CN117490737A - MZI sensor with direct welding and preparation method - Google Patents
MZI sensor with direct welding and preparation method Download PDFInfo
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- 238000003466 welding Methods 0.000 title claims description 22
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 239000000835 fiber Substances 0.000 claims abstract description 124
- 230000008878 coupling Effects 0.000 claims abstract description 107
- 238000010168 coupling process Methods 0.000 claims abstract description 107
- 238000005859 coupling reaction Methods 0.000 claims abstract description 107
- 239000013307 optical fiber Substances 0.000 claims abstract description 59
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- 230000005540 biological transmission Effects 0.000 claims abstract description 9
- 238000001228 spectrum Methods 0.000 claims abstract description 8
- 230000004927 fusion Effects 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 6
- 239000011247 coating layer Substances 0.000 claims description 4
- 238000007526 fusion splicing Methods 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 abstract description 11
- 230000009286 beneficial effect Effects 0.000 abstract description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35329—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using interferometer with two arms in transmission, e.g. Mach-Zender interferometer
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
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Abstract
The invention provides a direct-welded MZI sensor and a preparation method thereof, and belongs to the technical field of optical fiber sensing. The technical problem that the structure, cost and performance of the existing sensor cannot be combined is solved. The technical proposal is as follows: the MZI sensor comprises a beam splitting coupling point and a beam combining coupling point which are sequentially arranged along the transmission direction, an interference arm and a reference arm which are arranged between the beam splitting coupling point and the beam combining coupling point, a first single mode fiber and a second single mode fiber which are arranged outside the beam splitting coupling point, and a third single mode fiber and a fourth single mode fiber which are arranged outside the beam combining coupling point; when the device is used, the second single mode fiber is connected with the broadband light source, the fourth single mode fiber is connected with the spectrum analyzer, and the first single mode fiber and the third single mode fiber are respectively suspended. The beneficial effects of the invention are as follows: the MZI sensor directly welded is simple in structure, easy to manufacture, low in cost and high in sensitivity.
Description
Technical Field
The invention relates to the technical field of optical fiber sensing, in particular to a direct-welded MZI sensor and a preparation method thereof.
Background
In recent years, optical fibers are widely used in the manufacture of sensors due to the advantages of simple structure, light weight, small volume, electromagnetic interference resistance and the like. Compared with the traditional electronic sensor, the optical fiber has the advantages that the optical fiber is more suitable for application in severe environments and can be produced at low cost, so that the optical fiber is widely applied to detection of parameters such as temperature, curvature, strain, refractive index, air pressure and the like. To date, optical fiber sensors, especially optical fiber curvature sensors, have played a vital role in the fields of medical equipment, engineering structure detection, national defense, etc., and the development of sensors has been toward miniaturization and precise control.
Currently, among the known optical fiber sensor structures, MZI is favored by researchers because of its simple structure and good sensing effect. The conventional two-arm MZI is formed by cascading two couplers, so that the two arms are in the order of meters in size. The two-arm meter-level MZI has the advantages of high measurement accuracy and the like due to the advantages of mutual independence between the two arms and mutual noninterference between optical paths. However, the two arms of the meter level are too large and have the defects of large volume, difficult integration, easy interference by external environment and the like. In recent years, researchers have proposed miniaturized all-fiber online MZI (In-line Mach-Zehnder interferometer, IMZI) to make fiber optic sensors more lightweight and easy to integrate. However, because the generation of the high-order mode is based on the excitation of the fundamental mode of the fiber core, when the external environment changes, the fundamental mode and the high-order mode change simultaneously, so that the two modes are difficult to separate under the influence of the external environment, and the high-sensitivity detection and the applicability of the device are limited. Meanwhile, in order to realize high-sensitivity detection, a complex structure is required to be welded, and the manufacturing difficulty of the device is increased.
In order to improve the application range of the MZI optical fiber device, the miniaturized accurate sensing requirement is met. The dual-arm MZI provides a great advantage over the in-line single-arm MZI in both device design parameter tuning and sensor performance contrast. So far, little research has been done on miniaturizing conventional dual-arm MZI (on the order of centimeters). How to keep the crosstalk-free characteristic of the two-arm MZI at the same time, the advantages of miniaturization, easy packaging and the like of the IMZI are achieved, the novel field is not researched, the defect of the field is the resistance of the development of the current optical fiber sensor, and the development of the MZI optical fiber sensor to multiple dimensions is limited.
