Interferometer sensing array based on photonic crystal fiber and preparation method thereof

Abstract

The invention belongs to the technical field of sensors, and particularly relates to an interferometer sensing array based on a photonic crystal fiber and a preparation method of the interferometer sensing array. The interferometer sensor array based on the photonic crystal fiber is formed by cascading a plurality of photonic crystal fiber interferometers with different collapse lengths, and each photonic crystal fiber interferometer comprises a first single-mode fiber, a photonic crystal fiber and a second single-mode fiber; the first single-mode fiber is welded with one end of the photonic crystal fiber to form a first collapse area, and the other end of the photonic crystal fiber is welded with the second single-mode fiber to form a second collapse area; wherein the sum of the collapse length of the first collapse area and the collapse length of the second collapse area is the collapse length of the photonic crystal fiber interferometer. The interferometer sensing array realizes accurate measurement of strain, and the photonic crystal fiber interferometers are cascaded, so that multiple groups of parameters can be monitored in real time at the same time.

Description

Technical Field

[0001] The present application belongs to the field of sensor technology, and in particular relates to an interferometer sensor array based on photonic crystal fiber and a preparation method thereof. Background Art

[0002] Strain sensors can convert mechanical deformation into optical and electrical signals, and play an important role in the fields of robotics, human-machine interaction, electronic skin, human health, aircraft structure, and ground deformation monitoring. Fiber optic sensors have many outstanding advantages such as anti-electromagnetic interference, corrosion resistance, miniaturization, fast response speed, remote operation, and real-time monitoring. In certain situations (such as electrical hazards or explosive environments), they are a unique or only sensing method. Based on the above advantages, fiber optic sensors have good prospects and great application value in the field of strain detection.

[0003] Among them, photonic crystal fiber has characteristics that traditional optical fibers do not have: 1) Traditional optical fibers are usually all-solid materials, while photonic crystal fibers contain many air holes, which makes them more easily deformed when subjected to mechanical forces. Therefore, strain sensors based on photonic crystal fibers have higher sensitivity; 2) The background material of photonic crystal fibers is only pure silica and air holes, and its thermal dependence is very low, so the crosstalk between strain and temperature can be avoided. Since the core of traditional optical fibers is doped with other materials, its thermal sensitivity coefficient is much higher than that of pure silica.

[0004] At present, there have been many reports on strain sensors based on photonic crystal fibers. The main sensing types include Fabry-Perot interferometer, Mach-Zehnder interferometer, Sachnac interferometer, long period grating, mode coupling, etc. They are all used as single point sensors to provide wavelength encoding and high-resolution measurement. Connecting multiple sensors in series to realize a sensor array and using a single interrogation unit to realize simultaneous measurement of multiple sensing points can greatly reduce the cost and complexity of the sensor and make the formation of a sensor network possible. Summary of the invention

[0005] In view of this, the purpose of the present application is to provide an interferometer sensor array based on photonic crystal fiber and a preparation method thereof. The photonic crystal fiber interferometer prepared based on photonic crystal fiber has the characteristics of low temperature crosstalk and flexible operation. The constructed photonic crystal fiber interferometer sensor array realizes the precise measurement of strain. Cascading the photonic crystal fiber interferometer can realize real-time monitoring of multiple groups of parameters at the same time.

[0006] The present application provides an interferometer sensor array based on photonic crystal fiber, which is formed by connecting a plurality of photonic crystal fiber interferometers with different collapse lengths in series, each of which comprises: A first single-mode optical fiber, a photonic crystal optical fiber, and a second single-mode optical fiber; The first single-mode optical fiber is fused with one end of the photonic crystal optical fiber to form a first collapsed region, and the other end of the photonic crystal optical fiber is fused with the second single-mode optical fiber to form a second collapsed region; wherein the sum of the collapsed lengths of the first collapsed region and the second collapsed region is the collapsed length of the photonic crystal fiber interferometer.

