0000000001179235
AUTHOR
P. Paillet
showing 19 related works from this author
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…
Radiation effects on silica-based preforms and optical fibers-I: Experimental study with canonical samples
2008
International audience; Prototype samples of preforms and associated fibers have been designed and fabricated through MCVD process to investigate the role of fluorine (F) and germanium (Ge) doping elements on the radiation sensitivity of silica-based glasses. We characterized the behaviors of these canonical samples before, during and after 10 keV X-ray irradiation through several spectroscopic techniques, to obtain global information (in situ absorption measurements, electron paramagnetic resonance) or spatially-resolved information (confocal microscopy, absorption and luminescence on preform). These tests showed that, for the Ge-doped fiber and in the 300–900 nm range, the radiation-induc…
Steady state γ-ray radiation effects on Brillouin fiber sensors
2015
International audience; Brillouin optical time-domain analysis (BOTDA) sensors offer remarkable advantages for the surveillance of the planned French deep geological radioactive wastes repository, called Cigéo1,2. In this work we study the performances of Brillouin distributed sensors in harsh environment. We evaluate the radiation tolerance of different sensor classes and their responses evolution during γ-ray exposition with 1kGy/h dose rate (to reach ~0.2MGy) and after 1, 3, 6 and 10 MGy accumulated doses. Measurements on strained Ge-doped SMF are reported to highlight the variation on Brillouin scattering proprieties, both intrinsic frequency position of Brillouin shift and its dependen…
Hydrogen and radiation induced effects on performances of Raman fiber-based temperature sensors
2014
International audience; Raman Distributed Temperature Sensors (RDTS) offer exceptional advantages for the monitoring of the envisioned French deep geological repository for nuclear wastes, called Cigéo. Here, we present experimental studies on how the performances of RDTS evolve in harsh environments like those associated with H2 or g-rays. Both of them are shown to strongly affect the temperature measurements made with RDTS. We showed that by adapting the characteristics of the used fiber for the sensing, we could limit its degradation but that additional hardening by system studies will have to be developed before integration of RDTS in Cigéo.
Raman based distributed fiber optic temperature sensors for structural health monitoring in radiation environment
2015
Raman distributed temperature sensor (RDTS) measurements were performed during γ-radiation on three different classes of standard multimode fibers (pure, Ge-doped and F-doped). The sensor response is affected by the radiation induced attenuation phenomena leading to errors in the temperature measurements. The amplitude of this error strongly depends on the fiber type and the irradiation conditions. These results are promising in view of the integration of these RDTS into the deep geological repository for radioactive waste.
Combined High Dose and Temperature Radiation Effects on Multimode Silica-Based Optical Fibers
2013
International audience; We investigate the response of Ge-doped, P-doped, pure-silica, or Fluorine-doped fibers to extreme environments combining doses up to MGy(SiO $_{{{2}}}$) level of 10 keV X-rays and temperatures between 25 C and 300 C . First, we evaluate their potential to serve either as parts of radiation tolerant optical or optoelectronic systems or at the opposite, for the most sensitive ones, as punctual or distributed dosimeters. Second, we improve our knowledge on combined ionizing radiations and temperature (R&T) effects on radiation-induced attenuation (RIA) by measuring the RIA spectra in the ultraviolet and visible domains varying the R&T conditions. Our results reveal the…
Radiation effects on silica-based preforms and optical fibers-II: Coupling ab initio simulations and experiments
2008
International audience; Abstract—Experimental characterization through electron paramagnetic resonance (EPR) and confocal luminescence microscopy (CML) of a Ge-doped glass (preform and fiber) reveals the generation of several point defects by 10 keV X-ray radiation-induced attenuation: GeE', Ge(1), Ge(2), and Ge-ODC. The generation mechanisms of Ge-ODC and charged defects like GeE' centers are studied through ab initio simulation. Our calculations used a 108 atom supercell with a glass composition comparable to the Ge-doped core or to the pure-silica cladding of the canonical sample. The large size of our cell allows us to study the influence of the local environment surrounding the X-ODC d…
