Principles of Automated Data Processing  of Mandelstam – Brillouin Backscatter Characteristics for Evaluating the State  of Optical Fibers

For early diagnostics of the state of optical fibers (OFs) located in the laid optical cables (OCs), it is necessary to identify potentially unreliable sections of the S in advance, which over time can lead to the destruction of fibers and disrupt the normal operation of fiber-optic communication lines (FOCLs). For diagnosis and forecasting of the state of the OFs that are in the laid OCs, Brillouin optical pulse reflectometers (BOTDR) are used, in which the back-reflected signal of the spontaneous Mandelstam – Brillouin scattering (MBS) is analyzed. In the process of obtaining a trace of the distribution of the Mandelshtam – Brillouin backscatter spectrum (MBBS) along the OF, the Brillouin frequency shift (BFS) is determined. After this, a graphs of the distribution of strain along the light-guide is constructed. A classification of varieties of single-mode optical fibers based on analysis of the MBS characteristics is discussed in this paper. It is shown how by the characteristics of the frequency profiles of the MBBS, one can determine the type of fiber and also evaluate the change in the strain and BFS. The MBBS profile come under influence by the functional dependence of the distribution of acoustic modes in the OF, their longitudinal direction. Both of them depend on the structure of the OF layers, as well as on the types and concentration of various alloying additives of the core OF. For single-mode OFs, when describing the MBS process, it is necessary to take into account the spatial distribution and interaction of the main optical and several acoustic modes. After uploading the data file from the BOTDR, it is necessary to process the information in order to determine the BFS and the strain along the light-guide. This process can be automatized, if a database has been formed. When a new Brillouin reflectogram appears, the MBBS profile from it must be compared with templates from the generated database. To classify the fiber types, it is necessary to evaluate the degree of matching of the explored MBBS profile with all the database templates. To assess the degree of coincidence of the considered MBBS profiles, needs to be defined the overall part of the frequency band for analysis. The programs for the automated processing of the Brillouin reflectograms data are presented. Based on the analysis of Brillouin reflectograms, it is possible to identify a factor that had a predominant influence on the characteristics of the MBS signal in the explored sections of single-mode optical fibers. As a result of the program's work, a template is output that, according to the program's estimates according to the algorithm described above, has the best match with the downloaded image. To increase the accuracy of assessing the similarity of the explored profiles, it is also recommended to carry out calculations according to the above-described algorithm when aligning not only the maximum levels, but also combine the graphs along the frequency axis. It is clear that during the overlay the frequencies of the "peaks" (BFS), there will be a very strong coincidence of the patterns, and the type of the OFs will be determined correctly, while at some temperatures a good degree of similarity with another pattern could be obtained. The obtained estimate of the BFS allows one to determine the degree of the OF strain. The identification of the MBBS profile and other characteristics of the MBS allows you to create a database various types of the OFs and different manufacturers, which can be used to classify the type of the OFs. The results presented in this exploratory development show how based on the analysis of BOTDR reflectograms, it is possible to automatically determine the type of the OF in OC, to identify a factor that has a predominant effect on the frequency response and strain in the explored sections of the OFs in FOCL, which can improve the efficiency of predicting the operational parameters of the physical channels of optical telecommunication systems.

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Normal acoustic modes and Brillouin scattering in single-mode optical fibers

Physical Review B ◽

10.1103/physrevb.19.4986 ◽

1979 ◽

Vol 19 (10) ◽

pp. 4986-4998 ◽

Cited By ~ 69

Author(s):

P. J. Thomas ◽

N. L. Rowell ◽

H. M. van Driel ◽

G. I. Stegeman

Keyword(s):

Optical Fibers ◽

Brillouin Scattering ◽

Single Mode ◽

Acoustic Modes

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Extreme Radiation Sensitivity of Ultra-Low Loss Pure-Silica-Core Optical Fibers at Low Dose Levels and Infrared Wavelengths

Sensors ◽

10.3390/s20247254 ◽

2020 ◽

Vol 20 (24) ◽

pp. 7254

Author(s):

Adriana Morana ◽

Cosimo Campanella ◽

Jeoffray Vidalot ◽

Vincenzo De Michele ◽

Emmanuel Marin ◽

...

