Laser Packaging Structure and Fabrication Method

Abstract

This invention discloses a laser packaging structure and its fabrication method. The packaging structure includes a substrate, a laser chip, a coupling conversion module, and a driving module. The laser chip and the coupling conversion module are sequentially mounted on the substrate. An encapsulation layer is disposed between the driving module and the substrate. The encapsulation layer at least partially covers the laser chip and the coupling conversion module. The driving module is electrically connected to the laser chip to drive the laser chip. An optical path channel is formed between the laser chip, the coupling conversion module, and the encapsulation layer. The coupling conversion module is used for optical coupling. According to the laser packaging structure and its fabrication method of this invention, by integrating the encapsulation layer and the optical path channel design, high-density packaging is achieved while ensuring optical path transmission stability. This effectively solves the problems of large size, poor reliability, and low heat dissipation efficiency of traditional packaging, and has the advantages of compact structure, high reliability, excellent heat dissipation performance, and effective improvement of optical coupling efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser package, and particularly relates to a laser package structure and a preparation method thereof. BACKGROUND

[0002] With the development of high-bandwidth applications such as optical communication, artificial intelligence and data center, optoelectronic devices are rapidly evolving towards high power, high integration, miniaturization and high reliability. Especially in the high-speed pluggable optical module and co-packaged optics (CPO) scenarios, higher requirements are put forward for the external laser source (ELS) package structure.

[0003] Figure 1 A traditional discrete scheme is shown, which is mainly based on the current mainstream external laser package process and flip-chip and metal wire bonding. The laser is welded on the heat dissipation substrate through flip-chip, and is interconnected with the driving chip through wire bonding. The coupling between the laser and the optical fiber depends on the active alignment structure such as lens and fine adjustment platform. Such structure has the following disadvantages: low yield: high alignment accuracy is required, and manual fine adjustment or active alignment equipment is needed; large package size: enough space is needed for optical path calibration and buffer; poor reliability: the wire bonding structure is easily affected by thermal mechanical stress, and the aging life is limited; long heat dissipation path and low efficiency: multi-stage heat conduction interfaces are stacked, resulting in high temperature rise and large thermal resistance; difficult to mass produce: limited by traditional packaging precision and process complexity.

[0004] In addition, there are edge coupling schemes and vertical coupling schemes, which are different from the discrete scheme. The edge coupling scheme introduces a waveguide horizontal coupling structure between the photonic integrated circuit (PIC) and the optical fiber, and is packaged by molding material to improve integration. Although the packaging heat path and precision control method are partially improved, there are still the following problems: the coupling efficiency is highly sensitive to the waveguide section precision; the molding material is usually not airtight structure, and there are water absorption and thermal expansion and contraction stress problems; the temperature is uncontrollable during the molding process, which is easy to cause stress or performance degradation to the laser.

[0005] The vertical coupling scheme (such as realizing near-vertical coupling between waveguides and optical fibers through grating couplers) has begun to attract attention, which can break through the space limitation of edge coupling and flexibly arrange the optical input / output (I / O) points. However, such scheme still lacks efficient integration with reliable packaging process, especially facing the following challenges: how to realize the light transmission packaging of optical path (maintain the coupling efficiency while improving the reliability); how to effectively seal while maintaining low-temperature process to avoid optical failure; how to integrate the heat dissipation structure and precision temperature control module to prevent laser performance drift.

[0006] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in any country in the world. SUMMARY

[0007] The present application aims to provide a laser package structure and a preparation method thereof, which can solve the problems of low coupling efficiency, non-airtight structure, uneven heat dissipation, unstable temperature, low integration level and high manufacturing complexity in the prior art.

[0008] To achieve the above object, a technical solution provided by one embodiment of the present application is as follows: a laser package structure, comprising: a substrate, a laser chip, a coupling conversion module and a driving module, the laser chip and the coupling conversion module are sequentially mounted on the substrate, a packaging layer is arranged between the driving module and the substrate, the packaging layer at least partially covers the laser chip and the coupling conversion module, the driving module is electrically connected with the laser chip to drive the laser chip, an optical path channel is formed between the laser chip, the coupling conversion module and the packaging layer, and the coupling conversion module is used for optical coupling.

