Optical module and preparation method of optical chip
By adopting a two-wafer process in optical communication, the SiN waveguide and silicon waveguide are deposited and bonded together, the substrate leakage loss problem caused by the close distance between the SiN waveguide of the optical chip and the silicon substrate is solved, and higher optical chip performance is achieved.
Patent Information
- Application Number
- CN202311085828.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-25
- Publication Date
- 2025-02-25
AI Technical Summary
In optical communication, the distance between the SiN waveguide of the optical chip and the silicon substrate is close, resulting in substrate leakage loss problems.
A two-wafer process is adopted, one wafer is deposited with SiN waveguides and the other wafer is deposited with silicon waveguides and bonded together to make the distance between the SiN waveguide and the silicon waveguide to prevent light leakage to the substrate.
It effectively reduces substrate leakage losses and improves the performance of optical chips.
Smart Images
Figure CN119511444A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of optical communication technology, and in particular to a method for preparing an optical module and an optical chip. Background Art
[0002] Optical communication technology is used in new services and application modes such as cloud computing, mobile Internet, and video. In optical communication, optical modules are devices that realize photoelectric signal conversion and are one of the key components in optical communication equipment. Among them, due to the advantages of optical chips such as small size, high integration density, and low cost, the use of optical chips to realize electro-optical-photoelectric conversion has become a mainstream solution for high-speed optical modules.
[0003] Optical chips are generally made using silicon photonics technology. In order to obtain better device performance, traditional silicon photonics technology usually requires the development of a process that integrates low-pressure chemical vapor deposition (LPCVD) SiN to integrate SiN waveguides into the optical chip and achieve coupling connection between the optical chip and the optical fiber through the SiN waveguide.
[0004] However, since the deposition of LPCVD SiN requires ultra-high temperatures, it must be carried out in the early stages of the silicon photonics process. At this time, the distance between the SiN waveguide and the silicon waveguide is very close. Based on this, the SiN waveguide is very close to the silicon substrate, which poses a challenge to the design of SiN devices due to substrate leakage losses. Summary of the invention
[0005] The embodiments of the present disclosure provide a method for preparing an optical module and an optical chip, so as to reduce the substrate leakage loss of the optical chip in the optical module.
[0006] In a first aspect, the present disclosure provides an optical module, comprising:
[0007] Circuit boards;
[0008] A light source, electrically connected to the circuit board, the light source being used to generate light that does not carry a signal;
[0009] an optical chip, optically connected to the light source, and configured to receive light generated by the light source that does not carry a signal, and to receive an external optical signal; wherein the optical chip comprises:
[0010] a first substrate;
[0011] A first buried layer is arranged on the first substrate along the epitaxial growth direction;
[0012] A first cladding layer is arranged on the first buried layer along the epitaxial growth direction, wherein a first waveguide and a first metal electrode group are arranged in the first cladding layer, the first waveguide and the first metal electrode group are far away from the first substrate, and a first gap is formed between the first waveguide and the first substrate;
[0013] A second cladding is arranged on the first cladding along the epitaxial growth direction, a second waveguide and a second metal electrode group are arranged in the second cladding, the second waveguide is far away from the first cladding, the second waveguide is coupled to the first waveguide, and a second gap is provided between the first waveguide and the second waveguide; the second metal electrode group is close to the first cladding, and the second metal electrode group is bonded to the first metal electrode group;
[0014] A second buried layer is arranged on the second cladding layer along the epitaxial growth direction, and one side of the second waveguide is in contact with and connected to the second buried layer;
[0015] An optical fiber is coupled to the first waveguide and is used to transmit an optical signal.
[0016] In a second aspect, the present disclosure provides a method for preparing an optical chip, the method comprising:
[0017] growing a first buried layer along the first substrate;
[0018] Growing a first cladding layer along the first buried layer, and forming a first waveguide by high-temperature deposition in the first cladding layer, wherein a first gap is provided between the first waveguide and the first substrate;
[0019] forming a first metal electrode group in the first cladding layer;
[0020] growing a second buried layer along the second substrate;
[0021] Depositing a grating coupler, a second waveguide, a modulator, a third waveguide, an adjustable attenuator and a detector on the second buried layer;
[0022] Growing a second cladding on the grating coupler, the second waveguide, the modulator, the third waveguide, the adjustable attenuator and the detector, and forming a second metal electrode group in the second cladding;
[0023] Etching via holes in the second cladding layer, wherein the modulator, the adjustable attenuator and the detector are electrically connected to the second metal electrode group through the via holes;
[0024] flipping the second cladding layer and placing it on the first cladding layer, and bonding the first metal electrode group to the second metal electrode group so that a second gap exists between the first waveguide and the second waveguide;
[0025] removing the second substrate, and growing a third cladding layer on the second buried layer;
[0026] A third metal electrode group is formed in the third cladding layer, and via holes are etched in the third cladding layer, the second buried layer and the second cladding layer. The third metal electrode group is electrically connected to the second metal electrode group through the via holes.
[0027] It can be seen from the above embodiments that the optical module provided by the embodiments of the present disclosure includes a circuit board, a light source electrically connected to the circuit board, an optical chip and an optical fiber, the light source is used to generate light that does not carry a signal, the optical chip is optically connected to the light source, the optical chip is used to receive the light that does not carry a signal generated by the light source, modulate the light that does not carry a signal, and couple the modulated signal light to the optical fiber, and the optical chip is used to receive an external optical signal transmitted by the optical fiber to realize the conversion of the photoelectric signal; the optical chip includes a first substrate, a first buried layer, a first cladding layer, a second cladding layer and a second buried layer, the first buried layer is arranged in the first cladding layer along the epitaxial growth direction. On a substrate, a first cladding is arranged on a first buried layer along an epitaxial growth direction, a first waveguide and a first metal electrode group are arranged in the first cladding, the first waveguide and the first metal electrode group are far away from the first substrate, and a first gap is provided between the first waveguide and the first substrate; that is, the first waveguide is deposited on the first substrate of a wafer by using an LPCVD process, and a silicon waveguide is not deposited on the wafer. Compared with first depositing the silicon waveguide on a wafer and then depositing the first waveguide, the distance between the first waveguide and the first substrate can be increased, and the light transmitted by the first waveguide can be prevented from leaking to the first substrate, thereby reducing the substrate leakage loss. The second cladding is arranged on the first cladding along the epitaxial growth direction, the second buried layer is arranged on the second cladding along the epitaxial growth direction, the second waveguide and the second metal electrode group are arranged in the second cladding, the second waveguide is far away from the first cladding, the second waveguide is coupled to the first waveguide, and a second gap is provided between the second waveguide and the first waveguide to increase the distance between the first waveguide and the second waveguide; the second metal electrode group is close to the first cladding, the second metal electrode group is bonded to the first metal electrode group to achieve a bonding connection between the second cladding and the first cladding; that is, the second waveguide and the second metal electrode group are deposited on another wafer, and the silicon nitride waveguide is not deposited on the wafer, so as to avoid the high temperature during the deposition of the silicon nitride waveguide affecting the metal electrode.
