CN100582658C - Bending radius measuring apparatus based on optical fibre laser - Google Patents

Bending radius measuring apparatus based on optical fibre laser Download PDF

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CN100582658C
CN100582658C CN 200810052349 CN200810052349A CN100582658C CN 100582658 C CN100582658 C CN 100582658C CN 200810052349 CN200810052349 CN 200810052349 CN 200810052349 A CN200810052349 A CN 200810052349A CN 100582658 C CN100582658 C CN 100582658C
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fiber
laser
optical fiber
optical
division multiplexer
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CN 200810052349
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CN101236075A (en )
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兰玉文
关柏鸥
波 刘
周海滨
开桂云
罗建花
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南开大学
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Abstract

The invention discloses a bending radius measuring instrument based on an optical fiber laser, which comprises a single mode fiber, an optical fiber wavelength division multiplexer, further an optical fiber laser, an optical pumping source, an isolator, a photo-detector and a spectrum analyzing arrangement, wherein the optical fiber laser is connected with the optical fiber wavelength division multiplexer via the single mode fiber, the optical fiber wavelength division multiplexer is connected with the optical pumping source and the isolator separately via the single mode fiber, the isolator is in parallel connection with the photo-detector and the spectrum analyzing arrangement sequentially. The optical fiber laser employs a liner cavity structure of DBR, which comprises sensing fibers formed by fiber gain and a fiber grating pair with matching wavelengths, wherein the sensing fibers are connected between a fiber grating pair with matching wavelengths. The invention employs the optical fiber as a sensing element, and the bending sensing element has the advantages of compact conformation, high measurement accuracy, anti-interference and corrosion prevention, adapting for working in hostile environment. In measurement mode, the bending radius measuring instrument employs a cross-polarized single longitudinal mode DBR optical fiber laser as the sensing element.

Description

弯曲半径测量仪 Bending radius meter

技术领域 FIELD

本发明涉及一种弯曲半径测量仪。 The present invention relates to a bending radius meter. 特别是涉及一种利用正交偏振的单纵模光纤激光器中增益光纤对弯曲敏感的特性,将其中的增益光纤作为传感基质,可以测量增益光纤的弯曲半径的基于光纤激光器的弯曲半径测量仪。 Particularly relates to a single longitudinal mode orthogonally polarized fiber laser gain characteristics of an optical fiber sensitive to bending, in which the gain fiber as a sensing matrix may be measured based on the bending radius of the fiber laser measuring instrument gain fiber bend radius .

背景技术 Background technique

DBR光纤激光器由两个波长匹配的光纤Bragg光栅做腔镜,单模掺铒光纤作为增益介质构成线性谐振腔。 DBR fiber laser cavity mirror made of two fiber Bragg grating wavelengths matched, single-mode erbium doped fiber as the gain medium constituting the linear cavity. DBR光纤激光器要求D服光纤激光器工作在单纵模状态,就必须要求腔长足够短,从而在激光器的自由光谱范围内只有一个纵模存在。 D claim DBR fiber laser fiber laser working clothes in a single longitudinal mode condition must be sufficiently short cavity length required, so that the presence of only one longitudinal mode within the free spectral range of the laser. 由于任何一个纵模都有正交偏振的两个简并的偏振态, 一旦腔内引起双折射的变化,两个偏振态不再简并, 产生拍频。 Since any one longitudinal mode has two orthogonal degenerate polarized polarization state and, once the change in birefringence caused by the cavity, the two polarization states is no longer degenerate, the beat frequency is generated. 此拍频信号可以直接由光电探测器转化为电信号并由频谱分析设备测量得到。 This beat signal can be directly converted into an electrical signal by the photodetector device measured by spectral analysis. 根据此DBR激光器的原理特性,其拍频除与光纤光栅的波长有关之外,还与增益光纤的双折射有关。 The principle features of this DBR laser, which is related to the beat wavelength other than the fiber grating, birefringent gain fiber is also relevant. 如增益光纤为单模光纤时,它的双折射主要是由两种原因引起,光纤芯截面几何尺寸的偏差与光弹效应产生的机械应力。 When the gain fiber such as a single mode fiber, which is mainly caused by the birefringence of two reasons, the mechanical stress of the optical fiber core sectional geometry deviation photoelastic effect generated. 光纤材料石英有很高的杨氏模量, 这决定了光纤制成后几乎不可能再有形状的变化。 Material such as quartz fiber have a high Young's modulus, which is almost impossible to have a decided change in shape after the fiber is made. 但外来应力可以通过光弹效应引起光纤的感应双折射。 However, stress can cause extraneous induced birefringence fiber by photoelastic effect. 当增益光纤弯曲时,其双折射率也将发生变化,进而引起其出射激光的拍频发生变化。 When the gain fiber is bent, birefringence will change, thereby causing an emitted laser beam changes the beat frequency occurs. 因此,通过检测拍频变化,可以推知增益光纤的弯曲半径。 Thus, by detecting changes in the beat frequency, the gain can be inferred bend radius of the fiber.

