An interferometer sensing array based on photonic crystal fiber and its preparation method

Abstract

The present application belongs to the field of sensor technology, and specifically relates to an interferometer sensor array based on photonic crystal fiber and its preparation method. The interferometer sensor array based on photonic crystal fiber is formed by cascading multiple photonic crystal fiber interferometers with different collapse lengths. Each of the photonic crystal fiber interferometers includes: a first single-mode fiber, a photonic crystal fiber, and a second single-mode fiber; the first single-mode fiber is fused with one end of the photonic crystal fiber to form a first collapse region, and the other end of the photonic crystal fiber is fused with the second single-mode fiber to form a second collapse region; wherein the sum of the collapse lengths of the first collapse region and the second collapse region is the collapse length of the photonic crystal fiber interferometer. The interferometer sensor array realizes precise measurement of strain, and cascading the photonic crystal fiber interferometers can simultaneously realize real-time monitoring of multiple sets of parameters.

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 convert mechanical deformation into optical and electrical signals, playing a vital role in fields such as robotics, human-machine interaction, electronic skin, human health, aircraft structures, and ground deformation monitoring. Fiber optic sensors offer numerous advantages, including immunity to electromagnetic interference, corrosion resistance, miniaturization, fast response, remote operation, and real-time monitoring. They are a unique or even exclusive sensing method in specific situations, such as those involving electrical hazards or explosive environments. These advantages hold great promise and promise for their application in strain sensing.

[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. Traditional optical fiber cores are doped with other materials, and their thermal sensitivity coefficient is much higher than that of pure silica.

[0004] Currently, there are numerous reports on strain sensors based on photonic crystal fibers. These sensors primarily include Fabry-Perot interferometers, Mach-Zehnder interferometers, Sacgnac interferometers, long-period gratings, and mode coupling. These sensors are used as single-point sensors, providing wavelength encoding and high-resolution measurements. Connecting multiple sensors in series to form a sensor array and utilizing a single interrogation unit to simultaneously measure multiple sensing points can significantly reduce sensor cost and complexity and enable the formation of sensor networks. Summary of the Invention

[0005] In view of this, the purpose of this 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 accurate measurement of strain. Cascading the photonic crystal fiber interferometer can simultaneously realize real-time monitoring of multiple groups of parameters.

[0006] The present application provides an interferometer sensing array based on photonic crystal fiber, which is formed by connecting multiple photonic crystal fiber interferometers with different collapse lengths in series, each of which includes:

[0007] a first single-mode optical fiber, a photonic crystal optical fiber, and a second single-mode optical fiber;

[0008] 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.

[0009] 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 sensing array.

[0010] Furthermore, the collapsed length of the photonic crystal fiber interferometer ranges from 450 to 900 μm to improve the contrast of the output fringes.

[0011] 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.

[0012] The present application also provides a method for preparing an interferometer sensor array based on photonic crystal fiber, the preparation method comprising:

[0013] Remove the coating of the photonic crystal fiber and the single-mode fiber, wipe them with alcohol, and then place the photonic crystal fiber and the single-mode fiber at both ends of the fusion splicer and align them manually.

[0014] By setting different splicing parameters, the photonic crystal fiber and the single-mode fiber are fused to obtain a photonic crystal fiber interferometer with different collapse lengths; wherein the splicing parameters include discharge intensity, discharge time, offset, and thrust;

[0015] Multiple photonic crystal fiber interferometers with different collapse lengths are cascaded to obtain an interferometer sensing array.

[0016] Furthermore, the photonic crystal fiber and the single-mode fiber are fused together by the following method:

[0017] Setting the first splicing parameters and performing the first splicing on the photonic crystal fiber and the single-mode fiber to control the length of the collapsed region within the range of 140±20µm;

[0018] Setting the second fusion splicing parameters and performing multiple discharges on the photonic crystal fiber and the single-mode fiber to precisely control the length of the collapsed region;

[0019] The single-mode optical fiber includes: a first single-mode optical fiber and a second single-mode optical fiber.

[0020] Furthermore, the second welding parameter has a control accuracy of 60±20µm on the length of the collapsed area.

