阅读说明：本技术 一种基于模间干涉的错位干涉传感器及其制备方法 (Dislocation interference sensor based on intermode interference and preparation method thereof ) 是由 王�琦 贾乃征 何东昌 伍卓慧 刘欣悦 汪友胜 于 2019-09-30 设计创作，主要内容包括：本发明提供了一种基于模间干涉的错位干涉传感器及其制备方法,其中,基于模间干涉的错位干涉传感器包括：单模光纤和和保偏光纤,单模光纤设置在保偏光纤光纤的两端,保偏光纤位于两单模光纤之间并沿单模光纤径向向下设置,使单模光纤与保偏光纤之间呈阶梯错落结构,保偏光纤可以重复使用,而将单模光纤设置在保偏光纤的两端,使单模光纤与保偏光纤之间呈阶梯错落结构,显著提高了错位干涉传感器的灵敏度,同时,结构简单,可反复使用,可重复性强,并能节约成本。(The invention provides a dislocation interference sensor based on intermode interference and a preparation method thereof, wherein the dislocation interference sensor based on intermode interference comprises the following components: single mode fiber and polarization maintaining fiber, single mode fiber sets up the both ends of polarization maintaining fiber optic fibre, polarization maintaining fiber is located between two single mode fiber and radially sets up downwards along single mode fiber, make to be the ladder structure of straying between single mode fiber and the polarization maintaining fiber, polarization maintaining fiber can used repeatedly, and single mode fiber sets up the both ends of polarization maintaining fiber, it is the ladder structure of straying to make between single mode fiber and the polarization maintaining fiber, the sensitivity of dislocation interference sensor has been showing to be improved, and simultaneously, moreover, the steam generator is simple in structure, can use repeatedly, and high repeatability, and can practice thrift the cost.)

1. A misalignment interference sensor based on intermodal interference, comprising: the single mode fiber and the polarization maintaining fiber are arranged at two ends of the polarization maintaining fiber, the polarization maintaining fiber is located between the two single mode fibers and is arranged downwards along the radial direction of the single mode fibers, and a stepped staggered structure is formed between the single mode fibers and the polarization maintaining fiber.

2. The positional interference sensor of claim 1, wherein the polarization maintaining fiber has a length of 9-10 mm.

3. The interferometric sensor of claim 2, wherein the single-mode fiber is fused to both ends of the polarization maintaining fiber, such that the single-mode fiber and the polarization maintaining fiber have a stepped configuration.

4. The shearing interference sensor of claim 3, wherein the shearing distance is 1/4 of the radius of the polarization maintaining fiber, and the shearing distance is a perpendicular distance from the polarization maintaining fiber to the upper edge of the end face of the single mode fiber spliced with the polarization maintaining fiber.

5. The shearing interference sensor of claim 4, wherein the optical power loss of the shearing structure between the single mode fiber and the polarization maintaining fiber is 30 dB.

6. The shearing interference sensor of any one of claims 1-5, wherein the polarization maintaining fiber is a tapered polarization maintaining fiber, and the upper and lower edges of the middle portion of the polarization maintaining fiber are recessed toward the central axis.

7. The shearing interference sensor of claim 6, wherein the tapered length of the polarization maintaining fiber is 10-15 mm.

8. A method for preparing a misalignment interference sensor based on intermode interference according to any one of claims 1 to 7, which comprises the following steps:

the method comprises the following steps: intercepting a polarization maintaining optical fiber, and intercepting a polarization maintaining optical fiber with one end of 10 mm;

step two: tapering the polarization maintaining fiber, and stretching the two ends of the polarization maintaining fiber by 10-15mm by using a tapering machine to enable the upper edge and the lower edge of the middle part of the polarization maintaining fiber to be sunken towards the central axis;

step three: the method comprises the following steps of staggered welding, namely utilizing a welding machine to weld the single-mode fibers to two sides of the polarization-maintaining fibers in a staggered mode, wherein the staggered distance is one fourth of the radius of the polarization-maintaining fibers, and the staggered distance is the vertical distance between the upper edge of the welded end face of the single-mode fibers and the polarization-maintaining fibers;

step four: and (3) detection, wherein two ends of the interference sensor are connected to the spectrometer and the light source, the sensor is fixed on the glass slide and is placed in clear water for detection, and if the spectrometer displays obvious interference fringes, the manufacturing is successful.

Technical Field

The invention relates to the technical field of optical fiber sensors, in particular to a dislocation interference sensor based on intermode interference and a preparation method thereof.

