Seven-core six-mode optical fiber fan-in and fan-out device and preparation method thereof

Abstract

The invention relates to the technical field of optical fiber communication, in particular to a seven-core six-mode optical fiber fan-in and fan-out device and a preparation method thereof.The seven-core six-mode optical fiber fan-in and fan-out device comprises a target quartz glass sleeve which is integrally conical, the outer layer of the target quartz glass sleeve is a common quartz layer, the inner layer of the target quartz glass sleeve is a fluorine-doped quartz layer, and seven hole units in the middle of the inner layer are tangent in pairs and arranged in a plum blossom shape to form a plum blossom-shaped hole; the optical fiber bundle is composed of seven single-core six-mode optical fibers which are subjected to cladding corrosion by a corrosion solution, and the seven single-core six-mode optical fibers are arranged in a hexagonal manner and are gathered together; the optical fiber bundle is arranged in the quincunx hole of the target quartz glass sleeve; and the ground end face of any end of the seven-core six-mode optical fiber is welded with the ground end face of one end of the optical fiber bundle, the cladding of which is corroded by the corrosion solution. The fan-in / fan-out optical fiber device prepared by the invention has the advantages of lower insertion loss, small crosstalk between modes, high mode demultiplexing efficiency, convenience in cutting and welding, and easiness in realizing large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of optical fiber communication technology, and in particular to a seven-core six-mode optical fiber fan-in and fan-out device and a preparation method thereof. Background Art

[0002] With the commercialization of 5G technology (fifth-generation mobile communication technology) and the rapid development of the Internet of Things and smart cities, the demand for data transmission in communication networks is increasing. In 5G, lower frequency bands are used, and the channel capacity is mainly increased by multiple-input multiple-output technology (MIMO) and non-orthogonal multiple access technology (NOMA). However, traditional single-core single-mode optical fiber is close to the limit of its communication capacity, and there is an urgent need to expand the capacity of optical communication systems. Although time division multiplexing (TDM), wavelength division multiplexing (WDM), polarization multiplexing (PDM) and other methods have been used to increase the capacity of the system in single-mode optical fiber (SMF) optical transmission systems, due to the rapid growth of digital data services, the bandwidth density of single-mode optical fiber can no longer meet the existing high demand.

[0003] Multi-core fiber is an innovative fiber. Different from conventional single-core fiber, it integrates multiple cores in the same cladding. Each core acts as an independent transmission path and can transmit optical signals independently. This design enables multi-core fiber to transmit multiple signals at the same time, greatly improving the transmission efficiency of the fiber. Compared with the signal attenuation and dispersion problems faced by traditional single-core fiber in long-distance transmission, multi-core fiber effectively solves this problem through its multi-core structure, while significantly increasing the transmission capacity, thus meeting the existing high demand.

[0004] The fan-in / fan-out technology of multi-core fiber is specifically used to handle the input and output of optical signals for each core in a multi-core fiber, which is usually referred to as fan-in and fan-out. Fan-out devices usually need to be produced in pairs, and their insertion loss and return loss also need to be tested in pairs. They are then cut and processed according to the user's specific needs, such as the required length, sleeve type, and connector type. One end of the fan-out device is connected to the multi-core fiber and the other end is connected to the single-mode fiber. It can be customized according to the multi-core type used by the user, and the number of cores supported can be 2 to 22.

[0005] At present, scientists have conducted a lot of research on fan-in / fan-out devices: Chinese patent CN218728145U proposes a method for making a fan-in / fan-out device by using a sleeve to gather multiple single-core optical fibers. The method is simple to operate, but the optical fiber bundle is only fixed by a circular sleeve and adhesive, and the optical fiber is not corroded, so that the multi-core optical fiber needs to have a large core distance and a large cladding diameter, which has higher requirements for the preparation process; Chinese patent CN115542462A proposes a fan-in / fan-out device, which is prepared by chemically corroding the optical fiber cladding and then combining it with a fluorine-doped quartz glass sleeve, but it is difficult to achieve precise alignment of the cores when docking with a multi-core optical fiber using an ordinary fluorine-doped quartz glass sleeve; Japanese patent GB201712495A proposes using a single-mode optical fiber bundle with a groove structure to dock with a multi-core optical fiber to make a seven-core fan-in / fan-out device, but it is difficult to ensure that the fiber cores are neatly arranged in the bundled optical fiber bundle, and the physical bundling method may increase the insertion loss and Fresnel reflection.

