Adaptation method and system of double-fiber collimator and birefringent crystal group

Abstract

The invention is suitable for the technical field of polarization-maintaining optical fiber devices, and provides an adaptation method and system for a double-fiber collimator and a birefringent crystal group, and the adaptation method comprises the steps: judging whether the double-fiber collimator and the birefringent crystal group are adaptive or not according to the ovality of an image generated after two beams of polarized light penetrating through the birefringent crystal group are overlapped, the two beams of polarized light come from the double-fiber collimator; the central axis of the double-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; and controlling the birefringent crystal group to rotate around the central axis of the birefringent crystal group to a position where the double-fiber collimator and the birefringent crystal group can be judged to be adaptive under the condition that the double-fiber collimator and the birefringent crystal group are judged to be not adaptive and have the adaptive position.

Description

Technical Field

[0001] This application belongs to the field of polarization-maintaining fiber optic device technology, and particularly relates to a method and system for adapting a dual-fiber collimator and a birefringent crystal group. Background Technology

[0002] Polarization-maintaining fiber optic devices are widely used in various sectors of the national economy, including aerospace, aviation, marine, industrial manufacturing, and communications. In interferometric fiber optic sensors based on optical coherence detection, the use of polarization-maintaining fibers ensures that the linear polarization direction remains unchanged, improves the coherence signal-to-noise ratio, and enables high-precision measurement of physical quantities.

[0003] A birefringent crystal assembly combines two polarized beams from a two-fiber collimator into a single beam, which is then coupled to a single-fiber collimator, achieving polarization beam combining. To ensure coupling efficiency, the angle between the two beams from the two-fiber collimator and the angle between the two beams generated after splitting by the second birefringent crystal in the birefringent crystal assembly must match; otherwise, the beam cannot be combined. Due to manufacturing tolerances, individual components cannot achieve theoretical consistency. Therefore, birefringent crystal assemblies with different wedge angles need to be selected for matching based on the beam angle of the two-fiber collimator. However, in traditional techniques, the matching efficiency between the two-fiber collimator and the birefringent crystal assembly is low. Summary of the Invention

[0004] This application provides a method and system for adapting a dual-fiber collimator and a birefringent crystal group to improve the adaptation efficiency of the dual-fiber collimator and the birefringent crystal group.

[0005] In a first aspect, embodiments of this application provide a method for adapting a dual-fiber collimator and a birefringent crystal group, including: The ellipticity of the image generated by the overlap of two polarized beams transmitted through the birefringent crystal group is used to determine whether the dual-fiber collimator and the birefringent crystal group are compatible. The two polarized beams are from the dual-fiber collimator. The central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, the birefringent crystal group is controlled to rotate around the central axis of the birefringent crystal group to a position where the dual-fiber collimator and the birefringent crystal group can be determined to be compatible.

[0006] Furthermore, if it is determined that the two-fiber collimator and the birefringent crystal group are not compatible but a compatible position exists, the step of controlling the birefringent crystal group to rotate around its central axis to a position where the compatibility between the two-fiber collimator and the birefringent crystal group can be determined includes: If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, the birefringent crystal group is controlled to rotate around the central axis of the birefringent crystal group; if the ellipticity of the image generated after the two polarized beams transmitted through the birefringent crystal group overlap is higher than the ellipticity threshold, the current rotation position is determined to be the compatible position of the dual-fiber collimator and the birefringent crystal group.

[0007] Secondly, this application provides an adaptation system for a dual-fiber collimator and a birefringent crystal group, including a dual-fiber collimator, a birefringent crystal group, and a spot analyzer; the central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; two beams of polarized light from the dual-fiber collimator are used to pass through the birefringent crystal group and enter the spot analyzer; the spot analyzer is used to analyze the ellipticity of the image generated after the two beams of polarized light passing through the birefringent crystal group overlap to realize the adaptation method.

[0008] Furthermore, the adapter system for the dual-fiber collimator and birefringent crystal group also includes: A transparent tube is movably connected at one end to the light-emitting end of the dual-fiber collimator and fixedly connected at the light-incident end of the birefringent crystal group; the central axis of the transparent tube and the central axis of the birefringent crystal group are on the same straight line. A power unit, connected to the transparent tube, is used to drive the transparent tube to rotate around its central axis, so that the birefringent crystal group rotates around its central axis.

