Laser ions ytterbium

Finally, in the last section of this chapter (Section 6.6), we will treat two aspects that are of great relevance in the optical spectroscopy of solids. First, we will introduce a semi-empirical method (due to Judd, 1962 Ofelt,1962) that analyzes the absorption spectra of trivalent rare earth ions in crystals to search for new efficient phosphors and solid state lasers. Secondly, we will treat a relatively new topic related to optical centers in solids the optically induced cooling of trivalent ytterbium doped solids. 

The rare earth (RE) ions most commonly used for applications as phosphors, lasers, and amplifiers are the so-called lanthanide ions. Lanthanide ions are formed by ionization of a nnmber of atoms located in periodic table after lanthanum from the cerium atom (atomic number 58), which has an onter electronic configuration 5s 5p 5d 4f 6s, to the ytterbium atom (atomic number 70), with an outer electronic configuration 5s 5p 4f " 6s. These atoms are nsnally incorporated in crystals as divalent or trivalent cations. In trivalent ions 5d, 6s, and some 4f electrons are removed and so (RE) + ions deal with transitions between electronic energy sublevels of the 4f" electroiuc configuration. Divalent lanthanide ions contain one more f electron (for instance, the Eu + ion has the same electronic configuration as the Gd + ion, the next element in the periodic table) but, at variance with trivalent ions, they tand use to show f d interconfigurational optical transitions. This aspect leads to quite different spectroscopic properties between divalent and trivalent ions, and so we will discuss them separately. 

Gandy and Ginther (132) studied simultaneous laser action of neodymium and ytterbium ions in glass. The base glass was LiMgAlSi03. When singly... 

A neodymium-ytterbium-coupled rare-earth ion system was given extensive study by Peterson and Bridenbaugh (109, 166) Peterson et al. (167) and Pearson and Porto (168). The simultaneous doping of Nao.5Gdo.5-W04, or Calibo (168) glass with neodymium and ytterbium results in a resonance-coupled system in which energy pumped into the neodymium appears as fluorescence from the ytterbium. The fact that the energy absorbed by the neodymium is rather efficiently transferred to the ytterbium results in a substantial reduction in laser threshold for ytterbium. 

The commercially important samarium-containing minerals are treated with concentrated sulfuric acid or, in the case of monazite, with a solution of sodium hydroxide (73%) at approximately 40°C (104°E) and under pressure. The element is separated from the solutions via solvent extraction or ion exchange. Sm salts are weakly yellow and may exhibit ion emission. Sm ions show luminescence and are sometimes used to generate lasers. Samarium is used in the manufacture of headphones and tape drivers, see ALSO Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Lutetium Neodymium Praseodymium Promethium Terbium Ytterbium. 

F ure 17-10. Sketch of the setup used to measure optical properties of a sol-gel waveguide doped with erbium/ytterbium ions. Different pigtailed laser diodes and dfferent output coupling configurations may be mixed, in order to perform specific measurements. 

---