A method, apparatus, medium, and product for measuring a chiral coupling fiber helical period
By obtaining the refractive index distribution and loss peak wavelength of chiral coupled optical fibers and combining them with finite element method calculations, the problems of inaccurate and time-consuming measurement of the helical period of chiral coupled optical fibers in the prior art have been solved, and rapid and accurate measurement results have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUAZHONG UNIV OF SCI & TECH
- Filing Date
- 2026-06-02
- Publication Date
- 2026-07-24
AI Technical Summary
Existing technologies make it difficult to quickly and accurately measure the helical period of chiral coupled optical fibers. Microscopic measurements are particularly prone to errors under background light conditions, and fiber polishing is time-consuming and inaccurate.
By obtaining the refractive index distribution of the chiral coupled fiber, the core diameter and spacing of the main core and side cores are determined. The refractive index variation curve is calculated using the finite element method, and the spiral period is measured by combining the loss peak wavelength. Spectral data are obtained using the near-field refraction method and a spectrometer.
This method enables rapid and accurate measurement of the helical period of chiral coupled optical fibers, avoiding errors from microscopic observation and the time-consuming nature of fiber polishing, thus improving testing efficiency.
Smart Images
Figure CN122448481A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of special optical fibers, and in particular to a method, device, medium and product for measuring the helical period of chiral coupled optical fibers. Background Technology
[0002] Chiral coupled fiber is a special type of fiber capable of single-mode operation with a large mode field. The helical period is a crucial parameter of chiral coupled fiber. Due to its small helical period, side images are prone to overlap, significantly increasing the difficulty of identification. It is impossible to measure the helical period from the side of the chiral coupled fiber using a microscope in the presence of background light. One method involves observing the initial azimuth angle of the side core relative to the main core in the cross-section of the chiral coupled fiber under a microscope. The fiber is then fixed, and a specific length is cut along the fiber axis. The azimuth angle of the side core relative to the main core is observed again. The helical period of the chiral coupled fiber can be calculated by dividing the change in azimuth angle between the two observations by the length of the cut fiber. However, in cases where the helical period cannot be predicted, the cut fiber may contain multiple helical periods, making accurate calculation of the helical period impossible. Alternatively, the chiral coupled fiber can be fixed in a curable adhesive, the initial azimuth angle of the side core relative to the main core can be recorded, the fiber can be polished along the axial direction while the polishing distance and the azimuth angle of the side core relative to the main core are measured, and the helical period of the chiral coupled fiber can be calculated by dividing the change in the two azimuth angles by the length of the polished fiber. However, polishing the fiber usually takes a long time and cannot quickly obtain the helical period of the fiber. Summary of the Invention
[0003] The purpose of this application is to provide a method, device, medium, and product for measuring the helical period of chiral coupled optical fibers, which can quickly and accurately measure the helical period of chiral coupled optical fibers.
[0004] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a method for measuring the helical period of a chiral coupled optical fiber, comprising: Obtain the refractive index distribution of chiral coupled optical fibers; The core diameter, side core diameter, and spacing between the core and side core of the chiral coupled fiber are determined based on the refractive index distribution of the chiral coupled fiber. The refractive index variation curves of the main core and the straight waveguide side core are determined based on the refractive index distribution of the chiral coupled optical fiber. Obtain the wavelength corresponding to the loss peak; The helical period of the chiral coupled fiber is determined based on the core diameter of the main core, the core diameter of the side core, the spacing between the main core and the side core, the wavelength corresponding to the loss peak, the refractive index variation curve of the main core, and the refractive index variation curve of the straight waveguide side core.
[0005] In one embodiment, the process of obtaining the refractive index distribution of a chiral coupled optical fiber includes: The refractive index distribution of chiral coupled optical fibers was measured using the near-field refraction method.
[0006] In one embodiment, the refractive index distribution of a chiral coupled optical fiber is measured using the near-field refraction method, including: Polishing is performed on the hand-coupled optical fiber; The end face of the polished chiral coupled fiber was immersed in a matching liquid with a set refractive index to obtain the near-field light intensity distribution of the chiral coupled fiber. The refractive index distribution of chiral coupled optical fibers is obtained based on the quantitative relationship between light intensity distribution and refractive index in near-field optics.
[0007] In one embodiment, determining the refractive index variation curve of the core and the refractive index variation curve of the straight waveguide side core based on the refractive index distribution of the chiral coupled optical fiber includes: The refractive index variation curves of the main core and the straight waveguide side core are determined using the finite element method based on the refractive index distribution of the chiral coupled optical fiber.