[0009] In one or more embodiments of the present application, the coupling conversion module comprises a mode spot converter and a photonic chip integrated with a waveguide, and / or the coupling conversion module comprises a grating coupler.

[0010] In one or more embodiments of the present application, a coupling window is formed on the driving module, the coupling window vertically penetrates the driving module and the packaging layer covering the top of the coupling conversion module to vertically couple and match with the coupling conversion module; or

[0011] a coupling window is formed on the driving module, the coupling window vertically penetrates the driving module and the packaging layer covering the top of the coupling conversion module to vertically couple and match with the coupling conversion module, a lens is mounted on the driving module, the lens covers the coupling window, and a prism is mounted on the top of the lens; and / or

[0012] a glass waveguide is mounted on the substrate on one side of the coupling conversion module, and the glass waveguide and the coupling conversion module horizontally edge-couple based on evanescent wave coupling.

[0013] In one or more embodiments of the present application, metal traces connected with the laser chip are arranged on the substrate, and the driving module is connected with the metal traces through solder balls; and / or

[0014] A plurality of laser chips are arranged, and a heat insulation groove is arranged on the substrate between the laser chips.

[0015] In one or more embodiments of the present application, the laser chip is provided with a thermoelectric refrigeration piece connected with the heat sink.

[0016] In one or more embodiments of the present application, the coupling conversion module is provided with a reflective film layer at the bottom; and / or

[0017] The light path channel is filled with light-transmitting glue.

[0018] In one or more embodiments of the present application, the substrate is an aluminum nitride ceramic substrate.

[0019] The present application further discloses a preparation method of the laser package structure, comprising:

[0020] providing a substrate;

[0021] welding the laser chip and the coupling conversion module to the substrate, leaving a light path channel between the laser chip and the coupling conversion module;

[0022] mounting the driving module on the substrate;

[0023] injecting a filling material into the gap region between the driving module and the substrate, and after the filling is completed, low-temperature curing the filling material to form a package layer.

[0024] In one or more embodiments of the present application,

[0025] vertically opening the coupling window through the driving module and the package layer covering the top of the coupling conversion module; or

[0026] mounting a lens covering the coupling window, and mounting a prism on the top of the lens;

[0027] and / or

[0028] mounting a glass waveguide on the substrate at the side of the coupling conversion module to perform horizontal edge coupling based on evanescent wave coupling with the coupling conversion module.

[0029] In one or more embodiments of the present application,

[0030] selecting a filling material with a moisture absorption rate <0.2%, and low-temperature curing the filling material at a temperature not higher than 160°C; and / or

[0031] attaching the thermoelectric refrigeration piece to the laser chip, and connecting the thermoelectric refrigeration piece with the external heat sink; and / or

[0032] providing an aluminum nitride ceramic substrate, and the thermal conductivity of the aluminum nitride ceramic substrate is greater than 170 W / m·K, and the thermal expansion coefficient is 4.2~5.4×10 -6 / K; and / or

[0033] Fill the light path channel with light transmission glue.

[0034] Compared with the prior art, the laser package structure and the preparation method thereof have the advantages of compact structure, high reliability, excellent heat dissipation performance and the ability to effectively improve the optical coupling efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 The circuit schematic diagram of the laser package structure in the prior art.

[0037] Figure 2 The first structure schematic diagram of the laser package structure in an embodiment of the present application.

[0038] Figure 3 (a) in the above is a front view of the metal wiring arrangement of the laser package structure in an embodiment of the present application.

[0039] Figure 3 (b) in the above is a top view of the metal wiring arrangement of the laser package structure in an embodiment of the present application.

[0040] Figure 3 (c) in the above is a side view of the metal wiring arrangement of the laser package structure in an embodiment of the present application.

[0041] Figure 4 The second structure schematic diagram of the laser package structure in an embodiment of the present application.

[0042] Figure 5 The structure schematic diagram of the laser package structure in another embodiment of the present application.

[0043] Figure 6 The first partial structure schematic diagram of the laser package structure in an embodiment of the present application.

[0044] Figure 7 The second partial structure schematic diagram of the laser package structure in an embodiment of the present application.

[0045] Figure 8A third partial structure diagram of the laser package structure in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to enable persons skilled in the art to better understand the technical solutions in the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in combination with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor should fall within the protection scope of the present disclosure.

