Preparation method of optical modulation chip, optical modulation chip and optical module

Abstract

According to the preparation method of the optical modulation chip, the optical modulation chip and the optical module provided by the invention, the surface of the first substrate is etched to form the second coupling waveguide and the ridge waveguide of the optical modulator; and a third coupling waveguide is formed above the second coupling waveguide. Etching along the top surface of the first substrate to form a second groove and a third groove; and etching along the bottom surface of the second groove to form a first groove. Growing along the ridge waveguide of the optical modulator to form the optical modulator; and etching along the surface of the second substrate to form a first coupling waveguide and an optical demodulator. Etching along the top surface of the second substrate to respectively form a protruding part, a first lap joint part and a second lap joint part; and arranging the protruding part in the first groove, lapping the first lapping part on the surface of the second groove, and lapping the second lapping part on the surface of the third groove to obtain the light modulation chip. According to the optical modulation chip prepared by the invention, the advantages of the two substrates are fully exerted, and the performance of an optical module is improved.

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 modulation chip, an optical modulation chip and an optical module. Background Art

[0002] With the development of new services and application models such as cloud computing, mobile Internet, and video, the advancement of optical communication technology has become increasingly important. In optical communication technology, optical modules, as one of the key components in optical communication equipment, can realize the conversion of optical and electrical signals. In the development of optical communication technology, the data transmission rate of optical modules is required to be continuously improved.

[0003] In a coherent optical module, there are light sources and coherent components. The light source provides light that does not carry data to the coherent component. The coherent component modulates the light that does not carry data to achieve modulation of the optical signal. The coherent component can also demodulate the optical signal. Therefore, multiple functional devices need to be integrated inside the coherent component, and the modulation rate must be guaranteed at the same time. Summary of the invention

[0004] The present disclosure provides a method for preparing an optical modulation chip, an optical modulation chip and an optical module to optimize the performance of coherent components.

[0005] Etching along the surface of the first substrate to form a second coupling waveguide and a ridge waveguide of the optical modulator;

[0006] forming a third coupling waveguide above the second coupling waveguide, and forming a first etch stop layer above the third coupling waveguide;

[0007] Etching along the top surface of the first substrate to the first etch stop layer to form a second groove and a third groove respectively; then etching along the bottom surface of the second groove to form a first groove;

[0008] Growing a ridge waveguide along the optical modulator to form an optical modulator;

[0009] Etching along the surface of the second substrate to form a first coupling waveguide and a partial structure of an optical demodulator;

[0010] forming a second etch stop layer above the first coupling waveguide; and simultaneously, continuing to grow the optical demodulator along the local structure of the optical demodulator;

[0011] forming the optical demodulator; and etching along the top surface of the second substrate to the second etch stop layer to form a protruding portion, a first overlapping portion and a second overlapping portion respectively;

[0012] The protruding portion is arranged in the first groove, the first overlapping portion is overlapped on the surface of the second groove, and the second overlapping portion is overlapped on the surface of the third groove, so as to obtain the light modulation chip.

[0013] In the preparation method of the optical modulator chip, the optical modulator chip and the optical module provided by the present invention, a second coupling waveguide and a ridge waveguide of an optical modulator are formed by etching along the surface of a first substrate; a third coupling waveguide is formed above the second coupling waveguide, and a first etch stop layer is formed above the third coupling waveguide; etching is performed along the top surface of the first substrate to the first etch stop layer to form a second groove and a third groove; then etching is performed along the bottom surface of the second groove to form a first groove; the ridge waveguide of the optical modulator is grown to form an optical modulator; the first coupling waveguide and a local structure of an optical demodulator are formed by etching along the surface of the second substrate; a second etch stop layer is formed above the first coupling waveguide; at the same time, the optical demodulator is continued to grow along the local structure of the optical demodulator to obtain the optical demodulator; and etching is performed along the top surface of the second substrate to the second etch stop layer to form a protruding portion, a first overlapping portion and a second overlapping portion respectively; the protruding portion is arranged in the first groove, the first overlapping portion is overlapped on the surface of the second groove, and the second overlapping portion is overlapped on the surface of the third groove to obtain the optical modulator chip. According to the optical modulation chip obtained by the optical modulation chip preparation method provided by the present disclosure, the light to be modulated is transmitted to the optical modulator in sequence through the first coupling waveguide, the third coupling waveguide, and the second coupling waveguide to modulate the optical signal. The modulated optical signal is output in sequence through the second coupling waveguide, the third coupling waveguide, and the first coupling waveguide. In the optical modulation chip provided by the present disclosure, exemplarily, the first substrate is a thin film lithium niobate-based substrate, and the second substrate is a silicon-based substrate. Since the thin film lithium niobate-based substrate has a high modulation efficiency, an optical modulator is provided on the surface of the first substrate. Since the surface of the silicon-based substrate is easy to integrate various functional devices, an optical demodulator is provided on the surface of the second substrate. The optical modulation chip in the present disclosure is hybrid integrated with the first substrate and the second substrate, and the optical modulator and the optical demodulator are respectively arranged on the surfaces of the first substrate and the second substrate, so as to give full play to the advantages of the two substrates, thereby improving the modulation and demodulation performance of the optical module. At the same time, the transmission of the optical signal between the first substrate and the second substrate is realized through the end face coupler, the first coupling waveguide, and the second coupling waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present disclosure, the following briefly introduces the drawings 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 limitations on 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.

