semiconductor power absorption


Dear all,

Now I am trying to calculate the absorption of a 3D structured semiconductor. But I hope to get the power absorption distribution in the XY surface. That means I need to integral the absorption in Z axis. But I don’t know how to integral the Z axis data. Thanks for any help.


Hi, @u3003404 !

From what you’ve said, I can understand you need to obtain obsorpsion per unit surface area.
It seems that you may need to take simply the attenuated values of the intensity, travelled to the bottom of the structure.
There is no problem with integration, either.

To answer more specific, could you provide a simulation file you are using?


Sorry to reply so late to you. Actually, I tried to change the code to realize this function. But I haven’t solved it yet. Here I attached the original and revised model. Please help me check the code. Thank you so much.1 - original.fsp (243.8 KB)
1 - revised.fsp (244.0 KB)


Hi, @u3003404 !

Sorry for delayed reply.
While I am checking your simulation files, I wonder are you interested in absorption, which is caused only by material losses or you imply attenuation, which is the sum of absorption and scaterring ?


Hi, @u3003404

To help you solve the issue, I used the lumerical example:
Please, try “usr_absorption.fsp” file with the script I attached to the post.

In the script, I’ve got rid of the routines that had been used for purposes not relevant to your problem.
The script integrates the absorbed power other the entire z span accesible stored by Pabs.z array.

usr_absorption_INTEGRAL_OVER_Z.lsf (908 Bytes)

I wonder why are you using the TFSF source ?
For your structure simulation can be performed following this way, but don’t forget to change the source type to plain wave if neccessary.

Does this help?


Thank you so much. It’s really helpful. But actually I have got the help from teacher Sun several days ago. So here I attach the modified model.
But I don’t know the difference of TFSF and plain wave. Can you tell me the difference.
1_plot.lsf (355 Bytes)
1 - revised-lum.fsp (241.7 KB)


Nice to hear that your problem is solved.

The TFSF source allows you to obtaine the scattered fraction of the field, which is due to a structure that changes the field from free propagation. Actually, this is not a source, but a procedure that calculate the field in a given volume.
More details, as well as examples, are available here

If have any further questions, do not hesitate to ask them.


Dear @u3003404

Other than studying scattering field, TFSF is introduced to be used in cases where your structure is not periodic but the source in experimental setup is still plane wave. For example, TFSF is quite useful to be used when boundary conditions are PML as using plane wave with PML BCs can create edge effects:

I also recommend you to take a look at this page to learn more on how to use this source properly:



Thank you so much. I will check and clarify.