Polarization conversion

Hello all;

I’m trying to simulate the polarization conversion. I tried the example submitted by Lumerical but it doesn’t work and the script gives error when running analysis. I want to know where is the problem and also to know if this is the correct way to find the polarization conversion of graphene structures.

This is example of Lumerical
usr_pol_ellipse.fsp (356.3 KB)

Thanks in advance

I was able to run the analysis script without any errors using the latest version of FDTD Solutions. If you are not using the latest version, you might want to upgrade. You can download the latest version from here:

Could you let me know what is the error message that you see when you try to run the analysis?

This group could be used with periodic graphene structures to find the polarization of transmitted light.

Hi nlui;
Thank you for your response and sorry for being late to interact.
I tried the latest version and it works, thanks again.
I try to validate this paper
graphene-optics express.pdf (3.8 MB)

The structure is
gsquare

and the results
PCR

My data suffer alternating points like this:

  1. I am confused about importing the gold data (carrier concentration and scattering time), I assumed the plasma resonance is 2.1106e+010 without scattering.

This is my file
https://drive.google.com/a/aucegypt.edu/file/d/0BzBSPwM64h0VdzQ3T0JabDhicU0/view?usp=sharing

Thanks for help

Hi,

Unfortunately I wasn’t able to access your file. The file sharing permissions may need to be modified.

Regarding the question about modelling gold, you can use the Plasma material model to model a Drude material. Information about the Plasma model is here:
https://kb.lumerical.com/en/index.html?materials_permittivity_models.html

This model takes the plasma resonance and the scattering rate in units of rad/s. The scattering rate is 2*pi/scattering time and the the carrier concentration can be related to the plasma resonance using the equations on page 3 of the following:

Thanks nlui
I re-send the file, I hope you find it or open the link:
https://drive.google.com/a/aucegypt.edu/file/d/0BzBSPwM64h0Va1lYcXl0aUo3cjQ/view?usp=sharing

thanks

Unfortunately I still receive a message that I do not have permission to access the file. Would it be possible for you to upload the file directly (like shown in the video here: KX Introductory Video- #2)? You may need to make sure the file is in layout mode so the file size is small enough to upload.

Thank you for valuable help, here is my file

G square A1_A14_lay.fsp (289.7 KB)

I want to know the meaning of ellipse point.
How can I determine which mode converted to which mode?

I checked the setup of the file with the details provided in the paper and I noticed a few differences:

  • I think the scattering rate of the graphene material doesn’t match. The scattering rate calculation method is discussed here:Scattering rate in surface conductivity of graphene
    From the post, the formula for scattering rate in eV should be hbar/(2tao1.6e-19) where tao is the scattering time which is 0.5 ps in this case

  • I am also not sure about the chemical potential of the graphene since it didn’t seem to be provided in the paper. This may make it more challenging to get the result

  • The thickness of the Au ground plane used in the paper was 100 nm

  • The source in the simulation file was set up to inject circularly polarized light, however, from the paper, the incident light is x-polarized

  • The frequency range of the source should be adjusted. However it’s not clear to me that the resonance will occur at the frequencies shown in the paper since the chemical potential of the graphene may not match what was used in their calculations, so the range may need to be increased if the resonance position is shifted

The calculated polarization ellipse has a specified resolution (number of points in the ellipse), and the “ellipse_point” parameter of the Gs_all and Gp_all correspond to the data point number on the ellipse. In your file, the resolution is set to 1000 so ellipse_point will go from 1-1000.

To get Rxx and Ryx, you can look at the maximum amplitude of Gs_all and Gp_all.

Hopefully this helps!

1 Like

Thank you nlui,

first:
I adjust the scattering rate.

2nd:
The chemical potential(Fermi energy) in the paper (1eV).

3rd:
the injected source has (Amplitude=0)in y-direction in the previoues file
just to make (polarization ellipse analysis group) to work properly.

4rd:
I modified the thickness of gold.

5th:
I widened the range of incidence.

6th:
I think that I can exclude the polarization from the electric field
components.

But still problems!

G square A1_A17_lay.fsp (289 KB)

Thank you nlui,

first:
I adjust the scattering rate.

2nd:
The chemical potential(Fermi energy) in the paper (1eV).

3rd:
the injected source has (Amplitude=0)in y-direction in the previoues file just to make (polarization ellipse analysis group) to work properly.

4rd:
I modified the thickness of gold.

5th:
I widened the range of incidence.

6th:
I think that I can exclude the polarization from the electric field components.

But still problems!
G square A1_A17_lay.fsp (289.5 KB)

Thanks for pointing out the chemical potential value!

I checked the settings again, but so far I have still not been able to figure out what the problem is since the values now match the paper. I suspect that either there is still some inconsistency in the graphene material properties, or a finer mesh might need to be used over the graphene in the x and y directions…