Optical fiber temperature sensor, temperature testing system and temperature testing method

Abstract

The application discloses a fiber temperature sensor, a temperature testing system and a temperature testing method. The fiber F-P cavity is prepared by etching a single-mode optical fiber. The optimal depth of the fiber F-P cavity is H=73.3 microns; the optimal length of the fiber F-P cavity is L=46.3 microns; and the end face inclination angle of the fiber F-P cavity is θ<1.3°. When the temperature of the fiber F-P cavity temperature sensor changes, the fiber F-P cavity appearance changes, thereby causing the spectrum signal to shift. The actual relationship between the spectrum shift and the temperature change is determined, and the linear relationship between the temperature and the wavelength shift is converted, thereby forming the fiber F-P cavity temperature sensor. The application has the advantages of good optical performance, stability, small volume and the like, and can be used for high-precision temperature measurement in strong electromagnetic radiation, flammable and explosive and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber temperature sensors, and in particular to an optical fiber temperature sensor, a temperature testing system and a temperature testing method. BACKGROUND

[0002] Temperature is an important physical quantity indispensable for scientific research, industrial production and daily life. The perception and detection of temperature need to be realized through temperature sensors. With the progress of science and technology, various new types of temperature sensors have been gradually derived, but most of them have problems such as complex structure, low measurement accuracy and long-term drift, which are difficult to meet the actual application requirements. Using optical fiber temperature sensors to measure temperature has the advantages of anti-electromagnetic interference ability, electrical insulation performance, accurate measurement and ability to work in a relatively complex environment. SUMMARY

[0003] Therefore, the present application provides an optical fiber temperature sensor, a temperature testing system and a temperature testing method, which can solve the problems of low accuracy, low linearity and slow response speed of existing optical fiber temperature sensors.

[0004] In a first aspect, the present application provides an optical fiber temperature sensor having an optical fiber F-P cavity, wherein the optical fiber F-P cavity is a concave cavity etched on a single-mode optical fiber.

[0005] Optionally, the depth of the optical fiber F-P cavity is 70 μm<H<75 μm.

[0006] Optionally, the length of the optical fiber F-P cavity is 45 μm<L<60 μm.

[0007] Optionally, the optical fiber F-P cavity is an inverted trapezoid, and the inclination angle θ of the end face is <1.3°.

[0008] Optionally, the core diameter of the cladding of the single-mode optical fiber is 9 μm.

[0009] Optionally, the core diameter of the cladding of the single-mode optical fiber is 125 μm.

[0010] In a second aspect, the present application provides a temperature testing system, comprising a heating platform, an optical fiber modem, a processor and an optical fiber temperature sensor as described above.

[0011] The heating platform is used to heat the optical fiber F-P cavity, the optical fiber modem is optoelectronically connected to the optical fiber F-P cavity through a single-mode optical fiber, and the optical fiber modem is connected to the processor.

[0012] Optionally, the optical fiber modem is a GM8050 optical fiber modem.

[0013] In a third aspect, the present application provides a temperature testing method, which is implemented by using the above-mentioned temperature testing system.

[0014] Optionally, the implemented process comprises the following steps:

[0015] Step 1: measure the length L, depth H, and end face tilt angle of the fiber F-P cavity;

[0016] Step 2: heat the fiber F-P cavity by using a heating platform;

[0017] Step 3: connect the fiber F-P cavity to a fiber modulator by using a fiber adapter;

[0018] Step 4: measure the reflected interference light power by using the modulator, and collect data, optimize algorithms, and save by using a computer;

[0019] Step 5: as the temperature rises, the interference spectrum shifts to the long wave direction, determine the actual relationship between the spectrum shift and the temperature change, and convert it into a linear relationship between the temperature and the wavelength shift, to form a fiber F-P cavity temperature sensor.

[0020] Compared with the prior art, the present application has at least the following technical effects or advantages:

[0021] 1. The present application etches a concave cavity on a single-mode optical fiber to prepare a fiber F-P cavity, which has a smooth inner wall, excellent anti-interference performance, good repeatability, and stability.

