A method and system for aligning polarization axes of polarization maintaining optical fibers in a fiber array

Abstract

The present application relates to the technical field of optical fiber polarization axis alignment adjustment, and particularly provides a polarization maintaining optical fiber polarization axis alignment adjustment method and system for optical fiber array, which comprises: obtaining initial polarization axis azimuth angle data of each core in the polarization maintaining optical fiber array at the incident end face; using an image processing algorithm to perform polarization axis backtracking calibration on the exit end face of the polarization maintaining optical fiber array, and determining the actual spatial pose of the polarization axis of each core at the exit end face; generating an independent pre-twist compensation parameter set for each core according to the actual spatial poses of the polarization axes corresponding to the plurality of cores; using the independent pre-twist compensation parameter set to perform an angular pre-twist operation on each core one by one during the optical fiber array axis assembly process, and determining the target polarization axis alignment attitude of each core before curing; curing and shaping the optical fiber array in the target polarization axis alignment attitude to obtain a cured polarization maintaining optical fiber array assembly. The present application realizes the polarization axis stability control of the optical fiber array from the free state to the cured state.

Description

Technical Field

[0001] This invention relates to the field of fiber polarization axis alignment and adjustment technology, and in particular to a method and system for aligning the polarization axis of polarization-maintaining fibers in a fiber array. Background Technology

[0002] Polarization-maintaining fiber is a special type of optical fiber with strong birefringence, capable of maintaining the polarization state of linearly polarized light without degradation during transmission. It is widely used in fiber optic sensing, fiber optic communication, fiber optic gyroscopes, fiber optic current transformers, and coherent optical communication. In many applications, multiple polarization-maintaining fibers are often arranged in parallel at predetermined intervals and fixed on a V-groove substrate to form a polarization-maintaining fiber array assembly, used in polarization-maintaining waveguide devices, polarization-maintaining collimator arrays, and multi-channel optical modules.

[0003] In the manufacturing process of polarization-maintaining fiber arrays, polarization axis alignment is a critical step that determines device performance. Polarization-maintaining fibers rely on the birefringence effect generated by the stress region around the fiber core to maintain the polarization state. Linearly polarized light must be injected along the fast or slow axis to maintain stable transmission. Therefore, before fixing the polarization-maintaining fiber to the V-groove substrate, the polarization axis of each fiber, i.e., the direction of the line connecting the centers of the two stress regions, must be adjusted to a specified angle, and it must be ensured that this angle still meets the design requirements after curing and shaping.

[0004] However, aligning the polarization axis of a polarization-maintaining fiber array faces multiple technical challenges. First, the parallel arrangement of multiple fiber cores necessitates independent adjustment of the polarization axis of each fiber, and the more channels the array has (e.g., 8, 12, 16, or even 32 channels and above), the greater the adjustment difficulty. Second, fixing the fiber in the V-groove substrate typically relies on UV-curable or thermosetting adhesives. During the curing process, the adhesive undergoes volume shrinkage, applying a tangential torque to the fiber. Simultaneously, during the baking and thermosetting process, the mismatch in the thermal expansion coefficients of the ferrule and the fiber can lead to submicron-level relative slippage. Both of these factors constitute the main physical cause of angular drift of the polarization axis. Even if the polarization axis is precisely aligned before curing, significant angular displacement may still occur after curing, severely affecting the extinction ratio performance of the device.

[0005] Existing technologies cannot effectively compensate for polarization axis drift caused by curing stress, lack targeted compensation for the differential deformation of multiple fiber cores, lack a stress gradient release mechanism in the curing process, are highly dependent on manual operation, have unstable axis fixation quality, and lack full-process traceability and quantitative description of polarization axis status.

[0006] In view of the shortcomings of the prior art, the main technical problem to be solved by the present invention is: how to eliminate the uncontrollable angular drift of the polarization axis caused by the combined effect of adhesive curing shrinkage stress and thermal mismatch sliding during the curing and shaping process of polarization-maintaining fiber array, and achieve high-precision stability control of the polarization axis of each fiber core from the free state to the cured state. Summary of the Invention

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In one aspect, the present invention provides a method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array, comprising the following steps: Acquire the initial polarization axis azimuth angle data of each fiber core in the polarization-maintaining fiber array at the incident end face; wherein, the initial polarization axis azimuth angle data includes the angular distribution measurement values ​​of the fast axis or slow axis of each fiber core relative to the array reference plane; For each initial polarization axis azimuth angle data, an image processing algorithm is used to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array to determine the actual spatial pose of the polarization axis of each fiber core at the output end face; wherein, the actual spatial pose of the polarization axis is used to describe the angular offset of the polarization axis of each fiber core at the output end face and the fiber core rotation trend vector in a three-dimensional coordinate system. Based on the actual spatial poses of multiple polarization axes corresponding to multiple fiber cores, an independent pre-torsion compensation parameter set is generated for each fiber core. The independent pre-torsion compensation parameter set includes angular presets for reverse compensation of curing shrinkage stress and thermal mismatch slip. Using the independent pre-torsion compensation parameter set, angular pre-torsion operations are performed on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. The target polarization axis alignment posture includes the polarization axis angular pre-bias angle of each fiber core before curing trigger. A multi-temperature zone stepped curing process was used to cure and shape the fiber array in the target polarization axis alignment posture, resulting in a polarization-maintaining fiber array component with a polarization axis angular drift of each fiber core of less than or equal to ±0.3° after curing.

[0008] Another aspect of the present invention provides an assembly and adjustment system for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array, comprising: The azimuth data acquisition module is used to acquire the initial polarization axis azimuth data of each fiber core in the polarization-maintaining fiber array at the incident end face; wherein, the initial polarization axis azimuth data includes the angular distribution measurement values ​​of the fast axis or slow axis of each fiber core relative to the array reference plane; The spatial pose determination module is used to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array using image processing algorithms based on the initial polarization axis azimuth angle data, and to determine the actual spatial pose of the polarization axis of each fiber core at the output end face; wherein, the actual spatial pose of the polarization axis is used to describe the angular offset of the polarization axis of each fiber core at the output end face and the fiber core rotation trend vector in a three-dimensional coordinate system. The pre-torsion operation module is used to generate an independent pre-torsion compensation parameter set for each fiber core based on the actual spatial pose of multiple polarization axes corresponding to multiple fiber cores. The independent pre-torsion compensation parameter set includes angular presets for reverse compensation of curing shrinkage stress and thermal mismatch slip. Using the independent pre-torsion compensation parameter set, angular pre-torsion operations are performed on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. The target polarization axis alignment posture includes the polarization axis angular pre-bias angle of each fiber core before curing triggering. The curing and shaping module is used to cure and shape the fiber array in the target polarization axis alignment posture using a multi-temperature zone stepped curing process, so as to obtain a polarization-maintaining fiber array component with a polarization axis angular drift of each fiber core less than or equal to ±0.3° after curing.

