Synthesis, Ultrapurification and Analysis of LaF3 for Fluoride Optical Fibers

1986 ◽  
Vol 88 ◽  
Author(s):  
D. R. Gabbe ◽  
R. C. Folweiler ◽  
F. X. Pink
Keyword(s):  
Neutron Activation Analysis ◽  
Optical Fibers ◽  
Ionic Radius ◽  
Concentration Profiles ◽  
Zone Refining ◽  
Impurity Segregation ◽  
A Value ◽  
Coefficient Versus ◽  
Rare Earth Impurities ◽  
Measured Distribution

ABSTRACTLanthanum chloride was synthesized by reacting La2O3 with CCl4. Purification carried out by zone refining resulted in reduction of Nd and Eu concentrations by at least a factor of 103. Impurity segregation coefficients were calculated from the concentration profiles in the charge measured by neutron activation analysis. Values of 0.85, 0.5, and 0.15 were found for Ce, Nd and Eu while a value of 0.65 was obtained for Pr from a plot of measured distribution coefficient versus ionic radius. These results show the feasibility of removing rare earth impurities to the ppb level from LaCl3. After purification, LaC13 is converted to LaF3

scholarly journals Optimization of Fiber Bragg Gratings Inscribed in Thin Films Deposited on D-Shaped Optical Fibers

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4056
Author(s):  
José Javier Imas ◽  
Carlos R. Zamarreño ◽  
Ignacio del Villar ◽  
Ignacio R. Matías
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Optical Fibers ◽  
Flat Surface ◽  
Sno2 Thin Film ◽  
Thin Film Thickness ◽  
A Value ◽  
Surrounding Refractive Index ◽  
Reflected Power ◽  
Fabrication Parameters

A fiber Bragg grating patterned on a SnO2 thin film deposited on the flat surface of a D-shaped polished optical fiber is studied in this work. The fabrication parameters of this structure were optimized to achieve a trade-off among reflected power, full width half maximum (FWHM), sensitivity to the surrounding refractive index (SRI), and figure of merit (FOM). In the first place, the influence of the thin film thickness, the cladding thickness between the core and the flat surface of the D-shaped fiber (neck), and the length of the D-shaped zone over the reflected power and the FWHM were assessed. Reflected peak powers in the range from −2 dB to −10 dB can be easily achieved with FWHM below 100 pm. In the second place, the sensitivity to the SRI, the FWHM, and the FOM were analyzed for variations of the SRI in the 1.33–1.4 range, the neck, and the thin-film thickness. The best sensitivities theoretically achieved for this device are next to 40 nm/RIU, while the best FOM has a value of 114 RIU−1.

Rare-earth partition between allanite and glass in the obsidian of Sandy Braes, Northern Ireland

1981 ◽  
Vol 44 (334) ◽  
pp. 157-160 ◽  
Author(s):  
C. K. Brooks ◽  
P. Henderson ◽  
J. G. Rønsbo
Keyword(s):  
Rare Earth ◽  
Neutron Activation Analysis ◽  
Instrumental Neutron Activation Analysis ◽  
Activation Analysis ◽  
Northern Ireland ◽  
Partition Coefficients ◽  
Ionic Radius ◽  
Major Elements ◽  
Steep Slope ◽  
Eu Anomaly

AbstractAllanite phenocrysts and co-existing glass from the perlitic obsidian of Sandy Braes have been analysed for nine rare earths (RE), uranium, and thorium by instrumental neutron activation analysis and for the major elements by electron microprobe. The chondritenormalized RE plot for the allanite shows a steep slope with a negative Eu anomaly. Allanite/glass partition coefficients show a smooth variation with ionic radius (except for Eu), the variation spanning two orders of magnitude. The partitioning behaviour, which is distinct from that shown by the RE in sphene, apatite, and zircon, can be explained by the allanite structure. The pronounced affinity of the light RE for allanite makes this an important mineral in considerations of RE concentrations during the evolution of granitic liquids.

Quantitative Determination of Bi Segregation at Grain Boundaries in Cu Bicrystals

1997 ◽  
Vol 3 (S2) ◽  
pp. 535-536
Author(s):  
U. Alber ◽  
H. Müllejans ◽  
M. Rühle
Keyword(s):  
Electron Beam ◽  
Grain Boundaries ◽  
Primary Electron ◽  
Atomic Scale ◽  
Beam Diameter ◽  
Primary Electron Beam ◽  
Impurity Segregation ◽  
A Value ◽  
Bi Segregation ◽  
Beam Broadening

Impurity segregation at grain boundaries (GB) can be detected by EDS in a dedicated STEM. Quantification of the segregation requires not only quantification of the spectra but also consideration of the geometry of the experiment. Our aim was to obtain a value which characterises only the segregation of the impurity and is independent of experimental parameters. The problem is that the specimen composition at the GB is extremely inhomogeneous on an atomic scale in the case of Bi segregation at GBs in Cu. The analysed volume which is defined by the irradiated area and the beam broadening of the primary electron beam inside the specimen contains the interfacial plane as well as neighbouring bulk Cu. One approach is to put the focussed primary electron beam on the interface which is aligned edge on and acquire a spectrum. Both the primary beam diameter and the beam broadening inside the specimen have to be known.

Performance evaluation of a multiple optical link FSO–FSO

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mohammed Larbi Tayebi ◽  
Amina Djir ◽  
Fatiha Meskine
Keyword(s):  
Quality Factor ◽  
Optical Fibers ◽  
Large Scale ◽  
Atmospheric Conditions ◽  
Space Optics ◽  
Slowing Down ◽  
A Value ◽  
Operating Distance ◽  
Quality Factor Q ◽  
Attenuation Values

AbstractFree-space optics (FSO) connects two distant points by a simple light beam. Currently, this technique is a complement to radio frequency systems and those based on optical fibers. However, its large-scale deployment is slowing down due to major drawbacks such as the short operating distance and its great vulnerability to atmospheric conditions. In this article, and in order to increase the connection distance of the FSO systems and maintaining an acceptable signal quality, we inserted in the transmission channel: a receiver and a transmitter that retransmit the received signal. We have chosen two weather situations. The attenuation values used are 85 dB/km and 170 dB/km. They represent two different fog densities. For an attenuation of 85 dB/km, the quality factor Q degrades and goes from the value 44.50 to 2.60 when the distance goes from 90 to 180 m. With the proposed technique, the quality factor has improved significantly since we obtained a value that is equal to 29.82 instead of 2.60 at the overall distance of 180 m. On the other hand, we increased the distance until we obtained a quality factor around 2.5. The distance obtained is equal to 360 m, which is twice the initial distance.

Effect of multi-pass, zone length and translation rate on impurity segregation during zone refining of tellurium

2006 ◽  
Vol 60 (15) ◽  
pp. 1875-1879 ◽  
Author(s):  
D.S. Prasad ◽  
N.R. Munirathnam ◽  
J.V. Rao ◽  
T.L. Prakash
Keyword(s):  
Zone Refining ◽  
Translation Rate ◽  
Zone Length ◽  
Impurity Segregation
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