CN116256861B - Optical fiber F-P cavity temperature sensor and packaging protection structure - Google Patents
Optical fiber F-P cavity temperature sensor and packaging protection structure Download PDFInfo
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- CN116256861B CN116256861B CN202310511847.5A CN202310511847A CN116256861B CN 116256861 B CN116256861 B CN 116256861B CN 202310511847 A CN202310511847 A CN 202310511847A CN 116256861 B CN116256861 B CN 116256861B
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 320
- 238000004806 packaging method and process Methods 0.000 title claims abstract description 31
- CFOAUMXQOCBWNJ-UHFFFAOYSA-N [B].[Si] Chemical compound [B].[Si] CFOAUMXQOCBWNJ-UHFFFAOYSA-N 0.000 claims abstract description 62
- 229910052796 boron Inorganic materials 0.000 claims abstract description 59
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 58
- 239000010703 silicon Substances 0.000 claims abstract description 58
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 58
- 230000008018 melting Effects 0.000 claims abstract description 47
- 238000002844 melting Methods 0.000 claims abstract description 47
- 239000000428 dust Substances 0.000 claims abstract description 32
- 239000000835 fiber Substances 0.000 claims description 108
- 230000002093 peripheral effect Effects 0.000 claims description 22
- 239000000565 sealant Substances 0.000 claims description 14
- 230000000903 blocking effect Effects 0.000 claims description 13
- 239000010453 quartz Substances 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 229910052594 sapphire Inorganic materials 0.000 claims description 11
- 239000010980 sapphire Substances 0.000 claims description 11
- 239000004519 grease Substances 0.000 claims description 8
- 229910001338 liquidmetal Inorganic materials 0.000 claims description 8
- 229920001296 polysiloxane Polymers 0.000 claims description 8
- 238000005538 encapsulation Methods 0.000 claims description 4
- 230000035945 sensitivity Effects 0.000 description 13
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- 229910052751 metal Inorganic materials 0.000 description 6
- 239000011247 coating layer Substances 0.000 description 5
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- 238000010438 heat treatment Methods 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 238000002310 reflectometry Methods 0.000 description 2
- 239000013535 sea water Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
-
- 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
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The application relates to the technical field of temperature sensors, in particular to an optical fiber F-P cavity temperature sensor and a packaging protection structure. An optical fiber F-P cavity temperature sensor comprises a capillary tube with a first melting point; an optical fiber part, wherein a bare optical fiber with one end part exposed is inserted into the capillary tube, and the bare optical fiber has a second melting point; the high-boron silicon tube is a first section of high-boron silicon, a second section of high-boron silicon and a third section of high-boron silicon, the high-boron silicon tube has a third melting point, the first section of high-boron silicon and the third section of high-boron silicon are both in cylindrical structures, and the second section of high-boron silicon is in an arc structure; the first section of high-boron silicon is sleeved at the front end part of the bare optical fiber and is used for collimating the bare optical fiber; the second section of high boron silicon is arranged in the middle of the bare optical fiber, and forms an accommodating space for accommodating dust with the capillary tube, so that the dust reduces friction on the outer wall of the bare optical fiber; the third section of high boron silicon is sleeved at the rear end part of the bare optical fiber, and the high boron silicon is melted to form a connecting point for fixing the bare optical fiber in the capillary; the third melting point is less than the first and second melting points, respectively.
Description
Technical Field
The application relates to the technical field of temperature sensors, in particular to an optical fiber F-P cavity temperature sensor and a packaging protection structure.
Background
The temperature is an extremely important parameter in heavy engineering perception systems such as intelligent ocean, transparent ocean and the like, and along with global climate warming, the change of the temperature of the sea water can influence sound wave transmission, generate optical turbulence effect and the like, and the temperature compensation correction is needed for various underwater monitoring data, thereby playing an important role in ocean economic development, construction and the like. Because of the physical characteristics of the seawater, the temperature is relatively stable, and if the temperature change in the ocean is to be measured, the temperature resolution of the sensor is required to be high. In addition, in the seismic observation, temperature is used as a scalar quantity, so that analysis and processing are easier, and the possibility of earthquake occurrence is increasingly focused by monitoring the ground temperature change and pushing back the dynamic change of the underground stress. Because the ground temperature field is very stable, the deeper the monitoring depth is in a certain depth range, the higher the judgment accuracy is, and the higher the requirements on the resolution ratio and the temperature range of the sensor are.
The fiber Fabry-Perot cavity temperature sensor (called as a fiber F-P cavity for short) has the advantages of small volume, high sensitivity, high temperature and pressure resistance, corrosion resistance, electromagnetic interference resistance and the like, is widely applied to the measurement of sea temperature and ground temperature, and particularly, the extrinsic fiber F-P cavity is most widely used. The structure of the extrinsic optical fiber F-P cavity is that two sections of optical fibers are jointly placed in a section of collimating capillary, and the capillary can collimate the two sections of optical fibers. The capillary tube is made of silicon, high boron silicon, metal and the like, and the fixing of the two sections of optical fibers and the collimating capillary tube can be realized by epoxy resin glue, anodic bonding, high-temperature hot melting and other methods. In the process of forming fixation in the optical fiber inserting capillary, because the clearance between the two is very small, the friction is easy to attach, dust exists in the capillary, and in the process of inserting the optical fiber into the capillary, the dust can be brought into the capillary, the dust existing between the inner wall of the capillary and the outer peripheral wall of the optical fiber can increase the friction force between the outer peripheral wall of the optical fiber and the inner wall of the capillary, and when the temperature changes, the dust can obstruct the relative movement of the optical fiber and the capillary, so that the performance of the optical fiber F-P cavity sensor is affected.
Accordingly, there is a need for a structure that avoids or reduces dust from affecting the performance of fiber optic Fabry-Perot cavity temperature sensors.
Disclosure of Invention
The application provides an optical fiber F-P cavity temperature sensor and a packaging protection structure, which solve the problem that dust affects the performance of the optical fiber F-P cavity temperature sensor.
