Novel monitoring technique for passive optical networks based on optical frequency domain reflectometry and fiber bragg gratings. Osa dynamic optical frequency domain reflectometry. It can nondestructively detect fiber properties, such as length, attenuation and locations of. Inband optical frequency domain reflectometry in pons. We report a new scheme for coherent optical frequency domain reflectometry cofdr where the coherence length of the lightwaves does not limit the measureable fiber length. In a typical ofdr system a tunable laser source is swept over a certain wavelength band e. Capabilities and limitations of coherent optical frequencydomain reflectometry ofdr instrument based on the use of a tunable ber laser with a very narrow linewidth 10 khz tuned mechanically by a piezoelectric transducer makes possible. In this approach, single frequency light is converted to multi frequency light using phase modulator pm, while only two frequencies with the same light power level are adopted as the probe. Highspeed spectraldomain optical coherence tomography at 1. Incoherent optical frequency domain reflectometry for distributed thermal sensing.
Optical frequency domain reflectometry based quasidistributed high temperature sensor nan wu abstract temperature sensing in harsh environment is desired in many areas, such as coal gasification, aerospace, etc. Experimental and simple analytical investigations have been performed on modulationfrequencysweeping optical frequencydomain reflectometry hereafter. Time domain gating refers to the process of selecting a region of interest in a portion of the time domain, removing unwanted responses, and displaying the result in the frequency domain. Optical fiber sensors have attracted tremendous attention over last two decades and have been successfully employed in various sensing applications, including temperature, strain, current, and so on. Highspeed optical coherence domain reflectometry e. However, current limitation on ofdr lies in the sensing range and sensing accuracy. We present the novel concept of using data patterns as the driving signal for optical frequency domain reflectometry in.
In the new cotdr scheme, single frequency light is converted to multi frequency light and three multiplexing frequencies with the same power level are adopted as the probe, while local oscillator lo remains original single frequency. Within the framework of the european acts project bliss broadband lightwave sources and systems, a first prototype of an optical frequency domain reflectometer ofdr has been developed. Capabilities and limitations of coherent optical frequencydomain reflectometry jozef jasenek the detail theoretical analysis of the coherentoptical frequencydomain re ectometry as a method for the recovery of the backscattered signal and fresnel re ections in the sm optical ber is given. Single crystal sapphire is an excellent candidate for construction of harsh environment sensors due to its superior mechanical and. Optical time domain reflectometry otdr is an essential tool for characterizing long fibers 1. Nonlinearitycompensationfree optical frequency domain. Applications of optical frequencydomain reflectometry. Coherent optical frequency domain reflectometry cofdr is a promising technique for highresolution metrology that can find applications also in dofs distributed optical fibre sensors. Spectral and temporal phase measurement by optical frequency.
Distributed and discrete hydrogen monitoring through optical fiber sensors based on optical frequency domain reflectometry to cite this article. Pdf optical frequency domain reflectometry with a narrow. We describe a dynamic optical frequency domain reflectometry ofdr system which enables real time, long range, acoustic sensing at high sampling rate. A laser diode launches very short pulses into the fiber. Pdf we introduce a new optical frequency domain reflectometry ofdr system and processing method that utilize negative beat frequencies for the first. Botdr measurement techniques and brillouin backscatter. This paper proposes a multi frequency probe based coherent optical time domain reflectometry mfp cotdr. To enable the dbr as a standard building block in the cobra platform 1, a main challenge is the development. Frequency domain fd sensor is an instrument developed for measuring soil moisture content. Potential of optical frequency domain reflectometry fibre. Osa distributed dynamic strain measurement using optical.
Spectra for different types of backscattered power in an optical fiber. There are two frequency domain imaging methods demonstrated to date. High resolution optical frequency domain reflectometry for. We describe a technique for polarization sensitive optical frequency domain reflectometry ofdr that achieves 22 micrometer twopoint spatial resolution over 35 meters of optical length with 97 db. We present a novel method to achieve a spaceresolved long range vibration detection system based on the correlation analysis of the optical frequency domain reflectometry ofdr signals. Ofdr technology and demodulation devices are shown in figure 1. A rayleigh backscatter signal is detected for each interrogating pulse as a function of time between the launching of the pulse and the detection of the backscatter signal.
