High-resolution spectroscopy of functional dielectrics with rare-earth ions

A brief review of recent studies of crystals doped with rare-earth ions performed at the Institute of Spectroscopy of the Russian Academy of Sciences (ISAN) using high-resolution wide-range optical Fourier spectroscopy is presented. The results of a study of inhomogeneous broadening and the fine structure of lines in the absorption and luminescence spectra of crystals with rare-earth ions caused by random deformations, the isotopic structure in luminescence spectra associated with matrix isotopes, and anticrossings of the crystal hyperfine levels in a magnetic field are discussed. It is shown that the hyperfine structure in luminescence spectra can be used to implement a luminescence thermometer for the region of ultra-low temperatures.