frequency dependent refractive index comsol

Hi,

I am trying to solve the electromagnetic field of a 60 nm silver cylinder in a 2D scattered field RF module of COMSOL, and I have the optical properties like refractive index (n+i*k) which depend on wavelength considered, i.e. from 300 nm to 800 nm.

What I have dong is listed below:
(1) I edit two file named Agn.txt and Agk.txt, which contain the refractive index (n, k) at different wavelength from 300 nm to 800 nm.
(2) I define two functions named Agn and Agk by interpolation using data from Agn.txt and Agk.txt.
(3) I specify the material properties in term of refractive index as Agn(lambda_rfweh)+i* Agk(lambda_rfweh)

But the result is different with what I calculated using discrete n+i*k values at that wavelength. My question is
What is error from?
What is the best possible way I can incorporate the refractive index (n+i*k) for different wavelength (300-800 nm.) in scattered field problem?

Thanks so much!

Fuyi

hi! I'm working on almost the same problem. It's so great to see the thread here. But i'm stuck even with entering the frequency dependent properties into a file. hahaha.

Could you please share some insights or ideas about how you managed to make COMSOL read from a data file and at the same time match each entry with a specific wavelength? My second question is, in case you are also trying to get a spectrum of scattering cross section, how can we make COMSOL sweep through the wavelength range of interest?

Thank you very much! I appreciate it with gratitude.

I think all can be done with COMSOL script.