A first aspect of the present application provides an optical fiber F-P cavity temperature sensor comprising:
a capillary having a first melting point;
an optical fiber part, wherein a bare optical fiber with one end part exposed is inserted into the capillary, and the bare optical fiber has a second melting point;
the high-boron silicon tube is sequentially divided into a first section of high-boron silicon, a second section of high-boron silicon and a third section of high-boron silicon along the length direction of the high-boron silicon tube, and the high-boron silicon tube has a third melting point, wherein the first section of high-boron silicon and the third section of high-boron silicon are both in cylindrical structures, and the second section of high-boron silicon is in an arc structure; wherein,,
the first section of high-boron silicon is sleeved at the front end part of the bare optical fiber so that the bare optical fiber and the axis of the capillary are coaxial and used for collimating the bare optical fiber;
the second section of high boron silicon is arranged in the middle of the bare optical fiber, and forms an accommodating space for accommodating dust with the capillary tube, so that the dust reduces friction on the outer wall of the bare optical fiber;
the third section of high-boron silicon is sleeved at the rear end part of the bare optical fiber, and under the condition that part of the high-boron silicon of the third section of high-boron silicon is in a molten form, the molten high-boron silicon forms a connection point for fixing the bare optical fiber in the capillary;
the third melting point is less than the first melting point and the second melting point, respectively.
In one embodiment, the optical fiber portion includes a first optical fiber and a second optical fiber, the first optical fiber has a first bare fiber, the second optical fiber has a second bare fiber, and the outer peripheral walls of the first and second bare fibers are both wrapped with the high borosilicate tube; wherein,,
the first optical fiber and the second optical fiber are separated at two ends of the capillary, the first bare optical fiber and the second bare optical fiber are respectively arranged in the capillary, a first section of high boron silicon on the first bare optical fiber is adjacent to a first section of high boron silicon on the second bare optical fiber, and the first bare optical fiber and the second bare optical fiber are supported, so that the first bare optical fiber and the second bare optical fiber are coaxial.
In one embodiment, the optical fiber unit further includes a third optical fiber, and the optical fiber unit includes a first optical fiber; the first optical fiber has a first bare optical fiber;
the third optical fiber and the first bare optical fiber are respectively arranged inside the two ends of the capillary tube; wherein,,
the high-boron silicon tube is wrapped on the peripheral wall of the first bare optical fiber, a first section of high-boron silicon on the first bare optical fiber is used for adjusting the first bare optical fiber so that the first bare optical fiber and the third optical fiber are coaxial, and the third optical fiber is fixed in the capillary tube through the high-boron silicon.
In one mode of practice, the capillary tube is a sapphire material, the first melting point is 2053 ℃, and the thermal expansion coefficient alpha 1 =8.8×10 -6 The internal diameter is phi 0.3+/-0.05 mm at the temperature of/DEG C;
the bare optical fiber of the optical fiber part is made of quartz material, the second melting point is 1780 ℃, and the thermal expansion coefficient alpha 2 =0.35×10 -6 At the temperature of/DEG C, the outer diameter is phi 125+/-0.05 mu m;
the third melting point of the high boron silicon tube is 820 ℃, and the thermal expansion coefficient alpha 3 =3.3×10 -6 And the outer diameter is phi 0.3+/-0.05 mm.
In one embodiment, a distance between an outer peripheral wall of the optical fiber portion and an inner peripheral wall of the capillary is 80 to 150 μm; the wall thickness of the high boron silicon tube is 2-10 mu m.
The second aspect of the application provides a packaging protection structure of an optical fiber F-P cavity temperature sensor, which comprises a protection tube, a pressure-bearing tube, a packaging base, a pressure relief capillary tube, sealant and the optical fiber F-P cavity temperature sensor;
one end of the protection tube is sealed, and the other end of the protection tube is connected with the packaging base;
the optical fiber F-P cavity temperature sensor is arranged in the pressure-bearing tube, and part of the optical fiber F-P cavity temperature sensor protrudes out of the opening end;
the pressure relief capillary is arranged in the packaging base;
the optical fiber part of the optical fiber F-P cavity temperature sensor passes through the packaging base and extends out of the packaging base;
the part, protruding out of the opening end, of the optical fiber F-P cavity temperature sensor, the pressure relief capillary tube and the opening end of the pressure bearing tube are fixed through the sealant.
In one implementation, the outer peripheral wall of the protection tube is provided with a plurality of grooves axially arranged along the protection tube, and a plurality of grooves are arranged at intervals along the outer peripheral wall of the protection tube.
In one mode of implementation, the pressure-bearing pipe is filled with liquid metal heat-conducting silicone grease.
In one implementation manner, the packaging base is provided with a through hole coaxial with the axis of the packaging base, one end of the packaging base embedded with the pressure-bearing pipe is provided with a stepped hole, and the other end of the packaging base is provided with a plugging hole and a plugging piece;
wherein, the stepped hole and the plugging hole are coaxial with the through hole;
the stepped hole is filled with the sealant, so that the opening end of the pressure-bearing pipe is fixed in the packaging base; the blocking piece is blocked in the blocking hole, so that the optical fiber is fixed in the through hole of the packaging base through the blocking hole.
In one mode of implementation, the optical fiber plugging device further comprises an armored optical cable, wherein the armored optical cable is wrapped on the peripheral wall of the optical fiber part, and one end of the armored optical cable is abutted on the bottom wall of the plugging hole.
