Is the Refractive Index Constant Despite Rising Extinction Coefficient?

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SUMMARY

The refractive index can remain constant while the extinction coefficient rises as a function of frequency, particularly at the absorption edge of transmission spectra in semiconductors. This phenomenon is explained through the Kramers-Kronig relations, which connect the real and imaginary parts of the complex refractive index. If the refractive index is frequency-independent, the absorption coefficient must also be frequency-independent. Understanding this relationship is crucial for analyzing optical properties in materials.

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  • Understanding of complex refractive index
  • Familiarity with Kramers-Kronig relations
  • Knowledge of semiconductor absorption spectra
  • Basic principles of optics and light-matter interaction
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  • Study the Kramers-Kronig relations in detail
  • Explore the concept of complex refractive index in materials science
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Optical physicists, materials scientists, and engineers working with semiconductors and optical properties of materials.

Ravian
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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.
 
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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
 

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