发明内容 SUMMARY

本发明所要解决的技术问题是,提供一种利用光纤作为传感器件,利用DBR激光器的拍频效应,将传感光纤所在部位的弯曲半径的变化转换为激光器拍频的变化,通过检测这种拍频变化来达到测量弯曲半径的目的基于DBR激光器的弯曲半径测量仪。 The present invention solves the technical problem is to provide an optical fiber as a sensor utilizing shoot member, using the DBR laser frequency effect, convert the change bend radius sensor portion where the optical fiber laser of the beat frequency changes, by detecting this Sign frequency variation to achieve the purpose of measuring the bending radius of the bending radius of the DBR laser-based measuring device.

本发明所采用的技术方案是: 一种基于光纤激光器的弯曲半径测量仪,包括有:单模光纤,光波分复用器,还设置有光纤激光器,光纤泵浦源,隔离器,光电探测器,频谱分析装置,其中,所述的光纤激光器通过单模光纤与光波分复用器连接,光波分复用器分别通过单模光纤与光纤泵浦源以及隔离器相连,隔离器与光电探测器、频谱分析装置依次串联连接。 The technical proposal of the present invention is: based on the bending radius of the fiber laser measuring instrument, comprising: a single mode optical fiber, wavelength division multiplexer, provided with a fiber laser pumping source, an isolator, a photodetector , spectral analysis means, wherein the single mode fiber laser by a wavelength division multiplexer connected to the optical fiber, wavelength division multiplexer connected respectively with the optical fiber single-mode fiber pumping source, and an isolator, the isolator and the photodetector , spectral analysis means sequentially connected in series.

所述的光纤激光器采用DBR的线性腔结构。 The linear cavity of the fiber laser of the DBR structure.

所述的光纤激光器为DBR光纤激光器,包括有传感光纤和波长匹配的光纤光栅对, 其中,传感光纤连接在一对波长匹配的光纤光栅对之间。 The DBR fiber laser is a fiber laser comprising an optical fiber and the sensing fiber grating wavelength matching pair, wherein the sensing fiber is connected between a pair of fiber grating wavelength matching pair.

所述的传感光纤采用能由弯曲引起光纤双折射以至光纤激光器产生拍频变化的增益光纤构成。 Using the sensing fiber birefringence can be caused by bending of the fiber as well as fiber laser generates beat frequency varying gain fiber configuration.

3所述的泵浦源采用光纤泵浦激光器。 3, the pump source is fiber pump laser.

