Bragg Gratings, Photosensitivity, and Poling in Glass Fibers and Waveguides: Applications and Fundamentals
Besides the study of inorganic oxide glasses using traditional MAS NMR of abundant nuclei (e.g. p... more Besides the study of inorganic oxide glasses using traditional MAS NMR of abundant nuclei (e.g. phosphorus, aluminium) the measurement of less common nuclei (e.g. Tin) provide important structural information. The experimental setup is more complicated due to the low natural abundance (8.5%), large chemical shift anisotropies (up to 1000 ppm), and long relaxation times of these nuclei (up to 500 s). Results will be presented for 119-Tin MAS NMR measurements of P2O5-SnO2 glasses. We have found a large change of Tg and phosphorus coordination at different Tin content.
In the present project, the transmission, fluorescence, energy transfer and laser efficiency shou... more In the present project, the transmission, fluorescence, energy transfer and laser efficiency should be studied depending on the composition of the laser host glass, the optical quality of the glass, the concentration of quencher ions (Fe, Cu, OH), the concentration of laser ions (Nd, Er) amd the concentration of sensitizer ions (Ce, Cr, Yb). For this purpose, fluoride-phosphate and phosphate glasses were melted, and the corresponding measurements were carried out on polished samples of such glasses. In a first part, the Nd"3"+ fluorescence and the energy transfer Ce"3"+ #-># Nd"3"+ and Cr"3"+ #-># Nd"3"+ have been characterized concerning the glass composition. By laser test under flashlamp pumping by 22% transparency of the back mirror, in Nd"3"+ doped fluoride-phosphate glasses with codoping of Ce"3"+ and/or Cr"3"+ ions a higher effeciency could be achieved than in Nd:YAG. Because of the appearan...
Current Opinion in Solid State and Materials Science, 2003
Abstract Fluoroaluminates are well known glass formers. Although their glass forming ability is l... more Abstract Fluoroaluminates are well known glass formers. Although their glass forming ability is low, it can be increased by doping with phosphates. Structure and properties depend mainly on the fluoride to phosphate ratio. In this review a number of recent developments in the use of these glasses for the fabrication of active laser and amplifier materials is discussed.
It has been developed low cost colorless and by NiO or/and CoO colored glasses with high uv-b-tra... more It has been developed low cost colorless and by NiO or/and CoO colored glasses with high uv-b-transmission based on silicates (BG, AR) and borosilicates (BK7, Duran), with low solarization and crystallization ability, high hydrolytical resistance, and mechanical strength, in a laboratory scale. The influence of iron and other impurities on the uv transmission, and the redox equilibria of different polyvalent ions in melts and glasses, dotation of reducing substances [Sn(II)-oxalate, sugar, carbon, metals] had been investigated. Thermodynamical data of polyvalent ions in the melts were determined by electrochemical measurements depending on the temperature (1500-700 C). A comparison with the values obtained by optical spectroscopy was done. The results of the laboratory research could be transfered to a pilot scale (380 kg). The chemical resistance was determined at different pH values. The best stability was in the acid region. Solarization was investigated by uv lamp and uv laser i...
Optical and Quantum Electronics - OPT QUANT ELECTRON, 1990
Sensitization of the fluorescence of Er3+ in fluoride phosphate glass containing up to 20 mol% ph... more Sensitization of the fluorescence of Er3+ in fluoride phosphate glass containing up to 20 mol% phosphates by codoping with Cr3+ and Yb3+ is shown. The low order of ligand field strength for Cr3+ (Dq/B=2.04) results in broad Cr3+ fluorescence overlapping the Yb3+ absorption. The electronic energy transfer efficiency approaches 100%. Deviations of donor decay from the Förster law are interpreted in terms of the inhomogeneously acceptor distribution. The electronic energy transfer efficiency of Yb3+ → Er3+ reaches a maximum value of 75% for glasses containing 20 mol% phosphates. The transfer is shown to be migrationally accelerated by means of GAF-LAF-FB theory. From Judd-Ofelt parameters a stimulated emission cross-section for the transition4I13/2 →4I15/2 of Er3+ of 6.2×10−20 cm2 is derived. The c.w. laser action of Er3+ by Cr3+ excitation and double-step energy transfer is shown. The output is tuned continuously from 1536 to 1596 nm. Flashlamp pumping is also shown.
