CN116735597A - Method for online detection and feedback of growth defects of sapphire optical fiber - Google Patents
Method for online detection and feedback of growth defects of sapphire optical fiber Download PDFInfo
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- CN116735597A CN116735597A CN202310547934.6A CN202310547934A CN116735597A CN 116735597 A CN116735597 A CN 116735597A CN 202310547934 A CN202310547934 A CN 202310547934A CN 116735597 A CN116735597 A CN 116735597A
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 202
- 229910052594 sapphire Inorganic materials 0.000 title claims abstract description 156
- 239000010980 sapphire Substances 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000001514 detection method Methods 0.000 title claims abstract description 33
- 230000009643 growth defect Effects 0.000 title claims abstract description 11
- 239000013078 crystal Substances 0.000 claims abstract description 76
- 238000012360 testing method Methods 0.000 claims abstract description 70
- 230000007547 defect Effects 0.000 claims abstract description 34
- 230000003287 optical effect Effects 0.000 claims abstract description 27
- 238000002360 preparation method Methods 0.000 claims abstract description 13
- 239000000835 fiber Substances 0.000 claims description 22
- 238000002844 melting Methods 0.000 claims description 11
- 230000008018 melting Effects 0.000 claims description 11
- 238000005498 polishing Methods 0.000 claims description 10
- 238000011084 recovery Methods 0.000 claims description 9
- 238000009826 distribution Methods 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 5
- 238000005253 cladding Methods 0.000 claims description 4
- 230000008878 coupling Effects 0.000 claims description 4
- 238000010168 coupling process Methods 0.000 claims description 4
- 238000005859 coupling reaction Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 4
- 238000003466 welding Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 abstract description 2
- 238000011161 development Methods 0.000 abstract description 2
- 239000007787 solid Substances 0.000 abstract description 2
- 238000011897 real-time detection Methods 0.000 description 6
- 239000010453 quartz Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000005231 Edge Defined Film Fed Growth Methods 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
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- 238000001914 filtration Methods 0.000 description 1
- 239000010437 gem Substances 0.000 description 1
- 229910001751 gemstone Inorganic materials 0.000 description 1
- 238000004093 laser heating Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- NJPPVKZQTLUDBO-UHFFFAOYSA-N novaluron Chemical compound C1=C(Cl)C(OC(F)(F)C(OC(F)(F)F)F)=CC=C1NC(=O)NC(=O)C1=C(F)C=CC=C1F NJPPVKZQTLUDBO-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
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- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/02—Testing optical properties
- G01M11/0242—Testing optical properties by measuring geometrical properties or aberrations
- G01M11/0278—Detecting defects of the object to be tested, e.g. scratches or dust
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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
- G02B6/25—Preparing the ends of light guides for coupling, e.g. cutting
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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
- G02B6/26—Optical coupling means
- G02B6/262—Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
Abstract
The invention discloses a method for online detection and feedback of growth defects of a sapphire optical fiber, which is characterized in that through the optical path matching design of the length of a target to be detected, the back scattering signal inside the sapphire optical fiber in the growth process is detected in real time by skillfully utilizing a sapphire optical fiber seed crystal with a truncated cone-shaped end part as a connecting device, and information such as internal defects, non-uniformity and the like is obtained, so that accurate quantitative data are provided for the preparation process and subsequent application of the sapphire optical fiber. The novel application of the optical fiber white light interference distributed test is realized, and a solid foundation is laid for the technical development of the sapphire optical fiber.
Description
Technical field:
the invention relates to a method for online detection and feedback of growth defects of a sapphire optical fiber, and belongs to the field of optical fiber testing.
Background
The sapphire optical fiber is an excellent high-temperature resistant waveguide, the melting point of the sapphire optical fiber is as high as 2043 ℃, the sapphire optical fiber has good high-temperature resistant performance, and the sapphire optical fiber has excellent light transmission performance in the ultraviolet to mid-infrared band, so that the sapphire optical fiber has unique advantages in high-temperature sensing application. Meanwhile, because of its high laser damage threshold, sapphire optical fibers are also widely used in high power laser devices. However, due to internal defects, non-uniformity, bubbles, and fluctuation of fiber diameter, etc., generated during the growth of the single crystal, the sapphire fiber transmission loss increases, and the optical performance deteriorates, which is unfavorable for signal reception and demodulation of the high temperature sensor.