[0009] Furthermore, the adapter system for the dual-fiber collimator and birefringent crystal group also includes: light source; And an optical fiber polarization beam splitter for receiving the light generated by the light source; the optical fiber polarization beam splitter is connected to the light incident end of the dual-fiber collimator via an optical fiber.

[0010] Furthermore, the optical fiber includes a first polarization-maintaining fiber and a second polarization-maintaining fiber; the portions of the first polarization-maintaining fiber and the second polarization-maintaining fiber located within the dual-fiber collimator are parallel to each other.

[0011] Furthermore, the power unit includes an electric rotator; the electric rotator is connected to the transparent tube.

[0012] Furthermore, it also includes a clamp for securing the optical fiber.

[0013] Furthermore, the adaptation system for the dual-fiber collimator and the birefringent crystal group includes a first birefringent crystal and a second birefringent crystal; the crystal wedge angles of the first birefringent crystal and the second birefringent crystal are acute angles.

[0014] Furthermore, the light source is an amplified spontaneous emission light source.

[0015] The beneficial effects of the embodiments of this application compared with the prior art are: This application discloses a method and apparatus for adapting a birefringent crystal group. Based on the ellipticity of the image generated by the overlap of two polarized beams transmitted through the birefringent crystal group, it determines whether a two-fiber collimator and the birefringent crystal group are compatible. If it is determined that the two-fiber collimator and the birefringent crystal group are not compatible but a compatible position exists, the birefringent crystal group is controlled to rotate around its central axis to a position where compatibility can be determined. This application embodiment, by determining the ellipticity of the image generated by the overlap of two polarized beams transmitted through the birefringent crystal group, avoids the inefficiency of manual adjustment and effectively improves the adaptation efficiency of the two-fiber collimator and the birefringent crystal group. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art 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.

[0017] Figure 1 This is a schematic diagram of the structure of the adaptation system for the dual-fiber collimator and birefringent crystal group in related technologies.

[0018] Figure 2 This is a schematic diagram illustrating the adaptation principle of a dual-fiber collimator and a birefringent crystal assembly.

[0019] Figure 3 This is a schematic diagram of the structure of a birefringent crystal group.

[0020] Figure 4 This is a schematic diagram of the three-dimensional structure of a birefringent crystal group.

[0021] Figure 5 This is a schematic flowchart of an embodiment of the adaptation method for a dual-fiber collimator and a birefringent crystal group.

[0022] Figure 6 This is a flowchart illustrating the adaptation method of a dual-fiber collimator and a birefringent crystal group in another embodiment.

[0023] Figure 7 This is a schematic diagram of the structure of an adapter system for a dual-fiber collimator and a birefringent crystal group, according to one embodiment.

[0024] Figure 8 This is a schematic diagram of the adaptation system for a dual-fiber collimator and a birefringent crystal group, according to another embodiment.

[0025] Figure 9 This is a schematic diagram of the light spot image of a dual-fiber collimator and birefringent crystal assembly according to one embodiment.

[0026] Figure 10 This is a schematic diagram of the light spot image of a dual-fiber collimator and a birefringent crystal group, as shown in another embodiment.

[0027] Figure 11 This is a schematic diagram of the light spot image of a dual-fiber collimator and a birefringent crystal group in another embodiment. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0029] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0030] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0032] Polarization-maintaining fiber optic devices are widely used in various sectors of the national economy, including aerospace, aviation, marine, industrial manufacturing, and communications. In interferometric fiber optic sensors based on optical coherence detection, the use of polarization-maintaining fibers ensures that the linear polarization direction remains unchanged, improves the coherence signal-to-noise ratio, and enables high-precision measurement of physical quantities.

[0033] A polarization-maintaining fiber beam splitter (PBS) / polarization-maintaining fiber combiner (PBC) crystal assembly (i.e., a birefringent crystal assembly) consists of a second birefringent crystal and a first birefringent crystal. The birefringent crystal assembly combines the two polarized beams output from the dual-fiber collimator into a single beam, which is then coupled to the single-fiber collimator, achieving polarization combining. To meet coupling efficiency requirements, the angle between the two beams from the dual-fiber collimator and the angle between the two beams generated after splitting by the second birefringent crystal must be matched; otherwise, a single beam cannot be combined. Due to material processing tolerances, individual components cannot achieve theoretical consistency. Therefore, it is necessary to select birefringent crystal assemblies with different wedge angles for matching based on the beam angle of the dual-fiber collimator.