[0006] In summary, in the existing multi-core optical fiber fan-in / fan-out devices, the center of the sleeve is mostly a circular hole, and glue or filler is required between the optical fiber bundle composed of multiple single-core optical fibers and the sleeve, which makes the arrangement of the fiber cores easy to change during the preparation process, and there is a problem that the sleeve and the multi-core optical fiber cannot be accurately aligned when they are connected; the existing multi-core optical fiber fan-in / fan-out device preparation method is difficult to obtain regularly arranged fiber cores, resulting in excessive insertion loss and strong Fresnel reflection problems, and it is difficult to achieve accurate alignment of the cores when the sleeve and the multi-core optical fiber are connected, resulting in excessive fusion loss and crosstalk, as well as difficulties in cutting and fusion. Summary of the invention

[0007] To this end, the technical problem to be solved by the present invention is to overcome the problem that glue or filler is required between the optical fiber bundle composed of multiple single-core optical fibers in the multi-core optical fiber fan-in / fan-out device in the prior art and the sleeve, which causes the arrangement of the optical cores to change easily during the preparation process, and there is a problem that the sleeve and the multi-core optical fiber cannot be accurately aligned when they are connected; the multi-core optical fiber fan-in / fan-out device preparation method in the prior art is difficult to obtain regularly arranged optical cores, there are problems of large insertion loss and Fresnel reflection, it is difficult to achieve accurate alignment of the cores when the sleeve and the multi-core optical fiber are connected, there are problems of excessive fusion loss and crosstalk, and there are difficulties in cutting and fusion.

[0008] In order to solve the above technical problems, the present invention provides a seven-core six-mode fan-in fan-out device, comprising:

[0009] The target quartz glass sleeve is tapered as a whole, with an outer layer of ordinary quartz and an inner layer of fluorine-doped quartz, and a plum blossom-shaped hole is formed in the middle of the inner layer by seven hole units that are tangent to each other in a plum blossom shape;

[0010] An optical fiber bundle, which is composed of seven single-core six-mode optical fibers whose claddings are corroded by a corrosive solution, arranged in a hexagon and gathered together; the optical fiber bundle is placed in the plum blossom-shaped hole of the target quartz glass sleeve;

[0011] A seven-core six-mode optical fiber has its end surface polished at any end fused with the end surface polished at one end of the optical fiber bundle whose cladding has been corroded by a corrosive solution.

[0012] Preferably, the outer diameter of the outer layer of the target quartz glass sleeve is in the range of 300.0 to 1000.0 μm; the outer diameter of the inner layer of the target quartz glass sleeve is in the range of 90 to 500 μm.

[0013] Preferably, the drilling diameter of each hole unit of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 60.0 to 240.0 μm; the inner diameter major axis range of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 180.0 to 720.0 μm; the inner diameter minor axis range of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 100.0 to 416.0 μm; the inner diameter peak distance range of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 50.0 to 210.0 μm.

[0014] Preferably, the relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a preset wavelength ranges from -0.0030 to -0.0010; wherein the preset wavelength is 1550 nm.

[0015] Preferably, the duty cycle of the target quartz glass sleeve is in the range of 0.40 to 0.80.

[0016] Preferably, seven single-core six-mode optical fibers and one seven-core six-mode optical fiber both support LP 01 LP 11a LP 11b LP 21a LP 21b LP 02 Six modes of transmission.

[0017] The present invention also provides a method for preparing a seven-core six-mode fan-in fan-out device, which is applied to prepare the above-mentioned seven-core six-mode fan-in fan-out device, comprising:

[0018] Prepare a target quartz glass sleeve; wherein the target quartz glass sleeve is conical, the outer layer is a common quartz layer, the inner layer is a fluorine-doped quartz layer, and there is a plum blossom-shaped hole in the middle of the inner layer;

[0019] Each single-core six-mode optical fiber is corroded to obtain each single-core six-mode optical fiber after the corrosion is completed; each single-core six-mode optical fiber after the corrosion is completed is gathered into an optical fiber bundle by a hexagonal arrangement; one end of the optical fiber bundle after the cladding is corroded is inserted into the target quartz glass sleeve along the front end of the taper of the target quartz glass sleeve to obtain the target quartz glass sleeve inserted into the optical fiber bundle;

[0020] Grind the end face of the target quartz glass sleeve inserted into the optical fiber bundle and the end face of the seven-core six-mode optical fiber to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle and the ground seven-core six-mode optical fiber; connect seven light sources to one end of the optical fiber bundle, and connect an optical power meter to one end of the seven-core six-mode optical fiber; align the central axis corresponding to the tapered rear end face of the ground target quartz glass sleeve inserted into the optical fiber bundle with the central axis corresponding to the ground seven-core six-mode optical fiber, and then rotate until the optical power output by the optical power meter is the maximum, stop rotating, and perform welding at the current alignment position to obtain a completed fan-in fan-out device;

[0021] The manufactured fan-in fan-out device is packaged in a fiber optic box.

[0022] Preferably, the step of preparing the target quartz glass sleeve comprises:

[0023] A quincunx-shaped hole capillary preform is prepared, and the quincunx-shaped hole capillary preform is cleaned and put into a drawing tower for drawing to obtain a quincunx-shaped hole fluorine-doped quartz glass sleeve;

[0024] The fluorine-doped quartz glass sleeve with a plum blossom-shaped hole is tapered to obtain a target quartz glass sleeve; wherein the target quartz glass sleeve is tapered, the outer layer is a common quartz layer, the inner layer is a fluorine-doped quartz layer, and there is a plum blossom-shaped hole in the middle of the inner layer.

