CN1553158A - Optical fibre temperature sensing method and sensor based on SAGNAC interferometer - Google Patents

Optical fibre temperature sensing method and sensor based on SAGNAC interferometer Download PDF

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CN1553158A
CN1553158A CNA2003101133110A CN200310113311A CN1553158A CN 1553158 A CN1553158 A CN 1553158A CN A2003101133110 A CNA2003101133110 A CN A2003101133110A CN 200310113311 A CN200310113311 A CN 200310113311A CN 1553158 A CN1553158 A CN 1553158A
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fiber
polarization
polarization maintaining
temperature
sagnac interferometer
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CN100343637C (en
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杨远洪
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北京航空航天大学
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Abstract

In the present invention, a small section of polarization preserving fiber transducing head is added into closed light path of total polarization SAGNAC interferometer applying Y waveguide modulator and wide spectrum light source to create condition for generating polarization nonreciprocal after certain process is applied, generated polarization nonreciprocal phase-shift and temperature acted on transducing head is presented in linear ratio relationship when light path is in operation so phase shift can be measured accurately by utilizing circuit the same as used in close ring optical fibre gyro detection and furthermore temperature measurement is realized.

Description

基于SAGNAC干涉仪的光纤温度传感方法及其传感器 The method based on optical fiber temperature sensing SAGNAC interferometer and sensor

技术领域 FIELD

本发明涉及一种基于SAGNAC干涉仪的光纤温度传感方法及其传感器。 The present invention relates to an optical fiber temperature sensing method and a sensor based SAGNAC interferometer.

背景技术 Background technique

SAGNAC干涉仪是一种典型的干涉仪,是所有光学陀螺的基本结构,当用光纤形成其光路并配上专用检测电路后,便成为光纤陀螺,有关光纤陀螺的原理和技术可参见Herve C.Lefever(法)的专著《The Fiber-Optic Gyroscope》或其中译本:张桂才、王魏,《光纤陀螺仪》,下文的相关论述都将以此为基础。 SAGNAC interferometer is a typical interferometer, the basic structure of all optical gyroscope, an optical path which is formed when the optical fiber and coupled with a dedicated detecting circuit becomes FOG, FOG related principles and techniques can be found in Herve C. Lefever (France) monograph "the fiber-Optic gyroscope" or where the translation: Chang Cai, Wang Wei, "FOG", the following related discussion will be based. 图1为一种典型的SAGNAC干涉仪,宽谱光源1发出的宽谱光经光纤2到耦合器3再经光纤4进入Y波导调制器5,光经Y波导调制器5后被分成两路在光纤环7中沿相反的方向传输,光在光纤环中的传输时间为T(T=nL/C,n为光纤的等效折射率,L为光纤环长度,C为真空中的光速),这两路光再次在Y波导调制器5相遇并发生干涉,干涉光经光纤4、耦合器3、光纤9进入探测器10。 Figure 1 is a typical SAGNAC interferometer, a wide spectrum of broad-spectrum light emitted by the light source 2 to the optical coupler 4 through the optical fiber 3 and then into the Y waveguide modulator 5, the light waveguide Y through the modulator 5 into two ways after transmitted along the fiber loop 7 in the opposite direction, the transmission time of the light in the optical fiber ring is T (T = nL / C, n is the equivalent refractive index of the optical fiber, L is the length of the fiber loop, C is the light velocity in vacuum) , two Y branch optical waveguide modulator meet again at 5 and interference, interference light through the optical fiber 4, the coupler 3, the optical fiber 9 into the detector 10. 探测器10的输出电压为:V=k(1+cos(φs+φe)) (1)其中:k为与光强有关的常系数;φs为SAGNAC相移,φe为误差位相。 Output voltage of the detector 10 is: V = k (1 + cos (φs + φe)) (1) where: k is a constant related to light intensity coefficient; .phi.S phase shift is SAGNAC, φe is the phase error. 检测电路13用于检测总相位φs+φe。 Detection circuit 13 for detecting a total phase φs + φe. 在光纤陀螺中,检测电路采用一种闭环的检测技术实现位相的检测,通过方波调制、解调取得误差指示信号,通过改变数字阶梯波参数实现反馈,这已成为SAGNAC干涉仪位相检测的标准方法,其测量精度很高,已达到10-5~10-7rad的位相检测精度。 FOG, the detection circuit uses a closed-loop detection technology for detecting phase by square wave modulation, demodulation to obtain the error indication signal, the feedback realized by changing the parameters of the digital step waveform, which has become a standard SAGNAC interferometer phase detection method, the measurement accuracy is high, the phase has reached the detection accuracy of 10-5 ~ 10-7rad. 在光纤陀螺中,有用的信号是φs,误差信号是φe,必须加以抑制,为此,在陀螺光路中使用了保偏光纤以保证在光路中只有一个设定的单偏振模式传播。 FOG, the useful signal is .phi.S, error signal φe, must be suppressed, for use in the gyro polarization maintaining fiber optical path in the optical path to ensure that only a single set of polarization modes propagate.

