Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/11
Browse
20 results
Search Results
Article Citation - WoS: 24Citation - Scopus: 26Fiber Bragg Grating Regeneration at 450°c for Improved High Temperature Sensing(The Optical Society, 2019) Chah, Karima; Yüksel, Kıvılcım; Kinet, Damien; Yazd, Nazila Safari; Megret, Patrice; Caucheteur, ChristopheType-I fiber Bragg gratings photo-inscribed in hydrogen-loaded B/Ge co-doped silica single-mode optical fibers have been regenerated efficiently at 450 degrees C, which is the lowest temperature reported so far. The mechanical strength of the annealed fiber is preserved while ensuring temperature sensing of the regenerated gratings up to 900 degrees C. Unlike low temperature cycles (<= 600 degrees C), an annealing process at higher temperatures revealed faster regeneration for strong gratings. Changes in grating strength were also measured before the regeneration cycle. These behaviors suggest the contribution of different mechanisms to the regeneration process with different relative dynamics. (C) 2019 Optical Society of America.Conference Object Citation - Scopus: 1Fs Fbgs as Probes To Monitor Thermal Regeneration Mechanisms(SPIE, 2019) Chah, K.; Kinet, D.; Yüksel, Kıvılcım; Caucheteur, C.This paper shows that fiber Bragg gratings written in standard single mode optical fiber with IR femtosecond pulses and point-by-point technique are high temperature resistant (< 1000 degrees C). Moreover, after calibration process, these gratings can be used as a reference to study and discriminate between different high temperature annealing mechanisms involved in other types of gratings and/or fibers. Here we have considered the regeneration process of gratings written by UV laser in boron/germanium co-doped single mode optical fiber. Hence, the monitoring of grating strength and differential wavelength shift between femtosecond and type-I gratings during annealing cycle yields the wavelength shift due to the annealing of doping (mainly boron) and UV-related defects and their relative contributions to the regeneration mechanism.Conference Object Citation - Scopus: 1A Trackside Sensor System for Train Axle Counting by Fiber Bragg Grating Accelerometer(The Optical Society, 2018) Yüksel, Kıvılcım; Kinet, Damien; Moeyaert, Veronique; Kouroussis, Georges; Caucheteur, ChristopheAn efficient method for railway traffic monitoring is presented. It uses FBG-based accelerometer together with an optimized signal processing. Sensors can be easily installed on a sleeper, without requiring interruption of the railway operability. © OSA 2018 © 2018 The Author(s)Article Citation - WoS: 62Citation - Scopus: 70Railway Monitoring System Using Optical Fiber Grating Accelerometers(IOP Publishing Ltd., 2018) Yüksel, Kıvılcım; Kinet, Damien; Moeyaert, Veronique; Kouroussis, Georges; Caucheteur, ChristopheOptimal operation, reduced energy consumption, longer service availability, and high safety level are the major concerns in today's railway transport systems. Smart monitoring systems should address these issues without interrupting railway operability. Many successful works have been carried out to provide railway monitoring functions using fiber Bragg grating (FBG) sensors on rail. Most of them are based on strain measurement due to the train passage. This paper presents a highly sensitive means for railway monitoring based on vibration measurement. FBG accelerometers placed on sleeper have been employed as sensor heads, which significantly facilitated the field sensor installation work compared to the positioning on the foot of the rail. An optimized signal demodulation algorithm has been effectively used to extract from the accelerometer traces both the axle number and the average speed information. Excellent capability of the developed system to obtain both parameters has been demonstrated by the way of field trials carried out on a Belgian railway line, during its normal operation. Easy installation, multi-function diagnosis, good data integrity, and compatibility with fiber optic sensors make the proposed sensor a good candidate for railway monitoring applications.Article Citation - WoS: 7Citation - Scopus: 9Analysis of a Novel Sensor Interrogation Technique Based on Fiber Cavity Ring-Down (crd) Loop and Otdr(Academic Press Inc., 2018) Yüksel, Kıvılcım; Yılmaz, AnılWe present the analysis of a remote sensor based on fiber Cavity Ring-Down (CRD) loop interrogated by an Optical Time Domain Reflectometer (OTDR) taking into account both practical limitations and the related signal processing. A commercial OTDR is used for both pulse generation and sensor output detection. This allows obtaining a compact and simple design for intensity-based sensor applications. This