The beneficial effects of the application are that:
the application provides an optic fibre F-P chamber temperature sensor and encapsulation protection architecture, inserts the naked bare fiber of back optic fibre portion in the capillary, and the cover is equipped with high borosilicate pipe on bare fiber, and wherein, high borosilicate pipe divide into three sections, is first section high borosilicate, second section high borosilicate and the high borosilicate of third section in proper order, and first section high borosilicate and the high borosilicate of third section are tubular structure, and the high borosilicate of second section is curved structure. The first section of high-boron silicon is sleeved at the end part of the bare optical fiber so as to enable the bare optical fiber to overlap with the axis of the capillary tube and be used for collimating the bare optical fiber; the second section of high boron silicon is arranged in the middle of the bare optical fiber, and forms an accommodating space for accommodating dust with the capillary tube, so that the dust reduces friction on the outer wall of the bare optical fiber; and the third section of high-boron silicon is arranged at the rear part of the bare optical fiber, and the molten high-boron silicon forms a connecting point for fixing the bare optical fiber in the capillary under the condition that part of the high-boron silicon of the third section of high-boron silicon is in a molten state. Wherein the capillary tube has a first melting point, the bare fiber of the fiber portion has a second melting point, the high borosilicate tube has a third melting point, and the melting points of the third melting point are the first melting point and the second melting point, respectively. Thus, in the case where the third-stage high boron silicon is melted, part of the third-stage high boron silicon is melted between the bare fiber and the capillary, so that a connection point is formed, and the bare fiber and the capillary are not affected by the melting of the third melting point. The dust between the capillary tube and the bare optical fiber is ensured to be in the accommodating space through the structure, and the friction of the dust to the outer wall of the bare optical fiber can be avoided or reduced due to the large space in the accommodating space, so that the performance of the optical fiber F-P cavity temperature sensor is ensured. In addition, the bare optical fiber is raised by the high boron silicon at the first end, so that the bare optical fiber is coaxial with the axis of the capillary, and the optical fiber F-P cavity temperature sensor has the advantages of high sensitivity, high resolution, high precision, large temperature range and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a conventional fiber F-P cavity temperature sensor;
FIG. 2 is a schematic diagram of a structure in which a first optical fiber and a second optical fiber are inserted into a capillary tube of an optical fiber F-P cavity temperature sensor according to the present application;
FIG. 3 is a schematic view of a structure in which an optical fiber portion and a third optical fiber of an optical fiber F-P cavity temperature sensor of the present application are respectively inserted into a capillary;
FIG. 4 is a schematic diagram showing a lambda of an optical fiber F-P cavity temperature sensor according to the present application as a wavelength value corresponding to a certain peak in an optical fiber F-P cavity spectrum;
FIG. 5 is a schematic diagram of a temperature calibration curve of each temperature point fiber F-P cavity length of a fiber F-P cavity temperature sensor according to the present application, wherein the temperature calibration curve is plotted on the ordinate;
FIG. 6 is a schematic diagram of a package protection structure of an optical fiber F-P cavity temperature sensor according to the present application;
fig. 7 is a schematic view of the external structure of a protection tube of an optical fiber F-P cavity temperature sensor according to the present application.
Reference numerals:
1-a capillary; 2-dust; 3-optical fiber; 31-an incident optical fiber; a 32-reflective optical fiber; 4-an optical fiber section; 41-a first bare fiber; 42-a second bare fiber; 43-optical fiber coating layer; 5-high boron silicon tube; 51-first stage high boron silicon; 52-second stage high boron silicon; 53-third section high boron silicon; 6-a third optical fiber; 7-connection point;
100-protecting tube; 101-grooves; 110-a pressure-bearing pipe; 111-liquid metal heat conducting silicone grease; 112-step hole; 1121-macropores; 1122-small holes; 120-packaging the base; 121-a through hole; 122-step holes; 123-plugging the hole; 124-closure; 130-a pressure relief capillary; 140, sealant; 150-an optical fiber F-P cavity temperature sensor; 160-armored fiber optic cable.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Under the condition that two end optical fibers 3 of the optical fiber F-P cavity temperature sensor are placed into a section of collimating capillary 1 together, the capillary 1 is mostly made of materials such as silicon, high boron silicon or metal, and the fixing of the optical fibers 3 and the capillary 1 is realized through methods such as epoxy resin glue, anodic bonding or high temperature melting, as shown in fig. 1, the capillary 1 is made of metal materials, and the incident optical fibers 31 and the reflecting optical fibers 32 of the capillary 1 and the optical fibers 3 are fixed through a bonding mode (the incident optical fibers 31 and the reflecting optical fibers 32 are bare optical fibers), so that the optical fiber F-P temperature sensor is manufactured, and the problems of small temperature range, poor precision and poor stability of the optical fiber F-P temperature sensor are easily caused due to the fact that the metal materials are unstable and the gluing mode is easy to generate thermal mismatch, creep and the like. In addition, the capillary 1 is made of high-boron silicon, the optical fiber F-P cavity temperature sensor is made in a high-temperature melting capillary 1 mode, the sensitivity of the optical fiber F-P cavity temperature sensor made of high-boron silicon is low, the larger the gap between the bare optical fiber and the wall of the capillary 1 is, the thicker the adhesive layer is, the more serious the creep and thermal mismatch problems are, the larger the gap is, and the problem that the fusion point of high-temperature melting is not easy to form is easily caused. In addition, the larger the gap between the bare fiber and the inner wall of the capillary tube 1 is, the more serious the transverse dislocation and inclination of the end face of the bare fiber are, and the worse the spectral quality of the F-P cavity of the optical fiber is. Therefore, the inner diameter of the capillary 1 is generally phi 126-phi 130 μm, the outer diameter phi 125 μm of the bare fiber, and the gap between the bare fiber and the wall of the capillary 1 is only 0.5-2.5 μm, under the size, impurities such as dust 2 (the outer diameter of the dust 2 is about 0.5-20 μm) exist in the capillary 1 and on the surface of the bare fiber during the penetration of the bare fiber into the capillary 1, and the dust 2 is filled in the gap between the bare fiber and the wall of the capillary 1, so that the friction force on the surface of the bare fiber is increased, when the external temperature of the optical fiber F-P cavity temperature sensing changes, the relative movement of the bare fiber and the capillary 1 is prevented, the bare fiber is inclined after the adhesion solidification or the high-temperature hot melting, the positive pressure on the wall of the capillary 1 is increased, the phenomenon is aggravated, and the temperature sensing performance of the F-P cavity of the optical fiber is seriously affected.
In addition, in order to ensure the performance of the optical fiber F-P cavity temperature sensor, the gap between the capillary 1 and the bare optical fiber is required to be as small as possible, generally 0.5-5 μm, so that the inner wall of the capillary 1 is easy to be attached to the bare optical fiber, when the temperature changes, friction is generated when the capillary 1 and the bare optical fiber relatively move, and the performance of the sensor is influenced, in this case, if dust 2 impurities (such as PM 2.5-5) exist in the gap, the phenomenon is aggravated, and the influence on the performance of the sensor is aggravated.