[0009] The technical features of this invention in acquiring initial polarization axis azimuth data provide a reference for polarization axis alignment, ensuring that calibration operations are based on accurate initial angular distribution measurements. By quantifying the angular deviation of each fiber core's fast or slow axis relative to the array reference surface, it lays the data foundation for polarization axis tracing. The technical features of polarization axis tracing calibration utilize image processing algorithms to achieve three-dimensional reconstruction of the spatial pose of the polarization axis at the exit end face; it can accurately describe the angular offset and rotation trend vector, overcoming the limitation of traditional methods in quantifying the dynamic rotation of the fiber core, and providing high-precision input parameters for pre-torsion compensation. The technical feature of generating an independent pre-torsion compensation parameter set performs mechanical modeling and reverse compensation for curing shrinkage stress and thermal mismatch slippage; by using angular presets, it achieves accurate prediction of differentiated deformation of different fiber cores, and combined with sequentially executed angular pre-torsion operations, it enables pre-compensation of thermomechanical stress in the target polarization axis alignment posture before curing. The multi-temperature zone stepped curing process is characterized by suppressing the accumulation of non-uniform stress during the curing process through a controllable gradient temperature field. In synergy with the pre-torsion compensation parameters, the final polarization axis angular drift is controlled within ±0.3°, meeting the stringent requirements of polarization-maintaining fiber array components for polarization retention performance. Attached Figure Description

[0010] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the assembly and adjustment method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array, as provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the assembly and adjustment method for aligning the polarization axis of the polarization-maintaining fiber in the fiber array provided in Embodiment 1 of the present invention; Figure 3 This is a block diagram of the assembly and adjustment system for aligning the polarization axis of the polarization-maintaining fiber in the fiber array provided in Embodiment 6 of the present invention; Figure 4 A block diagram of the electronic device provided by the present invention; Figure 5 A block diagram of a computer-readable storage medium provided for this invention. Detailed Implementation

[0011] The technical solutions of the present invention will now be described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0012] Hereinafter, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or the number of technical features explicitly shown. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0013] In this invention, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed mechanical connection, a detachable mechanical connection, or an integral part; or, "connection" can be a direct connection or an indirect connection through an intermediate medium. Furthermore, unless otherwise explicitly specified and limited, the term "coupling" should be interpreted broadly. For example, "coupling" can be a direct electrical connection, such as physical contact and electrical conduction between two components; it can also be understood as an electrical connection between different components in a circuit structure through physical lines capable of transmitting electrical signals, such as copper foil or wires on a printed circuit board (PCB), to transmit electrical signals; or, "coupling" can be an indirect electrical connection between two components through an intermediate medium; or, "coupling" can be an electrical connection between two components in a non-contact manner, such as an electrical connection between two components using capacitive coupling to transmit electrical signals.

[0014] In this embodiment of the invention, directional terms such as "up," "down," "left," and "right" may be defined relative to the orientation of the components shown in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0015] Example 1: As Figure 1 As shown, this embodiment of the invention provides a method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array, comprising the following steps: Step S100: Obtain the initial polarization axis azimuth angle data of each fiber core in the polarization-maintaining fiber array at the incident end face; wherein, the initial polarization axis azimuth angle data includes the angular distribution measurement values ​​of the fast axis or slow axis of each fiber core relative to the array reference plane; The polarization-maintaining fiber array is fixed on a V-groove substrate and vacuum-adsorbed to acquire images of the incident end face. The center coordinates of the two stress regions of each fiber core are identified by adaptive threshold segmentation and concentric circle weighted average positioning. The polarization axis direction is determined based on the line connecting the centers of the two stress regions. The angular offset of the polarization axis of each fiber core relative to the array reference reference surface is calculated with the array reference reference surface as the zero position to obtain the initial polarization axis azimuth angle distribution data. For each fiber core, perform the following angular offset calculation operation: Based on the determined coordinates of the centers of two stress zones on the same fiber core end face, denoted as... and Calculate the orientation angle of the polarization axis of the fiber core in the image coordinate system. Direction angle It is obtained by solving for the arctangent value corresponding to the slope of the line connecting the two center points, i.e. / ( - The angles are then normalized to the quadrants to map them to the preset range of 0° to 180°. Obtain the linear feature angle corresponding to the array reference plane in the end face image. , It is extracted from the substrate reference edge or preset marker line marked in the image by straight line fitting; Calculate the angular offset of each fiber core. and to Modulus correction is performed to ensure that the value falls within the target angle measurement range, such as -90° to +90° or 0° to 180°, in order to eliminate periodic repetitive interference. The calculated The initial polarization axis azimuth angle data of the fiber core is recorded, and a sequence of angular distribution measurement values ​​is formed according to the fiber core number, which serves as the input reference for polarization axis traceability calibration.

[0016] Step S200: For each initial polarization axis azimuth angle data, use image processing algorithms to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array, and determine the actual spatial pose of the polarization axis of each fiber core at the output end face; wherein, the actual spatial pose of the polarization axis is used to describe the angular offset of the polarization axis of each fiber core at the output end face and the fiber core rotation trend vector in a three-dimensional coordinate system. Step S300: Based on the actual spatial poses of multiple polarization axes corresponding to multiple fiber cores, generate an independent pre-torsion compensation parameter set for each fiber core. The independent pre-torsion compensation parameter set includes angular presets for reverse compensation of curing shrinkage stress and thermal mismatch slippage. Using the independent pre-torsion compensation parameter set, perform angular pre-torsion operations on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. The target polarization axis alignment posture includes the polarization axis angular pre-bias angle of each fiber core before curing triggering. Step S400: The fiber array in the target polarization axis alignment position is cured and shaped using a multi-temperature zone stepped curing process to obtain a polarization-maintaining fiber array component with a polarization axis angular drift of each fiber core less than or equal to ±0.3° after curing.