[0028] The optical chip in the present disclosure has two wafers, a first waveguide is deposited on one wafer, and a second waveguide is deposited on the other wafer, so as to avoid the high temperature during the deposition of the first waveguide affecting the functional devices and metal electrodes in the wafers. Then, the wafer where the first waveguide is located is placed at the bottom, and the wafer where the second waveguide is located is placed at the top to bond them to form an optical chip. In this way, the first waveguide which is very far away from the substrate is integrated in the optical chip, which increases the distance between the first waveguide and the second waveguide, avoids the light transmitted by the first waveguide from leaking to the substrate, and reduces the substrate leakage loss. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings required to be used in some embodiments of the present disclosure. Obviously, the drawings described below are only drawings of some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not intended to limit the actual size of the product involved in the embodiments of the present disclosure, the actual process of the method, the actual timing of the signal, etc.
[0030] Figure 1 A partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure;
[0031] Figure 2 A partial structural diagram of a host computer provided according to some embodiments of the present disclosure;
[0032] Figure 3 A structural diagram of an optical module provided according to some embodiments of the present disclosure;
[0033] Figure 4 An exploded view of an optical module provided according to some embodiments of the present disclosure;
[0034] Figure 5 A partial structural diagram of an optical module provided according to some embodiments of the present disclosure;
[0035] Figure 6 A partial cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 1 ;
[0036] Figure 7 A partial cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 2 ;
[0037] Figure 8 A cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 1 ;
[0038] Fig. 9 A cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 2 ;
[0039] Fig.10 A flowchart of a method for preparing an optical chip according to some embodiments of the present disclosure;
[0040] Fig.11 A partial structural block diagram of an optical module provided according to some embodiments of the present disclosure. DETAILED DESCRIPTION
[0041] The following will be combined with the accompanying drawings to clearly and in detail describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.
[0042] In optical communication technology, in order to establish information transmission between information processing devices, it is necessary to load information onto light and use the propagation of light to achieve information transmission. Here, the light loaded with information is an optical signal. When optical signals are transmitted in information transmission equipment, the loss of optical power can be reduced, so high-speed, long-distance, and low-cost information transmission can be achieved. The signals that information processing equipment can recognize and process are electrical signals. Information processing equipment usually includes optical network terminals (Optical Network Unit, ONU), gateways, routers, switches, mobile phones, computers, servers, tablets, televisions, etc., and information transmission equipment usually includes optical fibers and optical waveguides.
[0043] The optical module can realize the mutual conversion between optical signals and electrical signals between information processing equipment and information transmission equipment. For example, at least one of the optical signal input end or the optical signal output end of the optical module is connected to an optical fiber, and at least one of the electrical signal input end or the electrical signal output end of the optical module is connected to an optical network terminal; the first optical signal from the optical fiber is transmitted to the optical module, and the optical module converts the first optical signal into a first electrical signal, and transmits the first electrical signal to the optical network terminal; the second electrical signal from the optical network terminal is transmitted to the optical module, and the optical module converts the second electrical signal into a second optical signal, and transmits the second optical signal to the optical fiber. Since multiple information processing devices can transmit information through electrical signals, at least one of the multiple information processing devices needs to be directly connected to the optical module, and all information processing devices do not need to be directly connected to the optical module. Here, the information processing device directly connected to the optical module is called the upper computer of the optical module. In addition, the optical signal input end or the optical signal output end of the optical module can be called an optical port, and the electrical signal input end or the electrical signal output end of the optical module can be called an electrical port.
[0044] Figure 1 FIG. 1 is a partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure. Figure 1 As shown, the optical communication system mainly includes a remote information processing device 1000 , a local information processing device 2000 , a host computer 100 , an optical module 200 , an optical fiber 101 and a network cable 103 .
[0045] One end of the optical fiber 101 extends toward the remote information processing device 1000, and the other end of the optical fiber 101 is connected to the optical module 200 through the optical port of the optical module 200. The optical signal can be totally reflected in the optical fiber 101, and the propagation of the optical signal in the total reflection direction can almost maintain the original optical power. The optical signal undergoes multiple total reflections in the optical fiber 101 to transmit the optical signal from the remote information processing device 1000 to the optical module 200, or to transmit the optical signal from the optical module 200 to the remote information processing device 1000, thereby realizing long-distance, low-power loss information transmission.
[0046] The optical communication system may include one or more optical fibers 101, and the optical fibers 101 are detachably connected or fixedly connected to the optical module 200. The host computer 100 is configured to provide data signals to the optical module 200, receive data signals from the optical module 200, or monitor or control the working state of the optical module 200.
[0047] The host computer 100 includes a substantially rectangular housing and an optical module interface 102 disposed on the housing. The optical module interface 102 is configured to connect to the optical module 200 so that the host computer 100 and the optical module 200 establish a unidirectional or bidirectional electrical signal connection.