Background

Intermodal interference is a common interference phenomenon. The method is characterized in that beam splitting and beam combining of incident light are respectively realized at the front position and the rear position of the same optical fiber, and when the incident light and the beam combining meet the phase difference, interference fringes are generated, so that the measurement of the external physical environment is realized.

The Mach-Zehnder interferometer is a sensor based on the principle of two-beam interference, where light is split into a measurement arm and a reference arm by some means, and then they are combined together, where the interference phenomenon can be formed by measurement. The sensing measurement of physical quantities such as temperature, refractive index, bending and the like is realized through interference phenomenon.

The Mach-Zehnder interferometers are further classified into a conventional type and an embedded type. And the optical fiber dislocation welding belongs to an embedded Mach-Zehnder interferometer. The embedded Mach-Zehnder interferometer leads the fiber core light to enter the cladding layer to realize the excitation of a cladding layer mode in a dislocation mode, after the light enters the optical fiber, the fiber core becomes a measuring arm, the cladding layer becomes a reference arm, and interference fringes are formed through the difference of modes.

A polarization maintaining fiber is an optical fiber that amplifies the birefringence of light and is also called a sensitivity enhancing fiber. When light passes through the polarization maintaining fiber, the light is divided into a fast axis and a slow axis, and the dispersion generated in the conventional single mode fiber can be reduced by the transmission of the fast axis and the slow axis. Polarization maintaining optical fibers are commonly used in sensors to serve to increase the sensitivity of the sensor. The polarization maintaining fiber can form a micro-nano high birefringent fiber through tapering, and is generally applied to a Sagnac interferometer.

Disclosure of Invention

In order to solve the problem of low sensitivity of the existing optical fiber dislocation welding, the invention provides a dislocation interference sensor based on intermode interference in a first aspect, and provides a preparation method of the dislocation interference sensor based on intermode interference in a second aspect.

In view of the above, the first aspect of the present invention provides a misalignment interference sensor based on inter-mode interference, comprising:

the single mode fiber and the polarization maintaining fiber are arranged at two ends of the polarization maintaining fiber, the polarization maintaining fiber is located between the two single mode fibers and is arranged downwards along the radial direction of the single mode fibers, and a stepped staggered structure is formed between the single mode fibers and the polarization maintaining fiber.

Preferably, the length of the polarization maintaining fiber is 9-10 mm.

Preferably, the single-mode fiber is fused to both ends of the polarization maintaining fiber, so that the single-mode fiber and the polarization maintaining fiber have a stepped staggered structure.

Preferably, the offset distance is 1/4 of the radius of the polarization maintaining fiber, and the offset distance is the perpendicular distance from the polarization maintaining fiber along the end face where the single mode fiber and the polarization maintaining fiber are welded.

Preferably, the optical power loss of the staggered structure between the single-mode fiber and the polarization maintaining fiber is 30 dB.

Preferably, the polarization maintaining fiber is a tapered polarization maintaining fiber, and the upper edge and the lower edge of the middle part of the polarization maintaining fiber are recessed towards the central axis.

Preferably, the taper length of the polarization maintaining optical fiber is 10-15 mm.

The second aspect of the present invention provides a method for manufacturing a misalignment interference sensor based on intermode interference according to any of the above technical solutions, including the following steps:

the method comprises the following steps: intercepting a polarization maintaining optical fiber, and intercepting a polarization maintaining optical fiber with one end of 10 mm;

step two: tapering the polarization maintaining fiber, stretching the two ends of the polarization maintaining fiber by 10-15mm with a tapering machine to make the upper edge and the lower edge of the middle part of the polarization maintaining fiber dent towards the central axis,

step three: and (3) dislocation welding, namely respectively performing dislocation welding on the single-mode optical fibers on two sides of the polarization-maintaining optical fiber by using a welding machine, wherein the dislocation distance is 1/4 of the radius of the polarization-maintaining optical fiber, and the dislocation distance is the vertical distance between the upper edge of the end face of the single-mode optical fiber and the polarization-maintaining optical fiber in welding and from the polarization-maintaining optical fiber.

Step four: and (3) detection, wherein two ends of the sensor are connected to the spectrometer and the light source, the sensor is fixed on the glass slide and is placed in clear water for detection, and if the spectrometer displays obvious interference fringes, the manufacturing is successful.