For the above reasons, when the optical fiber F-P cavity temperature sensor is manufactured, the gap between the capillary 1 and the bare optical fiber needs to be increased, after the gap is increased, the connection point is not easy to form, the bare optical fiber is not collimated, the expansion coefficients of the capillary 1 and the bare optical fiber are large (the difference is 16 times), and when the temperature change is large, the connection point is easy to be thermally mismatched, cracked and even separated, so that the performance of the sensor is affected.
In view of this, this application adopts high borosilicate capillary, and its coefficient of thermal expansion is located between the two, and coefficient of thermal expansion smooth transition, the tie point can not thermal mismatch, and the special structure of high borosilicate capillary, size can increase the clearance between capillary 1 and the bare fiber that sapphire material constitutes again simultaneously, and plays the collimation effect to the bare fiber, have improved the performance of sensor greatly.
In view of this, the present application proposes an optical fiber F-P cavity temperature sensor.
An optical fiber F-P cavity temperature sensor comprises a capillary tube 1, an optical fiber part 4 and a high boron silicon tube 5.
Wherein the capillary tube 1 is a tubular structure having a first melting point capable of collimating two lengths of bare optical fiber inserted therein, the capillary tube 1 may be formed of a sapphire material, for example, having a first melting point of about 2053 ℃ and a coefficient of thermal expansion α 1 =8.8×10 -6 At the temperature of/DEG C, the inner diameter is phi 0.3 plus 0.05mm, the outer diameter phi 0.4-phi 1mm, and the outer diameter phi 0.5mm of the capillary tube 1 is preferred. The capillary 1 made of the sapphire material has higher sensitivity to temperature, so that the capillary 1 made of the sapphire material can improve the resolution of the optical fiber F-P cavity temperature sensor.
The optical fiber portion 4 includes a bare fiber and an optical fiber coating layer 43 coated outside the bare fiber, wherein a part of the bare fiber protrudes from the optical fiber coating layer 43, that is, the optical fiber coating layer 43 is peeled off from the bare fiber to form a bare fiber protruding from the optical fiber coating layer 43, so that the bare fiber of the protruding portion can be assembled with the capillary tube 1. Part of the bare optical fiber of the optical fiber part 4 is exposed outside the optical fiber part 4 so that the exposed part can be inserted into the capillary tube 1, and the optical fiber coating 43 is contacted with the high boron silicon tube 5, so that the strength of the bare optical fiber is increased, and the bare optical fiber is prevented from being bent and broken. The bare optical fiber has a second melting point, which may be, for example, a quartz material, with a thermal expansion coefficient alpha of about 1780 DEG C 2 =0.35×10-6/°c, an outer diameter Φ125 μm, end faces were flattened with a cutter or polished, and reflectivity was about 4%.
As shown in fig. 2, the high borosilicate tube 5 is divided into a first segment of high borosilicate 51, a second segment of high borosilicate 52, and a third segment of high borosilicate 53 in this order along the length thereof, the high borosilicate tube 5 having a third melting point, and the high borosilicate tube 5 having a third melting point of about 820 c thermal expansion coefficient α 3 =3.3×10 -6 At the temperature of °c, the inner diameter Φ126 to Φ130 μm and the outer diameter Φ0.3mm, the inner diameter of the high boron silicon tube 5 is preferably Φ130 μm.
Specifically, the first section of high boron silicon 51 and the third section of high boron silicon 53 are both cylindrical structures, and the sections of the first section of high boron silicon 51 and the third section of high boron silicon 53 are circular rings; the second section of high boron silicon 52 is of an arc structure, and the section of the second section of high boron silicon 52 is of a semicircular ring shape.
The first section of high boron silicon 51 is sleeved on the front end part of the bare optical fiber so that the bare optical fiber is coaxial with the axis of the capillary 1 and is used for collimating the bare optical fiber.
The second section of high boron silicon 52 is arranged in the middle of the bare optical fiber, and forms an accommodating space with the capillary 1 for accommodating dust 2, so that the dust 2 reduces friction on the outer wall of the bare optical fiber.
The third section of high boron silicon 53 is sleeved on the rear end part of the bare optical fiber, and when part of the high boron silicon of the third section of high boron silicon 53 is in a molten state, the molten high boron silicon forms a connection point 7 for fixing the bare optical fiber in the capillary 1.
Under the condition that two bare fibers are relatively inserted into the capillary tube 1 and the two bare fibers are a first bare fiber and a second bare fiber, the first section of high boron silicon 51 is sleeved at the front end part of the first bare fiber, the front end surface of the first bare fiber protrudes out of the first section of high boron silicon 51, the protruding distance is 2-5mm, preferably, the protruding distance is 3mm, so that the first section of high boron silicon 51 is prevented from contacting with the end surface of the second bare fiber, the end surface of the second bare fiber is prevented from being damaged, the sensitivity is influenced, in addition, under the condition that the first bare fiber protrudes out of the first section of high boron silicon 51, the first bare fiber is adjusted in the capillary tube 1 in a small range, and the fault tolerance in the assembly process can be improved. In addition, the first length of high borosilicate 51 is capable of collimating and centering the first bare fiber.
The second section high boron silicon 52 arc structure can make the interval distance between the first bare fiber which is not wrapped by the second section high boron silicon 52 and the capillary 1 be greater than the size of the dust 2, so that the dust 2 can move in the accommodating space to avoid or reduce the damage to the surface of the first bare fiber caused by impurities such as the dust 2, that is, when the temperature of the outside changes, the first bare fiber is affected by the outside temperature, and when the first bare fiber deforms, the dust 2 cannot rub with the outer wall of the first bare fiber along with the deformation of the first bare fiber, thereby reducing or avoiding the surface damage of the first bare fiber.
The distance between the connecting position of the third section high boron silicon 53 and the second section high boron silicon 52 and the end face of the capillary tube 1 is more than or equal to 5mm, so that the melting point position can be conveniently determined according to the length of the third section high boron silicon 53, and the capillary tube 1 is heated, so that the third section high boron silicon 53 is partially melted to form the connecting point 7. With the connection point 7, the stability and reliability between the capillary 1 and the bare fiber are increased.