[0034] See Figure 1 As shown, the adaptation system for the dual-fiber collimator and birefringent crystal group in the related technology includes a small glass tube 1, a dual-fiber collimator 2, a birefringent crystal group 3, a large glass tube 4, and a single-fiber collimator 5.

[0035] See Figure 2 As shown, a beam of polarized light enters the fiber capillary 203 of the glass tube 202 from the first polarization-maintaining fiber 204, and another beam of polarized light enters the fiber capillary 203 of the glass tube 202 from the second polarization-maintaining fiber 205. Then, it exits through the lens 201 with a radius of curvature R, and then enters and exits from the birefringent crystal group 3.

[0036] The formula for the angle between the two beams output from the dual-fiber collimator is as follows:

[0037] Where d is the distance between the two optical fibers inside the capillary; n is the refractive index of the lens material; and R is the radius of curvature of the lens. Individual differences in the radius of curvature R of lens 201 and the fiber spacing d will cause the beam angle. The differences.

[0038] See the structure of birefringent crystal group 3. Figure 3 As shown. The birefringent crystal group 3 includes a second birefringent crystal 302 and a first birefringent crystal 301. See reference. Figure 4 As shown. The first optical axis 303 of the first birefringent crystal 301 and the second optical axis 304 of the second birefringent crystal 302 are perpendicular to each other. The central axis 305 of the birefringent crystal group 3 passes through two opposite surfaces of the second and first birefringent crystals. a1 is the crystal wedge angle of the second birefringent crystal 302, and a2 is the crystal wedge angle of the first birefringent crystal 301. The formula for the angle between the two polarized beams entering the second birefringent crystal is as follows:

[0039] Where n o -n e It is the birefringence of crystalline materials. It's the crystal wedge angle. Theoretically speaking, =a1=a2, due to processing errors, there is a certain deviation between a1 and a2.

[0040] Theoretically, the compatibility between a two-fiber collimator and a birefringent crystal assembly needs to ensure... and The consistency is good, but due to the processing tolerances of the materials, and Angle deviations can directly cause optical path mismatches, resulting in device losses, so adaptation is necessary.

[0041] However, in traditional technologies, the adaptation efficiency for dual-fiber collimators and birefringent crystal groups is low.

[0042] To improve the adaptation efficiency of a dual-fiber collimator and a birefringent crystal group, in a first aspect, embodiments of this application provide a method for adapting a dual-fiber collimator and a birefringent crystal group. This method can run on a computer or on other devices. These other devices can be mobile phones, tablets, wearable devices, in-vehicle devices, augmented reality (AR) / virtual reality (VR) devices, laptops, ultra-mobile personal computers (UMPCs), netbooks, personal digital assistants (PDAs), and other terminal devices. Embodiments of this application do not impose any restrictions on the specific type of terminal device.

[0043] For example, the terminal device may be a station (STAION, ST) in a WLAN, a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA) device, a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, an in-vehicle device, a vehicle networking terminal, a computer, a laptop computer, a handheld communication device, a handheld computing device, a satellite wireless device, a wireless modem card, a set-top box (STB), customer premises equipment (CPE), and / or other devices used for communication over a wireless system, as well as next-generation communication systems, such as mobile terminals in 5G networks or mobile terminals in future evolved Public Land Mobile Network (PLMN) networks.

[0044] As an example and not a limitation, when the terminal device is a wearable device, the term "wearable device" can also refer to any device that utilizes wearable technology to intelligently design and develop everyday wearables, such as glasses, gloves, watches, clothing, and shoes. Wearable devices are portable devices worn directly on the body or integrated into a user's clothing or accessories. Wearable devices are not merely hardware devices; they achieve powerful functions through software support, data interaction, and cloud interaction. Broadly defined, wearable smart devices include those with comprehensive functions, large sizes, and the ability to perform complete or partial functions without relying on a smartphone, such as smartwatches or smart glasses, as well as those focused on a specific application function that require interaction with other devices such as smartphones, such as various smart bracelets and smart jewelry for vital sign monitoring.