[0007] Furthermore, by controlling the collapsed length of the photonic crystal fiber interferometer and the length of the photonic crystal fiber, interferometers with different resonance wavelengths are obtained to achieve multi-point measurement of the interferometer sensor array.

[0008] Furthermore, the collapsed length of the photonic crystal fiber interferometer ranges from 450 to 900 µm to improve the contrast of the output fringes.

[0009] Furthermore, the length of the photonic crystal fiber is 10±0.5 mm, so as to reduce the length of the sensing area and increase the free spectrum range, thereby improving the discrimination of each photonic crystal fiber interferometer.

[0010] The present application also provides a method for preparing an interferometer sensor array based on photonic crystal fiber, the preparation method comprising: After removing the coating of the photonic crystal fiber and the single-mode fiber and wiping them with alcohol, the photonic crystal fiber and the single-mode fiber are placed at the two ends of the fusion splicer respectively and manually aligned; By setting different welding parameters, the photonic crystal fiber and the single-mode fiber are welded to obtain a photonic crystal fiber interferometer with different collapse lengths; wherein the welding parameters include: discharge intensity, discharge time, offset and propulsion; Multiple photonic crystal fiber interferometers with different collapse lengths are cascaded to obtain an interferometer sensing array.

[0011] Furthermore, the photonic crystal fiber and the single-mode fiber are fused by the following method: Setting the first fusion splicing parameters, and performing the first fusion splicing on the photonic crystal fiber and the single-mode fiber, so as to control the length of the collapsed region within the range of 140±20µm; The second fusion splicing parameters are set to discharge the photonic crystal fiber and the single-mode fiber multiple times to precisely control the length of the collapsed region; The single-mode optical fiber includes: a first single-mode optical fiber and a second single-mode optical fiber.

[0012] Furthermore, the control accuracy of the second welding parameter on the length of the collapsed area is 60±20µm.

[0013] The present application provides an interferometer sensor array based on photonic crystal fiber and a preparation method thereof. The photonic crystal fiber interferometer prepared based on photonic crystal fiber has the characteristics of low temperature crosstalk and flexible operation. The constructed photonic crystal fiber interferometer sensor array realizes accurate measurement of strain. Cascading the photonic crystal fiber interferometer can realize real-time monitoring of multiple groups of parameters at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A cross-sectional view of a photonic crystal fiber and a schematic diagram of an interferometer structure provided in an embodiment of the present application are shown; Figure 2 The transmission spectrum diagram of the interferometer under different first collapsed region lengths provided by the embodiment of the present application is shown; Figure 3 The transmission spectrum diagram of the interferometer under different second collapsed region lengths provided by the embodiment of the present application is shown; Figure 4 The transmission spectra of the interferometer in forward and reverse connection under different collapsed region lengths provided in the embodiments of the present application are shown; Figure 5 The schematic diagram of the interferometer sensor array based on photonic crystal fiber provided in the embodiment of the present application is shown; Figure 6 The output spectrum diagram of the interferometer under different strain conditions provided by the embodiment of the present application is shown; Figure 7 The relationship between the trough position and strain corresponding to the interferometer provided in the embodiment of the present application is shown; Figure 8 The total output spectrum diagram after the three interferometers provided in the embodiment of the present application are cascaded is shown; Fig. 9 The figure shows the strain test result of the interferometer with a photonic crystal fiber length of 10.5 mm provided in the embodiment of the present application; Fig.10 An enlarged view of the interference trough of the 10.5 mm interferometer provided in an embodiment of the present application is shown; Fig.11 The relationship between the trough movement and strain of three interferometers provided in the embodiments of the present application is shown; Fig.12 A graph showing the relationship between the movement of the three interferometer troughs and the strain during the recovery process provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical solution and advantages of the technical solution more clear, the technical solution is further described in detail below in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the technical solution.

[0016] Embodiment 1: Introduce the preparation method and working principle of the interferometer based on photonic crystal fiber: See also Figure 1 , Figure 1 The figure shows a cross-sectional view of a photonic crystal fiber and a schematic diagram of an interferometer structure provided in an embodiment of the present application. In the figure, SMF-in represents the input end of a single-mode fiber, i.e., the first single-mode fiber, SMF-out represents the output end of a single-mode fiber, i.e., the second single-mode fiber, PCF represents a photonic crystal fiber, CR1 represents a first collapsed region, and CR2 represents a second collapsed region.