[0017] The polarization-maintaining fiber array is an optical fiber assembly formed by arranging multiple polarization-maintaining fibers in parallel at predetermined intervals and fixing them on a V-groove substrate. It is used in polarization-maintaining waveguide devices, polarization-maintaining collimator arrays, and multi-channel optical modules. The fiber core is the central light transmission region of the polarization-maintaining fiber. Linearly polarized light propagates along the fiber core, and its polarization state is maintained by the birefringence effect generated by the stress regions around the fiber core. The incident end face is the end face where light enters the polarization-maintaining fiber array, used to obtain the initial polarization axis azimuth angle data of each fiber core. The fast axis or slow axis are two orthogonal polarization transmission axes generated by the birefringence effect in the polarization-maintaining fiber. The fast axis is the direction with a lower refractive index, where the light propagates faster and passes perpendicularly through the midpoint of the line connecting the centers of the two stress regions; the slow axis is the direction with a higher refractive index, where the light propagates slower and passes through the line connecting the centers of the two stress regions. The array reference plane is a physical reference plane set on the fiber array substrate, serving as an absolute zero-degree reference for measuring the angular distribution of the polarization axes of each fiber core. The angular distribution measurement values ​​are the angular offsets of the fast or slow axis of each fiber core relative to the array reference plane, expressed in degrees (°). The exit end face is the end face from which light rays emerge in the polarization-maintaining fiber array, which is ground and polished for polarization axis tracing calibration. Polarization axis tracing calibration involves analyzing the image of the exit end face using image processing algorithms, identifying stress zones through adaptive threshold segmentation based on contour features, and determining the actual angular position of each fiber core's polarization axis on the end face using concentric circle weighted average positioning technology or sub-pixel edge detection algorithms. The three-dimensional coordinate system is a three-dimensional reference system established based on the spatial geometry of the fiber array, used to quantitatively describe the spatial pose of each fiber core's polarization axis at the exit end face, including angular offsets and rotation trend vectors. The polarization axis is the characteristic direction in the polarization-maintaining fiber that maintains the polarization state of linearly polarized light, i.e., the fast or slow axis direction, corresponding to the direction of the line connecting the centers of two stress zones in the fiber end face image. Angular offset and fiber core rotation trend vector: Angular offset is the deviation of each fiber core's polarization axis from the target angle at the exit end face; rotation trend vector characterizes the direction and amplitude of torsion of each fiber core along the fiber longitudinal direction due to stress release or thermal effects, used to predict angular drift behavior during curing. The actual spatial pose of the polarization axis is the spatial state data comprehensively describing the angular offset and rotation trend vector of each fiber core's polarization axis at the exit end face in a three-dimensional coordinate system. Curing shrinkage stress and thermal mismatch slip are the tangential torque generated by volume shrinkage during UV adhesive curing (typically 2-5%), and the submicron-level relative slippage caused by the mismatch in thermal expansion coefficients between the ferrule, ceramic, or glass and the optical fiber during baking and thermosetting. Both constitute the main physical causes of polarization axis angular drift. Angular preset is the reverse angular compensation value applied in advance during fiber core alignment to counteract the angular drift caused by curing shrinkage stress and thermal mismatch slip. Fiber array alignment is the assembly process of inserting each fiber core into the V-groove substrate at a predetermined polarization axis angle and completing the initial positioning.The polarization axis angular pre-bias angle is the initial angular position assigned to each fiber core before curing triggering. This angle drifts precisely to the target polarization axis alignment angle after curing shrinkage stress and thermal mismatch sliding. The multi-temperature zone stepped curing process uses a curing curve with multiple temperature zones progressively increasing. By controlling the curing rate in segments, shrinkage stress and thermal mismatch stress are released step by step, suppressing the cumulative angular drift of the polarization axis. The target polarization axis alignment posture is the spatial angular state of the polarization axis achieved by each fiber core after angular pre-torsion before curing triggering, ensuring that the polarization axis is precisely at the designed target angle after curing. Curing and shaping involves UV curing or thermal curing to completely cure the adhesive, fixing each fiber core and the V-groove substrate together to form the final fiber array assembly. The fiber core polarization axis angular drift is the angular deviation between the actual angular position of each fiber core's polarization axis after curing and shaping and the target polarization axis alignment posture before curing. After processing, polarization-maintaining fiber array assemblies with a polarization-maintaining angle of ±0.3° or less, and with the angular drift of each fiber core controlled within ±0.3°, achieve an extinction ratio that meets the requirements for high-precision applications. Using ±0.3° as the control target for polarization axis angular drift aligns with industry-standard technical requirements and represents a high-precision level. The polishing end face angle of polarization-maintaining fiber arrays is generally required to be controlled within ±0.3°. Product specifications from several major manufacturers specify a polishing angle tolerance of ±0.3°. Manufacturing technical documents for multi-core polarization-maintaining components also clearly state that the polishing angle of each fiber must be controlled within ±0.3° to minimize insertion loss and maintain polarization performance; this serves as an important reference for the rationality of the polarization axis angular drift control target. The polarization axis alignment error of polarization-maintaining fiber assemblies is typically required to be controlled within ±1° to prevent polarization crosstalk. The end-face imaging inspection method can achieve a theoretical alignment accuracy better than 0.3°; the ±0.3° angular drift control target is on the same order of magnitude as the alignment accuracy requirement, and is technically consistent. The polarization axis angular deviation is directly related to the extinction ratio; engineering data shows that when the slow axis angular deviation is within 3°, the system coupling extinction ratio can reach over 25dB; the more stringent ±0.3° angular drift control can provide more sufficient process margin for such high extinction ratio requirements; some products have already achieved an extinction ratio ≥25dB ​​as a technical standard. ±0.3° as the control target for the polarization axis angular drift after curing not only meets industry-standard accuracy but also matches the requirements for polarization axis alignment accuracy and extinction ratio performance.

[0018] In the above embodiments, the technical feature of acquiring initial polarization axis azimuth data provides a reference for polarization axis alignment, ensuring that the calibration operation is based on accurate initial angular distribution measurements. By quantifying the angular deviation of each fiber core's fast or slow axis relative to the array reference surface, a data foundation is laid for polarization axis tracing. The technical feature of polarization axis tracing calibration achieves three-dimensional reconstruction of the spatial pose of the polarization axis at the exit end face through image processing algorithms; it can accurately describe the angular offset and rotation trend vector, solving the deficiency of traditional methods in quantifying the dynamic rotation of the fiber core, and providing high-precision input parameters for pre-torsion compensation. The technical feature of generating an independent pre-torsion compensation parameter set performs mechanical modeling and reverse compensation for curing shrinkage stress and thermal mismatch slippage; by using angular presets, it achieves accurate prediction of the differentiated deformation of different fiber cores, and combined with the sequentially executed angular pre-torsion operations, the target polarization axis alignment posture completes the pre-compensation of thermomechanical stress before curing. The multi-temperature zone stepped curing process is characterized by suppressing the accumulation of non-uniform stress during the curing process through a controllable gradient temperature field. In synergy with the pre-torsion compensation parameters, the final polarization axis angular drift is controlled within ±0.3°, meeting the stringent requirements of polarization-maintaining fiber array components for polarization retention performance.

[0019] In summary, this embodiment achieves polarization axis stability control of the fiber array from the free state to the solidified state through the closed-loop coordination of four technical modules: initial data acquisition, three-dimensional pose calibration, dynamic pre-compensation, and gradient solidification. This solves the technical problem of polarization axis misalignment caused by solidification stress in traditional assembly methods.

[0020] Example 2: Based on Example 1, the process of using an image processing algorithm to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array in step S200 of this embodiment of the invention specifically includes the following steps: Step S201: Acquire image data of the output end face of the polarization-maintaining fiber array; Among them, the image data of the output end face includes the morphological features of the stress zone of each fiber core end face and the spatial distribution information of the reference marks on the array substrate; Step S202: Use the contour segmentation algorithm based on adaptive threshold to extract the stress zone boundary of the exit end face image data, and use the concentric circle weighted average positioning algorithm to calculate the center coordinates of the two stress zones of each fiber core. Determine the instantaneous angular orientation of the fiber core polarization axis at the exit end face based on the direction of the line connecting the centers of the two stress zones of the same fiber core. Step S203: Based on the instantaneous angular orientation of each fiber core, combined with the angle reference of the array reference surface in the three-dimensional coordinate system and the obtained initial polarization axis azimuth angle data of the incident end face, calculate the angular offset of each fiber core at the exit end face; and determine the rotation trend vector of each fiber core along the longitudinal direction of the fiber by longitudinal correlation analysis of the difference in polarization axis angular orientation between the incident end and the exit end of the same fiber core; and combine the angular offset and the rotation trend vector to form the actual spatial pose of the polarization axis of each fiber core at the exit end face.

