Integrated optical coupling device for co-packaged optics, co-packaged optical module

Abstract

The application relates to a kind of integrated optical coupling devices for co-encapsulation optics, co-encapsulation optical module.The integrated optical coupling device includes: the optical body made of transparent optical material, optical body has light input end face and light output end face and reflecting surface;Beam expander collimation structure is arranged at the light input end face or reflecting surface of optical body, for receiving the first light beam emitted from the coupling port of optical chip, and the first light beam is expanded and collimated as second light beam;Gradient optical waveguide is arranged in the interior of optical body, with starting end and end, starting end is connected with second light beam, end extends to light output end face, the cross-sectional dimension of gradient optical waveguide gradually shrinks from starting end to end;Positioning structure is arranged on optical body, for realizing the passive mechanical alignment between optical body and optical chip and external fiber array.Using the device can improve the alignment tolerance while maintaining low coupling loss, and simplify assembly process.

Description

Technical Field

[0001] This application relates to the field of optoelectronic integrated packaging technology, and in particular to an integrated optical coupling device and a co-packaged optical module for co-packaged optics. Background Technology

[0002] Co-Packaged Optics (CPO) technology integrates optical engines and switching ASIC chips on the same package substrate to shorten electrical interconnect length, reduce power consumption, and increase bandwidth density, and has become an important technology direction in the field of data center interconnects.

[0003] In CPO modules, optical coupling is required between the optical waveguide on the silicon photonic chip and the external standard single-mode fiber. Currently, the industry mainly uses two types of optical coupling schemes: For edge couplers, the mode field is expanded by fabricating a reverse tapered waveguide on the chip end face and then docked with the fiber. Its lateral alignment tolerance is usually less than ±1μm, which requires active alignment process. This process is time-consuming and has high equipment cost, which limits the mass production efficiency of CPO modules; For grating couplers, a periodic grating structure is generally used to couple vertically incident light to the horizontal waveguide inside the chip. Its coupling loss is about 2dB to 4dB and the operating bandwidth is relatively narrow.

[0004] As can be seen, optical coupling and mechanical positioning functions are usually distributed across multiple independent components, increasing the cumulative assembly error. How to improve alignment tolerance while maintaining low coupling loss and simplifying the assembly process is a significant technical challenge in CPO technology. Summary of the Invention

[0005] Therefore, it is necessary to provide an integrated optical coupling device and a co-packaged optical module for co-packaged optics that can maintain low coupling loss while improving alignment tolerance and simplifying the assembly process, in order to address the above-mentioned technical problems.

[0006] In a first aspect, this application provides an integrated optical coupling device for co-packaged optics, comprising:

[0007] An integral optical body made of transparent optical material, the optical body having a light input end face, a light output end face, and a reflective surface;

[0008] A beam expanding and collimating structure is disposed on the light input end face or reflective surface of the optical body to receive a first beam emitted from the optical chip coupling port and expand and collimate the first beam into a second beam.

[0009] A gradient optical waveguide is disposed inside the optical body and has a starting end and an ending end. The starting end is connected to the second light beam, and the ending end extends to the light output end face. The cross-sectional dimensions of the gradient optical waveguide gradually decrease from the starting end to the ending end.

[0010] A positioning structure is disposed on the optical body to achieve passive mechanical alignment between the optical body, the optical chip, and the external fiber array.

[0011] Secondly, this application also provides a co-packaged optical module, comprising:

[0012] Switching chip;

[0013] At least one silicon photonics chip is electrically interconnected with the switching chip, and the silicon photonics chip is provided with at least one coupling port;

[0014] The integrated optical coupling device as described in any one of the first aspects is mounted above or to the side of the silicon photonic chip by passive alignment.

[0015] The fiber optic array is inserted into the positioning hole of the integrated optical coupling device via guide pins.

