An AWG and FA optical fiber coupling method based on reverse light spot positioning

Abstract

The present application relates to the technical field of optical communication device coupling assembly, in particular to an AWG and FA optical fiber coupling method based on reverse light spot positioning; the scheme uses the mainstream AWG three-axis translation platform architecture in the industry, at the same time, the FA end motion mechanism is simplified, the redundant translation axis on the FA side is cancelled, and only three-axis rotation adjustment function is reserved. While meeting the high-precision angle adjustment requirement, the mechanical structure and control logic are simplified, the equipment manufacturing, debugging and maintenance cost is reduced, and it is more suitable for large-scale production application; the present application adopts reverse lighting of high-coherent light source built-in in a sealed jig, uses the mode selection and shaping characteristics of the arrayed waveguide grating to form a Gaussian spot at the chip input end, directly calibrates the real waveguide axis inside the chip with the spot center, and solves the defect that the traditional visual alignment can only identify the appearance and cannot locate the waveguide axis. The coarse alignment precision is greatly improved, and the initial alignment deviation is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of optical communication device coupling and assembly technology, and in particular to an AWG and FA fiber coupling method based on reverse spot positioning. Background Technology

[0002] As a core passive optical device in wavelength division multiplexing communication systems, the coupling alignment accuracy between the arrayed waveguide grating (AWG) and the fiber array (FA) directly determines the overall insertion loss, crosstalk index, and mass production yield of the device. It is an extremely critical process in the packaging and manufacturing of optical devices.

[0003] Currently, mainstream AWG and FA coupled assembly equipment in the industry generally adopts a split-axis group structure. The standard configuration is as follows: the AWG chip side uses a three-axis translation platform, which only realizes linear displacement adjustment in the X, Y, and Z axes and does not have angular rotation function; the FA fiber side uses a six-axis adjustment platform, which integrates three-axis translation and three-axis rotation functions. This layout is a common standard structure in the industry, and it is rare to use a dual-sided six-axis full-degree-of-freedom adjustment scheme. Dual-sided six-axis structures are mostly used in high-end scientific research experimental equipment.

[0004] In actual production processes, the existing coupling process still follows the pattern of visual coarse alignment followed by active fine-tuning of optical power. Due to the inherent structural limitations of AWG, its internal waveguides are completely embedded within the chip substrate. The waveguide arrangement trajectory and central axis cannot be directly observed from the chip end face. Existing visual coarse alignment can only identify external mechanical features such as chip shape, positioning slots, FA ferrules, and optical sockets, and can only achieve a rough alignment at the shape level. It cannot accurately calibrate the actual waveguide central axis, resulting in significant positional and angular deviations between the waveguide axis and the optical fiber output axis even after coarse alignment.

[0005] To eliminate alignment errors caused by coarse alignment, existing processes can only rely on a six-axis platform on the FA side to perform a large-scale traversal scan to search for peak light intensity. This not only results in long coupling calibration time and low production efficiency, but also makes it easy to find local light intensity extremes in multi-channel array waveguide coupling scenarios, making it impossible to lock the globally optimal coupling point. Ultimately, this leads to problems such as high device coupling loss and poor batch consistency of products.

[0006] Therefore, it is necessary to propose an improved technical solution to address the above problems. Summary of the Invention

