nov. 2010, 05:08 UTC−5
well im starting to get somewhere but i am still uncertain about some aspects of the simulation.

so if we regard the boundaries of my structure here
img838.imageshack.us/img838/8382/boundaries.png

and i excite the boundary 3 with E0=(0 0 1)'
i get the following
img839.imageshack.us/img839/3803/field.png

this is clearly not what i would expect.

what i want to see is the field maxima to be ON the boundary between copper/air not within the metal.

now i am unclear if it is at all correct to excite boundary 3, as this is the metal, but exciting 1 3 and 5 results in a field that is only present in the cladding, which is also not what i want.

so i am in general slightly puzzled as to what i actually want to excite...

as always any help would be much appreciated, cheers :)
well im starting to get somewhere but i am still uncertain about some aspects of the simulation. so if we regard the boundaries of my structure here http://img838.imageshack.us/img838/8382/boundaries.png and i excite the boundary 3 with E0=(0 0 1)' i get the following http://img839.imageshack.us/img839/3803/field.png this is clearly not what i would expect. what i want to see is the field maxima to be ON the boundary between copper/air not within the metal. now i am unclear if it is at all correct to excite boundary 3, as this is the metal, but exciting 1 3 and 5 results in a field that is only present in the cladding, which is also not what i want. so i am in general slightly puzzled as to what i actually want to excite... as always any help would be much appreciated, cheers :)

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Posted: 1 decade ago 15 nov. 2010, 03:25 UTC−5
so nobody can quickly tell me how to excite surface waves?


from CST i know i would use ports, now im playing with those in COMSOL, but so far to no avail...
so nobody can quickly tell me how to excite surface waves? from CST i know i would use ports, now im playing with those in COMSOL, but so far to no avail...

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Posted: 1 decade ago 16 nov. 2010, 05:21 UTC−5
You should know what you want to calculate.
It seems that you are using eigenfrequency module. In COMSOL eignmode or eigenfrequency module do not need to excite a port. For eigenmode calculation, you need to define the wavelength, and it found the eigenmode automatically by effective index.
For eigenfrequency calculation, it is the other way round.
If you want to see the propagation of the wave inside the waveguide, you need to choose the module "harmonic propagation" for V3.5. For V4.0, it corresponds to "frequency domain" after "emw" is choosen.

You should know what you want to calculate. It seems that you are using eigenfrequency module. In COMSOL eignmode or eigenfrequency module do not need to excite a port. For eigenmode calculation, you need to define the wavelength, and it found the eigenmode automatically by effective index. For eigenfrequency calculation, it is the other way round. If you want to see the propagation of the wave inside the waveguide, you need to choose the module "harmonic propagation" for V3.5. For V4.0, it corresponds to "frequency domain" after "emw" is choosen.

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Posted: 1 decade ago 23 nov. 2010, 05:08 UTC−5
yes but that's is exactly what I've tried, i only got to the ports because nothing else was working.

all attempts to excite my structure with a scattering boundary as described in my second post above have been fruitless.
either the field is only in the cladding or only in the core with both not being correct...

i just don't know what else to try and look at...

this is what i would like to see, im not (yet) interested in seeing an animation of the wave propagation a static image of the field intensity would suffice for now...
img201.imageshack.us/img201/1440/unbenanntdzo.png
but as stated above the field intensity is either outside or inside the metal core not on the metal/dielectric boundary...
yes but that's is exactly what I've tried, i only got to the ports because nothing else was working. all attempts to excite my structure with a scattering boundary as described in my second post above have been fruitless. either the field is only in the cladding or only in the core with both not being correct... i just don't know what else to try and look at... this is what i would like to see, im not (yet) interested in seeing an animation of the wave propagation a static image of the field intensity would suffice for now... http://img201.imageshack.us/img201/1440/unbenanntdzo.png but as stated above the field intensity is either outside or inside the metal core not on the metal/dielectric boundary...

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