Method for manufacturing polygonal tapered optical fiber

Abstract

This invention provides a method for fabricating polygonal tapered optical fibers. During the entire drawing process, the actual circumscribed circle diameter and actual inscribed circle diameter of the fiber are measured accurately in real time. These actual circumscribed circle and inscribed circle diameters are compared with the theoretical circumscribed circle and inscribed circle diameters. Drawing parameters are adjusted based on the differences, forming a closed-loop control system. This feedback control is implemented throughout the entire drawing process, ensuring the accuracy of the drawn polygonal tapered optical fiber. This invention enables the precise fabrication of polygonal tapered optical fibers of different sizes. Furthermore, the feedback control during the fabrication process ensures that the polygonal structure of the fiber is precisely maintained during the drawing of the tapered region.

Description

Technical Field

[0001] This invention mainly relates to the field of optical fiber fabrication technology, and in particular to a method for fabricating polygonal tapered optical fibers. Background Technology

[0002] Polygonal optical fibers differ from ordinary circular optical fibers. Preforms of different shapes are initially drawn into a circular shape in a high-temperature furnace. In order to draw the optical fiber into the required shape, it is necessary to adjust the temperature of the high-temperature furnace, the feeding speed of the preform, and the optical fiber preparation speed. After reaching a certain balance point, the optical fiber will take on the required shape.

[0003] During the drawing process of polygonal tapered optical fiber, the drawing speed varies, and the speed varies by multiples. Therefore, in order to produce qualified polygonal tapered optical fiber while maintaining the polygonal shape of the fiber, a precise control method is required. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention proposes a method for preparing polygonal tapered optical fibers.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On one hand, the present invention provides a method for fabricating a polygonal tapered optical fiber, comprising:

[0007] (1) Prepare a regular polygonal preform, wherein the diameter of the inscribed circle of the regular polygonal preform is D. 内 The diameter of the circumscribed circle is D 外 ;

[0008] (2) Determine the drawing speed and temperature of the thick end of the polygonal tapered fiber, and determine the drawing speed and temperature of the thin end of the polygonal tapered fiber. The drawing speed range of the tapered region of the polygonal tapered fiber is between the drawing speed of the thick end and the drawing speed of the thin end, and the drawing temperature range of the tapered region of the polygonal tapered fiber is between the drawing temperature of the thick end and the drawing temperature of the thin end.

[0009] (3) The end point of the thick end of the polygonal tapered fiber is the starting point of the tapered region where the tapered fiber needs to be drawn. The theoretical inscribed circle diameter of the fiber at the starting point of the tapered region is the inscribed circle diameter d of the thick end of the polygonal tapered fiber. 1,内 The theoretical circumscribed circle diameter of the optical fiber at the starting point of the cone region is the same as the circumscribed circle diameter d at the thicker end of the polygonal tapered optical fiber. 1,外 ;

[0010] (4) Determine the end position of the tapered section of the polygonal tapered fiber based on the preset tapered section length L3. The end position of the tapered section is the starting position of the thin end of the polygonal tapered fiber. The preset thin end length L2 of the polygonal tapered fiber is the theoretical inscribed circle diameter of the fiber at the end position of the tapered section, which is the inscribed circle diameter d of the thin end. 2,内 The theoretical circumcircle diameter of the optical fiber at the end of the conical region, i.e., the circumcircle diameter d of the narrow end. 2,外 ;

[0011] (5) Based on the inscribed circle diameter of the theoretical fiber at the starting point of the cone region, the circumscribed circle diameter of the theoretical fiber at the starting point of the cone region, the cone region length L3 of the polygonal tapered fiber, the inscribed circle diameter of the theoretical fiber at the ending point of the cone region, and the circumscribed circle diameter of the theoretical fiber at the ending point of the cone region, determine the inscribed circle diameter and the circumscribed circle diameter of the theoretical fiber at any position along the length of the cone region.

