CN216385762U - Sensor and sensing experimental device based on resonant reflection waveguide and Mach-Zehnder - Google Patents
Sensor and sensing experimental device based on resonant reflection waveguide and Mach-Zehnder Download PDFInfo
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- CN216385762U CN216385762U CN202122410459.7U CN202122410459U CN216385762U CN 216385762 U CN216385762 U CN 216385762U CN 202122410459 U CN202122410459 U CN 202122410459U CN 216385762 U CN216385762 U CN 216385762U
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Abstract
The utility model discloses a sensor and a sensing experimental device based on resonant reflection waveguide and Mach-Zehnder, wherein the sensor comprises a hollow silicon tube HST, a single mode fiber SMF and a capillary micro-tube, two ends of the hollow silicon tube HST are respectively and symmetrically connected with a section of the single mode fiber SMF to integrally form a sensing loop with a balloon structure, and the other end of the single mode fiber SMF respectively penetrates through the capillary micro-tube. The utility model solves the problems of poor stability of the existing optical fiber displacement sensor and temperature crosstalk in displacement measurement in the precision optical fiber displacement sensor in the prior art.
Description
Technical Field
The utility model relates to a sensor and a sensing experimental device based on a resonant reflection waveguide and Mach-Zehnder, belonging to the technical field of optical fiber sensing.
Background
In recent years, with the rapid development of sensing technology, optical fiber sensors are favored for their excellent characteristics of small size, light weight, high sensitivity, corrosion resistance, electromagnetic interference resistance, and the like, and can be used for detection in severe environments such as high temperature and high pressure, strong electromagnetic field, strong corrosion, and the like. The optical fiber displacement measurement has wide application in the fields of composite material health monitoring, civil engineering structures, micro-mechanical systems, medical application and the like. Most of the displacement sensors reported at present are based on electronic sensing technologies, such as capacitive and magnetoresistive displacement sensors. However, displacement sensors based on electronic sensing technology have low long-term stability, poor durability, and are susceptible to high-intensity electromagnetic interference. In previous reports, the displacement sensor based on the fiber bragg grating has the advantages of electromagnetic interference resistance, corrosion resistance, capability of containing a plurality of measuring points in one optical fiber and the like. At present, a part of displacement sensors of fiber bragg gratings are directly used for displacement measurement after writing Bragg gratings on bare fibers, so that the problems of low sensitivity and easy damage exist in the use, the accurate measurement and long-term stable use of micro displacement are difficult to realize, and the industrial production is difficult to realize due to the complex manufacturing process and high cost. Among displacement sensors based on optical interference, the mach-zehnder interferometer (MZI) has the advantages of compact structure, high sensitivity, wavelength coding detection, high reproducibility and the like, and is an attractive structure. Although MZI has the advantage of high accuracy, temperature cross talk is an important issue for displacement measurement.
Aiming at the defects, the utility model designs the displacement and temperature sensor which has the advantages of low manufacturing temperature crosstalk, simple process, stable performance and low price. For resonant reflective waveguide structures, the resonant transmitted light intensity is sensitive to displacement and insensitive to temperature changes. By demodulating the wavelength shift of the MZI for temperature sensing and the light intensity change of the resonant reflective waveguide for displacement sensing, the problem of cross sensitivity of displacement and temperature is solved. Due to different sensing mechanisms, the utility model can be used for sensing temperature and displacement simultaneously. The cost and the manufacturing difficulty of the sensor are reduced only by adopting Single Mode Fiber (SMF), Hollow Silicon Tube (HST) and simple fusion technology. Therefore, the sensor can be applied to the fields of composite material health monitoring, civil engineering structures, micromechanical systems, medical application and the like.
SUMMERY OF THE UTILITY MODEL
In order to solve the defects of the prior art, the utility model aims to provide a sensor and a sensing experimental device based on a resonant reflection waveguide and a Mach-Zehnder, and solves the problems of poor stability of the existing optical fiber displacement sensor and temperature crosstalk in displacement measurement in the precision optical fiber displacement sensing in the prior art.
