Multi-core optical fiber preform rod capable of positioning fiber core and preparation method of multi-core optical fiber preform rod

Abstract

The invention provides a multi-core optical fiber preform capable of positioning a fiber core and a preparation method thereof, and relates to the technical field of preparation of special optical fibers, and the preparation method comprises the following steps: forming a positioning hole in a quartz mother rod along the axial direction, and installing a positioning core rod in the positioning hole; performing rod shrinkage on the quartz mother rod provided with the positioning core rod to obtain a solid positioning core mother rod; a core rod hole is formed in the solid positioning core mother rod, a transmission core rod is installed in the core rod hole, and the multi-core optical fiber preform rod capable of positioning the fiber core is obtained. According to the preparation method of the multi-core optical fiber preform capable of positioning the fiber core, provided by the invention, the positioning hole is firstly formed, the positioning core rod is mounted in the positioning hole, and the positioning hole and the positioning core rod are attached in a rod shrinkage manner, so that a larger opening aperture can be obtained when the positioning hole is formed; therefore, the difficulty of processing the deep hole in the high-purity quartz rod is reduced. Meanwhile, the diameter of a core rod hole capable of being formed is enlarged, and the diameter range of a transmission core rod capable of being mounted in the multi-core optical fiber preform rod capable of positioning the fiber core is enlarged.

Description

Technical Field

[0001] The invention relates to the technical field of special optical fiber preparation, and in particular to a multi-core optical fiber preform rod with positionable fiber cores and a preparation method thereof. Background Art

[0002] Traditional single-mode optical fibers are now unable to meet the requirements of high-speed data transmission. Multi-core optical fibers have multiple cores in the same cladding, which can more directly increase the optical fiber transmission channel, thereby improving the overall transmission capacity. Multiple cores share the same cladding, and the number of optical fibers used to achieve the same effect is reduced, which can significantly reduce costs, reduce the use of space, and improve economic benefits. The simultaneous transmission of multiple cores can also provide backup for signal light and improve the reliability of the line. At the same time, when transmitting the same power signal light, the number of optical fibers required is reduced, and the complexity of making the corresponding equipment and devices will be greatly reduced. Doping rare earth elements in the core can provide additional amplification for the transmitted signal light.

[0003] Multi-core optical fiber has a complex structure. To ensure the stability and reliability of its application, higher requirements are placed on the optical fiber preparation process. In some special applications, different fiber cores can also be customized to achieve different functions. This requires marking the fiber cores for easy identification during application.

[0004] In the prior art, the preparation of multi-core preform rods generally adopts the drilling method to drill the holes of the positioning core and the active fiber core at the same time. However, the conventional drilling of high-purity quartz rods has high requirements for the quartz rods, and there are certain restrictions on the distance between the hole for the positioning core and the hole for the active fiber core. If the distance is too close, it will affect the shape of the fiber core, and if the hole is too large, it will be impossible to arrange the hole for the active fiber core. Therefore, the diameter of the hole for the positioning core is limited. On the basis of only being able to drill small holes, it is more difficult to process deep holes on the quartz rod. Summary of the invention

[0005] The invention provides a method for preparing a multi-core optical fiber preform rod with positionable fiber cores, which is used to solve the defect that it is more difficult to process deep holes on a quartz rod in the prior art.

[0006] A method for preparing a multi-core optical fiber preform with positionable cores according to the present invention comprises: Prepare quartz master rod, positioning mandrel rod and transmission mandrel rod; A positioning hole is formed in the quartz mother rod along the axial direction, and the positioning core rod is installed in the positioning hole; Shrinking the quartz mother rod on which the positioning core rod is installed to obtain a solid positioning core mother rod; A core rod hole is opened on the solid positioning core mother rod, and the transmission core rod is installed in the core rod hole to obtain a multi-core optical fiber preform rod with positioning cores.

[0007] According to a method for preparing a multi-core optical fiber preform rod with positionable cores provided by the present invention, the aperture of the positioning hole is x, the diameter of the positioning core rod is c, and 0≤xc≤0.2mm.

[0008] According to a method for preparing a multi-core optical fiber preform with a positionable core provided by the present invention, the step of shrinking the quartz mother rod equipped with the positioning core rod comprises: evacuating the positioning hole, heating the quartz mother rod equipped with the positioning core rod to a specified temperature, and melting and shrinking the positioning core rod inside the quartz mother rod.