[0021] 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 interferometers can simultaneously realize real-time monitoring of multiple groups of parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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;

[0023] Figure 2 The figure shows the transmission spectra of the interferometer under different first collapsed region lengths provided by the embodiment of the present application;

[0024] Figure 3 The figure shows the transmission spectra of the interferometer under different second collapsed region lengths provided by the embodiment of the present application;

[0025] Figure 4 The transmission spectra of the interferometer in forward and reverse connection under different collapsed region lengths provided by the embodiment of the present application are shown;

[0026] Figure 5 The schematic diagram of the interferometer sensor array based on photonic crystal fiber provided in an embodiment of the present application is shown;

[0027] Figure 6 The output spectrum of the interferometer under different strain conditions provided by the embodiment of the present application is shown;

[0028] Figure 7 The relationship between the trough position and strain corresponding to the interferometer provided in the embodiment of the present application is shown;

[0029] Figure 8 The total output spectrum of the three interferometers provided in the embodiment of the present application after cascading is shown;

[0030] Figure 9 The figure shows the strain experiment results of the interferometer with a photonic crystal fiber length of 10.5 mm provided in an embodiment of the present application;

[0031] Figure 10 An enlarged view of the interference trough of the 10.5 mm interferometer provided in an embodiment of the present application is shown;

[0032] Figure 11The relationship between the trough movement and strain of three interferometers provided in the embodiments of the present application is shown;

[0033] Figure 12 A diagram showing the relationship between the movement of three interferometer troughs and strain during the recovery process provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of this technical solution more clear, the following technical solution is further described in detail 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 this technical solution.

[0035] Example 1: Introduction to the preparation method and working principle of the interferometer based on photonic crystal fiber:

[0036] See also Figure 1 , Figure 1 Figure 1 shows a cross-sectional view of a photonic crystal fiber and a schematic diagram of the interferometer structure provided by 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 the first collapsed region; and CR2 represents the second collapsed region.

[0037] like Figure 1 The cross-section of the photonic crystal fiber shown above shows that the photonic crystal fiber consists of six layers of air holes arranged in a hexagonal pattern. 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, its more complex cladding structure can excite more high-order modes, which allows the interferometer to have a richer output spectrum.

[0038] Based on the photonic crystal fiber structure above, an interferometer is prepared by the following method:

[0039] 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 splicing program for this model of photonic crystal fiber in the fusion splicer, the fusion splicing of the single-mode fiber and the photonic crystal fiber in the embodiment of the present application is completed by manual fusion splicing.

[0040] The preparation of the interferometer in the embodiment of the present application involves only simple cutting and welding, which can be completed using 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 discharged at an appropriate discharge intensity. The porous structure of the photonic crystal fiber collapses completely under the stimulation of high-intensity current, forming a solid silicide, which is the collapsed area.

[0041] like Figure 1 The schematic diagram of the interferometer structure shown at the bottom shows that light is introduced from the single-mode fiber at the left end and then enters the solid silicide. The light is diffracted and broadened within the silicide, and then enters the core and cladding of the photonic crystal fiber. It meets and couples in the collapsed region at the other end of the photonic crystal fiber, forming Mach-Zehnder interference.

[0042] Example 2: Analyze the relationship between the output spectrum of the interferometer and the length of the collapsed region:

[0043] See also Figure 2 and Figure 3 , Figure 2 FIG. 1 shows the transmission spectrum of the interferometer under 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.

[0044] 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 kept constant at 607 μm. The length of the first collapsed region is continuously increased. Interferometers with different first collapsed region lengths are obtained, and the corresponding transmission spectra are recorded as follows: Figure 2 shown.

[0045] Figure 2 The dotted lines are used to define two wavelength ranges to track the movement trend of the trough. The left dotted line is used to define the range to analyze the movement trend of trough 1, which corresponds to Figure 2 In the interval marked as 1, the moving trend of trough 2 is analyzed by limiting the range with the dotted line on the right, 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 redshifts, the depth of trough 1 does not change significantly, while the depth of trough 2 becomes significantly smaller.

[0046] 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 kept constant at 106 μm, and the length of the second collapsed region is continuously increased. Interferometers with different second collapsed region lengths are obtained, and the corresponding transmission spectra are recorded as follows: Figure 3 shown.

[0047] 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 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.

[0048] 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 sensing 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.

[0049] Example 3: Analysis of the influence of the forward and reverse connection of the interferometer on the transmission spectrum:

[0050] See also Figure 4 , Figure 4 Shown are transmission spectra of the interferometer in forward and reverse connection under different collapsed region lengths provided in the embodiments of the present application.

[0051] The length of the photonic crystal fiber is 10 mm, and an interferometer with different lengths of the first collapsed region and the second collapsed region is prepared. The corresponding transmission spectra of the interferometer under different lengths of the collapsed region 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 three groups of interferometers with different collapsed area lengths.

[0052] 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, and there will be a certain loss in this process.

