Learning Forum

[Chenxi Zhang]

Hi,

I loaded a .ldf file of a farfield simulation from FDTD to MODE and tried to overlap it with a gaussian beam. Here are the error messages: 

z1 = loaddata("z1");
::monitor  ::monitor_1  ::scat_ff::z1  ::scat_ff::z2  ::scat_ff::x1  ::scat_ff::x2  ::scat_ff::y1  ::scat_ff::y2  ::scat_ff::index  ::source
overlap("z1","gaussian1");
Error: prompt line 1: in overlap, no d-card called: z1 was found
overlap(z1,"gaussian1");
Error: prompt line 1: the first 2 arguments of overlap must be strings

In the D-card window I see that d-card 4 has name z1, but here it says z1 is not found. I tried ?getdata and get the following message:

::gaussian1
::monitor
::monitor_1
::scat_ff::z1
::scat_ff::z2
::scat_ff::x1
::scat_ff::x2
::scat_ff::y1
::scat_ff::y2
::scat_ff::index
::source

So I also tried names "::scat_ff::z1" and "scat_ff::z1". Both were not found. 

I would like to know why and how can I get the correct name of a d-card. Thanks.

[Amrita Pati]

Hi Chenxi,

If you haven't already, could you try running the following and let me know if the issue still persists:

ol = overlap("::gaussian1","::scat_ff::z1"); #Both d-cards (with the colons) within double quotes 

Reagrds,
Amrita

 

 

[Chenxi Zhang]

Hi Amrita, 

Thanks for your reply.

Here's what i got:

ol = overlap("::gaussian1","::scat_ff::z1"); 

Error: prompt line 1: in overlap, no d-card called: ::scat_ff::z1 was found

 

 

[Amrita Pati]

Hi Chenxi,

Thanks for letting me know! Let me test somthing very similar and get back to you.

Regards,
Amrita

[Amrita Pati]

Hi Chenxi,

These commands would work given that certain conditions are satisfied:

1. The FDE plane (in which the Gaussian Beam is created) is same as the monitor plane. Here if the monitor and FDE are both z-normal, then the overlap script command should work. But if they are not in the same plane, you will get this error message.
2. The wavelength at which the FDTD monitor data is generated must be the same as the wavelength of the Gaussian Beam.
3. The size of the monitor and the size of the FDE region used to create the Gaussian beam must also be the same.

If these three conditions are satisfied, you should get the result as expected.

Please let me know if you continue to face issues.

Regards,
Amrita

[Chenxi Zhang]

Hi Amrita,

Thank you again for your reply. 

I think I've already satisfied these conditions but the same error message still appears. 

The set-up of my FDTD simulation includes only an electrical dipole and a DFT monitor. I've set both the source and target wavelength to be 1.55 microns(the same as the default gaussian beam wavelength). And both the FDE plane and the monitor plane are z-normal(x span from 0 to 4, y span from 0 to 4). Are there any simulation steps I am missing here?

 

Regards,

Chenxi

[Amrita Pati]

Hi Chenxi,

Thanks for sharing more information! I can't really think of any other reason. But let me spend some more time on this and come back to you. 

Out of curiosity, do you aim to take the FDTD results from the DFT monitor (called "monitor") or one of the monitors inside the analysis group (called "scat_ff")? Secondly, I believe this screenshot was taken after the simulation was done running. But I am wondering why there is no data in the monitor, but there is data in the analysis group.

Regards,
Amrita

[Chenxi Zhang]

Oh your response is so inspiring! I didn't realize before that I wasn't logging data in my monitor. Once I changed the plane from z=0 to z=0.5 I was able to successfully overlap the monitor data with the Gaussian beam. Thank you so much for your help.

I still have a question about this. I'm still wondering why could I overlap the monitor data with gaussian beam but could not using the "z2" monitor inside the analysis group, even if they are exactly the same plane.  

 

[Amrita Pati]

You are welcome, Chenxi!

If you edit the analysis group, then go to Analysis--Variables, there should be a variable called "target wavelength", is there any chance that this value is set to something other than 1.55 um:

If yes, I would recommend changing it to 1.55 um and then recalculating the overlap. If it is already 1.55, let me know, I will try to think if there is any other reason that this could be happening.

Regards,
Amrita

[Chenxi Zhang]

It is already 1.55 um.

[Chenxi Zhang]

Hi Amrita, 

It's been a while since we discussed about the issue, which is to get the overlap between the gaussian beam and the scat_ff profile. Is there any updates on this?

And I was wondering how did you get the overlap in your first response:

 

Thanks a lot. 

Regards,

Chenxi