Hollow-core microstructure optical fiber welding method

Abstract

The invention relates to a hollow-core microstructure optical fiber welding method, which comprises the following steps of: 1, firstly, stripping coating layers at to-be-welded ends of two sections of optical fibers to form bare optical fiber ends, and cleaning the bare optical fiber ends; cutting the end face of the bare fiber; 2, clamping the bare optical fiber ends of the two sections of optical fibers processed in the step 1 on an optical fiber clamp of a fusion splicer, and coaxially aligning the bare optical fiber ends; the welding machine is arranged in the sealing cover; 3, aiming at the condition that the two sections of optical fibers are hollow-core micro-structure optical fibers, installing inflation valves at the external non-processing ends of the two sections of optical fibers; only one section of optical fiber is a hollow-core microstructure optical fiber, and only an inflation valve needs to be installed at the non-processing end of the hollow-core microstructure optical fiber. 4, pre-inflation is carried out, wherein the sealing cover is inflated, and the hollow-core microstructure optical fiber is inflated; and 5, after pre-inflation is completed, a welding machine is started, the two sections of optical fibers are welded, and micro-pores are filled with trace inert gas in the melting heating process so as to keep the micro-pores not collapsed. The welding power of the optical fiber can be improved, and the air holes can be prevented from collapsing.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber gyroscope manufacturing technology, and in particular to a kind of hollow microstructure optical fiber fusion method. BACKGROUND

[0002] Optical fiber gyroscope uses optical fiber as sensing medium to sense optical Sagnac effect to realize angular rate measurement, and is widely used in various types of inertial autonomous navigation systems such as land, sea, air and space. Hollow microstructure optical fiber efficiently confines light in air core for transmission, greatly reduces the influence of environment on light wave such as heat and magnetism, and has large parameter design freedom, which can realize high birefringence and low bending loss, and plays an important role in improving the performance of optical fiber gyroscope. However, the thin-walled structure of the air hole in the microstructure optical fiber is prone to collapse during heating, and the optical and mechanical properties are easily affected. In order to prevent the microstructure optical fiber from collapsing after fusion, the fusion power is usually reduced to process, so that the fusion point tensile strength is too small, and the fusion point is easy to break. Especially in the fusion splicing of microstructure optical fiber and traditional polarization maintaining optical fiber, the problem is more difficult, which makes it difficult to be applied in practice. How to ensure the fusion quality and small and convenient splicing point of microstructure optical fiber for application in optical fiber gyroscope is one of the main technical problems to be solved in replacing traditional fiber with microstructure optical fiber. SUMMARY

[0003] The present application proposes a kind of hollow microstructure optical fiber fusion method which can improve the fusion power of optical fiber and prevent air hole from collapsing.

[0004] The above-mentioned object of the present application is realized by the following technical scheme:

[0005] A kind of hollow microstructure optical fiber fusion method, comprising the following steps:

[0006] Step 1, first, remove the coating layer of the two optical fiber ends to be fused to form bare optical fiber ends, and clean the bare optical fiber ends with alcohol; then cut the bare optical fiber end face with an optical fiber cutter;

[0007] Step 2, clamp the bare optical fiber ends of the two optical fibers treated in step 1 on the optical fiber clamp of the fusion machine, so that the bare optical fiber ends of the two optical fibers are coaxially aligned; wherein the fusion machine is placed in a sealed cover, and an air inlet and an air outlet are provided on the two side walls of the sealed cover for introducing inert gas into the sealed cover, and optical fiber outlets are provided on the two opposite side walls of the sealed cover for the untreated ends of the two optical fibers to pass out respectively;

[0008] Step 3, for the case that both of the two optical fibers are hollow microstructure optical fibers, install an air charging valve on the untreated end of each of the two optical fibers; for the case that only one of the two optical fibers is a hollow microstructure optical fiber, only install an air charging valve on the untreated end of the hollow microstructure optical fiber;

[0009] Step 4, pre-inflation is carried out, including inflating into the sealed cover and inflating into the hollow microstructure optical fiber;

[0010] Step 5, after the pre-inflation is completed, the fusion machine is opened, the two optical fibers are fused, and a trace of inert gas is filled into the micro hole during the fusion heating process, so that the micro hole is not collapsed.

[0011] Moreover, in step 1, the cutting angle is less than 1°.

[0012] Moreover, in step 2, the hygroscopic cotton is also attached to the inner wall of the upper cover of the fusion machine, which is used to remove the water vapor and alcohol residues in the micro hole of the optical fiber caused by hygroscopicity and alcohol cleaning, so as to realize the dryness of the fusion air.