[0008] In one embodiment, determining the helical period of the chiral coupled fiber based on the main core diameter, the side core diameter, the spacing between the main core and the side core, the wavelength corresponding to the loss peak, the refractive index variation curve of the main core, and the refractive index variation curve of the straight waveguide side core includes: The distance between the center point of the main core and the center point of the side core is determined based on the main core diameter, the side core diameter, and the distance between the main core and the side core. The first refractive index is determined based on the wavelength corresponding to the loss peak and the refractive index variation curve of the main core. The second refractive index is determined based on the wavelength corresponding to the loss peak and the refractive index variation curve of the straight waveguide core. The helical period of the chiral coupled optical fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index.
[0009] In one implementation, a formula is used. The helical period of the chiral coupled optical fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index. In the formula, This indicates the helical period of a chiral coupled fiber. This indicates the distance between the center point of the main core and the center point of the side core. Indicates the first refractive index. This indicates the second refractive index.
[0010] In one embodiment, the process of obtaining the wavelength corresponding to the loss peak includes: Couple a broadband light source into a chiral coupled optical fiber; Obtain the output spectrum of the chiral coupled fiber; The wavelength corresponding to the loss peak is determined based on the output spectrum.
[0011] In a second aspect, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the chiral coupled fiber spiral period measurement method described above.
[0012] Thirdly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the chiral coupled fiber spiral period measurement method described above.
[0013] Fourthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the chiral coupled fiber spiral period measurement method described above.
[0014] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method, device, medium, and product for measuring the helical period of chiral coupled optical fibers. First, the refractive index distribution of the chiral coupled fiber is obtained. Then, the core diameter of the main core, the core diameter of the side core, and the spacing between the main core and the side core are determined. The refractive index variation curves of the main core and the straight waveguide side core are also determined. Furthermore, the wavelength corresponding to the loss peak is obtained. Finally, based on the core diameter of the main core, the core diameter of the side core, the spacing between the main core and the side core, the wavelength corresponding to the loss peak, the refractive index variation curves of the main core and the straight waveguide side core, the helical period of the chiral coupled fiber is determined. This method not only avoids the inaccuracy in measuring the helical period of chiral coupled optical fibers caused by microscopic observation but also avoids the time-consuming problem caused by fiber polishing, thus improving the testing efficiency of the helical period of chiral coupled optical fibers and enabling rapid and accurate measurement and determination of the helical period. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a flowchart of a chiral coupled optical fiber spiral period measurement method according to an embodiment of this application; Figure 2A schematic diagram of the refractive index distribution curve of a chiral coupled optical fiber provided in an embodiment of this application; Figure 3 A schematic diagram of the refractive index variation curve of the main core and the refractive index variation curve of the straight waveguide side core provided in an embodiment of this application; Figure 4 This is a schematic diagram of a straight waveguide side core structure provided in an embodiment of this application; Figure 5 A schematic diagram of the helical period of a chiral coupled optical fiber provided in an embodiment of this application; Figure 6 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.
[0017] Figure labels: 1-Main core diameter, 2-Side core diameter, 3-Spacing between main core and side core, 4-Refractive index variation curve of main core, 5-Refractive index variation curve of straight waveguide side core, 6-Wavelength corresponding to loss peak, 7-Helical period, 8-Refractive index variation curve of helical structure modified side core. Detailed Implementation
[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] In one exemplary embodiment, such as Figure 1 As shown, a method for measuring the spiral period of a chiral coupled optical fiber is provided, including: Step S1: Obtain the refractive index distribution of the chiral coupled fiber.
[0021] Step S2: Determine the core diameter 1, side core diameter 2, and spacing 3 between the core and side core of the chiral coupled fiber based on the refractive index distribution of the fiber.
[0022] Step S3: Determine the refractive index variation curve 4 of the main core and the refractive index variation curve 5 of the straight waveguide side core based on the refractive index distribution of the chiral coupled fiber.
[0023] Step S4: Obtain the wavelength 6 corresponding to the loss peak.
[0024] Step S5: Determine the helical period 7 of the chiral coupled fiber based on the main core diameter 1, the side core diameter 2, the spacing between the main core and the side core 3, the wavelength corresponding to the loss peak 6, the main core refractive index change curve 4, and the straight waveguide side core refractive index change curve 5.
[0025] In one embodiment, the implementation process of step S1 may include: measuring the refractive index distribution of a chiral coupled fiber using a near-field refraction method. Specifically, the process of measuring the refractive index distribution of a chiral coupled fiber using a near-field refraction method includes: polishing the chiral coupled fiber; immersing the end face of the polished chiral coupled fiber in a matching liquid with a set refractive index to obtain the near-field light intensity distribution of the chiral coupled fiber; and obtaining the refractive index distribution of the chiral coupled fiber based on the quantitative relationship between light intensity distribution and refractive index in near-field optics.
