Common reference optical interconnect micro-module, system and packaging method

Abstract

This invention discloses a common-reference optical interconnect micromodule, system, and packaging method. A complementary mechanical mating interface is provided on the outer side of the micromodule's shell, and an optical waveguide end face penetrating the shell is positioned on the mating surface of the mating interface; the optical waveguide and the mating interface share a common reference. While adjacent micromodules complete mechanical mating and positioning, the optical waveguide end faces on both sides automatically align and establish an optical interconnect link; mechanical assembly and optical link establishment are completed synchronously. This invention adopts an external light source architecture, with the light source centrally integrated into the peripheral packaging components. The micromodule body does not integrate the light source; the optical signal is transmitted through the external optical waveguide. This solution eliminates the active alignment process of traditional optical interconnects, reducing manufacturing costs and maintenance difficulty. It supports flexible configuration into two-dimensional planar arrays or three-dimensional stacked arrays and can be widely applied in high-performance computing clusters, optical switching networks, and other scenarios.

Description

Technical Field

[0001] This invention belongs to the fields of photonic integration, three-dimensional optical interconnection, and modular computing architecture, specifically relating to a common-reference optical interconnection micromodule, a corresponding packaging system, and a packaging method. This application, along with four other applications filed on the same day, constitutes a complete next-generation autonomous and controllable computing power full-stack technical solution, with this application undertaking the optical interconnection hardware architecture and high-speed interconnection functions. Background Technology

[0002] Optical interconnects, with their advantages of high bandwidth, low latency, low electromagnetic interference, and strong anti-crosstalk capabilities, are gradually replacing traditional electrical interconnects as the mainstream interconnect solution for high-end computing clusters. Currently, mainstream optical interconnect products generally adopt a module-integrated light source design, where the laser, optical waveguide, and modulator are integrated within the same module. This design has three major drawbacks: First, manufacturing costs are high and yield rates are low. The yield rate of lasers is significantly lower than that of passive optical waveguide devices. The failure of a single laser will render the entire module unusable, significantly increasing the overall cost. At the same time, the difficulty in aligning the light source coupling of multi-channel arrays further reduces the mass production yield.

[0003] Secondly, maintenance is difficult. Light sources are consumable active devices, and when a failure occurs, the entire module or even the entire array needs to be disassembled for replacement, resulting in high maintenance costs and long downtime, which cannot meet the high availability requirements of data centers.

[0004] Third, the assembly complexity is high. The coupling and alignment of traditional optical modules requires a high-precision six-axis displacement stage in conjunction with active optical power feedback. The alignment time for a single channel is long, the equipment cost is high, and it seriously restricts the efficiency of mass production.

[0005] Existing passive alignment solutions relax alignment tolerances through structures such as V-grooves and mode converters. However, the mechanical positioning structure and the optical waveguide structure are manufactured in separate steps, resulting in large cumulative tolerances that cannot meet the high-precision alignment requirements of single-mode optical waveguides. At the same time, existing modular optical interconnect structures mostly adopt a single connection form, which cannot simultaneously meet multiple requirements such as stacking expansion, shock-resistant fixation, and convenient assembly and disassembly.

[0006] Therefore, there is an urgent need in this field for a new modular optical interconnect architecture that can eliminate active alignment processes, reduce manufacturing costs, and improve the ease of operation and maintenance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a common-reference optical interconnect micromodule, system, and packaging method. The core inventive concept lies in: setting the optical waveguide and complementary mechanical interlocking interface to a common reference, utilizing the positioning accuracy of the mechanical interlocking to achieve automatic alignment of the optical waveguide end face, eliminating the need for active optical calibration; and integrating the light source uniformly on an external packaging component, eliminating the need for a light source within the micromodule itself, thus decoupling active and passive devices.

[0008] Furthermore, the interlocking interface adopts a differentiated design of dovetail groove lateral interlocking and top and bottom plug-in, taking into account both the structural stability of the array and the convenience of operation and maintenance.

[0009] Furthermore, the waveguide end face integrates a mode conversion structure, which expands the alignment tolerance and reduces the requirements for machining precision.

[0010] Furthermore, the peripheral packaging components incorporate a wavelength routing controller, which enables dynamic routing and switching of optical signals through wavelength modulation, thereby constructing a global three-dimensional optical interconnect network.

[0011] Compared with the prior art, the present invention has the following beneficial effects: Cost reduction and efficiency improvement, and increased yield: The external centralized arrangement of the light source avoids the problem of overall module scrapping caused by low laser yield, which greatly reduces the manufacturing cost of micro-modules and improves mass production yield.

