Multicenter structure and dynamical processes in the rare earth doped garnet and sesquioxide laser crystals and ceramics

摘要

This article presents new data on multicenter structure of the optical spectra and of emission dynamics of the doping ions in various types of crystalline and polycrystalline cubic laser materials (garnets, sesquioxides). It is inferred that the satellite structure of the active ions is induced by crystal field perturbations inside the near neighbor associations of the active ion with specific defects of the host lattice (P-type satellites independent on doping concentration) or with other active ions (M-type satellites dependent on doping concentration). Such satellite structures are described for various rare earth ions; including Nd~(3+), Pr~(3+), Er~(3+). In case of the garnet crystals, both types of satellites are present, and the satellites P can be connected with departures from stoichiometry; in garnet ceramics, they are much less intense. In contrast, the structures of M satellites are similar in garnet crystals and ceramics, indicating similar distribution of the doping ions in the host matrix. The luminescence spectra of these materials are influenced by the emission quantum efficiency of the various centers. In the case of sensitized materials, the mutual crystal field perturbations could modify the absorption spectra on both the sensitizer ions. In the case of materials with charge compensation, the electric charge disordering determined by the process of compensation strongly influences the optical spectra of the doping ions and their distribution. The relation between the global spectroscopic properties and those measured by microscopic methods is also considered. The connection between the fabrication process, structure, spectroscopic, and laser emission properties is shown and it is inferred that the multicenter structure of the spectra, together with emission dynamics, can be an efficient tool for investigating the microstructure of the laser materials, for optimization of laser properties, or for tailoring new laser materials.