In order to achieve the above object, the present invention adopts the following technical solutions:
the sensor based on the resonant reflection waveguide and the Mach-Zehnder comprises a hollow silicon tube HST, a single-mode fiber SMF and a capillary micro-tube, wherein two ends of the hollow silicon tube HST are respectively and symmetrically connected with a section of the single-mode fiber SMF to integrally form a sensing loop with a balloon structure, and the other end of the single-mode fiber SMF penetrates through the capillary micro-tube.
Preferably, the hollow silicon tube HST has an inner diameter of 50 μm, an outer diameter of 125 μm and a length of 1.5 cm.
Preferably, the single mode fiber SMF is a single mode communication fiber.
Preferably, the capillary micro-tube has an inner diameter of 1mm and an outer diameter of 1.5 mm.
Preferably, the maximum bending diameter D of the sensing loop is 1.2 cm.
A sensing experiment device comprises an ultraviolet glue, a glass sheet, a light source BBS, a spectrum analyzer OSA and the sensor, wherein the sensor is fixed on the glass sheet through the ultraviolet glue, and the two ends of the sensor are respectively connected with the light source BBS and the spectrum analyzer OSA.
Preferably, the light source BBS is a wide-spectrum light source.
Preferably, the minimum resolution of the optical spectrum analyzer OSA is 0.05 nm.
The utility model achieves the following beneficial effects:
according to the utility model, the sensor is fixed to be a balloon shape after one HST is welded between two sections of SMFs, so that the sensor with the mixed MZI and resonant reflection waveguide is manufactured. For resonant reflective waveguide structures, the resonant transmitted light intensity is sensitive to displacement and insensitive to temperature changes. By demodulating the wavelength shift of the MZI for temperature sensing and the light intensity change of the resonant reflective waveguide for displacement sensing, the problem of cross sensitivity of displacement and temperature is solved. Due to different sensing mechanisms, the utility model can be used for sensing temperature and displacement simultaneously, and the sensing probe has the advantages of simple structure, stable performance and low price.
Drawings
FIG. 1 is a block diagram of a sensor of the present invention;
fig. 2 is a schematic diagram of the optical path in the bending state hollow silicon tube HST of the present invention;
FIG. 3 is a displacement sensing verification device of the present invention;
fig. 4 is a temperature sensing verification device of the present invention.
The meaning of the reference symbols in the figures: 1-hollow silicon tube HST; 2-single mode fiber SMF; 3-ultraviolet glue; 4-capillary microtubes; 5-a glass sheet; 6-light source BBS; 7-optical spectrum analyzer OSA.
Detailed Description
The utility model is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The embodiment discloses a sensor based on a resonant reflection waveguide and Mach-Zehnder, which comprises a hollow silicon tube HST1, a single-mode optical fiber SMF2 and a capillary tube 4 as shown in figure 1. Two ends of the hollow silicon tube HST1 are respectively and symmetrically connected with a section of single mode fiber SMF2, and the sensing loop with a balloon structure is integrally formed. The other ends of the two single-mode optical fibers SMF2 respectively pass through the capillary microtubes 4. Wherein the hollow silicon tube HST1 has an inner diameter of 50 μm, an outer diameter of 125 μm and a length of 1.5 cm. The single mode fiber SMF2 is a communication single mode fiber. The capillary micro-tube 4 has an inner diameter of 1mm and an outer diameter of 1.5 mm.