[0012] Simplified assembly process: The optical waveguide is automatically aligned by relying on the positioning accuracy of mechanical fitting. Light passes through immediately after fitting, eliminating the need for high-precision active alignment and significantly improving assembly efficiency.

[0013] The ease of operation and maintenance is greatly improved: when the light source fails, only the corresponding packaged component needs to be replaced, without disassembling the entire micro-module array, resulting in low maintenance costs and short downtime.

[0014] High scalability: Supports two-dimensional planar splicing and three-dimensional stacking expansion, with bandwidth capacity increasing linearly with the number of modules, adapting to computing power systems of different scales.

[0015] Full-process self-control: The core manufacturing processes are all mature technologies, do not rely on imported high-end equipment, and can achieve self-control of the entire industrial chain. Attached Figure Description

[0016] Figure 1 This is a three-dimensional schematic diagram of the common reference optical interconnect micromodule of the present invention; Figure 2 This is a top view of the dovetail groove fitting interface on the side of the micro-module; Figure 3 A front view schematic diagram of the interlocking interface of the stacked micro-modules; Figure 4 A schematic diagram illustrating the principle of establishing a communication link after adjacent micro-modules are interlocked; Figure 5 A schematic diagram of the planar array + stacked assembly structure and the airflow direction of the heat dissipation channel + optical coupling path; Figure 6 This is a three-dimensional schematic diagram of the entire stacked micro-modules (8*8*4). Figure 7 3D schematic diagram of peripheral packaging system components Figure 8 An exploded view of the fully integrated encapsulation structure; Figure 9 A three-dimensional schematic diagram showing the complete encapsulation process. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0018] I. Core Design Principles The core principle of this invention is to unify the mechanical positioning reference and the optical alignment reference into the same reference system, thereby eliminating the cumulative tolerance between the mechanical structure and the optical structure from the root, and reducing the optical interconnect alignment to a simple assembly of the mechanical structure.

[0019] The optical waveguide and the complementary mechanical interlocking interface share a common reference system, ensuring that the coaxiality deviation of the two optical waveguide end faces meets the optical coupling efficiency requirements after the mechanical interlocking is in place. This common reference system can be implemented using various mature technologies, which can be selected by those skilled in the art based on material, cost, and accuracy requirements. Typical implementation methods include, but are not limited to: Integrated etching process: Through semiconductor photolithography, MEMS deep reactive ion etching and other processes, mechanical interlocking interface structure and optical waveguide positioning groove are simultaneously processed on the same wafer substrate, and the two share the same photolithography mask and the same processing coordinate system; Common reference precision assembly and adjustment: First, the outer shell substrate and the prefabricated optical waveguide device are processed separately, and then assembled and fixed with the same reference using high-precision tooling fixtures to ensure that the relative positional deviation of the two meets the coupling requirements.

[0020] The micromodule itself does not integrate a light source; the optical signal is provided centrally by a light source module on the peripheral packaging component. This architecture achieves decoupling between active and passive components: the micromodule, as a passive / low-activity component, has high yield, low cost, and long lifespan; the light source, as a vulnerable active component, is centrally located on the packaging component for easy replacement and maintenance.

[0021] II. Examples of Optical Interconnect Micromodules In a preferred embodiment, the micromodule adopts a cubic shell with a side length ranging from 3mm to 10mm, and is made of single-crystal silicon, quartz, or low-loss polymer materials. Each of the six sides of the shell is provided with a set of complementary mechanical interlocking interfaces, the sides have a dovetail interlocking structure, and the top and bottom have a uniform cross-section plug-in structure, which has fourfold rotational symmetry and supports four assembly orientations.

[0022] The optical waveguide penetrates the interior of the housing, with its end face located in the central region of the mating surface of the interface. Depending on the application scenario, the following two typical optical waveguide solutions can be selected: Example 1: The silicon-based single-mode optical waveguide is fabricated using silicon-on-insulator (SOI) technology. The core material is single-crystal silicon, and the cladding material is silicon dioxide. The waveguide structure is ridge-shaped or strip-shaped, with a core width of 400nm~600nm and a core thickness of 200nm~300nm. The operating wavelength covers common communication bands such as 1310nm and 1550nm. An inverted conical mode converter is integrated at the end face of the optical waveguide, expanding the mode field diameter to 2μm~5μm and significantly improving the alignment tolerance: when the lateral alignment deviation is ±1μm, the coupling loss increment is less than 0.5dB, greatly reducing the requirements for machining accuracy. The optical waveguide transmission loss is ≤0.1dB / cm.

