A punching method of panda-type polarization maintaining optical fiber high-stress single-mode preform

Abstract

The present application relates to the field of optical fiber and its manufacturing technology, and discloses a punching method of panda polarization maintaining optical fiber high stress single mode preform rod. The punching method comprises sequentially using a first drill, a second drill, a third drill, a fourth drill, a fifth drill and a sixth drill to punch the single mode preform rod, and placing the single mode preform rod for more than or equal to 5 minutes after the first drill, the second drill, the third drill, the fourth drill and the fifth drill complete the punching, so as to obtain the panda polarization maintaining optical fiber high stress single mode preform rod. By limiting the replacement of the drill during the punching process, controlling the diameter of the drill at the same punching depth, and limiting the placing time after the punching, the internal stress of the single mode preform rod during the punching can be released in time, the problem that the single mode preform rod is prone to cracks is solved, and the punching success rate of the single mode preform rod is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of optical fiber and its manufacturing technology, and in particular to a drilling method for a high-stress single-mode preform of a panda-type polarization-maintaining optical fiber. Background Technology

[0002] Polarization-maintaining fiber, also known as polarization-preserving fiber, is used to transmit linearly polarized light. When linearly polarized light is coupled into a polarization-maintaining fiber, if the polarization direction of the linearly polarized light coincides with the principal axis of polarization of the fiber, the linearly polarized light can maintain its linear polarization direction during transmission until it leaves the fiber. This is the birefringence phenomenon of polarization-maintaining fiber. Many factors can cause birefringence in optical fibers; geometric and stress inhomogeneities can both introduce birefringence. Stress-induced birefringence polarization-maintaining fibers mainly include bow-tie polarization-maintaining fibers, panda polarization-maintaining fibers, and elliptical-clad polarization-maintaining fibers.

[0003] Panda-type polarization-maintaining fiber is one of the most common fiber structures for polarization-maintaining fibers. Stress is applied to the fiber core by circular boron-doped regions on both sides, creating different stresses along two perpendicular directions, thus achieving birefringence and polarization-maintaining characteristics. Currently, to achieve a panda-type fiber structure, holes need to be drilled symmetrically on both sides of the core of a single-mode preform. Boron-doped stress rods are inserted into these holes, and the assembled fiber preform is then drawn into fiber, ultimately resulting in the panda-type polarization-maintaining fiber. Therefore, to achieve higher birefringence, the hole diameter needs to be increased and the hole spacing decreased during drilling, resulting in the drilling position being closer to the core. However, the core material of single-mode preforms is often germanium-doped silicon dioxide. When the germanium doping concentration is high, residual stress remains near the core after annealing. When the drilling position is close to the core, cracks can easily form within the single-mode preform, thus reducing the drilling success rate. Therefore, providing a drilling method for high-stress single-mode preforms of panda-type polarization-maintaining optical fibers is of great significance for improving the drilling success rate. Summary of the Invention

[0004] To address the low drilling success rate of panda-type polarization-maintaining fiber high-stress single-mode preforms in existing technologies, this invention provides a drilling method for panda-type polarization-maintaining fiber high-stress single-mode preforms.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] The first aspect of this invention provides a method for drilling holes in a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, comprising the following steps:

[0007] Step a: Move the first drill bit outward along the core of the single-mold preform and start drilling from the surface of the single-mold preform at a feed rate of 5 mm / min-11 mm / min. When the drilling depth reaches 1 / 4-1 / 3 of the length of the single-mold preform, stop drilling and place for ≥5 min to obtain the first processed single-mold preform.

[0008] Step b: Replace the first drill bit with the second drill bit, and align the axis of the drill core of the second drill bit with the axis of the drill core of the hole drilled in step a. Start drilling from the surface of the first processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the first processed single-mold preform, stop drilling and place for ≥5 min to obtain the second processed single-mold preform.

[0009] Step c: Replace the second drill bit with the third drill bit, align the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b, and start drilling from the surface of the second processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth reaches 2 / 3-3 / 4 of the length of the second processed single-mold preform, stop drilling and place for ≥5 min to obtain the third processed single-mold preform.

[0010] Step d: Replace the third drill bit with the fourth drill bit, align the axis of the drill core of the fourth drill bit with the axis of the drill core of the hole drilled in step c, and start drilling from the surface of the three-processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the third-processed single-mold preform, stop drilling and place for ≥5 min to obtain the fourth-processed single-mold preform.