On-Line Characterization of Gamma Radiation Effects on Single-Ended Raman Based Distributed Fiber Optic Sensor
2016
We report distributed temperature measurements based on Raman scattering performed during steady state $\gamma $ -ray irradiation at a dose rate of 1 kGy( ${\rm SiO}_{2}$ )/h and up to a total ionizing dose (TID) of $\sim 0.1\ \hbox{MGy}$ . We characterize on-line the evolution of the performances of a single-ended Raman distributed temperature sensor (RDTS) during the $\gamma $ -ray exposure of different classes of commercial multimode fibers (MMFs) acting as the sensing element. RDTS is influenced by the radiation-induced attenuation (RIA) phenomena leading to both large errors in the temperature measurements and a diminution of the useful sensing length. The amplitude of the radiation-in…
Effect of irradiation temperature on the radiation induced attenuation of Ge-doped fibers
2016
International audience; The UV-visible radiation induced attenuation (RIA) was studied in Ge-doped optical fibers, during X-ray (10 keV) irradiations at different temperatures. By comparing the spectra recorded in dissimilarly irradiated samples we evidenced the impact of the irradiation temperature. In details, we highlighted that, from a certain dose, increasing the temperature the RIA decreases for wavelengths lower than 470 nm, whereas at higher wavelengths the RIA depends only on the dose. Such findings suggest that it is possible to distinguish the irradiation temperature by comparing the signal at two different wavelengths. From the microscopic point of view, it appears that the RIA …
Transient Radiation Responses of Optical Fibers: Influence of MCVD Process Parameters
2012
International audience; A dedicated set of fibers elaborated via the Modified Chemical Vapor Deposition (MCVD) technique is used to study the influence of composition and drawing parameters on their responses to an X-ray pulse representative of the radiation environments associated with Megajoule class lasers. These canonical fibers were designed to highlight the impact of these parameters on the amplitude and kinetics of the transient pulsed X-ray Radiation Induced Attenuation (RIA) at room temperature. From preforms differing by their core composition, three optical fibers were elaborated by varying the tension and speed during the drawing process. No or only slight RIA change results fro…
Development of a Temperature Distributed Monitoring System Based On Raman Scattering in Harsh Environment
2014
Raman Distributed Temperature Sensors (RDTSs) offer exceptional advantages to monitor the envisioned French deep geological repository for nuclear wastes, called Cigeo. Both $\gamma $ -ray and hydrogen release from nuclear wastes can strongly affect the temperature measurements made with RDTS. We present experimental studies on how the performances of RDTS evolve in harsh environments like those associated with $\gamma $ -rays or combined radiations and ${{\rm H}_2}$ release. The response of two standard and one radiation tolerant multimode fibers (MMFs) are investigated. In all fibers the differential induced attenuation between Stokes and anti-Stokes signal, ${({{\alpha _{\rm AS}} - {\alp…
Coupled theoretical and experimental studies for the radiation hardening of silica-based optical fibers
2014
International audience; We applied theoretical and experimental spectroscopy tools to ad hoc silica-based "canonical" samples to characterize the influence of several dopants and of some drawing process parameters on their radiation sensitivities. We present in this paper, the recent advances and results occurring from our coupled approach. On the experimental side, we studied the doping influence on the response of optical fibers and showed that changing the drawing parameters has a negligible influence on the fiber response in the case of specialty fibers. We focus mainly on the ${rm SiE}^prime$ defect that is observed through Electron Paramagnetic Resonance (EPR) measurements in all cano…
Irradiation temperature influence on the in-situ measured radiation induced attenuation of Ge-doped fibers
2016
