Cladding optical waveguide parallel preparation method based on femtosecond laser and DOE cooperation

Abstract

The invention relates to the technical field of integrated optical device manufacturing, and discloses a femtosecond laser and DOE cooperation-based cladding optical waveguide parallel preparation method, which comprises the steps of determining an initial parameter preset value of femtosecond laser; outputting femtosecond pulse laser, and performing beam expansion and collimation processing on the femtosecond pulse laser according to the matching degree of the light spot size and the effective aperture size; carrying out space phase modulation on the expanded laser beam by adopting a replaceable optical element to form a two-dimensional multi-focus light spot array; focusing the array into a transparent substrate material to form a high-energy density region; the transparent substrate material is controlled to do uniform linear motion in the preset direction according to the preset processing path, so that the multi-focus light spot array synchronously scans in the transparent substrate material in the preset direction, and a plurality of continuously distributed modification tracks are formed; the multiple modified tracks are distributed on the cross section in a surrounding mode to form a cladding structure, and the cladding optical waveguide structure is obtained. The preparation efficiency of the cladding optical waveguide can be improved.

Description

Technical Field

[0001] This invention relates to the field of integrated optical device manufacturing technology, and more specifically, to a parallel fabrication method for cladding waveguides based on the synergy of femtosecond lasers and DOE. Background Technology

[0002] With the rapid development of integrated optics and optical communication technologies, optical waveguides, as core components in optoelectronic devices, have attracted much attention for their fabrication technology. An optical waveguide is a light transmission structure based on the principle of total internal reflection, possessing characteristics such as high bandwidth, resistance to electromagnetic interference, distributed sensing capabilities, and biocompatibility. It is widely used in fields such as fiber optic communication, lasers, and AR / VR displays. With the popularization of AR devices and the development of 5G, optical waveguide technology is evolving towards lightweighting and high integration. Breakthroughs are continuously being made in technologies such as diffractive waveguides and holographic waveguides, but challenges remain regarding material costs and process complexity. Among numerous fabrication technologies, femtosecond laser direct writing technology, with its ultrashort pulse width and ultra-high peak power, can achieve three-dimensional micro-nano fabrication within materials and is applicable to a wide range of materials (such as crystals, glass, and ceramics), thus becoming an important means of fabricating optical waveguides.

[0003] Especially for certain nonlinear optical crystals or laser crystal materials, a "cladding" waveguide structure is typically used to preserve the original optical properties of the waveguide core. This structure requires the formation of a low-refractive-index damage layer (i.e., cladding) around the waveguide core region through laser irradiation, thereby restricting beam propagation within the core region. However, existing femtosecond laser fabrication techniques for cladding optical waveguides mainly suffer from the following problems: 1. Low processing efficiency: Traditional processing methods typically employ single-focusing, using a point-to-point scanning method to trace the cladding trajectory line by line. Since the cladding structure usually requires dozens or even hundreds of closely spaced scan lines to form a closed optical barrier around the core, this means that processing a single waveguide unit requires extremely long scanning times and repetitive mechanical movements. The processing of a single waveguide often takes tens of minutes or even hours, which is difficult to meet the rapid manufacturing requirements of arrayed devices and greatly limits the ability for industrial mass production.

[0004] 2. High System Stability Requirements: Due to the long single-point scanning time, extremely high requirements are placed on the power stability of the laser and the long-term motion accuracy of the displacement platform. Changes in ambient temperature or mechanical vibrations during long-term processing may lead to uneven waveguide cladding wall thickness or incomplete closure, resulting in increased waveguide transmission loss and light leakage.

[0005] 3. High cost or complex optical path of multi-beam shaping methods: Although there are existing technologies that use spatial light modulators (SLMs) for multi-focus processing, SLM equipment is expensive, has a low damage threshold, and has a complex control system, making it unsuitable for low-cost, high-intensity laser processing environments.

[0006] To address the aforementioned issues, while microlens arrays or beam splitters can be used for beam splitting, these methods often only produce one-dimensional focal points or fixed, simple patterns, making it difficult to flexibly adapt to the complex two-dimensional cross-sectional requirements of cladding waveguides. Diffractive optical elements (DOEs), on the other hand, possess advantages such as small size, high damage threshold, and the ability to customize arbitrary two-dimensional optical field distributions. However, in the efficient fabrication and application of cladding waveguides, specific technical solutions for the collaborative processing of two-dimensional multifocal arrays using DOEs still require further development and optimization.

[0007] Therefore, it is necessary to design a parallel fabrication method for cladding optical waveguides based on femtosecond laser and DOE collaboration to solve the problems existing in the current technology. Summary of the Invention

[0008] In view of this, the present invention proposes a parallel fabrication method for cladding waveguides based on femtosecond laser and DOE synergy. Targeting the application characteristics of cladding waveguide structures in integrated optics, this method combines femtosecond laser micromachining technology with diffractive optical element (DOE) beam shaping technology to solve the technical problems of low processing efficiency, the need for channel-by-channel scanning, poor processing consistency, and difficulty in achieving simultaneous fabrication of multiple channels in the existing femtosecond laser direct-write waveguide process.

[0009] This invention proposes a parallel fabrication method for cladding optical waveguides based on femtosecond laser and DOE collaboration, comprising: Collect specific category data of transparent dielectric materials, extract design parameter data of cladding optical waveguide, obtain calibration parameter data of DOE, and determine the initial parameter preset values ​​of femtosecond laser based on the three types of data; The laser emitting component is activated to output a femtosecond pulse laser according to the preset initial parameter values, and the spot size of the laser beam and the effective aperture size of the laser incident end face are collected. The femtosecond pulse laser is expanded and collimated according to the matching degree of the spot size and the effective aperture size. Replaceable optical elements are used to spatially phase modulate the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multi-focal spot array. The two-dimensional multifocal light spot array is focused onto a predetermined position inside the transparent substrate material by a focusing lens group or a microscope objective, forming a high energy density region inside the transparent substrate material; While being irradiated by a femtosecond pulsed laser, the transparent substrate material is controlled to move at a constant speed in a linear motion along a preset direction according to a preset processing path, so that the multi-focus laser array scans synchronously in the interior of the transparent substrate material along the preset direction, forming multiple continuously distributed modification trajectories. Collect cross-sectional coordinate data of the multiple modified trajectories, and determine whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data; If so, continue to maintain the current motion speed of the transparent substrate material and the output parameters of the femtosecond laser. When multiple modified trajectories are distributed around the cross section to form a cladding structure, stop scanning to obtain the final multiple cladding optical waveguide structures. If not, adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop conditions.