[0017] like Figure 1 The cross-sectional view of the photonic crystal fiber shown above shows that the photonic crystal fiber consists of six layers of air holes arranged in a hexagonal shape. Compared with ordinary single-mode photonic crystal fiber, it has more air hole structures. Although it is also a refractive index-guided photonic crystal fiber, the more complex cladding structure can excite more high-order modes, which allows the interferometer to have a richer output spectrum.

[0018] Based on the photonic crystal fiber of the above structure, an interferometer is prepared by the following method: As an example, the embodiment of the present application uses a photonic crystal fiber of model LMA-10 PCF, which has an endless single-mode transmission characteristic, can provide excellent mode quality in all wavelength ranges, and can maintain low transmission loss in the range of 500-1700nm. The model of the fusion splicer used is FITEL s179c. Since there is no fixed fusion program for this model of photonic crystal fiber in the fusion splicer, the fusion of the single-mode fiber and the photonic crystal fiber in the embodiment of the present application is completed by manual fusion splicing.

[0019] The preparation of the interferometer of the embodiment of the present application only involves simple cutting and welding, which can be completed by a cutting knife and a welding machine. Specifically: before welding, the coating layer of the photonic crystal fiber and the single-mode fiber is removed and wiped with alcohol, the photonic crystal fiber and the single-mode fiber are placed at both ends of the welding machine, manually aligned, and the discharge is performed by selecting a suitable discharge intensity. The porous structure of the photonic crystal fiber collapses completely under the stimulation of high-intensity current to form a solid silicide, which is the collapsed area.

[0020] like Figure 1 The schematic diagram of the interferometer structure shown in the lower part, light is introduced from the single-mode optical fiber at the left end, then enters the solid silicide, where it is diffracted and broadened, and then enters the core and cladding of the photonic crystal fiber, where it meets and couples in the collapsed region at the other end of the photonic crystal fiber, forming Mach-Zehnder interference.

[0021] Embodiment 2: Analyze the relationship between the output spectrum of the interferometer and the length of the collapsed region: See also Figure 2 and Figure 3 , Figure 2 FIG. 1 is a transmission spectrum diagram of the interferometer at different first collapsed region lengths provided in the embodiment of the present application. Figure 3 Shown is a transmission spectrum diagram of the interferometer at different second collapsed region lengths provided in an embodiment of the present application.

[0022] 1) The length of the photonic crystal fiber is set to 5 mm. At the same time, the length of the second collapsed region of the interferometer is controlled to remain unchanged at 607 µm, and the length of the first collapsed region is continuously increased. Interferometers with different lengths of the first collapsed region are obtained, and the corresponding transmission spectra are recorded as follows: Figure 2 shown.

[0023] Figure 2 The dashed lines are used to define two wavelength ranges to track the movement trend of the trough. The left dashed line is used to define the range to analyze the movement trend of trough 1, which corresponds to Figure 2 The interval marked as 1 in the figure uses the dotted line on the right to limit the range and analyze the moving trend of trough 2, which corresponds to Figure 2 The interval marked as 2 in Figure 2 It can be seen that when the length of the second collapsed area remains unchanged, as the length of the first collapsed area continues to increase, the transmission spectrum red shifts, the depth of trough 1 does not change significantly, and the depth of trough 2 becomes significantly smaller.

[0024] 2) The length of the photonic crystal fiber is set to 5 mm. At the same time, the length of the first collapsed region of the interferometer is controlled to remain unchanged at 106 µm, and the length of the second collapsed region is continuously increased. Interferometers with different lengths of the second collapsed region are obtained, and the corresponding transmission spectra are recorded as follows: Figure 3 shown.