[0009] According to a method for preparing a multi-core optical fiber preform with positionable cores provided by the present invention, the specified temperature is 2000°C-2300°C.

[0010] According to a method for preparing a multi-core optical fiber preform rod with positionable cores provided by the present invention, before the core rod hole is opened, the solid positioning core mother rod is rounded.

[0011] According to a method for preparing a multi-core optical fiber preform with positionable cores provided by the present invention, the preparation method further comprises: Prepare a balancing rod, wherein the material of the balancing rod is the same as that of the quartz mother rod, and the size of the balancing rod is the same as that of the positioning core rod; When opening the positioning holes, at least one balancing hole is opened axially on the quartz mother rod, and the balancing rod is installed in each balancing hole. The balancing hole has the same size as the positioning hole and is symmetrically distributed with the positioning hole, and the center of the quartz mother rod is the center of symmetry.

[0012] According to a method for preparing a multi-core optical fiber preform with positionable cores provided by the present invention, the transmission core rod is a rare earth doped core rod.

[0013] According to a method for preparing a multi-core optical fiber preform rod with positionable cores provided by the present invention, the positioning core rod is a fluorine-doped quartz glass rod.

[0014] The present invention also provides a multi-core optical fiber preform with a positionable core, which is prepared by the method for preparing a multi-core optical fiber preform with a positionable core as described in any of the above embodiments.

[0015] The present invention provides a method for preparing a multi-core optical fiber preform with a positionable core, which first opens a positioning hole and installs a positioning core rod in the positioning hole, and fits the positioning hole and the positioning core rod by shrinking the rod, so that a larger opening diameter can be obtained when the positioning hole is opened, thereby reducing the difficulty of processing deep holes on high-purity quartz rods. At the same time, the diameter of the core rod hole that can be opened is expanded, and the diameter range of the transmission core rod that can be installed in the multi-core optical fiber preform with a positionable core is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention is a schematic flow chart of a method for preparing a multi-core optical fiber preform with positionable cores.

[0018] Figure 2 It is a schematic structural diagram of a multi-core optical fiber preform rod with positionable cores according to the present invention.

[0019] Figure 3 It is a schematic diagram of the connection relationship between the quartz mother rod and the positioning core rod of the present invention.

[0020] Figure 4 It is a schematic diagram of the connection relationship between the positioning core rod and the balance rod on the quartz mother rod of the present invention.

[0021] Figure 5 It is a schematic diagram of the structural relationship when the present invention is shrinking the rod.

[0022] Reference numerals: 1. Quartz mother rod; 11. Positioning hole; 12. Balancing hole; 2. Positioning mandrel; 3. Transmission mandrel; 4. Mandrel hole; 5. Balancing rod; 6. Heat source. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The features of the terms "first" and "second" in the specification and claims of the present invention may include one or more of the features explicitly or implicitly. In the description of the present invention, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects associated before and after are in an "or" relationship.

[0025] In the description of the present invention, it needs to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0026] Combine the following Figure 1-Figure 5 The method for preparing a multi-core optical fiber preform with positionable cores of the present invention is described.

[0027] like Figure 1 , Figure 2 As shown, the present invention provides a method for preparing a multi-core optical fiber preform with positionable cores, comprising the following steps: S1. Prepare a quartz mother rod 1, a positioning core rod 2 and a transmission core rod 3.

[0028] S2, a positioning hole 11 is opened in the quartz mother rod 1 along the axial direction, and the positioning core rod 2 is installed in the positioning hole 11.

[0029] S3, shrinking the quartz mother rod 1 equipped with the positioning core rod 2 to obtain a solid positioning core mother rod.

[0030] S4, a core rod hole 4 is opened on the solid positioning core mother rod, and the transmission core rod 3 is installed in the core rod hole 4 to obtain a multi-core optical fiber preform rod with a positioning core.

[0031] Specifically, a high-purity quartz rod is selected as the quartz mother rod 1 for processing, and a pure quartz glass rod and a pure quartz glass sleeve can also be combined and thermally melted to form the quartz mother rod 1. The aperture of the positioning hole 11 is x, and the diameter of the positioning core rod 2 is c, 0≤xc≤0.2mm.