[0015] Figure 1 A partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure;

[0016] Figure 2 A partial structural diagram of a host computer provided according to some embodiments of the present disclosure;

[0017] Figure 3 A structural diagram of an optical module provided according to some embodiments of the present disclosure;

[0018] Figure 4 An exploded view of an optical module provided according to some embodiments of the present disclosure;

[0019] Figure 5 The structure of an optical modulation chip provided according to some embodiments of the present disclosure is Figure 1 ;

[0020] Figure 6 The structure of an optical modulation chip provided according to some embodiments of the present disclosure is Figure 2 ;

[0021] Figure 7 An optical path diagram of an optical modulation chip provided according to some embodiments of the present disclosure;

[0022] Figure 8 A schematic diagram of the working principle of an optical modulation chip provided according to some embodiments of the present disclosure;

[0023] Fig. 9 A structural diagram of an optical modulator provided according to some embodiments of the present disclosure;

[0024] Fig.10 A top view of a light modulator provided according to some embodiments of the present disclosure;

[0025] Fig.11 A schematic diagram of electrical connection between an optical modulator and a modulation driver provided according to some embodiments of the present disclosure;

[0026] Fig.12 A schematic diagram of the relative position relationship between a first coupling waveguide and a second coupling waveguide provided according to some embodiments of the present disclosure;

[0027] Fig.13 A schematic diagram of the structure of a first coupling waveguide provided according to some embodiments of the present disclosure;

[0028] Fig.14 A schematic diagram of the structure of a second coupling waveguide provided according to some embodiments of the present disclosure;

[0029] Fig.15 A schematic diagram of the relative position relationship between a first coupling waveguide, a second coupling waveguide and a third coupling waveguide provided according to some embodiments of the present disclosure;

[0030] Fig.16 A schematic diagram of the structure of a third coupled waveguide provided according to some embodiments of the present disclosure;

[0031] Fig.17 A schematic diagram of the structure of a first optical chip provided according to some embodiments of the present disclosure;

[0032] Fig.18 A schematic diagram of the structure of a second optical chip provided according to some embodiments of the present disclosure;

[0033] Fig.19 A schematic diagram of a preparation process of a first optical chip provided according to some embodiments of the present disclosure;

[0034] Fig. 20 A schematic diagram of the preparation process of a second optical chip provided according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0035] 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 the optical signal is transmitted in the 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 signal that the information processing equipment can recognize and process is an electrical signal. 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 third-coupled waveguides, etc.

[0036] 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.

[0037] 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 .

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Figure 2 1 is a partial structural diagram of a host computer provided 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.

[0044] 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.

[0045] 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 modulation chip 900 and a light source 1100. At this time, the optical module 200 is a coherent optical module.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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 opening 204 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 modulation chip 900 in the optical module 200.

[0050] The upper housing 201 and the lower housing 202 are combined to facilitate the installation of the circuit board 300, the optical modulation chip 900, the light source 1100, etc. into the housing, and the upper housing 201 and the lower housing 202 can encapsulate and protect the above components. In addition, when assembling the circuit board 300, the optical modulation chip 900, the light source 1100, etc., it is convenient to deploy the positioning components, heat dissipation components, and electromagnetic shielding components of these components, which is conducive to automated production.

[0051] In some embodiments, the upper shell 201 and the lower shell 202 are made of metal materials to facilitate electromagnetic shielding and heat dissipation.

[0052] 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, or to release the fixed connection between the optical module 200 and the host computer.

[0053] 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.

[0054] 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), etc. The chips may include microcontroller units (Microcontroller Unit, MCU), laser driver chips, transimpedance amplifiers (Transimpedance Amplifier, TIA), limiting amplifiers (Limiting amplifier), clock and data recovery chips (Clock and Data Recovery, CDR), power management chips, digital signal processing (Digital Signal Processing, DSP) chips.

[0055] 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.

[0056] 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.

[0057] The optical modulation chip 900 itself does not have a light source, and the light source 1100 is used as an external light source of the optical modulation chip 900. The light source 1100 emits light from the side, and the light it emits enters the optical modulation chip 900. The light source 1100 can use a laser box, and the laser box has a laser packaged inside. The laser emits light to generate a laser beam. The light source 1100 is used to provide the emission laser to the optical modulation chip 900. The laser has a good single wavelength characteristic and a good wavelength tuning characteristic, making it the preferred light source for optical modules and even optical fiber transmission. Other types of light, such as LED light, are generally not used in common optical communication systems. Even if such a light source is used in a special optical communication system, the characteristics of the light source and the chip components are greatly different from those of the laser, so that there are great technical differences between the optical module using the laser and the optical module using other light sources. Those skilled in the art generally do not think that these two types of optical modules can give technical inspiration to each other.