For the X-ray irradiated fluoride-phosphate (FP) glasses with different phosphate content (from O... more For the X-ray irradiated fluoride-phosphate (FP) glasses with different phosphate content (from O to 20 mol%), a number of different radiation-induced defect centers (DC) were detected, which can be subdivided into three groups: phosphate, oxygen and fluorine related DC. The phosphate and oxygen related defects are paramagnetic, their optical absorptions were established by means of band separation and correlation to EPR signals. The non-paramagnetic fluorine-relat ed color centers (FD centers) were found for FP glasses with lower (< 2 mol%) phosphate content by means of band separation of induced spectra of optical absorption and annealing experiments. Nachweis von strahlungsinduzierten Defekten in Fluorid-Phosphatglasem mittels EPR und optischer Absorptions spektroskopie In rontgenbestra hlten Fluorid-Phosphatglasern (FP-Glasern) mit unterschiedlichem Phosphatgehal t (von 0 bis 20 Mol-%) wurde eine Vielzahl von strahlungsinduzierten Defekten gefunden, die mit unterschiedlichen...
Solarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transm... more Solarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transmission in the UV-B region (280 to 320 nm) was investigated for their use as container glasses in the solar disinfection of drinking water. The samples were coloured by doping with NiO or CoO. The influence of the Fe 3+ /Fe 2+ content and of the reducing component Sn 2+ was investigated on both the initial transmission of the glasses and the solarization. The samples were irradiated with a 1 kW Xe lamp and a XeCl excimer laser. The solarization depends on the glass matrix and is enhanced by colouring ions. The influence of Fe 3+ /Fe 2+ and Sn 2+ on the defect generation is different for glasses coloured with NiO than for those coloured with CoO. For the samples investigated it was possible to simulate the loss of transmission in the UV-B region due to long-time irradiation with sunlight by a laser experiment.
The influence of Eu3+, Eu2+ and Tb3+ ions on x-ray and ultra violet laser induced defects is exam... more The influence of Eu3+, Eu2+ and Tb3+ ions on x-ray and ultra violet laser induced defects is examined in a fluoride phosphate and an ultraphosphate glass. The defects are characterised by optical absorption, fluorescence and ESR spectroscopy Europium ions cause larger changes in the fluoride phosphate glass whereas terbium ions do in the ultraphosphate glass. Different mechanisms of defect formation are found for x-ray and ultraviolet excimer laser irradiation at 248 nm. X-ray irradiation induces valence changes of a part of the dopant ions into (Eu3+)-, (Eu2+)+ and (Tb3+)+ ions, respectively: By contrast, laser irradiation results in a very hst and complete photo-oxidation of Eu3+ but in a very slight photooxidation of Tb3+. Photoreduction of Eu3+ does not occur. Under x-ray irradiation, the dopants have a similar but small influence on the intrinsic defect formation. Extrinsic rare earth related defect centres replace intrinsic defects. On the contrary the laser induced photo-oxid...
Irradiation-induced defect formation is a common phenomenon in glasses. The influence of the two ... more Irradiation-induced defect formation is a common phenomenon in glasses. The influence of the two polyvalent ions cobalt and nickel was studied in several model glasses, two of those were fluoride-phosphate glasses. These studies were done in order to contribute to the ongoing research on solarization. Dopants and impurities may influence the intensity of intrinsic defects and may cause the evolution of additional extrinsic defects. Sample plates of high-purity glasses, undoped and doped with CoO and NiO, were irradiated by UV lamps and X-rays. The formed defect centers displayed absorption bands in the UV-VIS range, which were recorded by absorption spectroscopy. As many defect centers are paramagnetic, EPR spectra of the irradiated samples were taken. The newly found optical bands and EPR signals evolving in the irradiated glasses are in part characteristic of intrinsic defects, which are different types of electron and hole centers connected with phosphate groups. The other signal...
