Optical properties of LiNbO3 : Cr crystals co-doped with Germanium oxide

E. Camarillo, H. Murrieta, J.M. Hernandez, R. Zoilo, M.C. Flores, T.P.J. Han, F. Jaque

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Lithium niobate (LiNbO3) crystals doped with chromium ions show a clear green colouring reflecting the absorption profile of the dominating [Cr](Li) defect centres. A significant change in its colouration takes place when it is co-doped with other valency impurities such as Mg2+, Sc3+ and W6+, above a certain threshold concentration. This concentration singularity has been attributed to the formation of [Cr](Nb) centres coexisting with the [Cr](Li) centres. In this work, we extended the investigation on the effect of co-dopant ions in Cr:LiNbO3 to tetravalent cation such as GeO2. A singularity in the relative intensity of the (4)A(2)-> T-4(1) and (4)A(2)-> T-4(2) absorption band was observed for a concentration of similar to 1.5 mol%, compared with 4.5 mol% for Mg2+. The photoluminescence emission spectra also reveal a new emission band, at a lower energy than the [Cr](Li) centre, corresponding to this threshold concentration. A charge compensation model is proposed to explain the role of cation impurities and results are compared with those of other valence impurities.
Original languageEnglish
Pages (from-to)747-750
Number of pages3
JournalJournal of Luminescence
Volume128
Issue number5-6
DOIs
Publication statusPublished - May 2008

Keywords

  • absorption
  • luminescence
  • Cr
  • Ge
  • LiNbO3

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