Learning Forum

[Raikage97]

The results reported in this example:

https://support.lumerical.com/hc/en-us/articles/360042243634-Electro-optical-modulator-based-on-a-graphene-coated-waveguide

are inchoerent with the result of the simulation. I didn't modify any parameter, I just ran the code.

[GWANG]

Hi Raikage97
Could you please describe a bit more on the problem you are seeing?

[Raikage97]

Yes sir. When I run the code graphene_electro-optic_modulator_1, I have the following error:
When I run graphene_electro-optic_modulator_2, I have the following error:
The same of the first one. After getting the simulation data using script get_top_Ef_data.lsf and get_leftwall_Ef_data.lsf, running code graphene_electro-optic_modulator_transmission_calc.lsf I get the following result:

Simply put, I can't get your results.


I am also curious to know in detail, if it is possible, how the parameters m* and Ec were derived to schematize graphene on DEVICE.
Moreover in the article it is stated that the guide is single mode, but actually performing the simulation with FDE more modes appear. How is this possible?

[kghaffari]

Hi Carlo,
Thanks for posting this. I tested the example and can confirm thereÔÇÖs a geometry creating issue in the version 2021 R2.1 when running the CHARGE project files. We recommend downgrading to previous major release 2021 R1.x. I tested the example in 2021 R1 and it works in that version. Sorry for the inconvenience.
For m* and Ec, their derivation is described in detail in the example. Basically, they are used as fitting parameters to match the density of states between the 2D and 3D model.
Regarding the mode, we indicate the mode that the device has been intended to operate for:
This is the mode the consequent calculations and derivation of transmission is based on.
All the best Khashayar

[Raikage97]

[Raikage97]

Thanks kghaffari, I will try to do what you told me.
Best regards Carlo

[Raikage97]

I tried to do what you said, but I still have the same error:
"average variation in charge over contact 'gate' interfaces exceeds tolerance. check surface doping profile and surface material properties "
By changing the thickness of the graphene and varying the fit parameters, I still have the same error, but the simulation tends to go little further

[kghaffari]

For future reference: we confirmed the example can be run fully with the mentioned version of the software.