[0032] Specifically, the positioning hole 11 is opened separately from the core rod hole 4, and after the positioning core rod 2 is installed, the positioning hole 11 is shrunk by shrinking the rod so that the positioning hole 11 fits the positioning core rod 2. Figure 3 As shown, a1 is a positional relationship diagram between the positioning hole 11 and the quartz mother rod 1 before the positioning core rod 2 is installed, and a2 is a structural schematic diagram of the solid positioning core mother rod. Since the positioning hole 11 can be shrunk in step S3, the positioning hole 11 can obtain a larger opening diameter when it is opened. When opening the core rod hole 4, the positioning core rod 2 can support the side wall between the core rod hole 4 and the positioning hole 11, reducing the risk of hole wall cracking caused by the small hole spacing between the core rod hole 4 and the positioning hole 11 when drilling the core rod hole 4, thereby allowing a smaller gap to be set between the core rod hole 4 and the positioning hole 11, and expanding the diameter of the core rod hole 4 that can be opened. This allows more margin to be obtained when opening the positioning hole 11 and the core rod hole 4.

[0033] The present invention provides a method for preparing a multi-core optical fiber preform with a positionable core, by first opening a positioning hole 11 and installing a positioning core rod 2 in the positioning hole 11, and fitting the positioning hole 11 with the positioning core rod 2 by shrinking the rod, so that a larger opening aperture can be obtained when the positioning hole 11 is opened, thereby reducing the difficulty of processing a deep hole on a high-purity quartz rod. At the same time, the diameter of the core rod hole 4 that can be opened is expanded, and the diameter range of the transmission core rod 3 that can be installed in the multi-core optical fiber preform with a positionable core is increased.

[0034] In some embodiments, the step of shrinking the quartz mother rod 1 with the positioning core rod 2 installed includes: evacuating the positioning hole 11, heating the quartz mother rod 1 with the positioning core rod 2 installed to a specified temperature, and causing the positioning core rod 2 to melt and shrink inside the quartz mother rod 1.

[0035] Further, the specified temperature is 2000°C-2300°C.

[0036] Specifically, when shrinking the rod, Figure 5 As shown, by sealing one end of the positioning hole 11 and connecting the other end to a quartz extension tube for vacuuming, the pressure in the positioning hole 11 is controlled at -600mbar ~ -700mbar, and at the same time, the quartz mother rod 1 equipped with the positioning core rod 2 is rotated, and the speed is controlled to be 30rpm-40rpm. At a temperature of 2000℃ to 2300℃, the heated heat source 6 is reciprocated along the axial direction of the quartz mother rod 1, and the quartz mother rod 1 equipped with the positioning core rod 2 is melted and shrunk to form a solid positioning core mother rod. The heat source 6 uses a hydrogen-oxygen flame, and the moving speed of the heat source 6 is 12-16mm / min, so that the heating is more uniform and the out-of-roundness of the solid positioning core mother rod after heat shrinkage is reduced.

[0037] In an optional embodiment, the preparation method further comprises: before opening the core rod hole 4, rounding the solid positioning core mother rod.

[0038] Specifically, since the positioning hole 11 is set as a single one and is located at an eccentric position of the quartz mother rod 1, although the positioning core rod 2 is closely spaced from the positioning hole 11, a certain amount of non-circularity will still be introduced, affecting the subsequent drilling accuracy. By rounding the solid positioning core mother rod, that is, polishing the outer circle of the solid positioning core mother rod, the dimensional symmetry in the diameter direction is ensured. Fine-tuning and correcting the outer circle boundary can make the overall roundness of the optical fiber higher, reduce the fusion loss when fusion-splicing with other device pigtails, and improve the transmission efficiency.

[0039] In some other optional embodiments, the preparation method further includes: preparing a balancing rod 5, the material of the balancing rod 5 is the same as the material of the quartz mother rod 1, and the size of the balancing rod 5 is the same as the size of the positioning core rod 2. When the positioning hole 11 is opened, at least one balancing hole 12 is opened axially on the quartz mother rod 1, and the balancing rod 5 is installed in each balancing hole 12. The balancing holes 12 are the same size as the positioning holes 11 and are symmetrically distributed with the positioning holes 11, and the center of the circle of the quartz mother rod 1 is the center of symmetry.