[0016] Thirdly, this application also provides a method for fabricating an integrated optical coupling device, applied to the integrated optical coupling device as described in the first aspect, wherein the optics are made of silicate material, the method comprising:

[0017] Silicate materials are molded into prefabricated optical bodies with microlens structures and reflective surface prestructures through a molding process;

[0018] An ion-exchange mask is deposited on the surface of the pre-fabricated optical body;

[0019] A waveguide pattern is defined on the ion-exchange mask layer using a photolithography process. The waveguide pattern includes a start-end opening, an end-end opening, and a gradient section opening connecting the two.

[0020] The waveguide core region is formed in the region corresponding to the waveguide pattern by an ion exchange process.

[0021] The waveguide core region is subjected to secondary ion exchange treatment to form a buried graded refractive index waveguide;

[0022] A reflective film is deposited on the pre-structured reflective surface;

[0023] A positioning hole is formed on the optical body;

[0024] The end face of the optical body is optically ground and polished.

[0025] Fourthly, this application also provides a method for fabricating an integrated optical coupling device, applied to the integrated optical coupling device as described in the first aspect, wherein the optical element is made of modified resin, and the method includes:

[0026] Modified resin is molded into an integral pre-fabricated optical body using an injection molding process;

[0027] Graded fiber is fabricated by using a fiber taper process to gradually change the core diameter along the length direction;

[0028] The graded optical fiber is placed into the groove of the pre-fabricated optical body and fixed.

[0029] Remove excess optical fibers protruding from the groove and grind and polish the end face of the optical body;

[0030] A reflective film is deposited on the reflective surface.

[0031] The aforementioned integrated optical coupling devices and co-packaged optical modules for co-packaged optics first expand the narrow-mode field beam emitted from the chip into a collimated large-mode field beam through microlenses or parabolic reflectors, increasing the alignment tolerance in the air gap. Then, the large-mode field is thermally contracted to the standard fiber mode field through a graded waveguide, ensuring efficient coupling of the fiber and resolving the contradiction between low loss and large tolerance. By integrating the beam expansion and collimation structure with the graded waveguide into the same optical body, the assembly process is simplified, and passive alignment and installation at the chip end are achieved. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a vertical optical coupling package structure based on an end-face coupler in one embodiment;

[0034] Figure 2 This is a schematic diagram of a vertical optical coupling packaging structure based on a parabolic reflector in one embodiment;

[0035] Figure 3 This is a schematic diagram of a vertical optical coupling package structure based on a grating coupler in one embodiment;

[0036] Figure 4 This is a schematic diagram of a horizontal optical coupling package structure based on a grating coupler in one embodiment;

[0037] Figure 5 This is a schematic diagram of an optical coupling device structure based on thermally matched resin material in one embodiment;

[0038] Figure 6 This is a process flow diagram of a method for manufacturing a glass optical object in one embodiment;

[0039] Figure 7 This is a process flow diagram of a method for fabricating a modified resin optical body in one embodiment. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0041] In all embodiments of this invention, unless otherwise stated, an optical chip refers to a photonic integrated circuit based on a silicon photonics platform, on which components such as optical modulators, photodetectors, and waveguides are integrated. A coupling port refers to a structure on the optical chip used for inputting and outputting optical signals to the outside, including end-face couplers or grating couplers. Standard single-mode fiber refers to single-mode fiber conforming to ITU-T G.652.D or G.657.A1 standards.

[0042] In one embodiment, the integrated optical coupling device includes:

[0043] The optical element, made of transparent optical material, is a single-piece structure. It has a light input end face, a light output end face, and a reflective surface. The light input end face is positioned opposite the optical chip and is used to receive the emitted light beam. The light output end face is positioned opposite the external fiber array and is used to output the optical signal to the fiber. The reflective surface is located in the optical path inside the optical element, between the beam expander / collimator structure and the graded waveguide. The reflective surface is used to change the propagation direction of the optical signal.

[0044] Furthermore, the coefficient of thermal expansion (CTE) of the optical bulk material is 0.5 × 10⁻⁶ in the range of 0°C to 100°C. -6 / °C to 10×10 -6 / °C, for example, selected from borosilicate glass, aluminosilicate glass, quartz glass, polyetherimide (PEI) resin or glass-resin composite materials, etc.