[0007] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0008] A method for coupling an AWG to a FA fiber based on reverse spot positioning includes the following steps: Step 1, Setting up the positioning platform: Construct an AWG three-axis control platform and an FA three-axis control platform. The AWG three-axis control platform is configured to translate along its own X, Y, and Z axes, respectively, and the FA three-axis control platform is configured to rotate around its own X, Y, and Z axes, respectively. A multi-functional AWG positioning fixture is installed on the AWG three-axis control platform. This fixture is used to position the AWG chip and includes a base and a top cover that fit together. The top cover has interlocking soft light-shielding rings on its mating surface. After the base and top cover are closed, a sealed cavity is formed by the soft light-shielding rings. A low-power single-mode laser source and an optical power meter probe that act on the sealed cavity are set on the top cover. A concave positioning notch is set on the soft light-shielding rings. The concave positioning notch is used to fix the AWG chip, so that after the AWG chip is fixed, its output end is located inside the sealed cavity and its input end is located outside the sealed cavity. An FA positioning fixture is set on the FA three-axis control platform. The FA positioning fixture is used to position the FA optical fiber. Step 2, clamping and positioning: Reset the AWG three-axis control platform and the FA three-axis control platform, and arrange the AWG three-axis control platform and the FA three-axis control platform along the plane containing the Z-axis and Y-axis; fix the AWG chip to the multi-functional AWG positioning fixture, fix the FA optical fiber to the FA positioning fixture, and connect the FA optical fiber to the optical socket after positioning it in the FA positioning fixture. Step 3, set up the visual recognition module: set up the first camera module along the normal direction of the Z-Y plane, and set up the second camera module along the normal direction of the Z-X plane. The first camera module and the second camera module are set up to be able to collect the input of the AWG chip. Step 4, Waveguide Axis Positioning: The low-power single-mode laser source and optical socket are activated. The output beam from this source exhibits high spatial coherence. The beam is injected in reverse from the output of the AWG chip, undergoes mode selection, phase calibration, and beam shaping via an arrayed waveguide grating, and finally outputs a Gaussian spot with a regular energy distribution from the input of the AWG chip. Images of the spot emitted from the input of the AWG chip are acquired using the first and second camera modules, and the center of the spot is identified. This center is considered equivalent to the central axis of the AWG chip waveguide. Simultaneously, images of the optical socket of the FA fiber are acquired, and the central axis of the FA fiber is obtained through fitting. Step 5, coarse angle adjustment: Based on the AWG chip waveguide center axis and FA fiber center axis identified in Step 4, the AWG three-axis control platform and FA three-axis control platform are automatically controlled to perform fine attitude adjustment so that the two center axes coincide. The AWG three-axis control platform is then automatically controlled to move along the Z-axis until the AWG chip and FA fiber are tightly connected, thus completing the visual coarse adjustment operation. Step 6, Active Fine-Tuning: Turn off the low-power single-mode laser source, and introduce the forward light source from the FA fiber input end through the optical socket. The forward light source is coupled into the AWG chip waveguide through the FA fiber and exits from the AWG chip output end. The optical power signal of the emitted light is collected in real time by the optical power meter probe and fed back. Based on the optical power feedback signal, the AWG three-axis control platform and the FA three-axis control platform are automatically controlled to perform small-range angle fine-tuning until the optical power reaches the maximum value, thus completing the high-precision adjustment of the coupling angle. Step 7, dispensing and curing: Dispense adhesive on the outside of the joint after the FA fiber and AWG chip are tightly connected. After curing with ultraviolet light, the coupling and fixation are completed.

[0009] Preferably, the attitude fine-tuning performed by the automated control AWG three-axis control platform and the FA three-axis control platform in step 5 includes the following steps: Step 5.1: Establish a unified three-dimensional coordinate system and align the optical axis: The central axis of the AWG chip waveguide identified by the first and second camera modules is used as the alignment optical axis. A three-dimensional spatial coordinate system is established with this alignment optical axis as the reference. At the same time, the input end of the AWG chip is used as the coordinate origin, so that the movement adjustment of the AWG chip and the rotation adjustment of the FA fiber are performed based on this unified three-dimensional coordinate system. Step 5.2, FA fiber angle correction: Based on the alignment optical axis, the tilt angle of the FA fiber output direction in the Z-Y plane is obtained through the first camera module, and the tilt angle of the FA fiber output direction in the Z-X plane is obtained through the second camera module; the FA three-axis control platform is controlled to rotate and compensate around the corresponding axis according to the tilt angle, so that the output direction of the FA fiber is consistent with the alignment optical axis. Step 5.3, AWG chip incident point alignment: The first camera module and the second camera module identify the waveguide incident point of the AWG chip and the output axis of the FA optical fiber. The waveguide incident point is the input end of the AWG chip. Drive the AWG three-axis control platform to translate along the X and Y axes to adjust the waveguide incident point of the AWG chip to the output axis of the FA optical fiber.

[0010] Preferably, step 5, in which the automated control AWG three-axis control platform moves along the Z-axis to achieve tight docking between the AWG chip and the FA optical fiber, includes the following steps: Step 5.4: Obtain the angle between the moving direction of the AWG three-axis control platform and the three-dimensional coordinate system: After step 5.2, drive the AWG three-axis control platform to move a large distance Z1 along the Z-axis. The first and second camera modules identify the position of the FA fiber's output axis on the AWG chip input end face, obtaining the position changes X1 and Y1 of the FA fiber's output axis on the X and Y axes of the three-dimensional coordinate system. Based on Z1, X1, and Y1, substitute them into trigonometric functions: tanα = Z1 / X1; tanβ = Z1 / Y1; α and β are obtained, where α is the angle between the X-axis travel direction of the AWG three-axis control platform and the X-axis of the three-dimensional coordinate system; β is the angle between the Y-axis travel direction of the AWG three-axis control platform and the Y-axis of the three-dimensional coordinate system. Step 5.5: Obtain the movement data of the AWG three-axis control platform along the Z-axis: After adjusting the waveguide injection point of the AWG chip to the output axis of the FA fiber, the length L of the output axis between the AWG chip and the FA fiber is collected by the first and second camera modules. Combined with the already calculated included angles α and β, the compensation movement is calculated using the following formula: X2 = Lcosα; Y2=Lcosβ; Z2 = (Lsinα + Lsinβ) / 2; Wherein, X2 is the X-axis compensated translational travel of the AWG three-axis control platform, Y2 is the Y-axis compensated translational travel of the AWG three-axis control platform, and Z2 is the Z-axis docking travel of the AWG three-axis control platform; Step 5.6, Precise docking operation: Based on the calculated travel data, the AWG three-axis control platform is controlled to move Z2 distance along the Z-axis, and the offset compensation of X2 distance on the X-axis and Y2 distance on the Y-axis is completed synchronously to achieve accurate docking without deviation.