[0025] Preferably, the step of corroding each single-core six-mode optical fiber to obtain each single-core six-mode optical fiber after corrosion comprises:

[0026] The coating layer at one end of each single-core six-mode optical fiber is removed, and the optical fiber is cleaned with a dust-free paper towel containing alcohol to obtain each cleaned single-core six-mode optical fiber;

[0027] Putting each cleaned single-core six-mode optical fiber into a corrosion solution of a first concentration for rapid dissolution and then cleaning to obtain each cleaned single-core six-mode optical fiber;

[0028] Put each cleaned single-core six-mode optical fiber into a corrosion solution of the second concentration and slowly dissolve it until the centerline inner diameter of each single-core six-mode optical fiber approaches a preset target value, thereby obtaining each single-core six-mode optical fiber after preliminary corrosion;

[0029] After the initial corrosion, each single-core six-mode optical fiber is again placed in the corrosion solution of the second concentration for dissolution, and taken out once every preset time, and the current diameter of each single-core six-mode optical fiber is measured until each single-core six-mode optical fiber is corroded to the preset diameter, thereby obtaining each single-core six-mode optical fiber after the corrosion is completed;

[0030] Wherein, the corrosion solution is a hydrofluoric acid solution; the first concentration is 40%; the second concentration is 20%; and the preset time is 5 minutes.

[0031] Preferably, the step of grinding the end face of the target quartz glass sleeve inserted into the optical fiber bundle and the end face of the seven-core six-mode optical fiber to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle and the ground seven-core six-mode optical fiber comprises:

[0032] The target quartz glass sleeve inserted into the optical fiber bundle is inserted into the ceramic tube, and the ceramic head is ground. After the grinding is completed, the ceramic tube is removed to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle; the seven-core six-mode optical fiber is ground to obtain the ground seven-core six-mode optical fiber.

[0033] The above technical solution of the present invention has the following beneficial effects compared with the prior art:

[0034] In the seven-core six-mode fan-in and fan-out device described in the present invention, the inner layer of the target quartz glass sleeve used is a fluorine-doped quartz layer, so that the refractive index difference between the sleeve and the optical fiber is increased, the light limiting ability of the optical fiber is enhanced, and the crosstalk between different optical fibers is reduced; at the same time, the middle of the inner layer of the target quartz glass sleeve used is a plum blossom-shaped hole, and no filler is required to connect the optical fiber bundle and the plum blossom-shaped hole, and the deviation range of each single-core optical fiber from its corresponding punching position is less than 0.1μm, so that a plurality of single-core optical fibers can be arranged regularly;

[0035] The method for preparing a seven-core six-mode fan-in fan-out device of the present invention comprises preparing a target quartz glass sleeve whose inner layer is a fluorine-doped quartz layer and whose middle part is a quincunx-shaped hole, so that the prepared seven-core six-mode fan-in fan-out device has strong rigidity and is convenient for cutting and welding; a plurality of single-core optical fibers are corroded and then arranged in a hexagonal shape to form an optical fiber bundle, and then the optical fiber bundle is inserted into the sleeve, so that a regularly arranged optical fiber bundle can be obtained, which lays a foundation for the subsequent precise alignment of the cores when the sleeve is connected to the multi-core optical fiber, and at the same time reduces the insertion loss and the welding loss in the preparation process. consumption; seven light sources are connected to one end of the optical fiber bundle, and an optical power meter is connected to one end of the seven-core six-mode optical fiber. When the optical power output by the optical power meter is the largest, fusion splicing is performed at the position where the central axis corresponding to the rear end face of the taper of the target quartz glass sleeve inserted into the optical fiber bundle after grinding is aligned with the central axis corresponding to the grinded seven-core six-mode optical fiber, so that the cores can be accurately aligned when the sleeve is connected to the multi-core optical fiber; in addition, the preparation method is simple and easy to realize large-scale production, and the ability to prepare fan-in and fan-out devices with higher core regular arrangement can be increased according to demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0037] Figure 1 It is a schematic diagram of a seven-core six-mode fan-in fan-out device provided by the present invention;

[0038] Figure 2 It is a flow chart of a method for preparing a seven-core six-mode fan-in fan-out device provided by the present invention;

[0039] Figure 3 is a schematic diagram of the target quartz glass sleeve;

[0040] Figure 4 is a schematic diagram of the front and rear end surfaces of the tapered target quartz glass sleeve; Figure 4 (a) is a schematic diagram showing the front end surface of the tapered quartz glass sleeve of the target; Figure 4 (b) is a schematic diagram showing the tapered rear end surface of the target quartz glass sleeve;

[0041] Figure 5 It is a schematic diagram of the corrosion process of a single-core optical fiber;

[0042] Figure 6 is a schematic diagram of the end face of the target quartz glass sleeve into which the optical fiber bundle is inserted;

