Search results for "Ge doping"
showing 5 items of 5 documents
Influence of the drawing process on the defect generation in multistep-index germanium-doped optical fibers
2009
International audience; Variation of germanium lone pair center (GLPC) concentration in germanosilicate multistep-index optical fibers and preforms was studied using confocal microscopy luminescence technique. The experimental results provide evidence that in the central core region ([Ge] ~11 wt. % ) of our specific canonical samples the ratio [GLPC]/[Ge] is five times larger in fiber than in preforms. The relative influence of the glass composition and of the drawing process on the generation efficiency of the GLPC defects that drive the glass photosensitivity is discussed. The radial distribution of these defects suggests a possible enhancement of the defect creation related to the intern…
Slow magnetic fluctuations and superconductivity in fluorine-doped NdFeAsO
2015
Among the widely studied superconducting iron-pnictide compounds belonging to the Ln1111 family (with Ln a lanthanide), a systematic investigation of the crossover region between the superconducting and the antiferromagnetic phase for the Ln = Nd case has been missing. We fill this gap by focusing on the intermediate doping regime of NdFeAsO(1-x)F(x) by means of dc-magnetometry and muon-spin spectroscopy measurements. The long-range order we detect at low fluorine doping is replaced by short-range magnetic interactions at x = 0.08, where also superconductivity appears. In this case, longitudinal-field muon-spin spectroscopy experiments show clear evidence of slow magnetic fluctuations that …
X-ray irradiation effects on a specific multistep Ge-doped fiber
2010
International audience; The study of point defects generation in optical fibers plays an important role with regards to their use and application in different domains. Their design and elaboration processes (dopants type, concentration, refractive index profile, drawing conditions...) govern their responses and more generally their radiation hardness [1]. In this work we investigated, the influence of 10 keV X-ray irradiations on a set of specific germanosilicate optical fibers elaborated from the same preform at different drawing conditions. The germanium doping levels along the fiber core diameter was specifically designed to follow a two-step distribution in order to highlight the Ge-con…
Origins of radiation-induced attenuation in pure-silica-core and Ge-doped optical fibers under pulsed x-ray irradiation
2020
We investigated the nature, optical properties, and decay kinetics of point defects causing large transient attenuation increase observed in silica-based optical fibers exposed to short duration and high-dose rate x-ray pulses. The transient radiation-induced attenuation (RIA) spectra of pure-silica-core (PSC), Ge-doped, F-doped, and Ge + F-doped optical fibers (OFs) were acquired after the ionizing pulse in the spectral range of [∼0.8–∼3.2] eV (∼1500–∼380 nm), from a few ms to several minutes after the pulse, at both room temperature (RT) and liquid nitrogen temperature (LNT). Comparing the fiber behavior at both temperatures better highlights the thermally unstable point defects contribut…
Photoluminescence properties of point defects in Ge-doped fibers and preforms
2008
International audience; The optical properties of Ge-related point defects are often the most important parameter for the performances of silica based optical fibers. On one side their presence is often detrimental for the light transmission, on the other side some defect typologies exhibit modifications under radiation exposure thus offering the peculiar property of photosensitivity that is exploited to build technologically relevant devices such as fiber Bragg gratings.