Optical module packaging structure

Abstract

The invention provides an optical module packaging structure, which comprises an optical module, and the optical module comprises a ceramic base; the modulator chip is arranged on the ceramic base along a first direction; the laser array and the photoelectric detector array are arranged on the modulator chip in parallel along a second direction; wherein the laser array and the photoelectric detector array are respectively connected with the modulator chip through welding points in a face-down welding manner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic device packaging, and particularly relates to an optical module packaging structure. BACKGROUND

[0002] With the rapid development of cloud computing and artificial intelligence, high speed, miniaturization and low power consumption of optical modules have become core requirements. Traditional optical modules mostly adopt two-dimensional packaging mode, arranging lasers, modulators and detectors along the same plane. This arrangement mode leads to large module size, limiting the device integration density, and long optical path, which needs to be realized by micro-lens or long waveguide for optical coupling, easily introducing coupling loss. In addition, high-speed optoelectronic devices limit the modulation bandwidth and overall high-speed performance of the module due to parasitic capacitance, inductance and long signal transmission path in packaging.

[0003] To further improve the integration density and module performance, there is a trend of developing two-dimensional planar packaging to three-dimensional packaging, which can significantly shorten the optical path, improve the optical coupling efficiency and optimize the heat management by using vertical stacking and multi-layer interconnection technology. However, the existing technology still has bottlenecks in alignment accuracy, parasitic effect control, high-speed signal transmission and heat management, and has not formed a technical solution that can simultaneously solve high speed, high density, low loss and batch manufacturing. SUMMARY

[0004] In view of the above problems, the present application provides an optical module packaging structure, which comprises an optical module, and the optical module comprises: a ceramic base; a modulator chip arranged on the ceramic base along a first direction; a laser array and a photodetector array arranged side by side on the modulator chip along a second direction; wherein the laser array and the photodetector array are connected to the modulator chip through soldering points.

[0005] In the above scheme, the laser array comprises a vertical cavity surface emitting laser, and the emission surface of the laser array comprises a plurality of super surface structures.

[0006] In the above scheme, the laser array comprises a substrate layer, and a plurality of light emitting holes are arranged on the substrate layer, and a super surface structure is arranged in each light emitting hole.

[0007] In the above scheme, the modulator chip comprises a grating coupler, an input optical waveguide, a modulation region and an output optical waveguide; the light signal emitted by the laser array is injected vertically into the grating coupler of the input end of the modulator chip through photonic wire bonding.

[0008] In the above scheme, the emission surface of the laser array corresponds to the grating coupler, the light signal emitted by the laser array is integrated and emitted after being shaped by the plurality of super surface structures, and then enters the input optical waveguide of the modulator chip through the grating coupler.

[0009] In the scheme, the photodetector array includes a single row of carrier photodetectors, and the light signal emitted by the modulator chip is coupled by the grating coupler at the output end and then vertically injected into the photodetector array through the photonic wire bonding.

[0010] In the scheme, the incident surface of the photodetector array includes a plurality of super surface structures, and the grating coupler at the output end of the modulator chip corresponds to the incident surface of the photodetector array.

[0011] In the scheme, the laser array includes a first electrode and a second electrode, and the laser array and the modulator chip share the second electrode through the welding point.

[0012] In the scheme, the photodetector array includes a first electrode and a third electrode, and the photodetector array and the modulator chip share the third electrode through the welding point.

[0013] In the scheme, the ceramic base is a multilayer low-temperature co-fired ceramic, and an optical via hole is arranged in the ceramic base to realize multi-layer optical interconnection.

[0014] In the scheme, the optical module packaging structure further includes a packaging shell, and the packaging shell realizes the sealing and packaging of the optical module in a laser welding manner.

[0015] The technical scheme of the embodiment of the application has at least the following beneficial effects:

[0016] (1) The optical module packaging structure is provided with a super surface structure on the emitting surface of the laser array and the light-incident surface of the photodetector array, effectively suppresses the beam divergence, greatly improves the coupling efficiency of the grating coupler, and reduces the optical insertion loss. Compared with the traditional microlens scheme, the super surface structure has the advantages of planarization and easy large-scale preparation, and can significantly improve the stability and consistency of the optical interconnection link.