[0013] Moreover, in step 4, the dry inert gas is filled into the sealed cover through the gas inlet interface on the sealed cover, and the gas is discharged through the gas outlet interface. The gas inlet interface is connected with the inflation pipe and is sealed. The gas outlet hole is a self-discharge type. During the inflation, the pressure is increased, the gas valve installed on the gas outlet interface is opened, and the inflation is carried out for 5-10 minutes. The inert gas is filled into the optical fiber micro hole of the hollow microstructure optical fiber through the inflation valve, and the pressure in the air hole is kept consistent. The inflation process is 1-2 minutes.

[0014] Moreover, in step 5, the inflation is carried out by slowly injecting the gas and gradually increasing the air volume, so as to keep the stability of the optical fiber.

[0015] The present application has the advantages and positive effects that:

[0016] 1. After the to-be-fused end of the optical fiber is treated and fixed, the optical fiber micro hole of the hollow microstructure optical fiber is pre-inflated to remove impurities, so as to provide a dry and impurity-free fusion environment for the subsequent fusion, which is beneficial to guarantee the quality of the subsequent fusion.

[0017] 2. In the process of fusing the two optical fibers, the gas is filled into the micro hole of the hollow microstructure optical fiber, and the amount of the gas is reasonably controlled, so as to improve the structural strength of the hollow microstructure optical fiber in the fusion process, thereby avoiding the use of the power reduction mode for fusion, so as to guarantee the fusion point tensile strength after fusion, and also avoid the problem of air hole collapse, and greatly improve the fusion forming quality of the hollow microstructure optical fiber. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the reference diagram for implementing the hollow microstructure optical fiber fusion method of the present application;

[0019] Figure 2 is the air charge amount change diagram during the fusion process of the hollow microstructure optical fiber of the present application;

[0020] Figure 3is a reference diagram of hollow microstructure optical fiber welded by using the prior art method;

[0021] Figure 4 is a reference diagram of hollow microstructure optical fiber welded by using the method of the present application. DETAILED DESCRIPTION

[0022] The structure of the present application will be further described below in conjunction with the accompanying drawings and by way of examples. It should be noted that the examples are descriptive rather than restrictive.

[0023] The present application is directed to the problem that micro-holes are prone to collapse when microstructure optical fibers are fused, and proposes a method for welding hollow microstructure optical fibers, the invention point of which is that, in the process of welding two optical fibers, effective supporting force is provided to the air holes by inflating the micro-holes of the microstructure optical fibers, so as to prevent the air holes from collapsing and achieve high-strength welding of the microstructure optical fibers. Specifically, the method comprises the following steps:

[0024] Step 1. First, remove the coating layer at the to-be-welded end of the two optical fibers to form bare optical fiber ends, and clean the bare optical fiber ends with alcohol; then cut the end faces of the bare optical fiber ends with an optical fiber cutter, and the cutting angle is preferably less than 1°.

[0025] Step 2. Clamping the bare optical fiber ends of the two optical fibers treated in step 1 on the optical fiber clamps of a welding machine, so that the bare optical fiber ends of the two optical fibers are coaxially aligned; wherein the welding machine is placed in a sealed cover, and an air inlet and an air outlet are respectively arranged on the two side walls of the sealed cover for introducing inert gas into the sealed cover, and optical fiber outlets are arranged on the two opposite side walls of the sealed cover for the untreated ends of the two optical fibers to pass through respectively.

[0026] In addition, the inner wall of the upper cover of the welding machine is also attached with moisture-absorbing cotton to remove the water vapor and alcohol residues in the inner wall of the micro-holes of the optical fibers caused by moisture absorption and alcohol cleaning, so as to ensure that the welding air is dry and the water vapor does not affect the welding quality. The upper cover of the welding machine is kept falling.

[0027] Step 3. For the case that both the two optical fibers are hollow microstructure optical fibers, an inflation valve is installed on the untreated end of each of the two optical fibers, and the inflation valve is fixed to the outer wall of the hollow microstructure optical fiber by adhesion or the like; for the case that one of the optical fibers is a hollow microstructure optical fiber and the other is a conventional optical fiber, such as a polarization maintaining optical fiber, a single-mode optical fiber, etc., only an inflation valve needs to be installed on the untreated end of the hollow microstructure optical fiber.

