Micro-nano optical fiber finish machining method

Abstract

The invention relates to a micro-nano optical fiber finish machining method. The method comprises the following steps: preprocessing a single-mode optical fiber; fixing the single-mode optical fiber, adjusting the flow of hydrogen and oxygen to initial values, and heating the middle position for a first heating time; reducing the flow of hydrogen and oxygen, reversely stretching the optical fiber at a preset stretching speed to reach a preset stretching length, and stopping stretching; the hydrogen and oxygen flows are adjusted again, and the middle position is heated for second heating time; stopping heating and obtaining a micro-nano optical fiber with a target size, wherein the target size comprises a waist area diameter Dw, a conical transition area length Lt and a taper angle omega (z); wherein the preset stretching speed and the preset stretching length are calculated according to the waist area diameter Dw and the conical transition area length Lt. According to the method, the finish machining process of the micro-nano optical fiber is controlled in a mode of adjusting multiple variables at the same time, the product quality problem caused by a single variable is avoided, and the size and shape of the optical fiber can be accurately controlled.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano optical fiber processing and production, and in particular to a micro-nano optical fiber precision processing method. Background Art

[0002] Micro-nano optical fibers, with their unique optical properties such as low transmission loss, strong optical field confinement, large waveguide dispersion, and compatibility with standard optical fibers, have shown broad application prospects in optical communications, sensing detection, quantum optics, and other fields. However, the preparation technology of micro-nano optical fibers has long faced bottlenecks such as insufficient correlation between process parameters and structural morphology and low reproducibility, which have restricted its practical application. Currently, the mainstream preparation methods include solution pulling, electrospinning, femtosecond laser direct writing, chemical etching, and flame taper. Among them, the flame taper method has attracted much attention due to its simple process, low cost, and high uniformity of the produced optical fiber diameter. However, its core problem lies in the extensive control of process parameters and its reliance on experience.

[0003] The traditional flame taper process is usually divided into stages such as melting, stretching, and shaping. For example, Chinese invention patent publication number CN119125012A discloses a method for preparing a gas sensor, which includes: controlling the left and right motors of a fusion splicer to stretch a single-mode optical fiber until the stretched length is 100 μm; setting the discharge intensity and discharge time of the fusion splicer electrodes, and performing arc discharge on the central area where the coating is stripped to prepare two tapered straight cones; placing the straight cones in the grooves of two optical fiber clamps, with the thinnest part of the waist area aligned with the center of the hydrogen flame, keeping the straight cones in a stretched state, and fixing the single-mode optical fibers at both ends of the straight cones with magnetic attraction. However, the existing technology has the following significant drawbacks:

[0004] (1) Isolation of parameter adjustment: Existing methods mostly use single-variable adjustment (such as changing only the drawing speed or drawing length), ignoring the dynamic coupling effect of the drawing speed, drawing length, and the hydrogen / oxygen flow rate of the flame. For example, although increasing the drawing speed alone can reduce the waist diameter, it will cause the steepness of the tapered transition zone to exceed the design range, causing the risk of fiber breakage.

[0005] (2) Repeatability is difficult to guarantee: The optical fiber sizes prepared in different batches fluctuate greatly, making it difficult to meet the requirements of high-precision sensor probes.

[0006] Furthermore, controlling the hydrogen / oxygen flow rates during the flame taper process directly impacts the fiber's melting state. Existing techniques typically fix the gas flow rates or adjust them roughly based on experience, resulting in a mismatch between the heating temperature and the taper action, which can easily cause fiber burnout or morphological distortion.

[0007] Therefore, designing a micro-nano optical fiber precision processing method remains an urgent problem to be solved. Summary of the Invention

[0008] The purpose of the present invention is to provide a micro-nano optical fiber precision processing method that can accurately control the size and shape of the optical fiber, solve the problems of reliance on experience and extensive adjustment in the existing technology, improve the repeatability and stability of the micro-nano optical fiber preparation process, and improve the yield.

