Kramers—Kronig analysis of infrared reflection spectra with parallel polarization for isotropic materials

Kramers—Kronig analysis of reflection spectra from a single interface with parallel (p) polarization has been developed by using non-linear least square refinement and its application is studied theoretically with regard to a phase correction term. The errors in phase shift and complex refractive index obtained by Kramers—Kronig analysis have been examined for such techniques as external and total internal reflection spectroscopies by using spectral simulation with model spectra composed of complex refractive indices based on dispersion theory. From these calculations, it has been shown that the complex refractive index can be obtained for isotropic samples by Kramers—Kronig analysis using p polarization with the same accuracy as for perpendicular (s) polarization. The combination of Kramers—Kronig analysis for each polarization allows one to obtain the complex refractive index of anisotropic materials. Furthermore, the complex refractive index of thin film samples on metal can be obtained from reflection-absorption spectroscopy (RAS) by Kramers—Kronig analysis including a non-linear least square refinement procedure.