[0043] Figure 7 This is a schematic diagram of the end face of a general sleeve after it is inserted into the optical fiber bundle;

[0044] Explanation of the reference numerals in the specification: 1. ordinary quartz layer; 2. fluorine-doped quartz layer; 3. quincunx hole; 4. single-core six-mode optical fiber core; 5. cladding of single-core six-mode optical fiber; 6. hydrofluoric acid solution used for etching the cladding; 7. air; 8. glue; D1 is the outer diameter of the outer layer in the target quartz glass sleeve; D2 is the outer diameter of the inner layer in the target quartz glass sleeve; d is the punching diameter of each hole unit of the quincunx hole in the target quartz glass sleeve; L1 is the inner diameter major axis of the quincunx hole in the target quartz glass sleeve; L2 is the inner diameter minor axis of the quincunx hole in the target quartz glass sleeve; L3 is the inner diameter peak distance of the quincunx hole in the target quartz glass sleeve. DETAILED DESCRIPTION

[0045] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0046] At present, the application of multi-core optical fiber in various fields, including high-capacity data transmission, connection between data centers, distributed sensor networks, and optical network construction, is gradually expanding. With the continuous advancement of communication technology, multi-core optical fiber will play a more critical role in future optical communication systems.

[0047] Hexamode fiber is a fiber that supports a limited number of propagation modes and has some unique performance characteristics that allow the inclusion of the fundamental propagation mode (LP 01 ) and the first higher order mode (LP 11 ) and other modes of propagation; this type of optical fiber is particularly suitable for high-capacity optical communication systems due to its lower dispersion characteristics, higher frequency capacity and wider bandwidth; in addition, six-mode optical fiber is also suitable for application scenarios that require fine manipulation and modulation of optical signals.

[0048] Based on the existing research, the existing technology is still insufficient in meeting the technical requirements for space-division multiplexing devices in large-capacity space-division multiplexing optical fiber communication systems. Therefore, in view of the actual application requirements of mode multiplexing technology in the next generation optical fiber communication system, the present invention provides a technology for preparing multi-core optical fiber fan-in / fan-out devices using a quincunx-shaped hole fluorine-doped quartz glass sleeve, which can solve the problem of difficulty in obtaining regular arrangement of optical fibers when preparing multi-core optical fiber fan-in / fan-out devices, and reduce the insertion loss, crosstalk and difficulties in cutting and welding of the prepared devices.

[0049] Reference Figure 1 As shown, Figure 1 A schematic diagram of a seven-core six-mode fan-in fan-out device provided by the present invention; specifically comprising:

[0050] The target quartz glass sleeve is tapered as a whole, with an outer layer of ordinary quartz and an inner layer of fluorine-doped quartz, and a plum blossom-shaped hole is formed in the middle of the inner layer by seven hole units that are tangent to each other in a plum blossom shape;

[0051] The outer diameter of the outer layer of the target quartz glass sleeve is in the range of 300.0 to 1000.0 μm; the outer diameter of the inner layer of the target quartz glass sleeve is in the range of 90 to 500 μm; the punching diameter of each hole unit of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 60.0 to 240.0 μm; the inner diameter of the quincunx-shaped hole in the target quartz glass sleeve is in the range of 180.0 to 720.0 μm; The inner diameter minor axis range of the flower-shaped hole is 100.0 to 416.0 μm; the inner diameter peak distance range of the quincunx-shaped hole in the target quartz glass sleeve is 50.0 to 210.0 μm; the relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at the preset wavelength ranges from -0.0030 to -0.0010; the preset wavelength is 1550 nm; the duty cycle range of the target quartz glass sleeve is 0.40 to 0.80;

[0052] An optical fiber bundle, which is composed of seven single-core six-mode optical fibers whose claddings are corroded by a corrosive solution, arranged in a hexagon and gathered together; the optical fiber bundle is placed in the plum blossom-shaped hole of the target quartz glass sleeve;

[0053] A seven-core six-mode optical fiber, the polished end face of any end of which is fused with the polished end face of one end of the optical fiber bundle after the cladding is corroded by a corrosive solution;

[0054] Among them, seven single-core six-mode optical fibers and one seven-core six-mode optical fiber both support LP 01 LP 11a LP 11b LP 21a LP 21b LP 02 Six modes of transmission.

