Optical fiber multiplexer and preparation method thereof

Abstract

The invention discloses an optical fiber multiplexer and a preparation method thereof, and relates to optical fiber and optical technologies, and the optical fiber multiplexer comprises an optical fiber bundle mode multiplexing structure which is used for carrying out coupling on multiple paths of double-clad signal optical fibers and realizing mode multiplexing, the cross section of the optical fiber bundle mode multiplexing structure comprises an elliptical cross section structure which is formed by inserting a plurality of paths of double-clad optical fiber bundles subjected to chemical corrosion treatment into a tapering elliptical capillary glass tube and performing fused tapering, and integrated forming and elliptical arrangement of the optical fiber bundles are realized based on the elliptical cross section structure; and the multi-core optical fiber beam shaping output system is fused and coupled with the output end of the optical fiber bundle mode multiplexing structure, a multi-core energy transmission optical fiber is adopted as an output carrier, and the end part of the multi-core energy transmission optical fiber is provided with elliptical micro-nano shaping, so that low-loss output of high-power laser is realized. The single-mode laser output of the high-power fiber laser light source system can be met.

Description

TECHNICAL FIELD

[0001] The application relates to the field of optical fibers and optical technology, and in particular to an optical fiber multiplexer and a preparation method thereof. BACKGROUND

[0002] Patent CN116974018A discloses a multi-core optical fiber multiplexer and a preparation method thereof. The application belongs to the technical field of passive optical devices. A multi-core optical fiber multiplexer and a preparation method thereof are disclosed. A small-diameter optical fiber is fused at one end of a single-mode optical fiber. The cladding diameter of the small-diameter optical fiber is smaller than the cladding diameter of the single-mode optical fiber, and the cladding diameter of the small-diameter optical fiber is equal to the core pitch of the multi-core optical fiber to be matched. The mode field diameter of the small-diameter optical fiber is consistent with the mode field diameter of each core of the multi-core optical fiber. The small-diameter optical fiber is used as a transition optical fiber between the single-mode optical fiber and the multi-core optical fiber to realize high-precision matching of the single-mode optical fiber and the multi-core optical fiber. The problems existing in the prior art preparation method can be avoided. The application has the advantages of good scalability, simple preparation, high precision, and industrialized mass production. However, the design of the patent cannot meet the mode selection and laser coherent synthesis of an ultrahigh-power multi-channel laser source with a power of more than 100,000 watts.

[0003] CN114002777A discloses a multi-core multi-mode optical fiber multiplexer. The multi-core multi-mode optical fiber multiplexer comprises a multi-core multi-mode optical fiber, a multi-core multi-mode optical fiber imaging module, at least two processing mechanisms and an optical processing element. The processing mechanism has a multi-core single-mode optical fiber, a multi-core single-mode optical fiber fan-in / fan-out module, a phase modulation element and a multi-core single-mode optical fiber imaging module. The optical processing element is configured to combine the signal light processed by the at least two processing mechanisms and then enter the multi-core multi-mode optical fiber through the multi-core multi-mode optical fiber imaging module, or is configured to split the signal light processed by the multi-core multi-mode optical fiber imaging module to the at least two processing mechanisms. The light field configuration of the multi-core single-mode optical fiber and each core of the multi-core multi-mode optical fiber is one-to-one corresponding and coincides at the center of the surface of the phase modulation element. The optical fiber multiplexer greatly reduces the number of elements required for multiplexing and improves the integration of the device. The multi-core multi-mode optical fiber multiplexer modularly integrates the mode processing system, but the application of the multiplexer to an ultrahigh-power optical fiber laser source system is extremely complex and has low reliability during long-term use.

[0004] CN114690321A proposes a kind of multi-core few-mode fiber multiplexer based on photon lantern and its manufacturing method, it is a kind of multi-core few-mode fiber multiplexer based on photon lantern and its manufacturing method, including multi-mode fiber photon lantern and multi-core fiber photon lantern, the multi-mode fiber photon lantern includes double-layer glass tube fiber bundle and a multi-mode fiber;The multi-core fiber photon lantern includes: single-layer glass fiber bundle and an output multi-core few-mode fiber are fused at the waist of the single-layer glass tube fiber bundle;Wherein, the output multi-mode fiber of the multi-mode fiber photon lantern is equal to the number of input multi-mode fiber of the multi-core fiber photon lantern, the output multi-mode fiber is fused with the input multi-mode fiber one by one, solve the demand that traditional fiber multiplexer cannot meet multi-core few-mode fiber simultaneously to fiber core multiplexing and mode multiplexing, and the stability of the few-mode multi-core fiber multiplexer of space structure is not easy to guarantee, the problem of large cutting volume is easy to solve integrated package, but the cascade type photon lantern structure formed by the patent, middle adopts multi-mode fiber, multi-mode fiber is relatively thin in high-power laser system transmission process.The middle transition area cannot withstand high-power laser transmission, limits the application of the patent technology in ultra-high power laser light source system and cannot realize the requirement of ultra-high power transmission.

