Confusion to use Heat Transfer and FEEM module together



I have written my followed steps and queries in attached docx file. Also I am attaching the model and script files used during the work.

I am facing troubles to use heat Transport and FEEM model together. Also may I know some reference paper with which the Heat Transport model in consistent for benchmarking.

Waiting for response. Cheers!!

I am using a simple strip waveguide having width.docx (1.9 MB)

T.mat (31.2 KB)
thermal_tuning_index_perturbation.lsf (2.2 KB)
thermal_tuning_waveguide_FEEMsweep.lsf (1.1 KB)

thermal_tuning_waveguide_FEEM_11.ldev (6.2 MB)



May I ask to post the info about your simulation and also your questions within the topic rather than as an attachment in word file? This will allow the users to easily obtain the information and help you with your issue.


Hi @sunny.chugh

As @mmahpeykar mentioned, please post your follow up questions directly into the forum so that it is searchable.

Regarding your inquires:

  1. The “power” sweep for the FEEM simulations does not seem to be set properly. The index values are set to zero after a few points and it results in sharp drop of effective index. Here is the plot when the problem is fixed:


  2. Here is the plot of effective index when the nk import is disabled:

The first mode has effective index of ~3.93 which matches with the power sweep results. This mode interferes with copper and you may try to select other modes of interest for your purpose.

I also recommend you to lock the mesh for both the HEAT and FEEM simulations. In HEAT this guarantees that sweep results have the same dimensions. In FEEM simulations, this guarantees that the change in effective index is due to perturbation in index rather than due to grid sizes.

Hope this helps.



That’s very helpful. I want to know one more thing that how to see mode profiles using script commands like Ex, Hy, etc, similar to the way we can see neff as circled in below images. I have put fields in power sweep window as well.


Hi @sunny.chugh

There is a problem with the visualizer that you cannot visualize the field profiles at the moment. I will report it for a fix.

Regarding visualizing the data through the script, lock the mesh and follow a similar script as is explained in the link below:

For example, for the E1 fields (electric field of the first sweep result):

fields = getsweepresult("power","fields");

x = fields.x;

y = fields.y;

z = fields.z;

C = fields.elements;

data = unstructureddataset("test",x,y,z,C);

modenumber = fields.modenumber;

f = fields.f;

E1 = pinch(fields.E,3,1);






@bkhanaliloo Thanks very much for your response. Following the weblink:

I am using Cu heater rather than Al heater. I am attaching the lumerical device file ( ). First I am running the sweep and then saving temperature profiles using commands


Then I am importing temperature profiles in mode solution file as attached (thermal_tuning_MODE_2_a.lms (283.7 KB))

I am importing script file (thermal_tuning_waveguide_2D_mode_sweep_Twg1.lsf (714 Bytes)
) in it to plot neff for various heater power. Screenshot of result is attached as

As the design includes Cu metal heater, therefore there should be some plasmonic absorption losses which can be calculated using negative values of propagation constant or neff as shown in page 3 of attached paper(josab-35-10-2532.pdf (4.1 MB)

but here as seen in image file there are no negative values of neff. So how will the plasmonic losses be calculated?


Hi @sunny.chugh

Thanks for sharing the simulation files.
Your geometry in MODE does not include Cu or Al, it has only lossless materials. As a result there will be no loss in the waveguides.

If you want to see the loss due to the heater, you need to add the object into the MODE/FDE simulations.