[0045] For the fitting method of the two-fiber collimator and the birefringent crystal group, please refer to [link / reference]. Figure 5 As shown, it includes: S1. Based on the ellipticity of the image generated by the overlap of the two polarized beams transmitted through the birefringent crystal group, determine whether the two-fiber collimator and the birefringent crystal group are compatible, wherein the two polarized beams originate from the two-fiber collimator; the central axis of the two-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; A two-fiber collimator typically has two optical fibers, each capable of outputting a beam of light. The light generated by the light source and fiber polarization beam splitter exits the two-fiber collimator, forming beams with an angled beam. Two beams of polarized light are used. When the central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are collinear, the polarization direction of the polarized light from the dual-fiber collimator and the optical axis of the birefringent crystal are in the same direction. Light can propagate in a straight line, reducing scattering and loss, and allowing the detected ellipticity to accurately reflect the fit between the dual-fiber collimator and the birefringent crystal group. Therefore, the fit is determined by detecting the ellipticity of the image generated after the two beams of polarized light emitted from the dual-fiber collimator and transmitted through the birefringent crystal group overlap.

[0046] It is understandable that when two beams of polarized light from the dual-fiber collimator enter the birefringent crystal group, if the two beams are not on the optical axis of the birefringent crystal group, four light spots can be generated on the spot analyzer, and the ellipticity value is given; if the two beams of polarized light are on the optical axis of the birefringent crystal group, and the birefringent crystal group and the dual-fiber collimator are not compatible, two light spots can be generated on the spot analyzer, and the ellipticity value is given; if the two beams of polarized light are on the optical axis of the birefringent crystal group and the crystal wedge angle of the birefringent crystal group is compatible with the dual-fiber collimator, they can overlap to form a single light spot image on the spot analyzer, and the ellipticity value of the image generated after overlap is given; by analyzing the above cases, the compatibility between the birefringent crystal group and the dual-fiber collimator can be determined based on the ellipticity value.

[0047] S2. If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, control the birefringent crystal group to rotate around the central axis of the birefringent crystal group to a position where the dual-fiber collimator and the birefringent crystal group can be determined to be compatible.

[0048] When it is determined that the two-fiber collimator and the birefringent crystal assembly are mismatched but a suitable position exists, it means that their current relative position or angle cannot guarantee that the optical signal will be transmitted in an ideal polarization state. This may lead to increased optical signal loss and deterioration of the polarization state, thereby affecting the performance and stability of the entire optical system. Therefore, measures need to be taken to adjust their relative position or angle to achieve a suitable state. Controlling the rotation of the birefringent crystal assembly around its central axis can change the relative angle between the birefringent crystal assembly and the two-fiber collimator, thereby optimizing the light transmission path and polarization state preservation effect.

[0049] A power device (such as a rotation control device) can be used to control the rotation of the birefringent crystal assembly around its central axis. While rotating the birefringent crystal assembly, the ellipticity of the image generated by the overlap of the two polarized beams transmitted through it is continuously monitored. The rotation angle is continuously changed, and the changes in ellipticity are observed. When the ellipticity reaches or exceeds a preset ellipticity threshold, it indicates that the current rotation position has achieved a proper fit between the dual-fiber collimator and the birefringent crystal assembly, at which point rotation is stopped.

[0050] The above technical solution, by detecting the key parameter of the ellipticity of the image generated after the two polarized beams of light passing through the birefringent crystal group overlap, can accurately determine whether the dual-fiber collimator and the birefringent crystal group are compatible using quantitative indicators. Compared with traditional methods that may rely on experience or simple visual inspection, this determination method based on optical ellipticity is more scientific and accurate, effectively avoiding the problem of increased signal transmission loss due to poor compatibility.

[0051] Clear and quantifiable criteria make the adaptation process more efficient. Staff do not need to spend a lot of time on repeated debugging and subjective judgment; they can quickly determine the adaptation status based on the ellipticity detection results, which greatly shortens the adaptation time, improves overall work efficiency, and reduces labor and time costs.

[0052] Therefore, by determining the ellipticity of the image generated after the two polarized beams of light passing through the birefringent crystal group are superimposed, the embodiments of this application effectively improve the adaptation efficiency of the dual-fiber collimator and the birefringent crystal group.