保偏光纤是利用波导的形状双折射或应力双折射来实现偏振保持的。 PM fiber is the use of form birefringence or waveguide to achieve stress birefringence polarization maintaining. 现在广泛采用施加应力来实现双折射,即利用了一种热膨胀系数比石英大的附加材料在光纤中产生应力。 Now widely used to implement applying stress birefringence, i.e., using a thermal expansion coefficient than the stress in the optical fiber of quartz large additional material. 光纤预制棒是通过把两个高浓度掺杂的石英棒(通常采用硼、磷或铝)放置在芯区的两边而制成。 The optical fiber preform is obtained by two heavily doped quartz rod (usually boron, phosphorus or aluminum) is placed on both sides of the core region is made. 在高温下拉成光纤后,这两个高掺杂棒在冷却时收缩,但它们的热收缩量受到周围石英的影响,使高掺杂棒处于拉压力下,通过反作用使光传播所在的纤芯区产生应力:沿两个高掺杂棒的轴存在着一个拉应力作用,这个轴一般叫做慢轴;而沿与之正交的轴存在着一个压应力作用,这个轴一般叫做快轴。 After the temperature drop down into an optical fiber, these two highly doped bars shrink when cooled, but they are affected by the surrounding thermal contraction of quartz, the high-doped rod is under tensile stress, by the reaction so that light propagating the core is located area stress: in the two highly doped rod axis there is a tensile stress, commonly called the slow axis of the shaft; and an axis orthogonal to the existence of a compressive stress along therewith, the shaft is generally called the fast axis. 图2为三种最常用的保偏光纤的断面图,20为应力区,22为光纤芯,21为普通包层。 FIG 2 is a sectional view of the three most common polarization maintaining fiber, the stress zone 20, 22 of the fiber core, the cladding 21 is normal. 在“熊猫”型光纤中,高掺杂棒是圆的;在“领结”型光纤中,高掺杂区域形状象领结;在椭圆型光纤中,应力包层是椭圆的。 In the "panda" fiber type, highly doped rod is round; the "bow tie" type fiber, the bow tie shaped like a highly doped region; in the optical fiber elliptic stress cladding elliptical. 由于不同方向的应力不一样,导致光纤断面X和Y方向的等效折射率neqx,neqy不一样,其差为:Δnb=neqx-neqy其传输常数分别为:βx=2πneqxλ]]>βy=2πneqyλ]]>λ为传输光波长,当这束光在保偏光纤中传播时,将激起两传输常数分别为βx和βy的传播模式,它们在光纤中的传输时,由于传输常数不一样,随着传输距离的增加,其位相差将增大,当这个位相差对应的光程差大于所用光源的相干长度时,这两个模式相干时将失去对比度,此时对应的传输光纤长度被定义为干涉仪相干长度。 Since the stress in different directions are not the same, resulting in the fiber cross section of the X and Y directions equivalent refractive index neqx, neqy not the same, the difference is: Δnb = neqx-neqy its transmission constants were: & beta; x = 2 & pi; neqx & lambda;] ]> & beta; y = 2 & pi; neqy & lambda;]]> λ is the transmission wavelength of light, when the beam of light propagating in a polarization maintaining fiber, will stimulate two transmission constants of propagation mode βx and βy, which in the optical fiber when the transmission, since the propagation constant is not the same, as the transmission distance increases, which will increase the phase difference when the phase difference corresponding to an optical path difference greater than the coherence length of the light source used, the contrast will be lost when these two modes of coherent in this case the corresponding transmission fiber length is defined as the coherence length of the interferometer. 在光纤陀螺中要求只有一个偏振模式传播,尽管采用了保偏光纤以保证单偏振模式传输,但由于保偏光纤中存在缺陷,往往存在较多的模式偏振耦合,从而产生非互易相移,这种由保偏光纤偏振保持能力不理想产生的非互易被定义为偏振非互易(PNR)。 FOG requires only one polarization mode of propagation, despite the use of polarization maintaining fiber to ensure single polarization mode transmission, but because of defects in the polarization maintaining fiber, there is often more polarization mode coupling, resulting in a non-reciprocal phase shift, this partial non-polarization maintaining fiber by a retention capacity produce undesirable cross-polarization easily defined as the non-reciprocal (PNR). 这是影响光纤陀螺性能的重要误差源,由于PNR对光纤长度,应力区应力变化和偏振耦合系数都存在强的相关性,而这些参数对温度都很敏感,本发明中就是利用这种非互易的温度敏感性,通过设计特殊的参数和结构实现温度的传感。 This is an important source of error influence FOG performance, since for PNR fiber length, stress and stress regions polarization coupling coefficient exists a strong correlation, and these parameters are very sensitive to temperature, the present invention is the use of such a non-reciprocal temperature sensitivity is easy to achieve by designing a special temperature sensing parameters and structures.