International audience; We report an experimental investigation on the radiation induced attenuation (RIA) in the ultraviolet-visible domain for Ge-doped optical fibers, during X-rays (10 keV) exposure at different temperatures. The objective is to characterize the impact of the irradiation temperature on the RIA levels and kinetics. Our data highlight that for dose exceeding 1 kGy(SiO2) the RIA spectrum changes with the irradiation temperature. In particular, for wavelengths below 470 nm the RIA depends both on the dose and on the irradiation temperature, whereas at higher wavelengths the RIA depends only on the dose. From the microscopic point of view the origin of this behavior is explai…
Radiation tolerant fiber Bragg gratings for high temperature monitoring at MGy dose levels
2014
International audience; We report a method for fabricating fiber Bragg gratings (FBG) resistant to very severe environments mixing high radiation doses (up to 3 MGy) and high temperatures (up to 230 degrees C). Such FBGs have been written in two types of radiation resistant optical fibers (pure-silica and fluorine-doped cores) by exposures to a 800 nm femtosecond IR laser at power exceeding 500 mW and then subjected to a thermal annealing treatment of 15 min at 750 degrees C. Under radiation, our study reveals that the radiation induced Bragg wavelength shift (BWS) at a 3 MGy dose is strongly reduced compared to responses of FBGs written with nonoptimized conditions. The BWS remains lower t…
Radiation Response of Ce-Codoped Germanosilicate and Phosphosilicate Optical Fibers
2016
We report an experimental investigation on the effects of Ce-codoping in determining the radiation response of germanosilicate and phosphosilicate Optical Fibers (OFs) in the UV-Visible domain and up to doses of $1~\hbox{MGy}({\rm SiO}_{2})$ . We show that the addition of Ce strongly impacts the Radiation Induced Attenuation (RIA) of both types of fibers. In the first case the radiation induced losses increase, whereas in the second one decrease. By combining the online RIA measurements with the Electron Paramagnetic Resonance (EPR) ones, we are able to infer the basic microscopic mechanisms taking place under irradiation, which involve the cerium codopant and some of the known Ge-related o…
Transient and Steady-State Radiation Response of Phosphosilicate Optical Fibers: Influence of H2 Loading
2019
The radiation response of a phosphorus-doped multimode optical fiber is investigated under both transient (pulsed X-rays) and steady-state ( $\gamma $ - and X-rays) irradiations. The influence of a H2 preloading on the fiber radiation-induced attenuation (RIA) in the 300–2000-nm wavelength range has been characterized. To better understand the impact of this treatment, online behaviors of fiber samples containing different amounts of gas are compared from glass saturation (100%) to less than 1%. In addition to these in situ experiments, additional postirradiation spectroscopic techniques have been performed such as electron paramagnetic resonance or luminescence measurements to identify the…
Direct evidence of secondary recoiled nuclei from high energy protons
2008
The production of secondary recoiled particles from interactions between high energy protons and microelectronics devices was investigated. By using NAND Flash memories, we were able to directly obtain analog information on recoil characteristics. While our results qualitatively confirm the role of nuclear reactions, in particular of those with tungsten, a quantitative model based on Monte Carlo and device-level simulations cannot describe the observed results in terms of recoils from proton-W reactions. © 2006 IEEE.
Radiation and Hydrogen-Loading effects on Raman fiber-based temperature sensors
2013
We present experimental studies on how Raman based temperature sensors undergone two different treatments: gamma-radiation and H-loading. Unfortunately, gamma radiation and hydrogen release in harsh nuclear environment can affect the temperature measurements based on this technology of sensor, limiting the sensor performances. Moreover, the Raman device response in both cases changes with the different classes of multimode fibers that are used by the engineers.
Radiation Effects on Silica-Based Preforms and Optical Fibers - II: Coupling Ab Initio Simulations and Experiments
2008
International audience; Both experimental and theoretical approaches are combined to study the nature of precursor sites and radiation-induced point defects in pure and germanium-doped amorphous silica-based glasses.