[0021] Among them, the stress zone morphology features are the geometric contours, grayscale distributions, and relative position information of the two symmetrical stress regions generated by the doped region in the polarization-maintaining fiber end-face image, serving as the underlying visual basis for polarization axis direction identification; the spatial distribution information of the array substrate reference marks is the position and angle data of the preset positioning marks or reference edges on the V-groove substrate end face in the image coordinate system, used to establish the mapping relationship between the output end-face image and the three-dimensional coordinate system. Instantaneous angular orientation is the instantaneous angle of the fiber core polarization axis in the current physical state, determined by identifying the direction of the line connecting the centers of the two stress zones of the same fiber core in the output end-face image, including the absolute angular position of the fast axis or slow axis relative to the horizontal axis of the image, serving as a direct input parameter for calculating the angular offset. The array reference surface in the three-dimensional coordinate system is a reference surface in the three-dimensional rectangular coordinate system established based on the spatial geometry of the fiber array. The reference surface is determined by the normal and orientation of the physical reference plane of the V-groove substrate in three-dimensional space, used to unify the measurement benchmark of the polarization axis angle between the incident end face and the output end face, making the angular data of the two end faces comparable. The angular reference is the standard zero-position angle value corresponding to the normal or preset marked direction of the array reference reference plane in a three-dimensional coordinate system. It serves as the absolute reference zero point for calculating the angular offset of each fiber core's polarization axis at the exit end face. The angular offset is the angular deviation between the actual instantaneous angular orientation of each fiber core's polarization axis at the exit end face and the angular reference. It is used to quantify the degree of static angular deviation of each fiber core's polarization axis before curing due to processing errors, assembly stress, and other factors, providing a basis for pre-torsion compensation. The polarization axis angular difference is the difference between the initial polarization axis azimuth angle of the same fiber core at the incident end face and its instantaneous angular orientation at the exit end face. This difference reflects the degree of angular inconsistency between the polarization axes at both ends of the fiber due to residual torsion within the fiber, geometric bending, or accumulated torsion during the manufacturing process. Longitudinal correlation analysis compares and calculates the difference quotient of the polarization axis angular data at the incident and exit end faces along the fiber length of the same fiber core to evaluate the rate of change of the polarization axis along the fiber's longitudinal direction, used to separate static installation errors from dynamic torsion trends. The rotation trend vector is a vector parameter determined based on the longitudinal correlation analysis results. It characterizes the torsional direction and angular drift amplitude of each fiber core along its longitudinal direction due to stress release, thermal effects, or adhesive shrinkage. It is used to predict the angular drift behavior of the polarization axis during the curing process and serves as one of the inputs to the independent pre-torsion compensation parameter set.

[0022] In the above embodiments, this embodiment first addresses the acquisition and processing of fiber end-face image data. It achieves sub-pixel-level recognition accuracy of the polarization-maintaining fiber stress zone morphology through a high-precision stress zone boundary extraction algorithm and a concentric circle weighted positioning method. This effectively overcomes the sensitivity of traditional threshold segmentation to uneven illumination, ensuring accurate extraction of the center coordinates of the dual stress zones even against complex image backgrounds. Furthermore, it establishes a mapping relationship between the end-face image and the three-dimensional assembly coordinate system by combining the spatial distribution data of the substrate reference marks, providing a basis for coordinate system transformation to calculate the polarization axis spatial pose. Secondly, in the polarization axis angular parameter calculation module, the instantaneous angular orientation data of each fiber core's polarization axis is obtained through the direction analysis technique of the connection between the centers of the dual stress zones. As the core element of the polarization axis spatial pose, the calculation accuracy of these parameters directly determines the effectiveness of subsequent offset compensation. A unified measurement system is established using the angle reference of the three-dimensional reference surface, ensuring that the polarization axis azimuth data of the incident and exit ends have the same measurement origin, eliminating system errors introduced by coordinate system differences. Further, a longitudinal correlation analysis algorithm was used to quantitatively analyze the angular difference of the polarization axes at both ends, effectively distinguishing between static assembly errors and dynamic torsional effects. Based on the fiber longitudinal torsional mechanical model, the instantaneous positional deviation generated during assembly was decoupled from the torsional trend caused by the inherent stress of the material. The obtained rotational trend vector accurately characterizes the possible angular drift of the polarization axes during fiber curing. The final output set of actual spatial pose parameters for the polarization axes includes two key parameters: angular offset and rotational trend vector. The former accurately reflects the static deviation of each fiber core's polarization axis relative to its theoretical position under the current assembly state, while the latter predicts the possible dynamic rotational behavior of the polarization axes during curing. The combination of these two types of parameters provides a complete spatial pose correction basis for pre-torsional compensation, ensuring that the polarization axis alignment accuracy of the fiber array after curing meets the polarization-maintaining transmission requirements. This embodiment realizes the parameter conversion from two-dimensional image features to three-dimensional spatial pose, providing a quantifiable process control standard for the precise assembly and adjustment of polarization-maintaining fiber arrays.

[0023] Example 3: Based on Example 2, the process of determining the instantaneous angular orientation of the fiber core polarization axis at the exit end face according to the direction of the line connecting the centers of the two stress regions of the same fiber core in step S202 of this embodiment of the invention specifically includes the following steps: Step S2021: Obtain the image data of the exit end face, use the contour segmentation algorithm based on adaptive threshold to extract the stress zone boundary of the exit end face image data, determine the boundary contour information of the two stress zones in each fiber core end face; and use the concentric circle weighted average positioning algorithm to perform sub-pixel level center fitting on the boundary contour information, and calculate the center coordinates of the two stress zones of each fiber core. Step S2022: Based on the center coordinates of the two stress zones of the same fiber core, determine the direction of the line connecting the centers of the two stress zones as the instantaneous angular orientation of the fiber core polarization axis at the exit end face. The instantaneous angular orientation includes the absolute angular position of the fast axis or slow axis relative to the horizontal axis of the image.

[0024] In this context, the stress zone boundary is the geometric boundary line formed by the abrupt grayscale change between the doped stress zone around the fiber core and the cladding region in the polarization-maintaining fiber end-face image. The boundary shape is approximately circular or elliptical, serving as the input contour for the stress zone center localization algorithm. Its extraction accuracy directly affects the accuracy of the polarization axis angle value. The boundary contour information is a sequence of boundary pixel coordinates of each stress zone's connected regions extracted by the contour tracking algorithm after adaptive thresholding and morphological filtering. It includes the two-dimensional coordinates of each boundary point and their spatial arrangement order, used as input to the concentric circle weighted average localization algorithm to calculate the stress zone center coordinates. It serves as the intermediate data carrier connecting image segmentation and center fitting. Sub-pixel-level center fitting, based on pixel-level boundary contour extraction, uses the concentric circle weighted average localization algorithm to perform weighted iterative calculations on the boundary pixels. This allows the calculation accuracy of the stress zone center coordinates to break through the discrete resolution limitation of a single pixel, achieving a localization accuracy of 0.1 pixels or better, providing high-precision spatial position input for polarization axis angle calculation. Instantaneous angular orientation is the instantaneous angular position of the fiber core polarization axis under the current physical state, determined by the direction of the line connecting the centers of the two stress zones of the same fiber core at the moment of image acquisition at the output end face. The orientation comprehensively reflects the inherent birefringence axis direction of the optical fiber, the elastic torsion generated during assembly, and the static deflection caused by residual stress, serving as the direct fundamental parameter for calculating angular offset and rotation trend vector. The absolute angular position of the horizontal axis of the image is a preset horizontal reference direction in the output end face image, i.e., the positive X-axis direction in the image coordinate system, serving as the absolute zero-degree reference for measuring the angular orientation of each fiber core polarization axis. A mapping relationship is established between the absolute angular position and the angular reference surface of the array in the three-dimensional coordinate system through camera calibration parameters, realizing the angular position conversion from the image domain to the spatial domain, so that the polarization axis data of both ends have a unified measurement origin.