[0023] Example 2: The polymer multimode optical waveguide is fabricated using polymer materials. The core material is SU-8 or an epoxy-based photosensitive polymer, and the cladding material is a low-refractive-index polymer. The core cross-sectional dimensions are 10μm×10μm to 50μm×50μm, supporting multimode transmission. This scheme offers a large alignment tolerance, with a coupling loss increment of less than 1dB when the lateral deviation is ±5μm. It also has lower requirements for machining precision, resulting in low manufacturing costs and making it suitable for short-to-medium distance, high bandwidth density applications.

[0024] The internal casing can integrate functional modules, including electro-optic modulators, photodetectors, computing units, and storage units, to achieve optical signal to electrical signal conversion and data processing. These functional modules can be manufactured using mature semiconductor processes, without relying on advanced process nodes.

[0025] III. Common Reference Machining Process Examples Example 3: The integrated etching common reference process uses the same photomask and a single deep reactive ion etching (DRIE) process to simultaneously process the mechanical interlocking interface and the optical waveguide positioning groove.

[0026] Process reference: The wafer flat edge and crystal orientation are used as global positioning references, and all patterns are designed based on the same coordinate system; Process steps: ① Wafer thermal oxidation growth of hard mask layer; ② Photolithography, simultaneously defining the mating interface contour and waveguide trench pattern; ③ DRIE etching, by controlling the window area ratio of the two patterns, utilizing the etching load effect to simultaneously form structures of different depths: mating interface etching depth 100μm~500μm, waveguide trench etching depth 5μm~20μm; ④ Deposition of lower cladding, core layer, and upper cladding materials; ⑤ Chemical mechanical planarization (CMP) to complete the waveguide fabrication; Precision control: photolithography alignment accuracy ±10nm, etching uniformity ±3%, and final lateral relative deviation ≤100nm, which is much smaller than the alignment tolerance of a single-mode optical waveguide. End face treatment: The mating surface is chemically and mechanically polished, the optical waveguide end face is coplanar with the mating surface, and the end face roughness is ≤1nm, reducing end face reflection loss.

[0027] Example 4: The nanoimprint common reference process uses silicon or glass as the substrate. First, a mating interface structure and an optical waveguide reference groove are fabricated. Using the positioning surface of the mating interface as the imprint reference, a polymer optical waveguide pattern is imprinted within the reference groove using a UV-cured nanoimprint process. This solution is lower in cost and suitable for large-scale mass production.

[0028] IV. Examples of Light Source Coupling and Packaging Systems Multiple optical interconnect micro-modules are assembled through interlocking interfaces to form a two-dimensional planar array or a three-dimensional stacked array. The outer periphery is equipped with an active optical routing base, side sealing plates and top sealing plates, forming a fully interlocking fastener-free packaging system.

[0029] Example 5: The top surface of the active optical routing base of the VCSEL light source coupling structure is provided with a fitting positioning slot that matches the micro-module. Each positioning slot integrates a light source module, preferably a vertical cavity surface emitting laser (VCSEL) array.

[0030] Light source parameters: single channel rate 10Gbps~25Gbps, wavelength 850nm or 1310nm, array size 4~32 channels; Coupled optics: Each VCSEL is configured with a microlens to collimate the outgoing beam and couple it to the input waveguide end face; the microlens and VCSEL are packaged with the same reference. Tolerance compensation: An elastic silicone pad is installed in the positioning groove to provide ±10μm axial tolerance compensation, ensuring optimal coupling efficiency between the light source and the waveguide end face when the fit is in place; Maintainability: The light source module adopts a pluggable design, which can be removed and replaced individually in case of failure without disassembling the micro-module array, and the replacement time is less than 1 minute.

[0031] Example 6: Interlayer optical interconnection in three-dimensional stacking In a three-dimensional stacking scenario, interlayer optical interconnection achieves a 90° optical path bend through a vertical waveguide paired with a 45° reflective mirror.

[0032] The vertical waveguide runs through the top and bottom surfaces of the micromodule and intersects with the side horizontal waveguides internally; The 45° reflective surface is formed by oblique etching at the waveguide intersection and is coated with a highly reflective metal film or dielectric film to achieve total internal reflection of horizontal and vertical light. Common reference design: The vertical waveguide and the top and bottom surface mating interface are machined with a common reference to ensure that the vertical waveguide end face is automatically aligned when the upper and lower modules are mated. Coupling performance: Single-stage transition loss ≤1dB, supports multi-level stacking expansion.

[0033] Example 7: The active optical routing base of the global three-dimensional wavelength routing system integrates a wavelength routing controller, and the micro-module integrates a tunable micro-ring resonator array, which is coupled to the optical waveguide.