[0022] 2. The present application provides a temperature testing method, which can collect data, optimize algorithms, and improve the precision and linearity of the fiber F-P cavity.

[0023] In summary, the technical solution of the present application overcomes the shortcomings of low precision and linearity, and realizes the measurement in a complex environment. Compared with traditional electronic temperature sensors, the present application has good anti-interference ability, fast response speed, and convenient measurement, and provides a reference for other temperature sensors.

[0024] In the era of intelligence, real-time, and integration, the popularization and use of the technical solution of the present application meet the needs of temperature measurement. BRIEF DESCRIPTION OF DRAWINGS

[0025] The technical solution of the present application and other beneficial effects will become apparent through the following detailed description of the specific embodiments of the present application in combination with the accompanying drawings.

[0026] Figure 1 Fig. 1 schematically shows the structure of a fiber F-P cavity of the present application;

[0027] Figure 2A temperature sensing fiber F-P cavity measurement method of the application is schematically shown in the figure.

[0028] Figure 3 A temperature sensing fiber F-P cavity wavelength-power diagram of the application is schematically shown in the figure.

[0029] Figure 4 A temperature sensing fiber F-P cavity temperature-wavelength linear relationship diagram of the application is schematically shown in the figure.

[0030] In the figure, the elements are identified as follows:

[0031] 1-fiber F-P cavity; 1a-first end face; 2a-second end face; 2-single mode fiber; 3-fiber modem; 4-PC; 5-heating platform. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the application.

[0033] In the description of the application, it should be understood that the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0034] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or electrically connected or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0035] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0036] Please refer to Figure 1 The optical fiber temperature sensor of the present application has an optical fiber F-P cavity 1, which is a concave cavity etched on a single-mode optical fiber 2.

[0037] As an etching method for making the optical fiber F-P cavity 1, a femtosecond laser can be used to etch a concave cavity on the single-mode optical fiber 2.

[0038] Again, please refer to Figure 1 The concave cavity of the above-mentioned optical fiber F-P cavity 1 has three parameter indicators: cavity depth H, cavity length L, and end face inclination angle θ, which will affect the optical reflection performance of the optical fiber F-P cavity 1.

[0039] Specifically, the depth of the optical fiber F-P cavity 1 is 70 μm<H<75 μm, at which the reflected power is relatively large and tends to be stable. Further, the optimal depth is H=73.3 μm, at which the reflected power reaches a maximum value.

[0040] The length of the optical fiber F-P cavity 1 is 45 μm<L<60 μm, at which the reflected light power intensity is relatively large and the change amplitude is small. The optimal length L=46.3 μm, at which the reflected light power intensity is the largest.

[0041] The optical fiber F-P cavity 1 can be an inverted trapezoid, and the end face inclination angle θ<1.3°, at which the reflected light power intensity is relatively large.

[0042] As an exemplary illustration, the diameter of the single-mode optical fiber 2 core is 9 μm, and the diameter of its cladding is 125 μm.

[0043] The model of the optical fiber modem 3 selected can be a GM8050 optical fiber modem 3, which can have a built-in light source.

[0044] Now the reflection process of the above-mentioned optical fiber F-P cavity 1 on light is introduced. When the input light enters the optical fiber, the first reflection occurs at the first end face 1a of the cavity, forming reflected light; the remaining part passes through to the second end face 2a of the cavity to form the second reflection, forming secondary reflected light. The two reflected lights interfere to form an interference spectrum.

[0045] Please refer to Figure 2 , the temperature testing system comprises a heating platform 5, a fiber modulator 3, a processor and a fiber temperature sensor as described above.

[0046] Here, the temperature testing system is used to explore the temperature characteristics of the sensor, and the fiber F-P cavity is subjected to temperature sensing experiments.

[0047] The processor can be any device with a processor, such as a PC 4, a smart mobile terminal, a server, etc.

