Method and device for preparing two-dimensional bound multi-core fiber grating array

Abstract

The invention discloses a two-dimensional bound multi-core fiber grating array preparation method and device, and the method is characterized in that two grating array optical fibers which are customized in grating wavelength and spacing according to needs and are integrally prepared by a drawing tower on line are selected, the two grating array optical fibers are combined into a double-core optical fiber through a beam combining unit, the double-core optical fiber passes through a central hole of a binding unit, and then the two-dimensional bound multi-core fiber grating array is obtained. Any two optical fibers are selected to penetrate through the edge holes of the binding units, and finally the two-dimensional binding multi-core fiber grating array is compounded. According to the two-dimensional binding multi-core fiber grating array preparation method and device, the preparation cost is low, the grating center wavelength consistency, the reflectivity consistency and the grating spectral pattern consistency are good, rolling and twisting cannot occur in the actual arrangement process due to the flat oval physical appearance, and the stability of the array is improved. And the shape sensing precision is high in an actual application scene.

Description

Technical Field

[0001] The present invention relates to the technical field of fiber Bragg grating array manufacturing, and particularly relates to a preparation method and device for a two-dimensional bonded multi-core fiber Bragg grating array. Background Art

[0002] With the development of various fields such as intelligent monitoring, structural safety monitoring, and medical health monitoring, fiber Bragg gratings and special optical fibers play important roles in them. As a new type of optical sensing element, an optical fiber has the advantages of small size, resistance to harsh environments, anti-electromagnetic interference, corrosion resistance, high sensitivity and accuracy, and good implantability. The optical fiber shape sensing technology can be used for structural monitoring in fields such as aerospace, industrial machinery, and large buildings, geographical environment and cable pipeline monitoring, and in the medical field, it can be used for interventional treatment tracking, minimally invasive medical interventional surgery, intelligent health monitoring, etc. In industry, it can realize the production and manufacturing of industrial robots, showing great application potential with its unique advantages.

[0003] A multi-core optical fiber is a special optical fiber that accommodates multiple cores. It contains multiple cores within the same outer cladding and is often used in the field of shape sensing. Currently, the existing centimeter-level multi-core optical fibers have been applied in various fields such as medical endoscopes, minimally invasive surgeries, wearable devices, and industrial robots. A multi-core fiber Bragg grating array made by writing fiber Bragg gratings in a multi-core optical fiber can more accurately achieve multi-parameter sensing and monitoring of stress and strain, temperature, and shape. However, whether it is a multi-core optical fiber or a multi-core fiber Bragg grating array, its physical structure appears cylindrical in appearance. When laying a multi-core optical fiber in practical applications, it is impossible to avoid or monitor the rolling and twisting of the multi-core optical fiber. The existence of rolling and twisting will cause wavelength data deviation of the multi-core fiber Bragg grating array, complex calibration, and a decrease in shape reconstruction accuracy.

[0004] Currently, the preparation technologies for multi-core fiber Bragg grating arrays mainly include methods such as shaft engraving, removing the coating layer for single-point engraving, and discontinuous engraving. It is difficult to ensure the consistency of fiber Bragg gratings, and the preparation time is long, the cost is high, and it does not have the conditions for mass production.

[0005] In view of the various deficiencies in the above-mentioned multi-core fiber grating preparation method, firstly, the current preparation technology is complex, the grating consistency is poor, the time is long, and the cost is high; secondly, the physical structure of the multi-core fiber presents a cylindrical shape in appearance, and it is impossible to avoid or monitor the rolling and torsion of the multi-core fiber during actual laying, which will lead to the deviation of the wavelength data of the multi-core fiber grating array, complex calibration, and the decline of the shape reconstruction accuracy. The present invention proposes a preparation method and device for a two-dimensional bound multi-core fiber grating array, in which two grating array fibers are bound in parallel and then compounded into a single dual-core fiber, and then two fibers are arranged on both sides of the dual-core fiber, and finally a two-dimensional bound multi-core fiber grating array is formed. Its physical shape is a flat ellipse, and the fiber grating array is integrally prepared online by a fiber drawing tower. The grating wavelength, reflectivity, physical grating spacing, etc. can be customized with high consistency, the physical strength of the fiber is high, the preparation process is simple, and industrial production can be realized.

