外文翻譯--基于光時域分析的布里淵傳感器在入侵檢測系統(tǒng)中的發(fā)展（英文）

1、Development of fiber optic BOTDA sensor for intrusion detectionIl-Bum Kwona,*, Se-Jong Baikb, Kiegon Imb, Jae-Wang YucaDivision of Industrial Metrology, Korea Research Institute of Standard received in revised form 2 Ma

2、y 2014; accepted 21 May 2014AbstractWe present a compact fiber optic Brillouin optical time domain analysis (BOTDA) sensor system, which has the capability of detecting and locating intrusion attempts over several tens o

3、f kilometers long paths. The system employs a laser diode and two electro-optic modulators. Simulation of an intrusion effect was achieved by use of a strain-inducing setup. Distance resolution of 3 m was obtained for a

4、4.81 km long optical fiber within 1.5 s. Actual intrusion detection experiment was also performed using a step-on stage setup and clearly discernable detection signals were obtained in less than 1.5 s. # 2014 Published b

5、y Elsevier Science B.V.Keywords: Brillouin optical time domain analysis sensor; Optical fiber; Intrusion detection; Distance resolution1. IntroductionFor the purpose of protection against intruders, IR fiber sensor, magn

6、etic sensor buried under ground and leakage coaxial cable sensor are widely used [1]. IR fiber sensors are sensitive to the dust and the water molecules in the air and their detection lines must be constructed in straigh

7、t lines. Magnetic sensors and leakage coaxial cable sensors cannot be used in a harsh environment suffering electromagnetic interference. Fiber optic sensors have no such disadvantages and were developed for intrusion de

8、tection of the surround- ings, such as the outskirts of an airport and the buildings. One of the fiber optic sensors detects the loss of light associated with the cutting of optical fiber, which is inevi- table for an in

9、trusion attempt [2]. Another type of optical fiber sensor detects the change in the polarization state of light occurred when the multimode optical fiber gets bent by an intruder [3]. The multimode optical fiber sensor h

10、as a very short detection range of several meters. Fiber optic sensor utilizing speckle pattern caused by interference among propagating modes has a very high sensitivity, however, its detection range is still limited to

11、 several hundred meters [4,5]. In 1976, Barnoski and Jensen [6] reported a method to measure the loss of light nondestructively by an analysis ofRayleigh back scattering in time domain. Dakin [7] suggested that optical t

12、ime domain reflectometry (OTDR) utilizing Rayleigh back scattering can be applied to the intrusion detection. Since it measures the back-scattered light, this sensor cannot detect such intrusions that were located behind

13、 a certain intrusion whose disturbance is large enough to obscure all the later events. Sensor utilizing stimulated Brillouin scattering has overcome this problem. Stimulated Brillouin scattering fiber optic sensor emplo

14、ys a pumping pulse and a CW probe beam running along a single mode optical fiber in opposite direction and detects the stimulated Brillouin back scattering signal amplified by two light beam and acoustic wave mixing [8,9

15、]. In this method, the frequency of CW probe beam differs from the pump beam by the amount of Brillouin frequency of optical fiber to enable the ampli- fication and high intensity Brillouin scattering signal can be obtai

16、ned [10,11]. The Brillouin optical time domain analysis (BOTDA) sensor system equipped with one electro-optic modulator has been studied for measuring distributed strain and temperature, however, its signal analysis dura

17、tion is too long to use in intrusion detection [8]. In this study we developed a BOTDA sensor system, which is capable of detecting and locating intrusion attempts over several tens of kilometers long paths. Simulation o

18、f an intrusion effect was achieved by use of a strain-inducing setup installed on an optical table. We report experimental results that confirmed the distance resolution of 3 m for the fiber length of 4.81 km within 1.5

19、s detection time.Sensors and Actuators A 101 (2014) 77–84* Corresponding author. Tel.: þ82-4286-85-326; fax: þ82-4286-85-027. E-mail address: ibkwon@kriss.re.kr (I.-B. Kwon).0924-4247/02/$ – see front matter #

20、2014 Published by Elsevier Science B.V. PII: S 0 9 2 4 - 4 2 4 7 ( 0 2 ) 0 0 1 8 4 - XAssuming that the pump pulse has a narrow pulse width, W and peak power Pp(0) the power detected at Z ¼ 0 at time t ¼ 2z/v c

21、an be expressed asPdðzÞ ¼ PCWðLÞ exp ðÀaCWLÞþ gA? ? vW2? ?PCWðLÞ exp ð ÀaCWLÞPpð0Þ exp ð ÀapzÞ(3)which is valid for a suffici

22、ently low CW power PCW(L) [13]. In the above expression, g is the Brillouin gain factor, A the effective cross section of the fiber, and ap optical fiber loss coefficient at the pump pulse wavelength. The Brillouin gain

23、factor g has a well-known expression,g ¼ 2pn2p2 12gcl2rvaDnB (4)where n is the refractive index of optical fiber, p12 the photoelastic constant of the fiber, l the wavelength of the optical source, r the fiber densi

24、ty, va the acoustic velocity, DnB Brillouin gain bandwidth, and g the coefficient of polarization. Table 1 summarizes the values of parametersused in the present calculation of Brillouin gain factor and the wavelength of

25、 optical source used in the present study is 1550 nm. In the first approximation, Brillouin frequency shift increases linearly with strain,nBðeÞ ¼ nBð0Þð1 þ CeÞ (5)where e is the t

26、ensile strain and C the coefficient of strain, which is known to be 5 MHz per 0.01 for single mode optical fibers used at the 1.5 wavelength range of the optical communication.Table 1 Values of parameters used in the cal

27、culation of Brillouin gain factorParameter Symbol ValueRefractive index n 1.45 Photoelastic constant p12 0.29 Density r (kg/m3) 2.2 Â 103Acoustic velocity ua (m/s) 6 Â 103Brillouin gain bandwidth DnB (MHz) 13.4