[0010] Furthermore, the parameters of the femtosecond laser include pulse width, repetition frequency, single pulse energy, and average power; The specific category data of the transparent medium material includes data on light transmission properties and structural density; The design parameters of the cladding waveguide include the number of cladding layers and the cross-sectional shape of the light guide core. The calibration parameters of the DOE include the number of focal points, spatial arrangement, effective aperture size, phase modulation accuracy, and focal point energy distribution ratio. The process of determining the initial parameter preset values ​​for the femtosecond laser based on three types of data includes: The three types of data are correlated and matched, and the initial preset values ​​of the femtosecond laser parameters are determined through the data correspondence. When the product of single pulse energy and repetition frequency is greater than the preset value of average power, either single pulse energy or repetition frequency is reduced so that the product equals the preset value of average power. When the product of the single pulse energy and the repetition frequency is less than the preset value of the average power, either the single pulse energy or the repetition frequency is increased so that the product equals the preset value of the average power.

[0011] Furthermore, the laser emission unit outputs a femtosecond pulse laser according to the preset initial parameter value, and acquires the spot size of the laser beam, including: Set fixed acquisition points along the laser output path; The laser beam's major and minor axis lengths are collected using a spot detection component, and the time interval between the collection moment and the laser start-up moment is recorded. When the ratio of the acquired laser major axis length to the minor axis length is greater than the preset ratio, the position of the laser emission port is adjusted, and the spot size is acquired again. When the ratio of the major axis length to the minor axis length is less than or equal to the preset ratio, the spot size data is stored directly.

[0012] Furthermore, the effective aperture size of the laser incident end face includes: The length and width data of the effective aperture of the laser inlet are collected using a dimensional measuring component, and the equivalent diameter of the effective aperture is calculated. Calculate the ratio of the equivalent diameter of the light spot size to the equivalent diameter of the effective aperture to determine the degree of matching between the two; When the ratio is less than the lower limit of the preset matching degree range, the beam expansion ratio is increased to increase the output spot size. When this ratio is greater than the upper limit of the preset matching degree range, the beam expansion ratio is reduced to decrease the output spot size; During the beam expansion process, the collimation component is activated simultaneously to correct the propagation direction of the laser beam, so that the beam propagation direction is perpendicular to the incident end face of the subsequent optical element.

[0013] Furthermore, the method of using replaceable optical elements to spatially phase modulate the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multifocal beam array, includes: The replaceable optical element is fixed in the preset position of the optical path by a detachable connection, ensuring that the phase modulation area of ​​the optical element is aligned with the transmission center line of the laser beam, so that the expanded laser beam is perpendicularly incident on the phase modulation area of ​​the optical element. The laser beam is segmented by the phase distribution of optical elements; Specifically, based on the cross-sectional shape of the light-guiding core in the design requirements of the cladding waveguide, the optical elements are controlled to decompose the laser beam into sub-beam focal points arranged in corresponding shapes, forming a two-dimensional multi-focal spot array of corresponding shapes.

[0014] Furthermore, the step of focusing the two-dimensional multifocal light spot array onto a predetermined position inside the transparent substrate material via a focusing lens group or microscope objective, thereby forming a high energy density region inside the transparent substrate material, includes: Install the focusing lens group or microscope objective on the transmission path of the two-dimensional multifocal spot array, and adjust the distance between the focusing element and the optical element to a preset distance; The surface coordinates of the transparent substrate material are collected by the position detection component, and the axial movement distance of the focusing element to the target position is calculated by combining the preset focusing depth. When half the thickness of the transparent substrate material is less than the preset focusing depth, the placement angle of the transparent substrate material is adjusted first, and then the focusing element is driven to move along the axis to the target position. When half the thickness of the transparent substrate material is greater than or equal to the preset focusing depth, the focusing element is directly driven to move axially to the target position. After the focusing element moves to the target position, it focuses the two-dimensional multi-focus beam array to a preset position inside the transparent substrate material, and each sub-beam focal point forms an independent high-energy-density region inside the material.

[0015] Furthermore, the step of collecting cross-sectional coordinate data of the multiple modified trajectories and determining whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data includes: During the scanning process, the cross-sectional coordinate data of multiple modified trajectories are collected at preset fixed intervals by the cross-sectional detection component; When the cross-sectional coordinates of the modified trajectory satisfy the preset closed loop condition, it is determined that the multiple modified trajectories are distributed in a loop on the cross-section. If the cross-sectional coordinates of multiple modified trajectories do not meet the preset closed loop condition, it is determined that the multiple modified trajectories are not distributed around the cross-section.

[0016] Furthermore, the determination that the preset closed loop condition is met includes: The cross-sectional coordinate data of each modified trajectory collected are sorted sequentially according to the circumferential direction to form the actual trajectory coordinate sequence; When the following four requirements are met: the distance between the first and last coordinate points in the actual trajectory coordinate sequence is less than the preset overlap threshold, the spacing between two adjacent modified trajectories is within the preset spacing range, there are no gaps in any modified trajectories, and the surrounding area formed by multiple modified trajectories surrounds the cross-sectional area of ​​the preset light guide core, then the preset closed surrounding condition is satisfied. If any one of the four requirements is not met, the preset closed loop condition is deemed not to be met.

[0017] Furthermore, the parallel fabrication method for cladding optical waveguides based on femtosecond laser and DOE synergy is characterized in that the determination of satisfying the preset closed-loop condition further includes: Retrieve a preset cladding structure closed path coordinate sequence, calculate the straight-line distance between each position point in the actual trajectory coordinate sequence and the corresponding position point in the preset closed path coordinate sequence, and obtain all the calculated straight-line distances as a distance dataset; Determine whether there is a gap in the modified trajectory based on the distance dataset and the preset distance deviation threshold; If at least one distance value in the distance dataset is greater than a preset deviation distance threshold, it is determined that there is a gap in the modified trajectory. When all distance values ​​in the distance dataset are less than or equal to a preset deviation threshold, it is determined that there is no gap in the modified trajectory.

[0018] Furthermore, adjusting the motion speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop condition includes: Retrieve the cross-sectional coordinate data, distance dataset, spacing, and gap determination results of the modified trajectory that does not meet the preset closed loop conditions, and analyze to determine the specific type of failure to meet the preset closed loop conditions; Adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser according to the type of failure to meet the preset closed surround condition; After each adjustment, the cross-sectional coordinate data of the modified trajectory are re-acquired, and it is determined again whether all preset closed loop conditions are met. The adjustment is stopped when all preset closed loop conditions are met, and the current parameters are maintained to continue the scanning process.