[0005] High-power fiber laser mode conversion technology is the key research direction in the field of high-power continuous laser coherent synthesis application in recent years, high-power fiber optical mode conversion technology mainly applies to ultra-high power fiber laser light source system manufacturing, since it needs to meet the high-power output condition, will face the technical problems such as the mode of output fiber laser is various, the output laser beam quality of fiber laser light source system is poor. SUMMARY

[0006] The embodiment of the present application provides a kind of fiber multiplexer and preparation method thereof, to meet the laser single mode output of high-power fiber laser light source system.

[0007] The embodiment of the present application provides a kind of fiber multiplexer, comprising: Fiber bundle mode multiplexing structure 3 is used for coupling and realizing mode multiplexing to multiple double-clad signal fibers, the cross section of the fiber bundle mode multiplexing structure 3 includes the elliptical cross section structure formed by inserting the multiple double-clad fiber bundle treated by chemical etching into the elliptical capillary glass tube 7 after fusion draw, and the integral molding and elliptical arrangement of the fiber bundle are realized based on the elliptical cross section structure; Multi-core fiber beam shaping output system 4, the output end of the multi-core fiber beam shaping output system 4 is fusedly coupled with the fiber bundle mode multiplexing structure 3, adopts multi-core energy transmission fiber as output carrier, and the end of the multi-core energy transmission fiber has elliptical micro-nano shaping, to realize low-loss output of high-power laser.

[0008] This application provides a method for manufacturing an optical fiber multiplexer, including the following steps: The coatings of N double-clad signal optical fibers are stripped and bundled together using a bundling device. The fiber bundle is inserted into a tapered elliptical capillary quartz tube and then fused and tapered to form an elliptical cross-section, thus forming an elliptical fiber bundle. The tapered region at the output end of the optical fiber bundle is cut to obtain the optical fiber bundle mode multiplexing structure 3; A multi-core power transmission fiber is provided, and an elliptical micro-nano shaping structure is prepared at the end of the multi-core power transmission fiber by two-photon micro-nano printing to form a multi-core fiber beam shaping output system 4. The fiber bundle mode multiplexing structure 3 is fused and coupled with the multi-core fiber beam shaping and output system 4 to obtain a fiber multiplexer.

[0009] This application proposes an innovative new type of fiber optic multiplexer to meet the single-mode output requirements of high-power fiber laser source systems.

[0010] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0011] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic cross-section of the cone waist region of the fiber bundle mode multiplexing structure of the fiber multiplexer in an embodiment of this application; Figure 2 This is a schematic cross-section of the receiver end of the multi-core fiber beam shaping output system of the fiber optic multiplexer according to an embodiment of this application. Figure 3 This is a schematic diagram of the overall structure of the fiber optic multiplexer according to an embodiment of this application. Detailed Implementation

[0012] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0013] In low-power optical communication, the degrees of freedom already developed include amplitude, phase, and polarization state. The previously untapped degree of freedom of mode has become a new focus of attention. Mode is not a new concept; due to limitations in fiber manufacturing processes, the earliest fibers were multimode fibers. From an information theory perspective, each orthogonal mode in a multimode fiber can be considered an independent channel. However, the large number of modes also leads to severe mode dispersion, limiting the performance improvement of fiber coherent combining. Due to the numerous and difficult-to-control modes in traditional multimode fibers, fiber-based mode multiplexing refers to using a finite number of orthogonal modes in the fiber as independent channels for information transmission, thereby significantly increasing the system's transmission capacity. By utilizing different modes in the fiber as new degrees of freedom, the spectral efficiency of the system has been successfully improved. Because fiber modes have relatively large mode field areas, their nonlinear tolerance is also high, thus increasing the capacity of the optical transmission system while avoiding interference from nonlinear effects. Therefore, using a finite number of stable modes in the fiber as independent channels for mode multiplexing can greatly improve system capacity and solve the future bandwidth crisis of single-mode fibers. An fiber multiplexer is a device that couples different modes. Because it involves the multiplexing and demultiplexing of different spatial modes, it is an extremely critical device in fiber mode multiplexing systems. During mode excitation, since single-mode fiber only supports the fundamental mode in the 1-micron band, fundamental mode excitation is the simplest. Since fiber simultaneously supports different higher-order spatial modes, the fundamental mode needs to be converted into higher-order modes; this process is performed by the mode conversion device. The converted higher-order modes, along with the fundamental mode, enter the mode multiplexer for multiplexing.