How to solve the technical problems is the subject of the present invention.
Disclosure of Invention
The invention aims to provide the MZI sensor which is directly welded and has the advantages of simple structure, easy manufacture, low cost and high sensitivity, and the sensor preparation method which has the advantages of simple steps and operation, low manufacture difficulty and low cost and is suitable for mass production.
In order to achieve the aim of the invention, the invention adopts the technical scheme that: the MZI sensor comprises a beam splitting coupling point and a beam combining coupling point which are sequentially arranged along the transmission direction, an interference arm and a reference arm which are arranged between the beam splitting coupling point and the beam combining coupling point, a first single mode fiber and a second single mode fiber which are arranged outside the beam splitting coupling point, and a third single mode fiber and a fourth single mode fiber which are arranged outside the beam combining coupling point, wherein the first single mode fiber and the second single mode fiber are arranged outside the beam combining coupling point;
when the device is used, the second single mode fiber is connected with the broadband light source, the fourth single mode fiber is connected with the spectrum analyzer, and the first single mode fiber and the third single mode fiber are respectively suspended.
The two sections of single-mode fibers, namely the interference arm and the reference arm, which are positioned between the beam splitting coupling point and the beam combining coupling point are similar to the two arms of the traditional meter-level MZI, because the light in the two arms is limited in the respective single-mode fibers, the two different modes are respectively and independently transmitted, and the higher-order modes are relatively free from the influence of external physical parameters and are not influenced by the core mode, thereby obtaining better sensitivity and crosstalk resistance.
The input end of the interference arm is the first single mode fiber, and the output end of the interference arm is the third single mode fiber;
the input end of the reference arm is the second single mode fiber, and the output end of the reference arm is the fourth single mode fiber;
the optical path propagation sequence of the directly welded MZI sensor is as follows:
after the incident light output by the broadband light source enters the beam splitting coupling point through the second single mode fiber, one part of the light still propagates along the reference arm as a fiber core mode, and the other part of the light is excited into a high-order mode and is coupled into the interference arm. When light in the two arms simultaneously propagates to the beam combining coupling point, light with different modes is converged, interference is formed at the beam combining coupling point due to phase difference between the light with different modes, and finally, the light is conducted to the spectrum analyzer through the fourth single mode fiber, and the transmission spectrum is monitored.
Further, the first single mode fiber, the interference arm and the third single mode fiber are located at one side of a connecting line of the beam splitting coupling point and the beam combining coupling point, and the second single mode fiber, the reference arm and the fourth single mode fiber are located at the other side of the connecting line of the beam splitting coupling point and the beam combining coupling point.
Further, the first single mode optical fiber, the second single mode optical fiber, the third single mode optical fiber and the fourth single mode optical fiber are common single mode optical fibers respectively.
Further, the directly welded MZI sensor is manufactured by welding two non-intersecting single-mode fibers at two ends and forming the beam splitting coupling point and the beam combining coupling point respectively, the first single-mode fiber, the interference arm and the third single-mode fiber are located on one single-mode fiber, and the second single-mode fiber, the reference arm and the fourth single-mode fiber are located on the other single-mode fiber.
Further, the two single-mode fibers are parallel to each other, and after welding, the two single-mode fibers are smoothly transited to the two sides of the beam splitting coupling point and the two sides of the beam combining coupling point, referring to fig. 1, the main parts of the first single-mode fiber and the second single-mode fiber, the main parts of the interference arm and the reference arm, and the main parts of the third single-mode fiber and the fourth single-mode fiber are parallel to each other.
Further, a distance range between the beam splitting coupling point center and the beam combining coupling point center is set to be 3-8cm.
Further, the distance between the beam splitting coupling point center and the beam combining coupling point center is set to 5cm, and compared with other lengths, since the free spectral range is inversely proportional to the interference length, a longer length forms a fairly dense comb spectrum, while a too short length makes it difficult to find a suitable interference valley in a selected spectral range.