[0019] Compared with existing technologies, the advantages of this invention are as follows: This invention shapes a single femtosecond laser beam into a multi-focus array using a DOE (Displacement Optical Array), enabling synchronous processing of multi-channel cladding waveguides and significantly improving processing efficiency; the multi-focus array is obtained by modulating the same laser beam using a unified DOE, effectively improving the symmetry and consistency of the cladding waveguide structure; the use of a replaceable DOE structure facilitates rapid switching between different beam arrangements and different cladding structure parameters, resulting in high system flexibility; the processing only requires controlling the sample to move in a single direction, with simple control logic, making it easy to automate and scale up fabrication; it is applicable to various transparent dielectric materials and has broad application prospects in the fields of integrated optics and photonic devices. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart illustrating a parallel fabrication method for cladding optical waveguides based on femtosecond laser and DOE collaboration, provided in an embodiment of the present invention. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] See Figure 1 As shown in some embodiments of this application, this embodiment provides a parallel fabrication method for cladding optical waveguides based on femtosecond laser and DOE collaboration, including the following steps: S100: Collect specific category data of transparent dielectric materials, extract design parameter data of cladding optical waveguide, obtain calibration parameter data of DOE, and determine the initial parameter preset values ​​of femtosecond laser based on the three types of data; S200: The laser emitting component is activated to output a femtosecond pulse laser according to the preset value of the initial parameters, and the spot size of the laser beam and the effective aperture size of the laser incident end face are collected. The femtosecond pulse laser is expanded and collimated according to the matching degree of the spot size and the effective aperture size. S300: It uses replaceable optical elements to perform spatial phase modulation on the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multi-focal spot array. S400: The two-dimensional multifocal light spot array is focused to a preset position inside the transparent substrate material by a focusing lens group or a microscope objective, forming a high energy density region inside the transparent substrate material; S500: While being irradiated by a femtosecond pulsed laser, the transparent substrate material is controlled to move at a constant speed in a linear motion along a preset direction according to a preset processing path, so that the multi-focus laser array can scan synchronously in the interior of the transparent substrate material along the preset direction, forming multiple continuously distributed modification trajectories. S600: Collect cross-sectional coordinate data of the multiple modified trajectories, and determine whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data; If so, continue to maintain the current motion speed of the transparent substrate material and the output parameters of the femtosecond laser. When multiple modified trajectories are distributed around the cross section to form a cladding structure, stop scanning to obtain the final multiple cladding optical waveguide structures. If not, adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop conditions.

[0023] In this embodiment, the parameters of the femtosecond laser include pulse width, repetition frequency, single pulse energy, and average power; the specific category data of the transparent dielectric material includes light transmission characteristics and structural compactness data; the design parameter data of the cladding waveguide includes the number of cladding layers and the cross-sectional shape data of the light guide core; the calibration parameter data of the DOE includes the number of focal points, spatial arrangement, effective aperture size, phase modulation accuracy, and focal energy distribution ratio.

[0024] It is understood that the parallel fabrication method for cladding waveguides based on femtosecond laser and DOE collaboration provided in this embodiment can achieve parallel fabrication of cladding waveguides, significantly improving processing efficiency. By decomposing a single laser beam into a two-dimensional multi-focus array using DOE, multiple modification trajectories can be formed simultaneously in a single scan. Compared to traditional single-focus point-by-point scanning methods, processing time can be significantly shortened, making it particularly suitable for scenarios requiring large-scale fabrication of waveguide arrays. Simultaneously, by precisely controlling the initial parameters of the femtosecond laser, beam expansion and collimation, spatial phase modulation, and the movement path and velocity of the transparent substrate material, this method ensures the precise distribution accuracy of multiple modification trajectories across the cross-section, guaranteeing good consistency and stability of the fabricated cladding structure, thereby improving the optical performance and reliability of the cladding waveguide. Furthermore, the replaceable optical element design increases the system's flexibility, allowing for convenient adjustment of the number and arrangement of sub-beam focal points according to different waveguide design requirements, adapting to the fabrication of various cladding waveguide structures and enhancing the method's versatility and practicality.

[0025] Specifically, determining the preset values ​​of the initial parameters for the femtosecond laser based on three types of data includes: The three types of data are correlated and matched, and the initial preset values ​​of the femtosecond laser parameters are determined through the data correspondence. When the product of single pulse energy and repetition frequency is greater than the preset value of average power, either single pulse energy or repetition frequency is reduced so that the product equals the preset value of average power. When the product of the single pulse energy and the repetition frequency is less than the preset value of the average power, either the single pulse energy or the repetition frequency is increased so that the product equals the preset value of the average power.

[0026] In this embodiment, when associating and matching the three types of data to establish the data correspondence, the initial parameter preset values ​​of the femtosecond laser's pulse width, repetition frequency, single pulse energy, and average power are determined by combining the constraint relationship of "single pulse energy × repetition frequency = average power".

[0027] Understandably, the modification effect of femtosecond lasers on transparent dielectric materials (the degree of permanent refractive index change) depends on the synergistic adaptation of laser parameters with material properties, processing requirements, and DOE performance. The structural compactness of the transparent dielectric material determines the energy threshold required for induced modification, while its light transmission characteristics affect the laser energy absorption efficiency. Design parameters such as the number of cladding layers and the arrangement of optical waveguides determine the number of focal points and energy distribution requirements for processing. Calibration parameters such as the number of focal points and energy distribution ratio of the DOE limit the upper limit of energy and the uniformity of distribution of a single sub-beam. Therefore, it is necessary to establish the correspondence between each data dimension and laser parameters by correlating the three types of data to ensure that the initially determined laser parameters can meet the synergistic requirements of material modification, structural forming, and DOE modulation.

[0028] Understandably, the average power, as a key constraint, has a preset value derived from extensive experimental data and theoretical analysis, directly impacting the fabrication quality and efficiency of the optical waveguide. When the product exceeds the preset value, it means that the energy acting on the material per unit time is too high, potentially leading to localized overheating, ablation, or even damage to the waveguide's structural integrity. Therefore, it's necessary to reduce one of the parameters to balance the energy output. Conversely, when the product is less than the preset value, the laser energy may be insufficient to effectively modify the material, failing to form the desired optical waveguide structure. In this case, increasing the single-pulse energy or repetition frequency increases the energy injection per unit time, ensuring the material reaches the necessary physicochemical change conditions, thus laying a solid energy foundation for the subsequent parallel fabrication of the cladding waveguide. By adjusting these parameters, the femtosecond laser induces a nonlinear absorption effect within the transparent medium, achieving permanent modification of the material's local refractive index. This dynamic adjustment mechanism makes the initial parameter settings of the femtosecond laser more scientific and precise, adaptable to different material properties and fabrication requirements.

