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Article-12 3-2019

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RESEARCHES OF BEND INFLUENCES ON BRILLOUIN REFLECTOGRAMS OF DIFFERENT TYPES OF OPTICAL FIBERS

Igor V. Bogachkov, Omsk State Technical University (OmSTU), Omsk, Russia, bogachkov@mail.ru

Abstract
To ensure the operation of fiber optical communication line (FOCL) for many years it is important to monitor the optical fiber (OF) integrity in the optical cable (OC). Remote fiber test systems (RFTSs) based on optical time domain reflectometers (OTDRs) are used for this purpose. But it is also necessary to detect «problem» fiber segments: segments with unauthorized access (UA), increased mechanical strain or transformed temperature. The longitudinal mechanical strain in OFs in FOCL can lead to decrease of the OC operation. Moreover, the «trouble» segments of OCs can be originated by the temperature transformations in the OFs. The crucial task in monitoring of the FOCLs is the premature diagnostics of such segments in OFs, that helps us to solve the problem before a breakdown of OC. The monitoring systems for the OFs based on the OTDR operation are not monitor the OF segments with transformed temperature and strain. For that purpose, the Brillouin optical time-domain reflectometers (BOTDR) operating at the analysis of a Mandelstam — Brillouin backscatter spectrum (MBBS) are used. FOCLs have more tamper resistance than other communication lines. In spite of the heavy expenses and development complexity, the UA to an OF can be organized, but it requires a close contact to the OF for interception, since the protective sheaths and the construction units of an OC essentially decrease the sidelight radiation.
The segments with enhanced level of sidelight radiation are applied in many UA means. These means have a high privacy because of the small changes in features of signal propagating along the OF. The sidelight optical radiation from the lateral OF area can appear in the presence of distributed and local loads on the OF, as well as on the OF bends because of the transformation of the guided modes into the leaking modes. Long-haul seamless interception can be implemented on a gentle OF bend or on exposure to the low temperatures changing a refraction index of the glass due to the increase in the level of scattering. The change of the total internal reflection due to a longitudinal strain is possible either when OF bend or the local attack on the OF are occurred. Experimental tests with the BOTDR were organized to elucidate the bend effect of various optical fibers on BOTDR-traces. The bend is a half-loop (semicircle) of the specific diameter which was gradually decreased, and MBBS in the peak area for the tested OF was observed at a minimum frequency step. As a result, the influence of a bend diameter on the level of a backscattered signal was clearly demonstrated in the trace of the MBBS. The changes in the BOTDR-traces are observed at the bend diameter in the form of a half-loop of 20-25 mm in most tested OFs. The lowest sensitivity to such bends is found in the fibers «Panda» and «ULTRA». The highest sensitivity is observed in the dispersion-shifted fiber. The changes of the traces from a standard enable a statement about a prospective UA to the FOCL to be made. The BOTDR allows us to implement the premature diagnostics of OFs in the FOCL, diagnosticate the unfeatured means of UA to the OF connected with temperature transformations, longitudinal strain and bends of the OF. The BOTDR in the monitoring system can increase its efficiency.

Keywords: optical fiber, early diagnostics, unauthorized access, monitoring, bend, strain, Brillouin reflectometer.

References

  1. Bogachkov I.V., Gorlov N.I. (2013). Methods and means of monitoring and early diagnostics of fiber-optical transmission lines. Omsk: Publishing house OmSTU. 192 p.
  2. Agraval G. Nonlinear Fiber Optics. (2011). SPb, Lan’. 592
  3. Bogachkov I.V., Trukhina A.I., Gorlov N.I. (2018). Improvement of the Monitoring Systems of Fiber Optical Communication Lines. 14th International Conference on Actual Problems of Electronic Instrument Engineering Proceedings. Novosibirsk. 1, p. 1, рр. 192-197.
  4. Lutchenko S.S., Bogachkov I.V. (2018). Influence of the optical fiber strain on the availability of fiber-optic communication lines. Systems of Signal Synchronization, Generating and Processing in Telecommunications (SINKHROINFO-2018). Minsk, рр. 1-
  5. Bogachkov I.V., Gorlov N.I. (2016). Investigation of effects of longitudinal stretching of optical fibers on Brillouin backscattering 13th International Conference on Actual Problems of Electronic Instrument Engineering Proceedings. Novosibirsk. Vol. 1, p. 1, рр. 162-168.
  6. Bogachkov I.V., Gorlov N.I. (2014). Experimental Researches of the Transverse Pressures Influences on Optical Fibers, Brillouin Backscattering Spectrum and Strain Characteristics. 12th International Conference on Actual Problems of Electronic Instrument Engineering Proceedings. Novosibirsk. 1, рр. 228-233.
  7. Bogachkov I.V., Trukhina A.I. (2017). Detection of sections with slightly changed optical characteristics in fiber optical communication lines. International Siberian Conference on Control and Communications (SIBCON–2017) Proceedings. Astana, рр. 1-
  8. Bogachkov I.V., Trukhina A.I. (2018). A Detection of Bends of the Optical Fibers by Using Brillouin Reflectometer. Systems of Signal Synchronization, Generating and Processing in Telecommunications (SINKHROINFO-2018). Minsk, рр. 1-
  9. Bogachkov I.V., Trukhina A.I., Gorlov N.I. (2018). Study of Bend Influences of Optical Fibers on Brillouin Reflectograms. 14th International Conference on Actual Problems of Electronic Instrument Engineering Proceedings. Vol. 1, p. 2, pp. 140-144.
  10. Trukhina A.I., Bogachkov I.V., Gorlov N.I. (2019). Researches the influence of bends in optical fibers of various kinds on the Brillouin traces. Systems of signals generating and processing in the field of onboard communications – Proceedings. Moscow, рр. 1-
  11. Bogachkov I.V., Inivatov D.P., Kireev A.P., Gorlov N.I. (2018). A Determination of Optical Fibers Types on the Spectrum Profile of the Mandelstam – Brillouin Scatter. 14th International Conference on Actual Problems of Electronic Instrument Engineering Proceedings. Novosibirsk. 1, p. 1, рр. 317-321.

Bogachkov I.V., Trukhina A.I., Inivatov D.P., Kireev A.P., Gorlov N.I. (2018). A classification of optical fibers types on the spectrum profile of the Mandelstam – Brillouin backscattering. Dynamics of Systems, Mechanisms and Machines (Dynamics–2018) Proceedings. Omsk, рр. 1-6.

Information about author:
Igor V. Bogachkov, Associate professor (docent) of «Communication means and information security» department of Omsk State Technical University (OmSTU), Senior Member IEEE, Omsk, Russia