[0053] For further details, please refer to [link / reference]. Figure 6 As shown, when it is determined that the two-fiber collimator and the birefringent crystal group are not compatible and a compatible position exists, controlling the birefringent crystal group to rotate around the central axis of the birefringent crystal group to a position where the compatibility between the two-fiber collimator and the birefringent crystal group can be determined includes: S21. If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, control the birefringent crystal group to rotate around the central axis of the birefringent crystal group; if the ellipticity of the image generated after the two polarized beams transmitted through the birefringent crystal group overlap is higher than the ellipticity threshold, determine that the current rotated position is the compatible position of the dual-fiber collimator and the birefringent crystal group.

[0054] By controlling the birefringent crystal group to rotate around the central axis and determining the ellipticity of the transmitted polarized light, the matching position of the dual-fiber collimator and the birefringent crystal group can be accurately found, ensuring that the two achieve the best coupling state, effectively reducing the loss of optical signals during transmission, and improving the transmission efficiency and stability of the optical communication system.

[0055] By combining rotation operation with ellipticity determination, the automatic detection and determination of the fitting position is achieved. Compared with traditional methods that rely on manual experience or tedious testing, the detection efficiency is greatly improved, the system setup or debugging time is shortened, and the labor and time costs are reduced.

[0056] By using an ellipticity greater than the ellipticity threshold as the basis for determining the fit position, the originally ambiguous fit judgment is transformed into a judgment process with clear quantitative standards, making the judgment results more objective and accurate, reducing errors caused by human factors and subjective judgment, and improving the reliability and consistency of the entire system.

[0057] Optionally, the ellipticity threshold is 95%.

[0058] By controlling the rotation of the birefringent crystal group around its central axis, the propagation path and interaction mode of the two polarized beams within the crystal group can be actively altered, thereby finely adjusting the ellipticity of the polarized light. This active adjustment mechanism allows for the possibility of achieving a fit standard (ellipticity greater than 95%) in cases where the initial state may be incompatible or the ellipticity is substandard, through rotational operations. This enables rapid adaptation of the two-fiber collimator and the birefringent crystal group.

[0059] In actual manufacturing and assembly processes, dual-fiber collimators and birefringent crystal assemblies inevitably contain certain errors, such as errors in the processing precision of optical components and angular deviations during assembly. These errors may lead to unsatisfactory ellipticity in the image generated after the two polarized beams overlap, affecting the fitting effect. By changing and adjusting the wedge angle of the crystal assembly, the effects of these errors can be offset or reduced, restoring the ellipticity of the polarized light to an ideal level and achieving high-precision fitting.

[0060] High-precision adaptation reduces the impact of external interference on optical signals, thereby lowering the failure rate caused by adaptation issues or signal quality degradation. This helps extend the lifespan of various optical components in the system, reduces the frequency of equipment maintenance and replacement, improves system availability and reliability, and lowers system operating costs.

[0061] Secondly, embodiments of this application provide an adapter system 400 for a dual-fiber collimator and a birefringent crystal group, see reference. Figure 7 As shown, it includes: The first control unit 402 is used to implement the adaptation method of the dual-fiber collimator and the birefringent crystal group.

[0062] The first acquisition unit 401 is connected to the first control unit 402 and is used to acquire the ellipticity of the image generated after the two polarized beams of light passing through the birefringent crystal group overlap.

[0063] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0064] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments of this application can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying the computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0065] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0066] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0067] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0068] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the technical solution in this embodiment, depending on actual needs.

[0069] Thirdly, embodiments of this application provide an adapter system for a dual-fiber collimator and a birefringent crystal group, see reference. Figure 8 As shown, it includes a dual-fiber collimator, a birefringent crystal group, and a spot analyzer; the central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; two beams of polarized light from the dual-fiber collimator are used to pass through the birefringent crystal group and enter the spot analyzer; the spot analyzer is used to analyze the ellipticity of the image generated after the two beams of polarized light passing through the birefringent crystal group overlap to realize the adaptation method.

[0070] See Figure 8 As shown, the adapter device for the dual-fiber collimator and birefringent crystal group includes a dual-fiber collimator 2, a birefringent crystal group 3, and a spot analyzer 06; the central axis 305 of the dual-fiber collimator 2 and the birefringent crystal group 07 is on the same straight line; two beams of polarized light are incident on the spot analyzer through the dual-fiber collimator 2 and the birefringent crystal group 3, and the spot analyzer analyzes the ellipticity of the image generated after the two beams of polarized light passing through the birefringent crystal group overlap.