[0055] Reference Figure 2 As shown, Figure 2 The present invention provides a flow chart of a method for preparing a seven-core six-mode fan-in fan-out device; the method is applied to prepare the above-mentioned seven-core six-mode fan-in fan-out device, specifically comprising:

[0056] S1: Prepare the target quartz glass sleeve, including:

[0057] A quincunx-shaped hole capillary preform is prepared, and the quincunx-shaped hole capillary preform is washed and placed in a drawing tower for drawing to obtain a quincunx-shaped hole fluorine-doped quartz glass sleeve; wherein, during the drawing process, the drawing temperature, the drawing speed and the speed of feeding the quincunx-shaped hole capillary preform into the drawing tower need to be strictly controlled;

[0058] The fluorine-doped quartz glass sleeve with a plum blossom-shaped hole is tapered to obtain a target quartz glass sleeve; wherein the target quartz glass sleeve is tapered, the outer layer is a common quartz layer, the inner layer is a fluorine-doped quartz layer, and there is a plum blossom-shaped hole in the middle of the inner layer; the target quartz glass sleeve is as follows Figure 3 As shown, the front and rear end surfaces of the taper are as follows Figure 4 As shown in the figure, the front end surface of the taper of the target quartz glass sleeve is as follows Figure 4 As shown in (a) of FIG. 1 ; the rear end surface of the target quartz glass sleeve after taper is as shown in FIG. Figure 4 As shown in (b);

[0059] S2: removing the coating layer at one end of each single-core six-mode optical fiber, and cleaning it with a dust-free paper towel containing alcohol to obtain each cleaned single-core six-mode optical fiber; placing each cleaned single-core six-mode optical fiber in a corrosion solution of a first concentration for rapid dissolution and then cleaning it to obtain each cleaned single-core six-mode optical fiber; placing each cleaned single-core six-mode optical fiber in a corrosion solution of a second concentration for slow dissolution until the inner diameter of the center line of each single-core six-mode optical fiber approaches a preset target value, to obtain each single-core six-mode optical fiber after preliminary corrosion; placing each single-core six-mode optical fiber after preliminary corrosion in a corrosion solution of a second concentration again for dissolution, and taking it out every preset time, measuring the current diameter of each single-core six-mode optical fiber, until each single-core six-mode optical fiber is corroded to a preset diameter, to obtain each single-core six-mode optical fiber after corrosion; wherein, the single-core optical fiber corrosion process is as follows Figure 5 As shown;

[0060] In a specific implementation of the present invention, the etching solution is a hydrofluoric acid solution; the first concentration is 40%; the second concentration is 20%; the preset time is 5 minutes;

[0061] S3: Use a hexagonal arrangement to gather each single-core six-mode optical fiber after etching to form an optical fiber bundle; insert one end of the optical fiber bundle after etching the cladding into the target quartz glass sleeve along the front end of the taper of the target quartz glass sleeve to obtain the target quartz glass sleeve inserted into the optical fiber bundle; wherein the end face of the target quartz glass sleeve inserted into the optical fiber bundle is as follows: Figure 6 As shown;

[0062] in, Figure 6 There is air between each single-core optical fiber, and the deviation range between each single-core optical fiber and its corresponding punching position is less than 0.1μm. Figure 7There is glue between each single-core optical fiber; the inner layer of the target quartz glass sleeve used in the present invention is a fluorine-doped quartz layer, and the middle of the inner layer is a plum blossom-shaped hole. During the preparation process, multiple single-core optical fibers are arranged in a hexagonal shape and gathered to form an optical fiber bundle. There is no need to use glue to stick the multiple single-core optical fibers together, and the core arrangement will not change due to thermal expansion during the taper process. Therefore, the prepared seven-core six-mode fan-in fan-out device can arrange the cores regularly, thereby reducing the insertion loss and fusion loss in the preparation process;

[0063] S4: inserting the target quartz glass sleeve inserted into the optical fiber bundle into the ceramic tube, and grinding the ceramic head, removing the ceramic tube after grinding to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle; grinding the seven-core six-mode optical fiber to obtain the ground seven-core six-mode optical fiber; connecting seven light sources at one end of the optical fiber bundle, and connecting an optical power meter at one end of the seven-core six-mode optical fiber; aligning the central axis corresponding to the rear end face of the tapered end of the ground target quartz glass sleeve inserted into the optical fiber bundle with the central axis corresponding to the ground seven-core six-mode optical fiber, and then rotating until the optical power output by the optical power meter is the maximum, stopping the rotation and fusing at the current alignment position to obtain a completed fan-in and fan-out device; wherein, seven optical power meters are connected to one end of the optical fiber bundle, and one optical power meter is connected to one end of the seven-core six-mode optical fiber;

[0064] S5: Encapsulate the manufactured fan-in fan-out device in a fiber optic box.

[0065] In order to verify that the seven-core six-mode fan-in fan-out device prepared by the present invention is better, the following embodiments are provided, including:

[0066] The relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a wavelength of 1550 nm in the seven-core six-mode optical fiber fan-in / fan-out device provided in Example 1 is -0.0030; the outer diameter of the outer layer in the current target quartz glass sleeve is 1000.0 μm; the outer diameter of the inner layer in the current target quartz glass sleeve is 500.0 μm; the drilling diameter of each hole unit of the plum blossom hole in the current target quartz glass sleeve is 240.0 μm; the seven hole units in the current target quartz glass sleeve are arranged in a plum blossom shape; the inner diameter major axis of the plum blossom hole in the current target quartz glass sleeve is 720.0 μm; the inner diameter minor axis of the plum blossom hole in the current target quartz glass sleeve is 420.0 μm; the inner diameter peak distance of the plum blossom hole in the current target quartz glass sleeve is 210.0 μm; the duty cycle of the current target quartz glass sleeve is 0.40;