[0034] Micro-ring resonators can change the resonant wavelength through thermal tuning or electro-optic tuning to achieve the downloading and uploading of signals at specific wavelengths; The wavelength routing controller adjusts the resonant wavelength of each micro-ring by configuring signals, establishing a direct optical link from any source module to any target module, without the need for intermediate modules to forward the signal step by step. Wavelength channels: 4~32, single wave rate 25Gbps, total bandwidth of a single waveguide can reach the Tbps level.

[0035] The side and top sealing plates integrate optical routing channels and heat dissipation ducts. The heat dissipation ducts adopt a dual-zone decoupling design consistent with the electrical interconnection system, and ordinary air cooling can meet the heat dissipation requirements.

[0036] Example 8: Three Combination Methods This embodiment provides three optical interconnect combination architectures to adapt to different computing power requirements. All of them are based on the common reference splicing assembly and splicing to complete the optical alignment of the present invention. The difference lies in the combination of the light source layout and the optical path exchange structure inside the micro-module, which can adapt to three-dimensional micro-module arrays of different sizes.

[0037] Small-scale computing power: The top, bottom, and four side panels of the encapsulation system each house a single-channel light source module; the micro-modules contain only optical waveguides running straight through all six sides, with no optical path switching components or optical path steering structures at the center. External light source outputs optical signals that are directly coupled into the coaxially arranged waveguides of the micro-modules. The optical signals can only be transmitted in a straight line along a single axis. Data interaction across planes and layers requires sequential forwarding along the micro-modules within the array, relying on wavelength division multiplexing (WDM) to carry multiple data streams in a time-division manner. The overall structure is simple to manufacture and suitable for small-scale 3D computing arrays with few nodes and low parallel computing loads.

[0038] Medium-capacity computing: Each surface of the encapsulated component still uses a single-channel light source module; each micro-module integrates an optical path switching module at its center, labeled as the optical path core in the attached diagram. This optical path switching module has six sets of optical ports, each connecting to one of the six optical waveguides, and internally integrates a 45° total reflection mirror array and a tunable micro-ring resonator. After the external single-channel light source directly illuminates the input optical signal, the signal can either be transmitted directly along the original optical path or, with the help of the 45° reflector, undergo a 90° optical path reversal, enabling optical link interconnection between micro-modules in any dimension, both horizontally and vertically. By leveraging wavelength multiplexing to enhance the data carrying capacity of a single optical path, it can meet the computing power transmission requirements of medium-sized 3D arrays and conventional graph computation and inference tasks.

[0039] Large-scale ultra-high computing power: The top, bottom, and all side panels of the packaging system are equipped with array-type light source modules. The light source array corresponds one-to-one with the micro-modules in the three-dimensional array. Each light source channel independently and directly connects to the optical waveguide end face of a single micro-module. The aforementioned central optical path switching module is retained inside the micro-module. Each micro-module is equipped with a dedicated, physically isolated independent incident optical channel. All array micro-modules can synchronously and in parallel complete optical signal transmission and reception, without bandwidth loss caused by channel preemption or serial forwarding. Combined with the central optical path switching module, flexible optical path scheduling across planes and layers is achieved. The overall total transmission bandwidth increases linearly with the number of micro-modules deployed, which can support high-concurrency ultra-high computing power service scenarios such as large-layer three-dimensional stacked arrays, massive three-state parallel evolution, and large-scale matrix operations.

[0040] V. Packaging Method Examples The complete packaging process consists of three steps: Step 1, Micro-module array assembly: According to the target topology and scale, optical interconnect micro-modules are sequentially assembled through complementary mechanical interlocking interfaces to form a two-dimensional planar array or a three-dimensional stacked array of a preset scale. The assembly process requires no optical alignment equipment, only mechanical interlocking. Step 2, Packaging component assembly: The active optical routing base is interlocked with the bottom of the micro-module array, the side sealing plates are inserted vertically into the side of the array and locked using elastic clips, and the top sealing plate is placed on top of the array. Simultaneously, the light source module's output end and the optical waveguide end face are automatically aligned, and the entire system's optical link is automatically established. Step 3, System power-on operation: The light source module outputs an optical signal of a specified wavelength, which is imported into the optical waveguides of each micro-module. Each micro-module completes data interaction and processing through the optical interconnect link, and the wavelength routing controller adjusts the optical signal transmission path according to service requirements. Industrial applicability

[0041] The silicon-based optical waveguide process, MEMS bulk silicon etching process, and VCSEL integration process involved in this invention are all mature technology platforms that can be mass-produced on existing production lines. This invention can be widely applied to scenarios such as data center optical interconnects, high-performance computing, optical switching networks, and artificial intelligence computing clusters, possessing extremely high engineering application value and promising prospects for industrial promotion.