[0047] In the specification, “coupling” or “connection” or “connection” includes both direct connection and indirect connection. Indirect connection is connection through an intermediate medium, such as connection through an electrically conductive medium, which can have parasitic inductance or parasitic capacitance; indirect connection can also include connection through other active devices or passive devices on the basis of achieving the same or similar functional purposes, such as connection through circuits or components such as switches, follower circuits, etc. In addition, in the invention, words such as “first”, “second”, etc. are mainly used to distinguish one technical feature from another technical feature, and do not necessarily require or imply a certain actual relationship, quantity or order between the technical features.

[0048] In the detailed description of the specification, reference is made to the drawings forming a part thereof, in which like numerals refer to like parts throughout and in which the example embodiments can be illustrated by way of example. It should be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be taken as limiting.

[0049] Various operations in the specification can be described in sequential order. However, the order of the description should not be interpreted as implying a sequential relatedness of the operations. Specifically, the operations can not be performed in the order presented. The described operations can be performed in a different order than described. Various additional operations can be performed and / or described operations can be omitted in additional embodiments.

[0050] For the purposes of the present disclosure, the phrase “A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0051] Various components and devices may be referred to or shown in the singular (e.g., “transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0052] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used with respect to embodiments of this disclosure are synonymous.

[0053] like Figure 2 As shown, a laser packaging structure in one embodiment of the present invention includes: a substrate 1, a laser chip 2, a coupling conversion module 3, and a driving module 4.

[0054] Laser chip 2 and coupling conversion module 3 are sequentially mounted on substrate 1. A packaging layer 5 is provided between driving module 4 and substrate 1. The packaging layer 5 at least partially covers laser chip 2 and coupling conversion module 3. Driving module 4 is electrically connected to laser chip 2 to drive laser chip 2. An optical path channel 6 is formed between laser chip 2, coupling conversion module 3 and packaging layer 5. Coupling conversion module 3 is used for optical coupling.

[0055] In one embodiment, substrate 1 is an aluminum nitride ceramic substrate, which serves as the load-bearing and heat-conducting platform for the entire packaging structure. Its thermal conductivity is greater than 170 W / m·K, and its coefficient of thermal expansion is 4.2~5.4×10⁻⁶. -6 / K, the aluminum nitride ceramic substrate creates a direct heat dissipation path from the laser chip 2 to the external environment through its high thermal conductivity. At the same time, its coefficient of thermal expansion matches that of semiconductor materials such as indium phosphide (InP), which can reduce interfacial thermal stress.

[0056] Laser chip 2 is an optical element that generates laser light, such as an indium phosphide (InP)-based distributed feedback (DFB) laser. It is fixed on substrate 1 by flip-chip bonding to shorten the electrical connection distance with drive module 4. The electrode thickness of laser chip 2 is 200nm ± 20nm, and the solder thickness between laser chip 2 and substrate 1 is controlled at 6μm ± 2μm.

[0057] like Figure 2 and Figure 3As shown, the substrate 1 is provided with metal tracks 11 connected with the laser chip 2, and the driving module 4 is connected with the metal tracks 11 through solder balls 41, which is used to control the driving current of the laser and the communication of the whole system. The electronic integrated chip EIC in the driving module 4 is connected with the metal tracks 11 on the substrate 1 through the solder balls 41, replacing the traditional wire bonding interconnection and eliminating the risk of thermal mechanical stress of the wire bonding structure. The substrate 1 is provided with through holes 12 for passing wires connected with the metal tracks 11. The number of the metal tracks 11 can be selected as needed, and each metal track 11 corresponds to a through hole 12.

[0058] As shown in the figure, Figure 2 The driving module 4 includes a bottom metallization layer UBM connected with the solder balls 41, a redistribution layer RDL soldered on the bottom metallization layer UBM, an electronic integrated chip EIC soldered on the redistribution layer RDL, and a PCB board above the electronic integrated chip EIC. The redistribution layer RDL, the electronic integrated chip EIC and the PCB board are filled with a solid encapsulation material EMC (the solid encapsulation material EMC is based on epoxy resin, filled with inorganic fillers such as silica, and modified with curing agent, coupling agent, etc.).