[0006] The present invention proposes a preparation method and device for a two-dimensional bound multi-core fiber grating array. The preparation method is based on the grating array fiber integrally prepared online by a fiber drawing tower. Two grating array fibers with customized grating wavelength and spacing are selected, and they are compounded into a single dual-core fiber through a beam combining unit. The dual-core fiber is passed through the central hole of the binding unit, and then any two fibers are passed through the edge holes of the binding unit, and finally a two-dimensional bound multi-core fiber grating array is compounded. The preparation cost of a two-dimensional bound multi-core fiber grating array prepared according to the method is low, the fiber gratings integrally prepared online by the fiber drawing tower have good consistency, the flat elliptical physical appearance will not roll and twist during actual laying, and the sensing accuracy for the shape is high in actual application scenarios. Summary of the Invention

[0007] The present invention provides a preparation method and device for a two-dimensional bound multi-core fiber grating array, which solves the problems of high preparation cost of general multi-core fiber gratings and the inability to avoid rolling and torsion during laying. The preparation steps are clear, the preparation device is simple, the production cost is low, industrial production can be realized, and the sensing accuracy for the shape in actual application scenarios is high, with great potential and obvious advantages.

[0008] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0009] A preparation device for a two-dimensional bound multi-core fiber grating array includes a set of fiber feeding units (1), two grating array fibers (2), two ordinary single-mode fibers (3), a beam combining unit (4), a No. 1 coating cup (5), a No. 1 ultraviolet curing lamp (6), a binding unit (7), a No. 2 coating cup (8), a No. 2 ultraviolet curing lamp (9), and a fiber winding device (10). The above-mentioned devices and components are arranged in sequence in the vertical direction.

[0010] The fiber feeding unit (1) is a rectangular device, including four rollers that can rotate in any direction and are used to place the optical fibers to be bonded. During actual bonding, its rotation direction is set so that the optical fibers to be bonded are fed downward in the required direction.

[0011] The two fiber grating array optical fibers (2) are integrally prepared online in a fiber drawing tower. The fiber grating array is inscribed during the fiber drawing process, and it can customize the wavelength, reflectivity, and physical pitch of the fiber grating, with high consistency and high tensile strength of the optical fiber.

[0012] The two ordinary single-mode optical fibers (3) are drawn from a preform rod. There is no need for grating inscription, the drawing speed is fast, and the preparation cost is low.

[0013] The beam combining unit (4) is an elliptical device formed by two tangent circular holes. Each hole can pass through one fiber grating array optical fiber and is used for beam combining of the two fiber grating array optical fibers. After beam combining, the two fiber grating array optical fibers are arranged vertically and horizontally to form an elliptical dual-core fiber grating array.

[0014] The No. 1 coating cup (5) has a bowl-shaped structure and is used in combination with the No. 1 ultraviolet curing lamp (6) for coating the dual-core optical fiber to protect the optical fiber structure.

[0015] The bonding unit (7) has an annular structure, including a central hole and two edge holes. The size of the central hole is the same as that of the beam combining unit and is used to limit the dual-core fiber grating array to pass through it. There is one edge hole on each side of the central hole, which is a circular hole and is used to limit the two ordinary single-mode optical fibers to pass through it. The dual-core fiber grating array and the two ordinary single-mode optical fibers are combined through the bonding unit to form a two-dimensionally bonded multi-core fiber grating array.

[0016] The No. 2 coating cup (8) has a bowl-shaped structure and is used in combination with the No. 2 ultraviolet curing lamp (9) for coating the two-dimensionally bonded multi-core fiber grating array to protect the optical fiber structure.