[0025] Figure 3 Use with Figure 2 In the same way, two wavelength ranges are defined, namely Figure 3 The interval marked as 1 is used to analyze the moving trend of trough 1. Figure 3 The interval marked as 2 in the figure is used to analyze the moving trend of trough 2. Figure 3 It can be seen that when the length of the first collapsed area remains unchanged, as the length of the second collapsed area continues to increase, the transmission spectrum red-shifts and the trough contrast changes significantly, that is, as the length of the second collapsed area increases, the depth of trough 1 increases, while the depth of trough 2 first increases and then decreases.

[0026] In addition, based on photonic crystal fibers with lengths of 3mm, 10mm, 20mm, and 30mm, the relationship between the length of the collapsed area and the fringe contrast was recorded, and it was finally concluded that the position and depth of the trough are closely related to the length of the collapsed area. Deeper troughs improve the contrast and are more conducive to sensor detection. By tuning the position of the trough, a fiber optic sensor array can be realized, that is, each interferometer can produce a narrow and deep trough as long as the length of the collapsed area is properly controlled.

[0027] Example 3: Analysis of the influence of the forward and reverse connection of the interferometer on the transmission spectrum: See also Figure 4 , Figure 4 Shown are transmission spectra of the interferometer in forward and reverse connection at different collapsed region lengths provided in the embodiments of the present application.

[0028] The length of the photonic crystal fiber is 10 mm, and interferometers with different lengths of the first collapsed region and the second collapsed region are prepared, and the transmission spectra corresponding to the forward and reverse connections of the interferometers with different collapsed region lengths are recorded. As an example, Figure 4 In the figure, 171-300 represents the interferometer forward connection, and 300-171 represents the interferometer reverse connection. This application prepares 3 groups of interferometers with different collapsed area lengths.

[0029] Depend on Figure 4 It can be seen that the spectral morphology of the same interferometer is basically the same, but there is a certain difference in the intensity of the output light. Generally, the light intensity of the reverse-connected interferometer is weaker. This is caused by the flange. The flange originally connected to the output optical fiber needs to be connected to a jumper wire to the light source input port. There will be a certain loss in this process.

[0030] Furthermore, by performing a fast Fourier transform on the spectrum, it was found that the component frequencies of the interferometer connected forward and reverse were almost the same, which means that the output spectra of the interferometer connected forward and reverse were the same. Therefore, it was concluded that the shape of the spectrum is related to the sum of the lengths of the collapsed areas.

[0031] Example 4: Determination of Collapse Region Length and Photonic Crystal Fiber Length of Photonic Crystal Fiber Interferometer In the embodiment of the present application, multiple groups of interferometers with different photonic crystal fiber lengths and different collapsed area lengths are prepared. By summarizing the output spectra of the interferometers made with 3-30 mm photonic crystal fibers, it is concluded that when the sum of the collapsed area lengths is in the range of 450-900 µm, the interferometer can output a spectrum with a larger fringe contrast.

[0032] and Figure 2 and 3It is shown that as the length of the collapsed area increases, the overall light transmittance of the interferometer will decrease to a certain extent. The maximum number of sensors that can be reused in the sensor array depends on the optical power loss of the passive devices in the sensor array, the optical power loss of the sensors, and the minimum optical power value that the detector can detect. Therefore, reducing the optical power loss of the interferometer itself can greatly increase the multiplexing capability of the sensor array.

[0033] To sum up, the selection of the length of the collapsed area should be based on the premise of being able to excite narrow and deep troughs. Since the preparation of the collapsed area has certain uncontrollable factors, the sum of the lengths of the collapsed areas of the interferometer prepared in the embodiment of the present application is about 500µm. If the collapsed area on one side is too short, the welding point will be weak and easy to cause damage. If the collapsed area on one side is too long, it will be affected by external crosstalk.

[0034] In order to facilitate cascading, the free spectral range of the spectrum is increased by preparing an interferometer with a shorter sensing area so that it is easier to distinguish during cascading. FSR The definition is In the formula, λ is the central wavelength of the light source, Δ n eff = , which is the difference in effective refractive index between the core and cladding guided modes, L is the length of the sensing area.

