Is the Refractive Index Constant Despite Rising Extinction Coefficient?

[Ravian]

is it possible the refractive index remains constant while its extinction co-efficient rises as function of frequency? if yes when does this typical arise? i imagine that this can happen at the absorption edge of transmission spectra of a semiconductor but i don't find any explanation to this.

 

[Bob S]

The index of refraction and the absorption are related through the Kramers Kronig relations. If the index of refraction is independent of frequency (wavelength), then the absorption coefficient has to be independent of frequency also.

See

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

"The real and imaginary parts of the complex refractive index are related through use of the Kramers–Kronig relations. For example, one can determine a material's full complex refractive index as a function of wavelength from an absorption spectrum of the material."

Also see this Wikipedia article on the Kramers Kronig relations.

http://en.wikipedia.org/wiki/Kramers–Kronig_relation

Bob S