[0017] The fiber winding device (10) consists of two rollers with different sizes. The two-dimensionally bonded multi-core fiber grating array prepared by the above device is wound into a coil after passing through the two rollers with different sizes.

[0018] The specific steps are as follows:

[0019] Step 1: Prepare a dual-core fiber grating array: Feed the two fiber grating array optical fibers evenly and at a constant speed through the fiber feeding unit to the beam combining unit. The beam combining unit is an elliptical device formed by two tangent circular holes. The two fiber grating array optical fibers pass through the two circular holes respectively. After beam combining, they enter the No. 1 coating cup, and after coating, they are cured by the No. 1 ultraviolet curing lamp to form a dual-core optical fiber for subsequent use.

[0020] Step 2: Prepare a two-dimensional bonded multi-core fiber grating array: Feed two ordinary single-mode fibers into the bonding unit at a uniform speed through the fiber feeding unit. The bonding unit includes three holes. The size of the central hole is the same as that of the beam combining unit and is used to pass through the dual-core fiber grating array. There is a circular hole on each side of the central hole, namely the edge hole, which is used to pass through the two ordinary single-mode fibers. The dual-core fiber grating array and the two ordinary single-mode fibers are combined into a two-dimensional bonded multi-core fiber grating array through the bonding unit, coated with glue and fixed by the No. 2 coating cup and the No. 2 ultraviolet curing lamp, and finally wound into a coil by the fiber winding unit.

[0021] The physical structure of the two-dimensional bonded multi-core fiber grating array is a multi-core fiber grating array with a 4-core structure formed by binding a dual-core fiber grating array and two ordinary single-mode fibers. The two cores of the dual-core fiber grating array are arranged longitudinally, and the two ordinary single-mode fibers are arranged transversely on both sides of the dual-core fiber grating array; the dual-core fiber grating array is formed by combining two grating array fibers prepared online by two fiber drawing towers, and the fiber grating wavelength, reflectivity and grating physical pitch can be customized. The two ordinary single-mode fibers play a supporting role; the overall physical structure presents an oblate ellipse in appearance, and the laying direction can be accurately controlled to prevent the fiber from twisting or rolling.

[0022] The beneficial effects of the present invention are as follows:

[0023] (1) The present invention proposes a preparation method for a two-dimensional bonded multi-core fiber grating array. The present invention selects grating array fibers prepared by a fiber drawing tower, completes fixed-point grating engraving during the process of preparing the fiber by the fiber drawing tower, realizes flexible configuration of the number and pitch of gratings, and has high consistency of grating wavelength and reflectivity. Select two grating array fibers prepared by the above method, and form a dual-core fiber grating array after beam combination. The method for preparing the multi-core fiber grating array replaces the method for preparing the multi-core fiber grating array by engraving gratings on existing multi-core fibers, without the need for point-by-point core positioning engraving, without complex fiber fan-in and fan-out devices, etc., greatly reducing the preparation cost of the multi-core fiber grating array, ensuring the grating consistency and engraving efficiency while meeting the needs of low-cost industrial production and meeting the industrial preparation conditions.

[0024] (2) The present invention binds and composites a dual-core fiber grating array and two ordinary single-mode fibers into a two-dimensional bonded multi-core fiber grating array. The preparation device is simple and the process is easy to understand. Moreover, according to different application requirements, a determined core pitch and the grating pitch in the core can be selected, and the application is flexible.

[0025] (3) A two-dimensional bonded multi-core fiber grating array prepared by the present invention has an oblate ellipse appearance in its physical structure. When laying multi-core fibers in practical applications, the rolling and twisting of multi-core fibers can be avoided, and there will be no automatic offset or chirping of the grating wavelength. The shape sensing accuracy is high and the shape reconstruction effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the overall device structure of the present invention.