[0058] The light emitted by the light source 1100 is light that does not carry data. The light that does not carry data is the light to be modulated. The light to be modulated enters the optical modulation chip 900, and the optical modulation chip 900 modulates it and loads the electrical signal into the light to be modulated to obtain light that carries data, that is, generates a light transmission signal, thereby realizing the transmission of the optical signal; the external light enters the optical modulation chip 900, and the optical modulation chip 900 demodulates it, thereby realizing the reception of the optical signal.

[0059] In some embodiments, the optical modulation chip 900 may be a silicon photonic chip, which has an integrated modulator inside, and the modulator can realize the modulation and demodulation of optical signals. Since silicon photonic chips are easy to etch, other functional devices such as splitters, combiners, mixers, photodetectors, etc. can be integrated inside them to realize more functions. However, the basic characteristics of silicon materials lead to defects such as low modulation efficiency, large capacitance, limited bandwidth, and large optical loss in the realization of optical modulators.

[0060] In some embodiments, the optical modulation chip 900 may be a thin-film lithium niobate chip. Thin-film lithium niobate has characteristics such as linear electro-optical effect. An external electric field causes a linear change in the refractive index in the corresponding direction, so that the light wave transmitted in the medium has adjustable intensity, phase and other information. Therefore, thin-film lithium niobate can be selected as the material of the optical modulator to achieve higher modulation efficiency, etc. However, thin-film lithium niobate material is relatively hard and difficult to etch, so it is difficult to integrate multiple functional devices on its surface. At the same time, the optical loss of thin-film lithium niobate chips is low.

[0061] Figure 5 The structure of an optical modulation chip provided according to some embodiments of the present disclosure is Figure 1 ; Figure 6 The structure of an optical modulation chip provided according to some embodiments of the present disclosure is Figure 2 .like Figure 5 and Figure 6 As shown, in some embodiments of the present disclosure, the optical modulation chip 900 includes a first substrate 910. In some embodiments, the first substrate 910 is a thin-film lithium niobate-based substrate. Exemplarily, the thin-film lithium niobate-based substrate includes a stacked silicon layer, a first silicon oxide layer, and a thin-film lithium niobate layer. Since thin-film niobate has a high modulation efficiency, an optical modulator 911 is formed on the surface of the first substrate 910, and the light to be modulated is modulated by the optical modulator 911.

[0062] The optical modulation chip 900 also includes a second substrate 920, which is arranged opposite to the first substrate 910. In some embodiments, the second substrate 920 is a silicon-based substrate. For example, the silicon-based substrate includes a first silicon layer, a silicon oxide layer, and a second silicon layer that are stacked. Since the silicon-based material is convenient for integrating various functional devices, other functional devices such as an optical demodulator 921 are formed on the surface of the second substrate 920, and the optical signal is demodulated by the optical demodulator 921. For example, the optical demodulator 921 is a photodetector, which can demodulate the optical signal into an electrical signal, thereby realizing the demodulation of the optical signal.

[0063] In some embodiments, in order to achieve transmission of optical signals, an end face coupler 922 and a first coupling waveguide 923 are formed on the surface of the second substrate 920, and a first optical splitter is also formed on the surface of the second substrate 920; a second coupling waveguide 913 is formed on the surface of the first substrate 910. The end face coupler 922 is optically connected to the first coupling waveguide 923, and the first coupling waveguide 923 is optically connected to the second coupling waveguide 913, thereby achieving transmission of optical signals between the surface of the second substrate 920 and the surface of the first substrate 910.

[0064] The light outputted by the light source 1100 that does not carry data, i.e., the light to be modulated, enters the surface of the second substrate 920 through the end coupler 922. The light that does not carry data is decomposed into the local oscillation light and the transmitting end light source by the first optical splitter on the surface of the second substrate 920. The local oscillation light is transmitted to the optical demodulator 921 for coherent demodulation of the optical signal; the transmitting end light source is outputted along the first coupling waveguide 923 until it is coupled to the second coupling waveguide 913, and then enters the optical modulator 911 on the surface of the first substrate 910 to modulate the optical signal.

[0065] In some embodiments, in order to reduce the size of the optical modulation chip 900 and facilitate chip miniaturization, the second substrate 920 includes a protruding portion 924, a first overlapping portion 925 and a second overlapping portion 926 respectively located on both sides of the protruding portion 924; the first substrate 910 includes a first groove 912, a second groove 915 and a third groove 914 respectively located on both sides of the first groove 912. Exemplarily, the protruding portion 924 is protruding relative to the surfaces of the first overlapping portion 925 and the second overlapping portion 926; the first groove 912 is recessed relative to the second groove 915 and the third groove 914.

[0066] Exemplarily, the surfaces of the second groove 915 and the third groove 914 are on the same horizontal line, and the surfaces of the first overlapping portion 925 and the second overlapping portion 926 are on the same horizontal line.