[0048] The host computer 100 also includes an external electrical interface, which can be connected to an electrical signal network. For example, the external electrical interface includes a Universal Serial Bus (USB) interface or a network cable interface 104, and the network cable interface 104 is configured to access the network cable 103 so that the host computer 100 establishes a unidirectional or bidirectional electrical signal connection with the network cable 103. One end of the network cable 103 is connected to the local information processing device 2000, and the other end of the network cable 103 is connected to the host computer 100, so as to establish an electrical signal connection between the local information processing device 2000 and the host computer 100 through the network cable 103. For example, the third electrical signal sent by the local information processing device 2000 is transmitted to the host computer 100 through the network cable 103, and the host computer 100 generates a second electrical signal according to the third electrical signal. The second electrical signal from the host computer 100 is transmitted to the optical module 200, and the optical module 200 converts the second electrical signal into a second optical signal, and transmits the second optical signal to the optical fiber 101, and the second optical signal is transmitted to the remote information processing device 1000 in the optical fiber 101. For example, the first optical signal from the remote information processing device 1000 is transmitted through the optical fiber 101, and the first optical signal from the optical fiber 101 is transmitted to the optical module 200, and the optical module 200 converts the first optical signal into a first electrical signal, and the optical module 200 transmits the first electrical signal to the host computer 100, and the host computer 100 generates a fourth electrical signal according to the first electrical signal, and transmits the fourth electrical signal to the local information processing device 2000. It should be noted that the optical module is a tool for realizing the mutual conversion between optical signals and electrical signals. During the conversion process between the optical signals and electrical signals, the information does not change, but the encoding and decoding methods of the information can change.
[0049] In addition to the optical network terminal, the host computer 100 also includes an optical line terminal (OLT), an optical network device (ONT), or a data center server.
[0050] Figure 2 1 is a partial structural diagram of a host computer according to some embodiments of the present disclosure. In order to clearly show the connection relationship between the optical module 200 and the host computer 100, Figure 2 Only the structure of the host computer 100 related to the optical module 200 is shown. Figure 2 As shown, the host computer 100 further includes a PCB circuit board 105 disposed in the housing, a cage 106 disposed on the surface of the PCB circuit board 105, a heat sink 107 disposed on the cage 106, and an electrical connector disposed inside the cage 106. The electrical connector is configured to access the electrical port of the optical module 200; the heat sink 107 has a protruding structure such as fins to increase the heat dissipation area.
[0051] The optical module 200 is inserted into the cage 106 of the host computer 100, and the cage 106 fixes the optical module 200. The heat generated by the optical module 200 is transferred to the cage 106 and then diffused through the heat sink 107. After the optical module 200 is inserted into the cage 106, the electrical port of the optical module 200 is connected to the electrical connector inside the cage 106, so that the optical module 200 establishes a bidirectional electrical signal connection with the host computer 100. In addition, the optical port of the optical module 200 is connected to the optical fiber 101, so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101.
[0052] Figure 3 is a structural diagram of an optical module provided according to some embodiments of the present disclosure, Figure 4 FIG. 1 is an exploded view of an optical module provided according to some embodiments of the present disclosure. Figure 3 and Figure 4 As shown, the optical module 200 includes a shell, a circuit board 300 disposed in the shell, an optical chip 900, a light source 1100, an optical fiber adapter 700, and an optical fiber connecting the optical chip 900 and the optical fiber adapter 700, but the present disclosure is not limited thereto.
[0053] The housing comprises an upper housing 201 and a lower housing 202 . The upper housing 201 covers the lower housing 202 to form the housing having two openings 204 and 205 . The outer contour of the housing is generally a square body.
[0054] In some embodiments, the lower shell 202 includes a bottom plate 2021 and two lower side plates 2022 located on both sides of the bottom plate 2021 and arranged perpendicular to the bottom plate 2021; the upper shell 201 includes a cover plate 2011, and the cover plate 2011 covers the two lower side plates 2022 of the lower shell 202 to form the above-mentioned shell.
[0055] In some embodiments, the lower shell 202 includes a bottom plate 2021 and two lower side plates 2022 located on both sides of the bottom plate 2021 and vertically arranged with the bottom plate 2021; the upper shell 201 includes a cover plate 2011 and two upper side plates located on both sides of the cover plate 2011 and vertically arranged with the cover plate 2011, and the two upper side plates are combined with the two lower side plates 2022 to realize that the upper shell 201 covers the lower shell 202.
[0056] The direction of the line connecting the two openings 204 and 205 may be consistent with the length direction of the optical module 200, or may be inconsistent with the length direction of the optical module 200. For example, the opening 204 is located at the end of the optical module 200 ( Figure 3 The opening 205 is also located at the end of the optical module 200 ( Figure 3Alternatively, the opening 204 is located at the end of the optical module 200, and the opening 205 is located at the side of the optical module 200. The opening 204 is an electrical port, and the gold finger 301 of the circuit board 300 extends from the electrical port and is inserted into the electrical connector of the host computer 100; the opening 205 is an optical port, which is configured to access the external optical fiber 101 so that the optical fiber 101 is connected to the optical chip 900 in the optical module 200.
[0057] The assembly method of combining the upper housing 201 and the lower housing 202 is adopted, so that the circuit board 300, the optical chip 900, the light source 1100, the optical fiber adapter 700, and the optical fiber connecting the optical chip 900 and the optical fiber adapter 700 are conveniently installed in the above housing, and the above components can be encapsulated and protected by the upper housing 201 and the lower housing 202. In addition, when assembling the circuit board 300, the optical chip 900, the light source 1100, the optical fiber adapter 700, and the optical fiber connecting the optical chip 900 and the optical fiber adapter 700, the assembly method of the upper housing 201 and the lower housing 202 is adopted, so that the positioning components, heat dissipation components, and electromagnetic shielding components of these components are conveniently arranged, which is conducive to the automated production.
[0058] In some embodiments, the upper shell 201 and the lower shell 202 are made of metal materials to facilitate electromagnetic shielding and heat dissipation.
[0059] In some embodiments, the optical module 200 further includes an unlocking component 600 located outside its housing. The unlocking component 600 is configured to achieve a fixed connection between the optical module 200 and the host computer 100, or to release the fixed connection between the optical module 200 and the host computer 100.
[0060] For example, the unlocking component 600 is located on the outside of the two lower side plates 2022 of the lower housing 202, and includes a snap-fit component that matches the cage 106 of the host computer 100. When the optical module 200 is inserted into the cage 106, the snap-fit component of the unlocking component 600 fixes the optical module 200 in the cage 106; when the unlocking component 600 is pulled, the snap-fit component of the unlocking component 600 moves accordingly, thereby changing the connection relationship between the snap-fit component and the host computer, so as to release the fixation of the optical module 200 and the host computer, so that the optical module 200 can be pulled out of the cage 106.
[0061] The circuit board 300 includes circuit traces, electronic components and chips, etc. The electronic components and chips are connected according to the circuit design through the circuit traces to realize the functions of power supply, electrical signal transmission and grounding. The electronic components may include capacitors, resistors, transistors, metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). The chip may include a microcontroller unit (Microcontroller Unit, MCU), a laser driver chip, a transimpedance amplifier (Transimpedance Amplifier, TIA), a limiting amplifier (Limiting Amplifier, LA), a clock and data recovery chip (Clock and Data Recovery, CDR), a power management chip, and a digital signal processing (Digital Signal Processing, DSP) chip.