[0029] Specifically, the laser emission activation component outputs a femtosecond pulse laser according to the preset initial parameter values ​​and acquires the spot size of the laser beam, including: Set fixed acquisition points along the laser output path; The laser beam's major and minor axis lengths are collected using a spot detection component, and the time interval between the collection moment and the laser start-up moment is recorded. When the ratio of the acquired laser major axis length to the minor axis length is greater than the preset ratio, the position of the laser emission port is adjusted, and the spot size is acquired again. When the ratio of the major axis length to the minor axis length is less than or equal to the preset ratio, the spot size data is stored directly.

[0030] Understandably, the aforementioned process of acquiring and adjusting the laser spot size is a crucial step in ensuring good beam quality of the femtosecond pulsed laser before it enters the subsequent optical processing unit. The preset ratio is set based on the symmetry requirements of the laser spot in the optical waveguide fabrication. For example, for circular or near-circular spots, the preset ratio can be set to a value close to 1, such as 1.1 or 1.2. By real-time monitoring of the major and minor axes of the laser beam at a fixed acquisition point and calculating their ratio, it is possible to quickly determine whether the ellipticity of the current laser beam is within an acceptable range. If the actual ratio is greater than the preset ratio, it indicates that the spot shape is skewed and lacks symmetry, requiring correction; if the actual ratio is less than or equal to the preset ratio, it indicates that the spot symmetry meets the requirements of subsequent processing and no adjustment is needed.

[0031] Understandably, when the actual ratio is greater than the preset ratio, the laser emission port position adjustment mechanism is activated to fine-tune the spatial position of the emission port (including position correction in the front-back, left-right, and up-down directions). After each adjustment, keeping the laser output parameters unchanged, the long axis length and short axis length of the light spot at the fixed acquisition point are re-acquired by the spot detection component, the new actual ratio is calculated, and compared with the preset ratio again. This "adjustment-acquisition-comparison" cycle is repeated until the calculated actual ratio is less than or equal to the preset ratio, at which point the adjustment of the emission port position stops. When the actual ratio of the long axis length to the short axis length of the light spot meets the preset requirement (less than or equal to the preset ratio), the currently acquired long axis length, short axis length, and calculated equivalent diameter data are classified and stored to establish a light spot size dataset. This dataset will be directly transmitted to subsequent stages for matching degree calculation with the effective aperture size of the laser incident end face, providing a basis for beam expansion and collimation processing. It can also be used for quality traceability and process optimization analysis throughout the entire fabrication process, ensuring that the initial beam state of each laser emission is within a controllable and compliant range, thus laying a solid foundation for the high-precision parallel fabrication of subsequent optical waveguides.

[0032] Specifically, the effective aperture size of the laser incident end face includes: The length and width data of the effective aperture of the laser inlet are collected using a dimensional measuring component, and the equivalent diameter of the effective aperture is calculated. Calculate the ratio of the equivalent diameter of the light spot size to the equivalent diameter of the effective aperture to determine the degree of matching between the two; When the ratio is less than the lower limit of the preset matching degree range, the beam expansion ratio is increased to increase the output spot size. When this ratio is greater than the upper limit of the preset matching degree range, the beam expansion ratio is reduced to decrease the output spot size; During the beam expansion process, the collimation component is activated simultaneously to correct the propagation direction of the laser beam, so that the beam propagation direction is perpendicular to the incident end face of the subsequent optical element.

[0033] In this embodiment, the equivalent diameter of the light spot size is calculated using the same area equivalence principle. The ratio of the equivalent diameter of the light spot size to the equivalent diameter of the effective aperture is calculated to obtain the matching ratio, and this ratio and the corresponding two equivalent diameter data are recorded. When the matching ratio is less than the lower limit of a preset range, it indicates that the light spot size is too small, and the beam expansion ratio of the beam expander system needs to be increased; when the matching ratio is greater than the upper limit of a preset range, it indicates that the light spot size is too large, and the beam expansion ratio of the beam expander system needs to be decreased.

[0034] It is understandable that the aforementioned matching degree calculation and beam expansion / collimation adjustment process is not completed in one go, but rather is a dynamic feedback closed-loop control process. After each adjustment of the beam expanding lens group, the system re-collects the major and minor axis lengths of the laser spot before DOE incidence through the spot detection component, recalculates its equivalent diameter, and performs a new ratio calculation and matching degree judgment with the effective aperture equivalent diameter of the laser incident end face. If the new ratio still does not fall within the preset matching degree range, the beam expansion ratio of the beam expanding system is increased or decreased accordingly based on the relationship between the ratio and the upper and lower limits, and collimation correction is performed simultaneously until the ratio of the equivalent diameter of the spot to the effective aperture equivalent diameter stabilizes within the preset matching degree range. This continuous dynamic adjustment mechanism ensures that the size of the laser beam can achieve optimal coupling with the effective aperture of the laser incident end face before entering the DOE for beam splitting, maximizing the utilization of laser energy, improving laser energy utilization efficiency, and avoiding energy waste or leakage. This ensures both the uniformity of the spatial distribution of the incident beam and the accuracy of its propagation direction, providing crucial optical parameter guarantees for the subsequent DOE to efficiently and accurately generate a predetermined number and distribution of sub-beams, and ultimately achieve high-precision parallel fabrication of the cladding waveguide.

[0035] Specifically, the method of using replaceable optical elements to spatially phase modulate the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multi-focal spot array, includes: The replaceable optical element is fixed in the preset position of the optical path by a detachable connection, ensuring that the phase modulation area of ​​the optical element is aligned with the transmission center line of the laser beam, so that the expanded laser beam is perpendicularly incident on the phase modulation area of ​​the optical element. The laser beam is segmented by the phase distribution of optical elements; Specifically, based on the cross-sectional shape of the light-guiding core in the design requirements of the cladding waveguide, the optical elements are controlled to decompose the laser beam into sub-beam focal points arranged in corresponding shapes, forming a two-dimensional multi-focal spot array of corresponding shapes.

[0036] In this embodiment, when the cross-sectional shape of the light-guiding core in the cladding waveguide design is circular, the optical elements are controlled to decompose the laser beam into sub-beam focal points arranged in a ring, forming a circular two-dimensional multi-focal spot array. When the cross-sectional shape of the light-guiding core in the cladding waveguide design is rectangular, the optical elements are controlled to decompose the laser beam into sub-beam focal points arranged in a rectangular ring, forming a rectangular two-dimensional multi-focal spot array. The spatial coordinates and energy distribution data of each sub-beam focal point in the two-dimensional multi-focal spot array are recorded to provide a reference for subsequent focusing and scanning.

