CN109632133A - A kind of temperature measuring device and method based on optical fiber - Google Patents

A kind of temperature measuring device and method based on optical fiber Download PDF

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Publication number
CN109632133A
CN109632133A CN201811644488.6A CN201811644488A CN109632133A CN 109632133 A CN109632133 A CN 109632133A CN 201811644488 A CN201811644488 A CN 201811644488A CN 109632133 A CN109632133 A CN 109632133A
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optical fiber
fiber
spectrum
temperature
interference
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李红
祝连庆
庄炜
徐滔
于明鑫
宋言明
娄小平
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Beijing Information Science and Technology University
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Beijing Information Science and Technology University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01KMEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/32Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres

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  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

本发明提供了一种基于光纤的温度测量装置及方法,包括以下步骤:(a)搭建七芯光纤和光纤球对称结构的马赫‑曾德尔干涉仪光路,全光纤马赫‑曾德尔干涉结构两端熔接光纤连接器,分别连接宽谱光源和光谱记录仪;全光纤马赫‑曾德尔干涉结构包括一段七芯光纤、第一单模光纤单端熔接光纤球和第二单模光纤单端熔接光纤球;(b)将所述全光纤马赫‑曾德尔干涉结构放入待测温度空间;(c)逐渐改变温度大小,记录不同温度下干涉透射谱,绘制干涉谱波谷峰值移动与温度大小的变化曲线;(d)通过所述干涉谱与温度变化曲线关系对外加温度进行测量。

The invention provides an optical fiber-based temperature measurement device and method, comprising the following steps: (a) building a Mach-Zehnder interferometer optical path with a seven-core optical fiber and a spherically symmetric structure of the optical fiber, and two ends of the all-fiber Mach-Zehnder interference structure Fusion-splicing optical fiber connectors, respectively connecting a broad-spectrum light source and a spectrum recorder; the all-fiber Mach-Zehnder interference structure includes a section of seven-core optical fiber, a first single-mode fiber single-end fusion-splicing fiber ball and a second single-mode fiber single-end fusion-splicing fiber ball (b) Put the all-fiber Mach-Zehnder interference structure into the temperature space to be measured; (c) gradually change the temperature, record the interference transmission spectrum at different temperatures, and draw the change curve of the peak shift of the interference spectrum and the temperature. ; (d) measure the applied temperature through the relationship between the interference spectrum and the temperature change curve.

