Equivalence of Kramers-Kronig and Fourier Transforms to Convert between Optical Dispersion and Optical Spectra

Abstract

The complex refractive index relates optical dispersion, which describes the variation of refractive index with wavenumber, to the corresponding absorption spectrum; both phenomena are associated with the same underlying molecular property, electric dipolar moment. Instead of the traditional Kramers-Kronig transform for interconversion between absorption and dispersion, we show the practicality of Fourier transforms for this purpose, and prove the equivalence of these transforms. We demonstrate the transforms with infrared data for liquid benzene.