Effects of Defect Modification and Reduction Techniques on the Radiation Sensitivity of Optical Fibers

1986 ◽  
Vol 88 ◽  
Author(s):  
T. Wei ◽  
M. P. Singh ◽  
W. J. Miniscalco ◽  
J. A. Wall
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Measurement Techniques ◽  
Inverse Correlation ◽  
Radiation Sensitivity ◽  
Interfacial Stress ◽  
Γ Irradiation ◽  
Graded Index ◽  
Radiation Induced ◽  
Induced Defects

ABSTRACTWe have investigated the relationship of precursor defects in as-drawn optical fiber to glass composition and processing conditions in order to understand the radiation sensitivity of doped-core optical fiber. Techniques are reported for improving the radiation hardness of graded-index multimode fibers through reducing the concentration of doping- and processing-induced defects as well as modifying the residual defects in as-drawn fiber. Significant decreases in radiation-induced loss have been observed for fibers pretreated with hydrogen. An investigation of the role of drawing-induced defects indicates that a lower draw temperature produces slightly harder fiber. A study of core/clad interfacial stress revealed that such stress does not play a major role in radiation sensitivity.Measurement techniques included in situ loss measurements at 850 nm and spectral loss measurements before and after -γ irradiation. In addition, photoluminescence proved to be an effective tool for characterizing specific defect centers. It was found for Ge/P-codoped fibers that the luminescence band at 650 nm attributed to drawing/radiation induced centers has an inverse correlation with induced loss. Previously unreported emission bands have been observed, including one at 720 nm which may be related to fluorine doping.

Radiation-Induced-Defects Localization in Single-Mode Optical Fibers

2005 ◽  
Vol 480-481 ◽  
pp. 329-332 ◽  
Author(s):  
Sylvain Girard ◽  
A. Boukenter ◽  
Y. Ouerdane ◽  
J.-P. Meunier
Keyword(s):  
Optical Fibers ◽  
Single Mode ◽  
Wavelength Dependence ◽  
Radiation Sensitivity ◽  
Color Centers ◽  
Strong Interactions ◽  
Radiation Induced ◽  
Different Color ◽  
Induced Defects

We studied the defects at the origins of the permanent radiation-induced attenuation in four g-rays irradiated single-mode germanosilicate optical fibers (~1 MeV; 1.2 kGy; 0.3 Gy/s) in the spectral range 400 - 1700 nm. We determined the wavelength dependence of the following cladding codopant influences: germanium (0.3 %), phosphorus (0.3 %), fluorine (0.3 %) on the germanosilicate (13 %) fiber radiation responses. We identified some of the different color centers produced by g-rays and we evaluated their localization in the fiber cross-section through the determination of the radial distribution of the radiation-induced absorption at 633 nm. We also evidenced the strong interactions between these three codopants. In particular, our results showed that the properties of the phosphorus-related color centers, which mainly determine the fiber infrared radiation sensitivity, are strongly influenced by the germanium- and fluorine-codoping.

Formation of Drawing- or Radiation-Induced Defects in Germanium-Doped Silica Core Optical Fiber

1994 ◽  
Vol 33 (Part 2, No. 2B) ◽  
pp. L233-L234 ◽  
Author(s):  
Yoshinori Hayashi ◽  
Yuki Okuda ◽  
Hisamitsu Mitera ◽  
Keizo Kato
Keyword(s):  
Optical Fiber ◽  
Radiation Induced ◽  
Silica Core ◽  
Induced Defects

Radiation-induced defects in montebrasite: An electron paramagnetic resonance study of O – hole and Ti3+ electron centers

2020 ◽  
Vol 105 (7) ◽  
pp. 1051-1059
Author(s):  
José R. Toledo ◽  
Raphaela de Oliveira ◽  
Lorena N. Dias ◽  
Mário L.C. Chaves ◽  
Joachim Karfunkel ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Irradiation ◽  
Color Centers ◽  
Hydroxyl Groups ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Radiation Induced ◽  
Induced Defects ◽  
Electron Paramagnetic ◽  
Hole Centers