Abstract High purity fluoride phosphate glasses FP 10 (35 mol% AlF3, 30 CaF2, 15 SrF2, 10 MgF2, 1... more Abstract High purity fluoride phosphate glasses FP 10 (35 mol% AlF3, 30 CaF2, 15 SrF2, 10 MgF2, 10 Sr(PO3)2) with a large transmission range from the vacuum ultraviolet to the infrared were doped with polyvalent metal ions (Fe, Cu, Ce, Cr, Pb, Ni) in the ppm range. Their redox behaviour was investigated under normal and strong reducing melting conditions depending on temperature. Only one redox state was observed for Ni2+ and Pb2+. From the other metals, the following redox equilibria could be detected: Fe3+/Fe2+, Ce4+/Ce3+, Cu/Cu+/Cu0, Cr3+/Cr2+. A linear relation between the logCox/Cred and 1/T was found in the temperature range 900–1200 °C. In samples melted under normal conditions in air atmosphere, the higher redox state dominates but is strongly affected by the raw materials. By reducing melting conditions, the redox equilibrium could be shifted more than 99.5% to the lower oxidation state, Fe2+, Ce3+ and Cu+. Absorption, luminescence excitation and emission spectra were used detect Ce3+, Cu+, Pb2+ and Cr3+ to low quantities (
... SA Feller, M. Affatigato, DL Hogan, ND Nelson, C.Vira Physics Department, Coe College, Cedar ... more ... SA Feller, M. Affatigato, DL Hogan, ND Nelson, C.Vira Physics Department, Coe College, Cedar Rapids, IA 52402, USA YB Dimitriev, EM Gattef University of Chemical Technology and Metallurgy, 8 Boulevard Kliment Ohridski, 1756 Sofia, Bulgaria D. Ehrt Otto-Schott-Institut ...
Bragg Gratings, Photosensitivity, and Poling in Glass Fibers and Waveguides: Applications and Fundamentals
Besides the study of inorganic oxide glasses using traditional MAS NMR of abundant nuclei (e.g. p... more Besides the study of inorganic oxide glasses using traditional MAS NMR of abundant nuclei (e.g. phosphorus, aluminium) the measurement of less common nuclei (e.g. Tin) provide important structural information. The experimental setup is more complicated due to the low natural abundance (8.5%), large chemical shift anisotropies (up to 1000 ppm), and long relaxation times of these nuclei (up to 500 s). Results will be presented for 119-Tin MAS NMR measurements of P2O5-SnO2 glasses. We have found a large change of Tg and phosphorus coordination at different Tin content.
In the present project, the transmission, fluorescence, energy transfer and laser efficiency shou... more In the present project, the transmission, fluorescence, energy transfer and laser efficiency should be studied depending on the composition of the laser host glass, the optical quality of the glass, the concentration of quencher ions (Fe, Cu, OH), the concentration of laser ions (Nd, Er) amd the concentration of sensitizer ions (Ce, Cr, Yb). For this purpose, fluoride-phosphate and phosphate glasses were melted, and the corresponding measurements were carried out on polished samples of such glasses. In a first part, the Nd"3"+ fluorescence and the energy transfer Ce"3"+ #-># Nd"3"+ and Cr"3"+ #-># Nd"3"+ have been characterized concerning the glass composition. By laser test under flashlamp pumping by 22% transparency of the back mirror, in Nd"3"+ doped fluoride-phosphate glasses with codoping of Ce"3"+ and/or Cr"3"+ ions a higher effeciency could be achieved than in Nd:YAG. Because of the appearan...
Current Opinion in Solid State and Materials Science, 2003
Abstract Fluoroaluminates are well known glass formers. Although their glass forming ability is l... more Abstract Fluoroaluminates are well known glass formers. Although their glass forming ability is low, it can be increased by doping with phosphates. Structure and properties depend mainly on the fluoride to phosphate ratio. In this review a number of recent developments in the use of these glasses for the fabrication of active laser and amplifier materials is discussed.