[0035] When the refractive index difference between the fiber core and cladding is constant, Δ n eff is a constant and can be easily obtained FSR Only L It is inversely proportional to the length of the photonic crystal fiber, so it is concluded that the free spectral range of the interferometer can be controlled by controlling the length of the photonic crystal fiber.

[0036] For the embodiment of the present application, in order to minimize the crosstalk between interferometers and to achieve multiplexing of multiple interferometers in a shorter wavelength range, a photonic crystal fiber with a length of about 10 mm, specifically 10±0.5 mm, is selected to prepare the interferometer.

[0037] Embodiment 5, preparation method of interferometer sensor array based on photonic crystal fiber: Based on the conclusions drawn from the above analysis, an interferometer sensor array based on photonic crystal fiber was finally prepared. Specifically: In the fiber fusion splicer, after aligning the photonic crystal fiber and the single-mode fiber, the length of the collapsed area is changed by changing the fusion parameters. The setting of the fusion parameters directly affects the fusion effect, especially for special optical fibers such as photonic crystal fibers, a lot of experiments are needed to obtain the appropriate parameters. The fusion parameters mainly include the following aspects: discharge intensity, discharge time, offset and propulsion. Among them, the discharge intensity and discharge time are the most important parameters, which directly affect the quality of the fusion. The longer the discharge intensity and discharge time, the stronger the intensity at the fusion point.

[0038] The LMA-10 PCF used in the embodiment of the present application has a six-layer air hole structure. The porous structure causes its melting point to be lower than that of general optical fibers. To collapse the air holes and keep the optical fiber structure intact requires a longer discharge time and a lower discharge intensity. In order to slow down the collapse speed of the air holes in the photonic crystal fiber and better control the length of the collapsed area, the discharge area should be close to the single-mode optical fiber discharge, so it is necessary to select a suitable offset to better achieve the desired effect. The propulsion amount is the distance that the motor responsible for propulsing the optical fibers at both ends propels when the optical fiber is in a molten state after the fusion splicer discharges. The propulsion amount has a great influence on the shape of the fusion point, and the appropriate propulsion amount can not only make the fusion point complete, but also increase the strength of the fusion point. Too small a propulsion amount will cause bubbles to appear at the fusion point, and even the two sections of optical fiber cannot be fused at all, while too large a propulsion amount will cause the optical fiber fusion point to overlap excessively, resulting in bulges and increased losses.

[0039] Through a large number of experiments, the appropriate welding parameters are finally obtained as shown in Table 1. The first row of Table 1 is the first welding parameters, that is, the length of the photonic crystal fiber welding collapse area is first controlled between 140±20µm, and then multiple discharges are performed through the second welding parameters in the second row, so as to achieve precise control of the length of the collapsed area.

[0040] Table 1. Relationship between collapse length and welding parameters Collapse length Discharge intensity Discharge time Right z-axis advancement 140±20μm 50J / s 650s 15μm 60±20um 40J / s 600s 0μm Furthermore, an interferometer sensor array is obtained by cascading multiple photonic crystal fiber interferometers.

[0041] Example 6: Feasibility verification of interferometer sensor array based on photonic crystal fiber: See also Figure 5 , Figure 5 The figure shows the principle diagram of the interferometer sensor array based on photonic crystal fiber provided in the embodiment of the present application. N They respectively represent the trough positions corresponding to a single photonic crystal fiber interferometer.

[0042] First, the feasibility of a single interferometer was experimentally verified. The length of the interferometer was selected to be 10 mm, and the photonic crystal fiber interferometer was placed between two three-dimensional displacement platforms. By rotating the horizontal knob of the three-dimensional displacement platform, a horizontal tension was applied to the photonic crystal fiber interferometer, causing micro-strain to be generated in the photonic crystal fiber interferometer, and 200 units of micro-strain were applied each time. Figure 6 The output spectrum of the interferometer under different strain conditions is shown in the figure. In order to see the spectrum shift more clearly, only the spectrum in the wavelength range of 1630-1640nm is shown in the figure. As the strain increases, the spectrum shifts to a shorter wavelength. In fact, there is only one trough in the wavelength range of 1575-1680nm, and only the spectrum near the trough has a large range of blue shift, while the spectrum in other parts has almost no change. This also provides feasibility for cascading photonic crystal fiber interferometers and then realizing sensor arrays.