Keyword(s):

Optical Fibers ◽

Data Transfer ◽

Radiation Detector ◽

Single Mode ◽

Fiber Types ◽

X Rays ◽

Low Loss ◽

Distributed Sensors ◽

Pure Silica ◽

Silica Core

We report here the response of a commercial ultra-low loss (ULL) single-mode (SM) pure silica core (PSC) fiber, the Vascade EX1000 fiber from Corning, associated with 0.16 dB/km losses at 1.55 µm to 40 keV X-rays at room temperature. Today, among all fiber types, the PSC or F-doped ones have been demonstrated to be the most tolerant to the radiation induced attenuation (RIA) phenomenon and are usually used to design radiation-hardened data links or fiber-based point or distributed sensors. The here investigated ULL-PSC showed, instead, surprisingly high RIA levels of ~3000 dB/km at 1310 nm and ~2000 dB/km at 1550 nm at a limited dose of 2 kGy(SiO2), exceeding the RIA measured in the P-doped SM fibers used for dosimetry for doses of ~500 Gy. Moreover, its RIA increased as a function of the dose with a saturation tendency at larger doses and quickly recovered after irradiation. Our study on the silica structure suggests that the very specific manufacturing process of the ULL-PSC fibers applied to reduce their intrinsic attenuation makes them highly vulnerable to radiations even at low doses. From the application point of view, this fiber cannot be used for data transfer or sensing in harsh environments, except as a very efficient radiation detector or beam monitor.

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Method for Estimation of Reflection on Fiber Optic Connection Based on Analysis of Images of End Surfaces of Ferrule Connectors

Proceedings of Telecommunication Universities ◽

10.31854/1813-324x-2020-6-4-16-27 ◽

2020 ◽

Vol 6 (4) ◽

pp. 16-27

Author(s):

A. Bourdine ◽

S. Pashin

Keyword(s):

Reflection Coefficient ◽

Optical Fibers ◽

Experimental Verification ◽

Fiber Optic ◽

Single Mode ◽

The State ◽

Practical Applications ◽

Standard Field ◽

Alternative Method

This work presents an alternative method for evaluating the reflection coefficient at a detachable connection of single-mode optical fibers based on the results of the analysis of images of the contaminated end surface of the ferrule of a pair of connectors of the studied joint, obtained with a standard field set of video diagnostics of the state of fiber-optic connectors. The results of experimental verification of the proposed method are presented, which have demonstrated the potential of its use in practical applications of "contactless" determination of the reflection coefficient on a fiber-optic connector.

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Phase Sensitivity of Conventional Single-Mode, PANDA, and Holey Optical Fibers: A Comparison Study

10.21236/ada408460 ◽

2002 ◽

Author(s):

Wilson K. Chiu ◽

Jason M. Maguire ◽

Marilyn J. Berliner

Keyword(s):

Optical Fibers ◽

Single Mode ◽

Phase Sensitivity ◽

Comparison Study

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Design Considerations in Reduced-Diameter Single-Mode Optical Fibers

10.21236/ada633188 ◽

2002 ◽

Author(s):

Wilson K. Chiu ◽

Gregory H. Ames ◽

Marilyn J. Berliner

Keyword(s):

Optical Fibers ◽

Single Mode ◽

Design Considerations

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Sensing, Actuation, and Control of the SmartX Prototype Morphing Wing in the Wind Tunnel

Actuators ◽

10.3390/act10060107 ◽

2021 ◽

Vol 10 (6) ◽

pp. 107

Author(s):

Nakash Nazeer ◽

Xuerui Wang ◽

Roger M. Groves

Keyword(s):