[0012] (6) Under the rough-end drawing speed and rough-end drawing temperature, based on the drawing length L1 of the regular polygonal preform and the inscribed circle diameter d 1,内 The diameter of the circumscribed circle is d 1,外 The thick end of the polygonal tapered optical fiber;

[0013] (7) Start drawing the tapered fiber from the determined starting point of the tapered fiber tapered region;

[0014] (7.1) During the tapered fiber drawing process, the actual inscribed circle diameter d of the fiber at the current drawing position is measured in real time. (实内) The diameter d of the circumscribed circle of the actual optical fiber (实外) Obtain the actual inscribed circle diameter d of the optical fiber at the current drawing position. (实内) The diameter d of the inscribed circle of the theoretical optical fiber (理内) The real-time difference is the first deviation value. The current tapered zone drawing speed is adjusted in real time according to the first deviation value, and then proceed to step (7.2).

[0015] (7.2) The inscribed circle diameter d of the actual optical fiber at the current drawing position (实内) and the actual outer diameter d of the optical fiber (实外) The real-time difference is compared with the theoretical inscribed circle diameter d of the optical fiber at the current drawing position. (理内) The diameter d of the circumscribed circle of the theoretical optical fiber (理外) The theoretical difference is used to obtain the second deviation value, and then proceed to step (7.3);

[0016] (7.3) Adjust the current cone zone drawing temperature T according to the second deviation value, return to step (7.1), until the current drawing position is the cone zone end point position, and complete the cone zone drawing;

[0017] (8) Keep the drawing parameters unchanged while keeping the end point position of the cone region unchanged. The drawing parameters include drawing temperature and drawing speed to complete the drawing of the fine end of the polygonal tapered optical fiber with a length of L2.

[0018] On the other hand, a polygonal tapered optical fiber is provided, the cross-section of which is a regular polygon, and it is obtained by the above-mentioned method for preparing polygonal tapered optical fibers.

[0019] On the other hand, a laser system is provided, comprising a polygonal tapered optical fiber obtained by the above-described method for fabricating polygonal tapered optical fibers.

[0020] Compared with the prior art, the technical effects of the present invention are as follows:

[0021] This invention enables the precise fabrication of polygonal tapered optical fibers of different sizes. Furthermore, through feedback control during the fabrication process, it ensures that the polygonal structure of the optical fiber is precisely maintained during the drawing of the polygonal tapered region. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a polygonal tapered optical fiber;

[0024] Figure 2 It is a cross-sectional view of a regular polygonal precast bar;

[0025] Figure 3 This is a theoretical curve showing the changes in the circumscribed circle diameter, inscribed circle diameter, and drawing speed during the tapered drawing process.

[0026] Figure 4 This is a comparison chart of the actual and theoretical variation curves of the circumscribed / inscribed circle diameters during the tapered zone drawing process using existing methods.

[0027] Figure 5 A comparison diagram of the theoretical and actual cross-sectional shapes obtained by existing methods during the tapered zone drawing process;

[0028] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] In one embodiment, a method is provided as follows: Figure 1 The method for fabricating the polygonal tapered optical fiber shown includes:

[0031] (1) Prepare a regular polygonal preform, wherein the diameter of the inscribed circle of the regular polygonal preform is D(inner), and the diameter of the circumscribed circle is D(outer). The cross-section of the regular polygonal preform is as follows: Figure 2 As shown.

[0032] (2) Determine the drawing speed and temperature of the thick end of the polygonal tapered fiber, and determine the drawing speed and temperature of the thin end of the polygonal tapered fiber. The drawing speed range of the tapered region of the polygonal tapered fiber is between the drawing speed of the thick end and the drawing speed of the thin end, and the drawing temperature range of the tapered region of the polygonal tapered fiber is between the drawing temperature of the thick end and the drawing temperature of the thin end.

[0033] (3) The end point of the thick end of the polygonal tapered fiber is the starting point of the tapered region where the tapered fiber needs to be drawn. The theoretical inscribed circle diameter of the fiber at the starting point of the tapered region is the inscribed circle diameter d of the thick end of the polygonal tapered fiber. 1,内 The theoretical circumscribed circle diameter of the optical fiber at the starting point of the cone region is the same as the circumscribed circle diameter d at the thicker end of the polygonal tapered optical fiber. 1,外 ;

[0034] (4) Determine the end position of the tapered section of the polygonal tapered fiber based on the preset tapered section length L3. The end position of the tapered section is the starting position of the thin end of the polygonal tapered fiber. The preset thin end length L2 of the polygonal tapered fiber is the theoretical inscribed circle diameter of the fiber at the end position of the tapered section, which is the inscribed circle diameter d of the thin end. 2,内 The theoretical circumcircle diameter of the optical fiber at the end of the conical region, i.e., the circumcircle diameter d of the narrow end. 2,外 ;

[0035] (5) Based on the inscribed circle diameter of the theoretical fiber at the starting point of the cone region, the circumscribed circle diameter of the theoretical fiber at the starting point of the cone region, the cone region length L3 of the polygonal tapered fiber, the inscribed circle diameter of the theoretical fiber at the ending point of the cone region, and the circumscribed circle diameter of the theoretical fiber at the ending point of the cone region, determine the inscribed circle diameter and the circumscribed circle diameter of the theoretical fiber at any position along the length of the cone region.