The dam safety interest group of cea technologies, inc. Optical frequency domain reflectometry ofdr has an extremely high spatial resolution and is used to locate scattered signals by measuring the frequency of rayleigh scattering generated by a modulated probe light source. Incoherent optical frequency domain reflectometry for. The samples were fabricated by smart photonics through.
The operation of an incoherent optical frequency domain reflectometer for monitoring the continuous rayleigh backscatter in a. In this work, we investigate the spectral and temporal phase measurement capabilities of ofdr. Photonics 2 014009 view the article online for updates and enhancements. Coherent optical frequency domain reflectometry using phasedecorrelated reflected and reference lightwaves abstract.
The instrument has an oscillating circuit, the sensing part of the sensor is embedded in the soil, and the operating frequency will depend on the value of soils dielectric constant. Distributed dynamic strain measurement based on optical frequency domain reflectometry is proposed. Optical correlationdomain reflectometry without optical. The backscattered light amplitude is measured from one end of a fiber as a function of optical frequency by tuning a hene laser over its linewidth.
An overview on optical frequencydomain reflectometry ofdr methods is given with ex perimental results. Incoherent optical frequencydomain reflectometry based. Understanding optical time domain reflectometry smart link mapper icon based fiber link view 1550 nm 0. Results of field measurements of the gammaradiation dose with a frequency domain optical reflectometer are presented. In this paper, we discuss the operation principles, challenges and application areas of optical frequency domain reflectometry technique. Unlike optical time domain reflectometry otdr ofdr works in the frequency domain using continuous wave cw light sources which enables higher signal to noise ratios. Optical frequencydomain reflectometery springerlink. Optical frequency domain reflectometry based on selfsweeping. May 15, 2012 a new approach to enhance the performance of coherent optical time domain reflectometry cotdr is proposed. The ofss based on the optical frequency domain reflectometry ofdr are able to achieve very high spatial resolution optical frequency domain analysis bofda 2123 and brillouin optical frequency domain re. The ability to measure doses up to 100 kgy remotely with an accuracy of up to 20% and reconstruct the absorbed dose distribution profile with a resolution of 15 cm for doses up to 9 kgy is demonstrated.
Coherent optical frequency domain reflectometry using phase. Fdr and capacitance probes measure the soil dieletric constant using two or more plates or rods which are embedded into the soil. Using optical frequency domain reflectometry techniques the main purpose of this thesis is to demonstrate the feasibility of using polarization properties of fbgs interrogated by ofdr for quasidistributed sensing applications. Optical time domain reflectometry otdr primer optical fiber optical fiber is composed of a transparent, light carrying, core surrounded by a cladding. Optical frequency domain reflectometry based on selfsweeping fiber laser.
Osa longrange vibration sensor based on correlation. The state of art performance of commercial ofdr provides 70m sensing range as. We propose and experimentally demonstrate realtime locating and speed measurement of fibre fuse by analysing the doppler shift of reflected light using optical frequencydomain reflectometry ofdr. Reflectometry otdr and incoherent optical frequency domain re. Frequency domain reflectometry how is frequency domain. The instrument has an oscillating circuit, the sensing part of the sensor is embedded in the soil, and the operating frequency will depend on the value of soils dielectric constant types of sensors.
Distributed optical fiber vibration sensor based on phasesensitive optical time domain reflectometry by meiqi ren thesis submitted to the faculty of graduate and postdoctoral studies in partial fulfillment of the requirements for the m. Optical frequency domain reflectometry based quasi. Troubleshoot wire cable assemblies with frequencydomainreflectometry s820d cable and antenna analyzer, milprf28800f certified introduction imagine being able to troubleshoot defective wire cable assemblies without having to crawl through aircraft bulkheads or remove one access panel after another searching for a cable fault. The optical frequency domain reflectometry has been developed as a highresolution measurement process for the characterisation of optical wave guides with length dimensions of just a few millimetres. Timedomain reflectometry an overview sciencedirect topics. Technique for soil electrical proper es determina on we have developed a generalized frequency domain re.