发明内容 SUMMARY

本发明的技术解决问题:提供一种能精确传感温度的基于SAGNAC干涉仪的光纤温度传感方法及其传感器。 The technical problem of the present invention: to provide a precise temperature sensing SAGNAC interferometer-based optical fiber temperature sensing method and the sensor.

本发明的技术解决方案是:基于SAGNAC干涉仪的光纤温度传感方法,其特征在于:将保偏光纤传感头加入采用Y波导调制器和宽谱光源的全保偏SAGNAC干涉仪的闭合光路中,通过保偏光纤与保偏光纤延迟环和Y波导调制器连接,在连接点,相连的保偏光纤的偏振主轴互相交成一设定角,当温度场作用在这段光纤时,在其中会产生的偏振非互易相移,这个相移与作用在传感头上的温度成线性比例关系,采用与光纤陀螺相同的位相检测电路测量这种由温度引起的相移,从而实现温度的测量。 Technical solutions of the present invention is: an optical fiber temperature sensing method based SAGNAC interferometer, comprising: a polarization maintaining fiber sensing head added closed light path Y waveguide modulator using a broad spectrum light source and a polarization maintaining full SAGNAC interferometer , the delay through the polarization maintaining fiber and a polarization maintaining fiber ring and the Y-waveguide modulator is connected, at the connection point, connected to the polarization main axes of the polarization maintaining fiber cross each other at an angle set, when the temperature in this field optical effect, in which It will produce nonreciprocal polarization phase shift, the phase shift effect at a temperature sensing linearly proportional to the head, using the same FOG this phase detection circuit measures the phase shift due to temperature, the temperature in order to achieve measuring.

采用上述方法实现的基于SAGNAC干涉仪的光纤温度传感器,其特征在于:它由宽谱光源、探测器,保偏光纤耦合器、Y波导调制器、保偏光纤延迟环、信号检测电路组成传感器的主体,和保偏光纤传感头通过保偏光纤相连形成全保偏的SAGNAC干涉仪的温度传感器组成,在与传光保偏光纤的连接点,相连的保偏光纤的偏振主轴互相交成一设定角。 SAGNAC interferometer-based optical fiber sensors are implemented method described above, characterized in that: it consists of a broad spectrum light source, a detector, a polarization maintaining fiber coupler, Y waveguide modulator, polarization-maintaining fiber delay loop, the sensor signal detecting circuit body, and a polarization maintaining fiber optic sensing head linked to form a SAGNAC interferometer full polarization maintaining the temperature sensors through a polarization maintaining fiber, with the transmission light polarization maintaining fiber connecting point, the polarization of the spindle connected to the PM fiber intersect with each other into a set fixed angle.