[0009] To achieve the above-mentioned object of the invention, the present invention provides a micro-nano optical fiber precision processing method, comprising the following steps:

[0010] Step S1, single-mode optical fiber pretreatment;

[0011] Step S2, fixing the single-mode optical fiber, adjusting the flow rates of hydrogen and oxygen to initial values, and heating the middle position for a first heating time;

[0012] Step S3, reducing the flow rate of hydrogen and oxygen, and reversely stretching the optical fiber at a preset stretching speed until it reaches a preset stretching length, and then stopping the stretching;

[0013] Step S4: adjust the flow rates of hydrogen and oxygen again and heat the middle position for a second heating time;

[0014] Step S5: Stop heating and obtain a micro-nano optical fiber of target size, wherein the target size includes the waist diameter D w , length of tapered transition zone L t and cone angle Ω(z);

[0015] The preset stretching speed and the preset stretching length are determined by the waist diameter D w , length of tapered transition zone L t Calculated, expressed as:

[0016]

[0017] Among them, t1 represents the first heating time, t2 represents the second heating time, Q1 represents the initial hydrogen flow rate in step S2, Q2 represents the initial oxygen flow rate in step S2, f1(t1, t2, Q1, Q2), f2(t1, t2, Q1, Q2), g1(t1, t2, Q1, Q2) and g2(t1, t2, Q1, Q2) represent process coefficients.

[0018] According to a technical solution of the present invention, the micro-nano optical fiber finishing method further includes:

[0019] Step S6: Measure the size of the micro-nano optical fiber with the target size obtained in step S5; based on the waist diameter D obtained by measurement w , length of tapered transition zone L t Determine the cone angle Ω(z).

[0020] According to a technical solution of the present invention, the waist diameter D w, the length of the tapered transition zone L t The relationship with the cone angle Ω(z) is expressed as:

[0021]

[0022] According to a technical solution of the present invention, the process coefficient is determined by the process factor K, which is specifically expressed as:

[0023]

[0024] Then we have:

[0025]

[0026] According to a technical solution of the present invention, in step S3, the hydrogen flow rate is reduced to 70% to 80% of the initial hydrogen flow rate; and the oxygen flow rate is reduced to 15% to 20% of the initial oxygen flow rate.

[0027] According to a technical solution of the present invention, step S1 includes:

[0028] Remove about 3-5 cm of coating from the surface of the single-mode optical fiber and wipe the surface of the single-mode optical fiber clean.

[0029] According to a technical solution of the present invention, step S2 includes:

[0030] Placing the single-mode optical fiber in the optical fiber clamps on the left and right sides of the optical fiber taper machine;

[0031] Adjust the distance between the fixtures;

[0032] The middle position of the single-mode optical fiber is heated using an oxyhydrogen flame, and the heating time is the first heating time.

[0033] According to a technical solution of the present invention, step S5 includes:

[0034] The oxyhydrogen flame gas source is turned off, and after stopping heating, the micro-nano optical fiber is kept in the fixture and naturally cooled to room temperature.

[0035] According to a technical solution of the present invention, step S6 includes:

[0036] Fix the micro-nano optical fiber on the stage, adjust the light source and magnification to clearly display the waist and transition zones, and record the actual values of the waist diameter and the length of the tapered transition zone using the microscope measurement software.

[0037] According to a technical solution of the present invention, the machining error of the waist diameter is less than 40 μm, and the length of the tapered transition zone is less than 10 μm. t The processing error is less than 0.5μm.

[0038] The beneficial effects of the present invention are:

[0039] According to one solution of the present invention, by establishing a mathematical relationship model between stretching parameters (such as stretching speed and stretching length) and micro-nano optical fiber morphology (such as waist diameter and tapered transition zone length), the finishing process of micro-nano optical fiber is controlled by adjusting multiple variables simultaneously, thereby avoiding product quality problems caused by a single variable and being able to accurately control the size and shape of the optical fiber, solving the problems of reliance on experience and extensive adjustment in the prior art.

[0040] The present invention combines the preset stretching speed, the preset stretching length, and the multi-stage precise control of the heating power and time of the flame head to ensure the controllability and repeatability of the optical fiber morphology.