[0067] Exemplarily, the second groove 915 and the third groove 914 are both located above the first groove 912. The first groove 912 is provided for embedding the optical demodulator 921, and the second groove 915 is provided to reduce the coupling distance between the first coupling waveguide 923 and the second coupling waveguide 913. Furthermore, by sinking the second substrate 920 to the surface of the second groove 915 and the third groove 914, the second substrate 920 is close to the first substrate 910, thereby reducing the height of the optical modulation chip 900, and then reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization.

[0068] In some embodiments, since the optical demodulator 921 has a certain height, in the present disclosure, the optical demodulator 921 is disposed in the protrusion 924, the protrusion 924 is embedded in the first groove 912, the first overlap portion 925 overlaps the surface of the second groove 915, and the second overlap portion 926 overlaps the surface of the third groove 914, so that the second substrate 920 is close to the first substrate 910, thereby reducing the height of the optical modulation chip 900, and then reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization. At the same time, the coupling distance between the first coupling waveguide 923 and the second coupling waveguide 913 is shortened, thereby reducing light loss, which is conducive to the transmission of optical signals.

[0069] Exemplarily, the second groove 915 is connected to the first overlap portion 925 by optical matching glue, and the third groove 914 is connected to the second overlap portion 926 by optical matching glue. The inner wall surface of the first groove 912 is also filled with optical matching glue to achieve connection with the protrusion 924.

[0070] In some embodiments, the end coupler 922 is disposed on one side of the optical demodulator 921, and the end coupler 922 is disposed above the second overlapping portion 926; the first coupling waveguide 923 is disposed on the other side of the optical demodulator 921, and the first coupling waveguide 923 is located above the first overlapping portion 925. The end coupler 922 and the first coupling waveguide 923 are respectively located at two different optical ports of the second substrate 920 to achieve transmission of optical signals.

[0071] In an embodiment of the present disclosure, an optical modulator 911 is disposed on the surface of a first substrate 910. Exemplarily, the first substrate 910 is a thin-film lithium niobate-based substrate; an optical demodulator 921 is disposed on the surface of a second substrate 920. Exemplarily, the second substrate 920 is a silicon-based substrate. At the same time, optical signal transmission is achieved through the first coupling waveguide 923 and the second coupling waveguide 913, thereby obtaining a hybrid integrated optical modulation chip. The optical modulation chip 900 of the present disclosure is integrated with two substrates, so that multiple functional devices can be integrated through a silicon-based substrate, and a higher modulation efficiency can be provided through a thin-film lithium niobate-based substrate, thereby making full use of the advantages of the two substrates, optimizing the modulation performance of the optical modulation chip 900, and improving the coherence performance of the optical module.

[0072] In some embodiments, the end coupler 922 is a silicon nitride coupler. In order to achieve the coupling transmission of optical signals between the end coupler 922 and the first coupling waveguide 923, a silicon nitride optical waveguide 927 is provided on one side of the end coupler 922, and a silicon waveguide 927a is provided above the silicon nitride optical waveguide 927. Light enters the end coupler 922, and is coupled to the first coupling waveguide 923 through the coupling transmission of the silicon nitride optical waveguide 927, the silicon waveguide 927a, and the optical waveguide 921a of the optical demodulator 921 in sequence, thereby achieving the optical signal transmission between the end coupler 922 and the first coupling waveguide 923, and transmitting the light to be modulated from the end coupler 922 to the first coupling waveguide 923. The optical waveguide 921a of the optical demodulator 921 is also a silicon waveguide, and the silicon waveguide 927a, the optical waveguide 921a of the optical demodulator 921, and the first coupling waveguide 923 are on the same horizontal plane.

[0073] In some embodiments, a grating is etched on the surface of the second coupling waveguide 913, and a certain proportion of light splitting is achieved through the grating to detect the optical power. When the second coupling waveguide 913 is a thin-film lithium niobate waveguide, it is difficult to etch a grating on the surface of the second coupling waveguide 913 due to the relatively large hardness of the thin-film lithium niobate waveguide. For this reason, a third coupling waveguide 916 is formed above the second coupling waveguide 913, and a grating is etched on the surface of the third coupling waveguide 916 to perform a certain proportion of light splitting, thereby detecting the optical power. Exemplarily, the third coupling waveguide 916 is an amorphous silicon optical waveguide, so that the grating can be formed by etching. The third coupling waveguide 916 is located between the first coupling waveguide 923 and the second coupling waveguide 913. One end of the third coupling waveguide 916 faces the first coupling waveguide 923 to receive the light that does not carry data output by the first coupling waveguide 923. The other end of the third coupling waveguide 916 faces the second coupling waveguide 913 to couple the light that does not carry data into the second coupling waveguide 913.

[0074] In some embodiments, a phase modulator 918b is formed on one side of the optical modulator 911. Exemplarily, the phase modulator 918b is heated by a heating resistor, thereby changing the temperature of one of the modulation arms of the optical modulator 911, and its refractive index changes accordingly, and the phase changes, thereby adjusting the phase difference between the two modulation arms of the optical modulator 911, and then adjusting the working point of the modulator. In some embodiments, in order to effectively heat the phase modulator 918b, the projection area of ​​the phase modulator 918b on the surface of the first substrate 910 is hollowed out to form a hollowed-out area 918c, so as to prevent heat from being dissipated from the surface of the first substrate 910, thereby accumulating heat near the phase modulator 918b, and achieving effective heating of the phase modulator 918b.