[0059] As shown in the figure, Figure 4 The electronic integrated chip in the driving module 4 can be provided with two, EIC1 and EIC2, and the corresponding solder balls are 411 and 412. In addition, the number of metal tracks, through holes and the like are also set accordingly.

[0060] The packaging layer 5 is filled with low-temperature curing material between the driving module 4, the substrate 1, the laser chip 2 and the coupling conversion module 3, forming a packaging area with excellent mechanical stability and air tightness. The low-temperature curing material has the characteristics of low water absorption and low thermal expansion coefficient (CTE: Coefficient of Thermal Expansion), effectively preventing the thermal failure and damp aging of the laser chip 2. The packaging layer 5 at least partially covers the laser chip 2 and the coupling conversion module 3, and retains the light path channel 6. The light path channel 6 is the light transmission space between the laser chip 2 and the coupling conversion module 3.

[0061] In an embodiment, inorganic filler particles (such as SiO2, AlN, glass powder) are filled in the low-temperature curing material to form a "physical barrier". When the particle size is larger than the gap, it will form a stacking effect in front of the gap, preventing further flow; or by controlling the temperature and the composition of the low-temperature curing material, when the viscosity is high, the filling process will occur Capillary Stop Valve in the small gap, not easy to penetrate into the reserved gap; or by filling the light transmission glue, the light path transmission can be ensured, the light loss is reduced and the coupling efficiency is maintained.

[0062] In this way, the flow area of the low-temperature curing material only covers the non-optical area and does not climb into the fine optical path channel 6, and the reserved optical path channel 6 can be filled and controlled with high precision.

[0063] In an embodiment, the coupling conversion module 3 includes a grating coupler, a mode spot converter, and a photonic chip integrated with a waveguide, which are used to couple the light output by the laser chip 2 to an external optical fiber or waveguide. The mode spot converter and the photonic chip integrated with the waveguide can realize horizontal coupling, and the grating coupler is integrated in the waveguide and can realize phase matching coupling with a vertical optical fiber.

[0064] By pasting the laser chip 2 and the coupling conversion module 3 in sequence on the high-precision heat dissipation substrate 1, and taking the horizontal plane of the substrate 1 as the vertical reference, the height position of the optical element is effectively fixed, the influence of vertical deviation on coupling performance is reduced, and the overall coupling efficiency and assembly process window are greatly improved.

[0065] After the laser chip 2 and the optical path channel 6 are packaged by the underfill method, horizontal coupling or vertical coupling can be flexibly used.

[0066] As shown in Figure 2 The driving module 4 is provided with a coupling window 7, the coupling window 7 vertically penetrates the driving module 4 and a packaging layer 5 covering the top of the coupling conversion module 3 to match the vertical coupling of the coupling conversion module 3, a lens 8 is installed on the driving module 4, the lens 8 covers the coupling window 7, and a prism 9 is installed on the top of the lens 8.

[0067] The coupling window 7 is used to provide a vertical transmission path for the optical signal without obstruction. The lens 8 is used to collimate or focus the divergent light beam. The prism 9 is used to adjust the direction of the optical path to match the coupling angle of the external optical fiber. The grating coupler can effectively convert the transverse mode in the waveguide into a nearly vertical outgoing mode, which is suitable for the optical fiber array led out through the top of the package.

[0068] The coupling window 7 vertically penetrates the driving module 4 and the packaging layer 5, so that the optical signal can directly penetrate the packaging layer 5 without multiple reflections or refractions, avoiding the optical path deviation or attenuation caused by the coverage of the packaging material in the traditional vertical coupling.

[0069] Compared with the edge coupling method, the vertical coupling has the following advantages: supporting flexible distribution of I / O positions, not limited by the edge of the waveguide; avoiding alignment errors of the cutting surface, suitable for array packaging; and being conducive to reducing the size of the module and realizing multi-channel integration.

[0070] As shown in Figure 2As shown, in an embodiment, a thermoelectric cooling piece 10 is arranged on the laser chip 2 and connected with a heat sink, the thermoelectric cooling piece 10 is integrated on the laser chip 2 to realize precise temperature control of the laser chip 2. The thermoelectric cooling piece 10 refers to a semiconductor device based on Peltier effect, which realizes bidirectional temperature control function through current direction switching and actively performs heat absorption or heat release operation when the temperature of the laser chip 2 is abnormal. The heat sink forms a heat conduction path by connecting with the thermoelectric cooling piece 10 to conduct excess heat.