[0011] Step e: Replace the fourth drill bit with the fifth drill bit, align the axis of the drill core of the fifth drill bit with the axis of the core of the hole drilled in step d, and start drilling from the surface of the fourth-processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth reaches 5 / 6-6 / 7 of the length of the fourth-processed single-mold preform, stop drilling and place for ≥5 min to obtain the fifth-processed single-mold preform.

[0012] Step f: Replace the fifth drill bit with the sixth drill bit, align the axis of the drill core of the sixth drill bit with the axis of the core of the hole drilled in step e, and start drilling from the surface of the fifth-processed single-mode preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the fifth-processed single-mode preform, stop drilling to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0013] Wherein, the diameter of the first drill bit is smaller than the diameter of the second drill bit, the diameter of the second drill bit is larger than the diameter of the third drill bit, the diameter of the third drill bit is smaller than the diameter of the fourth drill bit, the diameter of the fourth drill bit is larger than the diameter of the fifth drill bit, and the diameter of the fifth drill bit is smaller than the diameter of the sixth drill bit.

[0014] Compared to existing technologies, the drilling method for high-stress single-mode preforms of panda-type polarization-maintaining optical fibers provided by this invention avoids the hole cracking problem caused by drill bit instability when using only a single drill bit by changing the drill bit during the drilling process. This invention also limits the placement time after drilling, enabling timely release of internal stress in the processed single-mode preform and additional stress generated during drilling, thereby improving the drilling success rate. Furthermore, by limiting drilling to the same depth using a small-diameter drill bit first, followed by a large-diameter drill bit, the impact force on the core of the single-mode preform during drilling is reduced, preventing core cracking. By limiting drill bit changes during drilling, controlling the drill bit diameter at the same drilling depth, and limiting the placement time after drilling, this invention can timely release the internal stress in the single-mode preform during drilling, solving the problem of easy cracking in single-mode preforms and greatly improving the drilling success rate.

[0015] Preferably, in step a, a hole is first drilled on one side of the single-mode preform, and then, with the core of the single-mode preform as the center of symmetry, the first drill bit is moved to the symmetrical position of the single-mode preform to perform the same drilling operation. Step bf repeats the same operation process as step a above, to obtain a panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0016] More preferably, the diameters of the first drill bit, the third drill bit, and the fifth drill bit are equal.

[0017] More preferably, the diameters of the second drill bit, the fourth drill bit, and the sixth drill bit are equal.

[0018] More preferably, the ratio of the diameter of the first drill bit to the diameter of the second drill bit is 1:(1.05-1.1).

[0019] By limiting the diameter ratio of the first drill bit and the second drill bit, it is beneficial to further release the internal stress of the single-mold preform, thereby improving the drilling success rate.

[0020] More preferably, the diameter ratio of the second drill bit to the diameter of the single-mold preform is 1:(2.6-3.6).

[0021] Preferably, the distance difference between the core of the first drill bit and the core of the single-mold preform is 1:(4.4-4.8) to the diameter of the single-mold preform.

[0022] Preferably, in step a, the ratio of the core diameter of the single-mold preform to the diameter of the single-mold preform is 1:(13-17).

[0023] Preferably, in step a, the refractive index of the core of the single-mode preform is higher than that of the quartz cladding.

[0024] Preferably, in step a, the refractive index difference between the core and the quartz cladding of the single-mold preform is 0.01-0.02. By limiting the parameters of the single-mold preform, it is beneficial to further improve the drilling success rate.

[0025] In a preferred embodiment, the diameter of the single-mold preform is 35mm-50mm.

[0026] Preferably, in step a, the spindle direction of the first drill bit is consistent with the spindle direction of the single-mold preform.

[0027] Preferably, in step a, the rotational speed of the first drill bit is 1700rpm-2600rpm.

[0028] Preferably, in step a, the ultrasonic frequency of the first drill bit is 27000Hz-29000Hz.

[0029] Preferably, in step b, the rotational speed of the second drill bit is 1700rpm-2600rpm.

[0030] Preferably, in step b, the ultrasonic frequency of the second drill bit is 27000Hz-29000Hz.

[0031] Preferably, in step c, the rotation speed of the third drill bit is 1700rpm-2600rpm.