In order to better achieve the above object, the present invention further provides a method for preparing the directly welded MZI sensor, comprising the following steps:
step S1: intercepting two sections of single-mode optical fibers, preferably intercepting two sections of common single-mode optical fibers with equal length, marking equal length in the middle of the two sections of single-mode optical fibers respectively, and removing a coating layer at the marking position;
step S2: simultaneously placing two sections of single-mode optical fibers on a welding machine, and disposing the same end mark at the center of the welding machine for welding treatment to form the beam splitting coupling point/the beam combining coupling point;
step S3: moving the two sections of single-mode optical fibers, and disposing the marks at the center of a welding machine to weld so as to form the beam combination coupling point/the beam splitting coupling point;
further, in the step S3, before the other end mark is disposed at the center of the fusion splicer to perform fusion splicing treatment, two sections of the single-mode optical fibers are simultaneously straightened.
Further, specific parameters of the welding process in steps S2 and S3 are as follows: the manual mode (MM-MM) is used for three times of discharge, the discharge intensity is 250J, compared with the conventional SM-SM mode of single-mode welding and the low discharge intensity of about 120J, the parameter is more favorable for stably and effectively preparing the sensor, and the length of the coupling region can be controlled by changing the discharge quantity and the discharge times.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the traditional Mach-Zehnder interferometer, the sensor provided by the invention can control the length of the coupling region and the equivalent refractive index of the fiber core by controlling the discharge intensity and the discharge times, so that the coupling light splitting proportion is controlled, which cannot be achieved by the traditional MZI. Furthermore, the length of the coupling area obtained by the arc discharge method is only in the order of micrometers, compared with the traditional MZI light splitting mode, the coupling area with the size enables the whole structure of the sensor to be smaller, the size of the whole sensor is only in the order of centimeters, the smaller size allows the sensor to measure under various environments, portability and high sensitivity are achieved, packaging is facilitated, and multiple system integration or cascading with other devices can be achieved. In addition, the strong discharge coupling of the two optical fibers ensures that the refractive index of the optical fiber core of the coupling region has a homogenization effect, namely the refractive index distribution of the two optical fibers after discharge is relatively uniform. The homogenization of the refractive index of the fiber core ensures that light can be split by the coupling length of the micron order, and the miniaturization of the preparation device is ensured;
2. compared with the traditional online Mach-Zehnder interferometer, the sensor provided by the invention has the advantages that the high-order mode and the fiber core mode of the sensor are respectively transmitted in two sections of different single-mode fibers, when the external environment is changed, the change of the high-order mode and the fiber core mode is independent, the crosstalk problem between the two modes is avoided, and the sensitivity is improved. Meanwhile, in order to improve the sensitivity, the online Mach-Zehnder interferometer needs to introduce special optical fibers with high price or weld complex structures, and the structure only needs to weld single-mode optical fibers with low price directly, is low in cost, is easy to manufacture, and is more suitable for batch production.
3. Compared with the traditional micro-optical fiber Mach-Zehnder interferometer, the structure is prepared by using an optical fiber fusion splicer instead of using an optical fiber tapering machine with high price and large volume. Meanwhile, the waist cone area of the micro optical fiber is of nanometer order in diameter, so that the sensor manufactured by the micro optical fiber is poor in structural rigidity and difficult to package. The structure has the advantages of extremely high sensitivity, high structural rigidity, wider detection range and more application scenes, and is suitable for detection in severe environments or high-intensity motions.
4. The sensor provided by the invention has good response to curvature and is insensitive to temperature, so that the problem of cross sensitivity is effectively avoided;
5. the sensor provided by the invention has the advantages of small volume, simple structure, low cost, simple manufacture, high sensitivity, good robustness and the like, and has good application prospect in the fields of biological detection, environmental monitoring and the like;
6. the preparation method of the sensor provided by the invention has the advantages of simple steps and operation, low manufacturing difficulty and low cost, and is suitable for mass production.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention.
