Method for manufacturing thermal diffusion optical fiber

Abstract

The invention discloses a manufacturing method of a thermal diffusion optical fiber. The manufacturing method is characterized by comprising the following steps: removing a coating layer in an optical fiber heating area; the rotary clamping platform is used for clamping the parts, corresponding to the two sides of the heating area, of the optical fiber, constant tension is applied, and the optical fiber is driven to rotate at a constant speed; heating the heating area of the optical fiber by adopting a heating source so as to perform thermal diffusion treatment on the optical fiber; a reverse tapering process is performed on the heating area before or after thermal diffusion to compensate for the diameter change of the optical fiber. By introducing the constant-speed rotation and reverse tapering process, it is ensured that mode field expansion is symmetrical and the diameter of the optical fiber is stable, and therefore connection loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber manufacturing, and in particular to a manufacturing method of a thermal diffusion optical fiber. BACKGROUND

[0002] Thermal diffusion optical fiber refers to a process of changing the refractive index distribution of the fiber core by local heating, so as to locally increase the mode field diameter of the optical fiber. When the mode field diameter of the thermal diffusion optical fiber matches that of the subsequent butt joint optical fiber, the fusion loss or coupling loss between them is minimized, generally close to zero.

[0003] In an optical fiber communication system, the output of the optical chip waveguide is usually only about 3 μm in mode field diameter at the 1550 nm wavelength band, while the mode field diameter of the conventional single-mode optical fiber is about 10.5 μm at the 1550 nm wavelength band, which results in a fusion loss of more than 3 dB when directly coupled, i.e. more than 50% of the optical energy is lost. To solve this problem, some companies have specially developed single-mode optical fibers (small mode field optical fibers) with a mode field diameter of only about 3 μm at the 1550 nm wavelength band, but such optical fibers are very expensive, about 200 times the cost of conventional optical fibers, and are difficult to be widely used. The thermal diffusion technology changes the refractive index distribution of the 3 μm mode field optical fiber by local heating, thereby expanding the mode field diameter and realizing the matching with the conventional optical fiber, and reducing the loss to below 0.2 dB. Therefore, in practical applications, the length of the small mode field optical fiber can be very short, which can greatly reduce the length of the small mode field optical fiber, thereby reducing the cost, and at the same time, the small mode field optical fiber can be matched with the external system optical fiber.

[0004] In addition, there is a kind of optical fiber called "anti-resonant hollow core optical fiber" on the market at present. This kind of optical fiber is favored by communication operators and investors because of its ultra-low transmission loss, low optical transmission delay, ultra-low dispersion, excellent bandwidth characteristics, and ultra-low optical nonlinear effect, and will have important applications in the fields of optical fiber communication, data center, sensing, and fiber laser in the future. However, the characteristic of this kind of hollow core optical fiber is that its mode field diameter at the 1550 nm wavelength reaches 25 μm, which cannot be achieved like the mode field diameter of the conventional single-mode optical fiber, otherwise the optical transmission loss will be very large. Therefore, when connected with the conventional fiber, the mode field of the conventional optical fiber needs to be expanded to about 25 μm.

[0005] However, in the process of expanding the mode field of the conventional optical fiber to 25 μm or a larger size, a long time is needed for thermal diffusion, which will cause two problems: first, the optical fiber does not rotate during heating, and the heating is uneven, resulting in an asymmetric or elliptical mode field expansion; second, long-time heating causes the diameter of the heated area of the optical fiber to decrease by 2%-3%, causing the optical fiber to be off-center and increasing the connection loss with the hollow core optical fiber or other large mode field optical fiber. Therefore, an improved manufacturing method is urgently needed to solve the problems of mode field asymmetry and diameter reduction. SUMMARY

[0006] To address the shortcomings of existing technologies, this invention provides a method for manufacturing thermally diffused optical fibers. By introducing uniform rotation and inverted tapering processes, the method ensures symmetrical mode field expansion and stable fiber diameter, thereby reducing connection loss.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for manufacturing a heat-diffusion optical fiber, characterized by comprising the following steps: Remove the coating layer from the heated area of ​​the optical fiber; The optical fiber is clamped on both sides of the heating area using a rotating clamping platform, and a constant tension is applied to drive the optical fiber to rotate at a uniform speed. A heating source is used to heat the heating area of ​​the optical fiber to perform thermal diffusion treatment on the optical fiber; Before or after thermal diffusion, the heated area is subjected to a tapered process to compensate for changes in fiber diameter.