[0027] Figure 2 This is a schematic diagram of a two-dimensional bonded multi-core fiber grating array of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described below with reference to the accompanying drawings.

[0029] Referring to Figure 1 , the present invention discloses a two-dimensional bonded multi-core fiber grating array and a preparation method thereof, including a fiber feeding unit (1), two grating array optical fibers (2), two ordinary single-mode optical fibers (3), a beam combining unit (4), a first coating cup (5), a first ultraviolet curing lamp (6), a bonding unit (7), a second coating cup (8), a second ultraviolet curing lamp (9), and a fiber winding device (10); wherein the fiber feeding unit (1) uniformly and steadily feeds out two grating array optical fibers (2) and two ordinary single-mode optical fibers (3) as a fiber feeding device, the beam combining unit (4) completes the preparation of the dual-core fiber grating array, and the bonding unit composites the dual-core fiber grating array and two ordinary single-mode optical fibers to form a two-dimensional bonded multi-core fiber grating array. The fiber feeding unit (1), the beam combining unit (4), the first coating cup (5), the first ultraviolet curing lamp (6), the bonding unit (7), the second coating cup (8), the second ultraviolet curing lamp (9), and the fiber winding unit (10) are arranged in sequence in the vertical direction.

[0030] Referring to Figure 2 , this is a schematic diagram of a two-dimensional bonded multi-core fiber grating array related to the present invention, which is composed of four optical fibers. The two longitudinally arranged in the middle are grating array optical fibers, which are combined to form a dual-core fiber grating array, and one ordinary single-mode optical fiber is arranged on each side of it, and the whole is arranged horizontally; wherein the dual-core fiber grating array is formed by combining two grating array optical fibers prepared integrally online by two fiber drawing towers, and the wavelength, reflectivity and physical pitch of the fiber grating can be customized, and the two ordinary single-mode optical fibers play a supporting role; the overall physical structure is a flat oval appearance that can avoid the torsion and rolling of the optical fiber.

[0031] The working mode of the present invention is as follows: The fiber feeding unit (1) feeds out two fiber grating array optical fibers (2) and two ordinary single-mode optical fibers (3). After the two fiber grating array optical fibers (2) are fed out uniformly at a constant speed, they reach the beam combining unit (4). The beam combining unit is an elliptical device formed by two tangent circular holes. The two fiber grating array optical fibers (2) pass through the two circular holes respectively, and after beam combining, they enter the No. 1 coating cup (5). After coating, they are cured by the No. 1 ultraviolet curing lamp (6) to form a double-core fiber grating array. The two ordinary single-mode optical fibers (3) are fed to the binding unit (7) uniformly at a constant speed through the fiber feeding unit (1). The binding unit (7) includes three holes. The size of the central hole is the same as that of the beam combining unit, and there is a circular hole on each side of the central hole, that is, the edge hole. The double-core fiber grating array passes through the central hole into the No. 2 coating cup (8), and the two ordinary single-mode optical fibers (3) pass through the edge holes into the No. 2 coating cup (8), and are combined into a two-dimensional bound multi-core fiber grating array (11), which is cured by the No. 2 ultraviolet curing lamp (9) to form a shape, and finally is wound into a coil by the fiber receiving unit (10).

[0032] A method for preparing a two-dimensional bound multi-core fiber grating array according to the present invention selects a fiber grating array optical fiber prepared by a fiber drawing tower, and completes fixed-point grating writing during the process of preparing the optical fiber by the fiber drawing tower. The method for preparing the multi-core fiber grating array is used to replace the method for preparing the multi-core fiber grating array by grating writing on the existing multi-core optical fiber. There is no need for point-by-point core positioning grating writing, avoiding the loss caused by the coupling between the single-mode optical fiber and the multi-core optical fiber, greatly reducing the preparation cost of the multi-core fiber grating array, ensuring the grating consistency and writing efficiency, and realizing the low-cost industrial production requirements while meeting the industrial preparation conditions.