Abstract we introduce a new approach for multiplexing fiberbased ultrasound sensors using optical frequency domain reflectometry ofdr. Eickoff w and ulrich r 1981b optical frequency domain. Botdr measurement techniques and brillouin backscatter characteristics of corning singlemode optical fibers brillouin optical time domain reflectometry the brillouin optical time domain reflectometer1 botdr, sometimes referred to as the optical fiber strain analyzer, is. Swanson lincoln laboratory, massachusetts institute of technology, 244 wood street, lexington, massachusetts 021739108 d. We propose and experimentally demonstrate realtime locating and speed measurement of fibre fuse by analysing the doppler shift of reflected light using optical frequency domain reflectometry ofdr. Request pdf broadband ultrasonic sensor array via optical frequency domain reflectometry we introduce a new approach for multiplexing fiberbased ultrasound sensors using optical frequency. Coherent optical time domain reflectometry using three. Distributed sensing is obtained by probing the rayleigh backscattered light. In this paper, we demonstrate optical frequency domain imaging ofdi based on optical frequency domain reflectometry 16 using a wavelength tunable laser and standard photodetectors. Among all these distributed sensing techniques, optical frequency domain reflectometry ofdr has been given tremendous attention because of its high spatial resolution and large dynamic range. The output of the source is split into a reference arm and a sample arm which illuminates and receives the light reflected from within the sample. Also allows splice and connector losses to be evaluated as well as location of any faults on the link. Broadband ultrasonic sensor array via optical frequency.
Chen, longrange vibration sensor based on correlation analysis of optical frequencydomain reflectometry signals, opt. Gmbh, schanzenstrasse 620, 51063 cologne, germany abstract. The advantage of subdividing the laser spectral range is to improve the measurement uncertainty induced by the laser. Jan 24, 2005 high resolution optical frequency domain reflectometry for characterization of components and assemblies. One end of the sensing fiber was pigtailed to a mirror and the other end was connected, via a. Coherent heterodyne between the dual frequency probe and original single frequency local. Amplified, frequency swept lasers for frequency domain. Inband optical frequency domain reflectometry in pons frank j. Osa high resolution optical frequency domain reflectometry.
The fluctuation is detected as the frequency deviation of a beat signal from a reference interferometer, which is used as the control signal for servocontrol of the laser diode ld drive current. In the past decades, a great effort has been devoted to the mechanism and the potential applications of ofdr 2, 3. Pdf optical frequency domain reflectometry at maximum update. The key benefit of time domain reflectometry over other testing methods is the nondestructive method of these tests. Length resolution of optical frequency domain reflectometry ofdr is improved by reducing the chirping fluctuation of a laser diode. We demonstrate a novel algorithm for removing adverse effects of motion in distributed strain measurements via optical frequency domain reflectometry ofdr, using rayleigh backscatter from lowbend loss fiber as the transducer. By performing two separate measurements of the vibrated and. The operation of an incoherent optical frequencydomain reflectometer for monitoring the continuous rayleigh backscatter in a. Pdf in this paper, we discuss the operation principles, challenges and application areas of optical frequency domain reflectometry technique. The core diameter and cladding are chosen such that light will remain within the fiber. Us20150263804a1 optical frequency domain reflectometry.
Our method can detect the start of a fibre fuse within. We describe a technique for polarization sensitive optical frequency domain reflectometry ofdr that achieves 22 micrometer twopoint spatial resolution over 35 meters of optical length with 97 db sensitivity in a single measurement taking only seconds. Dynamic optical frequency domain reflectometry osa publishing. We derive and show experimentally that optical frequency domain ranging provides a significant snr gain over time domain ranging. In fdr the dielectric constant is determined by applying an oscillating charge to the circuit and measuring its resonant frequency. Large differences in the propagation constant and the spatial distribution of distinct modes degrade the performance of phasesensitive optical time domain reflectometry measurements. Distributed and discrete hydrogen monitoring through. A rayleigh backscatter signal is detected for each interrogating pulse as a function of time between the launching of the pulse and the detection of the. The distributed bragg reflector dbr is an important waveguide component for achieving wavelength selective filter functions.