Compared with the prior art, the invention has the beneficial effects that: compared with the existing single-mode structure, the sensor has the advantages of obviously improved sensitivity, high manufacturing power, repeated use and strong repeatability, and compared with a sensor with the same order of magnitude, the sensor has relatively low manufacturing cost.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

FIG. 1 shows a schematic structural diagram of a misalignment interference sensor according to one embodiment of the invention;

FIG. 2 is a schematic structural framework diagram illustrating a method for fabricating a misalignment interference sensor according to an embodiment of the invention for detecting the misalignment interference sensor;

FIG. 3 shows a measured spectral plot of a displaced interferometric sensor according to one embodiment of the invention;

FIG. 4 illustrates a sensitivity line fit curve of a misaligned interferometric sensor before tapering, according to one embodiment of the invention;

FIG. 5 illustrates a sensitivity line-fit curve after tapering of a misaligned interferometric sensor according to one embodiment of the invention;

FIG. 6 shows a schematic flow diagram of a method of fabricating a misalignment interference sensor according to one embodiment of the invention.

Wherein: 1. a single mode optical fiber; 2. a polarization maintaining fiber.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

A misalignment interference sensor based on intermodal interference and a method of fabricating the same according to some embodiments of the present invention are described below with reference to fig. 1 to 6.

In an embodiment of the first aspect of the present invention, as shown in fig. 1, the present invention provides a misalignment interference sensor based on inter-mode interference, including: single mode fiber 1 and polarization maintaining fiber 2, single mode fiber 1 sets up the both ends of polarization maintaining fiber 2 optic fibre, and polarization maintaining fiber 2 is located between two single mode fiber 1 and radially sets up downwards along single mode fiber 1, makes to be the ladder structure of straying between single mode fiber 1 and the polarization maintaining fiber 2.

In this embodiment, the polarization maintaining fiber 2 can be used repeatedly, the single mode fiber 1 is disposed at two ends of the polarization maintaining fiber 2, the polarization maintaining fiber 2 is disposed between the two single mode fibers 1 and disposed downward along the radial direction of the single mode fiber 1, and is connected with the two single mode fibers 1, so that the two single mode fibers 1 and the polarization maintaining fiber 2 are in a stepped staggered structure, the sensitivity of the staggered interference sensor is significantly improved, and meanwhile, the staggered interference sensor has the advantages of simple structure, repeated use, strong repeatability and cost saving.

In one embodiment of the present invention, the length of the polarization maintaining fiber 2 is preferably 9-10 mm.

In this embodiment, the length of the polarization maintaining fiber 2 is 9-10mm, and the number of the wave troughs on the spectrometer is moderate, so that the wave trough drift degree can be conveniently detected and observed. Meanwhile, the sensitivity of the dislocation interference sensor is high.

In one embodiment of the present invention, preferably, as shown in fig. 1, the single-mode fiber 1 is fused to both ends of the polarization maintaining fiber 2, so that the single-mode fiber 1 and the polarization maintaining fiber 2 have a stepped staggered structure.

In this embodiment, two single-mode optical fibers 1 are fused to two ends of the polarization maintaining optical fiber 2 by a fusion splicer such as a japanese gulhe S117 fusion splicer, and the fusion splicing method is adopted, so that the optical fiber connection loss is low, the method is safe and reliable, the influence of external factors is small, the equipment model is only an example, and the invention is not limited thereto.

In one embodiment of the present invention, preferably, the offset distance is 1/4 of the radius of the polarization maintaining fiber 2, and the offset distance is the perpendicular distance from the polarization maintaining fiber 2 along the end face where the single mode fiber 1 is fusion spliced with the polarization maintaining fiber 2.

In this embodiment, the misalignment distance is 1/4 of the radius of the polarization maintaining fiber 2, the depth of the wave trough of the spectrometer is moderate at this time, the wavelength value of the light source corresponding to the wave trough at this time can be rapidly detected by the spectrometer, and meanwhile, the sensitivity of the misalignment interference sensor is high.

In one embodiment of the present invention, the optical power loss of the misclassification structure between the single-mode fiber 1 and the polarization-maintaining fiber 2 is preferably 30 dB.

In this embodiment, the optical power loss of the staggered structure between the single mode fiber 1 and the polarization maintaining fiber 2 is 30dB, and the staggered fusion splicing is successful.

In one embodiment of the present invention, preferably, as shown in fig. 1, the polarization maintaining fiber 2 is a tapered polarization maintaining fiber 2, and the upper edge and the lower edge of the middle portion of the polarization maintaining fiber 2 are recessed toward the central axis.