还可以采用具有反射特性的光学器件取代波长匹配的光纤光栅对构成光纤激光器。 It may also be employed in an optical device having a reflection characteristic wavelength matching substituted constituting FBG fiber lasers. 本发明的基于光纤激光器的弯曲半径测量仪,采用光纤作为传感器件,基于光纤本身的优点,这种弯曲传感器件具有结构紧凑、测量精度高、抗干扰,耐腐蚀,适合在恶劣环境下工作等特点。 Bend radius of fiber-based laser measuring device of the present invention, a fiber optics device, based on the advantages of the fiber itself, such a bending sensor having compact structure, high precision, interference, corrosion resistance, suitable for working in harsh environments, etc. features. 同时,测量方式上不同于光纤中传统的波长检测的方式,而是利用正交偏振的单纵模DBR光纤激光器为传感元件。 Meanwhile, in a manner different from the conventional optical wavelength detection on the measurement, but the use of orthogonal polarizations DBR single longitudinal mode fiber laser as the sensing element. 采用频谱仪进行拍频解调。 The analyzer uses the beat frequency demodulation. 因而具有性价比高等优点。 Which has cost advantages.

附图说明 BRIEF DESCRIPTION

图1是本发明的整体结构示意图其中: FIG 1 is a schematic overall configuration of the present invention wherein:

1:传感光纤3:单模光纤 1: sensor fiber 3: single-mode fiber

5:光纤泵浦源7:光电探测器9:光纤激光器 5: fiber pump source 7: photodetector 9: fiber laser

具体实施方式 detailed description

下面结合实施例和附图对本发明的基于光纤激光器的弯曲半径测量仪做出详细说明。 DRAWINGS made to the bending radius of the fiber laser-based measuring device according to the present invention, the detailed description and embodiments.

本发明利用光纤作为传感器件,并利用DBR激光器的拍频进行测量分析。 The present invention utilizes an optical fiber as a sensor element, and using the DBR laser beat frequency measurement and analysis. 采用改变激光器谐振腔的双折射的方式改变激光器的拍频,通过检测拍频的变化测量双折射的变 A birefringent change the way the laser cavity to change the laser beat frequency, the beat detected by measuring the change of birefringence becomes

化,从而测量弯曲半径。 , Thereby measuring the bending radius. 其特点是:弯曲导致传感光纤产生感生双折射,从而导致激光 Its characteristics are: generation due to bending induced birefringence of the sensing fiber, thereby causing the laser

器拍频的变化,通过频谱仪测量激光器拍频的变化来感测弯曲半径的大小。 Beat frequency variation is measured by the change in the laser beat frequency spectrum analyzer to sense the size of the sensing radius of curvature.

如图1所示,本发明的光纤激光器的弯曲半径测量仪,包括有:光纤激光器9,单模光纤3,光波分复用器4,光纤泵浦源5,隔离器6,光电探测器7,频谱分析装置8,其中,所述的光纤激光器9通过单模光纤3与光波分复用器4连接,光波分复用器4分别通过单模光纤3与光纤泵浦源5以及隔离器6相连,隔离器6与光电探测器7、频谱分析装置8依次串联连接。 As shown, the optical fiber laser of the present invention, a radius of curvature measuring device, comprising: a fiber laser 9, single-mode fiber 3, an optical wavelength division multiplexer 4, the pump source fiber 5, spacer 6, photodetector 7 , spectral analysis means 8, wherein said fiber laser 9 is connected through a single mode optical fiber 3 and the optical wavelength division multiplexer 4, the optical wavelength division multiplexer 4 and 3 respectively, through a single mode fiber optical pump source 5 and a separator 6 connected to the separator 6 and photodetector 7, spectral analysis means 8 are sequentially connected in series. 所述的光纤激光器9采用D服的线性腔结构。 Said linear fiber laser cavity structure 9 D clothing. 所述的泵浦源5采用光纤泵浦激光器。 5 using the pump source fiber pump laser.

上述的光纤激光器9为DBR光纤激光器,包括有传感光纤1和波长匹配的光纤光栅对2,其中,传感光纤l连接在一对波长匹配的光纤光栅对2之间。 9 of the above-described fiber laser DBR fiber laser, comprising a sensing fiber and fiber grating wavelength matching to 2, wherein the sensing fiber connector l of a wavelength matching between two FBG. 其中,所述的传感光纤1采用能由弯曲引起光纤双折射以至光纤激光器产生拍频变化的增益光纤构成。 Wherein said sensing fiber 1 caused by bending can be employed as well as fiber birefringence fiber laser generates beat frequency varying gain fiber configuration.

