LAUSR

Abstract. We devote this article to the spectral analysis of volume holograms recorded in materials with diffusion-based formation mechanisms. Two media of different natures were examined: polymer material with dye molecules photoattachable to macromolecules (PQ-PMMA) and photochromic additively colored fluorite crystal (CaF2). Differential spectra of holograms refractive index and absorbance were determined by two approaches: numerical approximation of both spectral and angular hologram response (selectivity hypercontour) by coupled-wave theory and processing hologram spectra by Kramers–Kronig dispersion relations. The principles of the two approaches, results of their application, and advantages and disadvantages are discussed. Kramers–Kronig relations can be usefully applied in cases where the nature of holograms formation is well studied, whereas the hypercontour approach is indispensable for obtaining the values of absorbance and refractive index modulation; therefore, a combination of both the techniques is a powerful tool for fundamental investigation of the hologram formation mechanisms.