Transceiving integrated optical chip and optical module

Abstract

The utility model relates to the technical field of optical communication, and provides a transceiving integrated optical chip, which comprises an optical detector chip and a laser chip, the laser chip and the optical detector chip are laminated, and the laser chip is integrated on the top surface of the optical detector chip. The utility model further provides an optical module which comprises the transceiving integrated chip, and the bottom surface of the optical detector chip is electrically connected to a PCB (printed circuit board). According to the BOSA optical module, the laser chip is integrated on the optical detector chip, the BOSA optical module is different from two independent optical devices in a traditional single-fiber bidirectional transceiving scheme, and the overall size of the optical devices is greatly reduced by the high-integration design scheme, so that the size of the whole BOSA optical module is reduced, and the development of miniaturization of a single BOSA optical module is facilitated.

Description

Technical Field

[0001] The utility model relates to the technical field of optical communications, in particular to a transceiver integrated optical chip and an optical module. Background Art

[0002] With the rapid development of communications technology, particularly driven by broadband access and 5G network construction, fiber-optic communications have become an indispensable component of modern communications networks due to their advantages such as high bandwidth, low loss, and resistance to electromagnetic interference. As the bridge connecting user terminals and the core network, the access network's transmission efficiency and resource utilization directly impact the performance of the entire communications system. The application of single-fiber bidirectional (BiDi) communication technology in optical communications has greatly improved fiber resource utilization and reduced construction costs, making it a research hotspot in the current communications field.

[0003] In traditional single-fiber bidirectional BOSA optical modules, there are generally two independent optical devices. For example, one optical device transmits a 1310nm optical signal, while the other optical device receives a 1550nm optical signal. In the BOSA optical module on the other end, one optical device transmits a 1550nm optical signal, while the other optical device receives a 1310nm optical signal. However, the size of this optical module with two independent optical devices is large, which is not conducive to the miniaturization of a single BOSA optical module. In addition, the traditional solution uses a beam splitter to separate or merge optical signals of different wavelengths. The beam splitter is an optical component made of quartz glass. Its light source irradiation surface is coated with an anti-reflection film, and the detector receiving surface is coated with a reflective film to ensure efficient transmission and reception of optical signals. However, these processing methods make the optical path more complicated and also increase costs. Utility Model Content

[0004] The purpose of the present invention is to provide a transceiver integrated optical chip and an optical module, which can at least solve some of the defects in the prior art.

[0005] To achieve the above objectives, an embodiment of the present invention provides the following technical solution: a transceiver integrated optical chip, comprising a photodetector chip and a laser chip, wherein the laser chip and the photodetector chip are stacked, and the laser chip is integrated on the top surface of the photodetector chip.

[0006] Furthermore, the quantum well layer of the laser chip is arranged in parallel with the light absorption layer of the photodetector chip.

[0007] Furthermore, a PN electrode is provided on the top surface of the laser chip.

[0008] Furthermore, a P-side electrode is provided on the top surface of the photodetector chip, and an N-side electrode is provided on the bottom surface of the photodetector chip.

[0009] Furthermore, the light-emitting cavity surface of the photodetector chip and the light-receiving cavity surface of the laser chip are on the same side and flush with each other.

[0010] Furthermore, the projected area of ​​the photodetector chip on the horizontal plane is larger than the projected area of ​​the laser chip on the horizontal plane.

[0011] Furthermore, an electrical isolation trench is provided on the top surface of the photodetector chip, and the electrical isolation trench at least encloses an LD chip area, and the laser chip is integrated in the LD chip area.

[0012] An embodiment of the present utility model provides another technical solution: an optical module, comprising the above-mentioned transceiver integrated chip, wherein the bottom surface of the optical detector chip is electrically connected to the PCB board.

[0013] Furthermore, a first filtering structure is provided on the emission light path of the laser chip, and a second filtering structure is provided on the receiving light path of the photodetector chip, and the refractive indexes of the first filtering structure and the second filtering structure are different.