本发明与现有技术相比具有的优点是:利用全保偏SAGNAC干涉仪的偏振非互易相移的温度敏感性实现温度的传感,同时采用成熟、通用的闭环光纤陀螺的位相检测技术进行信号检测,实现了温度的测量。 As compared to the prior art and the present invention has the advantage that: SAGNAC interferometer using the polarization maintaining full polarization analyzer non-reciprocal phase shift to achieve the temperature sensitivity of the temperature sensor, while the mature, phase detection techniques common loop FOG signal detection, to achieve a temperature measurement. 由于SAGNAC干涉仪具有很好的互易性,因此这种方法具有很好的抗干扰能力;由于采用相位检测技术检测精度高且测量动态范围大、线性度好,因此本方法可实现高精度,优于0.01℃,和大范围:-200℃~+400℃的温度测量。 Since SAGNAC interferometer having good reciprocity, so this method has a good anti-jamming capability; high because the detection accuracy of the phase detection and the measurement dynamic range, good linearity, and therefore the method can be implemented with high accuracy, than 0.01 ℃, and a wide range of: measuring a temperature of -200 ℃ ~ + 400 ℃ of.

附图说明 BRIEF DESCRIPTION

图1为现有的光纤陀螺用SAGNAC干涉仪结构图;图2为本发明采用的保偏光纤结构示意图;图3为本发明的结构示意图; FIG 1 is a conventional fiber optic gyro configuration diagram SAGNAC interferometer; structural diagram of the polarization maintaining fiber used in the present invention, FIG. 2; FIG. 3 is a schematic structural diagram of the invention;

图4为本发明中相干偏振光传输路径示意图。 4 of the present invention in FIG polarized coherent transport path schematic.

具体实施方式 Detailed ways

如图3所示,本发明由宽谱光源25、耦合器27、Y波导调制器29、保偏光纤延迟环31、保偏光纤传感头33、探测器38和信号检测电路40组成基于SAGNAC干涉仪的光纤温度传感器。 3, the present invention is the broad spectrum optical source 25, a coupler 27, Y waveguide modulator 29, a polarization maintaining fiber ring delay 31, PM fiber sensing head 33, the detector 38 and a signal detecting circuit 40 based composition SAGNAC instrument interferometric fiber optic temperature sensor. 宽谱光源由超辐射二极管SLD,或发光二极管ELED,或宽带掺铒光源SFS及其驱动电路组成,光路中所有器件由保偏光纤连接,保偏光纤传感头33长度小于干涉仪的相干长度,本发明实施例中取保偏光纤传感头光纤长度<50mm,它通过保偏光纤32和光纤35与保偏光纤延迟环31和Y波导调制器29相连,在两个连接点34a和34b,相连的两根光纤的偏振轴(即X轴或Y轴)互相交叉成一个角度θ且0°<θ<90°,优选可以为45°,这时效果最好。 Broad-spectrum superluminescent diode light source consists of the SLD, ELED or light emitting diode, or a broadband erbium-doped SFS source and a driving circuit, all of the light path from the polarization maintaining optical fiber connection devices, PM fiber sensing head 33 shorter than the coherence length of the interferometer embodiment, the present invention in partial bail optical fiber sensor head length <50mm, which is connected to the optical fiber 32 and the optical fiber 35 and the polarization maintaining fiber delay loop 31 and the Y-waveguide 29 through the polarization modulator, the two connection points 34a and 34b, polarization axes of two optical fibers connected to (i.e., X-axis or Y-axis) cross each other at an angle [theta] and 0 ° <θ <90 °, preferably may be 45 °, the best case. 当通过接触或辐射,有温度场作用在保偏光纤传感头33上时,在SAGNAC干涉仪中将通过偏振非互易效应产生正比于温度的非互易位相变化,通过信号检测电路40测出这个位相变化,再乘一个系数便可得到测量的温度值。 When radiation or by contact, temperature during polarization field acting on the fiber-optic sensing head 33, the instrument will produce easily SAGNAC interferometer non-reciprocal phase variation is proportional to the temperature of the nonreciprocal polarization by the effects, measured by the signal detection circuit 40 this change in the phase, and then by a factor of measured temperature can be obtained.