[0067] Seven single-core six-mode optical fibers with a diameter of 240.0 μm are sequentially placed in a hydrofluoric acid solution for etching. The seven single-core six-mode optical fibers that have been etched are arranged in a hexagon and gathered to form a fiber bundle, and then inserted into a target quartz glass sleeve. The sleeve is then inserted into a ceramic tube, and then the front of the ceramic head and the end face of the seven-core six-mode optical fiber are ground. The ceramic tube after grinding is removed, and seven light sources are connected to one end of the fiber bundle, and an optical power meter is connected to one end of the seven-core six-mode optical fiber. The target quartz glass sleeve after grinding is aligned with the central axis of the multi-core optical fiber with a diameter of 240.0 μm, and then the optical fiber is rotated, and the output of the optical power meter is recorded. When the output optical power is maximum, fusion splicing is performed to achieve accurate docking between the cores.

[0068] The relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a wavelength of 1550 nm in the seven-core six-mode optical fiber fan-in / fan-out device provided in Example 2 is -0.0010; the outer diameter of the outer layer in the current target quartz glass sleeve is 190.0 μm; the outer diameter of the inner layer in the current target quartz glass sleeve is 90.0 μm; the drilling diameter of each hole unit of the quincunx hole in the current target quartz glass sleeve is 60.0 μm; the seven hole units in the current target quartz glass sleeve are arranged in a quincunx shape; the inner diameter major axis of the quincunx hole in the current target quartz glass sleeve is 180.0 μm; the inner diameter minor axis of the quincunx hole in the current target quartz glass sleeve is 100.0 μm; the inner diameter peak distance of the quincunx hole in the current target quartz glass sleeve is 50.0 μm; the duty cycle of the current target quartz glass sleeve is 0.70;

[0069] Seven single-core six-mode optical fibers with a diameter of 60.0 μm are sequentially placed in a hydrofluoric acid solution for etching. The seven single-core six-mode optical fibers that have been etched are arranged in a hexagon and gathered to form a fiber bundle, and then inserted into a target quartz glass sleeve. The sleeve is then inserted into a ceramic tube, and then the front of the ceramic head and the end face of the seven-core six-mode optical fiber are ground. The ceramic tube after grinding is removed, and seven light sources are connected to one end of the fiber bundle, and an optical power meter is connected to one end of the seven-core six-mode optical fiber. The target quartz glass sleeve after grinding is aligned with the central axis of the multi-core optical fiber with a diameter of 60.0 μm, and then the optical fiber is rotated, and the output of the optical power meter is recorded. When the output optical power is maximum, fusion splicing is performed to achieve accurate docking between the cores.

[0070] The relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a wavelength of 1550 nm in the seven-core six-mode optical fiber fan-in / fan-out device provided in Example 3 is -0.0015; the outer diameter of the outer layer in the current target quartz glass sleeve is 600.0 μm; the outer diameter of the inner layer in the current target quartz glass sleeve is 300.0 μm; the drilling diameter of each hole unit of the quincunx hole in the current target quartz glass sleeve is 170.0 μm; the seven hole units in the current target quartz glass sleeve are arranged in a quincunx shape; the inner diameter major axis of the quincunx hole in the current target quartz glass sleeve is 510.0 μm; the inner diameter minor axis of the quincunx hole in the current target quartz glass sleeve is 300.0 μm; the inner diameter peak distance of the quincunx hole in the current target quartz glass sleeve is 150.0 μm; the duty cycle of the current target quartz glass sleeve is 0.60;

[0071] Seven single-core six-mode optical fibers with a diameter of 170.0 μm are sequentially placed in a hydrofluoric acid solution for etching. The seven single-core six-mode optical fibers that have been etched are arranged in a hexagon and gathered to form a fiber bundle, and then inserted into a target quartz glass sleeve. The sleeve is then inserted into a ceramic tube, and then the front of the ceramic head and the end face of the seven-core six-mode optical fiber are ground. The ceramic tube after grinding is removed, and seven light sources are connected to one end of the fiber bundle, and an optical power meter is connected to one end of the seven-core six-mode optical fiber. The target quartz glass sleeve after grinding is aligned with the central axis of the multi-core optical fiber with a diameter of 170.0 μm, and then the optical fiber is rotated, and the output of the optical power meter is recorded. When the output optical power is maximum, fusion splicing is performed to achieve accurate docking between the cores.

[0072] The main structural parameters of the target quartz glass sleeve in the above embodiments are shown in Table 1.