[0075] In some embodiments, a welding portion 910 b is formed on the surface of the first groove 912 opposite to the optical demodulator 921 , and the optical demodulator 921 and the welding portion 910 b are welded to each other via welding points, thereby fixing the optical demodulator 921 to the surface of the first groove 912 .

[0076] Figure 7 FIG. 1 is a light path diagram of an optical modulation chip provided according to some embodiments of the present disclosure. Figure 7The figure shows the transmission optical path diagram of the light to be modulated. The light enters the end coupler 922, is transmitted to the silicon waveguide 927a and the optical demodulator 921 through the silicon nitride optical waveguide 927, and a part of the light is retained in the optical demodulator 921 for coherent demodulation after being split, and the other part is transmitted through the optical waveguide 921a of the optical demodulator 921 and coupled to the inside of the first coupling waveguide 923, thereby realizing the optical signal transmission between the end coupler 922 and the first coupling waveguide 923, and transmitting the light to be modulated from the end coupler 922 to the first coupling waveguide 923.

[0077] The light to be modulated continues to be transmitted through the first coupling waveguide 923 to one end of the third coupling waveguide 916, and then coupled and transmitted from the other end of the third coupling waveguide 916 to the second coupling waveguide 913, and is transmitted to the optical modulator 911 through the second coupling waveguide 913 to modulate the optical signal.

[0078] The modulated optical signal returns along the above optical path until it is output through the end face coupler 922 .

[0079] Figure 8 FIG. 1 is a schematic diagram of the working principle of an optical modulation chip provided according to some embodiments of the present disclosure. Figure 8 As shown, in some embodiments of the present disclosure, a second coupling waveguide 913 is formed on the surface of the first substrate 910, and a first coupling waveguide 923 is formed on the surface of the second substrate 920. The coupling of light waves between the first coupling waveguide 923 and the second coupling waveguide 913 is evanescent wave coupling, and the evanescent field of the light wave in the first coupling waveguide 923 is coupled with the evanescent field of the light wave in the second coupling waveguide 913. Based on the evanescent wave coupling principle, the second substrate 920 is mounted on the surface of the first substrate 910 through the evanescent wave coupling mounting technology, thereby obtaining a hybrid integrated optical modulation chip 900.

[0080] An end face coupler 922 is formed on the surface of the second substrate 920, and the end face coupler 922 includes an output optical port 9221, a first input optical port 9222 and a second input optical port 9223. The output optical port 9221 is used to output the modulated optical signal; the first input optical port 9222 is used to receive the light that does not carry data output by the light source 1100, that is, the light to be modulated; the second input optical port 9223 is used to receive the optical signal transmitted by the external optical fiber ribbon, that is, the light to be demodulated.

[0081] In some embodiments, the surface of the second substrate 920 is also integrated with an optical demodulation unit, and the optical demodulation unit includes a plurality of functional devices. Exemplarily, the surface of the second substrate 920 is also respectively integrated with a first beam splitter 9281, a second beam splitter 9282, a third beam splitter 9283, a first mixer 9284, a second mixer 9285, a first detector 9286, and a second detector 9287. Among them, the first detector 9286 is an optical demodulator 921, and the second detector 9287 is used to monitor the optical power of the received optical signal. Exemplarily, the second beam splitter 9282 and the third beam splitter 9283 are polarization beam splitters.

[0082] The light not carrying data output by the light source 1100 enters the surface of the second substrate 920 through the first input light port 9222. The light not carrying data is decomposed by the third spectrometer 9283 into local oscillation light and a transmitting light source. The local oscillation light remains inside the first detector 9286 for coherent demodulation of the optical signal. The transmitting light source is output along the first coupling waveguide 923 and coupled to the second coupling waveguide 913 until it is transmitted to the optical modulator 911. Therefore, in the present disclosure, the local oscillation light remains on the surface of the second substrate 920, while the transmitting light source is transmitted to the surface of the first substrate 910.

[0083] The local oscillator light is split by the third beam splitter 9283 into two optical signals with perpendicular polarization directions, namely, the first TE polarized light and the first TM polarized light; when the external optical signal enters the surface of the second substrate 920, it is also split by the second beam splitter 9282 into two optical signals with perpendicular polarization directions, namely, the second TE polarized light and the second TM polarized light.

[0084] The first TE polarized light and the second TE polarized light are mixed and amplified in the first mixer 9284 to obtain the first mixed light. Exemplarily, the first mixer 9284 can be a 90° optical mixer. The first TM polarized light and the second TM polarized light are mixed and amplified in the second mixer 9285 to obtain the second mixed light. Both the first mixed light and the second mixed light are amplified optical signals. Through coherent detection reception, the first mixed light and the second mixed light are converted into corresponding electrical signals. After removing interference factors such as dispersion, noise, and nonlinearity through digital signal processing, the telecommunication number stream is restored.