In this embodiment, a tapering machine, such as an IPCS-5000 tapering machine, is used to taper the polarization maintaining fiber, and when the polarization maintaining fiber 2 is tapered, due to the reduction of the radius of the tapering machine, the birefringence effect and the large evanescent field effect of the polarization maintaining fiber 2 are increased, so as to improve the different influences of the sensor on the refractive index of the surrounding medium, thereby increasing the sensitivity.

In one embodiment of the present invention, the tapered length of the polarization maintaining fiber 2 is preferably 10-15 mm.

In the embodiment, the taper length of the polarization maintaining optical fiber 2 is 10-15mm, and the sensitivity of the dislocation interference sensor is high

In an embodiment of the second aspect of the present invention, as shown in fig. 6, the present invention provides a method for preparing a misalignment interference sensor based on inter-mode interference according to any one of the above embodiments, including the following steps:

the method comprises the following steps: intercepting a polarization maintaining optical fiber 2, and intercepting a polarization maintaining optical fiber 2 with one end of 10 mm;

step two: tapering the polarization maintaining fiber 2, stretching the two ends of the polarization maintaining fiber 2 by 10-15mm by using a tapering machine to make the upper edge and the lower edge of the middle part of the polarization maintaining fiber 2 concave towards the central axis,

step three: and (3) dislocation welding, namely respectively performing dislocation welding on the single-mode optical fiber 1 on two sides of the polarization-maintaining optical fiber 2 by using a welding machine, wherein the dislocation distance is 1/4 of the radius of the polarization-maintaining optical fiber 2, and the dislocation distance is the vertical distance between the upper edge of the end face of the single-mode optical fiber 1 welded with the polarization-maintaining optical fiber 2 and the polarization-maintaining optical fiber 2.

Step four: and (3) detection, wherein two ends of the dislocation interference sensor are connected to the spectrometer and the light source, the sensor is fixed on the glass slide, the glass slide is put into clear water for detection and is analyzed by a computer, and if the spectrometer displays obvious interference fringes, the manufacturing is successful.

The invention provides a preparation method of a dislocation interference sensor based on intermode interference, which comprises the steps of firstly cutting a section of polarization maintaining optical fiber 2 with the thickness of about 10mm, and stretching the middle part of the polarization maintaining optical fiber 2 by a tapering machine for 10-15 mm. And then carrying out dislocation fusion on the single-mode optical fiber 1 and the polarization maintaining optical fiber 2 twice by using a fusion splicer, wherein the dislocation distance is 1/4 of the radius of the polarization maintaining optical fiber 2, the dislocation distance is less than 1/4 of the radius of the polarization maintaining optical fiber, and the wave trough is not obvious. As shown in fig. 2, after the staggered melting is finished, two ends of the staggered interference sensor are connected to a spectrometer and a light source, the spectrometer adopts a japanese river crossing AQ6375B spectrometer, the light source is a marine optics hl2000HP, the staggered interference sensor is fixed on a glass slide and directly put into clear water for detection, and the clear water is analyzed by a computer, if the spectrometer displays obvious interference fringes, the manufacturing is successful, the device model is only an example, and the invention is not limited to the device model.

The improvement of the sensitivity of the dislocation interference sensor is researched, the light source adopts a light source with the wavelength range of 1525 and 1625nm, and the supercontinuum is used for recording the resonance spectrum. A sodium chloride salt solution having a refractive index varying in the range of 1.3310-1.3370 was prepared, and the refractive index value thereof was measured by Abbe refractometer. In the measurement, a finite element analysis method was used for analysis.

As shown in FIG. 3, the resonance valley drifts to the right and then settles at a fixed value over a range of index changes 1.3320-1.3370. When the refractive index is outside, the wavelength of the spectral wave trough on the spectrometer can drift, the refractive index of the solution can be measured by detecting the wavelength value of the wave trough, the drift amount of the wave trough and the change amount of the refractive index are in a linear relation, the slope of a straight line which is fitted by the drift amount of the wave trough and the change amount of the refractive index is sensitivity, the higher the sensitivity is, the higher the drift amount of the wave trough is, and the better the detection accuracy is. As shown in fig. 4, it can be seen from the fact that y is 574.336x +821.90, the sensitivity of the polarization maintaining fiber 2 is only 574.3nm/RIU without tapering. After tapering, as shown in fig. 5, as y is 14407.0992+9656x, the sensitivity can be increased to 9656nm/RIU, and the sensitivity is greatly improved.

In the description of the present invention, the terms "plurality" or "a plurality" refer to two or more, and unless otherwise specifically limited, the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are merely for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention; the terms "connected," "mounted," "secured," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present invention, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In the present invention, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be used in any one or more embodiments or examples.