[0043] Applying micro strain to the photonic crystal fiber interferometer compresses the air holes of the photonic crystal fiber and lengthens them, causing the refractive index of the fiber core and cladding mode to change. At the same time, the optical path of the light in the sensor is lengthened, which eventually causes the spectrum to blue shift. Figure 7 The relationship between the trough position and strain of the interferometer provided in the embodiment of the present application is shown. In the figure, the linear fitting equation is y = -0.00132 x + 1637.632, linearity up to 0.998, sensitivity 1.32pm / με.

[0044] Secondly, three photonic crystal fiber interferometers with easily distinguishable troughs were prepared, and the photonic crystal fiber interferometers were connected in series to obtain a strain sensor array. The lengths of the interferometers were 9.5mm, 10.5mm, and 11.9mm, respectively. The lengths of the first collapsed regions were 171µm, 274µm, and 229µm, respectively. The lengths of the second collapsed regions were 300µm, 177µm, and 267µm, respectively. The trough positions were 1558.5nm, 1585.1nm, and 1614.4nm, respectively. Here, please refer to Figure 8 The total output spectrum of the three interferometers after cascading is shown. In the figure, the interferometers with lengths of 9.5mm, 10.5mm and 11.9mm correspond to trough positions 1, 2 and 3 respectively. The total output spectrum after cascading is the superposition of the output spectra of a single interferometer, and the position of the resonant wavelength remains basically unchanged. It can be clearly seen from the figure that the troughs of the three photonic crystal fiber interferometers are effectively separated and spaced far apart, which means that sufficient spectral movement range is left, which provides a basis for the sensor to measure multiple groups of parameters or multiple points simultaneously.

[0045] Furthermore, the strain experiment was carried out on the cascaded interferometers. The total strain of 1800με and the strain interval of 100με were applied to the interferometer with a photonic crystal fiber length of 10.5mm, and no stress was applied to the other two interferometers. The following results were obtained: Fig. 9 The graph shown is a graph of strain test results of an interferometer with a photonic crystal fiber length of 10.5 mm provided in an embodiment of the present application. Fig. 9 It shows that the trough corresponding to the 10.5mm interferometer is in the 1570-1600nm band. As the strain increases, the interference trough moves to the shorter wavelength, while the troughs corresponding to the other two interferometers basically do not move, indicating that the movement of the spectrum caused by detection using this interferometer will not affect the detection of the other two interferometers.

[0046] Fig.10 The figure shows an enlarged view of the interference trough of the 10.5 mm interferometer provided in the embodiment of the present application. It can be seen that as the strain increases, the transmission first decreases and then remains basically unchanged, and the total wavelength movement is 2.5693 nm. Fig.11 The figure shows the relationship between the displacement of the trough of the three interferometers and the strain provided in the embodiment of the present application. In the figure, black represents the trough position of the 9.5mm interferometer, red represents the trough position of the 10.5mm interferometer, and blue represents the trough position of the 11.5mm interferometer. At the same time, a linear fit was made for the trough corresponding to the 10.5mm interferometer, and the linear fit coefficient reached 0.999. The fitting equation was y = -0.00144 x + 0.05005, and the sensitivity was -1.44pm / με. The maximum displacement of the other two troughs was 0.042nm.

