Development of the Kramers-Kronig Method for Spectra of Polarized IR Radiation Reflected from the Surface of Low-Symmetry Crystals

摘要

The generalization of the Kramers-Kronig method obtained in this work is proposed as a means for processing spectra of polarized IR radiation reflected from the surface of low-symmetry crystals in which the directions of the major axes of the dielectric constant tensor depend on the frequency. It is shown that one can obtain in this way all components of the complex reflectance tensor using only three reflectances spectra measured for different directions of linear polarization of the incident wave under conditions where the reflected wave falls directly on a detector. The problem is reduced to the system of integral equations, and an efficient numerical solution method is found. The problem of reconstructing the complex dielectric tensor starting from the reflectance tensor is discussed. The case of a monoclinic crystal is analyzed in detail. As an example, the application of the generalized Kramers-Kronig method to the reflectance spectra of the (ac) face of the bismuth oxide crystal having a monoclinic lattice is considered.