本发明的温度传感器由两部分组成,第一部分为图3中方框内部分,它宽谱光源25、耦合器27、Y波导调制器29、保偏光纤延迟环31、探测器38和信号检测电路40组成,光学器件由保偏光纤26、28、30、36连接,电路部分由屏蔽电缆连接;第二部分为温度传感部分,由保偏光纤32、保偏光纤35及保偏光纤传感头33组成,保偏光纤传感头33通过保偏光纤32和35分别与保偏光纤延迟环31和Y波导调制器29连接,在两个连接点34a和34b,相连的两根光纤的偏振轴(即X轴或Y轴)互相交叉成一个角度θ且0°<θ<90°,优选可以为45°,保偏光纤32和保偏光纤35只起传光的作用,有温度作用时,只有保偏光纤传感头33会产生PNR相移,保偏光纤传感头33为通过采用施加应力来实现双折射的保偏光纤,其长度小于干涉仪的相干长度,本发明实施例中取保偏光纤传感头光纤长度<50mm。 The temperature sensor according to the present invention consists of two parts, a first part of the frame part of Figure 3 Chinese, which wide spectrum light source 25, a coupler 27, Y waveguide modulator 29, a polarization maintaining fiber ring delay 31, the detector 38 and a signal detecting circuit 40. the optical device 26,28,30,36 is connected by a polarization maintaining fiber, a shielded cable connected to the circuit portion; the temperature sensing portion into the second portion, the polarization maintaining fiber 32, a polarization maintaining fiber 35 and the polarization maintaining fiber optic sensing 33. the first polarization maintaining fiber sensing head 33 via a polarization maintaining fiber 32 and 35 are respectively connected to the ring delay 29 and the Y-waveguide modulator 31 with polarization maintaining fiber, the two connection points 34a and 34b, two polarizing fibers connected to axis (i.e., X-axis or Y-axis) cross each other at an angle [theta] and 0 ° <θ <90 °, preferably may be 45 °, polarization effect of the optical fiber 32 and the polarization maintaining fiber 35 from transmitting light, the temperature effect when , only the polarization maintaining fiber sensing head 33 will produce a phase shift PNR, PM fiber sensing head 33 is achieved by the birefringence polarization maintaining fiber using the application of stress, the length of which is less than the coherence length of the interferometer, embodiments of the present invention partial bail optical fiber sensor head length <50mm.

宽谱光源25由超辐射二极管SLD,或边发光二极管ELED,或宽带掺铒光源SFS及其驱动电路组成;耦合器27为普通的全保偏3dB耦合器;Y波导调制器29为光纤陀螺专用的Y波导调制器,在光路中起分、合光,起偏和位相调制的作用,点J为分支点,又为合光点;保偏光纤延迟环31由保偏光纤绕制而成,光纤长度根据成本和信号检测系统的要求而定,一般为100~500米,其绕制方式与线绕电阻的绕制方法一样,其绕制原则是保证光纤环围成的等效的闭合面积为零,从而保证由SAGNAC效应引入的位相为零;探测器38为普通的探测器组件;信号检测电路40采用闭环光纤陀螺信号检测电路,其输入为探测器38的输出,通过电缆39相连,调制信号通过电缆41加到Y波导调制器29上,通过数据线42输出为数字量,可以直接通过显示接口电路和显示器直接显示。 Broad spectrum light source 25 by a superluminescent diode SLD, a light emitting diode or an edge ELED, or broadband erbium-doped SFS source and a driving circuit; a coupler 27 as a normal full 3dB coupler polarization; the Y waveguide modulator 29 to a dedicated fiber optic gyroscope Y-waveguide modulator, in the optical path from points, combined light, the polarizer and the phase modulation effect, the point J is the branch point, but also for co-spot; polarization maintaining fiber delay loop 31 of polarization maintaining fiber around the system, fiber length according to the requirements and the cost of signal detection system, typically 100 to 500 meters, which is about a method of winding wire wound resistors made of the same embodiment and its principle is to ensure that the fiber winding ring surrounded by the closed area equivalent zero, thereby ensuring the introduction of a zero phase SAGNAC effect; detector assembly 38 is a conventional detector; signal detecting circuit 40 uses closed-loop FOG signal detecting circuit which inputs the output of the detector 38 is connected by a cable 39, Y modulation signal applied to the modulator waveguide 41 via a cable 29, through the output line 42 to digital data can be directly displayed on the display directly to an interface circuit and a display. 也可通过任意的标准接口输出,一般采用标准232接口。 It may be output through any standard interface, generally 232 interface standard.