[0045] A beam expanding and collimating structure is disposed on the light input end face or reflective surface of an optical body to receive the first beam emitted from the coupling port of the optical chip and expand and collimate the first beam into a second beam.

[0046] Beam expansion and collimation refers to increasing the mode field diameter of a light beam while decreasing its divergence angle, thus maintaining a smaller degree of divergence during subsequent propagation. The mode field diameter of the second beam after beam expansion and collimation is larger than that of the first beam.

[0047] Specifically, a flat microlens can be integrally molded onto the light input end face of the optical body. It can be understood that after beam expansion and collimation by this microlens, the second beam can then have its propagation direction changed by reflection from the reflecting surface.

[0048] Alternatively, the beam expanding and collimating structure can be placed on the reflecting surface, and the beam expanding and collimating structure and the reflecting surface can be integrated into a parabolic reflecting surface. The coupling port of the optical chip is located at or near the focal point of the parabolic reflecting surface, so that the diverging first beam emitted from the optical coupler is converted into a second beam that propagates perpendicularly to the diverging beam after being reflected by the parabolic reflecting surface.

[0049] A graded-tone waveguide is disposed inside the optical body. The graded-tone waveguide has a start end and an end end. The start end aligns with the second beam after reflection by the reflective surface, and its end extends to the optical output end face. The cross-sectional dimensions of the graded-tone waveguide gradually taper from the start end to the end end along the direction of optical signal propagation. The cross-sectional dimensions at the start end match the mode field diameter of the second beam after reflection by the reflective surface, allowing the second beam to enter the graded-tone waveguide with low loss. The cross-sectional dimensions at the end match the mode field diameter of a standard single-mode fiber, allowing the beam exiting from the end to couple into the standard single-mode fiber with low loss.

[0050] The positioning structure is mounted on the optical element. The positioning structure is used to achieve relative positioning between the optical element and the optical chip, as well as relative positioning between the optical element and the external fiber optic array.

[0051] The aforementioned integrated optical coupling device integrates four functions—beam expansion and collimation, optical path steering, mode field gradient conversion, and mechanical positioning—into a single, monolithic optical body, solving the problem of accumulated assembly errors caused by the dispersion of these functions among multiple independent components in traditional solutions. By first expanding the beam and then gradually contracting it, both lower insertion loss and larger alignment tolerance can be achieved simultaneously.

[0052] In the following specific embodiments, optical chips with end-face couplers and grating couplers as ports, as well as vertical optical coupling and horizontal optical coupling methods, are described respectively.

[0053] like Figure 1 As shown, in one embodiment, a vertical optical coupling packaging structure based on an end-face coupler is provided. In this embodiment, the optical element 210 is an integral structure made of silicate glass. The beam expanding and collimating structure is specifically a microlens structure, with the microlens 250 integrally formed on the light input end face of the optical element 210.

[0054] Specifically, Figure 1 (a) in the image is the front view after assembly. Figure 1 (b) is the left view of the optical structure. Figure 1 (c) is a top view after assembly. Microlenses 250 are plano-convex lenses, their number corresponding to the number of graded waveguides. Their convex surfaces face the optical chip 100, and their flat surfaces face the interior of the optical body 210. Microlenses 250 have an aperture of 100 μm, a radius of curvature of 200 μm, an effective focal length of approximately 400 μm, and a numerical aperture of approximately 0.15. The exit face of the end-face coupler 110 is located at the edge of the optical chip, and the emitted beam propagates horizontally. The emitted beam propagates horizontally, with an exit mode field diameter (1 / e²) of approximately 3 μm (horizontal) × 2 μm (vertical), and a numerical aperture of approximately 0.35. When the optical chip 100 and the optical body 210 are installed at an appropriate distance, the microlenses 250 convert the diverging beam emitted from the end-face coupler 110 into an approximately parallel beam, completing beam expansion and collimation. The mode field diameter of the second beam after being expanded and collimated by microlens 250 is approximately 25μm×25μm.