[0014] Furthermore, a collimating lens is provided on the emission light path of the laser chip, and a converging lens is provided on the receiving light path of the photodetector chip. The collimating lens is located between the laser chip and the first filtering structure, and the converging lens is located between the photodetector chip and the second filtering structure.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. The laser chip is integrated on the photodetector chip. Different from the two independent optical devices in the traditional single-fiber bidirectional transceiver solution, the highly integrated design greatly reduces the overall size of the optical device, thereby reducing the volume of the entire BOSA optical module, which is conducive to the miniaturization of a single BOSA optical module.

[0017] 2. The projected area of ​​the photodetector chip on the horizontal plane is designed to be larger than the projected area of ​​the laser chip on the horizontal plane. On the one hand, the light absorption layer of the planar waveguide structure photodetector chip has a larger cross-sectional area and a thinner thickness than the light absorption layer of the traditional vertical incidence photodetector, which can absorb more photons and make electrons and holes reach the N-region and P-region faster, thereby improving the responsiveness of the photodetector chip. On the other hand, taking advantage of the fact that the photodetector chip itself generates less heat, the laser chip is integrated on the photodetector. The large-area planar waveguide photodetector chip can be used as a heat dissipation substrate for the laser chip, thereby improving the electro-optical conversion efficiency of the laser chip, enhancing the light output performance of the laser chip, reducing the operating current at the same power compared to the previous traditional solution, and greatly reducing the overall power consumption of the optical module.

[0018] 3. The light output cavity surface of the photodetector chip and the light output cavity surface of the laser chip are on the same side and flush, with controllable size and position, and almost no mechanical error, which greatly facilitates subsequent optical path coupling.

[0019] 4. Using filter structures with different refractive indices for optical path design can realize the function of single-fiber bidirectional communication and ensure that the transmitted light and the received light do not interfere with each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of a single-fiber bidirectional light transmitting and receiving circuit of an optical module provided in an embodiment of the present utility model;

[0021] Figure 2 A schematic diagram showing a top view of a transceiver integrated optical chip and external bonding wires provided in an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the light-emitting cavity surface and the light-receiving cavity surface of a transceiver integrated optical chip provided in an embodiment of the present utility model;

[0023] In the figure marks: 1-laser chip; 2-photodetector chip; 3-quantum well layer; 4-light absorption layer; 5-bracket; 6-collimating lens; 7-converging lens; 8-first filtering structure; 9-second filtering structure; 10-optical fiber; 11-transmitted light path; 12-received light path; 13-PCB board; 14-TIAVCC metal electrode; 15-current injection electrode; 16-GND electrode; 17-LD-N bonding area; 18-LD-P bonding area; 19-N electrode; 20-P electrode; 21-ridge; 22-PD-P bonding area; 23-electrical isolation channel; 24-N-surface electrode. DETAILED DESCRIPTION

[0024] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] See also Figures 1 to 3The present invention provides a method for preparing an integrated transceiver optical chip, comprising the following steps: fabricating a photodetector chip 2; during or after fabrication of the photodetector chip 2, integrating a laser chip 1 onto the photodetector chip 2, such that the laser chip 1 and the photodetector chip 2 are stacked; and fabricating the PN electrodes of the laser chip 1 and the photodetector chip 2, thereby obtaining the transceiver integrated chip. In this embodiment, the integration of the laser chip 1 onto the photodetector chip 2 significantly reduces the overall size of the optical components, thereby reducing the volume of the entire BOSA optical module, unlike conventional single-fiber bidirectional transceiver solutions that utilize two independent optical components. This highly integrated design significantly reduces the overall size of the optical components, thereby reducing the volume of the entire BOSA optical module and facilitating the miniaturization of individual BOSA optical modules. Specifically, conventional single-fiber bidirectional solutions utilize two independent optical components, each disposed separately, such as front-to-back or left-to-right on a PCB board 13. Regardless of the separation, this requires designing the optical paths of the optical transmitter and receiver components, resulting in more complex components and relatively cumbersome coupling. Overall, regardless of the design approach, the optical module cannot be very small. This embodiment cleverly integrates the laser chip 1 on the photodetector chip 2, which can reduce the space occupied by independent components and greatly reduce the product volume. After the integration is completed, the PN electrode is produced to obtain the transceiver integrated optical chip. In addition, this embodiment provides two different integration schemes. One is to integrate the laser chip 1 on the photodetector chip 2 during the production process of the photodetector chip 2, and then complete the production of the photodetector chip 2 and the laser chip 1 together. The other is to produce the laser chip 1 on the photodetector chip 2 after the photodetector chip 2 is produced. Both production methods can realize the optical transceiver function, but it is necessary to ensure that the laser chip 1 and the photodetector chip 2 are both stacked. The specific details of the two different implementation methods are detailed below.