It has been developed low cost colorless and by NiO or/and CoO colored glasses with high uv-b-tra... more It has been developed low cost colorless and by NiO or/and CoO colored glasses with high uv-b-transmission based on silicates (BG, AR) and borosilicates (BK7, Duran), with low solarization and crystallization ability, high hydrolytical resistance, and mechanical strength, in a laboratory scale. The influence of iron and other impurities on the uv transmission, and the redox equilibria of different polyvalent ions in melts and glasses, dotation of reducing substances [Sn(II)-oxalate, sugar, carbon, metals] had been investigated. Thermodynamical data of polyvalent ions in the melts were determined by electrochemical measurements depending on the temperature (1500-700 C). A comparison with the values obtained by optical spectroscopy was done. The results of the laboratory research could be transfered to a pilot scale (380 kg). The chemical resistance was determined at different pH values. The best stability was in the acid region. Solarization was investigated by uv lamp and uv laser i...
Optical and Quantum Electronics - OPT QUANT ELECTRON, 1990
Sensitization of the fluorescence of Er3+ in fluoride phosphate glass containing up to 20 mol% ph... more Sensitization of the fluorescence of Er3+ in fluoride phosphate glass containing up to 20 mol% phosphates by codoping with Cr3+ and Yb3+ is shown. The low order of ligand field strength for Cr3+ (Dq/B=2.04) results in broad Cr3+ fluorescence overlapping the Yb3+ absorption. The electronic energy transfer efficiency approaches 100%. Deviations of donor decay from the Förster law are interpreted in terms of the inhomogeneously acceptor distribution. The electronic energy transfer efficiency of Yb3+ → Er3+ reaches a maximum value of 75% for glasses containing 20 mol% phosphates. The transfer is shown to be migrationally accelerated by means of GAF-LAF-FB theory. From Judd-Ofelt parameters a stimulated emission cross-section for the transition4I13/2 →4I15/2 of Er3+ of 6.2×10−20 cm2 is derived. The c.w. laser action of Er3+ by Cr3+ excitation and double-step energy transfer is shown. The output is tuned continuously from 1536 to 1596 nm. Flashlamp pumping is also shown.
For the X-ray irradiated fluoride-phosphate (FP) glasses with different phosphate content (from O... more For the X-ray irradiated fluoride-phosphate (FP) glasses with different phosphate content (from O to 20 mol%), a number of different radiation-induced defect centers (DC) were detected, which can be subdivided into three groups: phosphate, oxygen and fluorine related DC. The phosphate and oxygen related defects are paramagnetic, their optical absorptions were established by means of band separation and correlation to EPR signals. The non-paramagnetic fluorine-relat ed color centers (FD centers) were found for FP glasses with lower (< 2 mol%) phosphate content by means of band separation of induced spectra of optical absorption and annealing experiments. Nachweis von strahlungsinduzierten Defekten in Fluorid-Phosphatglasem mittels EPR und optischer Absorptions spektroskopie In rontgenbestra hlten Fluorid-Phosphatglasern (FP-Glasern) mit unterschiedlichem Phosphatgehal t (von 0 bis 20 Mol-%) wurde eine Vielzahl von strahlungsinduzierten Defekten gefunden, die mit unterschiedlichen...
Solarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transm... more Solarization of colourless and coloured glasses of the type AR®, BK7® and DURAN® with high transmission in the UV-B region (280 to 320 nm) was investigated for their use as container glasses in the solar disinfection of drinking water. The samples were coloured by doping with NiO or CoO. The influence of the Fe 3+ /Fe 2+ content and of the reducing component Sn 2+ was investigated on both the initial transmission of the glasses and the solarization. The samples were irradiated with a 1 kW Xe lamp and a XeCl excimer laser. The solarization depends on the glass matrix and is enhanced by colouring ions. The influence of Fe 3+ /Fe 2+ and Sn 2+ on the defect generation is different for glasses coloured with NiO than for those coloured with CoO. For the samples investigated it was possible to simulate the loss of transmission in the UV-B region due to long-time irradiation with sunlight by a laser experiment.