Photoncounting brillouin optical timedomain reflectometry. Pdf longrange vibration sensor based on correlation. This is due to the fact that the light wave introduced into the fiber core has a fixed frequency. We demonstrate ofdrs versatility in both time and frequencydomain metrology by analyzing a fiber bragg grating fbg in both the. To enable the dbr as a standard building block in the cobra platform 1, a. Optical frequencydomain reflectometry for microbend sensor. Optical time domain reflectometry otdr is a method to detect changes in the structural strain from local reflection induced by an optical fiber sensitive to microbending. The system is based on a fast scanning laser and coherent detection scheme.
Motion compensation in distributed fiber optic sensing via. The optical frequency domain technique has been used in the analysis of discrete and distributed reflections in an optical fiber. The optical frequency domain reflectometry ofdr based on tunable narrow linewidth fiber laser is studied, including the relation between beat frequency and the distance of fiber under test fut. The system further comprises an optical detection unit 30 capable of obtaining a signal from the combined optical radiation. In the present demonstration of the method, each sensor was a short section of polyimidecoated singlemode fiber. Photoncounting brillouin optical time domain reflectometry based on upconversion detector and fiber fabryperot scanning interferometer haiyun xia,1,3 mingjia shangguan,1 guoliang shentu,2,4 chong wang,1 jiawei qiu,1 xiuxiu xia,2,4.
In this work, we develop a selfcalibration highaccuracy ofdr method to characterize the power reflection coefficient 4 of shallow etched waveguide crossings. There is presented an optical frequency domain reflectometry ofdr system 100 comprising a first coupling point 15 arranged for splitting radiation into two parts, so that radiation may be emitted into a reference path 16 and a measurement path 17. In addition, dofs based on ofdr have been used to sense many parameters. Lowcoherence, highresolution optical reflectometry for. Troubleshoot wire cable assemblies with frequencydomain. The applications of ofdr mainly include two aspects.
Incoherent optical frequencydomain reflectometry iofdr was devised soon after the inception of optical timedomain reflectometry otdr as an alternative. Capacitance, frequency domain reflectometry, soil moisture, time domain reflectometry. Mar 07, 2014 sweptwavelength interferometric techniques and, among these, optical frequency domain reflectometry ofdr are flexible and highly sensitive tools for complete characterization of amplitude and phase of target devices. The system was tested by interrogation of a 10km communication type single mode fiber and. The use of optical frequencydomain reflectometry in. By performing two separate measurements of the vibrated and nonvibrated states on a test fiber, the vibration frequency and position of a vibration event can be obtained by analyzing the crosscorrelation. Ceati, a consortium of electrical power organizations, has applied spreadspectrum time domain reflectometry to identify potential faults in concrete dam anchor cables. Dual frequency probe based coherent optical time domain. Among all types of optical fiber sensors, optical frequency domain reflectometry.
Distributed optical fiber vibration sensor based on phase. In contrast, its application for the raman backscatter measurement was introduced and patented by the company lios technology. Among all types of optical fiber sensors, optical frequency domain reflectometry ofdr has been widely studied for its. Instrumentation principles for optical time domain reflectometry. Incoherent optical frequency domain reflectometry for distributed thermal sensing karamehmedovic, emir publication date. Pdf novel monitoring technique for passive optical.
Optical frequency domain reflectometry ofdr is the basis of an emerging highdefinition distributed fiber optic sensing hdfos technique that provides an unprecedented combination of resolution and sensitivity. Optical frequency domain reflectometry for characterization. Realtime locating and speed measurement of fibre fuse. Gating can be thought of as multiplying the time domain response by a mathematical function. Optical frequency domain reflectometry is a new technique, designed to measure backreflections from optical fiber networks and components 1. Optical frequency domain reflectometry ofdr is a special technology which is used for the analysis of optical light paths and reflection characteristics in. Instrumentation principles for optical time domain. A frequency scanned optical time domain reflectometry technique includes launching a plurality of interrogating pulses into an optical fiber at a plurality of optical carrier frequencies. Coherent optical frequency domain reflectometry using phasedecorrelated reflected and reference lightwaves kohji tsuji, kaoru shimizu, tsuneo horiguchi, yahei koyamada research output. Lowcoherence, highresolution optical reflectometry for fiber length measurement by jerome thomas b. Distributed optical fiber sensors based on optical. Frequency scanned phase sensitive optical timedomain.
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