Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Electric field distribution - Point Source
Posted 2013年11月18日 GMT-5 22:00 RF & Microwave Engineering, Materials, Studies & Solvers Version 4.2, Version 4.2a, Version 4.3, Version 4.3a, Version 4.3b 3 Replies
Please login with a confirmed email address before reporting spam
I want to simulate the Vertical and Horizontal polarization of dipole source.
Its Au-GaAs-Air structure with electric dipole source. You can find that in attachment. For this we need to import n and k values for both GaAs and Gold right ? I did it and imported via interpolation. Since I m dealing in Lambda I made arguments in nm. The data source file for GaAs and Au can be found in mph file. I got that from refractive index.info site. I think for each wavelength, the values are not listed.So this would be fine for simulation?? And I had defined the relative permittivity in GaAs and Au. Is thats right ?? Can we use Scat B.C or PML for this ?
For Vertical and Horizontal Polarization, I chose Dipole : Magnitude and direction - x = 0 and y=1 for V-Pol and vice versa for H-Pol right ? Correct me if I m wrong.
Thank you.
Its Au-GaAs-Air structure with electric dipole source. You can find that in attachment. For this we need to import n and k values for both GaAs and Gold right ? I did it and imported via interpolation. Since I m dealing in Lambda I made arguments in nm. The data source file for GaAs and Au can be found in mph file. I got that from refractive index.info site. I think for each wavelength, the values are not listed.So this would be fine for simulation?? And I had defined the relative permittivity in GaAs and Au. Is thats right ?? Can we use Scat B.C or PML for this ?
For Vertical and Horizontal Polarization, I chose Dipole : Magnitude and direction - x = 0 and y=1 for V-Pol and vice versa for H-Pol right ? Correct me if I m wrong.
Thank you.
Attachments:
3 Replies Last Post 2013年11月21日 GMT-5 08:35
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
First, a few comments on the model. You may want to consider Impedance BCs instead of modeling the entire gold structure. The IBC should still accurately account for the loss into the metal, and your model size is nearly cut in half. Test it out! Also, you will not want to eliminate the PML on the air boundary--air boundaries will not act like a scattering boundary.
Second, it looks like the material properties are properly set: the indexes (and thus the permittivities) are functions of "lambda" and this is the variable you are parametrizing. You can check if you have done it properly by selecting the interpolation and hitting "plot", and look at the associated curve on RefractiveIndex.Info site. You ask " I think for each wavelength, the values are not listed.So this would be fine for simulation??" This is precisely what the interpolation has done for you--converted discrete data points (from published data) into a continuous curve that can be sampled for ANY wavelength in that range!
Now, back to the dipole. Yes, you can control the polarization in the manner in which you state. You could even place multiple dipoles of various magnitudes and directions on top of each other to simulate coherent, unpolarized emission (I think there is a laborious way to do incoherent emission). However, the question remains as to what kind of data you would like to retrieve. You mention "finding electric field with Point source will be easy using COMSOL"--you are correct, it is! Just place the boundary/point probe where you want to sample (average, integrate, etc.) the field generated (and scattered) from the point source. But so what? Is the full-field output all the information you need? You will not get a transmittance that way! You won't even isolate the scattered field that way. So what is it you WANT to get out of the simulation?
-----------------------------------------------------------------------------------------------------------------------------------------------------------
Hi Bryan
Thank you so much for explanations. I think posting here will be more relevant.
First I clarify that with this simulation not interested in Transmission/Spectral Transmittance.
With Polarization(Horizontal mainly) in Dipole source, I want to find suitable position for Dipole (Point source between Au and Point source (QD). SO with this simulation, I m going to check the node and anti-node with respect to each target wavelength. For each target wavelength, I need either node/anti-node with respect to QD position. (for idea i just attached a picture). So based on QD position the desired target is achieved.
How about using SBC ? I tried with SBC and it looks better. Or IBC will be best for this ??