[0062] The circuit board 300 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also realize the load-bearing function. For example, the rigid circuit board can stably carry the above-mentioned electronic components and chips; the rigid circuit board can also be inserted into the electrical connector in the cage 106 of the host computer 100.
[0063] The circuit board 300 also includes a gold finger 301 formed on the end surface thereof. The gold finger 301 is composed of a plurality of independent pins. The circuit board 300 is inserted into the cage 106, and the gold finger 301 is connected to the electrical connector in the cage 106. The gold finger 301 can be provided on only one side of the circuit board 300 (e.g. Figure 4 The upper surface shown in the figure) can also be set on the upper and lower surfaces of the circuit board 300 to provide more pins, so as to adapt to occasions where the number of pins is large. The gold finger 301 is configured to establish an electrical connection with the host computer to achieve power supply, grounding, two-wire synchronous serial (Inter-Integrated Circuit, I2C) signal transmission, data signal transmission, etc. Of course, flexible circuit boards are also used in some optical modules. Flexible circuit boards are generally used in conjunction with rigid circuit boards to supplement rigid circuit boards.
[0064] In some embodiments, the optical chip 900 and the light source 1100 are physically separated from the circuit board 300 and then electrically connected to the circuit board 300 through a flexible circuit board or an electrical connector.
[0065] In some embodiments, the optical chip 900 and the light source 1100 may be directly disposed on the circuit board 300. For example, the optical chip 900 and the light source 1100 may be disposed on the surface of the circuit board 300 or on the side of the circuit board 300.
[0066] Figure 5 FIG. 1 is a partial structural diagram of an optical module provided according to some embodiments of the present disclosure. Figure 5 As shown, the optical chip 900 is disposed on the circuit board 300, and the optical chip 900 is electrically connected to the circuit board 300. For example, the optical chip 900 is electrically connected to the circuit board 300 by wire bonding, and the periphery of the optical chip 900 is connected to the circuit board 300 through multiple conductive wires. Therefore, the optical chip 900 is generally disposed on the surface of the circuit board 300.
[0067] The optical chip 900 and the light source 1100 can be optically connected via an optical fiber ribbon. The optical chip 900 receives light that does not carry a signal from the light source 1100 via the optical fiber ribbon, and the optical chip 900 modulates the light that does not carry a signal to obtain signal light. The optical chip 900 and the light source 1100 can also be directly end-face coupled. The optical chip 900 directly receives light that does not carry a signal from the light source 1100, and the optical chip 900 modulates the light that does not carry a signal.
[0068] The optical chip 900 and the optical fiber adapter 700 can be optically connected through the transmitting optical fiber and the receiving optical fiber, and the optical fiber adapter 700 can realize the optical connection with the external optical fiber of the optical module. The signal light modulated by the optical chip 900 is transmitted to the optical fiber adapter 700 through the transmitting optical fiber, and then transmitted to the external optical fiber 101 through the optical fiber adapter 700 to realize the emission of light; the light transmitted by the external optical fiber is transmitted to the receiving optical fiber through the optical fiber adapter 700, and then transmitted to the optical chip 900 through the receiving optical fiber. The optical chip 900 converts the received optical signal into an electrical signal to realize the reception of light.
[0069] In some embodiments, the optical chip 900 is a silicon photonic chip, which is provided with an input optical port, an output optical port, a monitoring optical port, a high-speed electrical signal interface, and a DC bias signal interface, etc., wherein the input optical port includes a first input optical port and a second input optical port, the first input optical port is used to couple the light output by the light source 1100 into the silicon photonic chip, the second input optical port is used to couple the signal light transmitted by the optical fiber outside the optical module into the silicon photonic chip, and the output optical port is used to couple the signal light modulated by the silicon photonic chip out of the optical chip 900.
[0070] The optical chip 900 is made using traditional silicon photonics technology. In order to obtain better device performance, it is usually necessary to develop a process for integrating low-pressure chemical vapor deposition (LPCVD) SiN in the silicon photonics chip to integrate SiN waveguides in the optical chip and achieve coupling connection between the optical chip 900 and the optical fiber through the SiN waveguides.
[0071] However, when the optical chip 900 is prepared by the silicon photonics process, functional devices such as silicon waveguides and modulators are first deposited on the silicon substrate. Since the deposition of LPCVD SiN requires ultra-high temperature, in order to avoid deformation or ablation of the metal electrodes in the optical chip 900 caused by the high temperature during the deposition of SiN, the SiN waveguide must be deposited in the early stage of the silicon photonics process. That is, after the deposition of the silicon waveguide is completed, the SiN waveguide is deposited on top of the silicon waveguide using the LPCVD process, and then a metal electrode is formed on top of the SiN waveguide. At this time, the distance between the SiN waveguide and the silicon waveguide is very close. Based on this, the SiN waveguide is very close to the silicon substrate, which increases the substrate leakage loss.
[0072] In order to solve the above problems, the present invention performs silicon photonics process operations on two wafers, deposits SiN waveguides on one wafer without depositing silicon waveguides, thereby preventing the high temperature during the deposition of SiN waveguides from affecting the functional devices and metal electrodes in the wafer; deposits silicon waveguides on the other wafer without depositing SiN waveguides, and bonds the two wafers together so that the SiN waveguides are located at the bottom and the silicon waveguides are located at the top. In this way, a SiN waveguide that is very far away from the substrate is integrated in the optical chip 900, increasing the distance between the SiN waveguide and the silicon waveguide, preventing the light transmitted by the first waveguide from leaking to the substrate, and reducing substrate leakage loss.
[0073] Figure 6 A partial cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 1 , Figure 7 A partial cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 2 .like Figure 6 and Figure 7 As shown, the optical chip 900 includes a first substrate 9101, a first buried layer 9102 and a first cladding 9103. The first buried layer 9102 is arranged on the first substrate 9101 along the epitaxial growth direction, and the first cladding 9103 is arranged on the first buried layer 9102 along the epitaxial growth direction, so that the first substrate 9101, the first buried layer 9102 and the first cladding 9103 are arranged in sequence from bottom to top.