The growth conditions of the sapphire fiber determine the quality of the fiber. Currently, commercial sapphire fibers are mostly manufactured using a laser heated susceptor method (LHPG method). In sapphire crystal growth, the main types of defects include non-uniform areas of growth and bubbles, and the presence of defects in the crystal can greatly affect the optical and mechanical properties of the sapphire fiber. (Wang D, hou W, na L I, et al, defects and Optical Property of Single-crystal Sapphire Fibers Grown by Edge-defined Film-fed growth method [ J ]]Journal ofInorganic Materials,2020, 35 (9): 573.). When the LHPG method is used for preparing the sapphire optical fiber, factors such as the feeding rate of a source rod and the moving rate of a seed crystal, the power stability of a laser heating light source, the focal position and the like can directly influence the crystal growth quality of the sapphire optical fiber (Rey-GarcI a F,R,Angurel LA,et al.Laser floating zone growth:Overview,singular materials,broad applications,and future perspectives[J]crystal 2020, 11 (1): 38. Defect detection of sapphire fibers is commonly performed using direct observation with an optical microscope or scanning electron microscope (Liu B, yu Y, bera S, et al Studiy ofmolten zone profile and defect formation during laser heated pedestal growth [ C]Air bubbles are detected by means of machine vision and image recognition methods (Yang X, qiao T, zhang H, et al research on image recognition and detection method ofsapphire bubbles [ J ])// Micro-and Nanotechnology Sensors, systems, and Applications XI.SPIE,2019, 10982:418-426.)]Journal ofInstrumentation,2019, 14 (12): P12013.) the above detection methods are generally only applicable to the detection of finished sapphire crystals. Growth on sapphire fiberThe control system often needs to adopt a high-speed camera to collect images of the diameter of the sapphire optical fiber and feed the images back to the growth control system so as to reduce the size fluctuation of the growth of the sapphire optical fiber, but the method cannot detect the internal defects of the sapphire optical fiber in real time. By means of the distributed optical fiber waveguide detection mode, abnormal reflection signals caused by internal bubbles in the grown sapphire optical fiber, internal defects such as a monocrystalline growth uneven area and the like can be detected and fed back in real time, monocrystalline growth conditions can be adjusted and optimized in time, growth quality and preparation efficiency of the sapphire optical fiber are improved finally, raw material waste is avoided, and cost is saved.
Disclosure of Invention
The invention aims to improve the growth quality and efficiency of a sapphire optical fiber, and provides an on-line detection and feedback method for the growth defect of the sapphire optical fiber; the invention uses the optical fiber white light interference distributed testing device to realize the real-time detection and feedback of the growth defect of the sapphire optical fiber, and feeds the defect signals, positions and other information measured by the optical fiber white light interference distributed testing device back to the sapphire optical fiber growth preparation system to assist in optimizing the growth process parameters.
The purpose of the invention is realized in the following way:
the on-line detection and feedback method for sapphire optical fiber growth defect includes feeding back the defect signal and position information measured by the optical fiber white light interference distributed test device to the sapphire optical fiber growth preparation system for auxiliary optimization of growth technological parameters, and includes the following steps:
step one, designing a matching optical fiber length in an optical fiber white light interference distributed test device according to the length of a sapphire optical fiber expected to grow to form an optical fiber white light interference distributed test device 9 with a matching target to be measured; the measuring arm of the optical fiber white light interference distributed testing device 9 is additionally provided with a circulator, and the light attenuator 7 and the light filter 8 are recycled, so that the intensity of the back scattered or reflected light can be conveniently adjusted, and the interference light can be conveniently filtered;
polishing the upper end surface of the sapphire optical fiber seed crystal 1 into a round table 2 according to the size of a single-mode optical fiber 6 at a test end opening of the optical fiber white light interference distributed test device 9, polishing, and making the diameter of the sapphire optical fiber seed crystal 1 different in actual growth preparation according to different target diameters of the prepared sapphire optical fibers; the diameter of the circular section at the upper part of the circular table 2 is smaller than or equal to the diameter of the cladding of the single-mode optical fiber 6 and is larger than or equal to the diameter of the fiber core of the single-mode optical fiber 6 so as to increase the optical coupling efficiency, restrict the optical transmission mode and enhance the receiving of the reflected optical signal;
welding the round table 2 and the single-mode fiber 6 together, and fixing the sapphire optical fiber seed crystal 1 on a clamp of a heating base;
starting an optical fiber white light interference distributed testing device 9, pre-testing the sapphire optical fiber seed crystal 1 in an initial state, and calibrating the optical path position of the sapphire optical fiber seed crystal 1 in the initial state;