As shown in fig. 2, in one embodiment, the optical fiber portion 4 may include a first optical fiber, which may be a single-mode incident optical fiber, and a second optical fiber, which may be a single-mode reflective optical fiber. The first optical fiber has a first bare fiber 41 and the second optical fiber has a second bare fiber 42. The first optical fiber and the second optical fiber are respectively arranged at two ends of the capillary tube 1, so that the first bare optical fiber 41 and the second bare optical fiber 42 are respectively inserted into the capillary tube 1 from two ends of the capillary tube 1, and the first bare optical fiber 41 and the second bare optical fiber 42 form a transmission channel for transmitting temperature signals in the capillary tube 1.
Specifically, the first optical fiber and the second optical fiber are separated at two ends of the capillary 1, the first bare optical fiber 41 and the second bare optical fiber 42 are respectively arranged in the capillary 1, the first section of high boron silicon 51 on the first bare optical fiber 41 is adjacent to the first section of high boron silicon 51 on the second bare optical fiber 42, the first bare optical fiber 41 and the second bare optical fiber 42 are supported so as to enable the first bare optical fiber 41 and the second bare optical fiber 42 to be coaxial, that is, the first section of high boron silicon 51 sleeved by the first bare optical fiber 41 and the first section of high boron silicon 51 sleeved by the second bare optical fiber 42 are respectively aligned with the first bare optical fiber 41 and the second bare optical fiber 42, so that the first bare optical fiber 41 and the second bare optical fiber 42 in the capillary 1 can be aligned and centered, the temperature signal transmission is facilitated, and the sensitivity is improved. That is, the two end surfaces of the F-P cavity can be parallel and collimated by using the first section of high-boron silicon 51 arranged on the first bare optical fiber 41 and the second bare optical fiber 42, so that the spectrum quality of the F-P cavity is high and the sensor performance is good.
In this length, the first and second bare fibers 41 and 42 may be inserted into the capillary 1 by a distance of about 5 to 10cm, and the front ends of the first and second bare fibers 41 and 42 may sag due to gravity, which may cause misalignment of the end surfaces of the first and second bare fibers 41 and 42, and may result in poor collimation effect. When the front ends of the first bare fiber 41 and the second bare fiber 42 are respectively provided with the first section of high borosilicate 51, the first section of high borosilicate 51 can form an effective support for the front ends of the first bare fiber 41 and the second bare fiber 42, that is, the wall thickness of the first section of high borosilicate 51 is utilized to form a support between the bare fiber and the inner wall of the capillary 1, so as to raise the first bare fiber 41 and the second bare fiber 42, increase the distance between the first bare fiber 41 and the second bare fiber 42 and the capillary 1, and avoid that the front ends of the first bare fiber 41 and the second bare fiber 42 drop on the wall of the capillary 1 due to gravity, so that the front end faces of the first bare fiber 41 and the second bare fiber 42 can be coaxial, and the effect of collimating the first bare fiber 41 and the second bare fiber 42 is achieved, thereby improving the sensitivity of temperature signal transmission. In addition, the first bare fiber 41 and the second bare fiber 42 drop, which increases the friction between the dust 2 and the outer walls of the first bare fiber 41 and the second bare fiber 42, further affecting the sensitivity of the temperature signal.
As shown in fig. 3, in one embodiment, a third optical fiber 6 is further included, and illustratively, the third optical fiber 6 may be a reflective optical fiber, and the third optical fiber 6 may be a quartz column or a large core optical fiber, with an outer diameter Φ200μm, an end face adopting a polishing treatment, and a reflectivity of about 4%. A tube of high boron silicon is spaced between the third optical fiber 6 and the capillary 1 to form a junction 7 when the tube of high boron silicon is heated, illustratively a coefficient of thermal expansion alpha 3 =3.3×10 -6 At the temperature of/DEG C, the inner diameter phi 205 mu m, the outer diameter phi 0.3mm and the length 3mm.
The optical fiber section 4 includes a first optical fiber having a first bare fiber 41 as an incident optical fiber. Illustratively, the high borosilicate tube 5 disposed between the first bare fiber 41 and the capillary 1 has a coefficient of thermal expansion alpha 3 =3.3×10 -6 At the temperature of/DEG C, the inner diameter phi 126-130 mu m and the outer diameter phi 0.3mm. The high borosilicate tube 5 sleeved by the first bare fiber 41 has the same structure as the high borosilicate tube 5 described above, and will not be described here again.
The third optical fiber 6 is inserted from one end of the capillary 1, and the first bare fiber 41 of the first optical fiber is inserted from the other end of the capillary 1, so that the third optical fiber 6 and the first bare fiber 41 form a transmission channel for transmitting a temperature signal in the capillary 1.
Wherein the first bare fiber 41 is coated with the high boron silicon tube 5 on the outer peripheral wall of the first bare fiber 41 as mentioned in the previous embodiment, the first section of high boron silicon 51 on the first bare fiber 41 is used for adjusting the first bare fiber 41 so that the first bare fiber 41 is coaxial with the third fiber 6, and the third fiber 6 is fixed in the capillary tube 1 by the high boron silicon. That is, the high borosilicate tube 5 can fix not only the first bare fiber 41 in the capillary 1, but also ensure that the first bare fiber 41 is coaxial with the third fiber 6.
In one embodiment, the distance between the outer peripheral wall of the optical fiber portion 4 and the inner peripheral wall of the capillary tube 1 is 80 to 150 μm, and preferably, the distance between the outer peripheral wall of the optical fiber portion 4 and the inner peripheral wall of the capillary tube 1 is 100 μm. The wall thickness of the high borosilicate tube 5 is 2 to 10 μm, and preferably the wall thickness of the high borosilicate tube 5 is 5 μm. With such a dimension, the fitting between the optical fiber portion 4 and the capillary 1 can be ensured, and the stabilizing effect of the optical fiber F-P cavity temperature sensor can be improved.