[0074] A first bonding surface 9104 is disposed on a side of the first cladding 9103 away from the first substrate 9101 . A first waveguide 905 is disposed in the first cladding 9103 . The first waveguide 905 is adjacent to the first bonding surface 9104 , and a first gap is provided between the first waveguide 905 and the first substrate 9101 .
[0075] In some embodiments, the first waveguide 905 is deposited on the first cladding 9103 using the LPCVD process. The first waveguide 905 is a silicon nitride waveguide. Since no silicon waveguide is provided in the first cladding 9103, the deposition of the first waveguide 905 can be performed in the early stage of the silicon photonic process. In addition, the first waveguide 905 is very far away from the first substrate 9101, which can reduce the leakage of light transmitted by the first waveguide 905 to the first substrate 9101, thereby reducing substrate leakage loss.
[0076] In some embodiments, the first buried layer 9102 has a first height H1, the first cladding layer 9103 has a second height H2, the second height H2 is greater than the first height H1, and the first gap between the first waveguide 905 and the first substrate 9101 is equal to the sum of the first height H1 and the second height H2, so as to increase the size of the first gap through the first buried layer 9102, thereby further reducing the substrate leakage loss.
[0077] In some embodiments, the first height H1 has a size ranging from 2 to 4 μm, the second height H2 has a size ranging from 2 to 8 μm, and the first gap between the first waveguide 905 and the first substrate 9101 has a size ranging from 4 to 12 μm.
[0078] In some embodiments, the first substrate 9101 may be a silicon substrate, and other types of materials may also be selected as the substrate material. The first buried layer 9102 is an insulating layer, and the material of the insulating layer may be silicon dioxide, and the insulating layer material may also be silicon nitride or silicon oxynitride, etc. The insulating layer can achieve full dielectric isolation between the first cladding layer 9103 and the first substrate 9101, and can reduce the leakage of light transmitted by the first waveguide 905 to the first substrate 9101, thereby further reducing the substrate leakage loss.
[0079] A first metal electrode group is also provided in the first cladding 9103, and the first metal electrode group is adjacent to the first bonding surface 9104. The first metal electrode group can be deposited in the later stage of the silicon photonic process, that is, the first waveguide 905 is first deposited in the first cladding 9103, and then the first metal electrode group is formed in the first cladding 9103, so that the high temperature during the deposition of the first waveguide 905 will not affect the first metal electrode group.
[0080] The first metal electrode group includes a first metal electrode 9105, a fifth metal electrode 9106 and a sixth metal electrode 9107. The first metal electrode 9105, the fifth metal electrode 9106 and the sixth metal electrode 9107 may be located on one side of the first waveguide 905. The first metal electrode 9105 may be located between the fifth metal electrode 9106 and the sixth metal electrode 9107. The fifth metal electrode 9106 may be adjacent to the first waveguide 905, and the sixth metal electrode 9107 may be away from the first waveguide 905.
[0081] Reference Figure 7The optical chip 900 also includes a second substrate 9201, a second buried layer 9202 and a second cladding 9203. The second buried layer 9202 is arranged on the second substrate 9201 along the epitaxial growth direction, and the second cladding 9203 is arranged on the second buried layer 9202 along the epitaxial growth direction, so that the second substrate 9201, the second buried layer 9202 and the second cladding 9203 are arranged in sequence from bottom to top.
[0082] A second bonding surface 9204 is provided on the side of the second cladding 9203 away from the second substrate 9201 , and the second bonding surface 9204 is bonded to the first bonding surface 9104 , so that the second cladding 9203 is arranged on the first cladding 9103 along the epitaxial growth direction to form a bonded optical chip 900 .
[0083] In some embodiments, the second substrate 9201 may be a silicon substrate, and the substrate material may also be other types of materials, such as germanium silicon material, etc., as long as it can be removed in subsequent steps. The second buried layer 9202 is an insulating layer, and the material of the insulating layer may be silicon dioxide, and the insulating layer material may also be silicon nitride or silicon oxynitride, etc.
[0084] In some embodiments, the second buried layer 9202 has a third height H3, the second cladding layer 9203 has a fourth height H4, the third height H3 is less than or equal to the first height H1, and the fourth height H4 is less than the first gap.
[0085] In some embodiments, the third height H3 has a size ranging from 2 to 4 μm, and the fourth height H4 has a size less than 1 μm.
[0086] In some embodiments, the optical chip 900 may further include a top silicon layer, and along the epitaxial growth direction, the top silicon layer is located on the second buried layer 9202, and the second cladding layer 9203 is located on the top silicon layer, and the second buried layer 9202 can achieve full dielectric isolation between the top silicon layer and the second substrate 9201, so as to reduce parasitic capacitance and improve the operating speed. In addition, since the parasitic capacitance is reduced, leakage can also be reduced, and the power consumption of the device implemented on the top silicon layer can be reduced.
[0087] The top layer of silicon can be patterned, photolithographically etched, and formed into silicon optical devices such as silicon waveguides and gratings. Active or passive devices such as modulators, photodetectors, and attenuators can also be formed. A dielectric layer (second cladding 9203) can then be covered over the silicon optical devices, silicon optical active devices, silicon optical passive devices, etc., and then a flattening treatment can be performed so that the second cladding 9203 wraps the silicon optical devices, silicon optical active devices, silicon optical passive devices, etc.
[0088] In some embodiments, functional devices such as silicon waveguides, gratings, modulators, photodetectors, attenuators, etc. may be deposited on the second buried layer 9202, and then the second cladding 9203 may be covered on the functional devices so that the second cladding 9203 wraps the functional devices.
[0089] A grating coupler 901, a third waveguide 902, a modulator 903 and a second waveguide 904 are arranged in the second cladding 9203. The grating coupler 901, the third waveguide 902, the modulator 903 and the second waveguide 904 are located on the side where the second cladding 9203 is connected to the second buried layer 9202. The grating coupler 901 is close to the edge of one side of the second cladding 9203. The grating coupler 901 is optically connected to the light source 1100 so as to couple the light without carrying a signal output by the light source 1100 to the optical chip 900 through the grating coupler 901.
[0090] The input end of the third waveguide 902 is connected to the grating coupler 901, and the output end of the third waveguide 902 is connected to the input end of the modulator 903. The third waveguide 902 couples the light not carrying a signal input by the grating coupler 901 to the modulator 903. The modulator 903 modulates the light not carrying a signal to obtain a modulated signal light.