[0036] (6) Under the rough-end drawing speed and rough-end drawing temperature, based on the drawing length L1 of the regular polygonal preform and the inscribed circle diameter d 1,内 The diameter of the circumscribed circle is d 1,外 The thick end of the polygonal tapered optical fiber;

[0037] (7) Start drawing the tapered fiber from the determined starting point of the tapered fiber tapered region;

[0038] (7.1) During the tapered fiber drawing process, the actual inscribed circle diameter d of the fiber at the current drawing position is measured in real time. (实内) The diameter d of the circumscribed circle of the actual optical fiber (实外) Obtain the actual inscribed circle diameter d of the optical fiber at the current drawing position. (实内) The diameter d of the inscribed circle of the theoretical optical fiber (理内) The real-time difference is the first deviation value. The current tapered zone drawing speed is adjusted in real time according to the first deviation value, and then proceed to step (7.2).

[0039] (7.2) The inscribed circle diameter d of the actual optical fiber at the current drawing position (实内) and the actual outer diameter d of the optical fiber (实外) The real-time difference is compared with the theoretical inscribed circle diameter d of the optical fiber at the current drawing position. (理内) The diameter d of the circumscribed circle of the theoretical optical fiber (理外) The theoretical difference is used to obtain the second deviation value, and then proceed to step (7.3);

[0040] (7.3) Adjust the current cone zone drawing temperature T according to the second deviation value, return to step (7.1), until the current drawing position is the cone zone end point position, and complete the cone zone drawing;

[0041] (8) Keep the drawing parameters unchanged while keeping the end point position of the cone region unchanged. The drawing parameters include drawing temperature and drawing speed to complete the drawing of the fine end of the polygonal tapered optical fiber with a length of L2.

[0042] Further, in step (7.1) of a preferred embodiment, the current conical drawing speed is adjusted in real time according to the first deviation value, and the method is as follows: when the first deviation value is greater than 0, the current conical drawing speed is increased within the range of conical drawing speed with the goal of making the first deviation value closer to 0 or even equal to 0; when the first deviation value is less than 0, the current drawing speed is decreased within the range of conical drawing speed with the goal of making the first deviation value closer to 0 or even equal to 0.

[0043] Further, in step (7.3) of a preferred embodiment, adjusting the current cone drawing temperature T according to the second deviation value includes: when the second deviation value is greater than 0, increasing the current cone drawing temperature T within the cone drawing temperature range with the goal of making the second deviation value closer to 0 or even equal to 0; and when the second deviation value is less than 0, decreasing the current cone drawing temperature T within the cone drawing temperature range with the goal of making the second deviation value closer to 0 or even equal to 0.

[0044] In addition, the regular polygonal preforms described in this invention include, but are not limited to, preforms with regular pentagons, regular hexagons, or regular octagons.

[0045] This invention ensures that the polygonal structure of the optical fiber is precisely maintained during the drawing process of the polygonal tapered region by real-time feedback control of the drawing speed and temperature of the tapered region, so that the drawn polygonal tapered optical fiber can be very close to the ideal polygonal tapered optical fiber size and structural shape.

[0046] Furthermore, during the drawing process of the polygonal tapered optical fiber, fiber coating is also performed simultaneously. During the drawing process, as the fiber diameter decreases, the coating thickness changes accordingly, the drawing speed continuously increases, and the amount of coating consumed changes accordingly. Based on the real-time measurement of the fiber diameter after coating by the fiber diameter measurement system, the coating pressure P is controlled in real time. Simultaneously, the time it takes for the coated fiber to pass through the curing equipment decreases, and the curing power Pow of the curing equipment is also controlled in real time according to the change in drawing speed.