The method for manufacturing the sensor comprises the following specific steps: firstly, stripping a section of single mode fiber SMF2 and a section of hollow silicon tube HST1 coating layer by using fiber pliers, wiping the coating layers by using cotton with alcohol, cutting the end faces of the single mode fiber SMF2 and the hollow silicon tube HST1 with the stripped coating layers to be flat by using a fiber cutter, then respectively putting the single mode fiber SMF2 and the hollow silicon tube HST 3538 into two ends of an optical fiber fusion splicer, and closing a clamp to prevent the single mode fiber SMF2 and the hollow silicon tube HST1 from loosening. And setting discharge parameters of the optical fiber fusion splicer, and fusing the single-mode optical fiber SMF2 and the hollow silicon tube HST1 by discharging. And opening the clamp, moving the hollow-core silicon tube HST1 with the help of the optical moving platform, cutting the length of the hollow-core silicon tube HST1 to be 1.5cm, and placing the cut section of the hollow-core silicon tube HST1 at one end of the optical fiber fusion splicer. And taking another section of single-mode fiber SMF2, stripping a coating layer by about 1cm, dipping cotton in alcohol to clean, cutting the end face of the single-mode fiber SMF2 with the coating layer stripped by an optical fiber cutter to be flat, then putting the single-mode fiber SMF2 into the other end of the optical fiber fusion splicer, closing a clamp, setting discharge parameters of the optical fiber fusion splicer, and discharging to fuse the hollow silicon tube HST1 and the single-mode fiber SMF 2. And bending the two sections of single-mode optical fibers SMF2 in the welded structure into a balloon structure through the capillary microtubes 4. Wherein the maximum bending diameter D is 1.2 cm.
The schematic diagram of the structure of the patent is shown in figure 1. When light enters the balloon structure, higher order cladding modes are excited due to mode field mismatch. The core mode and cladding mode continue to propagate within the hollow silicon tube HST1 until they leave the balloon structure. The incident light beams are combined and part of the excited cladding modes are coupled back into the core of the single mode fiber SMF 2. A typical MZI is formed due to the optical phase difference between the core mode and the excited cladding mode. The interference intensity and phase difference of MZI can be expressed as follows:
wherein I1And I2The light intensity of the fiber core mode and the high-order cladding mode respectively; n iscoAnd nclThe refractive indices of the core and cladding, respectively; λ is the wavelength of light in vacuum; l is1And L2The lengths of the single-mode optical fiber SMF2 and the hollow-core silicon tube HST1 related to interference respectively; n isairAnd nHSTRefractive indices of air and silica, respectively;
is the phase difference of two interfering lights: l isOPDIs a fiber coreThe optical path difference between the mode and the higher order cladding mode.
When the phase difference satisfies the condition
m＝0,1,2,…
Namely, it is
Interference valleys appear. Wherein m is an integer, λmThe wavelength of the mth order interference fringe.
For resonant reflection effects, the resonant wavelength λm′The cladding thickness d can be expressed as follows:
where m' is a positive integer representing the number of resonant stages, and nHSTIs the refractive index of silicon dioxide. The intensity of the transmission fringe can be expressed as:
wherein IArrowIs the intensity of the incident light at the resonant wavelength.
When the external temperature changes, the refractive indices of the core mode and the cladding mode will change, resulting in a change in the optical phase difference between the core mode and the higher-order mode, and hence the MZI fringes will shift. However, the high thermo-optic coefficient of quartz (1.2 × 10) is considered-5) And 5.5X 10-7The low coefficient of thermal expansion of/° c, temperature has less effect on the refractive index and thickness of the hollow silicon tube HST1, and therefore resonant transmitted light intensity is insensitive to temperature changes. With the change in curvature, the hollow core silicon tube HST1 is compressed on one side while the other side is stretched. This has two consequences, on the one hand, the core and cladding modes are propagating asymmetrically around the hollow core silica tube HST 1. Thus, the length of the MZI interference is all under different bending conditionsDifferent. Thus, the wavelength of the MZI moves with the change in curvature. On the other hand, when the curvature changes, the symmetry of the interference beam around the hollow-core silicon tube HST1 is broken: the optical path of the interference beam on the tension side increases, and the optical path of the interference beam on the compression side decreases. Considering that the incident angle of the guided light is limited, the light intensity at the resonance wavelength varies with the increase of the curvature. The optical path within the bent state hollow silicon tube HST1 is shown in fig. 2.