[0041] Through refined regulation, the repeatability and stability of the micro-nano optical fiber preparation process have been improved, and the yield rate has been significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A flowchart schematically showing a method for fine processing of micro-nano optical fibers according to an embodiment of the present invention;

[0043] Figures 2(a), 2(b), 2(c) and 2(d) schematically illustrate the operation diagrams of each stage of the micro-nano optical fiber finishing method;

[0044] Figure 3 The figure schematically shows the test results of repeatability of micro-nano optical fiber preparation under the same parameters using the micro-nano optical fiber finishing method of the present invention. DETAILED DESCRIPTION

[0045] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0046] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0047] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0048] The micro-nano optical fiber precision processing method of the present invention realizes precise control of the size and shape of micro-nano optical fibers, solves the problems of reliance on experience and extensive adjustment in the existing technology, improves the repeatability and stability of the micro-nano optical fiber preparation process, and significantly improves the yield rate.

[0049] like Figure 1 As shown, according to one embodiment of the present invention, a micro-nano optical fiber finishing method of the present invention includes the following steps:

[0050] Preprocessing stage:

[0051] Step S1, single-mode optical fiber pretreatment;

[0052] Remove about 3-5 cm of coating from the surface of the single-mode optical fiber and wipe the surface of the single-mode optical fiber clean. In specific implementation, select a standard single-mode optical fiber (such as G652) and use optical fiber stripping pliers to strip the coating along the optical fiber axis. The stripping length is determined according to the requirements of the processing area, usually 3-5 cm. Then use a dust-free cloth dipped in a reagent (such as anhydrous ethanol) to gently wipe the surface of the optical fiber in a ventilated environment to thoroughly remove residual coating fragments, dust and oil, ensure that the exposed area of the optical fiber is clean, and provide a good processing foundation for subsequent heating and stretching.

[0053] Flame Melting Stage I:

[0054] Step S2: fixing the single-mode optical fiber, adjusting the flow rates of hydrogen and oxygen to initial values, and heating the middle position for a first heating time;

[0055] As shown in Figure 2(a), the single-mode optical fiber is placed in the optical fiber clamps on the left and right sides of the optical fiber taper machine; the middle position of the single-mode optical fiber is heated using an oxyhydrogen flame, and the heating time is the first heating time; in specific implementation, the optical fiber taper machine uses a precision model (such as XQ7140), the clamp spacing is set to 3-15cm to ensure the stretching space, the initial hydrogen flow rate is 145sccm, the oxygen flow rate is 45sccm, and the first heating time is controlled between 10-25 seconds (preferably 20 seconds). During the heating process, the flame evenly covers the area of about 2-3mm in the middle of the optical fiber, so that the optical fiber is softened to a plastic state.

[0056] By centrally heating the middle of the single-mode optical fiber and keeping the flame head and fixture stationary, the optical fiber is quickly and evenly molten, providing a good foundation for the subsequent stretching stage, ensuring the consistency of the optical fiber's molten state, and helping to improve the stability of the preparation process.

[0057] Fixture reverse tension stage II:

[0058] Step S3, reducing the flow rate of hydrogen and oxygen, and reversely stretching the optical fiber at a preset stretching speed until it reaches a preset stretching length, and then stopping the stretching;

[0059] Normally, reduce the hydrogen flow rate to 70% to 80% of the initial flow rate; reduce the oxygen flow rate to 15% to 20% of the initial flow rate;

[0060] As shown in Figure 2(b), the flow rates of hydrogen and oxygen are reduced to preset values; the single-mode optical fiber is reversely stretched at a preset stretching speed until the stretching length reaches the preset stretching length and the stretching is stopped; in specific implementation, the hydrogen flow rate is reduced from the initial value to 110 sccm, and the oxygen flow rate is reduced to 8 sccm to reduce the flame intensity and control the temperature of the heating area.

[0061] Real-time monitoring during the stretching process ensures uniform deformation of the optical fiber to form a preliminary tapered structure. This step is key to achieving precise dimensional control.

[0062] The preset stretching speed and the preset stretching length are determined by the waist diameter D w , length of tapered transition zone L t Calculated, expressed as:

[0063]

[0064] Among them, t1 represents the first heating time, t2 represents the second heating time, Q1 represents the initial hydrogen flow rate in step S2, Q2 represents the initial oxygen flow rate in step S2, f1(t1, t2, Q1, Q2), f2(t1, t2, Q1, Q2), g1(t1, t2, Q1, Q2) and g2(t1, t2, Q1, Q2) represent process coefficients.

[0065] Based on the theory of heat conduction and melt rheology, the heating time affects the degree of material melting and stress relaxation, and the gas flow rate affects the flame temperature field distribution, which together determine the deformation behavior of the optical fiber during the stretching process.