[0073] Table 1 Main structural parameters of target quartz glass sleeve

[0074]

[0075] The relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a wavelength of 1550 nm in the seven-core six-mode optical fiber fan-in / fan-out device provided in Example 4 is -0.0015; the outer diameter of the outer layer in the current target quartz glass sleeve is 440.0 μm; the outer diameter of the inner layer in the current target quartz glass sleeve is 200.0 μm; the drilling diameter of each hole unit of the quincunx hole in the current target quartz glass sleeve is 125.0 μm; the seven hole units in the current target quartz glass sleeve are arranged in a quincunx shape; the inner diameter major axis of the quincunx hole in the current target quartz glass sleeve is 375.0 μm; the inner diameter minor axis of the quincunx hole in the current target quartz glass sleeve is 220.0 μm; the inner diameter peak distance of the quincunx hole in the current target quartz glass sleeve is 110.0 μm; the duty cycle of the current target quartz glass sleeve is 0.60;

[0076] Seven single-core six-mode optical fibers with a diameter of 125.0 μm are sequentially placed in a hydrofluoric acid solution for etching. The seven single-core six-mode optical fibers that have been etched are arranged in a hexagon and gathered to form a fiber bundle, and then inserted into a target quartz glass sleeve. The sleeve is then inserted into a ceramic tube, and then the front of the ceramic head and the end face of the seven-core six-mode optical fiber are ground. The ceramic tube after grinding is removed, and seven light sources are connected to one end of the fiber bundle, and an optical power meter is connected to one end of the seven-core six-mode optical fiber. The target quartz glass sleeve after grinding is aligned with the central axis of the multi-core optical fiber with a diameter of 125.0 μm, and then the optical fiber is rotated, and the output of the optical power meter is recorded. When the output optical power is maximum, fusion splicing is performed to achieve accurate docking between the cores.

[0077] The insertion loss when making the fan-in / fan-out device in Example 4 is shown in Table 2, and the crosstalk when making the fan-in / fan-out device is shown in Table 3.

[0078] Table 2 Insertion loss of fan-in / fan-out devices

[0079]

[0080] Table 3 Crosstalk of fan-in / fan-out devices

[0081]

[0082] It can be seen from Tables 1 to 3 that the inner layer of the target quartz glass sleeve used in the present invention is a fluorine-doped quartz layer, so that the refractive index difference between the sleeve and the optical fiber is increased, the optical fiber's ability to restrict light is enhanced, and the crosstalk between different optical fibers is reduced, so that the prepared seven-core six-mode fan-in fan-out device has strong rigidity and is convenient for cutting and welding; the inner layer of the target quartz glass sleeve used is a fluorine-doped quartz layer, and the middle of the inner layer is a plum blossom-shaped hole. During the preparation process, multiple single-core optical fibers are arranged in a hexagonal shape and gathered to form an optical fiber bundle. There is no need to use glue to stick the multiple single-core optical fibers together, and the core arrangement will not be affected due to thermal expansion during the taper process. Changes, therefore, the prepared seven-core six-mode fan-in fan-out device can arrange the fiber cores regularly, and the deviation range of each single-core optical fiber and its corresponding punching position is less than 0.1μm, thereby reducing the insertion loss and fusion loss in the preparation process; at the same time, the preparation is simple and easy to realize large-scale production, and the ability to prepare fan-in fan-out devices with higher core regular arrangement can be increased by increasing the number of punchings according to demand; in addition, the seven-core six-mode fan-in / fan-out optical fiber device has low insertion loss, small crosstalk between modes, high mode demultiplexing efficiency, convenient cutting and fusion, easy to realize large-scale production, and has good application prospects in the field of space-division multiplexing optical fiber communication.

[0083] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A seven-core six-mode fan-in fan-out device, characterized in that: include: The target quartz glass sleeve is tapered as a whole, with an outer layer of ordinary quartz and an inner layer of fluorine-doped quartz, and a plum blossom-shaped hole is formed in the middle of the inner layer by seven hole units that are tangent to each other in a plum blossom shape; An optical fiber bundle, which is composed of seven single-core six-mode optical fibers whose claddings are corroded by a corrosive solution, arranged in a hexagon and gathered together; the optical fiber bundle is placed in the plum blossom-shaped hole of the target quartz glass sleeve; A seven-core six-mode optical fiber has its end surface polished at any end fused with the end surface polished at one end of the optical fiber bundle whose cladding has been corroded by a corrosive solution.

2. The seven-core six-mode fan-in fan-out device according to claim 1, characterized in that: The outer diameter of the outer layer of the target quartz glass sleeve is in the range of 300.0 to 1000.0 μm; the outer diameter of the inner layer of the target quartz glass sleeve is in the range of 90 to 500 μm.

3. The seven-core six-mode fan-in fan-out device according to claim 1, characterized in that: The drilling diameter range of each hole unit of the quincunx-shaped hole in the target quartz glass sleeve is 60.0 to 240.0 μm; the inner diameter major axis range of the quincunx-shaped hole in the target quartz glass sleeve is 180.0 to 720.0 μm; the inner diameter minor axis range of the quincunx-shaped hole in the target quartz glass sleeve is 100.0 to 416.0 μm; the inner diameter peak distance range of the quincunx-shaped hole in the target quartz glass sleeve is 50.0 to 210.0 μm.