Description

A kind of temperature measuring device and method based on optical fiber
Technical field
The present invention relates to a kind of full optical fiber interference fields of measurement, are based on seven core fibres and optical fiber ball pair in particular to one kind Claim the thermometry of Mach-Zender interferometer.
Background technique
In recent years, fibre optical sensor is detecting temperature, pressure, the physical quantitys such as curvature, refractive index and Biochemistry measurement field Concern by more and more researchers.For fibre optical sensor because of its electromagnetism interference, risk is small, compact dimensions, weight Gently, the at low cost and splendid characteristic of flexibility, with the adaptability of height in some special environment, so as to tested Physical parameter is accurately monitored.A kind of space interference of light system is proposed in 19th-century from roentgen Mach and Zeng Deer Since system, researcher realizes the measurement of a variety of physical quantitys with different optical fiber mach-zhender structures.Mach-Zehnder is dry The type fibre optical sensor of relating to has the characteristics that simple and light, to be easy to production, high sensitivity, sensing wavelength range big, for a long time with Come be researchers at home and abroad concern emphasis direction.Compared to space optical path, waveguide coupling or the cascade horse of fiber coupler Conspicuous-once moral interference system, integrated full optical fiber interference device were more convenient and easily fabricated.In recent years, optical fiber mode Formula interference, which is formed by Mach-Zehnder interferometer, becomes research hotspot, and the two-way of interference is formed in this Mach-Zehnder interferometer Light corresponds to two different transmission modes in optical fiber.For common single mode optical fiber, a kind of generally only transmission of basic mode Mode, researcher pass through dislocation welding, drawing cone, non-single mode optical fiber welding, thin-core fibers, photonic crystal fiber, hollow-core fiber The methods of be to realize Mach-Zehnder interference, and realize certain physics using its feature by basic mode energy coupling into cladding mode The measurement of amount.
With the development of optical fiber structure design and manufacture craft, seven core fibres are not only applicable to fiber optic communication, because it has The characteristics of interference condition is good, high sensitivity is used for sensory field by domestic and foreign scholars.Wherein, G.Salceda-Delgado is proposed Interference structure based on seven cores is used for curvature sensing/monitoring, and "-seven cores of single mode-single mode " type has been built based on seven core fibres Mach-Zehnder interference sensing structure, although the sensitivity of structure sensing is strong, the linear pass of wave length shift and Curvature varying Tie up to curvature it is smaller when show be not obvious.Zhou Song et al. proposes " single mode-- seven cores of multimode-multi-mode-single mode " temperature sensing knot Structure, can accurately measure 800 DEG C of test temperature, sensitivity and measurement range compared to traditional sensor has large increase, But the structure needs the splicing parameter of rationally control multimode fibre, it is more demanding to process.
Summary of the invention
The present invention provides the thermometry of a kind of seven core fibres and optical fiber ball asymmetric Mach-Zender that interferometer, institute It is high to state small measuring all -fiber Mach Zehnder interference structural volume, sound construction and measurement accuracy.
The present invention is realized by following technical solution:
A kind of temperature measuring device based on optical fiber, including interference structure, which is characterized in that the interference structure includes the The end of one single mode optical fiber and the second single mode optical fiber, first single mode optical fiber and the second single mode optical fiber is melted and molded as bead Shape forms single mode optical fiber-- seven core fibres of bead-bead-single mode optical fiber using one section of seven core fibre connection between two beads Structure;
First single mode optical fiber is connected with wide spectrum light source, and the second single mode optical fiber is connected with spectrum recorder.
It is further to improve, the wide spectrum light source be laser pump (ing) excite doped fiber generate spontaneous radiation wide spectrum optical or The spontaneous generation wide spectrum optical of laser diode.
It is further to improve, the small ball's diameter that first single mode optical fiber and the second single mode optical fiber end are melt into is 200~ 400um。
Further to improve, the length of seven core fibre is 9mm.
Further to improve, the first single mode optical fiber is connect by FC/APC connector with wide spectrum light source.
Further to improve, the second single mode optical fiber is connect by FC/APC connector with spectrum recorder.
A kind of thermometry based on optical fiber, which comprises the following steps:
Step 1) single mode optical fiber-- seven core fibres of bead-bead-single mode optical fiber structure interference structure is built, and connect Wide spectrum light source and spectrum recorder;
Step 2) interference structure is put into the temperature calibration case of temperature controllable;
Step 3) temperature level is gradually changed, the interference transmission spectrum under different temperatures is recorded, it is right to draw interference spectrum trough institute The curve that the optical wavelength answered changes with temperature level;
Step 4) interference structure is placed at temperature to be measured, it can be calculated according to interference spectrum to testing temperature.
It is further to improve, optical wavelength corresponding to the interference spectrum trough vary with temperature curve negotiating linear fit or Person's least square method is fitted.