[0032] Preferably, in step c, the ultrasonic frequency of the third drill bit is 27000Hz-29000Hz.

[0033] Preferably, in step d, the rotational speed of the fourth drill bit is 1700rpm-2600rpm.

[0034] Preferably, in step d, the ultrasonic frequency of the fourth drill bit is 27000Hz-29000Hz.

[0035] Preferably, in step e, the rotational speed of the fifth drill bit is 1700rpm-2600rpm.

[0036] Preferably, in step e, the ultrasonic frequency of the fifth drill bit is 27000Hz-29000Hz.

[0037] Preferably, in step f, the rotational speed of the sixth drill bit is 1700rpm-2600rpm.

[0038] Preferably, in step f, the ultrasonic frequency of the sixth drill bit is 27000Hz-29000Hz;

[0039] In steps a-e, the placement time is 5-10 minutes.

[0040] It should be noted that in step f, after the drilling is completed, the bottom of the un-drilled part of the processed single-mode preform is cut off with a rod cutting machine, and the end face is polished to a smooth surface to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0041] This invention addresses the problem of cracking in single-mold preforms by limiting the number of drill bits to be changed during the drilling process, controlling the diameter of the drill bits at the same drilling depth, and limiting the placement time after drilling. This significantly improves the drilling success rate of single-mold preforms. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0043] Example 1

[0044] This embodiment provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, comprising the following steps:

[0045] Step a: Clamp a 300mm long, 50mm diameter single-mold preform onto the drilling machine's worktable. Adjust the orientation of the single-mold preform to align with the spindle direction. Move the first drill bit (18.3mm diameter) horizontally outward along the core of the single-mold preform until the distance between the drill core and the core of the single-mold preform is 10.4mm. Set the rotation speed of the first drill bit to 1700rpm, the ultrasonic frequency to 27000Hz, and the feed rate to 11mm / min. Drilling begins at a speed starting from the surface of the single-mold preform. When the drilling depth reaches 1 / 4 of the single-mold preform, drilling stops. Using the core of the single-mold preform as the center of symmetry, the first drill bit is moved horizontally to the symmetrical position of the single-mold preform and the same drilling operation is performed. After 5 minutes, the first processed single-mold preform is obtained. The ratio of the core diameter to the diameter of the single-mold preform is 1:13, and the refractive index of the core is 0.0124 higher than that of the quartz cladding.

[0046] Step b: Replace the first drill bit with a second drill bit with a diameter of 19.2 mm. Align the axis of the drill core of the second drill bit with the axis of the hole core in step a. Set the rotation speed of the second drill bit to 1700 rpm and the ultrasonic frequency to 27000 Hz. Start drilling from the surface of the first processed single-mold preform at a feed speed of 11 mm / min. Stop drilling when the drilling depth reaches 1 / 4 of the first processed single-mold preform. Using the core of the first processed single-mold preform as the center of symmetry, move the second drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Place for 10 minutes to obtain the second processed single-mold preform.

[0047] Step c: Replace the second drill bit with the third drill bit, aligning the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b. Set the rotation speed of the third drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the second processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 3 / 4 of the second processed single-mold preform. Using the core of the second processed single-mold preform as the center of symmetry, move the third drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it stand for 5 minutes to obtain the third processed single-mold preform. The diameter of the third drill bit is equal to the diameter of the first drill bit.

[0048] Step d: Replace the third drill bit with the fourth drill bit, aligning the axis of the fourth drill bit's core with the axis of the hole core drilled in step c. Set the rotation speed of the fourth drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the three-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 3 / 4 of the third-processed single-mold preform. Using the core of the third-processed single-mold preform as the center of symmetry, move the fourth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it sit for 5 minutes to obtain the fourth-processed single-mold preform. The diameter of the fourth drill bit is equal to the diameter of the second drill bit.