[0066] Among them, the process coefficient is determined by the process factor K, which is specifically expressed as:

[0067]

[0068] Then we have:

[0069]

[0070] The process factor K quantifies the impact of process parameters on viscosity. Heating times (primary and secondary heating times) and gas flow rates (hydrogen and oxygen) directly influence flame temperature and thermal field distribution. The primary and secondary heating times determine the melting state of the optical fiber; hydrogen and oxygen flow rates regulate flame intensity (hydrogen provides fuel, while oxygen aids combustion).

[0071] Fire head heating stage III:

[0072] Step S4, adjusting the flow rates of hydrogen and oxygen again, and heating the middle position for a second heating time;

[0073] As shown in FIG2(c), the flow rates of hydrogen and oxygen are adjusted to another preset value; the middle position of the single-mode optical fiber is heated for a second heating time;

[0074] In the third stage, the hydrogen flow rate and the oxygen flow rate need to be increased compared to the second stage. The increased hydrogen flow rate is usually 5% to 15% of the initial flow rate; the increased oxygen flow rate is usually 3% to 8% of the initial flow rate.

[0075] The hydrogen flow rate is adjusted to 120 sccm, and the oxygen flow rate is adjusted to 10 sccm, and the flame coverage range is increased to about 3-4 mm. The second heating time is set to 5-15 seconds. This heating further shapes the tapered area of the optical fiber and optimizes the uniformity of the waist diameter and the transition zone length. This step is combined with the airflow reduction in step S3 to form a unique two-stage heating process of the present invention, thereby improving processing accuracy.

[0076] Fire head out of position stage IV:

[0077] Step S5: Stop heating and obtain a micro-nano optical fiber of target size, wherein the target size includes the waist diameter D w , length of tapered transition zone L t ;

[0078] As shown in Figure 2(d), turn off the oxyhydrogen flame source, stop heating, and keep the fiber in the fixture to cool naturally for about 1-2 minutes to room temperature (about 25°C). Avoid external interference during the cooling process to prevent fiber deformation. Finally, the waist diameter D is obtained. w 1-10μm, the error is usually 40μm, the length of the tapered transition zone L t For micro-nano optical fibers with a diameter of 5-50 mm, the error is usually within 0.5 μm. This step ensures that the optical fiber has a stable shape after processing and that the dimensions meet the design requirements.

[0079] Step S6: measuring the size of the micro-nano optical fiber with the target size obtained in step S5.

[0080] The waist diameter and tapered transition zone length of the micro-nano optical fiber are measured using an optical microscope or a scanning electron microscope. In the specific implementation, a high-resolution optical microscope (such as Olympus BX51, magnification 1000 times) or SEM (such as FEIQuanta 200) is selected, the micro-nano optical fiber is fixed on the stage, the light source and magnification are adjusted to clearly display the waist and transition zone, and the D is recorded using the microscope measurement software. w and L t The actual value is measured with an accuracy of 0.01μm. The measurement results are used to verify whether the processing has reached the target size and provide data support for subsequent process optimization.

[0081] Based on the measured waist diameter D w , length of tapered transition zone L t Determine the cone angle Ω(z), waist diameter D w , the length of the tapered transition zone L t The relationship with the cone angle Ω(z) is expressed as:

[0082]

[0083] Since the direct taper angle Ω(z) is difficult and has large deviation, the length of the tapered transition zone L is used. t As the measured value, the cone angle Ω(z) is calculated, which has the advantages of high accuracy and convenient measurement.

[0084] The present invention is described in detail below based on specific examples.

[0085] Example 1

[0086] Using the above method, five single-mode optical fibers were simultaneously fine-processed according to the same parameters to produce five micro-nano optical fibers. During the fabrication process, the consistency of process parameters was strictly controlled while ensuring the stability of the experimental environment. Five sets of micro-nano optical fiber sensor probes were successively prepared. Microscopy was used to characterize the morphology and measure the dimensions of the five sensor probe samples, focusing on observing and measuring two key structural parameters: the waist diameter and the length of the tapered transition region.