[0040] Specifically, this embodiment provides another solution to the out-of-roundness of the solid positioning core mother rod caused by the shrinking of the rod. Figure 4 As shown, b1 is a schematic diagram of the positional relationship between the balancing hole 12 and the positioning hole 11 when the balancing rod 5 and the positioning core rod 2 are not installed, and b2 is a schematic diagram of the structure of the solid positioning core mother rod when the balancing rod 5 and the positioning core rod 2 are installed. By opening a balancing hole 12 with the same size as the positioning hole 11 on the quartz mother rod 1, the balancing hole 12 and the positioning hole 11 are centrally symmetrically distributed, and the center of the circle of the quartz mother rod 1 is the center of symmetry. Of course, multiple balancing holes 12 can also be opened, and the balancing holes 12 and the positioning holes 11 are rotationally symmetrically distributed, and the center of the circle of the quartz mother rod 1 is the center of symmetry. While the positioning core rod 2 is installed in the positioning hole 11, the balancing rods 5 are installed in the balancing holes 12 one by one. The positioning holes 11 and the balancing holes 12 are melted and shrunk together when the rods are shrunk, so that the size shrinkage caused by the melting and shrinking is evenly distributed on the outer circle of the quartz mother rod 1, thereby reducing the out-of-roundness of the mother rod caused by the shrinking of the rod. Afterwards, the remaining mandrel holes 4 are opened according to the angle distance between the positioning core and the centers of the other mandrel holes 4, and the transmission mandrel 3 is assembled without the need for grinding operations.

[0041] In some optional embodiments, the transmission core rod 3 is a rare earth doped core rod.

[0042] Specifically, the transmission core rod 3 is set as a rare earth doped core rod, and the rare earth doped core rod is prepared by MCVD equipment, and the rare earth element doped in the transmission core rod 3 includes one or a combination of erbium and ytterbium elements. The doped rare earth elements such as erbium and ytterbium can play an additional amplification role under the action of pump light.

[0043] Specifically, when MCVD prepares a transmission core rod 3, a sunken cladding is constructed on the outer wall of the transmission core rod 3, and the refractive index of the sunken cladding is lower than the refractive index of the transmission core rod 3 and the quartz mother rod 1 to prevent interference between different fiber cores during signal light transmission, thereby affecting the stability of the transmission mode.

[0044] In some optional embodiments, the positioning core rod 2 is a fluorine-doped quartz glass rod. The numerical aperture of the fluorine layer of the positioning core rod 2 is 0.06-0.18.

[0045] Specifically, a fluorine-doped core rod is prepared by MCVD or PCVD, and the fluorine layer has a numerical aperture (NA) between 0.06 and 0.18. The refractive index of the positioning core rod 2 is different from that of the quartz mother rod 1. The outer glass layer is polished to be 0.2 mm smaller than the diameter of the positioning hole 11, and then placed in the above-mentioned drilled quartz rod after cleaning.

[0046] In some optional embodiments, the step of opening a core rod hole 4 on a solid positioning core mother rod comprises: marking and locating the center position of the core rod hole 4 on the solid positioning core mother rod based on the relative position of the positioning core rod 2 on the quartz mother rod 1, and opening the core rod hole 4 axially on the solid positioning core mother rod according to the center position obtained by the marking and locating.

[0047] Specifically, a coordinate plane system is constructed on the end face of the quartz mother rod 1 with the center of the quartz mother rod 1 as the origin and the direction of the line connecting the center of the quartz mother rod 1 to the center of the positioning core as the positive direction of the Y axis, so that the coordinates of the center of each core rod hole 4 can be marked and positioned on the end face of the quartz mother rod 1, and the core rod hole 4 is drilled axially on the solid positioning core mother rod according to the center position obtained by marking and positioning.

[0048] Specifically, at least two mandrel holes 4 are provided and are symmetrically distributed, the transmission mandrel 3 is installed one by one with the mandrel holes 4, and α<180° / N, wherein α is the angle between the line connecting the center of the positioning core and the center of the quartz mother rod 1 and the center of the near-positioning mandrel and the center of the quartz mother rod 1, the near-positioning mandrel is the transmission mandrel 3 closest to the positioning core, and N is the number of the mandrel holes 4. Preferably, α<160° / N.