Wind Tunnel ◽

Optical Fibers ◽

Fiber Optic ◽

Experimental Testing ◽

Single Mode ◽

Fiber Optic Sensor ◽

Sensor Data ◽

Random Errors ◽

Morphing Wing ◽

Actuator Dynamics

This paper presents a study on trailing edge deflection estimation for the SmartX camber morphing wing demonstrator. This demonstrator integrates the technologies of smart sensing, smart actuation and smart controls using a six module distributed morphing concept. The morphing sequence is brought about by two actuators present at both ends of each of the morphing modules. The deflection estimation is carried out by interrogating optical fibers that are bonded on to the wing’s inner surface. A novel application is demonstrated using this method that utilizes the least amount of sensors for load monitoring purposes. The fiber optic sensor data is used to measure the deflections of the modules in the wind tunnel using a multi-modal fiber optic sensing approach and is compared to the deflections estimated by the actuators. Each module is probed by single-mode optical fibers that contain just four grating sensors and consider both bending and torsional deformations. The fiber optic method in this work combines the principles of hybrid interferometry and FBG spectral sensing. The analysis involves an initial calibration procedure outside the wind tunnel followed by experimental testing in the wind tunnel. This method is shown to experimentally achieve an accuracy of 2.8 mm deflection with an error of 9%. The error sources, including actuator dynamics, random errors, and nonlinear mechanical backlash, are identified and discussed.

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Design and analysis of a fiber-optic sensing system for shape reconstruction of a minimally invasive surgical needle

Scientific Reports ◽

10.1038/s41598-021-88117-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Aizhan Issatayeva ◽

Aida Amantayeva ◽

Wilfried Blanc ◽

Daniele Tosi ◽

Carlo Molardi

Keyword(s):

Performance Analysis ◽

Minimally Invasive ◽

Optical Fibers ◽

Single Mode ◽

Spectral Shift ◽

Shape Reconstruction ◽

Minimally Invasive Surgical ◽

Working Principle ◽

Doped Fibers ◽

Distributed Measurement

AbstractThis paper presents the performance analysis of the system for real-time reconstruction of the shape of the rigid medical needle used for minimally invasive surgeries. The system is based on four optical fibers glued along the needle at 90 degrees from each other to measure distributed strain along the needle from four different sides. The distributed measurement is achieved by the interrogator which detects the light scattered from each section of the fiber connected to it and calculates the strain exposed to the fiber from the spectral shift of that backscattered light. This working principle has a limitation of discriminating only a single fiber because of the overlap of backscattering light from several fibers. In order to use four sensing fibers, the Scattering-Level Multiplexing (SLMux) methodology is applied. SLMux is based on fibers with different scattering levels: standard single-mode fibers (SMF) and MgO-nanoparticles doped fibers with a 35–40 dB higher scattering power. Doped fibers are used as sensing fibers and SMFs are used to spatially separate one sensing fiber from another by selecting appropriate lengths of SMFs. The system with four fibers allows obtaining two pairs of opposite fibers used to reconstruct the needle shape along two perpendicular axes. The performance analysis is conducted by moving the needle tip from 0 to 1 cm by 0.1 cm to four main directions (corresponding to the locations of fibers) and to four intermediate directions (between neighboring fibers). The system accuracy for small bending (0.1–0.5 cm) is 90$$\%$$ % and for large bending (0.6–1 cm) is approximately 92$$\%$$ % .

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Dispersion properties of single-mode optical fibers in telecommunication region: poly (methyl methacrylate) (PMMA) versus silica

Journal of Optical Communications ◽

10.1515/joc-2020-0172 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Hassan Pakarzadeh ◽

Seyed Mostafa Rezaei ◽

Mostafa Taghizadeh ◽

Forough Bozorgzadeh

Keyword(s):

Methyl Methacrylate ◽

Optical Fibers ◽

Spectral Range ◽

Structural Parameters ◽

Practical Importance ◽

Single Mode ◽

Dispersion Characteristics ◽

Poly Methyl Methacrylate ◽

Dispersion Wavelength ◽

Zero Dispersion Wavelength

AbstractIn this paper, the dispersion characteristics of two standard single-mode optical fibers (SMFs), fabricated with silica and poly (methyl methacrylate) (PMMA) are studied in telecommunication spectral regions. The effect of structural parameters, such as the radius of the fiber core and the relative core-cladding index difference, is numerically investigated. It is found that over whole spectral range, the PMMA-based SMF shows lower dispersion than the silica SMF. Also, the zero-dispersion wavelength (ZDW) of PMMA-based SMF is longer than that of silica fiber. The results may be of practical importance for the telecommunication applications.

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