The method for the principle of interference measurement temperature that the invention proposes a kind of using light, all -fiber Mach-in the present invention Zeng Deer interference structure is small in size, sound construction and measurement accuracy are high.
Detailed description of the invention
Fig. 1 shows seven core fibres and optical fiber ball asymmetric Mach-Zender that interferometer temperature measurement knot according to the present invention Structure schematic diagram;
Fig. 2 shows seven core fibres and optical fiber ball asymmetric Mach-Zender that interference welding schematic diagram;
Fig. 3 shows seven core fibres and optical fiber ball asymmetric Mach-Zender that interference structure and optical transport schematic diagram.
Fig. 4 shows the curve and linear relationship that interference spectrum in one embodiment of the invention changes with temperature level.
Specific embodiment
As depicted in figs. 1 and 2: 1 is wide spectrum light source in Fig. 1, and 2 be interference structure, mounted in the scale of thermometer of a temperature-controllable Determine in case, 3 be spectrum recorder, and 4 be transmission fiber, and 5 use thermometer for calibration or comparison.
In Fig. 2, the left side is single mode optical fiber and seven core fibre end face sectional views, and 7 fibre cores of seven core fibre are by one Central core and 6 away from 35 μm of the central core peripheral fibre core groups compositions in regular hexagon.What is selected in the present embodiment is Seven core fibre of SM-7C1500 (6.1/125) model of fibercore company, seven core fibre length are 9mm.
As shown in figure 3, all -fiber Mach Zehnder interference structure includes the first single mode optical fiber 6 and the second single mode optical fiber 10, The end of first single mode optical fiber 6 and the second single mode optical fiber 10 is melted and molded as coccoid (7 and 9), bead 7 and bead 9 Between connected using one section of seven core fibre 8.
All -fiber Mach Zehnder interference structure fabrication process: first single mode optical fiber is melted at one end using optical fiber splicer It is connected into spherical structure, is made another spare;Again by seven core fibres and the single mode optical fiber welding for having spherical structure, a fixed length is measured It spends (choosing 9mm in the present embodiment) and seven core fibres is truncated using optical fiber cutter, then be fused into another single mode optical fiber ball end Symmetrical structure forms the fibre-optic waveguide of " SMF-ball-SCF-ball-SMF ".
The working principle of the sensor are as follows: wide spectrum optical enters single mode optical fiber, is transmitted in the form of optical fiber basic mode, by first When optical fiber ball 7, launching efficiency is improved, and at mutation, a part of core mode, which is excited in covering, forms cladding mode, along packet Layer continues to transmit, and another part continues to propagate along the fibre core of seven core fibres 8, when reaching second optical fiber spherical structure 9, coupling effect Rate significantly improves, and cladding mode is again coupled into fibre core, is interfered with core mode, forms Mach-Zehnder interference.
Output transmission spectral intensity can indicate after Mach-Zehnder structure interferes are as follows:
In formula, k1And k2The respectively coefficient of coup of the transmission light when optical fiber spherical structure 7 and 9 transmits, η is cladding mode Transmission loss, IinIt is the light intensity of input light, Δ φ is the transmission through seven core fibre of interlude, the phase of core mode and cladding mode Potential difference
Since the propagation constant between different mode is different, after propagating same distance, different modes can generate phase Poor core mode and the phase difference of cladding mode generation are
When the interference effect that phase difference meets Δ φ=(2m+1) π (m is positive integer) Shi Fasheng destructive interference structure is saturating Penetrating spectrum trough wavelength may be expressed as:
In formula, Δ neffEffective refractive index for core mode and m rank cladding mode is poor, and L is the length of interferometer, and N is indicated The coefficient of phase difference when transmission spectrum is in trough.
Temperature sensing test is carried out using the transmission spectrum trough peak value drift of interferometer, when interferometer is influenced by temperature, The variation of optical path difference occurs for optical fiber at interference structure, and transmission spectrum can drift therewith.
Fig. 4 (a) is the transmission spectrum of fiber interference structure under different temperatures, is followed successively by 50 DEG C, 59 DEG C, 66.5 from left to right DEG C, 75.5 DEG C, 84 DEG C, 93.3 DEG C, 101.2 DEG C, 110.5 DEG C, 117.7 DEG C, the curve of spectrum at 126.4 DEG C.As can be seen that with The raising of temperature, interference spectrum is mobile to long wave length direction, carries out peak-seeking to the optical wavelength trough of spectrum trough, and by peak-seeking Value and spectral depth record and analyze the variation of temperature, this group of data are carried out with the linear fit of least square method, it is known that, Interference spectrum valley value varies with temperature linear variation.Temperature-wavelength formula is as follows:
In formula, m is damping peak order, and L is seven core fibre length, KTFor the coefficient of temperature and the relationship of wavelength change. Therefore the sensing characteristics be can use and carry out temperature test.
The calibration of temperature sensitivity coefficient:
Interference structure is put into temperature calibration case, records a spectrum at interval of 5 DEG C of variations, interfere the wavelength of trough with The raising of temperature is to long wave length direction drift.As shown in Fig. 4 (b), the linearity reaches 0.9855, and spectral depth is basically unchanged.Root The temperature at interference structure can be calculated by the corresponding wavelength of measurement spectrum trough according to the linear relationship.
The match parameter of associated fiber of the present invention is as shown in the table:

Claims (8)

1.一种基于光纤的温度测量装置,包括干涉结构,其特征在于,所述干涉结构包括第一单模光纤和第二单模光纤,所述第一单模光纤和第二单模光纤的末端均熔化成型为小球状,两小球之间采用一段七芯光纤连接,形成单模光纤-小球-七芯光纤-小球-单模光纤的结构;1. An optical fiber-based temperature measurement device, comprising an interference structure, wherein the interference structure comprises a first single-mode fiber and a second single-mode fiber, and the first single-mode fiber and the second single-mode fiber are The ends are melted and formed into small balls, and a section of seven-core optical fiber is used to connect the two small balls to form a structure of single-mode optical fiber-small ball-seven-core optical fiber-small ball-single-mode optical fiber; 第一单模光纤连接有宽谱光源,第二单模光纤连接有光谱记录仪。The first single-mode fiber is connected with a broad-spectrum light source, and the second single-mode fiber is connected with a spectrum recorder. 2.如权利要求1所述的一种基于光纤的温度测量装置,其特征在于,所述宽谱光源为激光泵浦激发掺杂光纤产生自发辐射的宽谱光或激光二级管自发产生宽谱光。2 . The optical fiber-based temperature measurement device according to claim 1 , wherein the broad-spectrum light source is a broad-spectrum light generated by a laser pumping and exciting a doped fiber to generate spontaneous radiation or a laser diode spontaneously generating a wide-spectrum light. 3 . spectral light. 3.如权利要求1所述的一种基于光纤的温度测量装置,其特征在于,所述第一单模光纤和第二单模光纤末端熔成的小球直径为200~400um。3 . The optical fiber-based temperature measurement device according to claim 1 , wherein the diameter of the spheres formed by melting the ends of the first single-mode optical fiber and the second single-mode optical fiber is 200-400 μm. 4 . 4.如权利要求1所述的一种基于光纤的温度测量装置,其特征在于,所述七芯光纤的长度为9mm。4 . The optical fiber-based temperature measurement device according to claim 1 , wherein the length of the seven-core optical fiber is 9 mm. 5 . 5.如权利要求1所述的一种基于光纤的温度测量装置,其特征在于,第一单模光纤通过FC/APC接头与宽谱光源连接。5 . The optical fiber-based temperature measurement device of claim 1 , wherein the first single-mode optical fiber is connected to the broad-spectrum light source through an FC/APC connector. 6 . 6.如权利要求1所述的一种基于光纤的温度测量装置,其特征在于,第二单模光纤通过FC/APC接头与光谱记录仪连接。6 . The optical fiber-based temperature measurement device of claim 1 , wherein the second single-mode optical fiber is connected to the spectrum recorder through an FC/APC connector. 7 . 7.一种基于光纤的温度测量方法,其特征在于,包括以下步骤:7. A temperature measurement method based on optical fiber, characterized in that, comprising the following steps: 步骤一)搭建单模光纤-小球-七芯光纤-小球-单模光纤结构的干涉结构,并连接宽谱光源和光谱记录仪;Step 1) Build an interference structure of a single-mode fiber-small ball-seven-core fiber-small ball-single-mode fiber structure, and connect a broad-spectrum light source and a spectrum recorder; 步骤二)将干涉结构放入可控制温度的温度标定箱中;Step 2) Put the interference structure into a temperature-controlled temperature calibration box; 步骤三)逐渐改变温度大小,记录不同温度下的干涉透射谱,绘制干涉谱波谷所对应的光波长随温度大小变化的曲线;Step 3) Gradually change the temperature, record the interference transmission spectrum at different temperatures, and draw a curve of the wavelength of light corresponding to the trough of the interference spectrum changing with the temperature; 步骤四)将干涉结构放在待测温度下,根据干涉谱即可计算出待测温度。Step 4) The interference structure is placed at the temperature to be measured, and the temperature to be measured can be calculated according to the interference spectrum. 8.如权利要求7所述的一种基于光纤的温度测量方法,其特征在于,所述干涉谱波谷所对应的光波长随温度变化曲线通过线性拟合或者最小二乘法进行拟合。8 . The method for measuring temperature based on an optical fiber according to claim 7 , wherein the curve of the change of light wavelength with temperature corresponding to the trough of the interference spectrum is fitted by linear fitting or least squares method. 9 .
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Application publication date: 20190416