In view of the above sensor, a sensing experiment device can be constructed for detecting the displacement and/or temperature of the object to be measured. Firstly, a sensor probe is fixed on a glass sheet 5 by ultraviolet glue 3, then the glass sheet 5 is placed on an object to be detected, and two ends of the sensor are respectively connected with a light source BBS 6 and an optical spectrum analyzer OSA 7. In testing with the above described sensing device, it is necessary to verify the stability of the sensing device. Wherein, the light source BBS is a 6-spectral light source, and the minimum resolution OSA7 of the spectrum analyzer is 0.05 nm.
A displacement sensing experimental device as shown in fig. 3 can be constructed. In the displacement sensing verification experiment, the glass sheet 5 was vertically fixed to the displacement platform. The sensor is displaced by adjusting the displacement platform, an initial reflection spectral line is recorded when the displacement is 0 mu m, and the step length is 10 mu m when the displacement is increased from 0 mu m to 150 mu m. Then the displacement is reduced from 150 μm to 0 μm in steps of 10 μm, and 32 sets of data are recorded. Thereby verifying the stability of the sensor in displacement sensing.
A temperature sensing experimental set-up as shown in fig. 4 can be set up. In the temperature sensing verification experiment, the sensor is fixed by a glass sheet 5 and then placed in a temperature control box TC. The response of the sensor to the temperature is recorded by adjusting the temperature of the temperature control box, the initial reflection spectral line is recorded at 20 ℃, the initial reflection spectral line is recorded once every 10 ℃, and the initial reflection spectral line is recorded for 8 times from 20 ℃ to 90 ℃. Then the temperature is reduced from 90 ℃ to 20 ℃ by a step length of 10 ℃, and 16 groups of data are recorded. Thereby verifying the stability of the sensor in temperature sensing.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (8)
1. The sensor based on the resonant reflection waveguide and the Mach-Zehnder is characterized by comprising a hollow silicon tube HST (1), a single-mode fiber SMF (2) and a capillary micro-tube (4), wherein two ends of the hollow silicon tube HST (1) are respectively and symmetrically connected with a section of the single-mode fiber SMF (2) to form a sensing loop of a balloon structure integrally, and the other end of the single-mode fiber SMF (2) penetrates through the capillary micro-tube (4) respectively.
2. The resonant reflective waveguide and mach-zehnder based sensor according to claim 1, characterized in that the hollow-core silicon tube HST (1) has an inner diameter of 50 μ ι η, an outer diameter of 125 μ ι η, and a length of 1.5 cm.
3. The resonant reflective waveguide and mach-zehnder-based sensor according to claim 1, characterized in that the single-mode fiber SMF (2) is a communicating single-mode fiber.
4. A resonant reflective waveguide and mach-zehnder based sensor according to claim 1, characterized in that the capillary microtubes (4) have an inner diameter of 1mm and an outer diameter of 1.5 mm.
5. The resonant reflective waveguide and mach-zehnder-based sensor of claim 1, wherein a maximum bend diameter D of the sensing loop is 1.2 cm.
6. A sensing assay device comprising an ultraviolet glue (3), a glass plate (5), a light source BBS (6), a spectrum analyzer OSA (7) and a sensor according to any of claims 1-5, wherein the ultraviolet glue (3) fixes the sensor to the glass plate (5), and the sensor is connected to the light source BBS (6) and the spectrum analyzer OSA (7) at two ends.
7. A sensing experiment device according to claim 6, characterized in that the light source BBS (6) is a broad spectrum light source.
8. The sensing experiment device according to claim 6, characterized in that the minimum resolution of the OSA (7) is 0.05 nm.
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| CN115727882A (en) * | 2022-11-29 | 2023-03-03 | 北京航空航天大学 | Temperature and pressure double-parameter flexible optical fiber touch sensor, preparation method and measurement system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115727882A (en) * | 2022-11-29 | 2023-03-03 | 北京航空航天大学 | Temperature and pressure double-parameter flexible optical fiber touch sensor, preparation method and measurement system |
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