[0037] It is understandable that the phase distribution of optical elements is not a fixed, single pattern, but can be flexibly designed and customized according to actual fabrication needs. Besides the annular arrangement and rectangular surrounding sub-beam focal points corresponding to the circular and rectangular cross-sectional shapes of the cladding waveguide, when the cross-section of the cladding waveguide has other specific shape requirements, such as triangles, polygons, or even some irregular structures with specific functions, it is only necessary to design and replace the optical elements with matching phase distributions accordingly to achieve specific segmentation and modulation of the laser beam, thereby generating a two-dimensional multi-focal spot array with a preset spatial arrangement pattern that matches the cross-sectional shape of the target waveguide core. This design approach, based on the replaceability of optical elements and the programmability of phase distribution, can meet the parallel fabrication needs of cladding waveguides with different structural parameters and cross-sectional shapes, laying a solid foundation for the subsequent precise and efficient fabrication of waveguide cores that meet design requirements within optical materials. Meanwhile, the precise recording of the spatial coordinates and energy distribution data of each sub-beam focal point ensures that the subsequent focusing system can accurately capture and control each sub-beam, and that each focal point can work together according to the preset path and energy parameters during the scanning process, thus ensuring the consistency and repeatability of the multi-focal spot array during the internal processing of materials.

[0038] Specifically, the step of focusing the two-dimensional multifocal light array onto a predetermined position inside the transparent substrate material via a focusing lens group or a microscope objective to form a high-energy-density region inside the transparent substrate material includes: Install the focusing lens group or microscope objective on the transmission path of the two-dimensional multifocal spot array, and adjust the distance between the focusing element and the optical element to a preset distance; The surface coordinates of the transparent substrate material are collected by the position detection component, and the axial movement distance of the focusing element to the target position is calculated by combining the preset focusing depth. When half the thickness of the transparent substrate material is less than the preset focusing depth, the placement angle of the transparent substrate material is adjusted first, and then the focusing element is driven to move along the axis to the target position. When half the thickness of the transparent substrate material is greater than or equal to the preset focusing depth, the focusing element is directly driven to move axially to the target position. After the focusing element moves to the target position, it focuses the two-dimensional multi-focus beam array to a preset position inside the transparent substrate material, and each sub-beam focal point forms an independent high-energy-density region inside the material.

[0039] In this embodiment, the depth coordinates and size data of each high energy density region are recorded.

[0040] It is understood that a focusing element is an optical component used to converge a two-dimensional multifocal light spot array to a predetermined position inside a transparent substrate material, including a focusing lens group or a microscope objective.

[0041] In this embodiment, the preset focusing depth is the vertical distance between the target focusing position of the two-dimensional multi-focus spot array inside the transparent substrate material and the surface of the material, determined according to the structural design requirements of the cladding waveguide.

[0042] In this embodiment, the specific process for forming a high energy density region is as follows: Based on the transmission characteristics of the two-dimensional multifocal spot array, the focal length parameters of the focusing element, and the processing accuracy requirements of the cladding waveguide, a preset distance is determined between the focusing element and the optical element (DOE). The focusing element is driven to move axially via a displacement adjustment mechanism until the actual distance between the focusing element and the optical element equals the preset distance. The position of the focusing element is then fixed, completing the initial optical path calibration.

[0043] The position detection component is activated to collect coordinates from multiple points on the surface of the transparent substrate material. The average value is taken as the final coordinate data of the material surface, reducing single-point detection errors. The preset focusing depth parameter is retrieved and calculated with the material surface coordinates to determine the distance the focusing element needs to move axially (axial movement distance = preset focusing depth + material surface coordinate offset, the specific calculation logic is based on the optical path coordinate system setting). This axial movement distance data is recorded.

[0044] The thickness data of the transparent substrate material is collected, and half of the material thickness is calculated and compared with the preset focusing depth. When the preset focusing depth is greater than half of the material thickness, the angle adjustment mechanism of the material support component is activated to adjust the placement angle of the transparent substrate material (the angle adjustment range is determined based on the beam transmission path optimization requirements), so that the transmission path of the laser beam inside the material is closer to a straight line, reducing the scattering effect; when the preset focusing depth is less than or equal to half of the material thickness, there is no need to adjust the material placement angle, and the material is maintained in its initial placement state.

[0045] Based on the calculated axial movement distance, the displacement drive mechanism of the focusing element is activated, driving the focusing element to move at a constant speed along the laser beam transmission direction (axial direction). During the movement, the actual position data of the focusing element is collected in real time through the position feedback component, compared with the target position, and the movement trajectory is dynamically corrected to ensure that the focusing element moves accurately to the target position. When the actual position of the focusing element coincides with the target position, the drive mechanism is stopped, and the final position of the focusing element is fixed.

[0046] After the focusing element is fixed, the two-dimensional multi-focus beam array is converged by the focusing element, penetrates the surface of the transparent substrate material, and is precisely focused to a preset position inside. Each sub-beam focal point forms an independent high-energy-density region inside the material, and the spatial arrangement of each region is consistent with the preset form of the two-dimensional multi-focus beam array. The data recording component is activated to collect and store the depth coordinates (vertical distance from the material surface) and size (cross-sectional dimensions) of each high-energy-density region, forming a high-energy-density region dataset, which provides a reference for subsequent scanning processing and parameter optimization.

[0047] Specifically, the design parameter data of the cladding waveguide also includes the number of cladding waveguides and the arrangement plan; The process involves controlling the transparent substrate material to move at a uniform linear speed along a preset direction according to a preset processing path, so that the multi-focus light spot array scans synchronously along the preset direction inside the transparent substrate material, forming multiple continuously distributed modified trajectories, including: The coordinates of the starting point, ending point, and turning point of the preset processing path are planned based on the number and arrangement density of the cladding waveguides. The displacement control component is connected to the component carrying the transparent substrate material, and moves according to the preset processing path; While the femtosecond pulsed laser is continuously irradiating the material, the displacement control component is activated, driving the supporting component to move the transparent substrate material in a uniform linear motion along a preset direction.

[0048] In this embodiment, the preset direction is preferably a direction perpendicular to the plane where the multi-focus array is located, so that the multi-focus array can scan synchronously along this direction inside the material.

[0049] Understandably, during the motion, the actual position data fed back by the displacement control component is received in real time and compared with the coordinate data of the preset processing path to dynamically correct the motion parameters, ensuring that the material's motion trajectory is consistent with the preset path. Simultaneously, a femtosecond pulsed laser continuously irradiates the material, and a two-dimensional multi-focus beam array scans synchronously within the material. Each sub-beam focus forms a continuously distributed modification trajectory within the material, and the distribution pattern of the trajectory is consistent with the planned arrangement of the cladding waveguide.