[0047] From the measurement and linear fitting results, cascading the interferometers does not affect their own performance and measurement accuracy. To verify the reversibility of the experiment, we then reduced the strain from 1800με to 0με by returning the horizontal knob of the 3D displacement platform to its initial state, and obtained the following: Fig.12 The relationship between the movement of the three interferometer troughs and the strain during the recovery process provided by the embodiment of the present application is shown. Similarly, black, red and blue are used to represent the trough positions of different interferometers. When conducting the reversibility experiment, we recorded the wavelengths of the three troughs and made a linear fit to the trough corresponding to the 10.5mm interferometer. The fitting equation is y = -0.00145 x + 2.69285, the sensitivity is -1.45pm / με, the linearity is 0.99633, and the maximum movement of the spectrum of the interferometer that was not tested is 0.042nm. By comparing the spectra and linear fitting diagrams of the microstrain experiment and the reversibility experiment, it can be seen that the independence between the sensors is good, and accurate and repeatable measurement of microstrain can be achieved.

[0048] The photonic crystal fiber interferometer developed based on photonic crystal fiber has the characteristics of low temperature crosstalk and flexible operation. The constructed photonic crystal fiber interferometer sensor array realizes the accurate measurement of strain. By coating or filling the photonic crystal fiber with functional materials, it can further realize the detection of multiple fields such as medical diagnosis, drug development, and biomolecule recognition. The cascading of photonic crystal fiber interferometers can realize the real-time monitoring of multiple sets of parameters at the same time. With the continuous development of new materials and optical fiber sensing technology, it is believed that the application prospects of photonic crystal fiber sensor arrays will be broader.

[0049] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present technical content. As long as these changes do not deviate from the concept of the present invention, they all fall within the scope of protection of this patent.

Claims

1. An interferometer sensor array based on photonic crystal fiber, characterized in that: It is formed by cascading a plurality of photonic crystal fiber interferometers with different collapse lengths, each of which comprises: A first single-mode optical fiber, a photonic crystal optical fiber, and a second single-mode optical fiber; The first single-mode optical fiber is fused with one end of the photonic crystal optical fiber to form a first collapsed region, and the other end of the photonic crystal optical fiber is fused with the second single-mode optical fiber to form a second collapsed region; wherein the sum of the collapsed lengths of the first collapsed region and the second collapsed region is the collapsed length of the photonic crystal fiber interferometer.

2. The interferometer sensor array according to claim 1, characterized in that: By controlling the collapsed length of the photonic crystal fiber interferometer and the length of the photonic crystal fiber, interferometers with different resonance wavelengths are obtained to achieve multi-point measurement of the interferometer sensor array.

3. The interferometer sensor array according to claim 2, characterized in that: The collapsed length of the photonic crystal fiber interferometer ranges from 450 to 900 μm to improve the contrast of the output fringes.

4. The interferometer sensor array according to claim 2, characterized in that: The length of the photonic crystal fiber is 10±0.5 mm, so as to reduce the length of the sensing area and increase the free spectrum range, thereby improving the discrimination of each photonic crystal fiber interferometer.

5. A method for preparing an interferometer sensor array based on photonic crystal fiber, characterized in that: The preparation method comprises: After removing the coating of the photonic crystal fiber and the single-mode fiber and wiping them with alcohol, the photonic crystal fiber and the single-mode fiber are placed at the two ends of the fusion splicer respectively and manually aligned; By setting different welding parameters, the photonic crystal fiber and the single-mode fiber are welded to obtain a photonic crystal fiber interferometer with different collapse lengths; wherein the welding parameters include: discharge intensity, discharge time, offset and propulsion; Multiple photonic crystal fiber interferometers with different collapse lengths are cascaded to obtain an interferometer sensing array.

6. The preparation method according to claim 5, characterized in that: Photonic crystal fiber and single mode fiber are fused together by the following method: Setting the first fusion splicing parameters, and performing the first fusion splicing on the photonic crystal fiber and the single-mode fiber, so as to control the length of the collapsed region within the range of 140±20µm; The second fusion splicing parameters are set to discharge the photonic crystal fiber and the single-mode fiber multiple times to precisely control the length of the collapsed region; The single-mode optical fiber includes: a first single-mode optical fiber and a second single-mode optical fiber.

7. The preparation method according to claim 6, characterized in that: The control accuracy of the second welding parameter on the length of the collapsed area is 60±20µm.

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