[0055] The reflecting surface 240 is a planar reflective inclined surface, disposed inside the optical body 210, located in the optical path between the microlens 250 and the graded waveguide 220. An angle of 40° to 50° is formed between the reflecting surface 240 and the bottom surface of the optical body 210, allowing horizontally incident light beams to propagate vertically after reflection. A metallic reflective film is deposited on the reflecting surface 240. Optionally, this metallic reflective film is a silver film with a thickness of 80 nm, covered with a 50 nm thick silicon dioxide passivation protective layer to prevent oxidation of the silver film.

[0056] The graded-index waveguide 220 is a buried graded-index waveguide formed in a glass substrate through a thermionic exchange process. The starting end 221 is located directly below the reflecting surface 240 and aligns with the second beam reflected by the reflecting surface 240. The mode field diameter of the starting end 221 matches the mode field diameter of the second beam after expansion and collimation by the microlens 250, and is 25 μm × 25 μm. The beam waist of the second beam after expansion by the microlens 250 is located at the end face of the starting end 221 of the graded-index waveguide 220. The graded segment 223 connects the starting end 221 and the ending end 222. The ending end 222 extends to the optical output end face 212 of the optics 210. The mode field diameter of the ending end 222 is approximately 9.5 μm × 9.5 μm, designed to match the mode field diameter of standard SMF-28 single-mode fiber at a wavelength of 1310 nm. From the starting end 221 to the ending end 222, the cross-sectional dimensions of the graded waveguide 220 gradually shrink according to a cosine function profile to meet the thermal coupling conditions. When the length of the graded section is 3.5 mm, the radiation loss caused by mode field mismatch is less than 0.08 dB, and the total waveguide transmission loss is less than 0.2 dB. Each channel of each graded waveguide 220 is isolated from each other by a low-refractive-index glass substrate, and the crosstalk between channels is less than -50 dB.

[0057] The positioning structure includes two positioning right angles 230 disposed on the bottom surface of the optical body 210 and two positioning holes 260 penetrating the optical body 210. The positioning right angles 230 are located at the contact surface between the optical body and the optical chip, specifically two mutually perpendicular precision-machined planes on the bottom surface of the optical body 210, used to cooperate with the corresponding positioning blocks 120 disposed on the optical chip 100. The positioning holes 260 are disposed at the contact surface between the optical body and the fiber array, and are two pin-type precision circular holes penetrating the optical body 210, with a diameter of 0.700mm ± 0.001mm and a positional accuracy of ±1μm. When the positioning guide pin 300 (a standard MT guide pin with a diameter of 0.700mm) is inserted into the positioning hole 260, the optical body 210 can achieve precise mechanical positioning with the standard MT array 400, ensuring that the lateral alignment error between the end 222 and the core of the single-mode fiber 410 is less than 0.5μm.

[0058] In addition, the optical body is provided with a stress buffer structure, which is a flexible pad or groove on the contact surface between the optical body and the optical chip, to absorb the thermal stress between the optical chip and the optical body caused by temperature changes.

[0059] During assembly, the optical element 210 is flip-chip bonded onto the optical chip 100 using a flip-chip bonding machine. An air gap of approximately 300 μm is maintained between the microlens 250 and the light-emitting end face of the optical chip 100. The microlens 250 expands and collimates the emitted beam from the end face coupler 110 into a second beam with a mode field diameter of approximately 25 μm.

[0060] In this embodiment, the first beam is expanded by a microlens, which greatly increases the alignment tolerance in the air gap; then, the large mode field is thermally contracted to the standard fiber mode field by a second-stage graded waveguide, which ensures efficient coupling with the fiber and solves the contradiction between low loss and large tolerance. The effect is better than any single-stage solution. Through the positioning structure, passive alignment assembly between the optical body and the optical chip can be achieved based on a commercial high-precision flip-chip bonding machine.

[0061] like Figure 2 As shown, in one embodiment, a parabolic reflector is provided as an alternative to a lens and a reflective bevel for an end-face coupler.