[0091] In some embodiments, when the modulator 903 modulates light that does not carry a signal, it needs to receive an electrical signal. In order to output the electrical signal to the modulator 903, a second metal electrode group is also provided in the second cladding 9203. The second metal electrode group includes a second metal electrode 9205. The second metal electrode 9205 is adjacent to the second bonding surface 9204. The second metal electrode 9205 is electrically connected to the modulator 903 through a via so as to output the electrical signal to the modulator 903 through the second metal electrode 9205.
[0092] Figure 8 A cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 1 .like Figure 8 As shown, a first substrate 9101, a first buried layer 9102 and a first cladding 9103 are sequentially arranged from bottom to top, a first waveguide 905 and a first metal electrode group are arranged in the first cladding 9103, a second substrate 9201, a second buried layer 9202 and a second cladding 9203 are sequentially arranged from bottom to top, a grating coupler 901, a third waveguide 902, a modulator 903, a second waveguide 904 and a second metal electrode group are arranged in the second cladding 9203, the first substrate 9101 is placed at the bottom, the second substrate 9201 is turned over, the first bonding surface 9104 on the upper surface of the first cladding 9103 and the second bonding surface 9204 on the upper surface of the second cladding 9203 are bonded together, and then high temperature and high pressure are used to achieve bonding connection between the first metal electrode group and the second metal electrode group.
[0093] After bonding the first cladding 9103 and the flipped second cladding 9203 together, the first cladding 9103 and the second cladding 9203 are located between the first buried layer 9102 and the second buried layer 9202, and the distance H2' between the first buried layer 9102 and the second buried layer 9202 is the sum of the second height H2 and the fourth height H4.
[0094] The second waveguide 904 is located above the first waveguide 905, and a second gap H6 is defined between the second waveguide 904 and the first waveguide 905. The output end of the modulator 903 is connected to one end of the second waveguide 904, and the other end of the second waveguide 904 is coupled to the first waveguide 905, so that the signal light modulated by the modulator 903 is transmitted to the first waveguide 905 through the second waveguide 904. The first waveguide 905 couples the signal light to the optical fiber, and then transmits the signal light to the external optical fiber 101 via the optical fiber, thereby realizing light emission.
[0095] In some embodiments, the second waveguide 904 is a silicon waveguide and the first waveguide 905 is a silicon nitride waveguide to achieve a coupling connection between the second waveguide 904 and the first waveguide 905, so that light transmitted by the second waveguide 904 can be coupled to the first waveguide 905, or light transmitted by the first waveguide 905 can be coupled to the second waveguide 904.
[0096] In some embodiments, the fourth height H4 of the second cladding layer 9203 is equal to the second gap H6, so that the second gap H6 between the second waveguide 904 and the first waveguide 905 is less than 1 μm.
[0097] In some embodiments, an adjustable attenuator 907 and a detector 908 may also be provided in the second cladding 9203. Figure 8 In the cross-sectional view shown, the modulator 903 may be located between the adjustable attenuator 907 and the detector 908. After the first cladding 9103 and the second cladding 9203 are bonded together, the adjustable attenuator 907 may be coupled to the first waveguide 905, and the adjustable attenuator 907 is used to receive the received optical signal transmitted by the first waveguide 905 and perform attenuation processing on the received optical signal. That is, the received optical signal transmitted by the external optical fiber 101 is coupled to the adjustable attenuator 907 via the first waveguide 905, and the adjustable attenuator 907 performs attenuation processing on the received optical signal.
[0098] The detector 908 is connected to the adjustable attenuator 907, and the detector 908 is used to convert the received optical signal after attenuation processing into an electrical signal to realize photoelectric conversion and realize light reception.
[0099] In some embodiments, the second metal electrode group further includes a third metal electrode 9206 and a fourth metal electrode 9207, the third metal electrode 9206 and the fourth metal electrode 9207 are adjacent to the second bonding surface 9204, and the second metal electrode 9205 is located between the third metal electrode 9206 and the fourth metal electrode 9207. The third metal electrode 9206 is electrically connected to the adjustable attenuator 907 through a via hole, and the fourth metal electrode 9207 is electrically connected to the detector 908 through a via hole, so as to transmit electrical signals to the adjustable attenuator 907 and the detector 908.
[0100] The first metal electrode group also includes a fifth metal electrode 9106 and a sixth metal electrode 9107. When the first cladding 9103 and the second cladding 9203 are bonded together, the first metal electrode 9105 and the second metal electrode 9205 are bonded together, the fifth metal electrode 9106 and the third metal electrode 9206 are bonded together, and the sixth metal electrode 9107 and the fourth metal electrode 9207 are bonded together to achieve a bonding connection between the first metal electrode group and the second metal electrode group.
[0101] Fig. 9 A cross section of an optical chip in an optical module provided according to some embodiments of the present disclosure Figure 2 .like Fig. 9 As shown, after the first cladding layer 9103 and the second cladding layer 9203 are bonded together, the second substrate 9201 can be removed, and then a multi-layer metal structure can be continuously fabricated above the second buried layer 9202 along the epitaxial growth direction to form the final optical chip 900.
[0102] The optical chip 900 also includes a third cladding 930. Along the epitaxial growth direction, the third cladding 930 is located on the second buried layer 9202. The third cladding 930 has a fifth height H5. A third metal electrode group is arranged in the third cladding 930. The third metal electrode group includes a seventh metal electrode 9301, an eighth metal electrode 9302 and a ninth metal electrode 9303. The seventh metal electrode 9301 is electrically connected to the second metal electrode 9205 through a via hole to transmit an electrical signal to the modulator 903; the eighth metal electrode 9302 is electrically connected to the third metal electrode 9206 through a via hole to transmit an electrical signal to the adjustable attenuator 907; the ninth metal electrode 9303 is electrically connected to the fourth metal electrode 9207 through a via hole to transmit an electrical signal to the detector 908.
[0103] In some embodiments, when growing the third cladding layer 930 on the second buried layer 9202, a portion of the second buried layer 9202 can be removed to reduce the thickness of the second buried layer 9202 so that the height of the second buried layer 9202 is H3', H3'<H3, so as to facilitate electrical connection between the metal electrode in the third cladding layer 930 and the metal electrode in the second cladding layer 9203.