[0026] See also Figure 1 、 Figure 2 and Figure 3During the fabrication of the photodetector chip 2, the laser chip 1 is integrated onto the photodetector chip 2. Specifically, the process includes: first fabricating the main structure of the photodetector chip 2; forming an electrical isolation trench 23 on the top surface of the main structure to isolate the LD chip region on the top surface; and then growing the main structure of the laser chip 1 within the LD chip region of the main structure. This embodiment illustrates one implementation method. After fabricating the main structure of the PN electrode out-of-plane photodetector chip using an InP / InGaAsP planar waveguide structure, the main structure is a semi-finished structure that does not include the PD-P bonding region 22, N-side electrode 24, and other structures of the photodetector chip 2. On the top surface of the main structure, i.e., the P surface, an electrically isolated channel pattern is produced through a mask plate photolithography process. After etching, an electrically isolated channel 23 is obtained. By arranging the pattern, multiple different areas can be separated on the top surface, one of which is the LD chip area. Then, the main structure of the laser chip 1 is grown in the LD chip area. The growth method is preferably a selective epitaxial growth technology. The PN electrode of the InP / AlGaInAs ridge waveguide structure designed on the semi-insulating InP substrate material can be grown upward from the LD chip area to form the main structure of the laser chip on the same plane. Due to the process of semiconductor crystal growth, the light-emitting cavity surface of the laser chip 1 and the light-receiving cavity surface of the photodetector chip 2 can be completely flush. Preferably, the electrically isolated channel pattern can also separate the LD-P bonding area 18, the LD-N bonding area 17, and the PD-P bonding area 22 on the top surface to realize the production of the P-side electrode on the top surface of the photodetector chip 2.

[0027] To further optimize the above solution, please refer to Figure 1 、 Figure 2 and Figure 3 The electrically isolated trenches 23 are covered with an insulating material. In this embodiment, isolation is achieved by covering the electrically isolated trenches 23 with an insulating material. Various covering methods are possible, including growing the insulating material directly on the electrically isolated trenches 23. Another method is to grow the insulating material on the entire top surface of the photodetector chip 2, so that all electrically isolated trenches 23 are covered with the insulating material. The insulating material in areas other than the electrically isolated trenches 23 is then removed through an etching process. Preferably, the insulating material is SiO2.

[0028] See also Figure 1 、 Figure 2 and Figure 3A P-side electrode is fabricated on the top surface of the photodetector chip 2, an N-side electrode 24 is fabricated on the bottom surface of the photodetector chip 2, and a PN electrode is fabricated on the top surface of the laser chip 1. In this embodiment, specifically, mask lithography and metal evaporation processes are used to simultaneously fabricate the P electrode 20 and N electrode 19 on the laser chip 1, as well as the corresponding electrodes in the LD-P bonding area 18, LD-N bonding area 17, and PD-P bonding area 22 on the top surface of the photodetector chip 2. Finally, a metal evaporation process is used to fabricate the N-side electrode 24 on the bottom surface of the photodetector chip 2.