[0025] For example, using an adaptive threshold segmentation technique based on contour features to improve the speed and robustness of stress zone identification specifically includes the following steps: Obtain the grayscale processing result of the outgoing end face image data, and establish the grayscale distribution matrix of the whole image based on the grayscale value of each pixel; The gray-level distribution matrix is ​​divided into multiple local windows. For each local window, the adaptive segmentation threshold of the window is independently calculated based on the statistical distribution characteristics of the pixel gray-level values ​​within the window, including the mean, standard deviation, and peak distribution of the gray-level histogram. The adaptive segmentation threshold satisfies the following: when the gray-level contrast between the target area and the background area within the window is lower than the preset lower limit, dynamic compensation is performed by adjusting the threshold coefficient. Binarization is performed on pixels within each local window using an adaptive segmentation threshold. Pixels with grayscale values ​​greater than or equal to the threshold are marked as target pixels, and pixels with grayscale values ​​less than the threshold are marked as background pixels. The binarization results of all local windows are merged to generate the full target pixel. Figure 2 Value-enhanced image; For the whole Figure 2 The binarized image undergoes morphological opening and closing operations to eliminate isolated noise points and fill in tiny holes inside the target region, resulting in a filtered binarized image. A contour tracking algorithm is performed on the filtered binarized image to extract the boundary pixel chains of each connected region, forming the boundary contour information of each stress zone. For each boundary contour, based on its geometric feature parameters, including contour area, roundness, aspect ratio, and contour convexity, pseudo contours that do not conform to the geometric features of the stress zone are eliminated, and the true boundary contours of the two stress zones in each fiber core end face are retained.

[0026] For example, using concentric circle weighted average positioning technology to improve the positioning accuracy of stress zones specifically includes the following steps: Obtain the set of coordinates of all boundary pixels on the defined boundary contour of each stress zone, denoted as ,in The total number of pixels on the boundary contour; Calculate the geometric centroid coordinates of the boundary pixel set as the initial center estimate. ,satisfy: With initial center estimate Using the center of the circle as the boundary, calculate the Euclidean distance from each boundary pixel to the center of the circle: Then, statistically analyze the distribution of all distance values ​​to determine the radius value corresponding to the mode or median distance. As an initial radius estimate; Build with Center of the circle Using a concentric reference circle with radius , the set of boundary pixels is divided into inner and outer zones, where the inner zone pixels satisfy the following condition: The outer pixel count meets , This is a preset bandwidth threshold; Assign a first weight coefficient to the inner-band pixels Assign a second weighting coefficient to outer-band pixels ,and > To suppress the interference of out-of-band noise points on center localization; calculate the weighted center coordinate estimate: in, ; To obtain Using the updated center, iterative optimization is repeated until the center coordinate offset between two consecutive iterations is less than the preset convergence accuracy threshold. The coordinates of the center of the circle at the time of convergence are output as the final center coordinates of the stress zone.

[0027] Through the above steps, the final center coordinates of the two stress zones in each fiber core end face are calculated respectively, which serve as input data for determining the instantaneous angular orientation of the polarization axis.

[0028] In the above embodiments, this embodiment achieves highly robust identification of stress zone boundaries through adaptive threshold segmentation and contour extraction. Based on the concentric circle weighted average positioning algorithm, it overcomes pixel resolution limitations to obtain sub-pixel level stress zone center coordinates. Finally, it accurately calculates the instantaneous angular orientation of the polarization axis through the direction of the connection between the centers of the two stress zones. During fiber array assembly and adjustment, the adaptive threshold segmentation technology effectively overcomes non-uniform noise such as uneven illumination and dirt interference in the end-face image, ensuring the stability of stress zone contour extraction. Morphological filtering and contour screening eliminate pseudo-contour interference such as bubbles and scratches, accurately locking the true dual stress zone boundaries around the fiber core. The inner-band weighting mechanism of the concentric circle weighted positioning algorithm suppresses the influence of boundary burrs and outliers. Through iterative optimization, the accuracy of center coordinate calculation is improved to the sub-pixel level, providing a reliable spatial reference for polarization axis angular orientation calculation. When determining the instantaneous polarization axis orientation through the connection between the centers of the two stress zones, this technology can simultaneously reflect the inherent birefringence axis of the fiber and the elastic deformation effect caused by assembly. The horizontal axis of the image serves as the absolute angular reference, and combined with camera calibration parameters, spatial mapping between the image coordinate system and the assembly reference plane is achieved, ensuring the comparability of measurement results for multi-core polarization axis alignment deviations under a unified coordinate system. Sub-pixel-level center positioning controls the polarization axis angular measurement error to within 0.1°, meeting the accuracy requirements for maintaining polarization consistency in high-density fiber arrays. The closed-loop data processing flow formed by the entire technology chain provides quantitative basis for assembly operations such as rotational alignment and stress compensation of polarization-maintaining fiber arrays.

[0029] This embodiment directly serves three key aspects of polarization axis alignment and adjustment: first, it rapidly calibrates the initial angular distribution of the polarization axes of each fiber core in the array using end-face images; second, it monitors the dynamic deflection of the polarization axes caused by mechanical stress during assembly; and third, it provides high-precision feedback data for micro-rotation adjustments. Ultimately, it achieves precise alignment of the fast and slow axes of the polarization-maintaining fibers in the fiber array with the system reference axis, ensuring the stability of optical path polarization state transmission.

[0030] Example 4: Based on Example 1, the process of determining the target polarization axis alignment attitude of each fiber core before curing in step S300 of this embodiment of the invention specifically includes the following steps: Step S301: Obtain the actual spatial pose of the polarization axis of each fiber core at the exit end face. Based on the angular offset and rotation trend vector in the actual spatial pose of each polarization axis, and combined with the reverse compensation algorithm of curing shrinkage stress and thermal mismatch slippage, calculate the angular preset amount corresponding to each fiber core. Generate an independent pre-torsion compensation parameter set for each angular preset amount according to the fiber core number index. Step S302: Using an independent pre-torsion compensation parameter set, during the fiber array axis assembly process, extract the corresponding angular preset amount for each fiber core one by one, and apply a reverse angular rotation operation to the fiber core according to the angular preset amount, so that the polarization axis of the fiber core deflects from the current angular position to the pre-torsion angle. Step S303: After all fiber cores have completed the reverse angular rotation operation, the pre-twist angle of the polarization axis of each fiber core is recorded as the polarization axis angular pre-bias angle of the fiber core before curing trigger. The angular pre-bias angles of each polarization axis together constitute the target polarization axis alignment posture of each fiber core before curing.