step five, starting CO used for heating in the growth process of the sapphire optical fiber 2 A laser light source 5 for gradually raising CO 2 The laser power, the recovery light attenuator 7 and the filter 8 are regulated, so that the recovery power of the detection signal light is moderate, and the high signal-to-noise ratio of the detection signal of the optical fiber white light interference distributed testing device is ensured;
step six, after a melting area 4 at the upper part of the sapphire crystal source rod 3 is stable, the lower end of the sapphire optical fiber seed crystal 1 sinks into a melting growth area at the top of the sapphire crystal source rod 3 and is lifted upwards at a certain lifting speed, and meanwhile, the sapphire crystal source rod is fed upwards at a certain speed; the sapphire optical fiber starts to grow, the optical fiber white light interference distributed testing device 9 is formally utilized for testing, and the real-time data processing result is combined, so that the defect distribution in the growth process of the sapphire optical fiber is detected online;
step seven, in the growth stage of the sapphire optical fiber in the step six, according to the feedback of the defect distribution on-line detection result of the optical fiber white light interference distributed test device 9, the feeding rate of the source rod, the movement rate of the seed crystal and the CO are real-time carried out 2 Fine tuning of growth process parameters such as laser power and the like; after obtaining the variable parameter with the least sapphire defect, keeping the variable parameter unchanged in the subsequent growth process until a sapphire optical fiber is producedLong completion.
Compared with the prior art, the invention has the beneficial effects that:
(1) The optical fiber distributed on-line detection method for the sapphire optical fiber in the growth preparation process is provided for the first time, the quality of the sapphire optical fiber can be detected, and meanwhile, the preparation process of the sapphire optical fiber can be quantitatively improved according to the feedback of real-time detection signals;
(2) The novel sapphire optical fiber seed crystal is in a truncated cone shape, is used as a connecting device of a single-mode optical fiber and a sapphire optical fiber to be tested, solves the problem of unmatched core diameters, and can not influence the growth preparation flow of the traditional sapphire;
(3) By utilizing the performance advantages of the optical fiber white light interference distributed testing device, the high spatial resolution test of the internal defects of the sapphire optical fiber is effectively realized, and an important reference is provided for parameter setting in the growth process of the sapphire optical fiber.
(4) The defect type of the sapphire optical fiber, such as bubbles, uneven growth areas of crystals and the like, can be judged by analyzing real-time detection signals of the optical fiber white light interference distributed test device, and finally the defect type is fed back to a sapphire optical fiber growth preparation system to optimize growth process parameters, such as the pulling speed of sapphire optical fiber seed crystals, the feeding speed of sapphire crystal source rods and CO in real time 2 Focus and power stability of the laser, etc.
(5) The invention has important effect on optimizing the growth process parameters of the sapphire optical fiber and improving the growth quality of the sapphire optical fiber, and simultaneously, the real-time detection and feedback of the defects achieve the purpose of timely adjusting the optimized growth parameters, thereby effectively reducing the defective rate and saving the raw materials and the cost.
Drawings
FIG. 1 is a schematic view of the polishing shape of the top end face of a sapphire optical fiber seed crystal according to the present invention;
FIG. 2 is a schematic diagram of a real-time detection device for growth defects of sapphire optical fibers according to the present invention;
FIG. 3 is a schematic diagram of typical defect types and distributed test signals for a sapphire fiber;
FIG. 4 is a flow chart of real-time detection of growth defects and feedback control of growth parameters of a sapphire optical fiber according to the present invention.
The device comprises a sapphire optical fiber seed crystal 1, a sapphire crystal source rod 3, a melting area 4, a CO2 laser light source 5, a single-mode optical fiber 6 and a measuring end interface of an optical fiber white light interference distributed testing device 9, wherein the sapphire optical fiber seed crystal 2 is the upper end part of the sapphire optical fiber seed crystal polished into a truncated cone shape; and 7 is an optical attenuator, 8 is a filter, 9 is an optical fiber white light interference distributed test device, and 10 is a sapphire optical fiber.
Detailed Description
The invention is further described with reference to the accompanying drawings:
a method for online detection and feedback of sapphire optical fiber growth defects comprises the following steps:
the first step: and designing the matching length of the optical fibers in the optical fiber distributed interferometer according to the length of the sapphire optical fibers expected to grow, and forming the optical fiber white light interference distributed testing device with the matching target to be measured. And a circulator, a recovery light attenuator and a light filter are additionally arranged on a measuring arm of the optical fiber white light interference distributed testing device, so that the intensity of back scattered or reflected light can be conveniently adjusted, and interference light can be conveniently filtered.