[0085] In some embodiments, the light that does not carry data output by the light source 1100, that is, the light to be modulated, enters the surface of the second substrate 920 through the first input light port 9222. The light that does not carry data is decomposed by the first spectrometer 9281 into local oscillator light and a transmitting light source. The transmitting light source is transmitted along the first coupling waveguide 923, coupled to the second coupling waveguide 913 at the light output end of the second substrate 920, and then enters the interior of the optical modulator 911 along the second coupling waveguide 913 to modulate the optical signal.

[0086] In some embodiments, the modulated optical signal, the modulated optical signal output from the modulation electrode is combined by a combiner on the surface of the first substrate 910 to obtain a first polarized light and a second polarized light, the first polarized light and the second polarized light are transmitted along the second coupling waveguide 913 to the surface of the second substrate 920, the first polarized light and the second polarized light are combined by a polarization rotation beam splitter 9288 on the surface of the second substrate 920 to obtain a light transmission signal, the light transmission signal output port 9221 is output to the outside of the second substrate 920, and is transmitted to the outside of the optical module along the external optical fiber ribbon.

[0087] In an embodiment of the present disclosure, modulation and demodulation of optical signals are performed on different substrates respectively. For example, modulation of optical signals is performed on a first substrate 910, and demodulation of optical signals is performed on a second substrate 920, thereby avoiding mutual crosstalk of optical signals during modulation and demodulation, thereby ensuring the quality of modulation and demodulation.

[0088] In the embodiment of the present disclosure, the second substrate 920 is mounted on the surface of the first substrate 910 through the evanescent wave coupling mounting technology to obtain a hybrid integrated optical modulation chip 900. The optical modulation chip 900 can integrate multiple functional devices inside to achieve multifunctionality, and can also have higher modulation efficiency, optimize modulation performance, and improve signal modulation quality.

[0089] In the embodiment of the present disclosure, the light outputted by the light source 1100 that does not carry data enters the surface of the second substrate 920 through the end coupler 922, and the light that does not carry data is decomposed into the local oscillator light and the transmitting end light source by the third spectrometer 9283. Among them, the local oscillator light remains inside the optical demodulator 921 and is used for coherent demodulation of the optical signal; the transmitting end light source is output along the first coupling waveguide 923, coupled to the second coupling waveguide 913 through the third coupling waveguide 916, until it is transmitted to the optical modulator 911, and the optical modulator 911 modulates the optical signal. The modulated optical signal is outputted through the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, and the end coupler 922 in sequence. The end coupler 922 transmits the light to be modulated through the silicon nitride optical waveguide 927 and the silicon waveguide 927a toward the first coupling waveguide 923, the first coupling waveguide 923 transmits the light to be modulated toward the third coupling waveguide 916, the third coupling waveguide 916 transmits the light to be modulated toward the second coupling waveguide 913, and the second coupling waveguide 913 transmits the light to be modulated toward the optical modulator 911. The modulated optical signal is transmitted through the second coupling waveguide 913, the second coupling waveguide 913 transmits the modulated optical signal toward the third coupling waveguide 916, the third coupling waveguide 916 transmits the modulated optical signal toward the first coupling waveguide 923, and the first coupling waveguide 923 transmits the modulated optical signal toward the end coupler 922.

[0090] In some embodiments of the present disclosure, the optical modulator 911 modulates the light to be modulated according to the electrical signal. Exemplarily, the electrical signal is loaded into the light to be modulated, thereby modulating it into an optical signal carrying data. The optical modulator 911 has certain requirements for the amplitude of the received electrical signal, etc. Therefore, the electrical signal will be processed before entering the optical modulator 911. To this end, a modulation driver 918 is also formed on the surface of the first substrate 910. The modulation driver 918 is arranged on one side of the optical modulator 911, and the modulation driver 918 is electrically connected to the optical modulator 911. The modulation driver 918 processes the electrical signal transmitted to the optical modulator 911 and increases the amplitude of the electrical signal so that it meets the requirements of the optical modulator 911. Then, the electrical signal is loaded onto the light to be modulated through the optical modulator 911 to generate an optical transmission signal carrying information.

[0091] In some embodiments, the modulation driver 918 is electrically connected to the optical modulator 911 through the metal layer 918a. Exemplarily, the modulation driver 918 is soldered to the surface of the metal layer 918a by flip-chip, such as by BGA solder balls. In order to shorten the length of the metal layer 918a and improve the high-frequency signal transmission performance, a metal layer is laid along the metal layer at the top of the optical modulator 911 to form the metal layer 918a. The metal layer 918a is laid along the surface where the end of the optical modulator 911 is located, one end of the metal layer 918a is electrically connected to the optical modulator 911, and the other end is electrically connected to the modulation driver 918, thereby realizing the electrical connection between the modulation driver 918 and the optical modulator 911.