[0087] As shown in Figure 2, the average waist diameter of the five MNFs is 13.552 μm, with a standard deviation of 0.43 μm. The average length of the tapered transition zone is 1599 μm, with a standard deviation of 33.96 μm. This demonstrates that the dimensional fluctuation of the micro-nano optical fibers produced using the same parameters is small, with errors within 5%, demonstrating good fabrication repeatability. This result validates the stability and reliability of the micro-nano optical fiber processing method of the present invention.

[0088] The following examples are briefly described.

[0089] Example 2

[0090] Target parameters: waist diameter 10 microns, tapered transition zone length 1200 microns;

[0091] Process steps:

[0092] 1. Pretreatment: Remove 4 cm of coating from the surface of the single-mode optical fiber, fix it to the fixture, and adjust the spacing to 8 cm;

[0093] 2. Stage I (flame melting): initial hydrogen flow rate 120 SCCM, oxygen flow rate 15 SCCM, heating time 20 seconds;

[0094] 3. Stage II (reverse stretching): hydrogen flow rate reduced to 85% of the initial value (102 SCCM), oxygen flow rate reduced to 18% of the initial value (3 SCCM), stretching speed 6 mm / min, stretching length 4 mm;

[0095] 4. Stage III (secondary heating): hydrogen flow rate 110 SCCM, oxygen flow rate 12 SCCM, heating time 15 seconds;

[0096] 5. Measurement results: The waist diameter was measured to be 10.20 μm (error +0.20 μm), and the length of the tapered transition zone was measured to be 1200.30 μm (error +0.30 μm); the standard deviations of the five batches were 0.15 μm and 0.40 μm respectively.

[0097] Example 3

[0098] Target parameters: waist diameter 15 microns, tapered transition zone length 1800 microns;

[0099] Process steps:

[0100] 1. Pretreatment: Remove 3 cm of coating from the surface of the single-mode optical fiber, fix it to the fixture, and adjust the spacing to 6 cm;

[0101] 2. Stage I: Initial hydrogen flow rate 100 SCCM, oxygen flow rate 10 SCCM, heating time 25 seconds;

[0102] 3. Stage II: Hydrogen flow rate reduced to 70% of the initial value (70 SCCM), oxygen flow rate reduced to 15% of the initial value (2 SCCM), stretching speed 7 mm / min, stretching length 5 mm;

[0103] 4. Stage III: hydrogen flow rate 90 SCCM, oxygen flow rate 8 SCCM, heating time 18 seconds;

[0104] 5. Measurement results: The waist diameter was measured to be 14.80 μm (error -0.20 μm), and the length of the tapered transition zone was measured to be 1799.50 μm (error -0.50 μm); the standard deviations of the five batches were 0.20 μm and 0.03 μm respectively.

[0105] Example 4

[0106] Target parameters: waist diameter 8 microns, tapered transition zone length 1000 microns;

[0107] Process steps:

[0108] 1. Stage I: Initial hydrogen flow rate 110 SCCM, oxygen flow rate 10 SCCM, heating time 18 seconds;

[0109] 2. Stage II: The hydrogen flow rate was reduced to 85% of the initial value (94 SCCM), the oxygen flow rate was reduced to 18% of the initial value (2 SCCM), the stretching speed was 5 mm / min, and the stretching length was 3 mm;

[0110] 3. Stage III: heating time 12 seconds;

[0111] 4. Measurement results: waist diameter 8.10 μm (error +1.25%), tapered transition zone length 1000.40 μm (error +0.04%); standard deviations of the five batches were 0.12 μm and 0.30 μm respectively.

[0112] Example 5

[0113] Target parameters: waist diameter 12 microns, tapered transition zone length 1500 microns;

[0114] Process steps:

[0115] 1. Stage I: Initial hydrogen flow rate 120 SCCM, oxygen flow rate 15 SCCM, heating time 22 seconds;

[0116] 2. Stage II: The hydrogen flow rate was reduced to 70% of the initial value (84 SCCM), the oxygen flow rate was reduced to 15% of the initial value (2 SCCM), the stretching speed was 7 mm / min, and the stretching length was 5 mm;

[0117] 3. Stage III: heating time 16 seconds;

[0118] 4. Measurement results: waist diameter 11.80 μm (error -1.67%), tapered transition zone length 1499.80 μm (error -0.01%); standard deviations of the five batches were 0.18 μm and 0.25 μm respectively.