FIG. 1 is a schematic diagram I of the structure of the present invention;
FIG. 2 is a schematic diagram II of the structure of the present invention;
FIG. 3 is a schematic view of the apparatus of the present invention for performing curvature measurements;
FIG. 4 is a graph of the transmitted intensity (Y) shift as a function of curvature (C) for the present invention;
FIG. 5 is a graph of the resulting curvature (C) and transmission intensity (Y) for the trough of FIG. 3;
FIG. 6 is a schematic view of the apparatus for temperature measurement according to the present invention;
FIG. 7 is a graph of transmission loss shift with temperature change in accordance with the present invention;
FIG. 8 is a display of two optical fibers simultaneously placed on a fusion splicer;
fig. 9 is a display result on the fusion machine after fusion.
Wherein, the reference numerals are as follows: 1. a broadband light source; 2. a first single mode optical fiber; 3. a second single mode optical fiber; 4. beam splitting coupling points; 5. an interference arm; 6. a reference arm; 7. a beam combining coupling point; 8. a third single mode optical fiber; 9. a fourth single mode optical fiber; 10. a spectrometer; 11. a translation stage; 12. a screw micrometer.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. Of course, the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.
Example 1
The invention provides a direct welding MZI sensor, which comprises a beam splitting coupling point 4, a beam combining coupling point 7, an interference arm 5, a reference arm 6, a first single mode fiber 2, a second single mode fiber 3, a third single mode fiber 8 and a fourth single mode fiber 9, wherein the beam splitting coupling point 4 and the beam combining coupling point 7 are sequentially arranged along the transmission direction, the interference arm 5 and the reference arm 6 are arranged between the beam splitting coupling point 4 and the beam combining coupling point 7, the first single mode fiber 2 and the second single mode fiber 3 are arranged outside the beam splitting coupling point 4, and the third single mode fiber 8 and the fourth single mode fiber 9 are arranged outside the beam combining coupling point 7;
the first single-mode optical fiber 2, the second single-mode optical fiber 3, the third single-mode optical fiber 8 and the fourth single-mode optical fiber 9 are respectively common single-mode optical fibers.
The first single mode fiber 2, the interference arm 5 and the third single mode fiber 8 are positioned on one side of the connecting line of the beam splitting coupling point 4 and the beam combining coupling point 7, and the second single mode fiber 3, the reference arm 6 and the fourth single mode fiber 9 are positioned on the other side of the connecting line of the beam splitting coupling point 4 and the beam combining coupling point 7.
When in use, the second single-mode fiber 3 is connected with the broadband light source 1, the fourth single-mode fiber 9 is connected with the spectrum analyzer 10, and the first single-mode fiber 2 and the third single-mode fiber 8 are respectively suspended.
The input end of the interference arm 5 is a first single-mode optical fiber 2, and the output end is a third single-mode optical fiber 8;
the input end of the reference arm 6 is a second single-mode optical fiber 3, and the output end is a fourth single-mode optical fiber 9;
the optical path propagation sequence of the directly welded MZI sensor is as follows:
after the incident light output by the broadband light source 1 enters the beam splitting coupling point 4 through the second single mode fiber 3, a part of the light still propagates along the reference arm 6 as a fiber core mode, and the other part of the light is excited into a higher-order mode and is coupled into the interference arm 5. When light in the two arms propagates to the beam combining coupling point 7 at the same time, light in different modes is converged, interference is formed at the beam combining coupling point 7 due to a phase difference between the light in different modes, and finally, the light is conducted to the spectrum analyzer 10 through the fourth single mode fiber 9, so that transmitted light is monitored.
Example 2
Referring to fig. 1, on the basis of embodiment 1, the MZI sensor of direct fusion splice is made by fusing two single-mode fibers that are not crossed at both ends and forming a beam splitting coupling point 4 and a beam combining coupling point 7, respectively, the first single-mode fiber 2, the interference arm 5, the third single-mode fiber 8 being located on one of the single-mode fibers, and the second single-mode fiber 3, the reference arm 6, the fourth single-mode fiber 9 being located on the other single-mode fiber.