[0031] The reverse angular rotation operation refers to the process in the fiber array axis assembly process where, based on the angular preset values ​​corresponding to each fiber core in the independent pre-torsion compensation parameter set generated in step S301, a precision rotating fixture is used to apply active angular deflection to the target fiber core. Using the currently measured angular position of the polarization axis of each fiber core as the starting reference, the polarization axis of the fiber core is deflected from its current angular position in the opposite direction to the curing drift by an angle equal to the angular preset value, thereby bringing the fiber core's polarization axis to the pre-torsion angle. The reverse angular rotation operation is performed independently for each fiber core, and its deflection direction and amplitude are uniquely determined by the angular preset value corresponding to the fiber core. The angular preset values ​​between different fiber cores are independent and uncoupled. The angular preset value is converted from the calculation parameter into the physical attitude. Before the curing trigger, the polarization axis of the fiber core is artificially preset to a position deviating from the target angle. The magnitude and direction of the deviation are equal to and opposite to the expected angular drift caused by shrinkage stress and thermal mismatch during the curing process, so that the actual polarization axis after curing falls exactly at the design target angle. Through operation, the polarization axis of each fiber core changes from the instantaneous angular orientation of the exit end face determined in step S203 to the polarization axis angular pre-bias angle recorded in step S303, completing the state transformation from the measured pose to the pre-compensated pose, and providing the initial attitude input for the multi-temperature zone stepped curing in step S400.

[0032] In the above embodiments, this embodiment optimizes the polarization axis alignment accuracy of the polarization-maintaining fiber array through a pre-torsion compensation mechanism to ensure that the polarization axis pose after curing meets the target alignment requirements. The preset amount calculation module in step S301, based on the measured angular offset and rotation trend vector of the polarization axis pose, combined with the curing shrinkage stress and thermal mismatch slip prediction model, generates customized compensation parameters for different fiber cores. The algorithm quantifies the stress-induced deflection effect during the curing process and maps the reverse compensation angle to an independent pre-torsion parameter set, providing a reference input for subsequent fiber core-by-fiber adjustment. The execution unit in step S302 achieves differentiated control through the independent pre-torsion compensation parameter set, applying an angular pre-deflection operation opposite to the curing deformation direction to each fiber core. This operation actively adjusts the polarization axis from the real-time measured pose to the pre-calculated theoretical anti-deformation pose, offsetting the non-uniform stress influence caused by resin shrinkage or differences in thermal expansion coefficients during the subsequent curing stage. The pre-bias state recording module in step S303 establishes the final spatial angular distribution of polarization axes before curing. This distribution is the key intermediate state for achieving target alignment after curing. The pre-bias angle set ensures that the actual polarization axis pose of all fiber cores converges to the design tolerance range after the curing stress is released, thus eliminating polarization crosstalk between fiber cores in the array.

[0033] In summary, this embodiment improves the polarization axis stability of the fiber array during the curing process: First, the compensation algorithm based on the physical model matches the pre-torsion amount with the actual curing deformation, avoiding systematic errors caused by empirical compensation; second, the independent parameter set supports differentiated processing of heterogeneous fiber cores in the array, adapting to asymmetric deformations caused by different coating materials or curing conditions; finally, the pre-bias angle set serves as the input condition for the curing process, ensuring the overall polarization axis consistency of the array meets the polarization maintenance requirements of multi-core photonic integrated devices.

[0034] Example 5: Based on Example 4, the process of calculating the angular preset amount corresponding to each fiber core in step S301 of this embodiment of the invention specifically includes the following steps: Step S3011: Obtain the actual spatial pose data of the polarization axis of each fiber core at the output end face and the curing process parameter set; wherein, the curing process parameter set includes the UV adhesive curing shrinkage rate, the thermal curing temperature range, the thermal expansion coefficient of the ferrule material and the thermal expansion coefficient of the optical fiber material. Step S3012: For each fiber core, based on the rotation trend vector in the actual spatial pose of the polarization axis, combined with the UV adhesive curing shrinkage rate and the thermosetting temperature range, calculate the predicted value of the first angular drift of the fiber core under the action of curing shrinkage stress. Step S3013: Based on the predicted value of the first angular drift of the same fiber core, and combined with the difference between the thermal expansion coefficient of the ferrule material and the thermal expansion coefficient of the optical fiber material, calculate the predicted value of the second angular drift of the fiber core under thermal mismatch sliding. Step S3014: Superimpose the first angular drift prediction value and the second angular drift prediction value of each fiber core to obtain the total expected angular drift of each fiber core during the curing process; take the opposite direction of the total expected angular drift as the compensation direction and the absolute value of the total expected angular drift as the compensation amplitude to determine the angular preset amount of each fiber core, so that the angular preset amount and the total expected angular drift satisfy the vector cancellation relationship.

[0035] Among them, the UV-curable adhesive curing shrinkage rate refers to the percentage of volume shrinkage that occurs when the UV-curable adhesive changes from a liquid to a solid state during the photo-initiated polymerization reaction, typically ranging from 2% to 5%. The shrinkage rate directly determines the amplitude of the tangential shrinkage stress acting on the surface of each fiber core during curing, and is a fundamental material parameter for calculating the predicted value of the first angular drift. Differences in the amount of adhesive applied to different fiber cores may lead to local fluctuations in the actual shrinkage rate. The thermosetting temperature range refers to the temperature range from the initial temperature to the final temperature set in the baking thermosetting process. The temperature change within this range determines the cumulative amount of thermal mismatch strain between the ferrule and the optical fiber due to the difference in their coefficients of thermal expansion, and is a key process parameter for calculating the predicted value of the second angular drift under thermal mismatch sliding. The coefficient of thermal expansion of the ferrule material refers to the linear expansion rate of the V-groove substrate or ceramic ferrule material, such as zirconia ceramic or glass, under a unit temperature change; the coefficient of thermal expansion of the optical fiber material refers to the linear expansion rate of the polarization-maintaining fiber cladding or coating material under a unit temperature change. The difference between the two is the fundamental physical reason for the thermal mismatch slippage. The larger the difference, the greater the relative sliding displacement between the ferrule and the optical fiber during the thermosetting heating process, resulting in a more significant angular drift of the polarization axis. The predicted value of the first angular drift refers to the expected angular deflection angle of each fiber core polarization axis driven by the tangential shrinkage torque when only considering the effect of UV adhesive curing shrinkage stress. The predicted value is obtained by substituting the rotation trend vector and the UV adhesive curing shrinkage rate into the curing shrinkage stress model, reflecting the independent contribution of the curing shrinkage effect to the angular misalignment of the polarization axis. Thermal mismatch sliding refers to the difference in expansion displacement between the ferrule and optical fiber materials during thermosetting heating due to the mismatch in their thermal expansion coefficients. This difference manifests as submicron-level relative sliding, transmitted to the fiber core surface via friction or adhesion, generating additional torsional torque and driving an additional angular drift of the polarization axis. This effect is the physical source of the second angular drift prediction. The second angular drift prediction is the additional angular deflection prediction resulting from the superposition of thermal mismatch sliding on the first angular drift prediction. This prediction is calculated based on the difference in thermal expansion coefficients between the ferrule and optical fiber materials and the thermosetting temperature range, reflecting the independent contribution of the thermal mismatch sliding effect to the polarization axis angular misalignment. The total expected angular drift refers to the comprehensive angular drift prediction obtained by vector superimposing the first and second angular drift prediction values ​​of the same fiber core. It characterizes the total angular deflection and deflection direction that may occur from the pre-curing attitude to the post-curing attitude of the fiber core polarization axis under the combined action of UV curing shrinkage stress and thermal mismatch sliding.The compensation direction refers to the vector direction opposite to the direction of the total expected angular drift. In step S3014, the angular preset amount is oriented with this opposite direction as the orientation reference, so that the vector direction of the preset amount is 180° different from the vector direction of the total expected angular drift. By setting the compensation direction, it is ensured that the pre-twisting operation makes the direction of the fiber core polarization axis deviating from the target angle in advance exactly opposite to the subsequent curing drift direction, so that the actual polarization axis after curing automatically converges to the design target angle.