[0014] Based on this, this application establishes a few-mode fiber transmission system based on a mode multiplexer / demultiplexer. In the embodiments of this application, an fiber multiplexer is provided, such as... Figure 3 As shown, it includes: The fiber bundle mode multiplexing structure 3 is used to couple and multiplex multiple double-clad signal fibers. The cross section of the fiber bundle mode multiplexing structure 3 includes an elliptical cross section structure formed by inserting multiple double-clad fiber bundles that have undergone chemical etching into an elliptical capillary glass tube 7 that has been tapered and then fused and tapered. The elliptical cross section structure is used to realize the integral forming and elliptical arrangement of the fiber bundles.

[0015] like Figure 1 As shown, the fiber bundle photonic mode conversion structure consists of a chemically etched double-clad fiber bundle inserted into a tapered elliptical fluorine-doped capillary quartz tube. The cross-section of the tapered tube after insertion is then melted again, forming an elliptical capillary glass tube. The visible capillary pores of the fiber bundle are slowly extruded to form the fiber bundle optical module into an integral elliptical fiber bundle structure. In some embodiments, the elliptical capillary glass tube 7 is a fluorine-doped elliptical capillary glass tube, or a capillary glass tube with an elliptical inner diameter and a circular outer diameter.

[0016] The fiber bundle cone-waist elliptical structure design in this embodiment breaks through the traditional circular structure design concept (fiber combination: 1, 3, 7…), and innovatively introduces an elliptical structure (fiber combination: 1, 5, 6, 7, 8, 9…). The introduction of the elliptical structure changes the fiber arrangement and improves the duty cycle, which is beneficial for different types of fiber bundle photonic mode conversion structures to adopt an elliptical state. The elliptical arrangement of the fiber bundle is more conducive to vortex laser shaping and transmission.

[0017] In some embodiments, the elliptical cross-section 1 of the fiber bundle mode multiplexing structure 3 is a conical waist section, and the major axis dimension of the elliptical cross-section is more than twice the minor axis dimension. This application is based on the principle that the longitudinal dimension of the elliptical fiber core is twice as long as its transverse dimension, which increases after precise arrangement and fusion coupling. The elliptical structure design is more beneficial for mode multiplexing of multi-channel ultra-high power lasers at the fusion-coupled waist position. Furthermore, the conical region is cut to form a conical demultiplexing, creating an integrated multiplexing / demultiplexing structure. During the transmission of laser modes in multiple fiber channels, while the fiber bundle is multiplexed and demultiplexed, the single-path fiber laser achieves mode selection by adjusting the phase to form a single-mode output. Simultaneously, the integrated elliptical fiber bundle can transmit and withstand ultra-high power lasers.

[0018] A multi-core fiber beam shaping and output system 4 is fusedly coupled to the output end of the fiber bundle mode multiplexing structure 3. The system uses a multi-core power transmission fiber as the output carrier, and the end of the multi-core power transmission fiber has an elliptical micro-nano shaping to achieve low-loss output of high-power laser.

[0019] In a specific example, the fiber bundle mode multiplexing structure 3 can only couple multiple high-power optical fibers into in-phase mode conversion output lasers. When the power of each output laser beam exceeds the kilowatt level, the output end of the fiber bundle mode multiplexing structure 3, located in a conical region, experiences end-face reflection, which can lead to burnout at the output end if not handled properly. In some embodiments, the fiber bundle mode multiplexing structure 3 and the multi-core fiber beam shaping output system 4 are independent modules, horizontally aligned, and then fused and fixed using two-photon micro-nano printing. The multi-core fiber beam end formed by TPP two-photon printing technology in this application forms a micro-nano multi-core elliptical output and receiving structure, reducing optical loss during laser output. Since the ultra-high power fiber laser source system is always operating under ultra-high power laser output conditions, the micro-nano multi-core elliptical structure design formed by TPP two-photon micro-nano printing technology matches the output end of the fiber bundle mode multiplexing structure, improving the beam quality of the output laser. This eliminates the interface between the fiber array and the hollow re-imaging waveguide, avoids surface damage limitations, and achieves selective mode output.