[0028] Step 4. Pre-inflation, including inflating the sealed cover and inflating the hollow microstructure optical fiber, specifically:

[0029] The dry inert gas (such as helium) is filled into the sealed cover through the air inlet interface on the sealed cover, and the gas is discharged through the exhaust interface. The air inlet interface is connected with the air filling pipe and is sealed, the exhaust hole is a self-exhausting type, and when the air is filled, the exhaust valve installed on the exhaust interface is opened by increasing the pressure, and the air filling time is preferably 5-10 minutes.

[0030] At the same time, the inert gas is introduced into the air hole of the hollow microstructure optical fiber through the air filling valve, the water vapor in the microstructure optical fiber hole is removed, and the pressure in the air hole is kept consistent, which provides a dry and impurity-free fusion environment for fusion, avoids the influence of impurities and water vapor on the fusion quality, and the air filling process is preferably 1-2 minutes.

[0031] Step 5, after the pre-filling is completed, the fusion machine is started, and the two optical fibers are fused. A small amount of inert gas is filled into the micro-hole during the melting and heating process to keep the micro-hole from collapsing. When filling air, the gas needs to be slowly injected and then the air volume is gradually increased to keep the optical fiber stable, so as to avoid the optical fiber from generating micro-vibration due to too fast air filling, which affects the alignment of the optical fiber during fusion. After heating is completed, the air volume is gradually reduced to ensure the stable connection of the optical fiber after fusion. As shown in the figure, the specific air filling amount and time are determined according to the specific fiber size and micro-hole parameters. Figure 2

[0032] Although the embodiments of the present application and the drawings are disclosed for the purpose of illustration, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit of the present application and the appended claims, therefore, the scope of the present application is not limited to the disclosed content of the embodiments and the drawings.​

Claims

1. A hollow core microstructure optical fiber fusion splicing method, characterized in that: The steps include: Step 1: First, strip the coating layer of the two optical fiber ends to be fused to form a bare fiber end. Clean the bare fiber end with alcohol; then use a fiber cleaver to cut the bare fiber end face; Step 2: Clamp the bare fiber ends of the two optical fibers processed in step 1 onto the optical fiber clamp of the fusion splicer so that the bare fiber ends of the two optical fibers are coaxially aligned; wherein the fusion splicer is placed in a sealed cover, and an air inlet interface and an exhaust interface are respectively provided on the side walls of the sealed cover for introducing an inert gas into the sealed cover, and optical fiber lead-out ports are provided on the two opposite side walls of the sealed cover for the unprocessed ends of the two optical fibers to pass through in a sealed manner; Step 3: If both optical fibers are hollow-core microstructured optical fibers, install an inflation valve on the unprocessed ends of both optical fibers. If only one optical fiber is hollow-core microstructured optical fibers, install an inflation valve only on the unprocessed end of the hollow-core microstructured optical fiber. Step 4, performing pre-inflation, including inflating air into the sealing cover and inflating air into the hollow-core microstructure optical fiber; Step 5: After the pre-inflation is completed, the fusion splicer is turned on to fuse the two optical fibers. During the melting and heating process, a small amount of inert gas is filled into the micropores to prevent the micropores from collapsing.

2. The hollow-core microstructure optical fiber fusion splicing method according to claim 1, wherein: In step 1, the cutting angle is less than 1°.

3. The hollow-core microstructure optical fiber fusion splicing method according to claim 1, wherein: In step 2, moisture-absorbing cotton is attached to the inner wall of the upper cover of the fusion splicer to remove moisture and alcohol residue on the inner wall of the optical fiber micropores caused by hygroscopicity and alcohol cleaning, thereby achieving dry fusion air.

4. The hollow-core microstructure optical fiber fusion splicing method according to claim 1, wherein: In step 4, dry inert gas is filled into the sealing cover through the air inlet interface on the sealing cover, and the gas is discharged through the exhaust interface. The air inlet interface is connected with an inflation tube and is sealed. The exhaust hole is self-exhausting. When inflating, the pressure increases and the exhaust valve installed on the exhaust interface is opened. Inflate for 5-10 minutes; inert gas is introduced into the optical fiber micropores of the hollow-core microstructure optical fiber through the inflation valve, and the pressure in the air hole is kept consistent. The inflation process is 1-2 minutes.

5. The hollow-core microstructure optical fiber fusion splicing method according to claim 1, wherein: In step 5, during inflation, the gas is slowly injected and then the ventilation volume is gradually increased to maintain the stability of the optical fiber.

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