[0036] In the above embodiments, this embodiment establishes a quantitative correlation model between process parameters and physical deformation by acquiring the actual spatial pose data of the polarization axis and the curing process parameter set; the polarization axis rotation trend vector provides an initial direction prediction benchmark for the angular displacement caused by curing stress; the UV adhesive curing shrinkage rate parameter transforms the volume change of the colloidal phase transition process into a quantitative input of stress load; and the thermosetting temperature range parameter defines the boundary conditions of the material creep response; both together support the calculation accuracy of the first angular drift prediction value. The introduction of the difference in thermal expansion coefficients between the ferrule and optical fiber materials accurately characterizes the displacement coupling effect of heterogeneous materials in the temperature field; the parameter difference is converted into a driving factor for thermal mismatch sliding displacement through the thermodynamic constitutive equation, enabling the second angular drift prediction value to reflect the multi-physics coupling behavior under real working conditions; the linear superposition of the first and second prediction values ​​establishes a complete mathematical model of the total expected angular drift. The angular preset value is designed using the principle of vector cancellation, so that the systematic error introduced by the curing process is reverse-compensated during the assembly and adjustment stage; this ensures that after the fiber array undergoes curing shrinkage and thermal cycling, the deviation of the actual azimuth angle of each fiber core polarization axis from the design value converges within the allowable tolerance range; and finally, the polarization crosstalk index stability of the polarization-maintaining fiber array is achieved over a wide temperature range.

[0037] Example 6: As Figure 3 As shown, based on Embodiments 1-5, the assembly and adjustment system for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array provided in this embodiment of the invention includes: The azimuth data acquisition module 1 is used to acquire the initial polarization axis azimuth data of each fiber core in the polarization-maintaining fiber array at the incident end face; wherein, the initial polarization axis azimuth data includes the angular distribution measurement values ​​of the fast axis or slow axis of each fiber core relative to the array reference plane; The spatial pose determination module 2 is used to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array using image processing algorithms based on the initial polarization axis azimuth angle data, and to determine the actual spatial pose of the polarization axis of each fiber core at the output end face; wherein, the actual spatial pose of the polarization axis is used to describe the angular offset of the polarization axis of each fiber core at the output end face and the fiber core rotation trend vector in a three-dimensional coordinate system. The pre-torsion operation module 3 is used to generate an independent pre-torsion compensation parameter set for each fiber core based on the actual spatial pose of multiple polarization axes corresponding to multiple fiber cores. The independent pre-torsion compensation parameter set includes angular preset amounts for reverse compensation of curing shrinkage stress and thermal mismatch slip. Using the independent pre-torsion compensation parameter set, angular pre-torsion operation is performed on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. The target polarization axis alignment posture includes the polarization axis angular pre-bias angle of each fiber core before curing triggering. The curing and shaping module 4 is used to cure and shape the fiber array in the target polarization axis alignment posture using a multi-temperature zone stepped curing process, so as to obtain a polarization-maintaining fiber array component with a polarization axis angular drift of each fiber core less than or equal to ±0.3° after curing.

[0038] In the above embodiments, this embodiment achieves high-precision alignment and stable curing of the polarization axis of the polarization-maintaining fiber array through a modular technical architecture. The azimuth data acquisition module 1 establishes a unified spatial reference for the azimuth angle of the incident polarization axis by measuring the angular distribution values ​​of the reference reference plane, providing an initial angular calibration basis for the assembly and adjustment process; the clear distinction between the fast axis and the slow axis ensures that fiber cores with different polarization characteristics receive targeted processing. The spatial pose determination module 2 describes the actual spatial pose of the polarization axis in a three-dimensional coordinate system, realizing mathematical modeling of the polarization state at the incident and emitting ends; the precise quantification of the angular offset reflects the mechanical assembly error during the assembly and adjustment process, while the rotation trend vector characterizes the influence of the fiber's own torsion characteristics on polarization stability. The pre-torsion operation module 3, with its independent pre-torsion compensation parameter set, actively compensates for curing shrinkage stress and thermal mismatch slippage; the introduction of angular presets offsets the anisotropic deformation during the material curing process, ensuring that the target polarization axis alignment posture reaches the ideal spatial distribution under a thermo-mechanical coupling environment before curing. The multi-temperature zone stepped curing process of the curing and shaping module 4 reduces the residual stress concentration effect through gradient temperature control. The suppression effect of polarization axis angular drift after curing verifies the assembly and adjustment system's ability to accurately control the material phase transformation process. Finally, the component meets the polarization maintenance requirements of a high-stability optical system.

[0039] In summary, the technical chain of this embodiment—establishing the incident end reference, calibrating the output end pose, generating pre-compensation parameters, and gradient curing—systematically solves the polarization axis misalignment problem of polarization-maintaining fiber arrays in mechanical assembly, material curing, and thermal environment adaptation.

[0040] The fiber array in this invention can be a 14-channel high-precision hybrid fiber array; Employing high-precision V-groove glass substrate technology, this product integrates 8 single-mode fibers and 6 polarization-maintaining fibers (3×2 polarization-maintaining fibers + 8×1 single-mode fibers), with SC / APC 8° angle polished connectors at the ends. This enables high-precision multi-channel fiber arrangement, low-loss transmission, and external optical path interfacing. The product strictly adheres to the dimensional tolerances and process requirements specified in the design drawings, making it suitable for high-end optical communication scenarios such as silicon photonics chips, high-speed optical modules, WDM / Demux systems, and polarization-maintaining optical devices.

[0041] As shown in Table 1, the 14-channel hybrid fiber design consists of 8 channels of 9μm core diameter single-mode fiber + 6 channels of 9μm core diameter polarization-maintaining fiber to meet the optical path requirements of multiple scenarios; the high-precision fiber array has a core spacing of 0.3625mm and a maximum center deviation in the height direction of ≤0.0005mm.

[0042] Table 1 Basic Information Figure 4 A block diagram of an exemplary electronic device suitable for implementing embodiments of the present invention is shown.

[0043] The electronic device may include a central processing unit / microprocessor / main control chip 5; and a storage medium 6 coupled to the central processing unit / microprocessor / main control chip 5, wherein computer-executable instructions are stored for performing the steps of various methods of embodiments of the present invention when executed by the processor.

[0044] The central processing unit / microprocessor / main control chip 5 may include, but is not limited to, one or more processors or microprocessors.