[0053] Furthermore, by performing a fast Fourier transform on the spectrum, it was found that the component frequencies of the interferometer connected forwards and reversely were almost the same, which means that the output spectra of the interferometer connected forwards and reversely 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.

[0054] Example 4: Determination of Collapse Region Length and Photonic Crystal Fiber Length of Photonic Crystal Fiber Interferometer

[0055] In the present embodiment, multiple sets of interferometers with different photonic crystal fiber lengths and different collapsed region lengths were prepared. By summarizing the output spectra of the interferometers made with 3-30 mm photonic crystal fibers, it was concluded that when the sum of the collapsed region lengths is in the range of 450-900 µm, the interferometer can output a spectrum with a larger fringe contrast.

[0056] and Figure 2 and 3 It shows 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.

[0057] 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 there are certain uncontrollable factors in the preparation of the collapsed area, 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.

[0058] 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 of

[0059] Where, λ is the central wavelength of the light source, Δ n eff = , which is the difference between the effective refractive indices of the guided modes in the core and cladding, L is the length of the sensing area.

[0060] When the refractive index difference between the fiber core and cladding is constant, Δ n eff is a constant and is easy to obtain FSR Only LIt is inversely proportional to the wavelength of the optical 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.

[0061] For the embodiment of the present application, in order to minimize crosstalk between interferometers and to enable 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.

[0062] Example 5: Preparation method of interferometer sensor array based on photonic crystal fiber:

[0063] Based on the conclusions drawn from the above analysis, an interferometer sensor array based on photonic crystal fiber was finally prepared. Specifically:

[0064] In a fiber fusion splicer, after aligning a photonic crystal fiber and a single-mode fiber, the length of the collapsed region is varied by adjusting the splicing parameters. Setting these parameters directly impacts the splicing quality, and for specialty fibers like photonic crystal fibers, extensive experimentation is required to determine the appropriate parameters. Splicing parameters primarily include discharge intensity, discharge time, offset, and thrust. Discharge intensity and discharge time are the most important parameters, directly impacting splice quality. Longer discharge intensity and discharge time result in a stronger splice.

[0065] The LMA-10 PCF used in the embodiments of this application has a six-layer air hole structure. The porous structure causes its melting point to be lower than that of ordinary optical fibers. To collapse the air holes while keeping 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 must be close to the discharge of the single-mode fiber. Therefore, it is necessary to select a suitable offset to better achieve the desired effect. The propulsion amount refers to the distance the motor responsible for propulsing the optical fibers at both ends advances 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. The appropriate propulsion amount can not only make the fusion point complete, but also increase the strength of the fusion point. Too little propulsion amount will cause bubbles to appear at the fusion point, or even make the two optical fibers unable to be fused at all. Too much propulsion amount will cause the optical fiber fusion point to overlap excessively, resulting in bulges and increased losses.

[0066] After a large number of experiments, the appropriate welding parameters were finally obtained as shown in Table 1 below. The first row of Table 1 shows 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 collapse area.

[0067] Table 1. Relationship between collapse length and welding parameters

[0068] Collapse length Discharge intensity Discharge time Right z-axis advancement 140±20μm 50J / s 650s 15μm 60±20um 40J / s 600s 0μm

[0069] Furthermore, an interferometer sensing array is obtained by cascading multiple photonic crystal fiber interferometers.

[0070] Example 6: Feasibility Verification of Interferometer Sensing Array Based on Photonic Crystal Fiber:

[0071] See also Figure 5 , Figure 5 The figure shows the principle diagram of the interferometer sensor array based on photonic crystal fiber provided by the embodiment of the present application. N They represent the trough positions corresponding to a single photonic crystal fiber interferometer.

[0072] First, the feasibility of a single interferometer was experimentally verified. The interferometer length 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 microstrain to be generated in the photonic crystal fiber interferometer. Each time, 200 units of microstrain were applied. Figure 6 The output spectra of the interferometer under different strain conditions are shown. To make the spectral shift more clear, only the spectrum in the 1630-1640nm wavelength range is shown in the figure. As the strain increases, the spectrum shifts to shorter wavelengths. In fact, there is only one trough in the 1575-1680nm wavelength range, and only the spectrum near the trough has a large range of blue shift, while the spectrum in other parts hardly changes. This also provides the feasibility of cascading photonic crystal fiber interferometers and then realizing sensor arrays.

[0073] Applying micro strain to the photonic crystal fiber interferometer compresses the air hole of the photonic crystal fiber and lengthens it, causing the refractive index of the fiber core and cladding mode to change. At the same time, the optical path of light in the sensor is lengthened, which ultimately 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.