[0017] (2) The optical module packaging structure adopts a low-crosstalk high-speed electrical channel design, and uses a common electrode structure to simplify signal transmission. The laser array and the modulator chip share a ground electrode (G electrode), and the modulator chip and the photodetector array share a signal electrode (S electrode), which effectively reduces the number of electrodes, reduces the parasitic capacitance and inductance effect, and ensures the integrity of the signal in the high-speed transmission process. At the same time, this structure reduces the power consumption of the module, which is conducive to realizing higher modulation rate and lower bit error rate.

[0018] (3) Through flip-chip welding and 2.5-dimensional integration, the compact packaging of the laser array, the modulator chip and the photodetector array is realized. The structure avoids the delay and crosstalk introduced by long-distance wiring, significantly shortens the length of the optoelectronic interconnection link, and improves the mechanical reliability of the interconnection between devices. Unlike traditional planar optoelectronic integration, the packaging form of the present application takes into account miniaturization and high performance, and can adapt to the demand for higher density optoelectronic integration.

[0019] (4) The high-speed vertical cavity surface emitting laser single-carrier photodetector and lithium niobate modulator and other high-bandwidth optoelectronic devices are used in the optical module packaging structure, so that the optical module can withstand higher frequency signals in the process of optical-electric conversion and modulation, realizing high bandwidth and high speed of the whole system.

[0020] (5) The optical module packaging structure realizes high-bandwidth, low-power, miniaturized optical modules through the coordinated design of optical metasurfaces, common electrodes and three-dimensional packaging. It is not only suitable for high-speed optical interconnection and data center communication, but also can be extended to on-chip optical computing, sensing and optoelectronic integrated circuits and other application scenarios. While ensuring high speed and low power consumption, it has higher system integration and large-scale industrialization. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The structure diagram of the optical module packaging structure according to the embodiment of the present application is schematically shown.

[0022] Figure 2 The structure diagram of the laser array according to the embodiment of the present application is schematically shown.

[0023] Figure 3 The structure diagram of the metasurface structure according to the embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0025] Figure 1 The structure diagram of the optical module packaging structure according to the embodiment of the present application is schematically shown. Figure 2 The structure diagram of the laser array according to the embodiment of the present application is schematically shown. Figure 3 The structure diagram of the metasurface structure according to the embodiment of the present application is schematically shown.

[0026] As Figure 1As shown in the embodiment of the present application, a light module packaging structure is provided, comprising a light module, the light module comprising: a ceramic base 8; a modulator chip 5 arranged on the ceramic base 8 along a first direction X1; a laser array 2 and a photodetector array 7 arranged side by side on the modulator chip 5 along a second direction X2; wherein the laser array 2 and the photodetector array 7 are connected to the modulator chip 5 through solder joints 6 in a flip-chip manner.

[0027] Hereinafter, the light module packaging structure will be described in detail.

[0028] In the embodiment of the present application, the laser array 2 comprises a vertical-cavity surface-emitting laser (VCSEL), and the emission surface of the laser array 2 comprises a plurality of metasurface structures 3. It can be understood that the laser array 2 can be a vertical-cavity surface-emitting laser array, and the material used by the vertical-cavity surface-emitting laser array comprises, but is not limited to, gallium arsenide (GaAs), indium phosphide (InP), or gallium nitride (GaN), etc.

[0029] Specifically, please refer to Figure 2 and Figure 3 As shown in the embodiment of the present application, the laser array 2 comprises a substrate layer 21 and a multi-layer DBR mirror 22, and a plurality of light-emitting holes are arranged on the substrate layer, and each light-emitting hole is provided with a metasurface structure 3.

[0030] Exemplarily, the substrate layer 21 can be made of gallium arsenide (GaAs), indium phosphide (InP), or gallium nitride (GaN), etc.

[0031] For example, the VCSEL laser adopts a silicon-doped AlGaAs / GaAs multi-layer DBR mirror, the threshold current is about 1.2 mA, and the maximum output power is 3 mW. The substrate layer is made of gallium arsenide (GaAs), and the thickness thereof is 150 um, and the refractive index n1 thereof is 3.552.