[0049] Step e: Replace the fourth drill bit with the fifth drill bit, align the axis of the fifth drill bit's core with the axis of the hole core drilled in step d, set the rotation speed of the fifth drill bit to 1700 rpm, the ultrasonic frequency to 27000 Hz, and start drilling from the surface of the four-processed single-mold preform at a feed rate of 11 mm / min. When the drilling depth reaches 6 / 7 of the fourth-processed single-mold preform, stop drilling. Using the core of the fourth-processed single-mold preform as the center of symmetry, move the fifth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it stand for 10 minutes to obtain the fifth-processed single-mold preform; wherein, the diameter of the fifth drill bit is equal to the diameter of the first drill bit;

[0050] Step f: Replace the fifth drill bit with the sixth drill bit, aligning the axis of the sixth drill bit's core with the axis of the hole core drilled in step e. Set the rotation speed of the sixth drill bit to 1700 rpm and the ultrasonic frequency to 27000 Hz. Start drilling from the surface of the fifth-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 6 / 7 of the fifth-processed single-mold preform. Using the core of the fifth-processed single-mold preform as the center of symmetry, move the sixth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the sixth-processed single-mold preform. The diameter of the sixth drill bit is equal to the diameter of the second drill bit.

[0051] Step g: Use a rod cutting machine to cut off the bottom of the un-drilled single-mode preform after processing, and polish the end face until smooth to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0052] Example 2

[0053] This embodiment provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, comprising the following steps:

[0054] Step a: Clamp a 300mm long, 35mm diameter single-mold preform on the drilling machine worktable. Adjust the direction of the single-mold preform to be consistent with the spindle direction. Move the first drill bit (8.8mm diameter) horizontally outward along the core of the single-mold preform until the distance between the core of the first drill bit and the core of the single-mold preform is 8.0mm. Set the rotation speed of the first drill bit to 2600rpm, the ultrasonic frequency to 29000Hz, and the feed rate to 5mm / min. Drilling begins at a speed starting from the surface of the single-mold preform. When the drilling depth reaches 1 / 3 of the single-mold preform, drilling stops. Using the core of the single-mold preform as the center of symmetry, the first drill bit is moved horizontally to the symmetrical position of the single-mold preform and the same drilling operation is performed. After 10 minutes, the first processed single-mold preform is obtained. The ratio of the core diameter to the diameter of the single-mold preform is 1:17, and the refractive index of the core is 0.0147 higher than that of the quartz cladding.

[0055] Step b: Replace the first drill bit with a second drill bit with a diameter of 9.7 mm. Align the axis of the drill core of the second drill bit with the axis of the hole core in step a. Set the rotation speed of the second drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the first processed single-mold preform at a feed speed of 5 mm / min. Stop drilling when the drilling depth reaches 1 / 3 of the first processed single-mold preform. Using the core of the first processed single-mold preform as the center of symmetry, move the second drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Place for 5 minutes to obtain the second processed single-mold preform.

[0056] Step c: Replace the second drill bit with the third drill bit, aligning the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b. Set the rotation speed of the third drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the second processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 2 / 3 of the second processed single-mold preform. Using the core of the second processed single-mold preform as the center of symmetry, move the third drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it stand for 10 minutes to obtain the third processed single-mold preform. The diameter of the third drill bit is equal to the diameter of the first drill bit.

[0057] Step d: Replace the third drill bit with the fourth drill bit, aligning the axis of the fourth drill bit's core with the axis of the hole core drilled in step c. Set the rotation speed of the fourth drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the three-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 2 / 3 of the third-processed single-mold preform. Using the core of the third-processed single-mold preform as the center of symmetry, move the fourth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it stand for 10 minutes to obtain the fourth-processed single-mold preform. The diameter of the fourth drill bit is equal to the diameter of the second drill bit.

[0058] Step e: Replace the fourth drill bit with the fifth drill bit, align the axis of the fifth drill bit's core with the axis of the hole core drilled in step d, set the rotation speed of the fifth drill bit to 2600 rpm, the ultrasonic frequency to 29000 Hz, and start drilling from the surface of the four-processed single-mold preform at a feed rate of 5 mm / min. When the drilling depth reaches 5 / 6 of the fourth-processed single-mold preform, stop drilling. Using the core of the fourth-processed single-mold preform as the center of symmetry, move the fifth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it sit for 5 minutes to obtain the fifth-processed single-mold preform; wherein, the diameter of the fifth drill bit is equal to the diameter of the first drill bit;

[0059] Step f: Replace the fifth drill bit with the sixth drill bit, aligning the axis of the sixth drill bit's core with the axis of the hole core drilled in step e. Set the rotation speed of the sixth drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the fifth-processed single-mold preform at a feed rate of 5 mm / min. Stop drilling when the drilling depth reaches 5 / 6 of the fifth-processed single-mold preform. Using the core of the fifth-processed single-mold preform as the center of symmetry, move the sixth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the sixth-processed single-mold preform. The diameter of the sixth drill bit is equal to the diameter of the second drill bit.