[0050] Understandably, in this process, it is crucial to ensure that the speed of the transparent substrate material matches the pulse frequency of the femtosecond laser, the energy distribution of the multifocal spot, and the laser modification threshold of the material itself. This is to guarantee the continuity and consistency of each modification trajectory and avoid poor local modification results due to speed fluctuations or energy instability, which in turn affect the transmission performance of the optical waveguide.

[0051] Specifically, the step of collecting cross-sectional coordinate data of the multiple modified trajectories and determining whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data includes: During the scanning process, the cross-sectional coordinate data of multiple modified trajectories are collected at preset fixed intervals by the cross-sectional detection component; When the cross-sectional coordinates of the modified trajectory satisfy the preset closed loop condition, it is determined that the multiple modified trajectories are distributed in a loop on the cross-section. If the cross-sectional coordinates of multiple modified trajectories do not meet the preset closed loop condition, it is determined that the multiple modified trajectories are not distributed around the cross-section.

[0052] In this embodiment, the preset fixed interval is determined based on the length of the cladding waveguide and the processing accuracy requirements. This interval, either spatial or temporal, is used to collect cross-sectional coordinate data, ensuring data coverage of the entire trajectory without any local omissions. The cross-sectional coordinate data is a set of spatial coordinates representing the edge contour of each modified trajectory within a cross-section perpendicular to the extension direction of the modified trajectory, reflecting the distribution pattern of the trajectory on the cross-section.

[0053] Understandably, the preset closed loop conditions are retrieved, the core judgments included in these conditions are clarified, and the cross-sectional coordinate data collected each time are compared with the preset closed loop conditions one by one to determine whether the trajectory distribution of the current cross-section meets all the judgment items. This comparison operation is performed on the data of all collected cross-sections throughout the process to avoid the situation where some parts meet the conditions but the whole does not.

[0054] Specifically, the determination that the preset closed loop condition is met includes: The cross-sectional coordinate data of each modified trajectory collected are sorted sequentially according to the circumferential direction to form the actual trajectory coordinate sequence; When the following four requirements are met: the distance between the first and last coordinate points in the actual trajectory coordinate sequence is less than the preset overlap threshold, the spacing between two adjacent modified trajectories is within the preset spacing range, there are no gaps in any modified trajectories, and the surrounding area formed by multiple modified trajectories surrounds the cross-sectional area of ​​the preset light guide core, then the preset closed surrounding condition is satisfied. If any one of the four requirements is not met, the preset closed loop condition is deemed not to be met.

[0055] In this embodiment, the preset overlap threshold is the critical distance value for determining whether the beginning and end of the trajectory are closed. It is determined based on the closure requirements of the cladding structure and serves as a quantitative standard for endpoint overlap. The preset spacing range is the allowable spacing fluctuation range between two adjacent modified trajectories. It is determined based on the uniformity requirements of the cladding structure thickness to ensure structural consistency. The preset light guide core cross-sectional area is determined according to the design requirements of the cladding waveguide. The contour range of the light guide core on the cross-section is the benchmark for determining whether the surrounding area is effective.

[0056] Understandably, the preset closed-loop conditions are to ensure that the cladding waveguide fabricated by femtosecond laser and DOE can form a complete, continuous, and structurally stable surrounding cladding structure. The distance between the coordinates of the first and last ends is less than a preset overlap threshold, ensuring the closure of each modified trajectory and preventing gaps in the waveguide cladding due to trajectory disconnection, thus preventing light leakage. The spacing between adjacent modified trajectories is within a preset range to ensure the uniformity and consistency of the spatial distribution of multiple modified trajectories, ensuring a balanced constraint of the cladding on the light guide core and avoiding optical field distortion caused by excessively large or small local spacing. The requirement that all modified trajectories have no gaps further guarantees the integrity of the cladding structure as a whole, as any gap could become a channel for light energy loss. The cross-sectional area of ​​the surrounding region formed by multiple modified trajectories enclosing the preset light guide core clarifies that the spatial position of the cladding must completely cover the light guide core, which is the basis for achieving effective light transmission in the core region. These four requirements together constitute a rigorous judgment system. Only when all conditions are met can it be confirmed that the fabricated cladding structure meets the design expectations and can provide reliable assurance for the optical waveguide's guiding performance. If any one of the requirements is not met, it means that the cladding structure has defects, which may affect the transmission efficiency, mode control, or long-term stability of the optical waveguide. Therefore, it is necessary to readjust the fabrication parameters or perform secondary processing until all preset conditions are met.

[0057] Specifically, the determination that the preset closed loop condition is met also includes: Retrieve a preset cladding structure closed path coordinate sequence, calculate the straight-line distance between each position point in the actual trajectory coordinate sequence and the corresponding position point in the preset closed path coordinate sequence, and obtain all the calculated straight-line distances as a distance dataset; Determine whether there is a gap in the modified trajectory based on the distance dataset and the preset distance deviation threshold; If at least one distance value in the distance dataset is greater than a preset deviation distance threshold, it is determined that there is a gap in the modified trajectory. When all distance values ​​in the distance dataset are less than or equal to a preset deviation threshold, it is determined that there is no gap in the modified trajectory.

[0058] In this embodiment, the specific process for determining whether there is a gap in the modified trajectory is as follows: A preset cladding structure closed path coordinate sequence corresponding to the design parameters of the currently processed cladding waveguide is retrieved. This sequence is completely consistent with the preset surrounding direction and size specifications of the modified trajectory, ensuring the accuracy of the comparison benchmark. If the cladding design parameters are changed during processing, the corresponding preset coordinate sequence is updated and retrieved synchronously. For each acquisition section's actual trajectory coordinate sequence, the corresponding position points in the preset cladding structure closed path coordinate sequence are extracted one by one according to the coordinate point sorting order (matched by the same sorting index). The straight-line distance between each pair of corresponding points is calculated using the spatial distance calculation formula. All calculation results are organized according to the coordinate point sorting order to form a distance dataset.

[0059] Retrieve a preset deviation distance threshold and compare each distance value in the distance dataset with this threshold. Count the number of distance values ​​in the distance dataset that are greater than the preset deviation distance threshold. If the number is zero, it is preliminarily determined that the modified trajectory of this section has no gaps; if the number is greater than zero, it is preliminarily determined that gaps exist.