[0011] Preferably, a pivot structure is provided on one side of the base and the top cover. The base is fixedly installed on the AWG three-axis control platform, and the top cover flips on the base through the pivot structure. A locking structure is provided on the other side of the base and the top cover. After the top cover is closed on the base, it is fixed and closed by the locking structure.

[0012] Preferably, the locking structure includes magnets respectively disposed on the top cover and the base, and the top cover and the base are magnetically attracted together by the magnets.

[0013] Preferably, the soft light-shielding ring is made of fluororubber material.

[0014] Preferably, the length of the recessed positioning notch is controlled to be between one-third and one-half of the chip length.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This solution adopts the mainstream AWG three-axis translation platform architecture used in mass production in the industry, while simplifying the motion mechanism on the FA side, eliminating redundant translation axes on the FA side, and retaining only the three-axis rotation adjustment function. While meeting the requirements for high-precision angle adjustment, it simplifies the mechanical structure and control logic, reduces equipment manufacturing, debugging and maintenance costs, and is more suitable for large-scale mass production applications.

[0016] 2. This invention employs a sealed fixture with a built-in high-coherence light source for reverse illumination. Utilizing the mode selection and shaping characteristics of the arrayed waveguide grating, a Gaussian light spot is formed at the chip input end. The center of this light spot directly calibrates the actual waveguide axis inside the chip, overcoming the limitation of traditional visual alignment which can only identify the shape but cannot locate the waveguide axis. This significantly improves coarse alignment accuracy and effectively reduces initial alignment deviation.

[0017] 3. Relying on high-precision pre-alignment, this solution does not require extensive traversal scanning of the FA platform to find peaks. Only a small range of angle fine-tuning is needed to lock the global optimal optical power peak value. This not only shortens coupling time and improves production efficiency, but also avoids the problem of getting trapped in local extrema when coupling multiple channels, effectively reducing device insertion loss and improving product optical performance and batch consistency.

[0018] 4. This invention employs a flip-top magnetic positioning fixture, combined with a fluororubber soft light-shielding ring to form a sealed cavity. This achieves flexible chip clamping, preventing rigid contact from scratching the optical end face; and isolates stray light from the outside, ensuring the accuracy of spot imaging and optical power detection. The fixture allows for partitioned chip arrangement and is compatible with all processes, including reverse positioning, forward light detection, and external adhesive dispensing and curing, demonstrating strong process adaptability.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the coupling method of the present invention; Figure 2 This is a flowchart of step 5 of the present invention; Figure 3 This is a schematic diagram of the structure of the multifunctional AWG positioning fixture and AWG chip in this invention; Figure 4 This is a schematic diagram of the coupling in step 5.1 of the present invention; Figure 5 This is a schematic diagram of the coupling in step 5.2 of the present invention; Figure 6 This is a coupling diagram of step 5.3 of the present invention; Figure 7This is a coupling diagram of step 5.6 of the present invention.

[0022] The reference numerals and names in the figure are as follows: AWG chip 10, FA optical fiber 20, base 30, hinge structure 31, locking structure 32, top cover 40, soft light shield 50, concave positioning notch 51, low power single-mode laser light source 60, optical power meter probe 70, FA positioning fixture 80, first camera module 91, second camera module 92. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1-7 In this embodiment of the invention, an AWG-FA fiber coupling method based on reverse spot positioning includes the following steps: Step 1, Setting up the positioning platform: Construct an AWG three-axis control platform and an FA three-axis control platform. The AWG three-axis control platform is configured to translate along its own X-axis, Y-axis, and Z-axis, respectively, and the FA three-axis control platform is configured to rotate around its own X-axis, Y-axis, and Z-axis, respectively. A multi-functional AWG positioning fixture is installed on the AWG three-axis control platform. The multi-functional AWG positioning fixture is used to position the AWG chip 10. The multi-functional AWG positioning fixture includes a base 30 and a top cover 40 that fit together. Both the base 30 and the top cover 40 have mating surfaces... A series of interlocking soft light-shielding rings 50 are provided. After the base 30 and top cover 40 are closed, a sealed cavity is formed by the soft light-shielding rings 50. A low-power single-mode laser source 60 and an optical power meter probe 70 are provided on the top cover 40, which act on the sealed cavity. A concave positioning notch 51 is provided on the soft light-shielding rings 50. The concave positioning notch 51 is used to fix the AWG chip 10, so that after the AWG chip 10 is fixed, its output end is located inside the sealed cavity and its input end is located outside the sealed cavity. An FA positioning fixture 80 is provided on the FA three-axis control platform. The FA positioning fixture 80 is used to position the FA light. Fiber 20; This step is used to establish the hardware foundation for the entire coupling and adjustment operation, determining the motion coordination form of the AWG three-axis control platform only realizing three-axis translation and the FA three-axis control platform only realizing three-axis rotation; at the same time, the coverable base 30 and top cover 40, together with the soft light-shielding ring 50, form a sealed cavity, and the AWG chip 10 is flexibly fixed by the concave positioning notch 51, so that the two ends of the chip are arranged in sections. After the AWG chip 10 is installed, it forms a moderate compression with the soft light-shielding ring 50, further improving the positioning reliability, and the length range of the concave positioning notch 51 is controlled within the chip length. The range is between one-third and one-half; it can reliably limit and fix the AWG chip 10, while ensuring that the chip's input and output ends are exposed in separate areas and do not interfere with each other's optical paths; the low-power single-mode laser source 60 and the optical power meter probe 70 are integrated and arranged inside the cavity, which can isolate external stray light interference, protect the optical end face of the chip, and allow the components required for optical path positioning and light intensity detection to be laid out in advance. Together with the FA positioning fixture 80, the basic construction of device positioning is completed, providing a stable and reliable installation structure and working conditions for subsequent axis recognition, attitude adjustment and precise coupling.