[0048] As an exemplary illustration, the heating instrument uses a JF-966 microcomputer heating platform 5 with a temperature range of 0-500℃, which can manually adjust the temperature size. One end of the fiber F-P cavity sensing probe is placed on the microcomputer heating platform 5, and the other end is connected to the GM8050 fiber modulator through the fiber adapter, and the demodulator and the computer are connected. The reflected interference signal is detected by the GM8050 modulator, and the detection data is transmitted to the computer. The computer collects data, optimizes algorithms and saves them.

[0049] The specific process of implementing the test using the above temperature testing system includes the following steps:

[0050] (1) The length L, depth H and end face inclination angle of the fiber F-P cavity 1 are measured by a confocal microscope.

[0051] (2) The fiber F-P cavity 1 that meets the design requirements is placed on the heating platform 5. The base temperature is set to 0℃, the temperature range is 0-500℃, the temperature interval is 0.2℃, and the temperature is controlled.

[0052] (3) The fiber F-P cavity 1 is connected to the GM8050 fiber modulator 3 through the fiber adapter, the test wavelength range is 1528nm-1568nm, and the wavelength resolution is 0.1pm.

[0053] (4) The reflected coherent light power is measured by the fiber modulator 3, and the data is collected, algorithmically optimized and saved by the PC 4.

[0054] (5) As the temperature rises, the interference spectrum shifts to the long wave direction, the actual relationship between the spectrum shift and the temperature change is determined, and it is converted into a linear relationship between temperature and wavelength shift, forming a fiber F-P cavity 1 temperature sensor.

[0055] Please refer to Figure 3 , Figure 4The specific operation of the above test is demonstrated as follows: first, set the base temperature to 0℃, the temperature range of the optical fiber F-P cavity 1 is 0-500℃, the temperature interval is 0.2℃, and the temperature rising and falling experiment is performed. When the set temperature is reached, the spectrum data is read after the temperature is stable, and a plurality of groups of data are collected in total, such as Figure 3 As shown in the figure. When the temperature is 0-500℃, the interference spectrum shifts to the long wave direction with the temperature rising. By determining the actual relationship between the spectrum shift and the temperature change, and converting it into the linear relationship between the temperature and the wavelength shift, the temperature sensor with the optical fiber F-P cavity 1 is formed.

[0056] It is worth noting that the present application has the following intellectual contributions to the prior art:

[0057] 1. The present application etches a concave cavity on a single-mode optical fiber 2 to prepare an optical fiber F-P cavity 1. The inner wall of the F-P cavity is smooth, has excellent anti-interference ability, and has good repeatability and stability.

[0058] 2. The temperature test method of the present application improves the precision and linearity of the optical fiber F-P cavity 1 by collecting data and optimizing algorithm analysis.

[0059] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered within the protection scope of the present application.

Claims

1. A temperature testing method, characterized by, The temperature testing system comprises a heating platform, a fiber modem, a processor and a fiber temperature sensor; The fiber temperature sensor has a fiber F-P cavity, which is a concave cavity etched on a single-mode optical fiber. The heating platform is used to heat the fiber F-P cavity. The fiber modem is optoelectronically connected to the fiber F-P cavity through a single-mode optical fiber. The fiber modem is connected to the processor. The temperature testing method comprises the following steps: Step 1: Measure the length L, depth H and end face inclination angle of the fiber F-P cavity. Step 2: Heat the fiber F-P cavity through the heating platform. Step 3: Connect the fiber F-P cavity to the fiber modem through a fiber adapter. Step 4: Measure the reflected interference light power by using the fiber modem, and collect data, optimize algorithms and save them by using the processor. Step 5: As the temperature rises, the interference spectrum shifts to the long-wave direction. By determining the actual relationship between the spectrum shift and the temperature change, and converting it into a linear relationship between the temperature and the wavelength shift, a fiber F-P cavity temperature sensor is formed.

Images