[0092] In some embodiments of the present disclosure, the optical modulation chip 900 is disposed on the surface of the circuit board 300. The optical demodulator 921 is a photodetector, which can demodulate the optical signal into an electrical signal, thereby realizing the demodulation of the optical signal. In some embodiments, the electrical signal is also amplified by a transimpedance amplifier. To this end, a transimpedance amplifier 919 is also formed on the surface of the first substrate 910 to amplify the demodulated electrical signal. The transimpedance amplifier 919 is disposed on one side of the optical demodulator 921, and the transimpedance amplifier 919 is electrically connected to the optical demodulator 921.

[0093] Since the optical demodulator 921 is embedded in the first groove 912, the optical demodulator 921 is wrapped in the first groove 912, and it is impossible to lead out the wiring to achieve electrical connection with the transimpedance amplifier 919. To this end, a first via hole 919a is formed along the end of the optical demodulator 921 through the first substrate 910 toward the circuit board 300. Exemplarily, an etched through hole is penetrated along the welding portion 910b toward the surface of the circuit board 300, and the through hole is filled with a metal medium, thereby forming a first via hole 919a. The first via hole 919a penetrates the surface of the first substrate 910, and the first via hole 919a is filled with a metal medium to achieve electrical connection between the optical demodulator 921 and the circuit board 300, that is, the optical demodulator 921 and the circuit board 300 are electrically connected through the first via hole 919a.

[0094] A second via 919b is formed along the bottom surface of the transimpedance amplifier 919 and through the first substrate 910 toward the circuit board 300. Exemplarily, a through-hole is etched along the bottom surface of the transimpedance amplifier 919 toward the circuit board 300, and the through-hole is filled with a metal medium, thereby forming the second via 919b. The second via 919b passes through the surface of the first substrate 910, and the second via 919b is filled with a metal medium to achieve electrical connection between the transimpedance amplifier 919 and the circuit board 300, that is, the transimpedance amplifier 919 and the circuit board 300 are electrically connected through the second via 919b.

[0095] The end of the first via 919a forms a first connection portion on the surface of the circuit board 300, and the end of the second via 919b forms a second connection portion on the surface of the circuit board 300. The first connection portion and the second connection portion are electrically connected, thereby realizing the electrical connection between the optical demodulator 921 and the transimpedance amplifier 919. In some embodiments, the first connection portion and the second connection portion are electrically connected through a trace 919c. Exemplarily, the first connection portion is a first pad, the second connection portion is a second pad, and the first pad and the second pad are electrically connected through a trace 919c, thereby realizing the electrical connection between the optical demodulator 921 and the transimpedance amplifier 919.

[0096] In some embodiments, the first via 919a and the second via 919b are formed by etching a through hole and depositing metal in the through hole. In order to unify the depth of the etched through hole and the thickness of the deposited metal in the two electrical channels and facilitate processing, a fourth groove 917 is also formed on the surface of the first substrate 910, and the TIA 919 is set on the surface of the fourth groove 917. Exemplarily, the transimpedance amplifier 919 is soldered to the surface of the fourth groove 917 by flip-chip, such as by BGA solder balls.

[0097] Exemplarily, when the distance from the fourth groove 917 to the bottom surface of the first substrate 910 is the same as the distance from the first groove 912 to the bottom surface of the first substrate 910, that is, the top surface of the fourth groove 917 is flush with the plane where the top surface of the first groove 912 is located, it can be ensured that the depth of the etched through hole and the thickness of the deposited metal in the two electrical channels are the same, thereby simplifying the processing technology.

[0098] In the present disclosure, the modulation driver 918 and the transimpedance amplifier 919 are disposed on the surface of the first substrate 910, so that the modulation driver 918 and the transimpedance amplifier 919 are integrated inside the optical modulation chip 900, thereby saving the space of the circuit board 300. At the same time, the distance between the modulation driver 918 and the optical modulator 911 can be shortened, and the distance between the optical demodulator 921 and the transimpedance amplifier 919 can be shortened, which is beneficial to signal transmission.

[0099] Of course, in some embodiments of the present disclosure, a modulation driver 918 is provided on the surface of the circuit board 300, and a wire is bonded between the modulation driver 918 and the optical modulator 911. In some embodiments of the present disclosure, a transimpedance amplifier 919 is provided on the surface of the circuit board 300, and then an electrical channel is formed by etching a through hole through the surface of the first substrate 910 at the bottom of the first groove 912 toward the circuit board 300, and the electrical channel realizes the electrical connection between the optical demodulator 921 and the circuit board 300. At the same time, the electrical channel has a pad formed on the surface of the circuit board 300, and the pad is wired to the transimpedance amplifier 919, thereby realizing the electrical connection between the optical demodulator 921 and the transimpedance amplifier 919.