Abstract Montebrasite is a lithium aluminum phosphate mineral with the chemical formula LiAlPO4(Fx,OH1–x) and considered a rare gemstone material when exhibiting good crystallinity. In general, montebrasite is colorless, sometimes pale yellow or pale blue. Many minerals that do not have colors contain hydroxyl ions in their crystal structures and can develop color centers after ionization or particle irradiation, examples of which are topaz, quartz, and tourmaline. The color centers in these minerals are often related to O− hole centers, where the color is produced by bound small polarons inducing absorption bands in the near UV to the visible spectral range. In this work, colorless montebrasite specimens from Minas Gerais state, Brazil, were investigated by electron paramagnetic resonance (EPR) for radiation-induced defects and color centers. Although γ irradiation (up to a total dose of 1 MGy) did not visibly modify color, a 10 MeV electron irradiation (80 MGy) induced a pale greenish-blue color. Using EPR, O− hole centers were identified in both γ- or electron-irradiated montebrasite samples showing superhyperfine interactions with two nearly equivalent 27Al nuclei. In addition, two different Ti3+ electron centers were also observed. From the γ irradiation dose dependency and thermal stability experiments, it is concluded that production of O− hole centers is limited by simultaneous creation of Ti3+ electron centers located between two equivalent hydroxyl groups. In contrast, the concentration of O− hole centers can be strongly increased by high-dose electron irradiation independent of the type of Ti3+ electron centers. From detailed analysis of the EPR angular rotation patterns, microscopic models for the O− hole and Ti3+ electron centers are presented, as well as their role in the formation of color centers discussed and compared to other minerals.

Effect of γ-Irradiation on the Mechanical Properties of Al-Cu Alloy

2006 ◽  
Vol 251-252 ◽  
pp. 105-110 ◽  
Author(s):  
M. Abo-Elsoud ◽  
H. Ismail
Keyword(s):  
Quantitative Information ◽  
Irradiation Effect ◽  
Γ Irradiation ◽  
Cu Content ◽  
Cu Alloy ◽  
Hardness Tests ◽  
Radiation Induced ◽  
Induced Defects ◽  
Aging Hardening ◽  
Kinetics Of

SEM observations and Vickers-hardness tests were performed to identify the irradiation effects. γ- irradiation effect during the aging hardening process can be explained depending on the composition of the alloy and is used to derive quantitative information on the kinetics of the transformation precipitates. Increasing the Cu content of an Al-Cu alloy can improve the aging hardness. The present results of hardness behavior with SEM observations of surveillance specimens at different doses suggest that the radiation-induced defects are probably complex valance-solute clusters. These clusters act as nuclei for the precipitation of θ-Al2Cu type. This can be effectively utilized to study the systematic of nucleation of precipitates at vacancy-type defects. γ-irradiation probably play the key role in defects responsible for material strengthening and embrittlement.

EFFECT OF γ-IRRADIATION ON THE MECHANICAL PROPERTIES OF AL–CU ALLOY

2006 ◽  
Vol 13 (06) ◽  
pp. 773-777 ◽  
Author(s):  
M. ABO-ELSOUD ◽  
H. ISMAIL ◽  
MAGED S. SOBHY
Keyword(s):  
Quantitative Information ◽  
Irradiation Effect ◽  
Γ Irradiation ◽  
Cu Content ◽  
Cu Alloy ◽  
Hardness Tests ◽  
Radiation Induced ◽  
Induced Defects ◽  
Aging Hardening ◽  
Kinetics Of

SEM observations and Vickers hardness tests were performed to identify the irradiation effects. γ-irradiation effect during the aging hardening process can be explained depending on the composition of the alloy and is used to derive quantitative information on the kinetics of the transformation precipitates. Increasing the Cu content of an Al – Cu alloy can improve the aging hardness. The present results of the hardness behavior, with SEM observations of surveillance specimens at different doses, suggest that the radiation-induced defects are probably complex valence-solute clusters. These clusters act as nuclei for the precipitation of θ- Al 2 Cu type. This can be effectively utilized to study the systematics of nucleation of precipitates at vacancy-type defects. γ-irradiation probably plays the key role in defects responsible for material strengthening and embrittlement.