[0104] In the embodiment of the present disclosure, one first waveguide 905 may be disposed in the first cladding 9103, or multiple (two or more) first waveguides 905 may be disposed in the first cladding 9103. The multiple first waveguides 905 may be disposed in a direction perpendicular to the paper surface ( Fig. 9 multiple second waveguides 904 are also arranged in the second cladding 9203, and the multiple second waveguides 904 are arranged side by side in a direction perpendicular to the paper surface, that is, the multiple first waveguides 905 are at an equal distance from the first substrate 9101, and the multiple second waveguides 904 are at an equal distance from the multiple first waveguides 905.
[0105] Two first waveguides 905 may be arranged in the first cladding 9103, and one first waveguide 905 may be used as an output optical waveguide. The light not carrying a signal output by the light source 1100 is coupled to the third waveguide 902 through the grating coupler 901. The third waveguide 902 transmits the light not carrying a signal to the modulator 903. The modulator 903 modulates the light not carrying a signal, and the modulated signal light is transmitted to the second waveguide 904. The second waveguide 904 couples the signal light to the first waveguide 905. The first waveguide 905 couples the signal light to the optical fiber, thereby realizing light emission.
[0106] Another first waveguide 905 can be used as an input optical waveguide. The received optical signal transmitted by the optical fiber is coupled to the adjustable attenuator 907 of the optical chip 900 via the first waveguide 905. The adjustable attenuator 907 attenuates the received optical signal. The attenuated received optical signal is transmitted to the detector 908. The detector 908 converts the received optical signal into an electrical signal, thereby realizing the reception of light.
[0107] In some embodiments, when multiple (two or more) first waveguides 905 are arranged in the first cladding 9103, the multiple first waveguides 905 can be arranged up and down along the epitaxial growth direction, and the spacing between adjacent first waveguides 905 is less than 1.5 μm. A first gap is provided between the first waveguide 905 close to the first substrate 9101 and the first substrate 9101, and the size of the first gap ranges from 4 to 12 μm; a second gap is provided between the first waveguide 905 close to the first bonding surface 9104 and the second waveguide 904, and the second gap is less than 1 μm.
[0108] In some embodiments, two first waveguides 905 are disposed in the first cladding 9103, one first waveguide 905 is adjacent to the first bonding surface 9104, and the other first waveguide 905 is adjacent to the first substrate 9101, the two first waveguides 905 are disposed in the up-and-down direction, a second gap is provided between the first waveguide 905 adjacent to the first bonding surface 904 and the second waveguide 904, a first gap is provided between the first waveguide 905 adjacent to the first substrate 9101 and the first substrate 9101, and the gap between the two first waveguides 905 is less than 1.5 μm.
[0109] A first waveguide 905 is used as an output optical waveguide. The light without signal output by the light source 1100 is coupled to the third waveguide 902 through the grating coupler 901. The third waveguide 902 transmits the light without signal to the modulator 903. The modulator 903 modulates the light without signal. The modulated signal light is transmitted to the second waveguide 904. The second waveguide 904 couples the signal light to the first waveguide 905. The first waveguide 905 couples the signal light to the optical fiber, thereby realizing light emission.
[0110] Another first waveguide 905 serves as an input optical waveguide. The received optical signal transmitted by the optical fiber is coupled to the adjustable attenuator 907 of the optical chip 900 via the first waveguide 905. The adjustable attenuator 907 attenuates the received optical signal. The attenuated received optical signal is transmitted to the detector 908. The detector 908 converts the received optical signal into an electrical signal, thereby realizing light reception.
[0111] In the optical module provided by the present invention, the optical chip has two wafers, SiN waveguides are deposited on one wafer using the LPCVD process, and silicon waveguides, various functional devices and metal electrodes are deposited on the other wafer using the silicon photonic process, thereby preventing the high temperature during the deposition of the SiN waveguide from affecting the functional devices and metal electrodes on the wafer. In this way, the SiN waveguide that is very far away from the substrate is integrated in the optical chip, increasing the distance between the SiN waveguide and the silicon waveguide, preventing the light transmitted by the SiN waveguide from leaking to the substrate, and reducing substrate leakage loss.
[0112] Based on the optical module described in the above embodiment, the embodiment of the present disclosure also provides a method for preparing an optical chip, which deposits a SiN waveguide on one wafer, integrates a silicon waveguide, various functional devices and metal electrodes on another wafer, and bonds the two completed wafers together, thereby increasing the distance between the SiN waveguide and the silicon waveguide, preventing the light transmitted by the SiN waveguide from leaking to the substrate, and reducing substrate leakage loss.
[0113] Fig.10 Flow chart of a method for preparing an optical chip according to some embodiments of the present disclosure. Fig.10 As shown, the method for preparing an optical chip provided in an embodiment of the present disclosure includes:
[0114] S10: growing a first buried layer along the first substrate.
[0115] S20: growing a first cladding layer along the first buried layer, and forming a first waveguide by high-temperature deposition in the first cladding layer, wherein a first gap is provided between the first waveguide and the first substrate.
[0116] S30: forming a first metal electrode group in the first cladding layer.
[0117] S40: growing a second buried layer along the second substrate.
[0118] S50: depositing a grating coupler, a second waveguide, a modulator, a third waveguide, a tuning attenuator and a detector on the second buried layer.
[0119] S60: growing a second cladding on the grating coupler, the second waveguide, the modulator, the third waveguide, the adjustable attenuator and the detector, and forming a second metal electrode group in the second cladding.
[0120] S70: etching via holes in the second cladding layer, and the modulator, the adjustable attenuator and the detector are electrically connected to the second metal electrode group through the via holes.
[0121] S80: flipping the second cladding layer and placing it on the first cladding layer, bonding the first metal electrode group and the second metal electrode group to form a second gap between the first waveguide and the second waveguide.
[0122] S90: removing the second substrate, and growing a third cladding layer on the second buried layer.
[0123] S100: forming a third metal electrode group in the third cladding layer, etching via holes in the third cladding layer, the second buried layer and the second cladding layer, and electrically connecting the third metal electrode group to the second metal electrode group through the via holes.
