Learning Forum

[niazulkhan]

[Guilin Sun]

The visualizer shows the monitor data. Its largest size is determined by the monitor size. When you increased the pitch, did you change the monitor size at the same time to cover the whole simulation region? I usually suggest users to use larger monitors spans to be outside of the simulation region. So small change of FDTD region will not need to change the monitor.
BTW: you can only decrease the x-limit and y-limit from their largest values by editing the graph:

[niazulkhan]

Thanks for your reply. I understand that largest size is determined by the monitor size. However, look at the attached images: though the monitor_1 size is 5um x 5um, the heat profile only shows 0.34 um x 0.34 um. I cannot change it by any means. I am not sure whether it is fixed by scripting at any place.
And also, look at the plot settings, there is no "Axes limits" option as yours.

[Guilin Sun]

The actual, useful size of the monitor is inside the simulation region. If the period is only 0.34um*0.34um, you will not be able to get any data outside of this range! Please check your simulation region.

[niazulkhan]

Hello, Thanks a lot. but it does not help. I increased the simulation region to a dimension of 0.54 um x 0.54 um. and the heat profile always shows the same x- and y ranges. The monitor_1 size was 5um x 5 um. See the images below:

Though I can't change the X- and Y- range in any way, I can change the Z-ranges by simply tuning the monitor_1 size.
I would appreciate it if you could help me in this regard.

[Guilin Sun]

It is originally from FDTD simulation with optical absorption. You will need to modify FDTD. Please follow the procedures in the example.

[niazulkhan]

I modified (increased) the FDTD geometry as well as the analysis group. When I do this, FDTD solver responds accurately as visible in the .mat file (Pabs_diabolo_array_1mW.mat) which contains the optical absorption data for the extended x-and y-axis range in the analysis group (Pabs_adv). However, the HEAT solver does not respond even after importing the .mat file. It seems that the axis limits froze and are unable to be changed.

[Guilin Sun]

This is because you only changed the FDTD simulation region but did not change the monitor size.

[niazulkhan]

I did change both the FDTD and analysis group dimension as you highlighted above.

[Guilin Sun]

This is very strange. Please check the following:
1: after FDTD simulation, visualize the E field from the DFT monitor:
2:runanalysis, and visualize the Pabs
3: load the matlab data, and visualize it:
4: after modify HEAT simulation region, load the matlabdate, and visualize it:

You may forgot to load it. I guess this is the root cause.

5: run HEAT and check the result

Monitor has size of 5*5um, so you do not need to change. But in general you need to check.
Please follow the above procedure and check which part went wrong.

[niazulkhan]

Thanks. It works for me.

However if I change the dimension of the analysis group as in the image below, will not it change the power density defined by the "input power" in the "Analysis" tab of the analysis group because I think the input power is defined for this area/volume.
Thanks.

Niazul

[Guilin Sun]

Sorry, Power is not "defined", it is an input parameter. If you want, you could do that way by calculating the power from the source amplitude and area. You can use "model" to pass parameters.

[niazulkhan]

Thanks, but my question is on the choice of the dimension of the analysis group. Why is the dimension 0.23 um x 0.22 um x 0.06 um? I know the antenna size is 0.15um x 0.15um x 0.05 um.

[Guilin Sun]

I think it is a little bit arbitrary. The monitor should be a little larger than the absorption region due to discretization and internal interpolation. If I do it, I would prefer to use 02*0.2*0.1 um, again it is arbitrary. It is the refractive index monitor data that is determines where the absorption is (the absorption is proportional to imag(permittivity)).
The online examples only give some description on critical parameters, which could be improved later for easy understanding.

[niazulkhan]

thanks a lot.

[niazulkhan]

Another question I have in mind: if I extend the axis to (for example) 0.9 um x 0.9 um which will cover all the diabolo antennas of the array, I can visuazlie the absorption profile of all the antennas covered by this dimension in the Pabs visualizer as below:

However, in the heat profile I can only see one antenna as seen below. If I am doing anything wrong?

[Guilin Sun]

Could you please follow up the previous procedures I suggested and check where leads this issue?

Please narrow down the questions for this post. I believe that the original question has been resolved for periodic case.

For your new FDTD monitor profile, I am not sure the simulation condition so I cannot comment. If you still use the plane wave plus periodic BCs the results are incorrect as the antennas have different field profiles. Please write a new post with more details, if you still have questions. The ALF policy is for one question one answer.

[niazulkhan]

I understand the problem for different heat profiles, there was a problem in the meshing. Thanks. I am writing a separate post.