[0060] Step g: Use a rod cutting machine to cut off the bottom of the un-drilled single-mode preform after processing, and polish the end face until smooth to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0061] Example 3

[0062] This embodiment provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, comprising the following steps:

[0063] Step a: Clamp a 300mm long, 40mm diameter single-mold preform onto the drilling machine's worktable. Adjust the direction of the single-mold preform to align with the spindle direction. Move the first drill bit (12.5mm diameter) horizontally outward along the core of the single-mold preform until the distance between the drill core and the core of the single-mold preform is 8.7mm. Set the rotation speed of the first drill bit to 2000rpm, the ultrasonic frequency to 28000Hz, and the feed rate to 8mm / min. Drilling begins at a speed starting from the surface of the single-mold preform. When the drilling depth reaches 1 / 3 of the single-mold preform, drilling stops. Using the core of the single-mold preform as the center of symmetry, the first drill bit is moved horizontally to the symmetrical position of the single-mold preform and the same drilling operation is performed. After 6 minutes, the first processed single-mold preform is obtained. The ratio of the core diameter to the diameter of the single-mold preform is 1:15, and the refractive index of the core is 0.0173 higher than that of the quartz cladding.

[0064] Step b: Replace the first drill bit with a second drill bit with a diameter of 13.3 mm. Align the axis of the drill core of the second drill bit with the axis of the hole core in step a. Set the rotation speed of the second drill bit to 2100 rpm and the ultrasonic frequency to 27900 Hz. Start drilling from the surface of the first processed single-mold preform at a feed speed of 10 mm / min. Stop drilling when the drilling depth reaches 1 / 3 of the first processed single-mold preform. Using the core of the first processed single-mold preform as the center of symmetry, move the second drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Place for 7 minutes to obtain the second processed single-mold preform.

[0065] Step c: Replace the second drill bit with the third drill bit, aligning the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b. Set the rotation speed of the third drill bit to 2460 rpm and the ultrasonic frequency to 28500 Hz. Start drilling from the surface of the second processed single-mold preform at a feed rate of 9 mm / min. Stop drilling when the drilling depth reaches 2 / 3 of the second processed single-mold preform. Using the core of the second processed single-mold preform as the center of symmetry, move the third drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it stand for 7 minutes to obtain the third processed single-mold preform. The diameter of the third drill bit is equal to the diameter of the first drill bit.

[0066] Step d: Replace the third drill bit with the fourth drill bit, aligning the axis of the fourth drill bit's core with the axis of the hole core drilled in step c. Set the rotation speed of the fourth drill bit to 2300 rpm and the ultrasonic frequency to 27800 Hz. Start drilling from the surface of the three-processed single-mold preform at a feed rate of 8 mm / min. Stop drilling when the drilling depth reaches 2 / 3 of the third-processed single-mold preform. Using the core of the third-processed single-mold preform as the center of symmetry, move the fourth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it sit for 9 minutes to obtain the fourth-processed single-mold preform. The diameter of the fourth drill bit is equal to the diameter of the second drill bit.

[0067] Step e: Replace the fourth drill bit with the fifth drill bit, aligning the axis of the fifth drill bit's core with the axis of the hole core drilled in step d. Set the rotation speed of the fifth drill bit to 1800 rpm and the ultrasonic frequency to 27690 Hz. Start drilling from the surface of the four-processed single-mold preform at a feed rate of 6 mm / min. Stop drilling when the drilling depth reaches 5 / 6 of the fourth-processed single-mold preform. Using the core of the fourth-processed single-mold preform as the center of symmetry, move the fifth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation. Let it sit for 6 minutes to obtain the fifth-processed single-mold preform. The diameter of the fifth drill bit is equal to the diameter of the first drill bit.

