Do I have to determine both n and k values when importing a new material(ZnO)?


#1

Dear Nlui.
Hello and good time.

My material is ZnO; so, there is no data according to the ZnO material inside the lumerical solution; hence, i have to determine the values of n and k, my question is:

  1. Must I determine k value or only n value is enough?
  2. In my structure should I consider mesh size or it is better to consider the mesh as default by the software?

Thank u so much
Best Regard
Ali


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#2

Hi,

This knowledge base article provides the details on the import of user-defined materials.

https://kb.lumerical.com/en/ref_sim_obj_importing_spatial_nk.html

I hope this will be of help to you in importing ZnO, n and k values. You can also look at the literature where the n,k values have been measured with ellipsometry. Also, certain handbooks also contain the values.

Best Wishes,

Vivek


#3

Hello dear Vivek.

At first thank you so much according to the good recommend about the n and k value. Actually, I have selected ZnO as bulk material; so, There is only one value (n=2), there is no the value of k for bulk ZnO material. If I want define only n and k equal zero, is it right or not?
Thank you so much
Best Regard
Ali


#4

Hi @alivazinishayan,

As you mentioned, the ZnO insulating material normally do not have an extinction coefficient k. In this case, you can surely define this dielectric layer using the real part of the refractive index n without k. If you’re assuming that the dispersion effect of the refractive index n over the broadband (i.e., visible range) is not that critical in your simulation model or considering only single frequency, you can simly impose the constant n value in your model as below.

On the other hand, if you want to simulate the dispersion characteristic of ZnO over the specific range, then you can import the refractive index n spectrum (please refer to this KX contents). You can download the refractive index of ZnO material following useful website: http://refractiveindex.info/?shelf=main&book=ZnO&page=Bond-o. In your case you might need to insert k value as 0 in your sampled data set of (n,k vs. wavelength) when you import n, k values via sampled data in Material Database window. After you apply newly generated refractive index information of ZnO into your geometry (i.e., rectangle), you can set the level of the k over the broadband as possible as zero by adjusting the “imaginary weight” parameter in Material window. It’s important to keep in mind that it’s very hard to obtain the k value as “0” in this situation unless the n value is just a flat line (constant). As you fine-tune the imaginary weight parameter of ZnO material to make a better fitting, you can obtain nearly zero level of k (i.e., 10^-10) as a following example.

I hope this would be helpful for you.