Lensed Plastic Optical Fiber with a Convexo-Concave Fiber Endface for Coupling Laser Diodes With Plastic Optical Fiber

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Yih-Tun Tseng ◽  
Shu-Ming Chang ◽  
Sheng-He Huang ◽  
Wood-Hi Cheng
Keyword(s):  
Optical Fiber ◽  
Light Source ◽  
Optical Fibers ◽  
Transmission Rate ◽  
Coupling Efficiency ◽  
Small Diameter ◽  
Plastic Optical Fiber ◽  
Graded Index ◽  
Coupling Laser ◽  
Working Distance

This work presents a novel lensed plastic optical fiber (POF), efficiently coupled with a light source. A convexo-concave plastic lens (CCPL) was bound to a flat-end plastic optical fiber using laser transmission welding (LTW) to form a convexo-concave-shaped fiber endface (CCSFE). The novel lensed plastic optical fiber has a longer working distance and a higher coupling efficiency than conventional lensed plastic optical fibers. 850 nm fiber is often used in high-power 2.5 Gb/s transmission rate. Experimental POF is perfluorinated POF, 62.5–500 μm diameter, 850∼1300 μm wavelength, 10 dB/km power loss rate, 2.5 Gb/s transmission rate. Because of the small diameter of POF, it is difficult to couple between the light source and POF. Therefore, it is important to develop a lensed fiber structure to increase the coupling efficiency. Experiments indicate that the coupling efficiency between a laser diode at a wavelength of 850 nm and a graded-index POF is as high as 85% with a long working distance of 250 μm. The measured tolerance, in relation to the lateral and vertical displacements and tilt, are satisfactory for practical active alignment.

scholarly journals Structural and Optical Modifications in the BaO-ZnO-LiF-B2O3-Yb2O3 Glass System after γ-Irradiation

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6955
Author(s):  
Nimitha S. Prabhu ◽  
Hiriyur Mallaiah Somashekarappa ◽  
M. I. Sayyed ◽  
Hamid Osman ◽  
Sultan Alamri ◽  
...  
Keyword(s):  
Trap Depth ◽  
Structural Rearrangement ◽  
Glass System ◽  
Γ Irradiation ◽  
Oxygen Hole ◽  
Spin Resonance ◽  
Before And After ◽  
Radiation Induced ◽  
The Fourier Transform ◽  
Induced Defects

A Yb3+-doped borate glass system was examined for the structural and optical modifications after γ-irradiation. Among the studied 10BaO-20ZnO-20LiF-(50-x)B2O3-xYb2O3 (x = 0.1, 0.5, 0.7, and 1.0 mol%) glasses, the 10BaO-20ZnO-20LiF-49.9B2O3-0.1Yb2O3 glass showed the highest thermoluminescence intensity, trap density, and trap depth. The glass was irradiated with the optimum γ-dose of 1 kGy towards the analysis of radiation-induced defects. The amorphous nature was preserved before and after irradiation. The glass density slightly increased after irradiation. The structural rearrangement was evident from the Fourier transform infrared spectroscopy by the appearance and disappearance of some bonds after γ-irradiation. The transformation of [BO4] units into [BO3] units and non-bridging oxygens was deduced. The color of the glass darkened after irradiation and the optical absorption intensity enhanced between 250 and 700 nm. The optical bandgap reduced and Urbach energy increased upon γ-dose exposure. The electron spin resonance of the irradiated glass exhibited two signals at g = 2.0167 and g = 1.9938, corresponding to the non-bridging oxygen hole center and Boron E’-center, respectively.

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