[0068] Step f: Replace the fifth drill bit with the sixth drill bit, aligning the axis of the sixth drill bit's core with the axis of the hole core drilled in step e. Set the rotation speed of the sixth drill bit to 1800 rpm and the ultrasonic frequency to 27690 Hz. Start drilling from the surface of the fifth-processed single-mold preform at a feed rate of 6 mm / min. Stop drilling when the drilling depth reaches 5 / 6 of the fifth-processed single-mold preform. Using the core of the fifth-processed single-mold preform as the center of symmetry, move the sixth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the sixth-processed single-mold preform. The diameter of the sixth drill bit is equal to the diameter of the second drill bit.

[0069] Step g: Use a rod cutting machine to cut off the bottom of the un-drilled single-mode preform after processing, and polish the end face until smooth to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0070] Example 4

[0071] This embodiment provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Embodiment 1 in that:

[0072] The ratio of the diameter of the first drill bit to the diameter of the second drill bit is 1:1.3;

[0073] The other operating steps are the same as in Example 1.

[0074] Example 5

[0075] This embodiment provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Embodiment 1 in that:

[0076] The distance between the drill core of the first drill bit and the core of the single-mold precast rod is 11.6 mm;

[0077] The other operating steps are the same as in Example 1.

[0078] Comparative Example 1

[0079] This comparative example provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Example 1 in that:

[0080] In step a, the drilling depth is 1 / 2 of the length of the single-mold preform;

[0081] In step b, the drilling depth is to reach 1 / 2 of the length of the first single-mold preform.

[0082] The other operating steps are the same as in Example 1.

[0083] Comparative Example 2

[0084] This comparative example provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Example 1 in that:

[0085] In step e, the drilling depth reaches 41 / 42 of the length of the fourth processing single-mold preform;

[0086] In step f, the drilling depth reaches 41 / 42 of the length of the fifth-processed single-mold preform;

[0087] The other operating steps are the same as in Example 1.

[0088] Comparative Example 3

[0089] This comparative example provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Example 1 in that:

[0090] In steps a-e, after stopping drilling, let it sit for 3 minutes;

[0091] The other operating steps are the same as in Example 1.

[0092] Comparative Example 4

[0093] This comparative example provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Example 1 in that:

[0094] In step a, the drilling depth is 1 / 4 of the length of the single-mold preform;

[0095] In step b, the drilling depth is 1 / 3 of the length of the first single-mold preform.

[0096] The other operating steps are the same as in Example 1.

[0097] Comparative Example 5

[0098] This comparative example provides a drilling method for a high-stress single-mode preform of a panda-shaped polarization-maintaining optical fiber, which differs from Example 1 in that:

[0099] Step a: Clamp a 300mm long, 50mm diameter single-mold preform onto the drilling machine's worktable. Adjust the direction of the single-mold preform to align with the spindle direction. Move the first drill bit (18.3mm diameter) outward along the core of the single-mold preform until the distance between the core of the first drill bit and the core of the single-mold preform is 10.4mm. Set the rotation speed of the first drill bit to 1700rpm and the ultrasonic frequency to 27000Hz, at a speed of 11mm / min. The feed rate n starts drilling from the surface of the single-mold preform. When the drilling depth reaches 1 / 4 of the single-mold preform, the drilling stops. With the core of the single-mold preform as the center of symmetry, the first drill bit is moved horizontally to the symmetrical position of the single-mold preform and the same drilling operation is performed to obtain the first processed single-mold preform. The ratio of the core diameter to the diameter of the single-mold preform is 1:13, and the refractive index of the core is 0.0124 higher than that of the quartz cladding.

[0100] Step b: Replace the first drill bit with a second drill bit with a diameter of 19.2 mm. Align the axis of the drill core of the second drill bit with the axis of the hole core in step a. Set the rotation speed of the second drill bit to 1700 rpm and the ultrasonic frequency to 27000 Hz. Start drilling from the surface of the first processed single-mold preform at a feed speed of 11 mm / min. Stop drilling when the drilling depth reaches 1 / 4 of the first processed single-mold preform. Using the core of the first processed single-mold preform as the center of symmetry, move the second drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the second processed single-mold preform.

[0101] Step c: Replace the second drill bit with the third drill bit, aligning the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b. Set the rotation speed of the third drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the second-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 3 / 4 of the second-processed single-mold preform. Using the core of the second-processed single-mold preform as the center of symmetry, move the third drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the third-processed single-mold preform. The diameter of the third drill bit is equal to the diameter of the first drill bit.

