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1

Accurate Location of Fiber Cable Fault with OTDR

Borzycki Krzysztof, Gajewski Paweł

Journal of Telecommunications and Information Technology

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2021

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nr 4

42--52

EN

The paper reviews the factors limiting the accuracy of locating a fiber optic cable fault when using an optical time domain reflectometer (OTDR) and describes an error estimation method for typical use cases. The primary source of errors lies in the complex relationship between the length of the optical fiber (measured by OTDR), its routing, cable design depending on cable design and type of installation (i.e. duct, directly buried, aerial) as well as the spare lengths used for service purposes. The techniques which considerably improve the accuracy of the fault localization processes are presented, the importance of accurate documentation of the network and of referencing the fault location to the nearest splice instead of end of the line are discussed, as is the absence of cable helix factor in data sheets.

2

Wpływ temperatury na wartość współczynnika załamania w rdzeniu światłowodu jednomodowego

Torbus S. A.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 3

158--163

PL

W artykule omówiono budowę włókna światłowodowego, zdefiniowano profil współczynnika załamania w rdzeniu światłowodu oraz określono wpływ temperatury na wartość współczynnika załamania szkła optycznego. Korzystając z opracowanego w środowisku MathCAD modelu matematycznego światłowodu telekomunikacyjnego, określono wpływ temperatury na wartość współczynnika w jego rdzeniu, w zależności od długości fali świetlnej, stężenia molowego domieszki GeO2 oraz różnicy termicznej zmiany polaryzowalności i termicznej rozszerzalności objętościowej. Sformułowano wnioski dotyczące wpływu rozpatrywanych czynników na czułość temperaturową szkła optycznego o strukturze SiO2–GeO2 oraz przydatności tychże szkieł do realizacji polarymetrycznych czujników natężenia prądu wykorzystujących magnetooptyczne zjawisko Faradaya oraz rozłożonych czujników temperatury wykorzystujących wymuszone rozproszenie Rayleigha.

EN

The article discussed the construction of optical fiber, the definition of refractive index profile in the fiber’s coreand the influence of temperature on the refractive index of optical glass. Using the mathematical model of the single mode fiber, which was realized in an MathCAD application, the effect of temperature on the value of refractive index in their core, depending on the wavelength of the light, the molar concentration of GeO2 dopant and the difference between the thermal changes of polarizability and the thermal volumetric expansion were has been determined. Conclusions regarding the impact of the factors considered on the temperature sensitivity of optical glass structure SiO2–GeO2 and of the use of these glasses for the implementation of polarimetric current sensors used Faraday effect and distributed temperature sensors using simulated Rayleigh scattering have been formulated.

3

Signal-to-noise analysis in a counter-pumped fiber Raman amplifier

Felinskyi G, Dyriv M

Optica Applicata

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2014

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Vol. 44, nr 4

493--501

EN

The light gain efficiency due to Raman scattering in a distributed fiber Raman amplifier is a subject of our investigation. The detailed analysis of noise properties at one-wave optical signal amplification in a single-mode fiber in the scheme of counter-pumped fiber Raman amplifier is realized in the paper. Experimental results of the amplified spontaneous emission with backward pumping as a base of optical noise evaluation are presented. Raman gain spectrum for a coherent Stokes low-powered signal is calculated and it is compared with the observed spectrum of non-coherent amplified spontaneous emission noise. It is shown that an output optical signal has higher gain than the amplified spontaneous emission and it results in the appreciable growth in the output optical signal-to-noise ratio.

4

Section of gradient index multimode fiber as an elementary fiber grin lens

Sankowska A., Skornowicz J.

Optica Applicata

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2011

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Vol. 41, nr 2

367--373

EN

In the work presented below it has been demonstrated that the section of the multimode fiber with gradient refractive index distribution in the core spliced to a singlemode fiber modifies the path of rays in a manner analogous to the GRIN type lens. Using a small section of graded-index optical fiber as a lens provides several advantages, including: small size, well matched fiber-lens diameter, stable fiber-lens interface, and a comparatively low cost of fabrication of an elementary fiber lens. The aim of the present paper is to discuss the technological process that enables fabrication of elementary fiber lenses with different lengths, and the measurement system for analysis of optical power density distribution in the light beam modified by an elementary fiber lens.

5

Simplified coupling power model for fibers fusion

Saktioto J., Ali J., Fadhali M.

Opto-Electronics Review

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2009

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Vol. 17, No. 3

193-199

EN

Fiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800-1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.