[0071] Traditional polarization state detection methods (such as polarizer + power meter combination) can only obtain the polarization extinction ratio (ER) or polarization direction angle (θ), and cannot fully describe the elliptic characteristics of polarized light (major axis / minor axis ratio, rotation angle). However, the spot analyzer, through holographic grating beam splitting + CCD imaging technology, can simultaneously capture the intensity distribution and phase information of polarized light, and achieve sub-pixel precision quantization of ellipticity parameters (major axis a, minor axis b, rotation angle ψ).

[0072] During transmission, birefringent crystal arrays may experience spatial spot distortion (such as a shift in the major axis of an elliptical spot) due to inhomogeneous birefringence or mechanical stress caused by inhomogeneous birefringence or mechanical stress. Spot analyzers, by simultaneously monitoring the spot morphology and polarization state, can separate the contributions of spatial and polarization mismatches in real time, providing accurate data for closed-loop compensation.

[0073] Furthermore, the adapter system for the dual-fiber collimator and the birefringent crystal group also includes a transparent tube and a power device; one end of the transparent tube is movably connected to the light emitting end of the dual-fiber collimator, and the other end of the transparent tube is fixedly connected to the light incident end of the birefringent crystal group; the central axis of the transparent tube and the central axis of the birefringent crystal group are on the same straight line; the power device is connected to the transparent tube, and the power device is used to drive the transparent tube to rotate around the central axis of the transparent tube, so that the birefringent crystal group rotates around the central axis of the birefringent crystal group.

[0074] Specifically, see Figure 8 As shown, the adapter device for the dual-fiber collimator and the birefringent crystal group also includes a transparent tube 05 and a power device 04; the left end of the transparent tube 05 is movably connected to the light emitting end of the dual-fiber collimator 2, and the right end of the transparent tube 05 is fixedly connected to the light incident end of the birefringent crystal group 3; the power device 04 is connected to the transparent tube 05, and the power device 04 is used to drive the transparent tube 05 to rotate around the central axis, so that the birefringent crystal group rotates around the central axis.

[0075] Furthermore, the adaptation system for the dual-fiber collimator and birefringent crystal group also includes a light source and a fiber polarization beamsplitter, the fiber polarization beamsplitter being used to receive the light generated by the light source; the fiber polarization beamsplitter is connected to the light incident end of the dual-fiber collimator via an optical fiber. See also... Figure 8 As shown, the adapter device for the dual-fiber collimator and birefringent crystal group also includes a light source 01 and an optical fiber polarization beam splitter 02; the optical fiber polarization beam splitter 02 is used to connect to the light source 01; the optical fiber polarization beam splitter is connected to the light incident end of the dual-fiber collimator 2 through an optical fiber.

[0076] Furthermore, the optical fiber includes a first polarization-maintaining fiber 07 and a second polarization-maintaining fiber 08; the portions of the first polarization-maintaining fiber and the second polarization-maintaining fiber located within the dual-fiber collimator are parallel to each other.

[0077] Furthermore, the power unit includes an electric rotator; the electric rotator is connected to the transparent tube. The adapter system for the dual-fiber collimator and birefringent crystal group also includes clamps for fixing the optical fiber. The birefringent crystal group includes a first birefringent crystal and a second birefringent crystal; the crystal wedge angles of the first birefringent crystal and the second birefringent crystal are acute angles. The light source is an amplified spontaneous emission source.

[0078] See Figure 8 As shown, the optical fiber includes a first polarization-maintaining fiber 07 and a second polarization-maintaining fiber 08; the portions of the first and second polarization-maintaining fibers located within the dual-fiber collimator are parallel to each other; the power device includes an electric rotator; and also includes a clamp 03 for fixing the optical fiber; exemplary, the fiber polarization beam splitter outputs two beams of linearly polarized light, and the clamp 03 temporarily aligns the polarization axes to ensure that the linearly polarized light generated by the fiber polarization beam splitter 02 propagates along the slow axis within the optical fiber of the dual-fiber collimator 2. The birefringent crystal group includes a first birefringent crystal and a second birefringent crystal; the crystal wedge angles of the first and second birefringent crystals are acute angles; the light source is an amplified spontaneous emission source.