[0008] Preferably, the length of the removed coating layer is 15–30 mm.

[0009] Preferably, the rotational speed at which the rotating clamping platform drives the optical fiber to rotate is greater than 10 revolutions per minute.

[0010] Preferably, the heating source is an oxyhydrogen flame, and the heating temperature is at least 1000°C.

[0011] Preferably, the heating source moves back and forth along the orientation of the optical fiber heating region at a speed of 2 to 5 mm / s.

[0012] Preferably, the inverted tapering process increases the fiber diameter by 1%-3%.

[0013] The advantages of this invention are: highly symmetrical mode field expansion, reducing splicing loss; stable fiber diameter, avoiding eccentricity issues; good process consistency, suitable for large-scale production. Attached Figure Description

[0014] Fig. 1 This is a schematic diagram of the manufacturing method of the heat-diffusion optical fiber provided in this embodiment; Fig. 2 This is a flowchart of the manufacturing method of the heat-diffusion optical fiber provided in this embodiment; Fig. 3 This is another implementation flowchart of the manufacturing method of the heat-diffusion optical fiber provided in this embodiment. Detailed Implementation

[0015] Combination Figs. 1 to 3 The manufacturing method of the thermally diffusing optical fiber of the present invention will be further described.

[0016] A method for manufacturing a heat-diffusion optical fiber, characterized by comprising the following steps: First, the coating layer in the heated area of ​​the optical fiber is removed, with a length of 15-30 mm being removed.

[0017] A rotating clamping platform is used to clamp the optical fiber at both ends corresponding to the heating area, with the clamping points 3-5 mm away from the heating area. A constant tension is then applied to straighten the area between the two clamping points, improving process repeatability and causing the fiber to rotate at a uniform speed. During this process, the rotating clamping platform rotates the fiber at a speed greater than 10 revolutions per minute. The rotating clamping platform can be purchased commercially. The clamping force and tension should be such that they do not damage the fiber itself; they only need to clamp, straighten, and rotate the fiber. The clamping force remains constant during rotation. Because the optical fiber softens after heating, the constant force applied by the rotating clamping platform to both ends of the heating area is reduced after heating, ensuring no damage to the fiber.

[0018] A heating source is used to heat the optical fiber's heating area to perform thermal diffusion treatment. During heating, the heating source moves back and forth along the fiber's heating area at a speed of 2–5 mm / s to achieve a larger heating area and uniform heating, meeting the requirements for the length of the thermal diffusion area. Given a fixed heating area range and heating source moving speed, more repetitions mean a longer cumulative heating time. A longer heating time results in a larger mode field expansion; therefore, the specific heating time is related to the required mode field size, generally between 40 and 80 minutes. The heating source is an oxyhydrogen flame with a heating temperature of at least 1000°C. During the heating process, the heating source temperature and rotation speed remain constant.

[0019] Before or after thermal diffusion, the heating area is subjected to a reverse tapering process, which can increase the diameter of the heating area by 1%-3% to compensate for changes in the fiber diameter. Finally, the desired thermally diffusing optical fiber is obtained.

[0020] The following describes the thermal diffusion treatment of a conventional optical fiber with an output wavelength of 1550 nm and a mode field diameter of 10.5 μm. During the thermal diffusion process, conventional conditions were used, namely a constant temperature of 1000 °C, a constant speed of 3 mm / s, a constant rotation speed of 10 rpm, a coating removal length of 20 mm, and heating times of 40 minutes, 60 minutes, and 80 minutes, respectively, to obtain multiple sets of examples and comparative examples to further illustrate this manufacturing method. Example

[0021] Remove the coating layer from the heated area of ​​the optical fiber.

[0022] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0023] A heating source is used to heat the heating area of ​​the optical fiber for 40 minutes to perform thermal diffusion treatment on the optical fiber.

[0024] After thermal diffusion, the heated area is subjected to a reverse tapering process, which increases the diameter of the heated area by 1% to compensate for the change in fiber diameter; Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 25 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%. Example

[0025] Remove the coating layer from the heated area of ​​the optical fiber.

[0026] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0027] A heating source is used to heat the heating area of ​​the optical fiber for 60 minutes to perform thermal diffusion treatment on the optical fiber.