[0025] In this step, a low-power single-mode laser source 60 is deployed within a sealed cavity. During operation, it emits a highly coherent light source towards the output end of the AWG chip 10. The mode field emitted by this source matches the mode field of the single-mode waveguide of the AWG chip, and the reverse incidence allows for efficient coupling without the need for an additional mode conversion structure. The AWG chip 10 contains an arrayed waveguide grating. The highly coherent light source enters the internal waveguide structure from the output end of the AWG chip 10. After entering the AWG chip 10, the beam first undergoes spatial mode screening via the native single-mode waveguide of the AWG chip 10. The mode cutoff characteristics of the native single-mode waveguide suppress higher-order clutter modes, retaining only the fundamental mode beam for transmission. Subsequently, the arrayed waveguide grating performs phase calibration and beam shaping on the fundamental mode beam path by path, completing mode purification and ultimately forming a clearly defined Gaussian spot at the chip input end. The geometric center of this spot precisely coincides with the actual central axis of the waveguide inside the chip, and can be directly used as an alignment reference to match the output axis of the FA fiber, achieving a visual positioning effect for waveguide axis calibration without directly viewing the internal structure.

[0026] The low-power single-mode laser source 60 and the optical power meter probe 70 need to be properly positioned and their installation orientations must be carefully considered. The low-power single-mode laser source 60 is placed inside a sealed cavity, with the beam collimated and incident directly onto the output face of the AWG chip 10. This ensures efficient beam coupling into the chip waveguide, resulting in a well-formed Gaussian spot at the input end of the AWG chip 10, thus completing the waveguide axis positioning. The low-power single-mode laser source 60 is installed with a slight offset to effectively avoid obstructing the forward light output path of the AWG chip 10. The optical power meter probe 70 is installed facing the forward light output direction of the AWG chip 10 to collect the emitted beam from the forward working optical path. The concave positioning notch 51 on the soft light-shielding ring 50 is aligned with the center of the sealed cavity, ensuring that the output face of the AWG chip 10 is stably positioned within the cavity reference area after clamping. The low-power single-mode laser source 60 integrates a collimating and beam-expanding structure, with an emitted beam coverage area larger than the chip's output surface, accommodating minor positional deviations caused by chip clamping. The optical power meter probe 70 employs a large photosensitive surface combined with a light-collecting structure to fully receive the chip's emitted beam. Both probes have opposite optical paths and operate at different times, with their installation positions not obstructing each other and no optical path interference. Combined with a sealed, light-shielding environment, this ensures clear and stable beam imaging and accurate and reliable optical power detection data, while also not occupying separate workspaces, adapting to different working modes such as initial positioning and subsequent fine-tuning.

[0027] Step 2, Clamping and Positioning: Reset the AWG and FA three-axis control platforms and arrange them along the planes containing the Z and Y axes. Fix the AWG chip 10 onto the multi-functional AWG positioning fixture and the FA fiber optic cable 20 onto the FA positioning fixture 80. After the FA fiber optic cable 20 is positioned on the FA positioning fixture 80, connect it to the optical socket. This step is used to mechanically reset the two control platforms and standardize their arrangement, determine a unified working benchmark, and then perform stable clamping and positioning of the AWG chip 10 and FA fiber optic cable 20 respectively. At the same time, assemble the docking optical socket for the FA fiber optic cable 20, and standardize the installation posture and docking foundation of the components. This effectively ensures that the two are placed in a regular and uniform manner, avoiding initial alignment deviation caused by clamping misalignment. This prepares the materials and assembly for subsequent image acquisition, axis recognition, and optical path conduction adjustment.