[0032] Please refer to Figure 1 and Figure 2 It can be understood that, after the laser array 2 is connected to the modulator chip 5 through the solder joints 6 in a flip-chip manner, the metasurface structure 3 is located at the output emission surface of the laser array 2 (i.e., the side facing the modulator chip 5), and the light signal emitted by the laser is shaped and integrated to the output of the emission surface of the laser array 2.

[0033] For example, please refer to Figure 2 and Figure 3As shown, a super surface microstructure with a period of 500 nm is prepared on the emitting surface of the laser array 2 for beam shaping and divergence suppression. A layer of other material 20, such as silicon nitride Si3N4, silicon Si, silicon dioxide SiO2, etc. is first plated on the substrate layer; then, according to the phase value of each position (each point), the structure (such as radius, length-width, etc.) of each position is modified, and through FDTD simulation, the optimized super surface can reduce the beam divergence angle from the original 15° to about 3°.

[0034] It can be understood that for the high divergence angle beam emitted vertically by the laser array 2, the super surface structure 3 is used to realize the enhancement and shaping of the beam, and the high divergence angle beam is compressed to the mode matching range required by the grating coupler 4 or the waveguide in the modulator chip 5, and is directly coupled to the waveguide or the grating coupler.

[0035] In an embodiment of the present application, as shown in Figure 1 The modulator chip 5 is packaged on a ceramic base 8, and the modulator chip 5 includes a grating coupler 4, an input optical waveguide, a Mach-Zehnder modulator (MZM), a coplanar waveguide electrode structure, and an output optical waveguide. As shown in Figure 1 The grating coupler 4 is provided at the input end and the output end of the modulator chip 5. It should be noted that the grating coupler in this embodiment is also replaced by a free-form surface coupler.

[0036] Exemplarily, the material used by the modulator chip includes but is not limited to silicon or a ternary semiconductor or lithium niobate or lithium tantalate or lead zirconium titanate lead, etc.

[0037] Exemplarily, the grating coupler can be a surface grating coupler, a buried grating coupler, a double-layer / stacked grating coupler, or a photonic crystal grating coupler, to realize the vertical incidence and emission of light.

[0038] In an embodiment of the present application, the modulator chip 5 is aligned with the laser array 2 through the grating coupler 4 at the input end.

[0039] It can be understood that the emitting surface of the laser array 2 corresponds to the grating coupler 4, and the light signal emitted by the laser array 2 is integrated and emitted after being shaped by the multiple super surface structures 3, and then enters the input optical waveguide of the modulator chip 5 through the grating coupler 4.

[0040] Exemplarily, the light signal emitted by the laser array 2 is vertically injected into the grating coupler 4 at the input end of the modulator chip 5 through photonic wire bonding. By adjusting the cross-sectional size and gradient structure of the photonic wire, the light mode is naturally transitioned from the laser array to the grating coupler, and the mode mismatch loss is reduced.

[0041] Exemplarily, the light signal emitted by the laser array 2 can also be coupled by 3D printing optical micro-lenses and a free-form coupling device.

[0042] It can be understood that the laser array and the modulator chip are connected by flip-chip, the emitting surface of the laser array faces the grating coupler or the free-form coupling device on the modulator chip, and the light beam is shaped by the lens array or the micro-lenses to enter the waveguide of the modulator, thereby realizing high-density three-dimensional interconnection of optics and electricity.

[0043] In the embodiment of the present application, as shown in Figure 1 The laser array 2 includes a first electrode 1 and a second electrode 9; and the laser array 2 and the modulator chip 5 are connected by the soldering point 6 to share the second electrode 9.

[0044] Specifically, the laser array includes a plurality of electrodes, which can all be capacitive load electrodes for carrying high-speed signals. The first electrode 1 can also be a high-speed electrode, and the second electrode 9 can be a G electrode, which is a common electrode. The laser array and the modulator chip are connected by flip-chip, and the ground electrodes are shared by the soldering points. The G electrode common electrode design reduces parasitic capacitance and inductance, reduces crosstalk, and is suitable for high-speed modulation.