[0026] The matching fluid with a set refractive index can be configured according to actual needs. After immersing the polished end face of the chiral coupled fiber into the matching fluid with the set refractive index, the near-field light intensity distribution formed by the different refractive effects of light in different refractive index regions, combined with the quantitative relationship that the light intensity distribution is proportional to the square of the refractive index in near-field optics, can be used to deduce the refractive index distribution inside the chiral coupled fiber (core, side core, and cladding). Based on the refractive index distribution curve of the chiral coupled fiber, the core diameter 1, side core diameter 2, and the spacing 3 between the core and side cores are determined. The core diameter is usually defined as the lateral distance on the refractive index distribution curve from the center to a certain proportion (such as half of the maximum value or the intersection with the cladding refractive index). The core diameter 1, side core diameter 2, and the spacing 3 between the core and side cores can be calculated using the correspondence between the coordinates on the two-dimensional curve and the actual physical dimensions. The refractive index distribution curve inside the chiral coupled fiber, as well as the core diameter 1, side core diameter 2, and the spacing 3 between the core and side cores, are shown below. Figure 2 As shown. In this embodiment, the main core diameter is 35 μm, the side core diameter is 12 μm, the cladding diameter is 250 μm, and the spacing between the main core and the side core is 3 μm.
[0027] In one embodiment, step S3 includes: using the finite element method to determine the refractive index variation curve 4 of the main core and the refractive index variation curve 5 of the straight waveguide side core based on the refractive index distribution of the chiral coupled fiber. The refractive index variation curve 4 of the main core and the refractive index variation curve 5 of the straight waveguide side core are as follows... Figure 3 As shown.
[0028] For example, for a given wavelength, the finite element method is used to obtain the modes (including the core mode and the straight waveguide side-core mode) and refractive index of the chiral coupled fiber corresponding to that wavelength based on the geometry of the cross-section and the refractive index distribution of the chiral coupled fiber. By calculating multiple wavelengths, the refractive index variation relationship of the core mode with wavelength (i.e., core refractive index variation curve 4) and the refractive index variation relationship of the straight waveguide side-core mode with wavelength (i.e., straight waveguide side-core refractive index variation curve 5) can be obtained. Here, the straight waveguide side-core is the waveguide when the side-core is parallel to the core. The straight waveguide side-core structure is as follows: Figure 4 As shown, the core mode and side-core mode can achieve quasi-phase matching with the assistance of orbital angular momentum, leading to energy coupling between modes. Due to the inherently high-loss characteristics of the helical structure of chiral coupled fibers, a loss peak appears in the core mode, which achieves quasi-phase matching with the side-core mode.
[0029] Step S4 includes: coupling a broadband light source into a chiral coupled fiber; acquiring the output spectrum of the chiral coupled fiber (by measuring the output spectrum after transmission using a spectrometer); and determining the wavelength 6 corresponding to the loss peak based on the output spectrum.
[0030] In one embodiment, the implementation process of step S5 includes: S51, the distance between the center point of the main core and the center point of the side core is determined based on the main core diameter 1, the side core diameter 2 and the distance between the main core and the side core 3.
[0031] S52, the first refractive index is determined based on the wavelength 6 corresponding to the loss peak and the refractive index change curve 4 of the main core.
[0032] S53, the second refractive index is determined based on the wavelength 6 corresponding to the loss peak and the refractive index change curve 5 of the straight waveguide side core.
[0033] S54, the helical period of the chiral coupled fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index. Specifically, the formula is used. The helical period of the chiral coupled fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index. Where, This indicates the helical period of a chiral coupled fiber. This indicates the distance between the center point of the main core and the center point of the side core. Indicates the first refractive index. This indicates the second refractive index.
[0034] Among them, a loss peak exists near the intersection of the refractive index variation curve 4 of the main core and the refractive index variation curve 5 of the straight waveguide side core. However, the wavelength of the loss peak deviates from the wavelength of the intersection point. This deviation is caused by the effective refractive index of the helical structure-modified side core. The refractive index of the helical structure-modified side core is the refractive index of the straight waveguide side core multiplied by a coefficient. Therefore, the wavelength at the intersection of curve 8 (refractive index change of the modified core) and curve 4 (refractive index change of the main core) is the wavelength 6 corresponding to the loss peak. Figure 3 As shown. The spiral period 7 can be calculated by finding the refractive index (i.e., the first refractive index) corresponding to the main core mode and the refractive index (i.e., the second refractive index) corresponding to the straight waveguide side core mode from the wavelength of the loss peak. Figure 5 As shown.