In summary, in the optical fiber F-P cavity temperature sensor provided by the present application, when the bare optical fiber of the optical fiber portion 4 is inserted into the capillary tube 1, oxyhydrogen flame, electrode heating and CO can be adopted 2 And the third section of high-boron silicon 53 is heated in a non-gelling packaging mode such as high-temperature hot melting of a laser, so that the third section of high-boron silicon 53 is melted to form a connecting point 7. The melting point of the high boron silicon is lower than that of quartz and sapphire, so that the bare optical fiber of the optical fiber part 4 is not damaged while the connection point 7 is formed, the damage is avoided, the quality of the light beam is prevented from being influenced, the expansion coefficient of the high boron silicon is between that of the quartz and the sapphire, the gradient of the difference of the thermal expansion coefficients is reduced, the stability of the formed fusion point is high, the problems of thermal mismatch, creep and the like are not easy to occur, the optical fiber F-P cavity temperature sensor can realize the monitoring of a large temperature range of 0 ℃ to 150 ℃, and meanwhile, the stability, the precision and the like of the sensor are improved.
Under the condition that the optical fiber part 4 comprises an incident bare optical fiber and a reflecting bare optical fiber, the gap between the incident and reflecting bare optical fibers at two ends of the high-boron silicon tube 5 and the capillary tube 1 is more than 87 mu m (the incident and reflecting bare optical fibers are positioned in the area of the second section of high-boron silicon 52), the gap is far larger than the outer diameter of dust 2 particles and impurities, and the length of the high-boron silicon tube 5 along the bare optical fiber is only a few mm and is far smaller than the conventional structure by tens of mm, so that the probability of friction resistance generated by the dust 2 and impurities when the temperature changes is greatly reduced, the friction resistance can be almost ignored, and the performances of the optical fiber F-P cavity temperature sensor, such as precision, repeatability and the like, are greatly improved.
Next, the optical fiber portion 4 includes an incident bare fiber, and in the case where the reflective fiber is a quartz column or a large core fiber: using oxyhydrogen flame, electrode heating and CO 2 The non-gel packaging modes such as high-temperature hot melting of the laser and the like form connection points 7 in the two ends of the capillary tube 1, and the high-boron silicon tube on the quartz column side is completely melted to form the connection points 7. Similarly, since the melting point of high boron silicon is lower than that of quartz and sapphire, the fusion point is formed without exposing the optical fiberThe fiber is damaged, so that the damage is avoided to influence the quality of the light beam; the high boron silicon thermal expansion coefficient is between the quartz and the sapphire, the gradient of the thermal expansion coefficient difference is reduced, the formed fusion point is high in stability, the problems of thermal mismatch, creep and the like are not easy to occur, the sensor can realize monitoring in a large temperature range of 0-150 ℃, and meanwhile, the stability, the precision and the like of the sensor are improved. In addition, in fig. 3, the gap between the incident optical fiber and the capillary 1 is more than 87 μm, the gap between the quartz column or the large-core optical fiber is more than 50 μm, the outer diameter of dust 2 particles and impurities is far greater than that of the high-boron silicon tube 5, and the length of the high-boron silicon tube along the bare optical fiber is only a few mm and is far less than that of the conventional structure by tens of mm, so that the probability of friction resistance generated by the dust 2 and impurities when the temperature changes is greatly reduced, the friction resistance is almost negligible, and the performances of the sensor such as precision and repeatability are greatly improved.
As shown in fig. 2 and 3, an optical fiber F-P cavity temperature sensor of the present application is described below as an example for obtaining better temperature resolution of the structure of the present application:
temperature sensitivity of fiber F-P cavity temperature sensor: when the external environment changes delta T, the cavity length d of the F-P cavity of the optical fiber changes due to the fact that the expansion coefficients of the sapphire pipe (capillary 1) and the bare optical fiber are different according to the definition of the thermal expansion coefficients, and the change quantity of the cavity length d of the F-P cavity of the optical fiber meets the following relation:
（1）
where Lg is the gauge length (effective length) between the two connection points 7, L if L is the effective length of the incident fiber rf Is the effective length of the reflective fiber or quartz column.
Formula (1) can be converted into:
（2）
wherein Deltad/DeltaT is the temperature sensitivity of the optical fiber F-P cavity temperature sensor, when Lg is 50mm, L if 、L rf When about 30mm is taken, the user passes by (2)And calculating to obtain the delta d/delta T which is approximately 507 nm/DEG C.
When the cavity of the F-P cavity of the optical fiber is air, the length d of the F-P cavity meets the following conditions:
（3）
as shown in FIG. 4, λ is a wavelength value corresponding to a peak in the spectrum of the F-P cavity of the optical fiber, and k is an interference order corresponding to the peak. The cavity length of the optical fiber F-P cavity is set to be 90-150 mu m, and the interference order corresponding to the wave peak value in the spectrum within the bandwidth of 1520-1570 nm is about 140. Taking the derivative of formula (3) yields:
（4）
taking the MOI SM125 model demodulator as an example, the wavelength resolution and repeatability of the demodulator can reach 0.2pm, and when the demodulator is brought into the formula (4), Δd=0.014 nm can be obtained.
Calibrating and testing the optical fiber F-P cavity temperature sensor:
the optical fiber F-P cavity temperature sensor and the high-precision thermometer (precision +/-0.01 ℃) of the Fulu gram 1502a are simultaneously placed in a constant-temperature water tank, the temperature fluctuation degree of the water tank is 0.01 ℃, the temperature is sequentially set to be 10 ℃ and 20 ℃ and … … ℃, then the temperature is reduced in the opposite direction, each temperature point is kept for 30min, the optical fiber F-P cavity temperature sensor is connected with a MOI SM125 demodulator, the cavity length value of the optical fiber F-P cavity is recorded in real time, the temperature rise and fall cavity length value of each temperature point is averaged, the temperature value monitored by the Fulu gram 1502a is taken as the horizontal coordinate, the cavity length value of the optical fiber F-P cavity of each temperature point is taken as the vertical coordinate to be used for temperature curve, and the temperature curve is subjected to linear fitting, as shown in fig. 5. In FIG. 5, the temperature sensitivity of the optical fiber F-P cavity temperature sensor can reach 486 nm/DEG C within the temperature range of 10-80 ℃ and is similar to the theoretical value of 507 nm/DEG C.
Because the temperature sensitivity delta d/delta T of the optical fiber F-P cavity temperature sensor is approximately 507 nm/DEG C, the delta T is approximately 3 multiplied by 10 -5 The temperature resolution of the optical fiber F-P cavity temperature sensor can reach3×10 -5 The temperature sensor meets the resolution requirements of temperature sensors in marine and seismic observation. Illustratively, if the demodulation algorithm of the F-P cavity length is optimized, for example, the demodulation algorithm performs averaging and other treatments, the optical fiber F-P cavity temperature sensor can achieve higher temperature resolution.