[0047] Furthermore, during the tapered fiber drawing process, the start and end positions of the polygonal tapered fiber are simultaneously marked: when drawing the polygonal tapered fiber, the fiber drawing length L at the start of the drawing process and the length L4 from the output port of the polygonal tapered fiber to the fiber take-up machine are determined; when the fiber drawing length is equal to L+L4, the start position of the polygonal tapered fiber is marked at the corresponding position of the fiber; when the fiber drawing length is equal to L+L1+L2+L3+L4, the end position of the polygonal tapered fiber is marked at the corresponding position of the fiber.

[0048] The resulting polygonal tapered optical fiber has a regular polygonal cross-section, meaning its cladding is a regular polygon. Regular polygons are not limited to regular pentagons, regular hexagons, regular octagons, etc.

[0049] Furthermore, based on the theoretical incircle diameter of the fiber at the starting point of the cone region, the theoretical circumcircle diameter of the fiber at the starting point of the cone region, the cone region length L3 of the polygonal tapered fiber, the incircle diameter of the fiber at the ending point of the cone region, and the theoretical circumcircle diameter of the fiber at the ending point of the cone region, the theoretical curves of wire diameter variation (including the theoretical curves of circumcircle diameter variation and incircle diameter variation during the cone region drawing process) are calculated. This is done according to the formula that the speed ratio is the square of the wire diameter ratio. The theoretical speed curve is calculated, which determines the relationship between the drawing speed of the thick end and the drawing speed of the thin end of the polygonal tapered fiber. Based on this, the range of drawing speeds for the tapered region of the polygonal tapered fiber is determined. Figure 3 The figure shows the theoretical variation curves of the circumscribed circle diameter, inscribed circle diameter, and drawing speed during the tapered zone drawing process.

[0050] However, in the actual tapered drawing process, if... Figure 3 The theoretical curve of the drawing speed shown is used for speed control. However, due to system hysteresis and the uniformity of the preform itself, the wire diameter variation curve will exhibit the following characteristics: Figure 4 The trend shown, Figure 5 This image shows a comparison between the theoretical and actual cross-sectional shapes obtained using existing methods during the tapered drawing process. From... Figure 4 As can be seen, two problems arise: First, the wire diameter (circumscribed circle diameter and inscribed circle diameter) cannot reach the theoretical value at a specific length position; second, the wire diameter (circumscribed circle diameter and inscribed circle diameter) fluctuates near the thinner end, due to the butterfly effect caused by the first problem. From Figure 5 As can be seen, the cross-sectional shape of the drawn optical fiber is becoming increasingly round, and it is no longer a polygonal shape. The solution to these two problems is to ensure that the fiber diameter changes according to or close to the theoretical value.

[0051] In the entire process of drawing polygonal tapered optical fibers, this invention accurately measures the actual wire diameter (actual circumscribed circle diameter and actual inscribed circle diameter) of the fiber in real time. The actual circumscribed circle diameter and actual inscribed circle diameter are compared with the theoretical circumscribed circle diameter and theoretical inscribed circle diameter to calculate the real-time difference. Based on this difference, the control system performs corresponding proportional control on the theoretical speed value according to the ratio of the difference to the theoretical value, forming a closed-loop control. Feedback control runs through the entire process of drawing polygonal tapered optical fibers, ensuring the accuracy of the drawn polygonal tapered optical fibers.

[0052] The tapering process of polygonal tapered optical fibers is a dynamically controlled process, and also the most crucial one. The quality of this control significantly impacts the stability of the fiber diameter at the beginning of the tapered fiber's narrow end. If a large deviation (d) occurs between the set values ​​of the fiber diameter and the narrow-end fiber diameter at the completion of tapering, the process will be severely affected. (偏) The system control will exhibit an oscillation process; the oscillation range and duration depend on d. (偏) Size.

[0053] In one embodiment, a polygonal tapered optical fiber is provided, specifically a regular polygonal tapered optical fiber, wherein the cross-section of the polygonal tapered optical fiber is a regular polygon, and it is obtained by the preparation method of the polygonal tapered optical fiber described in any of the above embodiments.

[0054] One embodiment provides a laser system including a polygonal tapered optical fiber obtained by the fabrication method of the polygonal tapered optical fiber described in any of the above embodiments, wherein the cross-section of the polygonal tapered optical fiber is a regular polygon.