[0028] Step 3, setting up the visual recognition module: A first camera module 91 is set up along the normal direction of the Z-Y plane, and a second camera module 92 is set up along the normal direction of the Z-X plane. The first camera module 91 and the second camera module 92 are configured to capture the input end of the AWG chip 10. This step forms a dual-view image acquisition system by deploying two sets of camera modules in different plane normal directions. The system can simultaneously capture the image of the input end of the AWG chip 10 from two different dimensions, and can clearly capture the light spot formed at the input end and the corresponding position status of the FA fiber 20 from all directions, providing reliable visual data support for subsequent axis recognition, angle calculation and attitude correction.

[0029] Step 4, Waveguide Axis Positioning: Turn on the low-power single-mode laser source 60 and optical socket. The low-power single-mode laser source 60 outputs a beam with high spatial coherence. The beam is injected in reverse from the output of the AWG chip 10 and passes through the chip's native single-mode waveguide and the arrayed waveguide grating in synergy: First, the native single-mode waveguide performs spatial mode screening, filtering out higher-order clutter modes based on its inherent mode cutoff characteristics, thus purifying the beam mode; then, the arrayed waveguide grating performs phase calibration and beam shaping, finally outputting a Gaussian beam with a regular energy distribution from the input of the AWG chip 10. The light spot image emitted from the input terminal of the AWG chip 10 is acquired by the first camera module 91 and the second camera module 92. The center of the light spot is identified and is taken as the equivalent central axis of the waveguide of the AWG chip 10. Simultaneously, the optical socket image of the FA fiber 20 is acquired and fitted to obtain the central axis of the FA fiber 20. In this step, a low-power single-mode laser source 60 is injected into the AWG chip 10 in reverse. The AWG chip 10 integrates a single-mode waveguide and an arrayed waveguide grating, which are native structures of the chip and do not require additional mode filtering or mode field matching components. The arrayed waveguide grating is a typical interferometric passive optical device. Combined with the mode constraint capability of the single-mode waveguide, the high spatial coherence beam, after phase matching, mode filtering, and beam shaping, can stably output a fundamental mode Gaussian light spot with clear boundaries and standard Gaussian energy distribution. This solution can complete mode purification and light spot shaping based on the inherent structure of the AWG chip, meeting the requirements of reverse positioning. By using the center of the light spot as the equivalent waveguide axis, high-precision visual positioning is achieved. Mode purification and light spot shaping are completed by using the chip's native single-mode waveguide and arrayed waveguide grating. The center of the light spot is accurately determined by the images acquired by the dual-camera module and is equivalent to the real central axis of the waveguide. At the same time, the central axis of the FA fiber 20 is fitted by combining the image of the optical socket. This effectively breaks through the limitations of traditional positioning based solely on shape and accurately obtains two sets of alignment reference axes, providing accurate data for subsequent attitude correction and axis coincidence alignment.

[0030] Step 5, coarse angle adjustment: Based on the center axis of the AWG chip waveguide and the center axis of the FA fiber 20 identified in Step 4, perform the following operations: Step 5.1, establish a unified three-dimensional coordinate system and alignment optical axis: based on the central axis of the waveguide of the AWG chip 10 identified by the first camera module 91 and the second camera module 92 as the alignment optical axis, a three-dimensional spatial coordinate system is established with the alignment optical axis as the reference. At the same time, the input end of the AWG chip 10 is taken as the coordinate origin, so that the movement adjustment of the AWG chip 10 and the rotation adjustment of the FA fiber 20 are performed based on the unified three-dimensional coordinate system. Step 5.2, FA fiber 20 angle correction: Based on the alignment optical axis, the tilt angle of the light output direction of the FA fiber 20 in the Z-Y axis plane is obtained through the first camera module 91, and the tilt angle of the light output direction of the FA fiber 20 in the Z-X axis plane is obtained through the second camera module 92; according to the tilt angle, the FA three-axis control platform is controlled to rotate and compensate around the corresponding axis so that the light output direction of the FA fiber 20 is consistent with the alignment optical axis; Step 5.3, AWG chip 10 incident point alignment: The first camera module 91 and the second camera module 92 identify the waveguide incident point of the AWG chip 10 and the output optical axis of the FA optical fiber 20. The waveguide incident point is the input end of the AWG chip 10. Drive the AWG three-axis control platform to translate along the X-axis and Y-axis to adjust the waveguide incident point of the AWG chip 10 to the output optical axis of the FA optical fiber 20.

