Structural characterization of noncrystalline solids and glasses using solid state NMR

Three different broadband sensitization concepts for optically active erbium ions are reviewed: 1) silicon nanocrystals, with absorption over the full visible spectrum, efficiently couple their excitonic energy to Er3+, 2) silver-related defect states in sodalime silicate glass have absorption in the blue and transfer energy to Er3+, and 3) organic cage complexes coordinated with well-chosen chromophores serve as broadband sensitizers in the visible. Energy transfer rates, efficiencies, and limiting factors are addressed for each of these sensitizers. Implications of the use of strong sensitizers for planar waveguide design are illustrated by using a model for the sensitizing effect of ytterbium.

Broadband sensitizers for erbium-doped planar optical amplifiers: review

[∗] Dr. A. Royon , Dr. M. Bellec , G. Papon , Dr. B. Bousquet , Prof. L. Canioni Centre de Physique Moleculaire Optique et Hertzienne University of Bordeaux 351 Cours de la Liberation, 33405 Talence (France) E-mail: l.canioni@cpmoh.u-bordeaux1.fr K. Bourhis , Dr. T. Cardinal Institut de Chimie de la Matiere Condensee de Bordeaux University of Bordeaux 87 Avenue du Docteur Schweitzer, 33608 Pessac (France) Dr. Y. Deshayes Laboratoire de l ′ Integration du Materiau au Systeme University of Bordeaux 351 Cours de la Liberation, 33405 Talence (France)

Silver Clusters Embedded in Glass as a Perennial High Capacity Optical Recording Medium

The photoluminescence of Er3+ in borosilicate glass is strongly enhanced by the presence of silver Samples prepared by a combination of erbium ion implantation and Na+↔Ag+ ion exchange show an increase of the Er3+ excitation efficiency of up to a factor 70 when excited at 488 nm Excitation of Er3+ is possible over a broad wavelength range in the near ultraviolet and visible Our data suggest that absorption of light occurs at a silver ion/atom pair or similar defect, followed by energy transfer to Er3+ We can exclude that silver nanocrystals are part of the dominant excitation mechanism, neither via local field enhancement effects due to their surface plasmon resonance nor via absorption and subsequent energy transfer to Er3+

Silver as a sensitizer for erbium

The photoluminescence properties of a silicate glass coactivated with silver and erbium ions were studied. Absorption and photoluminescence spectra allowed to distinguish in the glasses several active species related to the silver, whose ratio depends on heat treatment and silver concentration. The broad emission of silver related species in the visible region of the spectrum has been studied in correlation with the nonresonant excitation of the erbium ions. The comparison of the excitation spectra of silver and erbium shows that the erbium ions are excited through radiative and nonradiative energy transfer from small silver aggregates.

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Mechanisms of Ag to Er energy transfer in silicate glasses: A photoluminescence study

Photoluminescent properties of glasses of the Ag 2 O–ZnO–P 2 O 5 system are reported. The compositions of the glasses are limited by the polyphosphate and diphosphate domain of this system. The phosphate structural units of the network former are deduced from Raman spectra. A comparison with the luminescent properties of crystallized silver phosphates of similar composition allows identification of two different emitting centers: isolated Ag + , Ag + –Ag + pairs, and a third center resulting from an Ag + –Zn 2+ interaction. The introduction of 1 mol% SiO 2 or Al 2 O 3 in these glasses leads to precipitation of silver particles, whose dimensions range from nanometers to micrometers, and to the appearance of luminescent centers (Ag 2 ) + detected around the micrometer particles by optical microscopy. We assume that these centers are an intermediate stage during the process of silver precipitation.

Silver aggregates in photoluminescent phosphate glasses of the `Ag2O–ZnO–P2O5' system

Spectroscopic properties of Ag+ ions in phosphate glasses of NaPO3−AgPO3 system

TeO2 forms stable glasses with Li2O and LiF in a large range of compositions (from 0.45 to 0.9 in molar ratio of TeO2). The ionic conductivity of these glasses is measured as a function of temperature and chemical composition by the complex impedance method (frequency range: 10−2 −104 Hz, temperature range: 100°C−Tg_. A parallel study by 7Li- and 19F-NMR spectroscopy allows identification of Li+ ions as the carriers responsible for the ionic conductivity of these solids. From the second moment of NMR signals, two different distributions of lithium are proposed: one in which Li+ ions are dispersed in Li2OTeO2 glasses and another one, in which Li+ and F− ions are associated in the network of LiFTeO2 glasses. These distributions are correlated with ionic conductivity results.

B Tanguy

Papers

Silver aggregates in photoluminescent phosphate glasses of the `Ag2O–ZnO–P2O5' system

Spectroscopic properties of Ag+ ions in phosphate glasses of NaPO3−AgPO3 system

Influence of ion distribution on the ionic conductivity of lithium tellurite glasses (Li2OTeO2 and LiFTeO2)

Crystal structure and luminescence properties of silver in AgM(PO3)3 (M = Mg, Zn, Ba) polyphosphates

Photoluminescent Metaphosphates Activated by Monovalent Silver