[0071] Different from the discrete scheme, the present application can be based on 2.5D or 3D packaging technology, compact and efficient integrated thermoelectric cooling piece 10, which can accurately control the temperature of the laser chip 2 and the light path channel 6, and suppress the problems of wavelength drift and efficiency decline caused by temperature drift.

[0072] The thermoelectric cooling piece 10 is designed through the combination with the aluminum nitride ceramic substrate to realize efficient local heat control while keeping the structure compact.

[0073] As shown in Figure 3 and Figure 2 When multiple laser chips 2 are integrated on the same substrate 1, the laser chips 2 will generate local high heat flux during operation. If there is no thermal barrier structure between the channels, heat can be conducted laterally through the substrate 1, causing thermal crosstalk and further leading to problems such as temperature control device operation error, laser wavelength drift, and power inconsistency. Therefore, a heat insulation groove 13 can be precisely etched on the substrate 1 between the laser chips 2 to form a physical section or isolation band of heat flow, which can effectively block lateral heat conduction.

[0074] As shown in Figure 2 In an embodiment, a reflective film layer 31 is arranged at the bottom of the coupling conversion module 3 to improve the reflectivity of the coupling conversion module 3.

[0075] As shown in Figure 5 In other embodiments, the packaging layer 5 only covers part of the coupling conversion module 3, and a glass waveguide 20 is installed on the substrate 1 on one side of the covered coupling conversion module 3. The glass waveguide 20 and the coupling conversion module 3 perform horizontal edge coupling based on evanescent wave coupling. Evanescent wave coupling is a near-field coupling mechanism, that is, two waveguides are brought close within a very short distance (usually tens to hundreds of nanometers), so that the tail of the light field (evanescent field) of one waveguide penetrates into the other waveguide, thereby realizing energy transfer. Light does not need to pass through the lens 8 or microcollimator, avoiding complex processes such as optical film / lens, microalignment, etc. All input / output channels are kept in the plane (in-plane), which is convenient for fiber array side insertion type butt joint. The glass waveguide 20 realizes horizontal edge coupling with the mode spot converter through the evanescent wave coupling mechanism, reducing the sensitivity to waveguide end face processing precision.

[0076] This invention also discloses a method for fabricating a laser packaging structure, comprising:

[0077] like Figure 6 As shown, a substrate 1 is provided. In one embodiment, an aluminum nitride ceramic substrate is selected, and the aluminum nitride ceramic substrate has a thermal conductivity greater than 170 W / m·K and a coefficient of thermal expansion of 4.2~5.4×10⁻⁶. -6 / K is surface-metallized to form the welding electrode and interconnect metal trace 11 region. If a thermal insulation trench is required, it can be prepared by inductively coupled plasma etching (ICP), reactive ion etching (RIE), or laser etching (UV or IR).

[0078] like Figure 6 As shown, a reflective film layer 31 is generated at the bottom of the coupling conversion module 3. In one embodiment, to improve the grating coupling efficiency, a reflective film layer 31 is prepared on the lower surface of the coupling conversion module 3. A highly reflective metal (such as gold or copper) can be prepared on the surface area to form a mirror structure. It can be deposited by means of evaporation, sputtering or electroplating, and the film thickness depends on factors such as skin depth (the penetration depth of electromagnetic waves attenuated to 1 / e in metal) and thermal / mechanical compatibility requirements. Preferably, the film thickness is in the range of 100~300 nm. For 1550 nm wavelength laser, nearly 98.81% of the light can be reflected back to the grating coupler. Furthermore, in order to improve the reflectivity, a λ / 4 SiO2 film layer can be generated on the lower surface of the grating coupler, and the reflectivity can be increased to 99.5%.

