Application of two-photon spectroscopy in the study of trivalent rare-earth ions in crystals

Abstract

To study the role of stepwise and relaxation processes under effective excitation of anti‐Stokes luminescence of rare‐earth (RE) ions in crystals the time‐shifted pulse method is used. It is shown that direct comparison of measured single‐ and two‐photon luminescence excitation spectra often enables one to make immediate conclusions on the position and classification of electron levels of RE ions. The Tb3+ and Eu3− level structures (crystal CaF2) in the near ultraviolet are considered as an example. The peculiarities connected with the polarization characteristics of the two‐photon absorption of radiation by the trivalent RE ions in a crystal matrix are discussed. To obtain the two‐photon spectra a frequency‐tunable organic dye solution laser (ODSL) is used.

Upconversion luminescence of Ca1−xHoxF2+xand Sr0.98−xEr0.02HoxF2.02+xpowders upon excitation by an infrared laser

“…Upconversion materials are used for the visualization of infrared radiation. At present, there are a significant number of articles devoted to the investigation of upconversion luminescence of Ho 3+ in MF 2 (M = Ca, Sr, Ba, etc) crystals under excitation of 5 F 3 , 5 S 2 ( 5 F 4 ), 5 F 5 , 5 I 5 , 5 I 4 , 5 I 6 , and 5 I 7 levels [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Fluorite-type materials doped with rare-earth ions have specific features: low phonon energy and the tendency to form multiple cluster configurations of dopant ions [12,[21][22][23].…”