[0079] For example, see Figure 8 As shown, the light emitted from the light source 01 is processed by the fiber polarization beam splitter 02 to generate two polarized beams, which enter the light incident end of the dual-fiber collimator 2 through the first polarization-maintaining fiber 07 and the second polarization-maintaining fiber 08, respectively. Optionally, the two polarized beams are two linearly polarized beams. The first polarization-maintaining fiber 07 and the second polarization-maintaining fiber 08 are fixed by a clamp 03, which is a temporary alignment clamp for the polarization-maintaining fiber. The clamp 03 and the fiber polarization beam splitter 02 enable the first polarization-maintaining fiber 07 and the second polarization-maintaining fiber 08 to be temporarily polarized and aligned, ensuring that the linearly polarized light is transmitted along the slow axis in the first polarization-maintaining fiber 07 and the second polarization-maintaining fiber 08.

[0080] In use, the birefringent crystal assembly to be adapted is pre-installed and fixed on the right end of the transparent tube 05, and a dual-fiber collimator is movably connected to the left end of the transparent tube. The power unit is connected to the outside of the transparent tube 05 and is used to drive the transparent tube to rotate around the central axis 305. Under random conditions, the spot analyzer will receive the spot of four beams of light from the birefringent crystal assembly. If the collimator and the crystal assembly are well angularly matched, the four beams of light will be combined into one beam when rotated to a certain angle. The spot analyzer detects the ellipticity of the combined light spot to determine whether it exceeds the ellipticity threshold, thus realizing the above-mentioned adaptation method.

[0081] The technical solution and method for the adaptation system of the dual-fiber collimator and birefringent crystal group are similar, and will not be described in detail here.

[0082] For example, the adapter includes an ASE light source, a fiber polarization beam splitter, two polarization-maintaining fiber temporary alignment clamps, a beam analyzer, and an electric rotator. After passing through the fiber polarization beam splitter, the light from the ASE light source is divided into two polarized beams that propagate along the slow axis in two separate output fibers. The two output fibers are respectively mounted and fixed on the two polarization-maintaining fiber temporary alignment clamps. When testing the birefringent crystal assembly with the dual-fiber collimator, the following procedures should be followed: (1) Two pigtails are respectively installed and fixed on the polarization-maintaining temporary alignment clamp, and temporarily aligned with the two optical fibers output by the fiber polarization beam splitter to ensure that the linearly polarized light is transmitted along the slow axis in the fiber of the dual-fiber collimator. (2) The birefringent crystal assembly to be adapted is pre-installed and fixed on the glass tube, and a double fiber collimator is fitted onto the glass tube; (3) The electric rotator clamps the glass tube and drives the glass tube to move in accordance with the law. Figure 8 Rotate one full circle in the indicated direction to find the suitable position; (4) The spot analyzer detects the spot output by the birefringent crystal group; under random conditions, the beam output by the birefringent crystal group is four beams, which can form a spot of four beams. The spot analyzer receives the spot of four beams from the birefringent crystal group. If the wedge angle of the dual-fiber collimator and the birefringent crystal group is well matched, the four beams will be combined into one beam when rotated to a certain angle. The spot analyzer detects the ellipticity of the spot of the combined light and determines whether it exceeds the ellipticity threshold, thus realizing the above-mentioned adaptation method.

[0083] It is understood that the degree of fit between the dual-fiber collimator and the birefringent crystal group in the embodiments of this application can be determined by the ellipticity of the beam after it is synthesized.

[0084] (5) When the ellipticity of the spot of four beams combined into one beam is detected to be greater than 95%, a high ellipticity indicates that the beams overlap well and the angles match well.

[0085] Using the above-mentioned fitting device and method for the dual-fiber collimator and birefringent crystal group, and with the dual-fiber spacing of the tail fiber in the dual-fiber collimator being 143 μm, the crystal combinations with different crystal wedge angles in the birefringent crystal group were tested. The fitting results are shown in Table 1 below.

[0086] Table 1

[0087] As shown in Table 1, a pigtail with a spacing of 143µm and wedge angles of 8.2° and 8.3° can form a beam with a suitable ellipticity, and the corresponding loss also meets the requirements.