And a second step of: polishing and preparing a round table-shaped sapphire optical fiber seed crystal according to the interface optical fiber size of the test end of the optical fiber white light interference distributed test device, and polishing the polished sapphire optical fiber seed crystal. The diameter of the sapphire optical fiber seed crystal is different according to the target diameter of the prepared sapphire optical fiber. The diameter of the circular section of the upper part of the circular table at the top of the seed crystal is smaller than or equal to the diameter of the quartz optical fiber cladding of the testing end of the optical fiber white light interference distributed testing device and is larger than or equal to the diameter of the quartz optical fiber core of the testing end of the optical fiber distributed measuring instrument, so that the optical coupling efficiency is increased, the optical transmission mode is restrained, and the receiving of the reflected optical signal is enhanced.
And a third step of: and (3) welding the upper bottom surface of the truncated cone-shaped sapphire optical fiber seed crystal obtained in the step two with a test end interface optical fiber of the optical fiber white light interference distributed test device, and fixing the sapphire optical fiber seed crystal on a clamp of a heating base.
Fourth step: starting the optical fiber white light interference distributed testing device, pre-testing the sapphire optical fiber seed crystal in the initial state, and calibrating the optical path position of the sapphire optical fiber seed crystal in the initial state.
Fifth step: CO for heating during start-up of sapphire fiber growth 2 Laser, gradually rising CO 2 And the laser power is regulated, and a recovery light attenuator of the optical fiber white light interference distributed test device is regulated, so that the recovery power of the detection signal light is moderate, and the high signal-to-noise ratio of the detection signal of the optical fiber white light interference distributed test device is ensured.
Sixth step: continuing to raise CO 2 The power of the laser enables the top end of the sapphire crystal source rod to form a stable melting area, the lower end of the sapphire optical fiber seed crystal is sunk into a melting growth area at the top of the sapphire crystal source rod and is pulled upwards at a certain pulling speed, and meanwhile, the sapphire crystal source rod is fed upwards at a proper speed. After meeting the requirements of the growth of the sapphire optical fiber, formally utilizing the optical fiber white light interference distributed testing device to test, and combining with the real-time data processing result, completing the online detection of the defect distribution in the growth process of the sapphire optical fiber.
Seventh step: in the initial stage of the sapphire optical fiber growth process in the step six, the feeding rate of the source rod, the movement rate of the seed crystal and the CO are respectively finely adjusted 2 And D, obtaining variable parameters with the least sapphire defects according to the online detection result of the defect distribution in the step six, and keeping the variable parameters unchanged in the subsequent growth process until the growth of one sapphire optical fiber is completed.
In view of the low coherence characteristic of the broad spectrum white light source, the optical paths of the measuring arm and the reference arm need to be strictly matched, so that the length interval of the optical fiber to be measured needs to be matched with the corresponding optical fiber length and the scanning interval of the scanning reflector. In addition, during the growth process of the precious stone optical fiber, a great amount of heat and light radiation are released along with the melting of the crystal material by the high-power laser, so that the filtering and attenuation of the recovered light are necessary, the optical fiber white light interference distributed test device is protected, and the signal detection capability of the device is improved.
The lower bottom surface of the round table is the same as the sapphire optical fiber seed crystal in size, and the diameter of the upper bottom surface of the round table is smaller than or equal to the size of the interface optical fiber of the test end interface of the optical fiber white light interference distributed test device. Because the optical fibers in the optical fiber white light interference distributed testing device all adopt single-mode optical fibers, the seed crystal is designed into a round table shape, the optical fiber white light interference distributed testing device can be ensured to be suitable for on-line detection of the sapphire optical fibers with any size, and the influence of the problem of mismatch of core diameters is weakened.
The optical path position of the seed crystal of the sapphire optical fiber in the initial state is calibrated, and the purpose is to accurately position the sapphire optical fiber grown subsequently by taking the seed crystal as a reference.
(1) First, according to the length of the sapphire fiber expected to grow, the length of the matching fiber in the fiber distributed tester is designed to form the fiber white light interference distributed tester 9 to be measured by the matching target. And a circulator is additionally arranged on a measuring arm of the optical fiber white light interference distributed testing device 9, and the light attenuator 7 and the light filter 8 are recycled, so that the intensity of back scattered or reflected light can be conveniently adjusted, and interference light can be conveniently filtered.