As shown in fig. 6, the present application also provides an embodiment of a package protection structure of the optical fiber F-P cavity temperature sensor, which is applied to the foregoing embodiment of the optical fiber F-P cavity temperature sensor. The packaging protection structure of the optical fiber F-P cavity temperature sensor comprises a protection tube 100, a pressure-bearing tube 110, a packaging base 120, a pressure relief capillary 130, a sealant 140 and the optical fiber F-P cavity temperature sensor 150.
As shown in fig. 6 and 7, one end of the protection tube 100 is sealed, and the other end is connected to the package base 120, and the protection tube 100 may be connected to the package base 120 by a threaded connection. Illustratively, the outer circumferential wall of the protection tube 100 is provided with a plurality of grooves 101 disposed along the axial direction of the protection tube 100, and the plurality of grooves 101 are disposed at intervals along the outer circumferential wall of the protection tube 100. The grooves 101 can serve as a guide to accelerate heat transfer in the protection tube 100.
The package base 120 may be formed of a stainless steel material.
The pressure-bearing tube 110 is disposed in the protection tube 100 along the length direction of the protection tube 100, and the protection tube 100 and the package base 120 form protection for the pressure-bearing tube 110. One end of the pressure-bearing pipe 110 is sealed to form a sealed end; the other end is an opening, an opening end is formed, the opening end is embedded into the packaging base 120, an optical fiber F-P cavity temperature sensor 150 is arranged in the pressure-bearing tube 110, and the pressure-bearing tube 110 is filled with liquid metal heat-conducting silicone grease 111; the optical fiber F-P cavity temperature sensor 150 partially protrudes from the open end for temperature signal transmission through the protruding portion. Illustratively, the pressure-bearing tube 110 may be a cold-drawn red copper pressure-bearing tube for bearing external pressure, thereby avoiding the optical fiber F-P cavity temperature sensor 150 from being subjected to external pressure, affecting sensitivity and damage. The open end of the pressure-bearing tube 110 has a stepped bore 112, with the small bore 1122 of the stepped bore 112 illustratively having a diameter of about phi 0.8-1.4 mm and the large bore 1121 having a diameter of about 2mm.
The pressure release capillary 130 is disposed in the package base 120, and one end of the pressure release capillary 130 is inserted into the large hole 1121 of the step hole 112, so that under the condition that the pressure bearing tube 110 bears a certain pressure, the liquid metal heat conduction silicone grease 111 filled in the pressure bearing tube 110 passes through the small hole 1122 of the step hole 112, enters the large hole 1121, and then enters the pressure release capillary 130 from the large hole 1121, thereby realizing pressure release of the pressure bearing tube 110 and avoiding the pressure bearing of the optical fiber F-P cavity temperature sensor 150. Preferably, pressure relief capillary 130 is constructed of a stainless steel material.
The part of the protruding opening end of the optical fiber F-P cavity temperature sensor 150, the pressure relief capillary 130 and the opening end of the pressure bearing tube 110 are fixed through the sealant 140 to form a sealing structure, and the capillary suction effect of the pressure relief capillary 130 is utilized to prevent the liquid metal heat conduction silicone grease 111 in the pressure bearing tube 110 from automatically overflowing from the pressure relief capillary 130.
The optical fiber portion 4 of the optical fiber F-P cavity temperature sensor 150 passes through the package base 120 and extends outside the package base 120 so as to transmit a temperature signal to the outside of the package base 120 through the optical fiber portion 4.
In one embodiment, the package base 120 has a through hole 121 coaxial with its axis, and the package base 120 has a stepped hole 122 at one end of the package base 120 embedded with the pressure-bearing tube 110, and a blocking hole 123 and a blocking piece 124 at the other end.
Wherein, the stepped hole 122 and the blocking hole 123 are coaxial with the through hole 121.
The stepped hole 122 is filled with a sealant 140 so that the open end of the pressure-bearing tube 110 is fixed in the package base 120. It should be noted that, the sealant 140 is a high-temperature sealant, and the high-temperature sealant is used to fix the pressure-bearing tube 110 in the stepped hole 122, and also has a sealing function, so that the protection tube 100, the pressure-bearing tube 110 and the package base 120 together form a sealed space.
The blocking member 124 is blocked in the blocking hole 123 such that the optical fiber is fixed in the through hole 121 of the package base 120 through the blocking hole 123. The plugging member 124 can fix the optical fiber to the package base 120. Illustratively, the blocking member 124 is a tapered metal ferrule, and limits the optical fiber portion 4 by utilizing the deformable property of the metal ferrule, forming a sealing structure.
In one embodiment, the optical fiber cable further comprises an armored optical cable 160, the armored optical cable 160 is wrapped on the peripheral wall of the optical fiber part 4, and one end of the armored optical cable 160 is abutted on the bottom wall of the plugging hole 123.
Wherein the armored fiber optic cable 160 passes into a central bore at the other end of the package base 120. Illustratively, the outer diameter of the armored cable 160 may be Φ1/8 inch, the optical fiber portion 4 is disposed in the armored cable 160, and the metal deformation seal is performed by the tapered metal ferrule (the sealing member 124), so that the reliability of the seal of the armored cable 160 is improved.
In summary, according to the packaging protection structure of the optical fiber F-P cavity temperature sensor provided by the application, the pressure-bearing tube 110 is protected by the protection tube 100 and the packaging base 120, and the pressure-bearing tube 110 is filled with the liquid metal heat-conducting silicone grease 111, so that the heat dissipation effect of the pressure-bearing tube 110 is improved. When the pressure-bearing pipe 110 receives a certain pressure, the liquid metal heat-conducting silicone grease 111 filled in the pressure-bearing pipe 110 can flow into the pressure-releasing capillary 130 along the step hole 112, so that the pressure in the pressure-bearing pipe 110 is relieved. The stepped hole 122 that encapsulation base 120 one end set up can conveniently be fixed pressure-bearing pipe 110 through sealant 140, and the shutoff hole 123 that the other end set up cooperates with shutoff piece 124 and realizes fixing and sealing to armoured cable 160. The structure not only can realize the protection of the optical fiber F-P cavity temperature sensor 150, but also can work and cool the optical fiber F-P cavity temperature sensor 150 so as to ensure the stability of the optical fiber F-P cavity temperature sensor 150.