Claims

1. A co-reference optical interconnect micro-module comprising a housing and optical waveguides, characterized in that: The outer side of the housing is provided with at least one set of complementary mechanical mating interfaces, each including a mating tenon and a recessed portion. The mating surface of the complementary mechanical mating interface serves as the end face layout area of ​​the optical waveguide. The optical waveguide penetrates the interior of the housing, with its end faces correspondingly arranged at the mating surface. The optical waveguide and the complementary mechanical mating interface share a common reference setting, meaning they share the same processing and assembly position reference system. After mating, the alignment deviation of the end faces of the two optical waveguides meets the optical coupling efficiency requirements. When adjacent micromodules complete mechanical mating positioning through the complementary mechanical mating interfaces, the end faces of the two optical waveguides automatically align, and the mechanical mating positioning and the establishment of the optical interconnect link are completed synchronously. The micromodule body does not integrate a light source; the optical signal is transmitted from the light source module on the peripheral packaging component through coupling to the optical waveguide via the mating end face.

2. The common-reference optical interconnect micromodule according to claim 1, characterized in that, The complementary mechanical mating interfaces located on the side of the housing adopt a dovetail groove structure, and the adjacent micro-modules form a lateral mechanical interlock after being mated on the side. The complementary mechanical mating interfaces located on the top and bottom surfaces of the housing adopt an equal cross-section concave-convex fit structure, which allows the micro-modules to be inserted, removed and disassembled in the vertical direction.

3. The common-reference optical interconnect micromodule according to claim 1, characterized in that, The rotational symmetry factor N of the complementary mechanical interlocking interface is an integer greater than or equal to 2, and the rotation axis is the central axis of the micromodule perpendicular to the interlocking surface. When adjacent micromodules are assembled at an angle that is an integer multiple of 360° / N around the axis, mechanical interlocking positioning and alignment of the optical waveguide end face can be achieved.

4. The common-reference optical interconnect micromodule according to claim 1, characterized in that, The complementary mechanical interlocking interface, the optical waveguide, and the housing are integrally formed with a common reference.

5. The common-reference optical interconnect micromodule according to claim 1, characterized in that, The end face position corresponding to the mating surface of the optical waveguide and the interlocking interface is integrated with a mode conversion structure formed integrally with the optical waveguide based on the same reference, which is used to expand the alignment tolerance.

6. The common-reference optical interconnect micromodule according to claim 1, characterized in that, The housing also integrates a functional module, which includes at least an electro-optical conversion unit and a photoelectric detection unit; the output end of the electro-optical conversion unit is connected to the optical waveguide path, and the input end of the photoelectric detection unit is connected to the optical waveguide path.

7. A common-reference optical interconnect packaging system, characterized in that, It includes multiple common-reference optical interconnect micromodules as described in any one of claims 1 to 6, and peripheral packaging components; Multiple micro-modules are spliced ​​together through the complementary mechanical interlocking interface to form a two-dimensional planar array and / or a three-dimensional stacked array. Adjacent micro-modules establish optical interconnect links and complete data interaction through optical waveguides. The peripheral packaging component is provided with interlocking positioning slots corresponding to the positions of each micro-module. The interlocking positioning slots integrate light source modules. When the packaging component is interlocked with the micro-module array, the light-emitting end of the light source module is automatically aligned with the optical waveguide end face of the corresponding micro-module, and the optical signal is introduced into the optical waveguide by the light source module.

8. The common-reference optical interconnect packaging system according to claim 7, characterized in that, The peripheral packaging components include an active optical routing base, a side sealing plate, and a top sealing plate, which together form a fully integrated fastener-free packaging system; the active optical routing base integrates a wavelength routing controller for regulating the transmission path of optical signals.

9. A common-reference optical interconnect packaging method, characterized in that, Includes the following steps: S1. Select several common-reference optical interconnect micro-modules as described in any one of claims 1 to 6, and assemble the micro-modules through complementary mechanical interlocking interfaces to form a two-dimensional planar array or a three-dimensional stacked array; S2. Fit the peripheral packaging component integrating the light source module with the assembled micro-module array, and automatically align the light-emitting end of the light source module with the optical waveguide end face of the micro-module; S3. Power on the system, the light source module outputs an optical signal and guides it into the optical waveguide, and each micro-module completes data transmission, computation and storage through the optical interconnect link.

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