(2) And (3) polishing the upper end surface of the sapphire optical fiber seed crystal 1 into a round table shape 2 according to the size of a test interface optical fiber 6 of the optical fiber white light interference distributed test device 9, and polishing. The diameter of the sapphire optical fiber seed crystal 1 is different in actual growth preparation according to the target diameter of the prepared sapphire optical fiber. The diameter of the circular section of the upper part of the circular table 2 at the top of the seed crystal is smaller than or equal to the diameter of the cladding of the quartz optical fiber 6 at the test end of the optical fiber white light interference distributed test device and is larger than or equal to the diameter of the fiber core of the quartz optical fiber 6 at the test end of the optical fiber distributed measurement instrument, so that the optical coupling efficiency is increased, the optical transmission mode is restrained, and the receiving of the reflected optical signal is enhanced.
(3) The obtained upper bottom surface 2 of the truncated cone-shaped sapphire optical fiber seed crystal is welded with the interface optical fiber 6 at the test end of the optical fiber white light interference distributed test device, and the sapphire optical fiber seed crystal 1 is fixed on a clamp of a heating base.
(4) And starting the optical fiber white light interference distributed testing device 9, pre-testing the sapphire optical fiber seed crystal 1 in the initial state, and calibrating the optical path position of the sapphire optical fiber seed crystal 1 in the initial state.
(5) CO for heating during start-up of sapphire fiber growth 2 A laser light source 5 for gradually raising CO 2 The laser power, the recovery light attenuator 7 and the filter 8 are regulated, so that the recovery power of the detection signal light is moderate, and the high signal-to-noise ratio of the detection signal of the optical fiber white light interference distributed testing device is ensured.
(6) After the stable melting zone 4 is formed at the top end of the sapphire crystal source rod, the lower end of the sapphire optical fiber seed crystal is sunk into the melting growth zone at the top of the sapphire crystal source rod and is lifted upwards at a certain lifting speed, and meanwhile, the sapphire crystal source rod is fed upwards at a certain speed. The sapphire optical fiber starts to grow, the optical fiber white light interference distributed testing device is formally utilized for testing, and the defect distribution on-line detection in the growth process of the sapphire optical fiber is realized by combining the real-time data processing result.
(7) In the growth stage of the sapphire optical fiber in the step six, feeding back the feeding rate of the source rod, the moving rate of the seed crystal and CO in real time according to the feedback of the defect distribution on-line detection result of the optical fiber white light interference distributed test device 2 Fine tuning of growth process parameters such as laser power and the like; and after the variable parameters with the least sapphire defects are obtained, keeping the variable parameters unchanged in the subsequent growth process until the growth of one sapphire optical fiber is completed.
Application example 1: when the lifting speed of the sapphire optical fiber seed crystal is too high, bubbles are generated in the growing sapphire optical fiber, and strong reflection of light is generated at the bubbles, so that the optical fiber distributed measuring instrument can measure sharp abrupt peaks of reflected signals, and the generation positions of the bubbles in the sapphire optical fiber can be positioned according to the positions of scanning optical paths, as shown in fig. 3. After a sharp reflection signal peak is observed, the pulling speed of the seed crystal is finely adjusted in real time, so that the generation of bubbles in the sapphire optical fiber can be reduced, the growth parameters are optimized, and the further waste of raw materials in the growth process is avoided.
Application example 2: when the feeding speed of the source rod is too high or the pulling speed of the seed crystal is too low, a densely packed region for crystal growth can occur during the growth of the sapphire optical fiber, so that fluctuation of the density refractive index is caused. This partially non-uniform growth region is represented in the measurement signal of the fiber optic distributed meter as an overall elevation of the reflected signal over an optical path length comparable to the length of the region, as shown in fig. 3. At the moment, the feeding speed of the source rod is reduced slightly in real time or the pulling speed of the seed crystal is increased by fine adjustment properly, so that the sapphire crystal grows uniformly.
Meanwhile, the method is also suitable for defect detection of the sapphire optical fiber finished product. The sapphire optical fiber seed crystal can be replaced by the prepared sapphire optical fiber, one end of the sapphire is polished in the same way as the mode of fig. 1, and is connected with the optical fiber distributed measuring instrument, so that the internal defect of a finished product of the sapphire optical fiber can be detected, and the part with the least defect can be selected for use according to the detection information in the use of the sapphire optical fiber, such as the application to manufacturing of a sapphire optical fiber grating high-temperature you sensor or a fabry-perot interferometer high-temperature strain/temperature sensor.