The influence of Eu3+, Eu2+ and Tb3+ ions on x-ray and ultra violet laser induced defects is exam... more The influence of Eu3+, Eu2+ and Tb3+ ions on x-ray and ultra violet laser induced defects is examined in a fluoride phosphate and an ultraphosphate glass. The defects are characterised by optical absorption, fluorescence and ESR spectroscopy Europium ions cause larger changes in the fluoride phosphate glass whereas terbium ions do in the ultraphosphate glass. Different mechanisms of defect formation are found for x-ray and ultraviolet excimer laser irradiation at 248 nm. X-ray irradiation induces valence changes of a part of the dopant ions into (Eu3+)-, (Eu2+)+ and (Tb3+)+ ions, respectively: By contrast, laser irradiation results in a very hst and complete photo-oxidation of Eu3+ but in a very slight photooxidation of Tb3+. Photoreduction of Eu3+ does not occur. Under x-ray irradiation, the dopants have a similar but small influence on the intrinsic defect formation. Extrinsic rare earth related defect centres replace intrinsic defects. On the contrary the laser induced photo-oxid...
Irradiation-induced defect formation is a common phenomenon in glasses. The influence of the two ... more Irradiation-induced defect formation is a common phenomenon in glasses. The influence of the two polyvalent ions cobalt and nickel was studied in several model glasses, two of those were fluoride-phosphate glasses. These studies were done in order to contribute to the ongoing research on solarization. Dopants and impurities may influence the intensity of intrinsic defects and may cause the evolution of additional extrinsic defects. Sample plates of high-purity glasses, undoped and doped with CoO and NiO, were irradiated by UV lamps and X-rays. The formed defect centers displayed absorption bands in the UV-VIS range, which were recorded by absorption spectroscopy. As many defect centers are paramagnetic, EPR spectra of the irradiated samples were taken. The newly found optical bands and EPR signals evolving in the irradiated glasses are in part characteristic of intrinsic defects, which are different types of electron and hole centers connected with phosphate groups. The other signal...
Abstract High purity fluoride phosphate glasses FP 10 (35 mol% AlF3, 30 CaF2, 15 SrF2, 10 MgF2, 1... more Abstract High purity fluoride phosphate glasses FP 10 (35 mol% AlF3, 30 CaF2, 15 SrF2, 10 MgF2, 10 Sr(PO3)2) with a large transmission range from the vacuum ultraviolet to the infrared were doped with polyvalent metal ions (Fe, Cu, Ce, Cr, Pb, Ni) in the ppm range. Their redox behaviour was investigated under normal and strong reducing melting conditions depending on temperature. Only one redox state was observed for Ni2+ and Pb2+. From the other metals, the following redox equilibria could be detected: Fe3+/Fe2+, Ce4+/Ce3+, Cu/Cu+/Cu0, Cr3+/Cr2+. A linear relation between the logCox/Cred and 1/T was found in the temperature range 900–1200 °C. In samples melted under normal conditions in air atmosphere, the higher redox state dominates but is strongly affected by the raw materials. By reducing melting conditions, the redox equilibrium could be shifted more than 99.5% to the lower oxidation state, Fe2+, Ce3+ and Cu+. Absorption, luminescence excitation and emission spectra were used detect Ce3+, Cu+, Pb2+ and Cr3+ to low quantities (
... SA Feller, M. Affatigato, DL Hogan, ND Nelson, C.Vira Physics Department, Coe College, Cedar ... more ... SA Feller, M. Affatigato, DL Hogan, ND Nelson, C.Vira Physics Department, Coe College, Cedar Rapids, IA 52402, USA YB Dimitriev, EM Gattef University of Chemical Technology and Metallurgy, 8 Boulevard Kliment Ohridski, 1756 Sofia, Bulgaria D. Ehrt Otto-Schott-Institut ...
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