[0033] A two-dimensional bound multi-core fiber grating array according to the present invention has a physical structure that appears flat and elliptical in appearance. When laying the multi-core optical fiber in practical applications, it can avoid the rolling and torsion of the multi-core optical fiber, and there will be no automatic shift or chirping of the grating wavelength. It has high shape sensing accuracy and good shape reconstruction effect, and is flexible and widely applicable.

[0034] The key technologies for the device to realize the preparation of the two-dimensional bound multi-core fiber grating array are as follows:

[0035] 1. When placing the fiber grating array optical fiber on the four rollers of the fiber feeding unit, the fiber grating array optical fiber is placed on the middle two rollers, and the ordinary single-mode optical fiber is placed on the rollers on both sides. When the fiber feeding unit starts to feed the fiber, first start the two middle rollers, so that the two middle rollers feed the fiber at the same speed and at a constant speed. After forming a double-core optical fiber through the beam combining unit, then start the rollers on both sides to feed the fiber, and the fiber feeding speed is controlled at 5-10 m / min.

[0036] 2. The diameters of the two circular tangent holes of the beam combining unit should be the same as the coating diameter of the selected fiber grating array fiber, so as to limit and fix the positions of the two fiber grating array fibers and avoid the fibers from winding around each other during the beam combining process. The diameter of the central hole of the binding unit should be the same as the diameter of the dual-core fiber formed by beam combining, and the diameters of the two edge holes should be the same as the coating diameter of the selected ordinary single-mode fiber, which plays a role in limiting and fixing the fiber positions.

[0037] 3. When customizing the grating wavelength, reflectivity and grating physical pitch of the fiber grating array fiber, it is necessary to calibrate the grating position to ensure that each group of gratings is at the same horizontal position during beam combining.

[0038] In a specific embodiment of the present invention, the 4 fibers sent out by the fiber feeding unit at a speed of 20 m / min are conventional ordinary single-mode fibers (G625), with a core diameter of 8.2 μm and a cladding diameter of 125 μm. Among them, two fibers are engraved with gratings and are fiber grating array fibers. The central wavelengths of the fiber gratings are 1530 nm and 1548 nm, the bandwidth is 0.15 nm, the reflectivity is 0.1%, and the physical interval between the fiber gratings is 2 m. The dual-core fiber grating array formed by beam combining of the two fiber grating array fibers is elliptical, with the cores tangent to each other, the major axis is 325 μm, and the minor axis is 200 μm. The dual-core fiber grating array and the two ordinary single-mode fibers are bound by the binding unit to form a two-dimensional bound multi-core fiber grating array. The two ordinary single-mode fibers are symmetrically arranged on both sides of the dual-core fiber grating array, and the distance between their cores and the center point of the dual-core fiber grating array is 140 μm. The schematic diagram of the two-dimensional bound multi-core fiber grating array is shown in Figure 2 , the physical shape of the fiber is a flat ellipse, with the major axis of 600 μm, the minor axis of 325 μm, and the total length of 1 km. The preparation method of the two-dimensional bound multi-core fiber grating array proposed by the present invention can effectively realize long-distance industrial production at the meter level or even the kilometer level, with low cost and simple system; its flat elliptical physical appearance makes the shape sensing accuracy and reconstruction effect better in practical applications.

[0039] The above shows and describes the basic principles and main features of the present invention. The fiber sizes and parameters mentioned in the invention are an example of the present invention. The present invention also has various other examples not mentioned. Without departing from the spirit and scope of the present invention, various changes and improvements of the present invention fall within the scope of the present invention claimed.