[0045] In the embodiment of the present application, the ceramic base 8 is a multilayer low-temperature co-fired ceramic, and an optical via is arranged in the ceramic base 8 to realize multi-layer optoelectronic interconnection. It can be understood that the ceramic base includes a plurality of metal interconnection circuits to realize distribution of electrical signals, RF interface and heat dissipation.

[0046] In the embodiment of the present application, as shown in Figure 1 The photodetector array 7 is connected to the modulator chip 5 by flip-chip through the soldering point 6.

[0047] Exemplarily, the photodetector array 7 includes, but is not limited to, a Uni-traveling carrier photodetector (UTC-PD), a MSM (Metal-Semiconductor-Metal) photodetector, a Ge-on-Si vertical incidence detector, etc. In the embodiment, no matter which detector is used, the light signal is vertically incident into the photodetector array 7.

[0048] As shown in Figure 1 In the embodiment of the present application, the incident surface of the photodetector array 7 includes a plurality of super surface structures 3; and the grating coupler 4 at the output end of the modulator chip 5 corresponds to the incident surface of the photodetector array 7.

[0049] It can be understood that the light emitted by the modulator chip is vertically incident on the photodetector array after passing through the grating coupler, and the light incident surface of the photodetector array also adopts the beam shaping super surface structure.

[0050] Further, the light signal emitted by the modulator chip 5 passes through the photonic wire bonding and is vertically injected into the photodetector array 7 after passing through the grating coupler 4 of the output end.

[0051] In the embodiment of the present application, the photodetector array 7 includes a first electrode 1 and a third electrode 10; the photodetector array 7 and the modulator chip 5 share the third electrode 10 through the soldering point 6.

[0052] Specifically, the photodetector array includes a plurality of electrodes, which can all be capacitive load electrodes for carrying high-speed signals. The first electrode 1 can also be a high-speed electrode, and the third electrode 10 can be an S electrode, which is a shared electrode. The photodetector array and the modulator chip adopt a flip-chip connection mode, and the shared electrode is realized through the soldering point.

[0053] Further, in the embodiment of the present application, as shown in Figure 1 The optical module packaging structure further includes a packaging shell, and the packaging shell realizes the sealing packaging of the optical module in a laser welding manner.

[0054] Specifically, based on the above, an optical module including a ceramic base 8, a modulator chip 5, a laser array 2, and a photodetector array 7 is obtained. The packaging shell is welded on the ceramic base 8 of the optical module in a laser welding manner to complete the sealing packaging, and the optical module packaging structure of the present embodiment is obtained. Exemplarily, the packaging shell can adopt a metal-ceramic hybrid shell, and a transparent window is provided at the top to facilitate the fiber array coupling or free-space optical path interface. In addition, the air-tightness and thermal management functions of the entire optical module packaging structure are also provided.

[0055] Further, in the embodiment of the present application, the optical module packaging structure further includes a radio frequency lead array, which is connected with the electrode of the modulator chip through a coplanar waveguide structure and is used for transmitting high-speed driving signals.

[0056] Exemplarily, the radio frequency lead array adopts a stripline or coplanar waveguide structure and has an impedance matching structure.

[0057] Based on the above optical module packaging structure, it can be understood that, as shown in Figure 1As shown, the laser array 2 containing high-speed vertical cavity surface emitting lasers is used as the light source, and its emitting surface is optimized by setting a metasurface structure 3 on the optical output end emitting surface. The metasurface structure controls the phase of the outgoing light field through nanoscale periodic microstructures, realizes beam divergence suppression and mode shaping, and thus improves the coupling efficiency with the modulator chip 5. The laser array 2 and the modulator chip 5 adopt a vertical coupling mode, and the modulator is located directly below the laser. The optical signal is injected into the grating coupler 4 of the input end of the modulator chip 5 through photonic wire bonding, realizing fast transmission of the optical signal. The electrode layout of the laser array 2 and the modulator chip 5 adopts a common ground electrode (G electrode) design, which not only reduces the number of electrodes but also reduces the parasitic capacitance effect and improves the high-speed modulation performance.