[0020] The fiber optic multiplexer of this application employs a fiber bundle mode multiplexing structure and a multi-core fiber beam shaping output system. Through the fiber bundle mode multiplexing structure, multiple ultra-high power signal laser beams are multiplexed and demultiplexed, while the elliptical structure achieves miniaturization and ensures stable and reliable laser output polarization states. The multi-core fiber beam shaping output system efficiently couples multiple signals, effectively improving the efficiency and reliability of fiber photonic mode conversion coupling output, and providing a new approach for the development of ultra-high power fiber laser systems.

[0021] In some embodiments, the number N of the multiplexed double-clad signal fiber bundles in the fiber bundle mode multiplexing structure 3 is greater than 5, and the following processing is performed to obtain it: Remove the coating from the bundle of N elliptical fiber cores; The fiber optic bundles are arranged and bundled using a suitable bundling device; After the N elliptical fiber bundles are assembled, they are uniformly melted and bonded by multi-directional laser melting, so that the cross section 1 of the deformation zone of the formed fiber bundle mode multiplexing structure 3 is elliptical based on the capillary quartz tube.

[0022] In some embodiments, after the N double-clad signal fiber bundles are fused together, they are cut within a 50-100 micrometer range in the output cone region to connect with the multi-core fiber beam shaping and output system 4.

[0023] In some embodiments, the outer diameter of the multi-core power transmission fiber is no greater than 500 micrometers, the number of fiber cores is greater than 5, and the overall length of the multi-core fiber is greater than 50 centimeters.

[0024] In some embodiments, the receiving end of the multi-core fiber beam shaping and output system 4 has an elliptical cross-section with a major axis of less than 200 micrometers, so as to connect with the output end of the N double-clad signal fiber bundles after fusion molding and cutting, wherein: The receiving end cross-section 2 of the multi-core fiber beam shaping and output system 4 is similar in size to the deformation region cross-section 1 of the fiber bundle mode multiplexing structure 3. The receiver of the multi-core fiber beam shaping and output system 4 has an elliptical cross-section with a major axis of less than 200 micrometers, which is also achieved through two-photon micro-nano printing.

[0025] This application also proposes a method for manufacturing an optical fiber multiplexer, including the following steps: The coatings of N double-clad signal optical fibers are stripped and bundled together using a bundling device. The fiber bundle is inserted into an elliptical capillary quartz tube that has been tapered, and then fused and tapered to form an elliptical cross-section. The tapered region at the output end of the optical fiber bundle is cut to obtain the optical fiber bundle mode multiplexing structure 3; A multi-core power transmission fiber is provided, and an elliptical micro-nano shaping structure is prepared at the end of the multi-core power transmission fiber by two-photon micro-nano printing to form a multi-core fiber beam shaping output system 4. The fiber bundle mode multiplexing structure 3 is fused and coupled with the multi-core fiber beam shaping and output system 4 to obtain a fiber multiplexer.

[0026] The fiber optic multiplexer 6 manufactured in this application, such as... Figure 3 As shown, this application uses an elliptical capillary glass tube 7, and a specially designed bundle-assembly device is used to tightly arrange and output the N double-clad signal fiber bundles at the coupling bundle fusion end. Then, the bundled N elliptical core fiber bundles are uniformly melted and bonded using multi-directional laser melting. The cross-section 1 of the deformation zone of the resulting fiber bundle mode multiplexing structure 3 is shown in the figure. Figure 3 As shown. N double-clad signal fibers are fused together and cut within the 50-100 micrometer range of the output end cone region. After cutting 5, the cut ends are reserved. The cross-section of the fiber bundle photonic mode conversion structure fused coupling region after cutting is shown in Figure 1.

[0027] like Figure 2 As shown, the multi-core fiber beam shaping and output system 4 uses a multi-core power transmission fiber as the coupling and shaping output system. The outer diameter of the multi-core power transmission fiber is ≤500 micrometers, and the number of fiber core channels is greater than 5. The multi-core power transmission fiber can serve as a carrier for single-mode photon output, and the length of the multi-core fiber is designed to be greater than 50 centimeters.

[0028] In a specific example, the application of TPP two-photon technology to micro-nano-shape the cross-section of the multi-core power transmission fiber input end is more conducive to improving the laser beam quality of the multi-photon output and reducing the large insertion loss caused by alignment coupling. In the example of this application, the major diameter of the elliptical cross-section of the multi-core power transmission fiber receiving end is less than 200 micrometers. The cross-section 2 of the resulting multi-core fiber beam shaping output system 4 is similar in size to the cross-section 1 of the deformation region of the fiber bundle mode multiplexing structure 3. After fusion coupling, this helps to improve the overall reliability of the fiber photonic mode converter.

