0000000000042864

AUTHOR

K. Medjahdi

showing 3 related works from this author

UV-Photoinduced Defects In Ge-Doped Optical Fibers

2005

We investigated the effect of continuous-wave (cw) UV laser radiation on single-mode Ge-doped H2- loaded optical fibers. An innovative technique was developed to measure the optical absorption (OA) induced in the samples by irradiation, and to study its dependence from laser fluence. The combined use of the electron spin resonance (ESR) technique allowed the structural identification of several radiation-induced point defects, among which the Ge(1) (GeO4 -) is found to be responsible of induced OA in the investigated spectral region.

Condensed Matter - Materials ScienceMaterials scienceOptical fiberbusiness.industryDopingMaterials Science (cond-mat.mtrl-sci)FOS: Physical sciencesDisordered Systems and Neural Networks (cond-mat.dis-nn)RadiationCondensed Matter - Disordered Systems and Neural NetworksFluenceCrystallographic defectoptical fibers radiation effects radiation-induced attenuationlaw.inventionlawOptoelectronicsIrradiationAbsorption (electromagnetic radiation)businessElectron paramagnetic resonance
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Ultraviolet-induced paramagnetic centers and absorption changes in singlemode Ge-doped optical fibers

2009

We investigated the laser-energy-density dependence of absorption changes and paramagnetic centers induced by a cw Ar+ laser operating at 5.1 eV, in both unloaded and H-2-loaded single mode Ge-doped optical fibers. The induced absorption is measured in the blue and near ultraviolet spectral range by using the 3.1 eV photoluminescence, ascribed to Ge lone pair center (GLPC), as an in situ probe source. We find that the Ge (1) center (GeO4-) is induced upon UV exposure by electron trapping on GeO4 precursors, where the free electrons are most likely produced by ionization of GLPC. Ge (1) is responsible of optical transmission loss of the fiber in the investigated range. Hydrogen loading stron…

Optical fiberMaterials sciencePhotoluminescence060.2290 160.4670 160.4760 300.1030 300.2140 300.6370 300.636002 engineering and technologymedicine.disease_cause01 natural sciences7. Clean energyAbsorptionMECHANISMSlaw.inventionEmissionParamagnetismOpticslawIonization0103 physical sciencesmedicineSILICA010306 general physicsSpectroscopyAbsorption (electromagnetic radiation)defectsESR[PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics]business.industryDopingGEO2-SIO2 GLASSESPHOTOSENSITIVITY021001 nanoscience & nanotechnologyAtomic and Molecular Physics and OpticsIRRADIATIONFibersDEFECT CENTERSSIO2 GLASSLUMINESCENCEKRF EXCIMER-LASER0210 nano-technologybusinessUltravioletGENERATIONOptics Express
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Role of diffusing molecular hydrogen on relaxation processes in Ge-doped glass

2007

Temperature dependencies of steady-state and time-resolved photoluminescence (PL) from triplet state at 3.1 eV and singlet state at 4.2 eV ascribed to the twofold-coordinated Ge have been measured in unloaded and H2-loaded Ge-doped silica samples under 5.0 eV excitation in the 10–310 K range. Experimental evidences indicate that diffusing molecular hydrogen (H2) depopulates by a collisional mechanism the triplet state, decreasing both its lifetime of about 14% and the associated triplet PL intensity, whereas those of the singlet are insensitive to the presence of H2.

PhotoluminescenceChemistryDopingRelaxation (NMR)Condensed Matter PhysicsPhotochemistryMolecular physicsElectronic Optical and Magnetic MaterialsHydrogen in glassOptical spectroscopyLuminescenceGermanatesSinglet fissionMaterials ChemistryCeramics and CompositesSinglet stateTriplet stateSpectroscopyExcitationJournal of Non-Crystalline Solids
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