[0062] Specifically, the difference between this embodiment and the previous embodiment is that the beam expanding and collimating structure is disposed on the reflecting surface of the optical body and integrated with the reflecting surface to form a parabolic reflecting surface, forming a concave parabolic reflector, and the coupling port of the optical chip is located at or near the focal point of the parabolic reflecting surface.

[0063] For example, the parabolic reflector 241 can convert the divergent beam from the coupling port of the optical chip 100 into a parallel beam, while simultaneously achieving beam expansion, collimation, and optical path redirection. The end-face coupler 110 is located at the focal point of the parabolic reflector 241, and its emitted divergent beam is converted into a collimated beam that propagates vertically downward after being reflected by the parabolic reflector 241.

[0064] For example, the parabolic reflector 241 has a focal length f = 300 μm and an aperture diameter of 120 μm. Ray tracing simulations show that this design can convert a beam with an output mode field diameter of approximately 3 μm × 2 μm into a collimated beam with a mode field diameter of approximately 22 μm × 22 μm and a divergence angle of less than 0.5°. Compared to Example 1, this embodiment reduces the number of optical interfaces, theoretically reducing interface reflection loss by approximately 0.1-0.2 dB.

[0065] This embodiment achieves beam expansion and collimation as well as optical path redirection simultaneously through a parabolic reflector, reducing the number of optical interfaces and lowering reflection loss caused by light passing through multiple interfaces.

[0066] like Figure 3 As shown, in one embodiment, a vertical optical coupling package structure with an optical chip coupling port being a grating coupler is also provided.

[0067] like Figure 3As shown in (a), the difference between this embodiment and the previous embodiment is that the optical coupling port on the optical chip 100 is a grating coupler 150, and the horizontally propagating light beam within the optical chip 100 is emitted vertically upward through the grating coupler 150. The grating coupler 150 is a subwavelength grating structure with dimensions of 12μm × 12μm and an output mode field diameter of approximately 10μm × 10μm. The microlens 250 expands and collimates the approximately 10μm mode spot emitted from the grating coupler 150 into a parallel beam with a diameter of approximately 20μm, which then enters the graded waveguide 220. Figure 3 As shown in (b) of this embodiment, when a large mode field grating coupler 155 is used on the optical chip 100 (the output mode field diameter is extended to about 20μm×20μm), the microlens 250 can be omitted.

[0068] Furthermore, in another embodiment, such as Figure 3 As shown in (b), when a large-mode-field grating coupler 155 is used on the optical chip 100 (the output mode field diameter is extended to about 20μm×20μm), the microlens 250 can be omitted, so that the beam emitted from the large-mode-field grating coupler can directly enter the graded optical waveguide 220.

[0069] like Figure 4 In one embodiment, a horizontal optical coupling package structure based on a grating coupler is provided.

[0070] like Figure 4 As shown in (a) of the diagram, in this embodiment, the optical body further includes a reflecting surface 240, which is used to change the propagation direction of the light beam from the vertical direction to the horizontal direction, thereby realizing a horizontal light output layout of the optical fiber. The light beam, after being expanded by the microlens 250, is first reflected from the vertical direction to the horizontal direction by the reflecting surface 240, and then enters the graded waveguide 220. The end 222 of the graded waveguide 220 is located on the side end face 213 of the optical body 210 and is connected to the horizontally placed single-mode optical fiber.

[0071] Furthermore, in another embodiment, such as Figure 4 As shown in (b) as a variant, the microlens 250 and the reflecting surface 240 can be replaced by an off-axis parabolic reflecting surface 270.

[0072] like Figure 5 As shown, in one embodiment, an optical coupling device based on a thermally matched resin material is provided. The optical body 210 is an integral structure, with a microlens 250 integrally formed on the light input end face of the optical body 210. The first light beam emitted from the end face coupler 110 on the optical chip, after being expanded and collimated by the microlens 250, is transmitted to the graded fiber 290 via the reflecting surface 240.