[0124] Fig.11 FIG. 1 is a partial structural block diagram of an optical module provided according to some embodiments of the present disclosure. Fig.11 As shown, after the optical chip 900 is manufactured by the method for manufacturing the optical chip described in the above embodiment, one end of the grating coupler 901 is optically connected to the light source 1100, and the other end of the grating coupler 901 is connected to one end of the third waveguide 902, so that the light not carrying a signal output by the light source 1100 is coupled to the third waveguide 902 through the grating coupler 901; the other end of the third waveguide 902 is connected to the modulator 903, so that the light not carrying a signal transmitted by the third waveguide 902 is coupled to the modulator 903, and the modulator 903 modulates the light not carrying a signal to obtain signal light.
[0125] The modulator 903 is connected to one end of the second waveguide 904, the other end of the second waveguide 904 is coupled to the first waveguide 905, and the first waveguide 905 is coupled to the optical fiber, so that the modulated signal light is coupled into the optical fiber through the second waveguide 904 and the first waveguide 905, and then transmitted to the external optical fiber 101 via the optical fiber, thereby realizing light emission.
[0126] In some embodiments, the optical chip 900 also includes a fourth waveguide 906, an adjustable attenuator 907 and a detector 908. The fourth waveguide 906 is adjacent to the second input optical port of the optical chip 900. The fourth waveguide 906 has the same structure as the first waveguide 905. One end of the fourth waveguide 906 is coupled to the optical fiber, and the other end of the fourth waveguide 906 is connected to the adjustable attenuator 907. The fourth waveguide 906 couples the received optical signal transmitted by the optical fiber to the adjustable attenuator 907, and the adjustable attenuator 907 attenuates the received optical signal.
[0127] The detector 908 is connected to the adjustable attenuator 907. The detector 908 converts the received optical signal after attenuation processing into an electrical signal to realize photoelectric conversion and achieve light reception.
[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure.
Claims
1. An optical module, characterized in that: include: Circuit boards; A light source, electrically connected to the circuit board, the light source being used to generate light that does not carry a signal; an optical chip, optically connected to the light source, and configured to receive light generated by the light source that does not carry a signal, and to receive an external optical signal; wherein the optical chip comprises: a first substrate; A first buried layer is arranged on the first substrate along the epitaxial growth direction; A first cladding layer is arranged on the first buried layer along the epitaxial growth direction, wherein a first waveguide and a first metal electrode group are arranged in the first cladding layer, the first waveguide and the first metal electrode group are far away from the first substrate, and a first gap is formed between the first waveguide and the first substrate; A second cladding is arranged on the first cladding along the epitaxial growth direction, a second waveguide and a second metal electrode group are arranged in the second cladding, the second waveguide is far away from the first cladding, the second waveguide is coupled to the first waveguide, and a second gap is provided between the first waveguide and the second waveguide; the second metal electrode group is close to the first cladding, and the second metal electrode group is bonded to the first metal electrode group; A second buried layer is arranged on the second cladding layer along the epitaxial growth direction, and one side of the second waveguide is in contact with and connected to the second buried layer; An optical fiber is coupled to the first waveguide and is used to transmit an optical signal.
2. The optical module according to claim 1, characterized in that: The second cladding is also provided with: A grating coupler, used to couple the light generated by the light source and not carrying a signal to the optical chip; a third waveguide, an input end of which is connected to the grating coupler, and the third waveguide is used to transmit the light not carrying a signal; A modulator is connected to the output end of the third waveguide, and the modulator is used to modulate the light not carrying a signal and output a signal light, and the signal light is coupled to the first waveguide through the second waveguide.
3. The optical module according to claim 2, characterized in that: The first metal electrode group includes a first metal electrode, the second metal electrode group includes a second metal electrode, the second metal electrode is electrically connected to the modulator through a via, and the second metal electrode is bonded to the first metal electrode.
4. The optical module according to claim 1, characterized in that: The first buried layer has a first height, the first cladding layer has a second height, and the second height is greater than the first height; The second buried layer has a third height, the second cladding layer has a fourth height, the third height is not greater than the first height, and the fourth height is equal to the second gap.
5. The optical module according to claim 4, characterized in that: The first height has a size range of 2 to 4 μm, the second height has a size range of 2 to 8 μm, the third height has a size range of 2 to 4 μm, and the fourth height is less than 1 μm.
6. The optical module according to claim 5, characterized in that: The first height is 2 μm, the second height is 4 μm, the third height is 1.5 μm, and the fourth height is 0.8 μm.
7. The optical module according to claim 1, characterized in that: The second cladding also includes: an adjustable attenuator, coupled to the first waveguide, the adjustable attenuator being electrically connected to the third metal electrode in the second metal electrode group, the adjustable attenuator being used to receive a received optical signal transmitted by the first waveguide and perform attenuation processing on the received optical signal; A detector is connected to the adjustable attenuator, the detector is electrically connected to the fourth metal electrode in the second metal electrode group, and the detector is used to convert the received light signal into an electrical signal.
8. The optical module according to claim 7, characterized in that: The optical chip further includes a third cladding layer, which is arranged on the second buried layer along the epitaxial growth direction. A third metal electrode group is arranged in the third cladding layer, and the third metal electrode group is electrically connected to the second metal electrode group through a via hole.
9. The optical module according to claim 2, characterized in that: The first waveguide is a silicon nitride waveguide, and the second waveguide and the third waveguide are silicon waveguides.
10. A method for preparing an optical chip, characterized in that: The method comprises: growing a first buried layer along the first substrate; Growing a first cladding layer along the first buried layer, and forming a first waveguide by high-temperature deposition in the first cladding layer, wherein a first gap is provided between the first waveguide and the first substrate; forming a first metal electrode group in the first cladding layer; growing a second buried layer along the second substrate; Depositing a grating coupler, a second waveguide, a modulator, a third waveguide, an adjustable attenuator and a detector on the second buried layer; Growing a second cladding on the grating coupler, the second waveguide, the modulator, the third waveguide, the adjustable attenuator and the detector, and forming a second metal electrode group in the second cladding; Etching via holes in the second cladding layer, wherein the modulator, the adjustable attenuator and the detector are electrically connected to the second metal electrode group through the via holes; flipping the second cladding layer and placing it on the first cladding layer, and bonding the first metal electrode group to the second metal electrode group so that a second gap exists between the first waveguide and the second waveguide; removing the second substrate, and growing a third cladding layer on the second buried layer; A third metal electrode group is formed in the third cladding layer, and via holes are etched in the third cladding layer, the second buried layer and the second cladding layer. The third metal electrode group is electrically connected to the second metal electrode group through the via holes.