[0049] In a specific embodiment, as shown in the figure, the number of core rod holes 4 is 4 and they are symmetrically distributed. The radius of the quartz mother rod 1 is R, the diameter of the core rod hole 4 is d, the minimum side hole spacing between the outer circle of the quartz mother rod 1 and the core rod hole 4 is b, and α is less than 40°. The center of the quartz mother rod 1 is taken as the origin (0, 0), the coordinates of the point A closest to the outer circle of the positioning core rod 2 and the quartz mother rod 1 are (0, R), the coordinates of point B are (Rsinα, Rcosα), the core rod hole 4 closest to the positioning core is position 1, and positions 2, 3, and 4 are defined clockwise, the center of position 1 is ((Rb-)sinα, (Rbd / 2)cosα), the center of position 3 is (-(Rbd / 2)sinα, -(Rbd / 2)cosα), the center of position 2 is ((Rbd / 2)cosα, -(Rbd / 2)sinα), and the center of position 4 is (-(Rbd / 2)cosα, (Rbd / 2)sinα). According to the coordinates of positions 1, 2, 3, and 4, the core rod hole 4 is opened on the quartz mother rod 1.

[0050] The present invention also provides a multi-core optical fiber preform with a positionable core, which is prepared by the method for preparing a multi-core optical fiber preform with a positionable core in any of the above embodiments. The multi-core optical fiber preform with a positionable core prepared by the method in any of the above embodiments can be drawn and coated to prepare a multi-core optical fiber with a positionable core.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a multi-core optical fiber preform with positionable cores, characterized in that: include: Prepare quartz master rod, positioning mandrel rod and transmission mandrel rod; A positioning hole is formed in the quartz mother rod along the axial direction, and the positioning core rod is installed in the positioning hole; Shrinking the quartz mother rod on which the positioning core rod is installed to obtain a solid positioning core mother rod; A core rod hole is opened on the solid positioning core mother rod, and the transmission core rod is installed in the core rod hole to obtain a multi-core optical fiber preform rod with positioning cores.

2. The method for preparing a multi-core optical fiber preform with positionable cores according to claim 1, characterized in that: The aperture of the positioning hole is x, the diameter of the positioning core rod is c, and 0≤xc≤0.2mm.

3. The method for preparing a multi-core optical fiber preform with positionable cores according to claim 1, characterized in that: The step of shrinking the quartz mother rod with the positioning core rod installed includes: evacuating the positioning hole, heating the quartz mother rod with the positioning core rod installed to a specified temperature, and melting and shrinking the positioning core rod in the quartz mother rod.

4. The method for preparing a multi-core optical fiber preform with positionable cores according to claim 3, wherein the specified temperature is 2000°C-2300°C.

5. The method for preparing a multi-core optical fiber preform with positionable cores according to claim 1, characterized in that: The preparation method further comprises: before opening the core rod hole, rounding the solid positioning core mother rod.

6. The method for preparing a multi-core optical fiber preform with positionable cores according to claim 1, characterized in that: The preparation method further comprises: Prepare a balancing rod, wherein the material of the balancing rod is the same as that of the quartz mother rod, and the size of the balancing rod is the same as that of the positioning core rod; When opening the positioning holes, at least one balancing hole is opened axially on the quartz mother rod, and the balancing rod is installed in each balancing hole. The balancing hole has the same size as the positioning hole and is symmetrically distributed with the positioning hole, and the center of the quartz mother rod is the center of symmetry.

7. The method for preparing a multi-core optical fiber preform with positionable cores according to any one of claims 1 to 6, characterized in that: The transmission core rod is a rare earth doped core rod.

8. The method for preparing a multi-core optical fiber preform with positionable cores according to any one of claims 1 to 6, characterized in that: The positioning core rod is a fluorine-doped quartz glass rod.

9. The method for preparing a multi-core optical fiber preform with positionable cores according to any one of claims 1 to 6, characterized in that: The step of opening a core rod hole on the solid positioning core mother rod comprises: Based on the relative position of the positioning core rod on the quartz mother rod, the center position of the core rod hole is marked and positioned on the solid positioning core mother rod, and a core rod hole is opened axially on the solid positioning core mother rod according to the center position obtained by marking and positioning.

10. A multi-core optical fiber preform with positionable cores, characterized in that: The multi-core optical fiber preform with a positionable core is prepared by the method for preparing a multi-core optical fiber preform with a positionable core as described in any one of claims 1-9.

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