宽谱光源25发出的宽谱光经光纤26到耦合器27被一分为二,一部分再经光纤28进入Y波导调制器29,另一部分经光纤37从空头输出,光经Y波导调制器29后,在其分支点J再分两路并被起偏,其偏振方向与X轴平行,设为X轴偏振光,一路X偏振光沿顺时针方向传播,经光纤30、延迟光纤环31、光纤32通过节点34a进入传感头33,由于存在交叉角θ,X轴偏振光有一部分耦合进Y轴成为Y轴偏振光,X和Y轴偏振光在节点34b将再次发生模式耦合,即有一部分X轴偏振光耦合成为Y轴偏振光,一部分Y轴偏振光耦合成为X轴偏振光,这些光沿光纤35回到Y波导调制器29的合光点J;另一路X偏振光沿逆时针方向传播,将经历相同的光路和发生相同的偏振耦合并回到Y波导调制器29的合光点J并与顺时针传播的光发生干涉,此时Y波导调制器19为检偏器,它只允许X方向的偏振光通过并发生干涉。 Broad spectrum light source 25 emits a broad spectrum of light through the optical fiber 26 to the coupler 27 is divided into two, and then the portion of the optical fiber 28 into the Y waveguide modulator 29, the optical fiber 37 through another portion of the output from the short optical waveguide modulator 29 via Y after the branch point J at which the two routes and then a polarizer, whose polarization direction is parallel to the X axis, X axis polarized light propagating along X-polarized light in the clockwise direction, the optical fiber 30, a delay fiber loop 31, 34a into the fiber 32 via node sensing head 33, due to the presence of the crossing angle [theta], X-axis polarization is coupled with a portion of the Y-Y axis into the polarization axis, X-axis and Y-polarization mode coupling will occur again in the node 34b, that is portion of the X axis becomes the Y-axis polarized polarization coupling, the coupling portion of the Y-axis the X-axis polarization-polarized, the light along the optical fiber 35 back to the engagement point Y light waveguide modulator 29 is J; X-polarized light in the counterclockwise direction other way the direction of propagation, the same optical path and undergo the same polarization coupling occurs back and Y bonded spot waveguide modulator J 29 and interfering with the clockwise propagating light occur, then Y waveguide modulator 19 to analyzer, it only the X-direction and polarized light by interference. 图4为相干偏振光在光路中的传输和演变情况,图中只画出了最终能发生干涉的光分量,即从J点出发,偏振方向为X,回到J点,偏振方向仍为X的光,共有4束,分别为顺时针传输的光束45、光束46和逆时针传输的光束47、光束48。 FIG 4 is a coherent evolution and transmission of polarized light in the optical path, shown herein as a final interference light components can occur, i.e., from the point J, the polarization direction X, back to the point J, the polarization direction remains X light, a total of four beams, each light beam 45 transmitted clockwise, and counterclockwise light beams 46 transmission 47, the beam 48. 设J点沿顺时针方向到34a点的距离为L1,J点沿逆时针方向到34b点的距离为L2。 