[0102] Step d: Replace the third drill bit with a fourth drill bit, aligning the axis of the fourth drill bit's core with the axis of the hole core drilled in step c. Set the rotation speed of the fourth drill bit to 2600 rpm and the ultrasonic frequency to 29000 Hz. Start drilling from the surface of the three-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 3 / 4 of the third-processed single-mold preform. Using the core of the third-processed single-mold preform as the center of symmetry, move the fourth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the fourth-processed single-mold preform. The diameter of the fourth drill bit is equal to the diameter of the second drill bit.

[0103] Step e: Replace the fourth drill bit with the fifth drill bit, align the axis of the fifth drill bit's core with the axis of the hole core drilled in step d, set the rotation speed of the fifth drill bit to 1700 rpm, the ultrasonic frequency to 27000 Hz, and start drilling from the surface of the four-processed single-mold preform at a feed rate of 11 mm / min. When the drilling depth reaches 6 / 7 of the fourth-processed single-mold preform, stop drilling. Using the core of the fourth-processed single-mold preform as the center of symmetry, move the fifth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the fifth-processed single-mold preform; wherein, the diameter of the fifth drill bit is equal to the diameter of the first drill bit;

[0104] Step f: Replace the fifth drill bit with the sixth drill bit, aligning the axis of the sixth drill bit's core with the axis of the hole core drilled in step e. Set the rotation speed of the sixth drill bit to 1700 rpm and the ultrasonic frequency to 27000 Hz. Start drilling from the surface of the fifth-processed single-mold preform at a feed rate of 11 mm / min. Stop drilling when the drilling depth reaches 6 / 7 of the fifth-processed single-mold preform. Using the core of the fifth-processed single-mold preform as the center of symmetry, move the sixth drill bit horizontally to the symmetrical position of the single-mold preform and perform the same drilling operation to obtain the sixth-processed single-mold preform. The diameter of the sixth drill bit is equal to the diameter of the second drill bit.

[0105] Step g: Use a rod cutting machine to cut off the bottom of the un-drilled single-mode preform after processing, and polish the end face until smooth to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform.

[0106] The other operating steps are the same as in Example 1.

[0107] Repeated experiments were conducted on the panda-shaped polarization-maintaining fiber high-stress single-mode preforms prepared in Examples 1-5 and Comparative Examples 1-5, and the drilling success rate was statistically analyzed. The results are shown in Table 1.

[0108] Table 1

[0109]

[0110]

[0111] As can be seen from Table 1 of this invention, the drilling success rate of the panda-shaped polarization-maintaining fiber high-stress single-mode preform prepared using the drilling method of this embodiment is as high as 99%, while the drilling success rate of the panda-shaped polarization-maintaining fiber high-stress single-mode preform prepared using the drilling method provided in the comparative example is all below 75%. Furthermore, analysis of the preforms that failed to be drilled showed large-area cracks, and even led to cracking of the preform body. It is evident that the drilling method for the panda-shaped polarization-maintaining fiber high-stress single-mode preform provided by this invention can effectively solve the problem of easy cracking in single-mode preforms and greatly improve the drilling success rate of single-mode preforms.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drilling method for a panda-shaped polarization-maintaining optical fiber high-stress single-mode preform, characterized in that, Includes the following steps: Step a: Move the first drill bit outward along the core of the single-mold preform and start drilling from the surface of the single-mold preform at a feed rate of 5 mm / min-11 mm / min. When the drilling depth reaches 1 / 4-1 / 3 of the length of the single-mold preform, stop drilling and place for ≥5 min to obtain the first processed single-mold preform. Step b: Replace the first drill bit with the second drill bit, and align the axis of the drill core of the second drill bit with the axis of the drill core of the hole drilled in step a. Start drilling from the surface of the first processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the first processed single-mold preform, stop drilling and place for ≥5 min to obtain the second processed single-mold preform. Step c: Replace the second drill bit with the third drill bit, align the axis of the drill core of the third drill bit with the axis of the drill core of the hole drilled in step b, and start drilling from the surface of the second processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth reaches 2 / 3-3 / 4 of the length of the second processed single-mold preform, stop drilling and place for ≥5 min to obtain the third processed single-mold preform. Step d: Replace the third drill bit with the fourth drill bit, align the axis of the drill core of the fourth drill bit with the axis of the drill core of the hole drilled in step c, and start drilling from the surface of the third processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the third processed single-mold preform, stop drilling and place for ≥5 min to obtain the fourth processed single-mold preform. Step e: Replace the fourth drill bit with the fifth drill bit, align the axis of the drill core of the fifth drill bit with the axis of the core of the hole drilled in step d, and start drilling from the surface of the fourth processed single-mold preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth reaches 5 / 6-6 / 7 of the length of the fourth processed single-mold preform, stop drilling and place for ≥5 min to obtain the fifth processed single-mold preform. Step f: Replace the fifth drill bit with the sixth drill bit, align the axis of the drill core of the sixth drill bit with the axis of the core of the hole drilled in step e, and start drilling from the surface of the fifth processed single-mode preform at a feed speed of 5 mm / min-11 mm / min. When the drilling depth is the same as the drilling depth of the fifth processed single-mode preform, stop drilling to obtain the panda-shaped polarization-maintaining fiber high-stress single-mode preform. Wherein, the diameter of the first drill bit is smaller than the diameter of the second drill bit, the diameter of the second drill bit is larger than the diameter of the third drill bit, the diameter of the third drill bit is smaller than the diameter of the fourth drill bit, the diameter of the fourth drill bit is larger than the diameter of the fifth drill bit, and the diameter of the fifth drill bit is smaller than the diameter of the sixth drill bit.

