How to calculate transmittance of the gold nano structure(upload File)


Hello, I would like to calculate the transmission when changing the spacing between gold nanostructures. And I sweep simulation’s region (x span) and calcurate the transmittance.
But if I placed the transmittance monitor as upload File, the result every monitor represented different.
So I can’t understand the correct position of transmittance monitor and how to calculate the transmitance.
Or does this result correct??
Please tell me how to calculate the transmittance of my structre.二層目金なし_ピッチ変化_光源角度30.fsp (376.7 KB)


Hi @sugano

I am not quite sure what monitors were you referring to. If the monitors are located in the substrate region below cr layer and cover the entire simulation region in the xy-plane, results should be identical for lossless material. Here are some recommendations to modify the simulation file:

  1. Make sure that there is at least half the maximum wavelength distance (1um in your case) between the PML and edge of critical objects.

  2. Extend your substrate into PML to avoid reflections.



thank you for replying, bkhanaliloo.
I reffer to monitors are T,T1,T2,T4 and Is the content you said as shown in the picture (you said " distance (1um in your case) between the PML and edge of critical objects")?

Sorry I can’t understand “2.Extend your substrate into PML” .and monitors(T,T1,T2,T4) results aren’t same.


Hi @sugano

Please see the screenshot below:


It looks like the silicon material is lossy:

This means that light will be absorbed as it propagates inside the silicon substrate. Thus you should not expect that transmission from all the monitors to be the same.

Hope this was helpful.


Thanks bkhanaliloo.
Then, where should I put the monitor to calculate the transmission?
I think that I change part which is higher than a silicon substrate and want to calculate transmission to grope for the most suitable Near-infrared light transmission structure.
Is there any good way to do it?


Hi @sugano

I am not quite sure if I understood your question properly. Are you looking to calculate the near field results?

Since the substrate is lossy, transmission results will vary based on the location of your monitors. Depending on your experimental setup or where you want to measure the transmission, you can select the results of each of these monitors.

You need to check and make sure that material in your experimental setup or the reference paper match the simulations. Then you can find the near field results at any location inside the substrate (which will vary based on the position).

Hope this was helpful.


Thanks bkhanaliloo.