[0079] The laser chip 2 and the coupling conversion module 3 with a reflective film layer 31 are soldered onto the substrate 1, leaving an optical path channel 6 between the laser chip 2 and the coupling conversion module 3. In one embodiment, a high-precision mounting device is used to flip-chip solder an aluminum nitride ceramic substrate onto an aluminum nitride ceramic substrate. Indium-based solder, such as In80Pb15Ag5, can be selected. A 1-5 μm gap is left between the laser chip 2 and the coupling conversion module 3, or the gap is filled with an optically transparent, heat-resistant, and light-transmitting adhesive to form the optical path channel 6. The light-transmitting adhesive filling the optical path channel 6 not only seals and protects the optical path but also reduces interface reflection loss during light transmission through refractive index matching.

[0080] The driving module 4 is mounted on the substrate 1. In one embodiment, an aluminum nitride ceramic substrate on which the laser chip 2 and the coupling conversion module 3 are mounted is flip-chip mounted onto the driving module 4 which integrates an electronic integrated chip (EIC). The electronic integrated chip (EIC) is connected to the metal traces 11 on the substrate 1 through solder balls. The diameter of the solder balls (Ball Grid Array) can be selected from 300 to 500 μm.

[0081] like Figure 7 As shown, a filler material is injected into the gap area between the driving module 4 and the substrate 1. After filling, the filler material is cured at low temperature to form the encapsulation layer 5. In one embodiment, a dispensing device is used to inject the filler material into the gap area between the driving module 4 and the substrate 1, the laser chip 2, and the coupling conversion module 3. After all filling is completed, the filler material is cured at a temperature not exceeding 160°C, and the curing time is controlled within 30 minutes (stage curing is possible: pre-curing + full curing). The moisture absorption rate of the filler material is <0.2% to prevent moisture expansion, corrosion of the laser, or induced failure. The coefficient of thermal expansion (CTE) of the filler material should be close to that of indium phosphide (InP) or aluminum nitride (AlN) to avoid chip warping or cracking caused by thermal expansion and contraction stress. By using a low moisture absorption filler material in conjunction with a low-temperature curing process, the encapsulation layer 5 will not undergo volume changes due to water absorption during the curing process, while also avoiding damage to the laser chip caused by high-temperature thermal stress.

[0082] In addition, to improve the adhesion of the filler material, surface plasma cleaning can be performed after flip-chipping the aluminum nitride ceramic substrate with the laser chip 2 and the coupling conversion module 3 onto the drive module 4 which integrates the electronic integrated chip EIC.

[0083] In a preferred embodiment, to avoid the difference in thermal expansion and contraction properties between the laser chip 2 and the filling material, a high-viscosity barrier structure can be pre-applied around the laser chip 2 to prevent the filling material from encapsulating the laser chip 2. The barrier structure material is preferably a non-flowing epoxy or gel-based adhesive.

[0084] like Figure 8 As shown, a coupling window 7 is formed by vertically opening through the driving module 4 and the encapsulation layer 5 covering the top of the coupling conversion module 3. In one embodiment, laser or plasma etching is performed at the encapsulation layer 5 and the driving module 4 perpendicular to the top of the coupling conversion module 3 to form the coupling window 7, maintaining the verticality of the coupling window 7 and the alignment accuracy with the grating coupler.

[0085] like Figure 2 As shown, a lens 8 is installed to cover the coupling window 7, and a prism 9 is installed on top of the lens 8 to improve coupling efficiency.

[0086] In addition, the thermoelectric cooling piece 10 is integrated and attached to the upper surface of the laser chip 2, and the hot spot cooling piece is connected with an external heat sink to improve the heat management efficiency. The heat sink can be embedded in the plastic package structure outside the package. The thermoelectric cooling piece 10 forms an active heat dissipation system by connecting with the external heat sink, and cooperates with the heat dissipation capacity of the high-thermal-conductivity aluminum nitride substrate to effectively control the working temperature of the laser chip 2.

[0087] Through simulation and experimental tests, it is shown that the packaging scheme is significantly better than the traditional scheme in the following performance indicators:

[0088] 1. The optical coupling efficiency is improved: the matching degree of the vertical coupling structure is improved by more than 20%.

[0089] 2. The thermal stability is improved: the temperature rise of the laser chip 2 is reduced by 4-10℃.

[0090] 3. The airtight reliability is improved: after 1000 hours of damp heat aging, the output power retention rate of the laser chip 2 is >95%.