[0073] The positioning structure includes two positioning right angles set on the bottom surface of the optical body 210 and two positioning holes 260 penetrating the optical body 210. The positioning right angles are two mutually perpendicular precision-machined planes set on the bottom surface of the optical body 210, which are used to cooperate with the corresponding positioning blocks 120 set on the optical chip 100.

[0074] Specifically, the optical element 210 in this embodiment is made of modified polyetherimide (PEI) resin, and its coefficient of thermal expansion is approximately 5 × 10⁻⁶ after being adjusted by filler. -6 / °C to 7×10 -6 / °C. The modified PEI resin also exhibits low hygroscopicity and a high glass transition temperature (Tg>200°C). The optical body 210 is integrally formed by precision injection molding and includes a microlens 250, a reflective surface 240, a V-groove 280, and a positioning guide pin 300. The V-groove 280 is used to embed and fix the graded fiber 290. The graded fiber 290 is prepared by fiber tapering, gradually reducing the core diameter from 50 μm to approximately 10 μm.

[0075] In one embodiment, a co-packaged optical module is provided, comprising:

[0076] A switching chip; at least one silicon photonic chip electrically interconnected with the switching chip, the silicon photonic chip having at least one coupling port; an integrated optical coupling device as described in any of the above embodiments, mounted above or to the side of the silicon photonic chip by passive alignment; and an optical fiber array inserted into the positioning hole of the integrated optical coupling device by guide pins.

[0077] In this embodiment, by utilizing the integrated optical coupling device described in the above embodiments, the assembly efficiency and maintainability of the module can be improved while ensuring low-loss transmission of the optical link.

[0078] Based on the same inventive concept, this application also provides a method for fabricating an integrated optical coupling device. The solution provided by this method is similar to the solution described in the above-described integrated optical coupling device. Therefore, the specific limitations of the fabrication method in one or more embodiments provided below can be found in the limitations of the integrated optical coupling device described above, and will not be repeated here.

[0079] In one exemplary embodiment, such as Figure 6 As shown, a method for fabricating an integrated optical coupling device is provided, applicable to the integrated optical coupling device as described in any of the above embodiments, wherein the optical element is made of silicate material, and the method includes the following steps:

[0080] Step S501: The silicate material is molded into a pre-fabricated optical body with a microlens structure and a reflective surface pre-structure through a molding process.

[0081] Step S502: Deposit an ion-exchange mask on the surface of the pre-fabricated optical body.

[0082] Step S503: Define waveguide patterns on the ion-exchange mask layer using photolithography.

[0083] Step S504: A waveguide core region is formed in the region corresponding to the waveguide pattern through an ion exchange process.

[0084] Step S505: Perform secondary ion exchange treatment on the waveguide core region to form a buried graded refractive index waveguide.

[0085] Step S506: Deposit a reflective film on the reflective surface prestructure.

[0086] Step S507: Form a positioning hole on the optical body.

[0087] Step S508: Optical grinding and polishing are performed on the end face of the optical body.

[0088] In another embodiment, such as Figure 7 As shown, a method for fabricating an integrated optical coupling device is provided, applicable to the integrated optical coupling device as described in any of the above embodiments. In this embodiment, the optical element is made of modified resin, and the method includes:

[0089] Step S601: The modified resin is molded into an integral pre-fabricated optical body through injection molding process.

[0090] Step S602: Prepare graded fiber. The core diameter of the graded fiber is gradually changed along the length direction by fiber tapering process.

[0091] Step S603: Place the graded optical fiber into the groove of the pre-fabricated optical body and fix it.

[0092] Step S604: Remove excess optical fiber protruding from the groove and grind and polish the end face of the optical body.

[0093] Step S605: Deposit a reflective film on the reflective surface.

[0094] To facilitate implementation, the following three specific scenarios illustrate the fabrication method of integrated optical coupling devices.

[0095] In one of the first exemplary embodiments, taking the fabrication of a glass optical body as an example, the following implementation method can be adopted:

[0096] Step S701, Master mold preparation. Microlens array male mold and positioning hole punch array are fabricated on a silicon or nickel-based master mold using ultra-precision diamond cutting or photolithography-wet etching processes.