根据增益光纤1的吸收波长,可以选用相应的泵浦源5的工作波长。 The absorption wavelength of a gain fiber, can choose the operating wavelength of the respective pump source 5. 如增益光纤1 选用单模掺铒光纤时,泵浦源5的工作波段为980nm或1480nm。 When the gain fiber such as a single mode erbium-doped fiber chosen, the pump source operating wavelength band of 980nm or 5 1480nm. 匹配光纤光栅对2的中 Matched pair FBG 2

2.波长匹配的光纤光栅对 2. The fiber grating wavelength matching of

4:光波分复用器 4: WDM

6:隔离器 6: Isolator

8:频谱分析装置心波长为1542. OOOnrn。 8: is a central wavelength of spectral analysis means 1542. OOOnrn. 传感用增益光纤1采用15,的掺铒光纤。 1 employed for sensing gain fiber 15, erbium-doped fiber. 光电探测阵列7采用10G的APD光电探测器。 7 photo detector array using an APD photodetector 10G. 单模光纤3采用1550nm波段的单模光纤。 3 A single-mode fiber band 1550nm single mode fiber.

本发明中还可以采用具有反射特性的光学器件取代波长匹配的光纤光栅对2构成光纤激光器9,如采用光学反射镜片、光纤环镜等作为反射腔镜构成光纤激光器。 The present invention may also be employed in an optical device having a reflection wavelength matching characteristics substituted 2 constituting the fiber grating fiber laser 9, as reflected by optical lenses, fiber loop mirror as a reflecting mirror constituting an optical fiber laser.

本发明的测试原理是: Test principle of the present invention are:

对于正交偏振的单纵模DBR光纤激光器,设增益光纤外半径为r,当光纤弯曲成半径 For single longitudinal mode fiber laser DBR orthogonal polarization, gain fibers disposed outside radius r, when the optical fiber is bent to a radius

R(R》r)时:感生双折射邻=&—艮可以表示为: When R (R "r): o = & induced birefringence - Burgundy can be expressed as:

G、2 G, 2

Bb-邻-0.25n3(l + "(Pu-Pi2) Bb- o -0.25n3 (l + "(Pu-Pi2)

、R乂 , R qe

(1) (1)

式中"是Si02的泊松(Poisson)比,Si02的"《0.16, p11=0. 12, P12=0. 27, n=l. 46。 Wherein "is Poisson Si02 (the Poisson) ratio, the Si02" "0.16, p11 = 0. 12, P12 = 0. 27, n = l. 46. 因此得到- So get -

Bb = —0.093n Bb = -0.093n

R R

由于光纤有固有双折射B。 Since the optical fiber has intrinsic birefringence B. ,设弯曲产生的感应双折射与固有双折射之间的轴向夹角为0,则矢量叠加得到总的双折射度为: , Provided axially between the bending angle of the induced birefringence and intrinsic birefringence is 0, the vector superposition to give a total degree of birefringence:

B = 、/B02 + Bb2 + 2B0Bb cos ^ B =, / B02 + Bb2 + 2B0Bb cos ^

由于腔内双折射,激光器谐振腔内产生两个正交偏振的不同模式的光束,两个模式之间的频差为- Since the cavity birefringence, the laser resonant cavity produces a beam of two different orthogonal polarization modes, the frequency difference between the two modes -

A i/ = ^ = X 、/B02 + Bb2 + 2BnBh cos ^ A i / = ^ = X, / B02 + Bb2 + 2BnBh cos ^

=h = H

n2Bn2 + n2Bn2 +

-0.093 -0.093

、2 j乂 , 2 j qe

"12 "12

可以简化写为: It can be simplified written as:

+ 2nBn cosPx + 2nBn cosPx

T 1 、2 1 T 1, 2 1

-0.093 -0.093

R R

上式表明,此DBR光纤激光器的输出拍频Av与增益光纤所在的弯曲半径R成函数关 The above equations show this DBR fiber laser output beat frequency and the gain Av bend radius R as a function of the optical fiber is located off