[0031] Step 5.4: Obtain the angle between the moving direction of the AWG three-axis control platform and the three-dimensional coordinate system: After step 5.2, drive the AWG three-axis control platform to move a large distance Z1 along the Z-axis. The first camera module 91 and the second camera module 92 identify the position of the output axis of the FA fiber 20 at the input end face of the AWG chip 10, and obtain the position changes X1 and Y1 of the output axis of the FA fiber 20 on the X and Y axes of the three-dimensional coordinate system. Based on Z1, X1, and Y1, substitute them into trigonometric functions: tanα = Z1 / X1; tanβ = Z1 / Y1; α and β are obtained, where α is the angle between the X-axis travel direction of the AWG three-axis control platform and the X-axis of the three-dimensional coordinate system; β is the angle between the Y-axis travel direction of the AWG three-axis control platform and the Y-axis of the three-dimensional coordinate system. Step 5.5: Acquire the movement data of the AWG three-axis control platform along the Z-axis: After adjusting the waveguide injection point of the AWG chip 10 to the output axis of the FA fiber 20, the length L of the output axis between the AWG chip 10 and the FA fiber 20 is acquired through the first camera module 91 and the second camera module 92. Combined with the already measured included angles α and β, the compensation movement is calculated using the following formula: X2 = Lcosα; Y2=Lcosβ; Z2 = (Lsinα + Lsinβ) / 2; Wherein, X2 is the X-axis compensated translational travel of the AWG three-axis control platform, Y2 is the Y-axis compensated translational travel of the AWG three-axis control platform, and Z2 is the Z-axis docking travel of the AWG three-axis control platform; Step 5.6, Precise docking operation: Based on the calculated travel data, the AWG three-axis control platform is controlled to move Z2 distance along the Z-axis, and the offset compensation of X2 distance on the X-axis and Y2 distance on the Y-axis is completed synchronously to achieve deviation-free and precise docking and complete the visual coarse adjustment operation.

[0032] Based on the two identified central axes, this step first establishes a unified three-dimensional coordinate system and determines the alignment reference by relying on the waveguide central axes. Then, the angle correction of FA fiber 20 and the alignment of the incident point of AWG chip 10 are completed respectively. Next, the angle between the travel direction and the coordinate system is calculated by trial movement of the platform. Combined with the axis spacing, the compensation movement of each axis is accurately calculated using trigonometric functions. Finally, based on the calculation data, the platform is driven to complete multi-axis synchronous compensation movement to achieve deviation-free and precise docking. This completes the visual coarse adjustment, effectively corrects the angle and position deviations, and allows AWG chip 10 and FA fiber 20 to be initially and accurately aligned, greatly reducing the adjustment range and workload of subsequent fine adjustment.

[0033] Step 6, Active Fine-Tuning: The low-power single-mode laser source 60 is turned off. A forward light source is incident from the input end of the FA fiber 20 through an optical socket. The forward light source is coupled into the waveguide of the AWG chip 10 via the FA fiber 20 and exits from the output end of the AWG chip 10. The optical power signal of the emitted light is collected in real time by the optical power meter probe 70 and fed back. Based on the optical power feedback signal, the AWG three-axis control platform and the FA three-axis control platform are automatically controlled to perform small-range angle fine-tuning until the optical power reaches its maximum value, completing the high-precision adjustment of the coupling angle. In this step, the low-power single-mode laser source 60 used for positioning is turned off, and the forward working optical path is switched on for transmission. The integrated optical power meter probe 70 is used to collect the emitted optical power data in real time and generate feedback. Based on the change in optical power value, the two platforms are automatically controlled to perform small-range attitude fine-tuning until the optical power reaches its peak value, thus completing the high-precision coupling calibration, further eliminating the small alignment errors left by the coarse adjustment, locking the optimal coupling state, effectively reducing coupling loss, and ensuring that the optical transmission performance of the device meets the standards.

[0034] Step 7, Adhesive Dispensing and Curing: Adhesive is dispensed onto the outside of the joint gap between the FA fiber 20 and the AWG chip 10 after they are tightly connected. After curing under ultraviolet light, the coupling and fixation are completed. In this step, after high-precision coupling and alignment, adhesive is dispensed onto the outside of the joint gap between the two and the adhesive is cured quickly under ultraviolet light. This can firmly lock the optimal coupling relative position of the AWG chip 10 and the FA fiber 20, prevent subsequent displacement from affecting optical performance, and finally complete the overall assembly and fixation, ensuring the stability of the finished product structure and the accuracy of long-term use.