[0074] Secondly, three photonic crystal fiber interferometers with easily distinguishable troughs were prepared, and the photonic crystal fiber interferometers were connected in series to form a strain sensor array. The lengths of the interferometers were 9.5mm, 10.5mm, and 11.9mm, respectively. The lengths of the first collapsed region were 171µm, 274µm, and 229µm, respectively. The lengths of the second collapsed region were 300µm, 177µm, and 267µm, respectively. The trough positions were 1558.5nm, 1585.1nm, and 1614.4nm, respectively. 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 individual interferometers, 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.

[0075] Furthermore, strain experiments were conducted on the cascaded interferometers. A total strain of 1800 με and a strain interval of 100 με were applied to the interferometer with a photonic crystal fiber length of 10.5 mm, while no stress was applied to the other two interferometers. The following results were obtained: Figure 9 The graph shown is a graph of strain experiment results of an interferometer with a photonic crystal fiber length of 10.5 mm provided in an embodiment of the present application. Figure 9 The trough corresponding to the 10.5mm interferometer is in the 1570-1600nm band. As the strain increases, the interference trough moves toward the shorter wavelength, while the troughs corresponding to the other two interferometers basically do not move. This shows that the movement of the spectrum caused by detection using this interferometer will not affect the detection of the other two interferometers.

[0076] Figure 10 The figure shows an enlarged view of the interference trough of the 10.5 mm interferometer provided in an 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. Figure 11 The figure shows the relationship between the trough movement and strain for the three interferometers provided in the embodiments of this application. In the figure, black indicates the trough position of the 9.5mm interferometer, red indicates the trough position of the 10.5mm interferometer, and blue indicates the trough position of the 11.5mm interferometer. A linear fit was performed on the trough corresponding to the 10.5mm interferometer, and the linear fit coefficient reached 0.999. The fitting equation is y = -0.00144 x + 0.05005, with a sensitivity of -1.44 pm / με. The maximum movement of the other two troughs is 0.042 nm.

[0077] From the measurement and linear fitting results, we can see that 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 three-dimensional displacement platform to its initial state, and obtained the following: Figure 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 graphs 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.

[0078] Photonic crystal fiber interferometers, developed based on photonic crystal fibers, feature low temperature crosstalk and flexible operation. The constructed photonic crystal fiber interferometer sensor array achieves precise strain measurement. By coating or filling photonic crystal fibers with functional materials, detection in various fields, such as medical diagnosis, drug development, and biomolecular recognition, can be further implemented. Cascading photonic crystal fiber interferometers enables simultaneous real-time monitoring of multiple parameters. With the continuous development of new materials and fiber optic sensing technology, the application prospects of photonic crystal fiber sensor arrays are expected to expand.

[0079] The above content is only a preferred embodiment of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scope 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 multiple photonic crystal fiber interferometers with different collapse lengths, each of which includes: 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; 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 sensing array; The collapsed length of the photonic crystal fiber interferometer ranges from 450 to 900 µm to improve the contrast of the output fringes. The length of the photonic crystal fiber is 10 ± 0.5 mm to reduce the length of the sensing area and increase the free spectral range, thereby improving the discrimination of each photonic crystal fiber interferometer. The contrast of the output fringes is characterized by deeper troughs.

2. The interferometer sensor array based on photonic crystal fiber according to claim 1, characterized in that: Prepared by the following method: Remove the coating of the photonic crystal fiber and the single-mode fiber, wipe them with alcohol, and then place the photonic crystal fiber and the single-mode fiber at both ends of the fusion splicer and align them manually. By setting different splicing parameters, the photonic crystal fiber and the single-mode fiber are fused to obtain a photonic crystal fiber interferometer with different collapse lengths; wherein the splicing parameters include discharge intensity, discharge time, offset, and thrust; Multiple photonic crystal fiber interferometers with different collapse lengths are cascaded to obtain an interferometer sensing array.

3. The interferometer sensor array based on photonic crystal fiber according to claim 2, characterized in that: The photonic crystal fiber and single-mode fiber are fused together using the following method: Setting the first splicing parameters and performing the first splicing on the photonic crystal fiber and the single-mode fiber to control the length of the collapsed region within the range of 140±20µm; Setting the second fusion splicing parameters and performing multiple discharges on the photonic crystal fiber and the single-mode fiber 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.

4. The interferometer sensor array based on photonic crystal fiber according to claim 3, characterized in that: The second welding parameter controls the length of the collapsed area with an accuracy of 60±20µm.

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