[0029] See also Figure 1 、 Figure 2 and Figure 3 After the photodetector chip 2 is fabricated, the laser chip 1 is integrated onto the photodetector chip 2. Specifically, this includes providing a eutectic bonding area on the fabricated photodetector chip 2 and attaching the laser chip 1 to the eutectic bonding area. This embodiment illustrates another implementation whereby a separate laser chip 1 can be directly attached and placed onto the eutectic bonding area after the photodetector chip 2 is fabricated, achieving the same effect.

[0030] See also Figure 1 、 Figure 2 and Figure 3 The present invention provides an integrated optical transceiver chip, which can be manufactured using the above method. Specifically, the integrated optical transceiver chip includes a photodetector chip 2 and a laser chip 1 integrated on the photodetector chip 2. The photodetector chip 2 and the laser chip 1 are stacked.

[0031] See also Figures 1 to 3 The light-emitting cavity surface of the photodetector chip 2 and the light-receiving cavity surface of the laser chip 1 are aligned and on the same side. In this embodiment, the semiconductor crystal growth process described above allows the light-emitting and light-receiving cavity surfaces to be aligned and on the same side. Furthermore, their dimensions and positions are controllable, with virtually no mechanical error. This greatly facilitates subsequent optical coupling, making the optical path simpler and easier to couple than with conventional chips.

[0032] See also Figures 1 to 3The projected area of ​​the photodetector chip 2 on a horizontal plane is larger than the projected area of ​​the laser chip 1 on a horizontal plane. In this embodiment, for high-speed applications where the laser chip 1 generates a lot of heat, the overall area of ​​the photodetector chip 2 is increased. Specifically, the cross-sectional area of ​​the light absorption layer of the photodetector chip 2 is made larger. On the one hand, compared with the light absorption layer of a traditional vertical-incidence photodetector, the light absorption layer of the planar waveguide structure photodetector chip has a larger cross-sectional area and a thinner thickness, which can absorb more photons and allow electrons and holes to reach the N-region and P-region more quickly, thereby improving the responsivity of the photodetector chip 2. On the other hand, because the photodetector chip 2 itself generates little heat, it can also function similarly to a CoC substrate. When the laser chip 1 is integrated on the photodetector chip 2, the larger area of ​​the photodetector chip 2 can effectively dissipate heat from the laser chip 1, thereby improving the electro-optical conversion efficiency of the laser chip 1.

[0033] See also Figures 1 to 3 The laser chip 1 includes a quantum well layer 3 and a ridge stripe 21, and the photodetector chip 2 includes a light absorption layer 4. Laser light from the laser chip 1 can be emitted from the quantum well layer 3, and the photodetector chip 2 can receive the emitted laser light through the light absorption layer 4. The quantum well layer 3 and the light absorption layer 4 are stacked on top of each other and arranged parallel to each other.