[0035] Please see Figure 3A pivot structure 31 is provided on one side of the base 30 and the top cover 40. The base 30 is fixedly installed on the AWG three-axis control platform, and the top cover 40 flips on the base 30 via the pivot structure 31. A locking structure 32 is provided on the other side of the base 30 and the top cover 40. After the top cover 40 is closed on the base 30, it is fixed by the locking structure 32. The locking structure 32 includes magnets respectively provided on the top cover 40 and the base 30. The top cover 40 and the base 30 are magnetically attracted by the magnets. The addition of the pivot structure 31 enables the top cover 40 to flip open and close. Combined with the magnetic locking structure 32, it can quickly complete the closing and fixing and opening and disassembly. It is convenient and labor-saving to install and remove the AWG chip 10. The opening and closing positioning is stable and the operation is simple. Fixing the base 30 to the three-axis platform can ensure that the overall installation benchmark is uniform and the positioning position will not be deviated during the opening and closing process. The soft light-shielding ring 50 is made of fluororubber material; it has excellent sealing, flexibility and aging resistance. It can not only fit tightly to form a sealed light-shielding space to effectively block external stray light, but also flexibly buffer and protect the chip end face. At the same time, it is suitable for repeated opening and closing, making it more durable and further improving the ease of use, sealing and overall practicality of the fixture.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for coupling AWG and FA optical fibers based on reverse spot positioning, characterized in that, Includes the following steps: Step 1, Setting up the positioning platform: Construct an AWG three-axis control platform and an FA three-axis control platform. The AWG three-axis control platform is configured to translate along its own X-axis, Y-axis, and Z-axis respectively, and the FA three-axis control platform is configured to rotate around its own X-axis, Y-axis, and Z-axis respectively. A multi-functional AWG positioning fixture is set on the AWG three-axis control platform. The multi-functional AWG positioning fixture is used to position the AWG chip (10). The multi-functional AWG positioning fixture includes a base (30) and a top cover (40) that cover each other. The covering surfaces of the base (30) and the top cover (40) are provided with interlocking soft light-shielding materials. After the ring (50), base (30) and top cover (40) are closed, a sealed cavity is formed by the soft light-shielding ring (50). A low-power single-mode laser source (60) and an optical power meter probe (70) that act on the sealed cavity are provided on the top cover (40). An inward positioning notch (51) is provided on the soft light-shielding ring (50). The inward positioning notch (51) is used to fix the AWG chip (10), so that after the AWG chip (10) is fixed, its output end is located inside the sealed cavity and its input end is located outside the sealed cavity. An FA positioning fixture (80) is provided on the FA three-axis control platform. The FA positioning fixture (80) is used to position the FA optical fiber (20). Step 2, clamping and positioning: Reset the AWG three-axis control platform and the FA three-axis control platform, and arrange the AWG three-axis control platform and the FA three-axis control platform in the plane containing the Z-axis and Y-axis; fix the AWG chip (10) to the multi-functional AWG positioning fixture, fix the FA optical fiber (20) to the FA positioning fixture (80), and connect the FA optical fiber (20) to the optical socket after positioning it to the FA positioning fixture (80); Step 3, set up the visual recognition module: set up the first camera module (91) along the normal direction of the Z-Y plane, and set up the second camera module (92) along the normal direction of the Z-X plane. The first camera module (91) and the second camera module (92) are set up to be able to collect the input of the AWG chip (10). Step 4, waveguide axis positioning: Turn on the low-power single-mode laser source and optical socket. The output beam of the low-power single-mode laser source has high spatial coherence. The beam is injected in reverse from the output end of the AWG chip (10), and the mode selection, phase calibration and beam shaping are completed by the array waveguide grating. Finally, a Gaussian spot with regular energy distribution is output from the input end of the AWG chip (10). The first camera module (91) and the second camera module (92) acquire the light spot image emitted from the input end of the AWG chip (10), identify the center of the light spot, and take the center of the light spot as the equivalent of the central axis of the waveguide of the AWG chip (10); at the same time, the optical socket image of the FA fiber (20) is acquired, and the central axis of the FA fiber (20) is obtained by fitting. Step 5, coarse angle adjustment: Based on the AWG chip (10) waveguide center axis and FA fiber (20) center axis identified in step 4, the AWG three-axis control platform and FA three-axis control platform are automatically controlled to perform attitude fine adjustment so that the two center axes coincide. The AWG three-axis control platform is then automatically controlled to move along the Z-axis to the AWG chip (10) and FA fiber (20) for close docking, thus completing the visual coarse adjustment operation. Step 6, Active Fine-tuning: Turn off the low-power single-mode laser source (60), and incident the forward light source from the input end of the FA fiber (20) through the optical socket. The forward light source is coupled into the waveguide of the AWG chip (10) through the FA fiber (20) and emitted from the output end of the AWG chip (10). The optical power signal of the emitted light is collected in real time by the optical power meter probe (70) and fed back. According to the optical power feedback signal, the AWG three-axis control platform and the FA three-axis control platform are automatically controlled to perform small-range angle fine-tuning until the optical power reaches the maximum value, thus completing the high-precision adjustment of the coupling angle. Step 7, dispensing and curing: Dispensing adhesive on the outside of the joint gap after the FA optical fiber (20) and the AWG chip (10) are tightly connected, and curing is performed by ultraviolet light to complete the coupling and fixation.