[0091] In other embodiments, as shown in Figure 5 the coupling window 7 is not opened, the lens 8 and the prism 9 are not installed, the projection of the driving module 4 in the vertical direction only covers part of the coupling conversion module 3, and the packaging layer 5 also only covers part of the coupling conversion module 3. The glass waveguide 20 is installed on the substrate 1 on the side of the coupling conversion module 3 which is not covered by the packaging layer 5 to perform horizontal edge coupling with the coupling conversion module 3 based on evanescent wave coupling.

[0092] It is obvious to those skilled in the art that the present disclosure is not limited to the details of the above exemplary embodiments, and the present disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of the present disclosure. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present disclosure is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and scope of the equivalent elements of the claims. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0093] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A laser package structure, characterized by, The laser package structure comprises a substrate, a laser chip, a coupling conversion module and a driving module, the laser chip and the coupling conversion module are sequentially mounted on the substrate, a packaging layer is arranged between the driving module and the substrate, the packaging layer at least partially covers the laser chip and the coupling conversion module, the driving module is electrically connected with the laser chip to drive the laser chip, an optical path channel is formed between the laser chip, the coupling conversion module and the packaging layer, the coupling conversion module is used for optical coupling, a coupling window is formed on the driving module, the coupling window vertically penetrates the driving module and the packaging layer covering the top of the coupling conversion module to vertically couple and match the coupling conversion module, metal traces connected with the laser chip are arranged on the substrate, and the driving module is connected with the metal traces through solder balls; the driving module comprises a bottom metallization layer arranged at the bottom and connected with the solder balls, a redistribution layer welded on the bottom metallization layer, an electronic integrated chip welded on the redistribution layer and a PCB board located above the electronic integrated chip, and solid-state encapsulating material is filled between the redistribution layer, the electronic integrated chip and the PCB board. The coupling conversion module comprises a mode spot converter and a photonic chip integrated with a waveguide, and / or the coupling conversion module comprises a grating coupler.

2. The laser package structure of claim 1, wherein, A lens is mounted on the driving module, the lens covers the coupling window, and a prism is mounted on the top of the lens.

3. The laser package structure of claim 1, wherein, A plurality of laser chips are arranged, and heat insulation grooves are arranged on the substrate between the laser chips.

4. The laser package structure of claim 1, wherein, A thermoelectric refrigeration piece connected with a heat sink is arranged on the laser chip.

5. The laser package structure of claim 1, wherein, The coupling conversion module is provided with a reflective film layer at the bottom; and / or 6. The laser package structure of claim 1, wherein, The optical path channel is filled with light-transmitting glue. The substrate is an aluminum nitride ceramic substrate.

7. The laser package structure of claim 1, wherein, The preparation method of the laser package structure according to any one of claims 1-7 comprises:

8. A method for fabricating a laser packaging structure, characterized in that, providing a substrate; welding a laser chip and a coupling conversion module on the substrate, and leaving an optical path channel between the laser chip and the coupling conversion module; arranging metal traces connected with the laser chip on the substrate; mounting a driving module on the substrate, and connecting the driving module with the metal traces through solder balls; injecting filling material into the gap area between the driving module and the substrate, and after the filling is completed, low-temperature solidification of the filling material forms a packaging layer; vertically forming a coupling window penetrating the driving module and the packaging layer covering the top of the coupling conversion module; the driving module comprises a bottom metallization layer arranged at the bottom and connected with the solder balls, a redistribution layer welded on the bottom metallization layer, an electronic integrated chip welded on the redistribution layer and a PCB board located above the electronic integrated chip, and solid-state encapsulating material is filled between the redistribution layer, the electronic integrated chip and the PCB board. mounting a lens covering the coupling window, and mounting a prism on the top of the lens.

9. The method of claim 8, wherein the method further comprises:

10. The preparation method of the laser package structure according to claim 8, wherein a filling material with a moisture absorption rate <0.2% is selected, and the filling material is low-temperature solidified at a temperature not higher than 160°C; and / or a thermoelectric refrigeration piece is attached to the laser chip, and the thermoelectric refrigeration piece is connected with an external heat sink; and / or ​ Provided is an aluminum nitride ceramic substrate, and the thermal conductivity of the aluminum nitride ceramic substrate is greater than 170 W / m·K, the coefficient of thermal expansion is 4.2~5.4×10 -6 / K; and / or The light path channel is filled with light-transmitting glue.

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