novel sensor interrogation approach is experimentally demonstrated by placing a variable attenuator inside the fiber loop that mimics a sensor head.Article Development of a Phase-Otdr Interrogator Based on Coherent Detection Scheme(Uludağ Üniversitesi, 2018) Yüksel, Kıvılcım; Jason, Johan; Wuilpart, MarcWe present in this work, the experimental demonstration of a phase-sensitive Optical Time- Domain Reflectometer (phase-OTDR) having coherent detection scheme. An analysis algorithm has also been developed to calculate amplitude and phase evolution of the experimental phase-OTDR traces. The efficiency of the analysis algorithm to determine the position of the applied vibration has been verified for a single and two simultaneous vibrations. The slow-time analysis results show a good agreement with the mathematical calculations discussed in the paper. This work could have a technological implication in many fields such as distributed vibration sensor for railway monitoring applications.Article Experimental Investigation of Refractive Index Measurement of Common Solvents and Aqueous Solutions in the Infrared Wavelengths(Balkan Yayın, 2018) İde, Cansu; Yüksel Aldoğan, Kıvılcım; Yüksel, KıvılcımWe proposed and experimentally demonstrated a fast and simple technique to measure refractive index of liquids. A commercial Optical Time-Domain Reflectometer (OTDR) was implemented for interrogating sensor tips from a remote location. The system uses Fresnel reflected light from standard single mode fiber tips as sensing points without requiring any chemical coating, delicate fiber components, and/or sophisticated architecture at the sensor head. We reported new measurements of refractive indices of common solvents and solutions at both 1550 nm and 1625 nm. The precision of the proposed measurement system was found to be in the order of 10-4. The experimental results have been validated by the way of theoretical calculations.Conference Object Rayleigh-Based Optical Reflectometry Techniques for Distributed Sensing Applications(Selçuk Üniversitesi, 2018) Yüksel, KıvılcımIn this paper, we discuss the operation principles, sensing mechanisms, challenges and application areas of the optical reflectometry techniques exploiting Rayleigh scattering phenomenon, considering both time- and frequency-domain schemes. Among various distributed optical fiber sensor (DOFS) systems interrogated by optical reflectometry techniques, a special emphasis was given, in this paper to distributed acoustic sensor (DAS) interrogation methods. Recent progresses obtained through our research collaborations are also presented.Conference Object Laboratory Evaluation of a Phase-Otdr Setup for Railway Monitoring Applications(Institute of Electrical and Electronics Engineers Inc., 2017) Jason, J.; Yüksel, Kıvılcım; Wuilpart, MarcPhase-sensitive optical time-domain reflectometry (phase-OTDR) has recently drawn increased attention for applications within the railway transportation sector. In this paper we present a laboratory approach to demonstrate the feasibility of an interrogator of vibrations along railways by means of fiber-optic cables. Contrary to the common use of piezo-electric phase modulators in laboratory setups, a vibration shaker is used to excite a plastic tube to which the fiber is attached. Measurement of event position and frequency is demonstrated in a range up to 7000 Hz.Conference Object Citation - WoS: 2Citation - Scopus: 2Fiber Optik Sensörler ile Sıvılarda Kırılma İndisi Ölçüm Yöntemlerinin Analizi(Institute of Electrical and Electronics Engineers Inc., 2017) İde, Cansu; Yüksel, KıvılcımRefractive index (RI) is one of the physical properties of material, such as boiling/melting point, density, and elasticity. As one of the distinctive features of the material, measurement of the RI is nowadays used in many areas including the food, oil and petroleum industry, biomedical applications, and environmental analysis. In recent years, fiber optic based refractometers become highly popular thanks to the advantages they provide compared to other methods used in the above mentioned fields. Two fiber optic refractive index sensors were investigated in this study: Fresnel reflection based-and long-period fiber grating (LPFG) based-refractometers. The former uses SMF fiber tip as sensing point interrogated by an OTDR from a distant location, where the latter examines the changes in the resonance wavelength. Experimental work realised on different concentrations of glucose-water and glycerol-water solutions successfully demonstrated the capability of the proposed sensor in measuring RI of liquid chemicals with a precision of 1.7×10-4 (Fresnel-based sensor) and maximum sensitivity of 193.42 nm/RIU (LPGF based sensor).