[0119] Example 6

[0120] Target parameters: waist diameter 20 microns, tapered transition zone length 2200 microns;

[0121] Process steps:

[0122] 1. Stage I: Initial hydrogen flow rate 90 SCCM, oxygen flow rate 6 SCCM, heating time 30 seconds;

[0123] 2. Stage II: The hydrogen flow rate was reduced to 75% of the initial value (68 SCCM), the oxygen flow rate was reduced to 16% of the initial value (1 SCCM), the stretching speed was 9 mm / min, and the stretching length was 7 mm;

[0124] 3. Stage III: Heating time 20 seconds;

[0125] 4. Measurement results: waist diameter 19.70 μm (error -1.5%), tapered transition zone length 2199.60 μm (error -0.02%); standard deviations of the five batches were 0.15 μm and 0.28 μm respectively.

[0126] Example 7

[0127] Target parameters: waist diameter 6 microns, tapered transition zone length 600 microns;

[0128] Process steps:

[0129] 1. Stage I: Initial hydrogen flow rate 130 SCCM, oxygen flow rate 12 SCCM, heating time 15 seconds;

[0130] 2. Stage II: The hydrogen flow rate was reduced to 78% of the initial value (101 SCCM), the oxygen flow rate was reduced to 17% of the initial value (2 SCCM), the stretching speed was 4 mm / min, and the stretching length was 2 mm;

[0131] 3. Stage III: heating time 10 seconds;

[0132] 4. Measurement results: waist diameter 6.20 μm (error +3.33%), tapered transition zone length 600.10 μm (error +0.02%); standard deviations of the five batches were 0.10 μm and 0.15 μm respectively.

[0133] Example 8

[0134] Target parameters: waist diameter 18 microns, tapered transition zone length 2000 microns;

[0135] Process steps:

[0136] 1. Stage I: Initial hydrogen flow rate 115 SCCM, oxygen flow rate 9 SCCM, heating time 28 seconds;

[0137] 2. Stage II: The hydrogen flow rate was reduced to 72% of the initial value (83 SCCM), the oxygen flow rate was reduced to 19% of the initial value (2 SCCM), the stretching speed was 8.5 mm / min, and the stretching length was 6.5 mm;

[0138] 3. Stage III: heating time 17 seconds;

[0139] 4. Measurement results: waist diameter 17.90 μm (error -0.56%), tapered transition zone length 2000.02 μm (error +0.01%); standard deviations of the five batches were 0.13 μm and 0.22 μm respectively.

[0140] Comparative Example 1 (Hydrogen / Oxygen Flow Rate Exceeds Upper Limit)

[0141] In phase II, the flow rate was not reduced, and a hydrogen flow rate of 150 SCCM (120% more than the initial value) and an oxygen flow rate of 25 SCCM (150% more than the initial value) were used directly. The target parameters were a waist diameter of 10 microns and a tapered transition zone length of 1200 microns.

[0142] Results: The optical fiber burned during the heating stage, the stretching was not completed, and the yield was 0%; when it broke, the waist diameter only dropped to 50 microns, far exceeding the target value.

[0143] Comparative Example 2 (hydrogen / oxygen flow rate is lower than the lower limit)

[0144] In stage II, the hydrogen flow rate is reduced to 60% of the initial value (below the lower limit of 70%), and the oxygen flow rate is reduced to 10% of the initial value (below the lower limit of 15%). The target parameters are a waist diameter of 12 microns and a tapered transition zone length of 1500 microns.

[0145] Results: The optical fiber was not fully melted and necked and fractured during stretching, with a yield rate of 20%. The length of the transition zone of the qualified samples fluctuated greatly, far exceeding the allowable error range.

[0146] Comparative Example 3 (first heating time is too long)

[0147] The heating time in stage I was set to 40 seconds (beyond the conventional range of 20-30 seconds), and the remaining parameters were set according to Example 2, with the target parameters being a waist diameter of 12 microns and a tapered transition zone length of 1500 microns.

[0148] Results: The optical fiber burned during the heating stage, the stretching was not completed, and the yield was 0%; when it broke, the waist diameter only dropped to 50 microns, far exceeding the target value.

[0149] Comparative Example 4 (second heating time is too short)

[0150] The heating time in stage III is set to 5 seconds (less than the conventional 10 seconds), and the remaining parameters are set according to Example 1, with the target parameters being a waist diameter of 10 microns and a tapered transition zone length of 1200 microns.