[0097] Step S702, graphite mold preparation. The master mold is transferred into isostatically pressed graphite material, and the surface is coated with a boron nitride (BN) or diamond-like carbon (DLC) release layer.

[0098] Step S703, glass molding. Heating to approximately 650°C under a nitrogen protective atmosphere, applying a molding pressure of approximately 5 MPa, holding the pressure for 30 seconds, and then slowly cooling to room temperature.

[0099] Step S704, ion exchange mask fabrication. A 200 nm thick aluminum thin film is deposited, and the waveguide mask pattern is defined by ultraviolet lithography.

[0100] Step S705, first thermal ion exchange. At 360°C with 0.5 wt% of Mix the molten salt for 40 minutes.

[0101] Step S706, second thermal ion exchange. At 390°C in pure... The buried graded refractive index waveguide is formed by immersing the waveguide in molten salt for 80 minutes.

[0102] Step S707, finishing of the reflective surface. Machining to 45°±0.1°, depositing Cr / Ag / Multilayer film.

[0103] Step S708, precision machining of the positioning holes. Ultraviolet femtosecond laser drilling is used to drill the holes, with a diameter of 0.700±0.001mm.

[0104] Step S709: End face polishing. Where Ra < 5nm.

[0105] Step S710: Cut into slices.

[0106] In a second exemplary embodiment, the optics are made of fused silica. Because fused silica does not contain alkali metal ions, it cannot be directly subjected to conventional methods. - Ion exchange is used, therefore femtosecond laser direct writing (FsLDW) is employed to fabricate graded waveguides. The specific steps are as follows:

[0107] Step S801: Prepare the pre-fabricated optical body.

[0108] In step S802, a ytterbium-doped fiber femtosecond laser with a wavelength of 1030 nm, a pulse width of 300 fs, and a repetition frequency of 500 kHz is used. The laser is focused into the interior of the prefabricated optical body through a high numerical aperture objective lens (NA=1.4). The laser focus trajectory is controlled by a three-dimensional displacement stage to scan and inscribe the waveguide structure point by point inside the prefabricated optical body.

[0109] Step S803: By adjusting the laser parameters in real time, the mode field confinement capability of the gradient waveguide gradually changes along the length direction.

[0110] Step S804: Anneal at 500°C for 2 hours.

[0111] Step S805: Deposit a metal reflective film and machine positioning holes. This quartz solution exhibits extremely low intrinsic material loss and extremely high thermal stability.

[0112] In one of the third exemplary embodiments, taking the fabrication of a PEI resin optic as an example, the following steps are included:

[0113] Step S901, resin formulation preparation. Polyetherimide (PEI) is mixed uniformly with 10-20 wt% silica microspheres and 5 wt% silane coupling agent in a high-speed mixer, and then melt-blended and granulated in a twin-screw extruder.

[0114] Step S902, precision injection molding. Injection molding is performed under the following process conditions: mold temperature 180°C, melt temperature 360°C, injection pressure 150MPa, and holding time 5 seconds.

[0115] Step S903, Graded-index fiber fabrication. Take a section of graded-index multimode fiber with a core diameter of 50 μm, and perform thermal tapering using a precision fiber tapering device to continuously reduce the fiber core diameter from 50 μm to approximately 10 μm.

[0116] Step S904, fiber embedding and fixing. UV-curable optical adhesive is applied to the V-groove 280, the graded optical fiber is placed in the V-groove, and the adhesive is cured by irradiation with a UV LED for 30 seconds.

[0117] Step S905, end face treatment. Excess fiber is removed using a diamond dicing tool, and then ground and polished until Ra < 10nm.

[0118] Step S906, reflective surface coating. Deposit a 10nm titanium (Ti) adhesion layer and a 100nm silver (Ag) reflective layer.

[0119] Step S907, Applying the stress buffer layer. Fill the stress buffer groove with silicone and cure at 80°C for 1 hour.