[0029] In this application, the fiber bundle mode multiplexing structure 3 and the multi-core fiber beam shaping and output system 4 can be independent modules. After the two modules are horizontally clamped, fixed, and aligned, they are fused and coupled using TPP two-photon micro-nano technology without any transition measures. They are then horizontally placed and fixed, ultimately forming a novel fiber multiplexer 6.

[0030] This application utilizes a fiber optic bundle mode multiplexing structure to multiplex and demultiplex multiplex ...

[0031] It should be noted that, in the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0032] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0033] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims. All of these forms are within the protection scope of this application.

Claims

1. An optical fiber multiplexer, characterized in that, include: The fiber bundle mode multiplexing structure (3) is used to couple multiple double-clad signal fibers and realize mode multiplexing. The cross section of the fiber bundle mode multiplexing structure (3) includes an elliptical cross section structure formed by inserting multiple double-clad fiber bundles that have been chemically etched into an elliptical capillary glass tube (7) that has been tapered and then fused and tapered. The elliptical cross section structure is used to realize the integral forming and elliptical arrangement of the fiber bundle. A multi-core fiber beam shaping output system (4) is fused to the output end of the fiber bundle mode multiplexing structure (3), uses a multi-core power transmission fiber as the output carrier, and has an elliptical micro-nano shaping at the end of the multi-core power transmission fiber to achieve low-loss output of high-power laser.

2. The optical fiber multiplexer as described in claim 1, characterized in that, The number N of the multi-channel double-clad signal fiber bundles in the fiber bundle mode multiplexing structure (3) is greater than 5, and the following processing is performed to obtain it: Remove the coating from the bundle of N elliptical fiber cores; The fiber optic bundles are arranged and bundled using a suitable bundling device; After the N elliptical fiber bundles are bundled together, they are uniformly melted and bonded by multi-directional laser melting so that the cross section (1) of the deformation zone of the formed fiber bundle mode multiplexing structure (3) is elliptical based on the capillary quartz tube.

3. The optical fiber multiplexer as described in claim 2, characterized in that, After the N double-clad signal fiber bundles are fused together, they are cut in the 50-100 micrometer range of the output cone region to connect with the multi-core fiber beam shaping output system (4).

4. The optical fiber multiplexer as described in claim 3, characterized in that, The elliptical cross section of the fiber bundle mode multiplexing structure (3) is a cone waist region cross section, and the major axis dimension of the elliptical cross section is more than twice the minor axis dimension.

5. The optical fiber multiplexer as described in claim 1, characterized in that, The outer diameter of the multi-core power transmission fiber is no greater than 500 micrometers, the number of fiber cores is greater than 5, and the overall length of the multi-core fiber is greater than 50 centimeters.

6. The optical fiber multiplexer as described in claim 3, characterized in that, The receiving end of the multi-core fiber beam shaping and output system (4) has an elliptical cross-section with a major axis of less than 200 micrometers, so as to connect with the output end of the N double-clad signal fiber bundles after fusion molding and cutting, wherein: The receiving end cross section (2) of the multi-core fiber beam shaping output system (4) is similar in size to the deformation region cross section (1) of the fiber bundle mode multiplexing structure (3). The receiver of the multi-core fiber beam shaping and output system (4) has an elliptical cross-section with a major axis of less than 200 micrometers, which is achieved by two-photon micro-nano printing.

7. The optical fiber multiplexer as described in claim 1, characterized in that, The fiber bundle mode multiplexing structure (3) and the multi-core fiber beam shaping and output system (4) are independent modules, which are horizontally aligned and then fixed by two-photon micro-nano printing fusion coupling.

8. The optical fiber multiplexer as described in claim 1, characterized in that, The elliptical capillary glass tube (7) is a fluorine-doped elliptical capillary glass tube, or a capillary glass tube with an elliptical structure and a circular outer diameter.

9. A method for manufacturing an optical fiber multiplexer, characterized in that, Includes the following steps: The coatings of N double-clad signal optical fibers are stripped and bundled together using a bundling device. The fiber bundle is inserted into a tapered elliptical capillary quartz tube and then fused and tapered to form an elliptical cross-section, thus forming an elliptical fiber bundle. The tapered region at the output end of the elliptical fiber bundle is cut to obtain a fiber bundle mode multiplexing structure (3); A multi-core power transmission fiber is provided, and an elliptical micro-nano shaping structure is prepared at the end of the multi-core power transmission fiber by two-photon micro-nano printing to form a multi-core fiber beam shaping output system (4). The fiber bundle mode multiplexing structure (3) is fused and coupled with the multi-core fiber beam shaping and output system (4) to obtain a fiber multiplexer.

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