# Calculate dielectric function from n and k

Dear All,

I am trying to calculate the dielectric function of a thin silicon film from the real and imaginary values of the refractive index, which I have for wavelengths between 300 and 900 nm. If I have the n and k values (real and imaginary components of the refractive index), could anyone advise me as to how excactly to calculate the dielectric function from these values?

Am I correct in thinking the formulae shown under the 'Relation to dielectric constant' section in the following link are the right formulae to use?

http://en.wikipedia.org/wiki/Refractive_index

Any advice would be greatly appreciated.

Thanks.

Assuming that the material is nonmagnetic ($\mu = \mu_0$), you can just use $\epsilon = (n+ i k)^2$. Of course, you have to be careful to make sure you get the signs of the real and imaginary parts of the permittivity right.
In optics, the statment $$\mu=\mu_0$$ is not an assumption about the material being non-magnetic, but a definition. All magnetic effects are taken care of by the wavenumber dependence of the dielectric constant.