[0088] For example, the combination of the double-fiber collimator and the birefringent crystal group in serial numbers 3, 5 and 6 is used to illustrate the trial fitting.

[0089] For the combination numbered 3, please refer to the specific operating conditions of the spot analyzer. Figure 9 As shown in Table 2.

[0090] Table 2

[0091] according to Figure 9 As shown in Table 2, this combination has good angle matching, beam overlap, and ellipticity.

[0092] For the combination numbered 5, please refer to the specific operating conditions of the spot analyzer. Figure 10 As shown in Table 3.

[0093] Table 3

[0094] according to Figure 10 As shown in Table 3, the angles of this combination are mismatched, and the beam overlap ellipticity is poor.

[0095] For the combination numbered 6, please refer to the specific operating conditions of the spot analyzer. Figure 11 As shown in Table 4.

[0096] Table 4

[0097] according to Figure 11 As shown in Table 4, the angle matching is poor, and the beams do not overlap at all.

[0098] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for adapting a two-fiber collimator and a birefringent crystal assembly, characterized in that, include: The ellipticity of the image generated by the overlap of two polarized beams transmitted through the birefringent crystal group is used to determine whether the dual-fiber collimator and the birefringent crystal group are compatible. The two polarized beams are from the dual-fiber collimator. The central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, the birefringent crystal group is controlled to rotate around the central axis of the birefringent crystal group to a position where the dual-fiber collimator and the birefringent crystal group can be determined to be compatible.

2. The method for adapting a birefringent crystal group according to claim 1, characterized in that, When it is determined that the two-fiber collimator and the birefringent crystal assembly are mismatched but a matching position exists, controlling the birefringent crystal assembly to rotate around its central axis to a position where the two-fiber collimator and the birefringent crystal assembly can be determined to be compatible includes: If it is determined that the dual-fiber collimator and the birefringent crystal group are not compatible and there is a compatible position, the birefringent crystal group is controlled to rotate around the central axis of the birefringent crystal group; if the ellipticity of the image generated after the two polarized beams transmitted through the birefringent crystal group overlap is higher than the ellipticity threshold, the current rotation position is determined to be the compatible position of the dual-fiber collimator and the birefringent crystal group.

3. A matching system for a dual-fiber collimator and a birefringent crystal assembly, characterized in that, The device includes a dual-fiber collimator, a birefringent crystal group, and a spot analyzer; the central axis of the dual-fiber collimator and the central axis of the birefringent crystal group are on the same straight line; two beams of polarized light from the dual-fiber collimator are used to pass through the birefringent crystal group and enter the spot analyzer; the spot analyzer is used to analyze the ellipticity of the image generated after the two beams of polarized light passing through the birefringent crystal group overlap to achieve the adaptation method according to any one of claims 1-2.

4. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 3, characterized in that, Also includes: A transparent tube is movably connected at one end to the light-emitting end of the dual-fiber collimator and fixedly connected at the light-incident end of the birefringent crystal group; the central axis of the transparent tube and the central axis of the birefringent crystal group are on the same straight line. A power unit, connected to the transparent tube, is used to drive the transparent tube to rotate around its central axis, so that the birefringent crystal group rotates around its central axis.

5. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 4, characterized in that, Also includes: light source; And an optical fiber polarization beam splitter for receiving the light generated by the light source; The fiber polarization beam splitter is connected to the light incident end of the dual-fiber collimator via an optical fiber.

6. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 5, characterized in that, The optical fiber includes a first polarization-maintaining fiber and a second polarization-maintaining fiber; the portions of the first polarization-maintaining fiber and the second polarization-maintaining fiber located within the dual-fiber collimator are parallel to each other.

7. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 5, characterized in that, The power unit includes an electric rotator; the electric rotator is connected to the transparent tube.

8. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 5, characterized in that, It also includes clamps for securing the optical fiber.

9. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 5, characterized in that, The birefringent crystal group includes a first birefringent crystal and a second birefringent crystal; the crystal wedge angles of the first birefringent crystal and the second birefringent crystal are acute angles.

10. The adaptation system for the dual-fiber collimator and birefringent crystal group according to claim 5, characterized in that, The light source is an amplified spontaneous emission light source.

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