The foregoing examples merely illustrate specific embodiments of the invention, which are described in greater detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (10)
1. An optical fiber F-P cavity temperature sensor, comprising:
a capillary having a first melting point;
an optical fiber part, wherein a bare optical fiber with one end exposed is inserted into the capillary, and the bare optical fiber has a second melting point;
the high-boron silicon tube is sequentially divided into a first section of high-boron silicon, a second section of high-boron silicon and a third section of high-boron silicon along the length direction of the high-boron silicon tube, and the high-boron silicon tube has a third melting point, wherein the first section of high-boron silicon and the third section of high-boron silicon are both in cylindrical structures, and the second section of high-boron silicon is in an arc structure; wherein,,
the first section of high-boron silicon is sleeved at the front end part of the bare optical fiber so that the bare optical fiber and the axis of the capillary are coaxial and used for collimating the bare optical fiber;
the second section of high boron silicon is arranged in the middle of the bare optical fiber, and forms an accommodating space for accommodating dust with the capillary tube, so that the dust reduces friction on the outer wall of the bare optical fiber;
the third section of high-boron silicon is sleeved at the rear end part of the bare optical fiber, and under the condition that part of the high-boron silicon of the third section of high-boron silicon is in a molten form, the molten high-boron silicon forms a connection point for fixing the bare optical fiber in the capillary;
the third melting point is less than the first melting point and the second melting point, respectively.
2. The optical fiber F-P cavity temperature sensor of claim 1, wherein the optical fiber portion comprises a first optical fiber and a second optical fiber, the first optical fiber having a first bare fiber, the second optical fiber having a second bare fiber, the outer peripheral walls of the first and second bare fibers each being wrapped with the high boron silicon tube; wherein,,
the first optical fiber and the second optical fiber are separated at two ends of the capillary, the first bare optical fiber and the second bare optical fiber are respectively arranged in the capillary, a first section of high boron silicon on the first bare optical fiber is adjacent to a first section of high boron silicon on the second bare optical fiber, and the first bare optical fiber and the second bare optical fiber are supported, so that the first bare optical fiber and the second bare optical fiber are coaxial.
3. The optical fiber F-P cavity temperature sensor of claim 1, further comprising a third optical fiber, and wherein the optical fiber portion comprises a first optical fiber; the first optical fiber has a first bare optical fiber;
the third optical fiber and the first bare optical fiber are respectively arranged inside the two ends of the capillary tube; wherein,,
the high-boron silicon tube is wrapped on the peripheral wall of the first bare optical fiber, a first section of high-boron silicon on the first bare optical fiber is used for adjusting the first bare optical fiber so that the first bare optical fiber and the third optical fiber are coaxial, and the third optical fiber is fixed in the capillary tube through the high-boron silicon.
4. The optical fiber F-P cavity temperature sensor according to claim 1, wherein,
the capillary is made of sapphire, the first melting point is 2053 ℃, and the thermal expansion coefficient alpha 1 =8.8×10 -6 The internal diameter is phi 0.3+/-0.05 mm at the temperature of/DEG C;
the bare optical fiber of the optical fiber part is made of quartz material, the second melting point is 1780 ℃, and the thermal expansion coefficient alpha 2 =0.35×10 -6 At the temperature of/DEG C, the outer diameter is phi 125+/-0.05 mu m;
the third melting point of the high boron silicon tube is 820 ℃, and the thermal expansion coefficient alpha 3 =3.3×10 -6 And the outer diameter is phi 0.3+/-0.05 mm.
5. The optical fiber F-P cavity temperature sensor according to claim 1, wherein a distance between an outer peripheral wall of the optical fiber portion and an inner peripheral wall of the capillary tube is 80 to 150 μm; the wall thickness of the high boron silicon tube is 2-10 mu m.
6. An encapsulation protection structure of an optical fiber F-P cavity temperature sensor, which is characterized by comprising a protection tube, a pressure-bearing tube, an encapsulation base, a pressure relief capillary tube, sealant and the optical fiber F-P cavity temperature sensor according to any one of claims 1-5;
one end of the protection tube is sealed, and the other end of the protection tube is connected with the packaging base;
the optical fiber F-P cavity temperature sensor is arranged in the pressure-bearing tube, and part of the optical fiber F-P cavity temperature sensor protrudes out of the opening end;
the pressure relief capillary is arranged in the packaging base;
the optical fiber part of the optical fiber F-P cavity temperature sensor passes through the packaging base and extends out of the packaging base;
the part, protruding out of the opening end, of the optical fiber F-P cavity temperature sensor, the pressure relief capillary tube and the opening end of the pressure bearing tube are fixed through the sealant.
7. The package protection structure of the optical fiber F-P cavity temperature sensor according to claim 6, wherein a plurality of grooves are formed in the peripheral wall of the protection tube and are arranged along the axial direction of the protection tube, and a plurality of grooves are arranged at intervals along the peripheral wall of the protection tube.
8. The package protection structure of the optical fiber F-P cavity temperature sensor of claim 6, wherein the pressure-bearing tube is filled with liquid metal heat-conducting silicone grease.
9. The package protection structure of the optical fiber F-P cavity temperature sensor according to claim 6, wherein the package base is provided with a through hole coaxial with the axis of the package base, one end of the package base embedded with the pressure-bearing tube is provided with a stepped hole, and the other end is provided with a plugging hole and a plugging piece;
wherein, the stepped hole and the plugging hole are coaxial with the through hole;
the stepped hole is filled with the sealant, so that the opening end of the pressure-bearing pipe is fixed in the packaging base; the blocking piece is blocked in the blocking hole, so that the optical fiber is fixed in the through hole of the packaging base through the blocking hole.
10. The package protection structure of the optical fiber F-P cavity temperature sensor according to claim 9, further comprising an armored cable, wherein the armored cable is wrapped on the peripheral wall of the optical fiber portion, and one end of the armored cable is abutted on the bottom wall of the plugging hole.
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