Second, it looks like the material properties are properly set: the indexes (and thus the permittivities) are functions of "lambda" and this is the variable you are parametrizing. You can check if you have done it properly by selecting the interpolation and hitting "plot", and look at the associated curve on RefractiveIndex.Info site. You ask " I think for each wavelength, the values are not listed.So this would be fine for simulation??" This is precisely what the interpolation has done for you--converted discrete data points (from published data) into a continuous curve that can be sampled for ANY wavelength in that range!
Now, back to the dipole. Yes, you can control the polarization in the manner in which you state. You could even place multiple dipoles of various magnitudes and directions on top of each other to simulate coherent, unpolarized emission (I think there is a laborious way to do incoherent emission). However, the question remains as to what kind of data you would like to retrieve. You mention "finding electric field with Point source will be easy using COMSOL"--you are correct, it is! Just place the boundary/point probe where you want to sample (average, integrate, etc.) the field generated (and scattered) from the point source. But so what? Is the full-field output all the information you need? You will not get a transmittance that way! You won't even isolate the scattered field that way. So what is it you WANT to get out of the simulation?
-----------------------------------------------------------------------------------------------------------------------------------------------------------
Hi Bryan
Thank you so much for explanations. I think posting here will be more relevant.
First I clarify that with this simulation not interested in Transmission/Spectral Transmittance.
With Polarization(Horizontal mainly) in Dipole source, I want to find suitable position for Dipole (Point source between Au and Point source (QD). SO with this simulation, I m going to check the node and anti-node with respect to each target wavelength. For each target wavelength, I need either node/anti-node with respect to QD position. (for idea i just attached a picture). So based on QD position the desired target is achieved.
How about using SBC ? I tried with SBC and it looks better. Or IBC will be best for this ??
Attachments:
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Ah, yes--I think I see what you are trying to do, now.
Keep in mind SBC will get you results of just the dipole radiation, since all the scattering inside the cavity will be suppressed (as will the portion of the dipole radiation that is parallel to the boundary--but at this proximity, that should be negligible). This seems to be what you want. Do you care about what the true (full) field will be? If so, then use the IBC. Certainly the results will be vastly different for the IBC compared to the SBC, because of the inclusion of the high scattering effects.
As a second thought, have you considered any modal studies? I am not sure if it is possible with the open air boundary (I've never tried this), but it might be worth a look. If it works, it would certainly save you time, rather than scanning over a broad range looking for the right frequencies that produce nodes at the boundaries. Maybe someone else could chime in if they have ever done this.
Keep in mind SBC will get you results of just the dipole radiation, since all the scattering inside the cavity will be suppressed (as will the portion of the dipole radiation that is parallel to the boundary--but at this proximity, that should be negligible). This seems to be what you want. Do you care about what the true (full) field will be? If so, then use the IBC. Certainly the results will be vastly different for the IBC compared to the SBC, because of the inclusion of the high scattering effects.
As a second thought, have you considered any modal studies? I am not sure if it is possible with the open air boundary (I've never tried this), but it might be worth a look. If it works, it would certainly save you time, rather than scanning over a broad range looking for the right frequencies that produce nodes at the boundaries. Maybe someone else could chime in if they have ever done this.
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Currently interested in finding node and antinode positions. After discussing my results with my Prof, then i will step up further what to do. In case if there is need of (true) full field, I will check with IBC conditions.
As for the modal studies, with my structure I should consider Air region. Anyways I have to discuss with my prof if its necessary to do. But I will check with this study.
And really thanks Bryan for your support and comments along with model examples u did for me. It really helped a lot. Hope I will get your support in any of my next discussions.
As for the modal studies, with my structure I should consider Air region. Anyways I have to discuss with my prof if its necessary to do. But I will check with this study.
And really thanks Bryan for your support and comments along with model examples u did for me. It really helped a lot. Hope I will get your support in any of my next discussions.