Disposed clockwise from point J to point 34a is L1, J point 34b in the counterclockwise direction to the distance from the point of L2. 保偏光纤传感头的长度为L,则光束45、光束46、光束47、光束48经历的光程分别为:45:&phi;xxxcw=&beta;xL1+&beta;xL+&beta;xL2]]>46:&phi;xyxcw=&beta;xL1+&beta;yL+&beta;xL2]]>47:&phi;xxxccw=&beta;xL2+&beta;xL+&beta;xL1]]>48:&phi;xyxccw=&beta;xL2+&beta;yL+&beta;xL1]]>可以看出,光束45和光束47、光束46和光束48所经历的光程相同,是互易的,对温度不敏感;而光束45和光束48、光束46和光束47所经历的光程不同,但其位相差相等,可被认为是一种情况,产生位相差的原因是光束46和光束48经历了长度为L的Y轴传播后又回到X轴,这就是PNR效应,产生的非互易相移为:φe=φxxx+φxyx=L(βx-βy)定义Δβ=βx-βy上式应改写为:φe=L·Δβ在保偏光纤中,Δβ在-200℃~+400℃的范围内与温度成反比,其系数约为10-3,光纤长度与温度成正比,系数约为10-6,设被测温度为T,Δβ和光纤长度的温度系数分别为C1和C2 Polarization maintaining fiber length sensor head is L, the beam 45, beams 46, beam 47, the beam 48 undergoes an optical path, respectively: 45: & phi; xxxcw = & beta; xL1 + & beta; xL + & beta; xL2]]> 46: & phi; xyxcw = & beta; xL1 + & beta; yL + & beta; xL2]]> 47: & phi; xxxccw = & beta; xL2 + & beta; xL + & beta; xL1]]> 48: & phi; xyxccw = & beta; xL2 + & beta; yL + & beta; xL1]]> As can be seen, beam 45 and beam 47, beam 46 and beam 48 experiences optical path same, are reciprocal, not sensitive to temperature; and beam 45 and beam 48, the beam 46 and beam 47 experience different optical path, but the phase difference is equal to, can be considered as a case, causes the phase difference of the light beam 46 and the beam 48 is subjected to a length L of the Y-axis and then back propagation X axis, which is PNR effect, non-generating reciprocal phase shift: φe = φxxx + φxyx = L (βx-βy) defined Δβ = the βx-βy formula should be rewritten as: φe = L · Δβ polarization maintaining fiber , Delta] [beta in the range of -200 ℃ ~ + 400 ℃ is inversely proportional to temperature, which coefficient is about 10-3, the fiber length is proportional to the temperature coefficient of about 10-6, provided the measured temperature T, Δβ and fiber length temperature coefficient C1 and C2, respectively 传感头33保偏光纤在温度T0时的长度为L0,Δβ的初始值为Δβ0,由上式有:φe=Δβ0L0[1+C1(T-T0)][1+C2(T-T0)]忽略二阶小量和小系数,可得到温度T值:T=A·φe+B其中:A=1/Δβ0L0C1,B=(C1T0-1)/C1。 A polarization maintaining fiber sensor head 33 at a temperature of at T0 length L0, Δβ initial value Δβ0, by the above formula has: φe = Δβ0L0 [1 + C1 (T-T0)] [1 + C2 (T-T0) ] ignore small and small coefficients of second order, to obtain the temperature value T: T = A · φe + B where: A = 1 / Δβ0L0C1, B = (C1T0-1) / C1.