Aiming at the problem that defects are easy to occur in the existing sapphire optical fiber growth process, the invention provides a distributed online detection method for the sapphire optical fiber growth process based on an optical fiber white light interference distributed test device. The optical path matching design of the target length to be detected is adopted, the sapphire optical fiber seed crystal with the truncated cone-shaped end part is ingeniously utilized as a connecting device, the back scattering signal inside the sapphire optical fiber in the growth process is detected in real time, information such as internal defects and non-uniformity is obtained, and accurate quantitative data are provided for the preparation process and subsequent application of the sapphire optical fiber. The novel application of the optical fiber white light interference distributed test is realized, and a solid foundation is laid for the technical development of the sapphire optical fiber.
Claims (1)
1. The on-line detection and feedback method for the growth defect of the sapphire optical fiber is characterized in that information such as defect signals and positions measured by an optical fiber white light interference distributed testing device is fed back to a sapphire optical fiber growth preparation system, and growth process parameters are optimized in an auxiliary mode, and the method specifically comprises the following steps:
step one, designing a matching optical fiber length in an optical fiber white light interference distributed test device according to the length of a sapphire optical fiber expected to grow to form an optical fiber white light interference distributed test device (9) with a matching target to be measured; the measuring arm of the optical fiber white light interference distributed testing device (9) is additionally provided with a circulator, and the light attenuator (7) and the light filter (8) are recycled, so that the intensity of the back scattered or reflected light can be conveniently adjusted, and the interference light can be conveniently filtered;
polishing the upper end face of the sapphire optical fiber seed crystal (1) into a round table (2) according to the size of a single-mode optical fiber (6) at a test end interface of the optical fiber white light interference distributed test device (9), polishing, and carrying out polishing treatment, wherein the diameters of the sapphire optical fiber seed crystal (1) are different in actual growth preparation according to different target diameters of the prepared sapphire optical fibers; the diameter of the circular section at the upper part of the circular table (2) is smaller than or equal to the diameter of the cladding of the single-mode optical fiber (6) and is larger than or equal to the diameter of the fiber core of the single-mode optical fiber (6), so that the optical coupling efficiency is increased, the optical transmission mode is restrained, and the receiving of a reflected optical signal is enhanced;
welding the round table (2) and the single-mode fiber (6) together, and fixing the sapphire fiber seed crystal (1) on a clamp of a heating base;
starting an optical fiber white light interference distributed testing device (9), pre-testing the sapphire optical fiber seed crystal (1) in an initial state, and calibrating the optical path position of the sapphire optical fiber seed crystal (1) in the initial state;
step five, starting CO used for heating in the growth process of the sapphire optical fiber 2 A laser light source (5) for gradually increasing CO 2 The laser power, the recovery light attenuator (7) and the filter (8) are regulated, so that the recovery power of the detection signal light is moderate, and the high signal-to-noise ratio of the detection signal of the optical fiber white light interference distributed test device is ensured;
step six, after a melting area (4) at the upper part of the sapphire crystal source rod (3) is stable, the lower end of the sapphire optical fiber seed crystal (1) sinks into a melting growth area at the top of the sapphire crystal source rod (3) and is lifted upwards at a certain lifting speed, and meanwhile, the sapphire crystal source rod is fed upwards at a certain speed; the sapphire optical fiber starts to grow, the optical fiber white light interference distributed testing device (9) is formally used for testing, and the real-time data processing result is combined, so that the defect distribution in the growth process of the sapphire optical fiber is detected on line;
step seven, in the growth stage of the sapphire optical fiber in the step six, feeding back the feeding rate of the source rod, the moving rate of the seed crystal and CO in real time according to the feedback of the defect distribution on-line detection result of the optical fiber white light interference distributed testing device (9) 2 Fine tuning of growth process parameters such as laser power and the like; and after the variable parameters with the least sapphire defects are obtained, keeping the variable parameters unchanged in the subsequent growth process until the growth of one sapphire optical fiber is completed.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117468083A (en) * | 2023-12-27 | 2024-01-30 | 浙江晶盛机电股份有限公司 | Control method and device for seed crystal lowering process, crystal growth furnace system and computer equipment |
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2023
- 2023-05-16 CN CN202310547934.6A patent/CN116735597A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117468083A (en) * | 2023-12-27 | 2024-01-30 | 浙江晶盛机电股份有限公司 | Control method and device for seed crystal lowering process, crystal growth furnace system and computer equipment |
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