[0055] Advantages of regular polygonal optical fibers: First, there's the difference between circular and regular polygonal optical fibers. For gain fibers, to enhance the absorption of pump light, the inner cladding structure is usually changed from circular to polygonal. This increases the probability that the pump light will travel a greater distance through the center of the cladding, thus enhancing linear absorption. If a circular structure with a central knot is used, the pump light is more likely to generate spiral light during transmission and cannot pass through the center. Therefore, in laser applications, a regular polygonal inner cladding structure has a greater advantage in enhancing pump absorption.

[0056] The advantage of polygonal tapered optical fibers, especially regular polygonal tapered optical fibers, lies in their ability to control beam quality without altering the fiber's absorption coefficient for pump light. As the beam propagates from the narrow end to the thicker end, the narrow end ensures good beam quality, while the thicker end guarantees the power density of the high-power laser in the linear configuration. More specifically, the thicker end reduces the power density of the high-power laser in the fiber core, mitigating nonlinear effects. Furthermore, the tapered transition region from narrow to thick uses a long draw tapered section to ensure that beam quality does not degrade during propagation from the narrow to the thicker end. In other words, the polygonal tapered optical fiber proposed in this invention integrates multiple advantages, including achieving the same pump absorption capacity as ordinary large-diameter optical fibers, ensuring beam quality during laser transmission, and reducing laser-material interactions and nonlinear effects.

[0057] Matters not covered in this invention are common knowledge.

[0058] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating polygonal tapered optical fibers, characterized in that, include: (1) Prepare a regular polygonal preform, wherein the diameter of the inscribed circle of the regular polygonal preform is D. 内 The diameter of the circumscribed circle is D 外 ; (2) Determine the drawing speed and temperature of the thick end of the polygonal tapered fiber, and determine the drawing speed and temperature of the thin end of the polygonal tapered fiber. The drawing speed range of the tapered region of the polygonal tapered fiber is between the drawing speed of the thick end and the drawing speed of the thin end, and the drawing temperature range of the tapered region of the polygonal tapered fiber is between the drawing temperature of the thick end and the drawing temperature of the thin end. (3) The end point of the thick end of the polygonal tapered fiber is the starting point of the tapered region where the tapered fiber needs to be drawn. The theoretical inscribed circle diameter of the fiber at the starting point of the tapered region is the inscribed circle diameter d of the thick end of the polygonal tapered fiber. 1,内 The theoretical circumscribed circle diameter of the optical fiber at the starting point of the cone region is the circumscribed circle diameter d of the thicker end of the polygonal tapered optical fiber. 1,外 ; (4) Determine the end position of the tapered section of the polygonal tapered fiber based on the preset tapered section length L3. The end position of the tapered section is the starting position of the thin end of the polygonal tapered fiber. The preset thin end length L2 of the polygonal tapered fiber is the theoretical inscribed circle diameter of the fiber at the end position of the tapered section, which is the inscribed circle diameter d of the thin end. 2,内 The theoretical circumcircle diameter of the optical fiber at the end of the conical region, i.e., the circumcircle diameter d of the narrow end. 2,外 ; (5) Based on the inscribed circle diameter of the theoretical fiber at the starting point of the cone region, the circumscribed circle diameter of the theoretical fiber at the starting point of the cone region, the cone region length L3 of the polygonal tapered fiber, the inscribed circle diameter of the theoretical fiber at the ending point of the cone region, and the circumscribed circle diameter of the theoretical fiber at the ending point of the cone region, determine the inscribed circle diameter and the circumscribed circle diameter of the theoretical fiber at any position along the length of the cone region. (6) Under the rough-end drawing speed and rough-end drawing temperature, based on the drawing length L1 of the regular polygonal preform and the diameter of the inscribed circle d 1,内 The diameter of the circumscribed circle is d 1,外 The thick end of the polygonal tapered optical fiber; (7) Start drawing the tapered fiber from the determined starting point of the tapered fiber tapered region; (7.1) During the tapered fiber drawing process, the actual inscribed circle diameter d of the fiber at the current drawing position is measured in real time. (实内) The diameter d of the circumscribed circle of the actual optical fiber (实外) Obtain the actual inscribed circle diameter d of the optical fiber at the current drawing position. (实内) The diameter d of the inscribed circle of the theoretical optical fiber (理内) The real-time difference is the first deviation value. The current tapered zone drawing speed is adjusted in real time according to the first deviation value, and then proceed to step (7.2). (7.2) The inscribed circle diameter d of the actual optical fiber at the current drawing position (实内) and the actual outer diameter d of the optical fiber (实外) The real-time difference is compared with the theoretical inscribed circle diameter d of the optical fiber at the current drawing position. (理内) The diameter d of the circumscribed circle of the theoretical optical fiber (理外) The theoretical difference is used to obtain the second deviation value, and then proceed to step (7.3); (7.3) Adjust the current cone drawing temperature T according to the second deviation value, return to step (7.1), until the current drawing position is the end point of the cone, and complete the cone drawing; (8) Keep the drawing parameters unchanged while keeping the end point position of the cone region unchanged. The drawing parameters include drawing temperature and drawing speed to complete the drawing of the fine end of the polygonal tapered optical fiber with a length of L2.