4. The seven-core six-mode fan-in fan-out device according to claim 1, characterized in that: The relative refractive index difference between the target quartz glass sleeve and the standard quartz sleeve at a preset wavelength ranges from -0.0030 to -0.0010; wherein the preset wavelength is 1550 nm.

5. The seven-core six-mode fan-in fan-out device according to claim 1, characterized in that: The duty cycle of the target quartz glass sleeve is in the range of 0.40 to 0.

80.

6. The seven-core six-mode fan-in fan-out device according to claim 1, characterized in that: Seven single-core six-mode optical fibers and one seven-core six-mode optical fiber both support LP 01 LP 11a LP 11b LP 21a LP 21b LP 02 Six modes of transmission.

7. A method for preparing a seven-core six-mode fan-in fan-out device, characterized in that: Used to prepare a seven-core six-mode fan-in fan-out device as claimed in any one of claims 1 to 6, comprising: Prepare a target quartz glass sleeve; wherein the target quartz glass sleeve is conical, the outer layer is a common quartz layer, the inner layer is a fluorine-doped quartz layer, and there is a plum blossom-shaped hole in the middle of the inner layer; Each single-core six-mode optical fiber is corroded to obtain each single-core six-mode optical fiber after the corrosion is completed; each single-core six-mode optical fiber after the corrosion is completed is gathered into an optical fiber bundle by a hexagonal arrangement; one end of the optical fiber bundle after the cladding is corroded is inserted into the target quartz glass sleeve along the front end of the taper of the target quartz glass sleeve to obtain the target quartz glass sleeve inserted into the optical fiber bundle; Grind the end face of the target quartz glass sleeve inserted into the optical fiber bundle and the end face of the seven-core six-mode optical fiber to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle and the ground seven-core six-mode optical fiber; connect seven light sources to one end of the optical fiber bundle, and connect an optical power meter to one end of the seven-core six-mode optical fiber; align the central axis corresponding to the tapered rear end face of the ground target quartz glass sleeve inserted into the optical fiber bundle with the central axis corresponding to the ground seven-core six-mode optical fiber, and then rotate until the optical power output by the optical power meter is the maximum, stop rotating, and perform welding at the current alignment position to obtain a completed fan-in fan-out device; The manufactured fan-in fan-out device is packaged in a fiber optic box.

8. The method for preparing a seven-core six-mode fan-in fan-out device according to claim 7, characterized in that: The method for preparing the target quartz glass sleeve comprises: A quincunx-shaped hole capillary preform is prepared, and the quincunx-shaped hole capillary preform is cleaned and put into a drawing tower for drawing to obtain a quincunx-shaped hole fluorine-doped quartz glass sleeve; The fluorine-doped quartz glass sleeve with a plum blossom-shaped hole is tapered to obtain a target quartz glass sleeve; wherein the target quartz glass sleeve is tapered, the outer layer is a common quartz layer, the inner layer is a fluorine-doped quartz layer, and there is a plum blossom-shaped hole in the middle of the inner layer.

9. The method for preparing a seven-core six-mode fan-in fan-out device according to claim 7, characterized in that: The etching of each single-core six-mode optical fiber to obtain each single-core six-mode optical fiber after etching comprises: The coating layer at one end of each single-core six-mode optical fiber is removed, and the optical fiber is cleaned with a dust-free paper towel containing alcohol to obtain each cleaned single-core six-mode optical fiber; Putting each cleaned single-core six-mode optical fiber into a corrosion solution of a first concentration for rapid dissolution and then cleaning to obtain each cleaned single-core six-mode optical fiber; Put each cleaned single-core six-mode optical fiber into a corrosion solution of the second concentration and slowly dissolve it until the centerline inner diameter of each single-core six-mode optical fiber approaches a preset target value, thereby obtaining each single-core six-mode optical fiber after preliminary corrosion; After the initial corrosion, each single-core six-mode optical fiber is again placed in the corrosion solution of the second concentration for dissolution, and taken out once every preset time, and the current diameter of each single-core six-mode optical fiber is measured until each single-core six-mode optical fiber is corroded to the preset diameter, thereby obtaining each single-core six-mode optical fiber after the corrosion is completed; Wherein, the corrosion solution is a hydrofluoric acid solution; the first concentration is 40%; the second concentration is 20%; and the preset time is 5 minutes.

10. The method for preparing a seven-core six-mode fan-in fan-out device according to claim 7, characterized in that: The method of grinding the end face of the target quartz glass sleeve inserted into the optical fiber bundle and the end face of the seven-core six-mode optical fiber to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle and the ground seven-core six-mode optical fiber comprises: The target quartz glass sleeve inserted into the optical fiber bundle is inserted into the ceramic tube, and the ceramic head is ground. After the grinding is completed, the ceramic tube is removed to obtain the ground target quartz glass sleeve inserted into the optical fiber bundle; the seven-core six-mode optical fiber is ground to obtain the ground seven-core six-mode optical fiber.

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