2. The drilling method for the panda-type polarization-maintaining fiber high-stress single-mode preform as described in claim 1, characterized in that, The diameters of the first drill bit, the third drill bit, and the fifth drill bit are equal; and / or The diameters of the second drill bit, the fourth drill bit, and the sixth drill bit are equal.

3. The drilling method for the high-stress single-mode preform of panda-type polarization-maintaining optical fiber as described in claim 1, characterized in that, The diameter ratio of the first drill bit to the diameter of the second drill bit is 1:(1.05-1.1); and / or The ratio of the diameter of the second drill bit to the diameter of the single-mold preform is 1:(2.6-3.6).

4. The drilling method for the high-stress single-mode preform of panda-type polarization-maintaining optical fiber as described in claim 1, characterized in that, The distance difference between the drill core of the first drill bit and the core of the single-mold preform is given by a ratio of 1:(4.4-4.8) to the diameter of the single-mold preform; and / or In step a, the ratio of the core diameter of the single-mold preform to the diameter of the single-mold preform is 1:(13-17).

5. The drilling method for the panda-type polarization-maintaining fiber high-stress single-mode preform as described in claim 1, characterized in that, In step a, the rotational speed of the first drill bit is 1700 rpm-2600 rpm; and / or In step a, the ultrasonic frequency of the first drill bit is 27000Hz-29000Hz.

6. The drilling method for the high-stress single-mode preform of panda-type polarization-maintaining optical fiber as described in claim 1, characterized in that, In step b, the rotational speed of the second drill bit is 1700 rpm-2600 rpm; and / or In step b, the ultrasonic frequency of the second drill bit is 27000Hz-29000Hz.

7. The drilling method for the panda-type polarization-maintaining fiber high-stress single-mode preform as described in claim 1, characterized in that, In step c, the rotational speed of the third drill bit is 1700 rpm-2600 rpm; and / or In step c, the ultrasonic frequency of the third drill bit is 27000Hz-29000Hz.

8. The drilling method for the high-stress single-mode preform of panda-type polarization-maintaining optical fiber as described in claim 1, characterized in that, In step d, the rotational speed of the fourth drill bit is 1700 rpm-2600 rpm; and / or In step d, the ultrasonic frequency of the fourth drill bit is 27000Hz-29000Hz.

9. The drilling method for the panda-type polarization-maintaining fiber high-stress single-mode preform as described in claim 1, characterized in that, In step e, the rotational speed of the fifth drill bit is 1700 rpm-2600 rpm; and / or In step e, the ultrasonic frequency of the fifth drill bit is 27000Hz-29000Hz.

10. The drilling method for the panda-type polarization-maintaining fiber high-stress single-mode preform as described in claim 1, characterized in that, In step f, the rotational speed of the sixth drill bit is 1700 rpm-2600 rpm; and / or In step f, the ultrasonic frequency of the sixth drill bit is 27000Hz-29000Hz; and / or In steps a-e, the placement time is 5-10 minutes.

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