2. The method for fabricating polygonal tapered optical fiber according to claim 1, characterized in that, In step (6.1), the current tapered zone drawing speed is adjusted in real time according to the first deviation value. The method is as follows: when the first deviation value is greater than 0, the current tapered zone drawing speed is increased within the range of tapered zone drawing speed with the goal of making the first deviation value closer to 0 or even equal to 0. When the first deviation value is less than 0, the current drawing speed is decreased within the range of tapered zone drawing speed with the goal of making the first deviation value closer to 0 or even equal to 0.

3. The method for fabricating a polygonal tapered optical fiber according to claim 1 or 2, characterized in that, In step (7.3), the current cone drawing temperature T is adjusted according to the second deviation value. The method includes: when the second deviation value is greater than 0, the current cone drawing temperature T is increased within the cone drawing temperature range with the goal of making the second deviation value closer to 0 or even equal to 0; when the second deviation value is less than 0, the current cone drawing temperature T is decreased within the cone drawing temperature range with the goal of making the second deviation value closer to 0 or even equal to 0.

4. The method for fabricating polygonal tapered optical fiber according to claim 3, characterized in that, The regular polygonal preform is a regular pentagonal, regular hexagonal, or regular octagonal preform.

5. The method for fabricating a polygonal tapered optical fiber according to claim 1, 2, or 4, characterized in that, During the drawing process of polygonal tapered optical fiber, fiber coating is also carried out simultaneously. As the fiber diameter decreases during the drawing process, the thickness of the fiber coating also changes accordingly. The drawing speed continuously increases, and the consumption of coating material changes accordingly. Based on the fiber diameter measured in real time by the fiber diameter measurement system after coating, the coating pressure P is controlled in real time. At the same time, the time for the coated fiber to pass through the curing equipment is shortened, and the curing power Pow of the curing equipment is also controlled in real time according to the change of drawing speed.

6. The method for fabricating a polygonal tapered optical fiber according to claim 5, characterized in that, During the tapered fiber drawing process, the start and end positions of the polygonal tapered fiber are also marked simultaneously: when drawing the polygonal tapered fiber, the fiber drawing length L at the start of the drawing process and the length L4 from the output port of the polygonal tapered fiber to the fiber take-up machine are determined; when the fiber drawing length is equal to L+L4, the start position of the polygonal tapered fiber is marked at the corresponding position of the fiber; when the fiber drawing length is equal to L+L1+L2+L3+L4, the end position of the polygonal tapered fiber is marked at the corresponding position of the fiber.

7. A polygonal tapered optical fiber, characterized in that, The polygonal tapered optical fiber has a regular polygonal cross-section and is obtained by the preparation method of the polygonal tapered optical fiber as described in claim 1.

8. The polygonal tapered optical fiber according to claim 6, characterized in that, Polygonal tapered optical fibers have cross-sections that are regular pentagonal, regular hexagonal, or regular octagonal.

9. A laser system, characterized in that, This includes polygonal tapered optical fibers obtained using the fabrication method of the polygonal tapered optical fiber as described in claim 1, wherein the cross-section of the polygonal tapered optical fiber is a regular polygon.

10. The laser system according to claim 9, characterized in that, Polygonal tapered optical fibers have cross-sections that are regular pentagonal, regular hexagonal, or regular octagonal.

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