Claims

1. A preparation device for a two-dimensional bonded multi-core fiber grating array, characterized in that, It includes a fiber feeding unit, a fiber grating array optical fiber, a common single-mode optical fiber, a beam combining unit, a No. 1 coating cup, a No. 1 ultraviolet curing lamp, a binding unit, a No. 2 coating cup, a No. 2 ultraviolet curing lamp and a fiber receiving unit; the above units and devices are arranged in sequence in the vertical direction; The fiber feeding unit is a rectangular device, including four rollers that can rotate in any direction, used to place the optical fiber to be bound. During actual binding, set its rotation direction so that the optical fiber to be bound is fed downward in the required direction; The fiber grating array optical fiber is prepared online integrally with a drawing tower, and the inscription of the fiber grating array with specific fiber grating reflection wavelength, reflectivity and grating physical pitch is completed during the drawing process; The two common single-mode optical fibers are directly drawn from a preform rod; The beam combining unit is an elliptical device formed by two tangent circular holes. Each hole can pass through a fiber grating array optical fiber and is used for the beam combining of two fiber grating array optical fibers. After beam combining, a dual-core optical fiber is formed; The No. 1 coating cup is a bowl-shaped structure, used in combination with the No. 1 ultraviolet curing lamp for the coating work of the dual-core optical fiber to protect the optical fiber structure; The binding unit is a circular ring structure, including a central hole and two edge holes. The size of the central hole is the same as that of the beam combining unit, used to limit the dual-core fiber grating array so that it passes through; there is one edge hole on each side of the central hole, which is a circular hole, used to limit the two common single-mode optical fibers so that they pass through; the dual-core fiber grating array and the two common single-mode optical fibers are combined through the binding unit to form a two-dimensionally bound multi-core fiber grating array; The No. 2 coating cup is a bowl-shaped structure, used in combination with the No. 2 ultraviolet curing lamp for the coating work of the two-dimensionally bound multi-core fiber grating array to protect the optical fiber structure; The fiber receiving device consists of two rollers of different sizes. The two-dimensionally bound multi-core fiber grating array prepared by the above device is wound into a coil after passing through the two rollers of different sizes.

2. A method for preparing a two-dimensionally bound multi-core fiber grating array, the specific steps include: Step 1: Prepare a dual-core fiber grating array: Feed two fiber grating array optical fibers evenly and at a constant speed through the fiber feeding unit to the beam combining unit. The beam combining unit is an elliptical device formed by two tangent circular holes. The two fiber grating array optical fibers pass through the two circular holes respectively. After beam combining, they enter the No. 1 coating cup, and after coating, they are cured and formed by the No. 1 ultraviolet curing lamp to prepare a dual-core optical fiber for subsequent use; Step 2: Prepare a two-dimensionally bound multi-core fiber grating array: Feed two common single-mode optical fibers evenly and at a constant speed through the fiber feeding unit to the binding unit. The binding unit includes a central hole and two edge holes; the size of the central hole is the same as that of the beam combining unit, used to limit the dual-core fiber grating array so that it passes through; there is one edge hole on each side of the central hole, which is a circular hole, used to limit the two common single-mode optical fibers so that they pass through; the dual-core fiber grating array and the two common single-mode optical fibers are combined through the binding unit to form a two-dimensionally bound multi-core fiber grating array, which is coated and fixed by the No. 2 coating cup and the No. 2 ultraviolet curing lamp, and finally wound into a coil through the fiber receiving unit.

3. A two-dimensional bound multi-core fiber grating array, characterized in that, A multi-core fiber grating array with a 4-core structure is formed by bundling a dual-core fiber grating array and two ordinary single-mode fibers. The dual-core fiber grating array is formed by combining two fiber grating arrays. The fiber grating array is prepared online integrally in a fiber drawing tower, and the inscription of the fiber grating array with specific fiber grating reflection wavelength, reflectivity, and grating physical pitch is completed during the fiber drawing process. The two cores of the dual-core fiber grating array are arranged longitudinally, and the two ordinary single-mode fibers are arranged transversely on both sides of the dual-core fiber grating array to play a supporting role. The overall physical structure of the two-dimensional bound multi-core fiber grating array has a flat oval appearance that can avoid fiber torsion and rolling.

Images