Current Issue : January-March Volume : 2024 Issue Number : 1 Articles : 6 Articles
Breakage and damage of fiber optic cable fibers seriously affects the normal operation of fiber optic networks, and it is important to quickly and accurately determine the type and location of faults when they occur. Unlike the old traditional methods, the advantages of wavelet transform in singular signal detection and signal filtering are used to analyze the Optical Time Domain Reflectometer curve signal and the fault detection method of fiber communication links with no relay and a large span in a high altitude area is given, which realizes the accurate detection and location of optical fiber communication link fault events under strong noise. The proposed technology detects fiber optic faults in high-altitude environments, with an average measurement accuracy improvement of 9.8%. The maximum distance for detecting fiber optic line faults is up to 250 km, which increases the system power budget. In the simulation experiment results, the infrastructure nodes of theWuhan FiberHome Laboratory successfully verified the superiority of this technology. The method has been directly applied to the on-site detection of ultra long optical fiber links in high-altitude areas, which has good financial significance and has certain reference significance for the future real-time detection of optical fiber cables....
The distributed optical fiber sensing system uses optical fiber as the sensing element and signal transmission medium at the same time, and adopts advanced Optical Time-domain Reflectometry (OTDR) technology to detect the changes of temperature and strain at different positions along the optical fiber, thus achieving a truly distributed measurement. Using the Micro-structured Optical Time-domain Reflectometry (M-OTDR) optical fiber sensing access network technology, combined with optical link components such as fault locators, can judge the operating status of optical fiber Composite phase cable (IOPPC) lines, and detect faults (such as breakpoints) in optical fiber communication location and diagnosis. The position of the lightning strike is determined by detecting the change of polarization state caused by the transmitted light in the optical fiber inside the IOPPC before and after a lightning strike, and the positioning error is less than 1%. By observing the Brillouin frequency shift chart, the ice state can be accurately identified and the positioning function can be realized. By monitoring the vibration frequency of the IOPPC cable, the line dancing phenomenon can be detected in time to prevent line faults caused by dancing. The online safety and health monitoring of the operating state of transmission lines are realized....
An optical fiber coupler composed of two sidepolished fibers with different curvature is proposed. The live-fiber is polished with a typical radius of curvature of 0.25 m, while the branch-fiber is polished with a larger radius of curvature. Analysis shows that the proposed asymmetric structure improves the highest cross-transmission of the coupled light by up to 0.26 just by increasing the curvature of the branch-fiber (compared to the conventional symmetric arrangement) without increasing the insertion loss created by side-polishing. Experiments confirm that the proposed structure raises the highest cross-transmission by 0.15 on average when the curvature of the branch-fiber is set to 0.5 m while the curvature of the live-fiber is kept to the typical value as expected from the analysis. Our study will contribute to realizing a simple and compact machine for polishing live-fibers that offers the improved workability and portability needed for adding optical fiber couplers to live-fibers in the field....
The physics principle of pulse flight positioning is the main theoretical bottleneck that restricts the spatial resolution of the existing Raman distributed optical fiber sensing scheme. Owing to the pulse width of tens of nanoseconds, the spatial resolution of the existing Raman distributed optical fiber sensing scheme with kilometer-level sensing distance is limited to the meter level, which seriously restricts the development of the optical time-domain reflection system. In this paper, a chaos laser is proposed in the context of the physical principle of the Raman scattering effect, and a novel theory of chaos Raman distributed optical fiber sensing scheme is presented. The scheme reveals the characteristics of chaos Raman scattering light excited by a chaotic signal on the sensing fiber. Further, the chaos time-domain compression demodulation mechanism between the temperature variation information and chaos correlation peak is demonstrated. Then, the position of the temperature variation signal is precisely located using the delay time of the chaos correlation peak combined with the chaos pulse flight time. Based on this novel optical sensing mechanism, an experiment with 10 cm spatial resolution and 1.4 km sensing distance was conducted, and the spatial resolution was found to be independent of the sensing distance. Within the limit of the existing spatial resolution theory, the spatial resolution of the proposed scheme is 50 times higher than that of the traditional scheme. The scheme also provides a new research direction for optical chaos and optical fiber sensing....
Spectroelectrochemical (SEC) measurements play a crucial role in analytical chemistry, utilizing transparent or semitransparent electrodes for optical analysis of electrochemical (EC) processes. The EC readout provides information about the electrode’s state, while changes in the transmitted optical spectrum help identify the products of EC reactions. To enhance SEC measurements, this study proposes the addition of optical monitoring of the electrode. The setup involves using a polymer-clad silica multimode fiber core coated with indium tin oxide (ITO), which serves as both the electrode and an optical fiber sensor. The ITO film is specifically tailored to exhibit the lossy-mode resonance (LMR) phenomenon, allowing for simultaneous optical monitoring alongside EC readouts. The LMR response depends on the properties of the ITO and the surrounding medium’s optical properties. As a result, the setup offers three types of interrogation readouts: EC measurements, optical spectrum analysis corresponding to the volume of the analyte (similar to standard SEC), and LMR spectrum analysis reflecting the state of the sensor/electrode surface. In each interrogation path, cyclic voltammetry (CV) experiments were conducted individually with two oxidation–reduction reaction (redox) probes: potassium ferricyanide and methylene blue. Subsequently, simultaneous measurements were performed during chronoamperometry (CA) with the sensor, and the cross-correlation between the readouts was examined. Overall, this study presents a novel and enhanced SEC measurement approach that incorporates optical monitoring of the electrode. It provides a comprehensive understanding of EC processes and enables greater insights into the characteristics of the analyte....
The study is aimed at finding out the influence of bending on the waveguide from the point of view of ray equivalence with its modification based on the concept of local plane waves to provide an illustrative way to describe optical transmission in a multimode optical fiber. The paper covers the physical principles of modulation of optical transmission of fiber light guide by the bending radial variation. In addition, the authors obtained the expression for the total radiant energy in the light guide bend section/cutting in the ray equivalence. The mechanism of modulation of the fiber optical light guide and obtained mathematical expressions are the theoretical foundation for producing amplitude fiber-optic sensors....
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