[0060] For sections where gaps are initially identified, locate all coordinate points whose distance values ​​exceed a preset deviation threshold. Integrate the actual trajectory areas corresponding to these coordinate points to determine the specific coordinate locations of the gap (starting and ending coordinates). Count the number of coordinate points covered by the gap area, calculate the length range of the gap, and classify and store the data such as the gap's coordinate location, the number of covered coordinate points, and the length range to form a gap analysis report, which is then fed back to the control unit.

[0061] The above steps are performed on all acquisition sections. If no distance value in the distance data of all sections is greater than the preset deviation distance threshold, it is finally determined that there is no gap in any modified trajectory. If any section has the above situation, it is finally determined that there is a gap in the modified trajectory, and the corresponding gap analysis report is associated and stored.

[0062] Specifically, adjusting the motion speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop condition includes: Retrieve the cross-sectional coordinate data, distance dataset, spacing, and gap determination results of the modified trajectory that does not meet the preset closed loop conditions, and analyze to determine the specific type of failure to meet the preset closed loop conditions; Adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser according to the type of failure to meet the preset closed surround condition; After each adjustment, the cross-sectional coordinate data of the modified trajectory are re-acquired, and it is determined again whether all preset closed loop conditions are met. The adjustment is stopped when all preset closed loop conditions are met, and the current parameters are maintained to continue the scanning process.

[0063] In this embodiment, the specific process of adjusting the movement speed of the transparent substrate material or the output parameters of the femtosecond laser is as follows: Retrieve all relevant data, including cross-sectional coordinate data, distance datasets, adjacent trajectory spacing records, and gap analysis reports, for any data that does not meet the preset closed loop conditions. Perform a comprehensive analysis on this data, matching each of the four requirements of the preset closed loop conditions to determine the specific type of non-compliance: if the spacing exceeds the range, it is classified as "uneven spacing"; if the distance dataset contains data exceeding the threshold, it is classified as "gap"; if the endpoint distance is greater than the preset overlap threshold, it is classified as "endpoint non-overlapping"; and if the loop does not cover the core, it is classified as "insufficient range".

[0064] If it is "uneven spacing type": If the spacing is greater than the upper limit of the preset range, reduce the movement speed of the transparent substrate material, keep the laser output parameters unchanged, re-acquire the trajectory cross-sectional coordinate data, and calculate the new spacing; If the spacing is less than the lower limit of the preset range, increase the movement speed of the transparent substrate material and repeat the above acquisition and calculation operations; If it is a "gap type": Based on the gap analysis report, if the energy in the area corresponding to the distance value that exceeds the preset deviation threshold in the data set is insufficient, then adjust the single-pulse energy parameters of the laser. If the modification range in the region is too large, causing the trajectory to deviate and form a gap, then reduce the single pulse energy parameter of the laser, keep the motion speed constant, re-acquire the cross-sectional coordinate data and generate a new distance dataset, and determine again whether there is a gap in the modified trajectory; If it is a "endpoints not coinciding type": If the misalignment distance is positively correlated with the movement speed of the transparent substrate material, then the movement speed is finely adjusted; If the misalignment distance is positively correlated with the laser repetition frequency, then the laser repetition frequency is finely adjusted, and the endpoint coordinates are re-acquired and the distance is calculated after the adjustment. If it is "insufficient range type": If the surrounding range is too small, while adjusting the laser single pulse energy, the movement speed is adjusted proportionally to expand the coverage of the modified trajectory, the surrounding area data is re-acquired and judged to ensure that the trajectory covers the preset light guide core cross section range. After each adjustment, the cross-sectional coordinate data of the modified trajectory is re-acquired by the cross-sectional detection component. The straight-line distance, spacing, endpoint distance and wrapping range between the actual trajectory coordinate sequence and the preset cladding structure closed path coordinate sequence are calculated. It is then determined whether all preset closed wrapping conditions are met. The above analysis, adjustment, acquisition and determination operations are repeated until all preset closed wrapping conditions are met. The adjustment is then stopped, and the current parameters are maintained to continue the subsequent scanning and processing.

[0065] It can be seen that developing targeted adjustment plans based on the specific type of problem can avoid blind debugging, significantly improve the efficiency of parameter adjustment, and shorten the processing cycle. Closed-loop adjustment and judgment logic ensures that the adjustment effect can be verified in real time, avoiding processing errors caused by inadequate or excessive adjustment, and guaranteeing the final quality of the cladding structure. It adapts to various scenarios where conditions are not met and can handle multiple coexisting problems simultaneously, enhancing the method's adaptability and flexibility. Complete recording of the parameter adjustment trajectory facilitates the traceability and optimization of subsequent processing parameters, improving the consistency and stability of batch production. The entire adjustment process is automated, requiring no manual intervention, adapting to the needs of large-scale, automated processing, and reducing labor costs and operational complexity.

[0066] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program goods. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program goods embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program goods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0068] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for parallel fabrication of cladding optical waveguides based on femtosecond laser and DOE synergy, characterized in that, include: Collect specific category data of transparent dielectric materials, extract design parameter data of cladding optical waveguide, obtain calibration parameter data of DOE, and determine the initial parameter preset values ​​of femtosecond laser based on the three types of data; The laser emitting component is activated to output a femtosecond pulse laser according to the preset initial parameter values, and the spot size of the laser beam and the effective aperture size of the laser incident end face are collected. The femtosecond pulse laser is expanded and collimated according to the matching degree of the spot size and the effective aperture size. Replaceable optical elements are used to spatially phase modulate the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multifocal beam array. The two-dimensional multifocal light spot array is focused onto a predetermined position inside the transparent substrate material by a focusing lens group or a microscope objective, forming a high energy density region inside the transparent substrate material; While being irradiated by a femtosecond pulsed laser, the transparent substrate material is controlled to move in a uniform linear motion along a preset direction according to a preset processing path, so that the multi-focus laser array can scan synchronously in the interior of the transparent substrate material along the preset direction, forming multiple continuously distributed modification trajectories. Collect cross-sectional coordinate data of the multiple modified trajectories, and determine whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data; If so, continue to maintain the current motion speed of the transparent substrate material and the output parameters of the femtosecond laser. When multiple modified trajectories are distributed around the cross section to form a cladding structure, stop scanning to obtain the final multiple cladding optical waveguide structures. If not, adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop conditions.

2. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 1, characterized in that, The parameters of the femtosecond laser include pulse width, repetition frequency, single pulse energy, and average power; The specific category data of the transparent medium material includes data on light transmission properties and structural density; The design parameters of the cladding waveguide include the number of cladding layers and the cross-sectional shape of the light guide core. The calibration parameters of the DOE include the number of focal points, spatial arrangement, effective aperture size, phase modulation accuracy, and focal point energy distribution ratio. The process of determining the initial parameter preset values ​​for the femtosecond laser based on three types of data includes: The three types of data are correlated and matched, and the initial preset values ​​of the femtosecond laser parameters are determined through the data correspondence. When the product of single pulse energy and repetition frequency is greater than the preset value of average power, either single pulse energy or repetition frequency is reduced so that the product equals the preset value of average power. When the product of the single pulse energy and the repetition frequency is less than the preset value of the average power, either the single pulse energy or the repetition frequency is increased so that the product equals the preset value of the average power.

3. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 2, characterized in that, The laser emission unit is activated to output a femtosecond pulse laser according to the preset initial parameter values, and to acquire the spot size of the laser beam, including: Set fixed acquisition points along the laser output path; The laser beam's major and minor axis lengths are collected using a spot detection component, and the time interval between the collection moment and the laser start-up moment is recorded. When the ratio of the acquired laser major axis length to the minor axis length is greater than the preset ratio, the position of the laser emission port is adjusted, and the spot size is acquired again. When the ratio of the major axis length to the minor axis length is less than or equal to the preset ratio, the spot size data is stored directly.

4. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 3, characterized in that, The effective aperture size of the laser incident end face includes: The length and width data of the effective aperture of the laser inlet are collected using a dimensional measuring component, and the equivalent diameter of the effective aperture is calculated. Calculate the ratio of the equivalent diameter of the light spot size to the equivalent diameter of the effective aperture to determine the degree of matching between the two; When the ratio is less than the lower limit of the preset matching degree range, the beam expansion ratio is increased to increase the output spot size. When this ratio is greater than the upper limit of the preset matching degree range, the beam expansion ratio is reduced to decrease the output spot size; During the beam expansion process, the collimation component is activated simultaneously to correct the propagation direction of the laser beam, so that the beam propagation direction is perpendicular to the incident end face of the subsequent optical element.

5. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 4, characterized in that, The method of using replaceable optical elements to perform spatial phase modulation on the expanded laser beam, decomposing the single laser beam into multiple spatially separated sub-beam focal points to form a two-dimensional multi-focal spot array, includes: The replaceable optical element is fixed in the preset position of the optical path by a detachable connection, ensuring that the phase modulation area of ​​the optical element is aligned with the transmission center line of the laser beam, so that the expanded laser beam is perpendicularly incident on the phase modulation area of ​​the optical element. The laser beam is segmented by the phase distribution of optical elements; Specifically, based on the cross-sectional shape of the light-guiding core in the design requirements of the cladding waveguide, the optical elements are controlled to decompose the laser beam into sub-beam focal points arranged in corresponding shapes, forming a two-dimensional multi-focal light spot array of corresponding shapes.

6. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 5, characterized in that, The process of focusing the two-dimensional multifocal light array onto a predetermined position inside the transparent substrate material via a focusing lens group or microscope objective to form a high energy density region inside the transparent substrate material includes: Install the focusing lens group or microscope objective on the transmission path of the two-dimensional multifocal spot array, and adjust the distance between the focusing element and the optical element to a preset distance; The surface coordinates of the transparent substrate material are collected by the position detection component, and the axial movement distance of the focusing element to the target position is calculated by combining the preset focusing depth. When half the thickness of the transparent substrate material is less than the preset focusing depth, the placement angle of the transparent substrate material is adjusted first, and then the focusing element is driven to move along the axis to the target position. When half the thickness of the transparent substrate material is greater than or equal to the preset focusing depth, the focusing element is directly driven to move axially to the target position. After the focusing element moves to the target position, it focuses the two-dimensional multi-focus beam array to a preset position inside the transparent substrate material, and each sub-beam focal point forms an independent high-energy-density region inside the material.

7. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 6, characterized in that, The step of collecting cross-sectional coordinate data of the multiple modified trajectories and determining whether the multiple modified trajectories are distributed around the cross-section based on the cross-sectional coordinate data includes: During the scanning process, the cross-sectional coordinate data of multiple modified trajectories are collected at preset fixed intervals by the cross-sectional detection component; When the cross-sectional coordinates of the modified trajectory satisfy the preset closed loop condition, it is determined that the multiple modified trajectories are distributed in a loop on the cross-section. If the cross-sectional coordinates of multiple modified trajectories do not meet the preset closed loop condition, it is determined that the multiple modified trajectories are not distributed around the cross-section.

8. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 7, characterized in that, The determination that the preset closed loop condition is met includes: The cross-sectional coordinate data of each modified trajectory collected are sorted sequentially according to the circumferential direction to form the actual trajectory coordinate sequence; When the following four requirements are met: the distance between the first and last coordinate points in the actual trajectory coordinate sequence is less than the preset overlap threshold, the spacing between two adjacent modified trajectories is within the preset spacing range, there are no gaps in any modified trajectories, and the surrounding area formed by multiple modified trajectories surrounds the cross-sectional area of ​​the preset light guide core, then the preset closed surrounding condition is satisfied. If any one of the four requirements is not met, the preset closed loop condition is deemed not to be met.

9. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 8, characterized in that, The determination that the preset closed loop condition is met also includes: Retrieve a preset cladding structure closed path coordinate sequence, calculate the straight-line distance between each position point in the actual trajectory coordinate sequence and the corresponding position point in the preset closed path coordinate sequence, and obtain all the calculated straight-line distances as a distance dataset; Determine whether there is a gap in the modified trajectory based on the distance dataset and the preset distance deviation threshold; If at least one distance value in the distance dataset is greater than a preset deviation distance threshold, it is determined that there is a gap in the modified trajectory. When all distance values ​​in the distance dataset are less than or equal to a preset deviation threshold, it is determined that there is no gap in the modified trajectory.

10. The parallel fabrication method of cladding optical waveguide based on femtosecond laser and DOE synergy according to claim 9, characterized in that, Adjusting the motion speed of the transparent substrate material or the output parameters of the femtosecond laser until the trajectory coordinates meet the preset closed loop condition includes: Retrieve the cross-sectional coordinate data, distance dataset, spacing, and gap determination results of the modified trajectory that does not meet the preset closed loop conditions, and analyze to determine the specific type of failure to meet the preset closed loop conditions; Adjust the movement speed of the transparent substrate material or the output parameters of the femtosecond laser according to the type of failure to meet the preset closed surround condition; After each adjustment, the cross-sectional coordinate data of the modified trajectory are re-acquired, and it is determined again whether all preset closed loop conditions are met. The adjustment is stopped when all preset closed loop conditions are met, and the current parameters are maintained to continue the scanning process.

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