[0034] See also Figures 1 to 3The present invention provides an optical module that, in addition to the aforementioned transceiver integrated optical chip, also includes an optical fiber 10, a lens, a filter structure, a PCB board 13, and the like. A collimating lens 6 and a first filter structure 8 are sequentially provided on the transmission light path 11 of the laser chip 1, and a converging lens 7 and a second filter structure 9 are sequentially provided on the reception light path 12 of the photodetector chip 2. Specifically, the transceiver integrated optical chip is placed as a whole on the PCB board 13, wherein the N-side electrode 24 of the photodetector is bonded and interconnected with the GND surface of the PCB board 13. When qualified light enters the light absorption layer 4 of the photodetector chip 2, electron-hole pairs, that is, photogenerated carriers, are generated. Under the action of an external reverse bias electric field, electrons will drift to the N region and holes will drift to the P region, thereby forming a photogenerated current. The N-side electrode 24 serves as an output channel for the electrons of the photogenerated carriers. The PD-P bonding area 22 of the photodetector chip 2 can be interconnected with the external TIAVCC metal electrode 14 by metal bonding, serving as an output channel for the holes of the photogenerated carriers of the photodetector chip 2. The LD-P bonding area 18 on the top surface of the photodetector chip 2 is interconnected with the P electrode 20 of the laser chip 1 by metal bonding. The LD-P bonding area 18 serves as the current injection area for the laser chip 1 and is interconnected with the external current injection electrode 15 by metal bonding. The LD-N bonding area 17 on the top surface of the photodetector chip 2 is interconnected with the N electrode 19 of the laser chip 1 by metal bonding. The LD-N bonding area 17 is further interconnected with the external circuit GND electrode 16. A set of two lenses, each in an upper and lower structure, are arranged in parallel at the front end of the cavity of the transceiver integrated optical chip. The two lenses are stacked by a bracket 5. The collimating lens 6 is used to collimate the light emitted by the laser chip 1, and the converging lens 7 is used to converge the light received by the photodetector chip 2. At the other end of the lens, a set of two filter materials with different refractive indices, namely the first filter structure 8 and the second filter structure 9, are arranged in an upper and lower structure. Both ends of these filter structures are coated with anti-reflection coatings. In addition, an optical fiber 10 is arranged at the other end of the filter material. After the light emitted from the quantum well layer 3 of the laser chip 1 is collimated by the collimating lens 6, the parallel light enters the first filtering structure 8, passes through the tapered structure at the other end of the first filtering structure 8, forms convergent light, enters the optical fiber 10, and is transmitted to the receiving end of the opposite optical module through the optical fiber 10; the light emitted from the opposite optical module in the optical fiber 10 enters the second filtering structure 9, the parallel light enters the converging lens 7, and the focused convergent light is coupled into the light absorption layer 4 of the photodetector chip 2.Because the refractive indices of the first filtering structure 8 and the second filtering structure 9 are different, the light emitted by the laser chip 1 and the light received by the photodetector chip 2 are of different wavelengths and generally have a large wavelength interval. Therefore, they can only propagate in corresponding materials, and both have a higher refractive index than air, so they cannot enter other materials, nor can they be refracted into the air during propagation. They can only enter or emit into the air at both ends of the material, and then enter the optical fiber 10 or receive the light emitted from the optical fiber 10, ensuring the output of the emitted light and the input of the received light, and the two do not interfere with each other.

[0035] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A transceiver integrated optical chip, characterized by: The invention comprises a photodetector chip and a laser chip, wherein the laser chip and the photodetector chip are stacked, the laser chip is integrated on the top surface of the photodetector chip, the quantum well layer of the laser chip is arranged in parallel with the light absorption layer of the photodetector chip, the light output cavity surface of the photodetector chip and the light receiving cavity surface of the laser chip are on the same side and flush, and the projected area of ​​the photodetector chip on the horizontal plane is larger than the projected area of ​​the laser chip on the horizontal plane.

2. The transceiver integrated optical chip according to claim 1, wherein: A PN electrode is provided on the top surface of the laser chip.

3. The transceiver integrated optical chip according to claim 1, wherein: The top surface of the photodetector chip is provided with a P-side electrode, and the bottom surface of the photodetector chip is provided with an N-side electrode.

4. The transceiver integrated optical chip according to claim 1, wherein: An electrical isolation trench is provided on the top surface of the photodetector chip. The electrical isolation trench at least encloses an LD chip region, and the laser chip is integrated in the LD chip region.

5. An optical module, characterized in that: The optical transceiver integrated chip comprises the optical transceiver integrated optical chip according to any one of claims 1 to 4, wherein the bottom surface of the optical detector chip is electrically connected to the PCB board.

6. The optical module according to claim 5, wherein: A first filtering structure is provided on the emission light path of the laser chip, and a second filtering structure is provided on the receiving light path of the photodetector chip. The refractive indexes of the first filtering structure and the second filtering structure are different.

7. The optical module according to claim 6, wherein: A collimating lens is further provided on the emission light path of the laser chip, and a converging lens is further provided on the receiving light path of the photodetector chip. The collimating lens is located between the laser chip and the first filtering structure, and the converging lens is located between the photodetector chip and the second filtering structure.

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