The preparation method of the MZI sensor directly welded in the embodiment comprises the following steps:
step S1: intercepting two sections of single-mode fibers, marking a distance of 3-8cm in the middle of each section of single-mode fibers, and removing a coating layer at the marked position;
step S2: simultaneously placing two sections of single-mode optical fibers on a fusion splicer, placing the same end mark at the center of the fusion splicer (the optical fiber fusion splicer is of the model of FURUKAWA S178C), discharging three times by using a manual mode, and performing fusion treatment with the discharge intensity of 250J to form a beam splitting coupling point 4/a beam combining coupling point 7;
step S3: moving two sections of single-mode fibers, disposing the other end mark at the center of a welding machine, discharging for three times by using a manual mode, wherein the discharge intensity is 250J, and performing welding treatment to form a beam combination coupling point 7/beam splitting coupling point 4;
example 3
Referring to fig. 1, based on embodiment 1, two single-mode fibers are parallel to each other, and after welding, the two single-mode fibers are smoothly transitioned at two sides of the beam splitting coupling point 4 and two sides of the beam combining coupling point 7, respectively, and the main parts of the first single-mode fiber 2 and the second single-mode fiber 3, the main parts of the interference arm 5 and the reference arm 6, and the main parts of the third single-mode fiber 8 and the fourth single-mode fiber 9 are parallel to each other. The distance between the center of the beam splitting coupling point 4 and the center of the beam combining coupling point 7 was set to 5cm.
The preparation method of the MZI sensor directly welded in the embodiment comprises the following steps:
step S1: intercepting two sections of single-mode fibers with equal length, wherein the two sections of single-mode fibers are common single-mode fibers, marking a distance of 5cm at the centers of the two sections of single-mode fibers respectively, and removing a coating layer at the marked positions;
step S2: simultaneously placing two sections of single-mode fibers on a fusion splicer, placing the same end mark at the center of the fusion splicer (the optical fiber fusion splicer is of the model of FURUKAWA S178C), stretching the two sections of single-mode fibers, and horizontally and parallelly distributing the two sections of single-mode fibers, discharging three times by using a manual mode, wherein the discharge intensity is 250J, and performing fusion treatment to form a beam splitting coupling point 4/a beam combining coupling point 7;
step S3: moving two sections of single-mode fibers, placing the other end mark at the center of a fusion splicer (optical fiber fusion splicer, model is FURUKAWA S178C), simultaneously, after stretching the two sections of single-mode fibers, discharging for three times by using a manual mode, wherein the discharge intensity is 250J, performing fusion treatment to form a beam-combining coupling point 7/beam-splitting coupling point 4, and stretching the two sections of single-mode fibers to enable the two optical fibers to be horizontally and parallelly distributed on the fusion splicer, so that the electric quantity is uniform in the fusion splicing discharge process, and the transmission spectrum of the sensor has good beam splitting ratio and the refractive index distribution of the fused optical fiber coupler is uniform.
The connecting lines between the beam combining coupling points 7 and the beam splitting coupling points 4 of the directly welded MZI sensor manufactured by the manufacturing method are straight, and referring to FIG. 2, the main body parts of the interference arm 5 and the reference arm 6 are respectively parallel to the connecting lines.
The two fibers after strong discharge are well welded, the refractive index inside the fiber cores is uniformly distributed, and high-quality coupling of light is ensured, as shown in fig. 9.
By increasing the number of discharges, the length of the coupling interval and the refractive index inside the coupler can be changed, thereby adjusting the coupling efficiency. And excessive discharge will saturate the length of the coupling point and the internal effective refractive index, and no change occurs.
Curvature measurement was performed on a MZI sensor (hereinafter referred to as a sensor) directly welded in the present embodiment, and the apparatus is as shown in fig. 2:
the sensor of this embodiment is fixed on two translation stages 11 by using a spiral micrometer 12, that is, the beam splitting coupling point 4 is fixed on one translation stage 11, the beam combining coupling point 7 is fixed on the other translation stage 11, the spiral micrometer 12 on the translation stage 11 is rotated to change the distance between the two translation stages 11, and the overall bending between the beam splitting coupling point 4 and the beam combining coupling point 7 in the sensor, that is, the curvature is indirectly changed by changing the curvature radius, as shown in fig. 3, when the curvature is changed, the position of the trough on the spectrum analyzer is lowered; the transmission loss (Y) and the curvature (C) are linearly related, and as shown in FIG. 4, the curvature sensitivity of the trough is as high as-112.458 dB/m -1 And meanwhile, the linearity reaches 0.98851, so that the curvature measurement is facilitated, namely, the sensor has good response to the curvature.