[0058] Further, as shown in Figure 1 The output end of the modulator chip 5 and the input end of the photodetector array 7 are arranged in a vertical coupling mode, and high-efficiency transmission of the optical signal is realized through photonic wire bonding. The photonic wire bonding process precisely aligns the output end of the modulator chip 5 and the input end of the photodetector array 7 at a micron-level precision, significantly reduces the coupling loss, and effectively suppresses the optical signal crosstalk. The modulator chip 5 and the photodetector array 7 share a signal electrode (S electrode), and through optimization of the circuit layout and high-speed channel design, independent transmission of multi-channel high-speed signals is realized, ensuring the overall bandwidth and signal integrity of the system.

[0059] Further, inside the optical module, the high-speed driving signal of the modulator chip 5 is transmitted to the modulation area through a common electrode and a microstrip line structure. The laser array 2, the modulator chip 5, and the photodetector array 7 are electrically connected to the ceramic base 8 through flip-chip bonding, taking into account heat dissipation and mechanical stability.

[0060] Further, the optical module package adopts a 2.5-dimensional or three-dimensional integration process, vertically stacking the laser, modulator, and detector on a high-thermal-conductivity ceramic base, and simultaneously realizing electrical connection with the PCB board through flip-chip bonding. The ceramic base provides an efficient heat dissipation channel, ensuring stable operation of high-speed devices under high power conditions.

[0061] Based on the above description of the optical module packaging structure, a specific embodiment is proposed below.

[0062] For example, a surface grating coupler is integrated at the incident end of a thin-film lithium niobate modulator chip. The coupler adopts a single-layer or double-layer grating structure, and by adjusting the etching depth (about 70-120 nm), period (about 630-680 nm), and duty cycle (40-60%), the incident light is efficiently coupled into the thin-film lithium niobate waveguide layer at an angle of about 10°. The light coupled into the waveguide gradually transitions to a thin-film lithium niobate-based ridge waveguide through a mode converter. A Mach-Zehnder modulator (MZM) is integrated in the waveguide region, and a differential electrode driving structure is adopted, with a 50 Ω matching bandwidth of more than 40 GHz. The electrodes are electrically connected to the external driving circuit through a coplanar waveguide wire bonding method. Due to the use of vertical optical coupling, the input and output ends of the modulator are located on the surface of the chip, eliminating the need for direct coupling of optical fibers to the sidewall of the chip, thereby avoiding high-precision polishing and alignment processes. The thin-film lithium niobate modulator chip adopts a LiNbO3 thin film with a thickness of about 300 nm, and the modulator Vπ is about 3V, with a modulation bandwidth of >50 GHz. The modulator is vertically aligned with a VCSEL laser array output end through photonic wire bonding.

[0063] Further, the VCSEL laser array, the thin-film lithium niobate modulator chip, and the single-row carrier photodetector (UTC-PD) array are all fixed through flip-chip bonding. The flip-chip bonding diameter is about 50 µm, the pitch is 150 µm, and the solder material is a lead-free SnAgCu alloy to ensure high reliability and good thermal conductivity. Flip-chip bonding not only achieves mechanical fixation of the device and the base, but also provides a low parasitic resistance and low parasitic inductance high-speed electrical connection channel. Through flip-chip bonding, the laser and the lithium niobate modulator share a ground electrode (G electrode), with an electrode length of about 1.5 mm and a design characteristic impedance of 50 Ω to match high-speed driving signals. The modulator and the UTC-PD share a signal electrode (S electrode), significantly shortening the electrical signal path, thereby reducing crosstalk and delay and ensuring high-speed signal integrity.

[0064] Further, the UTC-PD has a response bandwidth of >60 GHz, a dark current of <1 µA, and a photoelectric conversion efficiency of about 0.8 A / W. The detector is aligned with the modulator output end through photonic wire bonding, and the fiber coupling loss is ≤2 dB.