[0045] Storage medium 6 may include, but is not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, computer storage media (e.g., hard disk, floppy disk, solid-state drive, removable disk, CD-ROM, DVD-ROM, Blu-ray disc, etc.).

[0046] In addition, the electronic device may include (but is not limited to) a data bus 7, an input / output bus / external bus / device bus 8, a display 9, and input / output devices 10 (e.g., keyboard, mouse, speaker, etc.).

[0047] The central processing unit / microprocessor / main control chip 5 can communicate with external devices (9, 10, etc.) via wired or wireless networks (not shown) through the input / output bus / external bus / device bus 8.

[0048] The storage medium 6 may also store at least one computer-executable instruction for performing the steps of various functions and / or methods in the embodiments described herein when the central processing unit / microprocessor / main control chip 5 is running.

[0049] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0050] Figure 5 A schematic diagram of a computer-readable storage medium according to an embodiment of the present invention is shown.

[0051] like Figure 5 As shown, the non-transitory computer-readable storage medium 12 stores instructions, such as computer-readable instructions 11. When the computer-readable instructions 11 are executed by a processor, the various methods described above can be performed. The non-transitory computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Non-transitory non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, the non-transitory computer-readable storage medium 12 can be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions 11 stored on the non-transitory computer-readable storage medium 12, the various methods described above can be performed.

[0052] In the embodiments provided by this invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for instance, the division of 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 systems or units may be electrical, mechanical, or other forms.

[0053] 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 this embodiment according to actual needs.

[0054] Furthermore, the functional units in the various embodiments of the present invention 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.

[0055] 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, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods of the various embodiments of this invention through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0056] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for aligning the polarization axes of polarization-maintaining fibers in an optical fiber array, characterized in that, Includes the following steps: Obtain the initial polarization axis azimuth angle data of each fiber core in the polarization-maintaining fiber array at the incident end face; For each initial polarization axis azimuth angle data, the polarization axis tracing calibration is performed on the output end face of the polarization-maintaining fiber array to determine the actual spatial pose of each fiber core on the output end face of the polarization axis. Based on the actual spatial pose of multiple polarization axes corresponding to multiple fiber cores, an independent pre-torsion compensation parameter set is generated for each fiber core. Using the independent pre-torsion compensation parameter set, angular pre-torsion operation is performed on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. A multi-temperature zone stepped curing process was used to cure and shape the fiber array in the target polarization axis alignment posture, resulting in a polarization-maintaining fiber array assembly that conforms to the angular drift of each fiber core polarization axis after curing. The process of polarization axis tracing calibration of the output end face of a polarization-maintaining fiber array includes the following steps: Acquire image data of the output end face of the polarization-maintaining fiber array; The stress zone boundary is extracted from the image data of the exit end face, and the coordinates of the center of the two stress zones of each fiber core are calculated. The instantaneous angular orientation of the polarization axis of the fiber core at the exit end face is determined based on the direction of the line connecting the centers of the two stress zones of the same fiber core. Based on the instantaneous angular orientation of each fiber core, combined with the angle reference of the array reference surface in the three-dimensional coordinate system and the obtained initial polarization axis azimuth angle data of the incident end face, the angular offset of each fiber core at the exit end face is calculated. By analyzing the longitudinal correlation between the polarization axis angular differences between the incident and output ends of the same fiber core, the rotation trend vector along the longitudinal direction of the fiber is determined; the angular offset and the rotation trend vector together constitute the actual spatial pose of the polarization axis of each fiber core at the output end face.

2. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, in, The initial polarization axis azimuth data includes the angular distribution measurements of the fast or slow axis of each fiber core relative to the array reference plane.

3. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, in, The actual spatial pose of the polarization axis is used to describe the angular offset of the polarization axis of each fiber core at the exit end face and the fiber core rotation trend vector in a three-dimensional coordinate system.

4. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, Longitudinal correlation analysis calculates the polarization axis angular data at the incident and exit ends of the same fiber core along its fiber length, and evaluates the rate of change of the polarization axis along the longitudinal direction of the fiber. This is used to separate static installation errors from dynamic torsion trends.

5. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, The rotation trend vector is a vector parameter determined based on the longitudinal correlation analysis results. It characterizes the torsional direction and angular drift amplitude of each fiber core along its longitudinal direction due to stress release, thermal effects, or adhesive shrinkage. It is used to predict the angular drift behavior of the polarization axis during the curing process.

6. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, in, The target polarization axis alignment attitude includes the polarization axis angular pre-bias angle of each fiber core before curing trigger.

7. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 1, characterized in that, The process of determining the target polarization axis alignment orientation of each fiber core before curing includes the following steps: Obtain the actual spatial pose of the polarization axis of each fiber core at the exit end face. Based on the angular offset and rotation trend vector in the actual spatial pose of each polarization axis, and combined with the reverse compensation algorithm of curing shrinkage stress and thermal mismatch slippage, calculate the angular preset amount corresponding to each fiber core. Then, generate an independent pre-torsion compensation parameter set for each angular preset amount according to the fiber core number index. Using an independent pre-torsion compensation parameter set, during the fiber array axis assembly process, the angular preset amount corresponding to each fiber core is extracted one by one, and a reverse angular rotation operation is applied to the fiber core according to the angular preset amount, so that the polarization axis of the fiber core is deflected from the current angular position to the pre-torsion angle. After all the fiber cores have completed the reverse angular rotation operation, the pre-twist angle of the polarization axis of each fiber core is recorded as the polarization axis angular pre-bias angle of the fiber core before curing trigger. The angular pre-bias angles of each polarization axis together constitute the target polarization axis alignment posture of each fiber core before curing.

8. The method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in claim 7, characterized in that, In the fiber array axis assembly process, the reverse angular rotation operation is a process of applying active angular deflection to the target fiber core based on the angular preset amount corresponding to each fiber core in the generated independent pre-torsion compensation parameter set. Taking the current measured polarization axis angular position of each fiber core as the starting reference, the fiber core polarization axis is deflected from the current angular position in the opposite direction to the curing drift by an angle value equal to the angular preset amount, so that the fiber core polarization axis reaches the pre-torsion angle.

9. A system for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array, used to implement the method for aligning the polarization axis of a polarization-maintaining fiber in an optical fiber array as described in any one of claims 1 to 8, characterized in that, include: The azimuth data acquisition module is used to acquire the initial polarization axis azimuth data of each fiber core in the polarization-maintaining fiber array at the incident end face; The spatial pose determination module is used to perform polarization axis tracing calibration on the output end face of the polarization-maintaining fiber array using image processing algorithms based on the initial polarization axis azimuth angle data, and to determine the actual spatial pose of each fiber core on the output end face of the polarization axis. The pre-twist operation module is used to generate an independent pre-twist compensation parameter set for each fiber core based on the actual spatial pose of multiple polarization axes corresponding to multiple fiber cores. Using the independent pre-twist compensation parameter set, angular pre-twist operation is performed on each fiber core one by one during the fiber array axis assembly process to determine the target polarization axis alignment posture of each fiber core before curing. The curing and shaping module is used to cure and shape the fiber array in the target polarization axis alignment posture using a multi-temperature zone stepped curing process, so as to obtain a polarization-maintaining fiber array component with a polarization axis angular drift of each fiber core less than or equal to ±0.3° after curing.

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