This work presents results of test series, performed for earlier on designed and successfully fabricated silica few-mode microstructured optical fibers (MOF) with six GeO2-doped cores, induced twisting 50 revolutions per meter, typical “telecommunication” outer diameter 125 µm, core diameter 8.7 µm, air hole diameter 4.6 µm, pitch 7.2 µm, and core graded refractive index profiles with height 0.0275. While Part I introduced results of differential mode delay map measurements with laser source excitation / laser-based data transmission over multimode optical fibers (MMFs) with core diameters 50 and 100 µm, combined with 6-core MOF, Part II was concerned with researches of spectral responses, measured for fiber Bragg gratings, recorded in these MOFs, and Part III was focused on laser beam profile measurements, performed for weakly and strong twisted 6-core-MOFs, Part IV reports results of MMF-MOF-MMF fiber optic structure spectral response measurements under direct tension with pull load 0…300 g.
The paper presents a method of underground dielectric optical fiber cable route tracing using a distributed acoustic sensing based on phase-sensitive optical reflectometer. The results of field tests are presented, demonstrating the performance of the method and the ability to determine the location of the cable route with an accuracy of ± 0.2 meters.
The experimental study of attenuation distribution changes of optical fiber in cable due cyclic temperature variations is represented in paper. It was observed that attenuation coefficient changes due temperature effect varies in irregular manner, that can be caused by redistribution of fiber curvature along cable. The fiber segments corresponding to the outer cable coils on the drum are most affected by temperature cycling, that can be due high thermal inertia of cable drum. The length of fiber segment with noticeable attenuation rising is approximately 500 m. The irregular local attenuation changes demonstrate the optical fiber curvature redistribution in cable due cyclic temperature variation and also can be used for estimation of variation of mechanical stresses.
The testing ground based on the different technologies of optical cable installation is described in paper. The testing ground consist from communication lines based on microduct system and using direct underground installation. The comparison of different methods for cable trace location was performed. The experimental approbation of electromagnetic induction method, ground penetrating radar method and acoustic method was carried out on the testing ground.
The paper proposes a method for localizing the location of an optical cable based on the analysis of the characteristics of a phase-sensitive reflectometer under external acoustic impact. Approbation of the methodology was carried out using a vibroacoustic monitoring system at a test site built on the territory of the university. The results of measurements of the intensity distribution of the acoustic impact along the length of the optical fiber depending on the location of the impact source are presented. The specific features of the method based on the analysis of amplitude characteristics are determined.
During installation of aerial optical fiber cables in regions with low temperatures the critical bends at the outlet from port of the closure are occures. Bending radiuses define the loads of an optical cable at installation of optical closures. In this paper influences of external factors (change of bending radius of an optical cable at the outlet from the closure port and residual deformations of a jacket) on quality of aerial optical cables installation at low temperatures are considered.
KEYWORDS: Optical fibers, Copper, Signal attenuation, Resistance, Optical communications, Telecommunications, Temperature metrology, Manufacturing, Optical fiber cables, Chemical elements
Communication cables in general and combined in particular, applied on objects of technological communication of gas, oil, processing industry and also on objects of other industries should have high reliability and resistance to mechanical loadings. This work the resistance of optical fibers and copper conductors of the combined cable to influence of the tensile and crushing loadings and also stiffness of a cable which arise at their installation is considered.
In work results of the survey conducted among professional fiber optic technicians and engineers concerned with skills in fiber optic link testing and measurement are presented. Head count was provided on the basis of the Samara Regional Telecommunication Training Centre (SRTTC) of the Povolzhskiy State University of Telecommunications and Informatics (PSUTI) during the period from February to April, 2017. The developed survey included a set of the questions allowing to estimate an work length and qualification of the engineer, his practical skills, the main activity field, typical work volume on measurements and results processing and, respectively, obligatory and optional actions for grouping, marking, structuring and hosting of the database on this or that trace of the elementary cable section of fiber optic transmission links. More than 40 employees of communication industry, business units of the big companies and also the separate enterprises of medium and small business carry on installation and maintenance of fiber optic transmission links have participated in survey. At the same time part of them have been defective, proceeding from the revealed unacceptably low skill level and/or short work length. The analysis of the received survey results have allowed to establish the corresponding subsections of course programs in the "Measurements on Fiber Optic Transmission Links" demanding, at least, enhanced studying, and in some cases – modifications and carrying out an additional lecture practical training.