[0065] Further, to improve heat dissipation performance, the ceramic base uses Ferro-A6M material with a smaller loss tangent, and the ceramic substrate is based on low-temperature co-fired ceramic (LTCC) technology. Among the optional conductors Ag, Au, and PtPdAu, Au is selected as the inner and outer layer conductor of the ceramic substrate with a thickness of 10 um. The operating temperature of the laser and the modulator can be controlled below 45°C, and stable output is maintained at a high-speed modulation of 50 GHz.

[0066] Further, the whole optical module adopts a 2.5-dimensional packaging structure, the laser, the modulator and the detector are vertically stacked, the high-speed signal is led out to the PCB board through flip-chip soldering, the width of the microstrip line on the PCB is 0.2mm, the impedance matching is 50Ω, and bidirectional data transmission is supported. The module test result shows that, under 50Gbps NRZ modulation, the bit error rate is <10 -10 , the optical power loss is ≤2.5dB, and the requirement of high-speed data center optical interconnection application is met.

[0067] Through the embodiment of the application, a high-bandwidth, high-speed, low-light-loss, small-size and high-reliability optical module packaging is realized, meanwhile, the super surface enhancement and photon wire bonding technology are adopted, the optical coupling efficiency and electrical signal integrity are significantly improved, and the application scenarios of high-speed optical communication and on-chip optical integration are suitable.

[0068] The above specific embodiments further specifically describe the purpose, technical scheme and beneficial effects of the application, and it should be understood that the above is only a specific embodiment of the application and is not used to limit the application, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. An optical module package structure, characterized by, The optical module comprises: a ceramic base (8); a modulator chip (5) disposed on the ceramic base (8) along a first direction; a laser array (2) and a photodetector array (7) juxtaposed on the modulator chip (5) along a second direction; wherein the laser array (2) and the photodetector array (7) are connected to the modulator chip (5) through soldering points (6) in a flip-chip manner.

2. The optical module package structure according to claim 1, wherein, The laser array (2) comprises vertical cavity surface emitting lasers, and the emission surface of the laser array (2) comprises a plurality of super surface structures (3).

3. The optical module package structure according to claim 1, wherein, The laser array (2) comprises a substrate layer, and a plurality of light-emitting holes are arranged on the substrate layer, and each light-emitting hole is provided with a super surface structure (3).

4. The optical module package structure according to claim 1, wherein, The modulator chip (5) comprises a grating coupler (4), an input optical waveguide, a modulation region, and an output optical waveguide. The light signal emitted by the laser array (2) is vertically injected into the grating coupler (4) at the input end of the modulator chip (5) through photonic wire bonding.

5. The optical module package structure according to claim 2 or 4, wherein The emission surface of the laser array (2) corresponds to the grating coupler (4), and the light signal emitted by the laser array (2) is integrated into the emission surface after being shaped by a plurality of super surface structures (3) and then emitted, and then enters the input optical waveguide of the modulator chip (5) through the grating coupler (4).

6. The optical module package structure according to claim 1, wherein, The photodetector array (7) comprises a single-row carrier photodetector, and the light signal emitted by the modulator chip (5) is vertically injected into the photodetector array (7) through the grating coupler (4) at the output end after the light signal.

7. The optical module package structure according to claim 6, wherein The incident surface of the photodetector array (7) comprises a plurality of super surface structures (3). The grating coupler (4) at the output end of the modulator chip (5) corresponds to the incident surface of the photodetector array (7).

8. The optical module package structure according to claim 1, wherein, The laser array (2) comprises a first electrode (1) and a second electrode (9); The laser array (2) and the modulator chip (5) share the second electrode (9) through the soldering points (6).

9. The optical module package structure according to claim 1, wherein, The photodetector array (7) comprises a first electrode (1) and a third electrode (10); The photodetector array (7) and the modulator chip (5) share the third electrode (10) through the soldering points (6).

10. The optical module package structure according to claim 1, wherein, The ceramic base (8) is a multilayer low-temperature co-fired ceramic, and an optical via hole is arranged in the ceramic base (8) to realize multilayer optoelectronic interconnection.

11. The optical module package structure of claim 1, wherein, The optical module packaging structure further comprises a packaging shell, and the packaging shell realizes sealing and packaging of the optical module in a laser welding manner.

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