[0151] Results: The diameter of the waist area was only reduced to 15 microns (below the target value), the surface of the transition zone was not smooth, and stress concentration defects occurred due to insufficient melting.

[0152] The specific comparison between the embodiment of the micro-nano optical fiber finishing method of the present invention and the above comparative example is shown in Table 1 below.

[0153]

[0154]

[0155] Table 1

[0156] In summary, the present invention uses a method of simultaneously adjusting multiple variables to control the micro-nano optical fiber finishing process, avoiding product quality issues caused by a single variable, and can accurately control the size and morphology of the optical fiber, solving the problems of relying on experience and extensive adjustment in the existing technology. Based on the morphology-controllable micro-nano optical fiber finishing technology of the present invention, high-precision and repeatable preparation of micro-nano optical fibers is achieved, which has important engineering significance for the rapid development of micro-nano optical fiber processing technology. The above content is only an example of a specific solution of the present invention. For equipment and structures not described in detail, it should be understood that they are implemented using general equipment and methods already in the field.

[0157] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A micro-nano optical fiber precision processing method, characterized in that: The following steps are involved: Step S1, single-mode optical fiber pretreatment; Step S2: fixing the single-mode optical fiber, adjusting the flow rates of hydrogen and oxygen to initial values, and heating the middle position for a first heating time; Step S3, reducing the flow rate of hydrogen and oxygen, and reversely stretching the optical fiber at a preset stretching speed until it reaches a preset stretching length, and then stopping the stretching; Step S4: adjust the flow rates of hydrogen and oxygen again and heat the middle position for a second heating time; Step S5: Stop heating and obtain a micro-nano optical fiber of target size, wherein the target size includes the waist diameter D w , length of tapered transition zone L t and cone angle Ω(z) The preset stretching speed and the preset stretching length are determined by the waist diameter D w , length of tapered transition zone L t Calculated, expressed as: Among them, t1 represents the first heating time, t2 represents the second heating time, Q1 represents the initial hydrogen flow rate in step S2, Q2 represents the initial oxygen flow rate in step S2, f1(t1, t2, Q1, Q2), f2(t1, t2, Q1, Q2), g1(t1, t2, Q1, Q2) and g2(t1, t2, Q1, Q2) represent process coefficients.

2. The finishing method according to claim 1, characterized in that: Also includes: Step S6: Measure the size of the micro-nano optical fiber with the target size obtained in step S5; based on the waist diameter D obtained by measurement w , length of tapered transition zone L t Determine the cone angle Ω(z).

3. The finishing method according to claim 2, characterized in that: Waist diameter D w , the length of the tapered transition zone L t The relationship with the cone angle Ω(z) is expressed as:

4. The finishing method according to claim 1, characterized in that: The process coefficient is determined by the process factor K, which is specifically expressed as: Then we have:

5. The finishing method according to claim 1, wherein: In the step S3, the hydrogen flow rate is reduced to 70% to 80% of the initial hydrogen flow rate; and the oxygen flow rate is reduced to 15% to 20% of the initial oxygen flow rate.

6. The finishing method according to claim 1, characterized in that: The step S1 comprises: Remove about 3-5 cm of coating from the surface of the single-mode optical fiber and wipe the surface of the single-mode optical fiber clean.

7. The finishing method according to claim 6, characterized in that: The step S2 comprises: Placing the single-mode optical fiber in the optical fiber clamps on the left and right sides of the optical fiber taper machine; Adjust the fixture spacing; The middle position of the single-mode optical fiber is heated using an oxyhydrogen flame, and the heating time is the first heating time.

8. The finishing method according to claim 1, wherein: The step S5 comprises: The oxyhydrogen flame gas source is turned off, and after stopping heating, the micro-nano optical fiber is kept in the fixture and naturally cooled to room temperature.

9. The finishing method according to claim 2, characterized in that: The step S6 comprises: Fix the micro-nano optical fiber on the stage, adjust the light source and magnification to clearly display the waist and transition zones, and record the actual values of the waist diameter and the length of the tapered transition zone using the microscope measurement software.

10. The finishing method according to claim 1, characterized in that: The machining error of the waist diameter is less than 40μm, and the length of the tapered transition zone is L t The processing error is less than 0.5μm.

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