所以本发明,当传感光纤(增益光纤)处于不同的曲率半径R时,可以在频谱分析装置8处测量得到该正交偏振的单纵模DBR光纤激光器产生不同的拍频,并且拍频的平方随着弯曲半径平方的倒数成二次多项式变化。 Therefore the present invention, when the sensor fiber (gain fiber) at a different radius of curvature R, spectral analysis may be obtained at the measuring means 8 orthogonally polarized single longitudinal mode fiber DBR lasers produce different beat frequency, the beat frequency and with the bending radius squared inverse of the square of the quadratic variation.

5 5

Claims (2)

  1. 1.一种基于光纤激光器的弯曲半径测量仪,包括有:单模光纤(3),光波分复用器(4),其特征在于,还设置有光纤激光器(9),光纤泵浦源(5),隔离器(6),光电探测器(7),频谱分析装置(8),其中,所述的光纤激光器(9)通过单模光纤(3)与光波分复用器(4)连接,光波分复用器(4)分别通过单模光纤(3)与光纤泵浦源(5)以及隔离器(6)相连,隔离器(6)与光电探测器(7)、频谱分析装置(8)依次串联连接;其中所述的光纤激光器(9)采用DBR的线性腔结构,包括有传感光纤(1)和波长匹配的光纤光栅对(2),其中,传感光纤(1)连接在一对波长匹配的光纤光栅对(2)之间,所述的传感光纤(1)采用能由弯曲引起光纤双折射以至光纤激光器产生拍频变化的增益光纤构成。 A bend radius of fiber-based laser measuring instrument, comprising: a single mode fiber (3), an optical wavelength division multiplexer (4), characterized in that the further setting (9), an optical fiber with a fiber laser pump source ( 5), an isolator (6), a photodetector (7), spectral analysis means (8), wherein said fiber laser (9) by a single-mode fiber (3) and the optical wavelength division multiplexer (4) connected optical wavelength division multiplexer (4), respectively, by single-mode fiber (3) and the fiber pump source (5) and a separator (6) is connected to the separator (6) and the photodetector (7), spectral analysis means ( 8) are sequentially connected in series; wherein said fiber laser (9) of the DBR linear cavity structure, including sensor fiber (1) and a fiber grating for wavelength matching (2), wherein the sensor fiber (1) connector in an FBG wavelength matching between (2), said sensing fiber (1) can be caused by bending of the fiber as well as fiber lasers produce birefringence change in the beat frequency gain fiber configuration.
  2. 2. 根据权利要求1所述的基于光纤激光器的弯曲半径测量仪,其特征在于,所述的泵浦源(5)采用光纤泵浦激光器。 The fiber laser based bending radius measuring device according to claim 1, wherein said pump source (5) using optical fiber pump laser.
CN 200810052349 2008-02-29 2008-02-29 Bending radius measuring apparatus based on optical fibre laser CN100582658C (en)

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CN101893455A (en) * 2010-07-09 2010-11-24 哈尔滨工程大学 Optical fiber composite chamber laser feedback effect sensor and special demodulating method thereof
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CN1183548A (en) 1994-11-17 1998-06-03 阿尔卡塔尔电缆公司 Method for detecting and/or measuring physical quantity by distribution sensor
CN2708279Y (en) 2003-11-26 2005-07-06 南开大学 Optical fiber grating micro-oscillation sensing tester
CN1683903A (en) 2005-03-17 2005-10-19 上海交通大学 Method for simultaneously measuring bending curvature and bending direction

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1183548A (en) 1994-11-17 1998-06-03 阿尔卡塔尔电缆公司 Method for detecting and/or measuring physical quantity by distribution sensor
CN2708279Y (en) 2003-11-26 2005-07-06 南开大学 Optical fiber grating micro-oscillation sensing tester
CN1683903A (en) 2005-03-17 2005-10-19 上海交通大学 Method for simultaneously measuring bending curvature and bending direction

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