[0035] In conjunction with the above embodiments, this application provides a method for measuring the helical period of a chiral coupled optical fiber. The chiral coupled optical fiber includes a core, side cores rotating around the core at a fixed period, and a cladding. First, the refractive index distribution of the core, side cores, and cladding (i.e., the refractive index distribution of the chiral coupled optical fiber) is measured. Then, the core diameter of the core, the core diameter of the side core, and the spacing between the core and the side core are determined. Using the refractive index and core diameter, the refractive index of the core and side cores corresponding to different modes and wavelengths in the non-twisted structure (i.e., the structure where the side core is parallel to the core) is calculated using the finite element method. A broadband light source is coupled to the chiral coupled optical fiber, and the loss peak of the output spectrum of the chiral coupled optical fiber is measured using a spectrometer. The helical period of the chiral coupled optical fiber is calculated using the refractive index of the core and side core at the loss peak. This method not only avoids the inaccuracy of chiral coupled optical fiber helical period measurement caused by microscopic observation but also avoids the time-consuming problem caused by fiber polishing, thus improving the testing efficiency of the chiral coupled optical fiber helical period and enabling rapid and accurate measurement and determination of the helical period of the chiral coupled optical fiber.
[0036] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 6As shown, the computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs in the non-volatile storage media to run. The database stores data related to the chiral coupled fiber optic spiral period measurement method. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a chiral coupled fiber optic spiral period measurement method.
[0037] Those skilled in the art will understand that Figure 6 The structures shown are merely block diagrams of some structures related to the present application and do not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than shown in the figures, or combine certain components, or have different component arrangements. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.
[0038] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.
[0039] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.
[0040] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.
[0041] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).
[0042] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.
[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0044] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A method for measuring the spiral period of a chiral coupled optical fiber, characterized in that, include: Obtain the refractive index distribution of chiral coupled optical fibers; The core diameter, side core diameter, and spacing between the core and side core of the chiral coupled fiber are determined based on the refractive index distribution of the chiral coupled fiber. The refractive index variation curves of the main core and the straight waveguide side core are determined based on the refractive index distribution of the chiral coupled optical fiber. Obtain the wavelength corresponding to the loss peak; The helical period of the chiral coupled fiber is determined based on the core diameter of the main core, the core diameter of the side core, the spacing between the main core and the side core, the wavelength corresponding to the loss peak, the refractive index variation curve of the main core, and the refractive index variation curve of the straight waveguide side core.
2. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 1, characterized in that, The process of obtaining the refractive index distribution of a chiral coupled fiber includes: The refractive index distribution of chiral coupled optical fibers was measured using the near-field refraction method.
3. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 2, characterized in that, The refractive index distribution of chiral coupled optical fibers was measured using the near-field refraction method, including: Polishing is performed on the hand-coupled optical fiber; The end face of the polished chiral coupled fiber was immersed in a matching liquid with a set refractive index to obtain the near-field light intensity distribution of the chiral coupled fiber. The refractive index distribution of chiral coupled optical fibers is obtained based on the quantitative relationship between light intensity distribution and refractive index in near-field optics.
4. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 1, characterized in that, Based on the refractive index distribution of the chiral coupled fiber, the refractive index variation curves of the core and the straight waveguide side core are determined, including: The refractive index variation curves of the main core and the straight waveguide side core are determined using the finite element method based on the refractive index distribution of the chiral coupled optical fiber.
5. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 1, characterized in that, The helical period of the chiral coupled fiber is determined based on the core diameter of the main core, the core diameter of the side core, the spacing between the main core and the side core, the wavelength corresponding to the loss peak, the refractive index variation curve of the main core, and the refractive index variation curve of the straight waveguide side core, including: The distance between the center point of the main core and the center point of the side core is determined based on the main core diameter, the side core diameter, and the distance between the main core and the side core. The first refractive index is determined based on the wavelength corresponding to the loss peak and the refractive index variation curve of the main core. The second refractive index is determined based on the wavelength corresponding to the loss peak and the refractive index variation curve of the straight waveguide core. The helical period of the chiral coupled optical fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index.
6. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 5, characterized in that, Using formula The helical period of the chiral coupled optical fiber is determined based on the distance between the center point of the main core and the center point of the side core, the first refractive index, and the second refractive index. In the formula, This indicates the helical period of a chiral coupled fiber. This indicates the distance between the center point of the main core and the center point of the side core. Indicates the first refractive index. This indicates the second refractive index.
7. The method for measuring the spiral period of a chiral coupled optical fiber according to claim 1, characterized in that, The process of obtaining the wavelength corresponding to the loss peak includes: Couple a broadband light source into a chiral coupled optical fiber; Obtain the output spectrum of the chiral coupled fiber; The wavelength corresponding to the loss peak is determined based on the output spectrum.
8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the chiral coupled fiber spiral period measurement method according to any one of claims 1-7.
9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the chiral coupling fiber spiral period measurement method according to any one of claims 1-7.
10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the chiral coupling fiber spiral period measurement method according to any one of claims 1-7.