[0028] After thermal diffusion, the heated area is subjected to a reverse tapering process, which increases the diameter of the heated area by 2% to compensate for the change in fiber diameter; Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 30 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%. Example

[0029] Remove the coating layer from the heated area of ​​the optical fiber.

[0030] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0031] A heating source is used to heat the heating area of ​​the optical fiber for 80 minutes to perform thermal diffusion treatment on the optical fiber.

[0032] After thermal diffusion, the heated area is subjected to a reverse tapering process, which increases the diameter of the heated area by 3% to compensate for the change in fiber diameter; Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 35 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%. Example

[0033] Remove the coating layer from the heated area of ​​the optical fiber.

[0034] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0035] Before thermal diffusion, a reverse tapering process is performed on the heated area, which increases the diameter of the heated area by 1% to compensate for changes in the fiber diameter. A heating source is used to heat the heated area of ​​the fiber for 40 minutes to perform thermal diffusion treatment.

[0036] Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 25 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%. Example

[0037] Remove the coating layer from the heated area of ​​the optical fiber.

[0038] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0039] Before thermal diffusion, a reverse tapering process is performed on the heated area, which increases the diameter of the heated area by 2% to compensate for changes in the fiber diameter. A heating source is used to heat the heated area of ​​the fiber for 60 minutes to perform thermal diffusion treatment.

[0040] Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 30 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%. Example

[0041] Remove the coating layer from the heated area of ​​the optical fiber.

[0042] The optical fiber is clamped on both sides of the heating area using a rotating clamping platform. Then, a constant tension is applied to straighten the area between the two clamping points, causing the optical fiber to rotate at a constant speed.

[0043] Before thermal diffusion, a reverse tapering process is performed on the heated area, which increases the diameter of the heated area by 3% to compensate for changes in the fiber diameter. A heating source is used to heat the heated area of ​​the fiber for 80 minutes to perform thermal diffusion treatment.

[0044] Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to 35 μm, the ellipticity was greater than 99%, and the eccentricity generated during the thermal diffusion process was less than 1%.

[0045] Comparative Example 1: Remove the coating layer from the heated area of ​​the optical fiber.

[0046] The optical fiber is clamped on both sides of the heating area using a non-rotating clamping platform, and then a constant tension is applied to straighten the area between the two clamping points.

[0047] A heating source is used to heat the heating area of ​​the optical fiber for 60 minutes to perform thermal diffusion treatment on the optical fiber.

[0048] Finally, the desired thermally diffused fiber was obtained, in which the mode field was diffused from 10.5 μm to an average of about 30 μm, the ellipticity was less than 90%, and the eccentricity generated during the thermal diffusion process was 4%.

[0049] By comparing Examples 1 to 6 with Comparative Example 1, it can be seen that the thermally diffusing optical fiber prepared by this manufacturing method has the characteristics of highly symmetrical mode field expansion, stable fiber diameter, and avoidance of eccentricity problems.

[0050] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a heat-diffusion optical fiber, characterized in that: Includes the following steps: Remove the coating layer from the heated area of ​​the optical fiber; The optical fiber is clamped on both sides of the heating area using a rotating clamping platform, a constant tension is applied, and the optical fiber is rotated at a uniform speed. A heating source is used to heat the heating area of ​​the optical fiber to perform thermal diffusion treatment on the optical fiber; Before or after thermal diffusion, the heated area is subjected to a tapered process to compensate for changes in fiber diameter.

2. The method for manufacturing thermally diffusing optical fiber according to claim 1, characterized in that: The length of the coating removed is 15–30 mm.

3. The method for manufacturing thermally diffusing optical fiber according to claim 1, characterized in that: The rotating clamping platform drives the optical fiber to rotate at a speed greater than 10 revolutions per minute.

4. The method for manufacturing thermally diffusing optical fiber according to claim 1, characterized in that: The heating source is an oxyhydrogen flame, and the heating temperature is at least 1000°C.

5. The method for manufacturing thermally diffusing optical fiber according to claim 4, characterized in that: The heating source moves back and forth along the orientation of the optical fiber heating region at a speed of 2 to 5 mm / s.

6. The method for manufacturing a heat-diffusion optical fiber according to claim 1, characterized in that: The inverted tapering process increases the fiber diameter by 1%-3%.

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