This work is concerned with research of Haar wavelet threshold sensitivity for detection of non-reflective events corresponding to optical fiber fusion splices on fragments of fiber optic link traces measured by optical time domain reflectometer (OTDR). We performed test series contained 40 step-by-step repeatable splicing of the same couple of standard singlemode fibers of ITU-T Rec. G.652 spools with length 2.2 km and 4.2 km and outer termination by conventional singlemode FC/UPC pigtails for OTDR connection and following bidirectional trace measurement. Results of insertion loss estimation and accomplished by OTDR software automated detection of non-reflective event corresponding to fusion splice of described optical fibers as well as ability of its visual manual localization on trace were recorded. The first 30 splices were realized by fusion splicer conventional program for jointing standard singlemode optical fibers of ITU-T Rec. ITU-T G.652, while the next 10 splices were done under “attenuator” mode with preset increased insertion loss. Described link traces were measured by OTDR operating in a standard mode with high spatial resolution under pulse width 20 ns and appropriate dynamic range with far-end OSNR 6.5 dB at wavelength 1550 nm. As a result 80 traces were analyzed in both automated and manual modes with fusion splice insertion loss varied from 0.002 dB to 0.554 dB. At the next stage we applied continues Haar wavelet transform for detection non-reflective event on measured traces of lab fiber optic link containing described one fusion splice with total length about 6.4 km. According to results, wavelet transform of described link trace provides detection of extremely low loss non-reflective events with OTDR reading down to own error corresponding to 0.020…0.030 dB range under improved scaling over normalized spatial diagram of wavelet coefficients.
This paper presents an analysis of the data measurements of excess fiber length in the loose tubes of optical cable during the post-process quality control of ready-made products. At determining estimates of numerical characteristics of excess fiber length method of results processing of direct multiple equally accurate measurements has been used. The results of experimental research of the excess length value at the manufacturing technology of loose tube remains constant.
Research of variability excess fiber length in loose tube and in cable delivery length during manufacture of optical cable are analyzed in this paper. The excess fiber length measurements on the same optical fibers after some operations of optical cable fabrication and the analysis results of this data are introduced.
The analysis of reliability of underground fiber optic cables installed directly in ground and in a duct. Based on the calculation of the life time of the optical cable it is expected that the life time of armored optical cables installed directly in ground will be smaller than for the cable installing in duct.
Results of experimental researches of "optical microcable in a microduct" system stability to effect of freezing water are
presented. It is shown this system is steadier to water freezing in comparison to lighten optical cable in protective
polymer tube.
The paper considers possibility of using a system based on amplitude measurement method with a fiber Bragg grating as
a sensitive element. The features of measurement technique is application of Bragg gratings with a special spectrum
structure for different industries.
In article results of experimental researches of incrementation of attenuation in an optical fiber at deformation of loose
tubes are presented. The loose tubes with 4, 8, 12 fibers made from polybutyleneterephthalate were exposed to tests. It is
shown that critical value of deformation of a loose tube at which registered incrementation of attenuation exceeds
threshold value of losses (0,05 dB), changes depending on the square of the area of cross section of loose tube without
fibers practically under the linear principle. The received results of researches can be used for the forecast of optical
cable stability to influence of crushing loadings.
In article results of experimental researches of optical cable behavior in microducts at water freezing are presented. Researches were
carried out with the polymeric and steel microducts. Researches have shown that loadings which influence on a cable at water freezing
in the steel microduct is higher than in polymeric and can lead to attenuation increase in the optical fiber. In the polymeric duct
loadings more low, than in the steel. However if a polymeric microduct freeze in ice, pressure upon a cable as can cause an
incrementation of attenuation.
In article experimental results increase attenuation in dependence of deformation optical buffer tube supply. Subsequent
to the results of tests quantitative estimate increase attenuation in dependence of deformation optical buffer tube receive,
calculate of the coefficients for allowed value deformation tube estimate.
The algorithm of estimation of local lateral stress-induced birefringence in an optical fiber is represented. Results of calculation of mechanical stress and birefringence in an optical fiber under lateral stress are resulted.
In article results of experimental researches of resistance to optical cable bends on an output from closure port are submitted. The test data optical cable with increased inflexibility in extreme conditions are resulted. Recommendations on increase of resistance to small radiuses bends for of optical cables on an output from closure at the lowered temperature are considered.
Optical cable jointing is one of the most important parts of the fiber optic telecommunication line installation. For
practical applications it is interesting to use some universal material kit for the sealing of the fiber optic closure ports
with various cables, differing by their types and manufactures, in addition to basic closure kit. Here a reasonable
question occurs: is it possible to develop universal instruction manuals for various combinations of optical cable and
universal fiber optic closures, based on closure kit and generalized additional kit, contenting the most conventional
sealing materials? It is obviously, technological tests are required to answer the mentioned question. Here, some results
of investigations are represented.
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