The temperature measurement is performed on the sensor in this embodiment, and the apparatus is as shown in fig. 5:
wherein the sensor parts, namely the beam splitting coupling point 4, the beam combining coupling point 7 and the parts between the two, are placed in a platform of the constant temperature box 13 and are covered by a constant temperature box cover. By changing the temperature of the incubator, we obtain an offset graph of the interference valley of the transmission spectrum with the change of the temperature (T), as shown in FIG. 6, when the temperature changes, the position of the trough on the spectrometer shifts to the right, no obvious offset is seen on the transmission loss, the maximum transmission loss offset is only 0.651dB, and the curvature sensitivity of the temperature sensor is almost negligible compared with the hundred-bit order, which means that the temperature does not influence the curvature measurement of the temperature sensor by intensity modulation, namely the sensor is insensitive to the temperature.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The MZI sensor is characterized by comprising a beam splitting coupling point (4) and a beam combining coupling point (7) which are sequentially arranged along the transmission direction, an interference arm (5) and a reference arm (6) which are arranged between the beam splitting coupling point (4) and the beam combining coupling point (7), a first single mode fiber (2) and a second single mode fiber (3) which are arranged outside the beam splitting coupling point (4), and a third single mode fiber (8) and a fourth single mode fiber (9) which are arranged outside the beam combining coupling point (7);
when the single-mode optical fiber is used, the second single-mode optical fiber (3) is connected with the broadband light source (1), the fourth single-mode optical fiber (9) is connected with the spectrum analyzer (10), and the first single-mode optical fiber (2) and the third single-mode optical fiber (8) are respectively suspended.
2. The directly welded MZI sensor of claim 1, wherein said first single mode fiber (2), said interference arm (5), said third single mode fiber (8) are located on one side of said beam splitting coupling point (4) and said beam combining coupling point (7), and said second single mode fiber (3), said reference arm (6), said fourth single mode fiber (9) are located on the other side of said beam splitting coupling point (4) and said beam combining coupling point (7).
3. The directly fused MZI sensor of claim 1 or 2, wherein said first single mode fiber (2), said second single mode fiber (3), said third single mode fiber (8), said fourth single mode fiber (9) are each a common single mode fiber.
4. A directly welded MZI sensor as in any of the claims 1-3, characterized by said directly welded MZI sensor being made by welding two single mode fibers at both ends, which are not crossed, and forming said split coupling point (4) and said combined coupling point (7), respectively, said first single mode fiber (2), said interference arm (5), said third single mode fiber (8) being located on one of said single mode fibers, said second single mode fiber (3), said reference arm (6), said fourth single mode fiber (9) being located on the other of said single mode fibers.
5. The directly welded MZI sensor of claim 4, wherein two single mode fibers are parallel to each other, and the two sides of said beam splitting coupling point (4) and the two sides of said beam combining coupling point (7) are smoothly transitioned after welding.
6. The directly welded MZI sensor of any of the claims 1-5, characterized in that the distance between the centre of said beam splitting coupling point (4) and the centre of said beam combining coupling point (7) is set to 3-8cm.
7. The directly welded MZI sensor of any of the claims 1-5, characterized in that the distance between the centre of said beam splitting coupling point (4) and the centre of said beam combining coupling point (7) is set to 5cm.
8. A method of making a directly fused MZI sensor according to any of claims 1-7, comprising the steps of:
step S1: intercepting two sections of single-mode fibers, marking equal-length distances in the middle of the two sections of single-mode fibers respectively, and removing coating layers at the marked positions;
step S2: simultaneously placing two sections of single-mode optical fibers on a welding machine, and disposing the same end mark at the center of the welding machine for welding treatment to form the beam splitting coupling point (4)/the beam combining coupling point (7);
step S3: and (3) moving the two sections of single-mode fibers, and disposing the other end mark at the center of a welding machine for welding treatment to form the beam combination coupling point (7)/the beam splitting coupling point (4).
9. The method according to claim 8, wherein in the step S3, the two single-mode fibers are simultaneously stretched before the other end mark is disposed at the center of the fusion splicer for fusion splicing.
10. The method according to claim 8 or 9, wherein specific parameters of the welding process in steps S2 and S3 are: the manual mode was used to discharge three times with a discharge intensity of 250J.
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