[0120] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0121] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0122] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0123] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An integrated optical coupling device for co-packaged optics, characterized in that, include: An integral optical body made of transparent optical material, the optical body having a light input end face, a light output end face, and a reflective surface; A beam expanding and collimating structure is disposed on the light input end face or reflective surface of the optical body to receive a first beam emitted from the optical chip coupling port and expand and collimate the first beam into a second beam. A gradient optical waveguide is disposed inside the optical body and has a starting end and an ending end. The starting end is connected to the second light beam, and the ending end extends to the light output end face. The cross-sectional dimensions of the gradient optical waveguide gradually decrease from the starting end to the ending end. A positioning structure is disposed on the optical body to achieve passive mechanical alignment between the optical body, the optical chip, and the external fiber array.

2. The integrated optical coupling device according to claim 1, characterized in that, The beam expanding and collimating structure is a microlens, which is disposed on the light input end face.

3. The integrated optical coupling device according to claim 2, characterized in that, The reflecting surface is a planar reflecting slope, which is disposed in the optical path between the microlens and the gradient waveguide, and is used to reflect the second beam to the starting end of the gradient waveguide.

4. The integrated optical coupling device according to claim 3, characterized in that, The beam waist of the beam after being expanded by the microlens is located at the end face of the starting end of the graded waveguide.

5. The integrated optical coupling device according to claim 1, characterized in that, The beam expanding and collimating structure is disposed on the reflecting surface, and the beam expanding and collimating structure and the reflecting surface are integrated into a parabolic reflecting surface. The coupling port of the optical chip is located at or near the focal point of the parabolic reflecting surface.

6. The integrated optical coupling device according to claim 1, characterized in that, The positioning structure includes: A right-angled positioning surface is provided on the contact surface between the optical body and the optical chip, and is used to cooperate with the corresponding positioning block on the optical chip to perform lateral and longitudinal positioning between the optical body and the optical chip; A positioning hole is provided on the contact surface between the optical body and the fiber array, and is used to cooperate with the guide pin of the fiber array to align the optical body with the fiber array.

7. The integrated optical coupling device according to claim 1, characterized in that, The optical body is also provided with a stress buffer structure, which is a flexible pad or groove disposed on the contact surface between the optical body and the optical chip, and is used to absorb the thermal stress between the optical chip and the optical body caused by temperature changes.

8. A co-packaged optical module, characterized in that, include: Switching chip; At least one silicon photonics chip is electrically interconnected with the switching chip, and the silicon photonics chip is provided with at least one coupling port; The integrated optical coupling device as described in any one of claims 1 to 7 is mounted above or to the side of the silicon photonic chip by passive alignment. The fiber optic array is inserted into the positioning hole of the integrated optical coupling device via guide pins.

9. A method for fabricating an integrated optical coupling device, applied to the integrated optical coupling device as described in any one of claims 1 to 7, characterized in that, The optical body is made of silicate material, and the method includes: Silicate materials are molded into prefabricated optical bodies with microlens structures and reflective surface prestructures through a molding process; An ion-exchange mask is deposited on the surface of the pre-fabricated optical body; A waveguide pattern is defined on the ion-exchange mask layer using a photolithography process. The waveguide pattern includes a start-end opening, an end-end opening, and a gradient section opening connecting the two. The waveguide core region is formed in the region corresponding to the waveguide pattern by an ion exchange process. The waveguide core region is subjected to secondary ion exchange treatment to form a buried graded refractive index waveguide; A reflective film is deposited on the pre-structured reflective surface; A positioning hole is formed on the optical body; The end face of the optical body is optically ground and polished.

10. A method for fabricating an integrated optical coupling device, applied to the integrated optical coupling device as described in any one of claims 1 to 7, characterized in that, The optical body is made of a modified resin, and the method includes: Modified resin is molded into an integral pre-fabricated optical body using an injection molding process; Graded fiber is fabricated by using a fiber taper process to gradually change the core diameter along the length direction; The graded optical fiber is placed into the groove of the pre-fabricated optical body and fixed. Remove excess optical fibers protruding from the groove and grind and polish the end face of the optical body; A reflective film is deposited on the reflective surface.

Images