从上式可看出,PNR相移φe与温度成线性比例关系,当有温度场通过接触或辐射作用在传感头上时,在SAGNAC干涉仪中将产生比例于温度的非互易位相变化,通过信号检测电路40测出位相变化,通过线性变换便可得到测量的温度值。 As can be seen from the above equation, the PNR φe phase shift is linearly proportional to temperature, when the non-reciprocal phase-change easily the temperature field by contact or sensing radiation at the head, in a proportion to produce a temperature-SAGNAC interferometer , the signal detection circuit 40 detect phase-change, can be obtained by linear transformation of the measured temperature value.

Claims (8)

1.一种基于SAGNAC干涉仪的光纤温度传感方法,其特征在于:将保偏光纤传感头加入采用Y波导调制器和宽谱光源的全保偏SAGNAC干涉仪的闭合光路中,通过保偏光纤与保偏光纤延迟环和Y波导调制器连接,在连接点,相连的保偏光纤的偏振主轴互相交成一设定角,当温度场作用在这段光纤时,在其中会产生的偏振非互易相移,这个相移与作用在传感头上的温度成线性比例关系,采用与光纤陀螺相同的位相检测电路测量这种由温度引起的相移,从而实现温度的测量。 A SAGNAC interferometer-based optical fiber temperature sensing device of the method, wherein: a polarization maintaining fiber sensing head was added using a closed light path Y interferometer waveguide modulator and a broad spectrum light source SAGNAC All PM by Paul partial polarization-maintaining fiber and the optical fiber delay loop is connected and the Y-waveguide modulator, at the connection point, connected to the polarization main axes of the polarization maintaining fiber cross each other at an angle set, when the temperature in this field optical effect, generated in which the polarization nonreciprocal phase shift, the phase shift effect at a temperature sensing linearly proportional to the head, using the same FOG this phase detection circuit measures the phase shift due to temperature, enabling measurement of temperature.
2.根据权利要求1所述的基于SAGNAC干涉仪的光纤温度传感方法,其特征在于:保偏光纤传感头为通过采用施加应力来实现双折射的保偏光纤,所述的保偏光纤传感头长度小于干涉仪的相干长度。 According to claim 1 SAGNAC interferometer-based optical fiber temperature sensing device of the method, wherein: PM fiber birefringence sensor head is achieved by using polarization maintaining fiber stress is applied to the polarization maintaining fiber sensor head shorter than the coherence length of the interferometer.
3.根据权利要求1所述的基于SAGNAC干涉仪的光纤温度传感方法,其特征在于:所述的设定角大于0°,小于90°。 3. The method of temperature sensing optical fiber based SAGNAC interferometer, wherein according to claim 1: said setting angle is greater than 0 °, less than 90 °.
4.根据权利要求1或3所述的基于SAGNAC干涉仪的光纤温度传感方法,其特征在于:所述的设定角优选为45°。 The fiber optic temperature sensor based SAGNAC interferometer of claim 1 or claim 3, wherein: said angle is preferably set to 45 °.
5.一种采用权利要求1所述方法实现的基于SAGNAC干涉仪的光纤温度传感器,其特征在于:它由宽谱光源、探测器,保偏光纤耦合器、Y波导调制器、保偏光纤延迟环、信号检测电路组成传感器的主体,和保偏光纤传感头通过保偏光纤相连形成全保偏的SAGNAC干涉仪的温度传感器组成,在与传光保偏光纤的连接点,相连的保偏光纤的偏振主轴互相交成一设定角。 Fiber optic temperature sensor based on the SAGNAC interferometer 1 5. A method as claimed in claim implemented using, characterized in that: it consists of a broad spectrum light source, a detector, a polarization maintaining fiber coupler, Y waveguide modulator, polarization maintaining fiber delay body ring, the sensor signal detection circuit, and a polarization maintaining fiber coupled to sensor head forming a full polarization maintaining SAGNAC interferometer temperature sensors via a polarization maintaining fiber, the polarization maintaining fiber and the connection point of the partial transmission light protection, connected cross polarization main fiber into a set angle to each other.
6.根据权利要求5所述的基于SAGNAC干涉仪的光纤温度传感器,其特征在于:保偏光纤传感头为通过采用施加应力来实现双折射的保偏光纤,其长度小于干涉仪的相干长度。 6. The optical fiber temperature sensor based SAGNAC interferometer as claimed in claim 5, wherein: PM fiber birefringence sensor head is achieved by using polarization maintaining fiber stress is applied, the length of which is less than the coherence length of the interferometer .
7.根据权利要求5所述的基于SAGNAC干涉仪的光纤温度传感器,其特征在于:所述的设定角大于0°,小于90°。 7. The optical fiber temperature sensor 5 based on the SAGNAC interferometer according to claim wherein: said setting angle is greater than 0 °, less than 90 °.
8.根据权利要求5或7所述的基于SAGNAC干涉仪的光纤温度传感器,其特征在于:所述的设定角优选为45°。 Fiber optic temperature sensor based SAGNAC interferometer according to claim 5 or 7, wherein: said angle is preferably set to 45 °.
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