2. The AWG-FA fiber coupling method based on reverse spot positioning according to claim 1, characterized in that, Step 5, where the automated control AWG three-axis control platform and the FA three-axis control platform perform attitude fine-tuning, includes the following steps: Step 5.1: Establish a unified three-dimensional coordinate system and align the optical axis: Based on the central axis of the waveguide of the AWG chip (10) identified by the first camera module (91) and the second camera module (92), the alignment optical axis is used as the reference to establish a three-dimensional spatial coordinate system. At the same time, the input end of the AWG chip (10) is used as the coordinate origin, so that the movement adjustment of the AWG chip (10) and the rotation adjustment of the FA fiber (20) are performed based on the unified three-dimensional coordinate system. Step 5.2, FA fiber (20) angle correction: Based on the alignment optical axis, the tilt angle of the light output direction of the FA fiber (20) in the Z-Y axis plane is obtained by the first camera module (91), and the tilt angle of the light output direction of the FA fiber (20) in the Z-X axis plane is obtained by the second camera module (92); the FA three-axis control platform is controlled to rotate and compensate around the corresponding axis according to the tilt angle, so that the light output direction of the FA fiber (20) is consistent with the alignment optical axis; Step 5.3, AWG chip (10) incident point alignment: The first camera module (91) and the second camera module (92) identify the waveguide incident point of the AWG chip (10) and the output axis of the FA optical fiber (20). The waveguide incident point is the input end of the AWG chip (10). Drive the AWG three-axis control platform to translate along the X-axis and Y-axis to adjust the waveguide incident point of the AWG chip (10) to the output axis of the FA optical fiber (20).

3. The AWG-FA fiber coupling method based on reverse spot positioning according to claim 1, characterized in that, Step 5, in which the automated control AWG three-axis control platform moves along the Z-axis to the AWG chip (10) and the FA optical fiber (20) for tight docking, includes the following steps: Step 5.4, obtain the angle between the moving direction of the AWG three-axis control platform and the three-dimensional coordinate system: After step 5.2, drive the AWG three-axis control platform to move a large distance Z1 along the Z-axis. The first camera module (91) and the second camera module (92) identify the position of the output axis of the FA optical fiber (20) on the input end face of the AWG chip (10), and obtain the position changes X1 and Y1 of the output axis of the FA optical fiber (20) on the X and Y axes of the three-dimensional coordinate system; Based on Z1, X1, and Y1, substitute them into the trigonometric functions: tanα = Z1 / X1; tanβ = Z1 / Y1; α and β are obtained, where α is the angle between the X-axis travel direction of the AWG three-axis control platform and the X-axis of the three-dimensional coordinate system; β is the angle between the Y-axis travel direction of the AWG three-axis control platform and the Y-axis of the three-dimensional coordinate system. Step 5.5: Obtain the movement data of the AWG three-axis control platform along the Z-axis: After the waveguide injection point of the AWG chip (10) is adjusted to the output axis of the FA fiber (20), the length L of the output axis between the AWG chip (10) and the FA fiber (20) is collected by the first camera module (91) and the second camera module (92). Combined with the calculated included angles α and β, the compensation movement is calculated using the following formula: X2 = Lcosα; Y2=Lcosβ; Z2 = (Lsinα + Lsinβ) / 2; Wherein, X2 is the X-axis compensated translational travel of the AWG three-axis control platform, Y2 is the Y-axis compensated translational travel of the AWG three-axis control platform, and Z2 is the Z-axis docking travel of the AWG three-axis control platform; Step 5.6, Precise docking operation: Based on the calculated travel data, the AWG three-axis control platform is controlled to move Z2 distance along the Z-axis, and the offset compensation of X2 distance on the X-axis and Y2 distance on the Y-axis is completed synchronously to achieve accurate docking without deviation.

4. The method for coupling AWG and FA optical fibers based on reverse spot positioning according to claim 1, characterized in that, A pivot structure (31) is provided on one side of the base (30) and the top cover (40). The base (30) is fixedly installed on the AWG three-axis control platform. The top cover (40) flips on the base (30) through the pivot structure (31). A locking structure (32) is provided on the other side of the base (30) and the top cover (40). After the top cover (40) is closed on the base (30), it is fixed and closed by the locking structure (32).

5. The AWG-FA fiber coupling method based on reverse spot positioning according to claim 4, characterized in that, The locking structure (32) includes magnets respectively disposed on the top cover (40) and the base (30), and the top cover (40) and the base (30) are magnetically attracted by the magnets.

6. The method for coupling AWG and FA optical fibers based on reverse spot positioning according to claim 1, characterized in that, The soft light-shielding ring (50) is made of fluororubber material.

7. The method for coupling AWG and FA optical fibers based on reverse spot positioning according to claim 1, characterized in that, The length range of the recessed positioning notch (51) is controlled between one-third and one-half of the chip length range.

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