[0100] In some embodiments of the present disclosure, when the optical modulator 911 is a silicon-based modulator, the optical modulator 911 includes a first S modulation electrode, a G modulation electrode and a first S modulation electrode, a ridge waveguide is provided between the first S modulation electrode and the G modulation electrode, and a ridge waveguide is provided between the G modulation electrode and the first S modulation electrode. When working, when the modulation driver 918 is a differential driver, the modulation driver 918 includes a first output end and a second output end, and the first output end and the second output end respectively output a differential signal S+ and a differential signal S-, and the signal amplitude between the two differential signals is Vs. The differential signal S+ and the differential signal S- are respectively applied to the first S modulation electrode and the second S modulation electrode. Since the applied signal amplitudes are the same and the phases are opposite, the changes in the refractive index of the materials on the two arms are opposite, resulting in a phase difference of 2·Vs, and the optical modulation amplitude (OMA) is OMA=Vs-(-Vs)=2Vs.

[0101] Fig. 9 A structural diagram of an optical modulator provided according to some embodiments of the present disclosure; Fig.10FIG. 1 is a top view of an optical modulator provided according to some embodiments of the present disclosure. Fig. 9 and Fig.10 As shown, in some embodiments of the present disclosure, the optical modulator 911 is a thin-film lithium niobate-based modulator, and the optical modulator 911 includes a first ridge waveguide 9111, a second ridge waveguide 9112, and also includes a first differential modulation electrode 9113, a second differential modulation electrode 9114, a third differential modulation electrode 9115, and a fourth differential modulation electrode 9116. The first differential modulation electrode 9113 is located on one side of the first ridge waveguide 9111, the second differential modulation electrode 9114 and the third differential modulation electrode 9115 are located between the other side of the first ridge waveguide 9111 and one side of the second ridge waveguide 9112, and the fourth differential modulation electrode 9116 is located on the other side of the second ridge waveguide 9112. The two ends of the first differential modulation electrode 9113 include a first metal layer M1 and a second metal layer M2, respectively, and the first metal layer M1 and the second metal layer M2 are electrically connected through a through hole VIA. The two ends of the second differential modulation electrode also include a first metal layer and a second metal layer respectively, and the first metal layer and the second metal layer are electrically connected through a through hole. The third differential modulation electrode and the fourth differential modulation electrode are also the same.

[0102] The modulation driver 918 is a differential driver, and includes a first differential output terminal and a second differential output terminal, and the first differential output terminal and the second differential output terminal respectively output a differential signal S+ and a differential signal S-, and the signal amplitude between the two differential signals is Vs. The differential signal S- is transmitted to the second differential modulation electrode and the third differential modulation electrode, respectively, and the differential signal S+ is transmitted to the first differential modulation electrode and the fourth differential modulation electrode, respectively, thereby forming two pairs of differential traveling wave electrodes.

[0103] Fig.11 FIG. 1 is a schematic diagram of electrical connection between an optical modulator and a modulation driver according to some embodiments of the present disclosure. Fig.11 As shown, in some embodiments of the present disclosure, the first differential output terminal of the modulation driver 918 is electrically connected to the first differential modulation electrode 9113 and the fourth differential modulation electrode 9116, respectively, and the second differential output terminal is electrically connected to the second differential modulation electrode 9114 and the third differential modulation electrode 9115, respectively. Then the differential signal received by the first differential modulation electrode 9113 is +Vs, the differential signal received by the second differential modulation electrode 9114 is -Vs, the differential signal received by the third differential modulation electrode 9115 is -Vs, and the differential signal received by the fourth differential modulation electrode 9116 is +Vs. Among them, the first differential modulation electrode 9113 and the second differential modulation electrode 9114 form a pair of differential traveling wave electrodes, and the third differential modulation electrode 9115 and the fourth differential modulation electrode 9116 form another pair of differential traveling wave electrodes.

[0104] At this time, the optical modulation amplitude OMA = Vs-(-Vs)-(-(Vs-(-Vs))) = 4·Vs. It can be seen that when the optical modulator 911 is a thin-film lithium niobate-based modulator and the modulation driver 918 is a differential driver, the optical modulation amplitude OMA is 4·Vs; when the optical modulator 911 is a silicon-based modulator and the modulation driver 918 is a differential driver, the optical modulation amplitude OMA is 2·Vs.

[0105] In the present disclosure, the optical modulator 911 is a thin-film lithium niobate-based modulator, and when the modulation driver 918 is a differential driver, the optical modulation amplitude OMA can be increased. Under the condition of the same driver power, the OMA of the lithium niobate modulator can be increased to 4·Vs. A larger optical modulation amplitude OMA can reduce the bit error rate of the system receiving end, thereby improving the optical receiving performance.

[0106] Fig.12 FIG. 1 is a schematic diagram of the relative position relationship between a first coupling waveguide and a second coupling waveguide provided according to some embodiments of the present disclosure. Fig.12 As shown, in some embodiments of the present disclosure, the first coupling waveguide 923 and the second coupling waveguide 913 are both tapered waveguides. Exemplarily, when the second substrate 920 is a silicon-based substrate, the first coupling waveguide 923 is a silicon optical waveguide; when the first substrate 910 is a thin-film lithium niobate-based substrate, the second coupling waveguide 913 is a lithium niobate optical waveguide; since the refractive index of the silicon optical waveguide is greater than the refractive index of the lithium niobate optical waveguide, in order to ensure that more light is coupled from the silicon optical waveguide to the lithium niobate waveguide, the first coupling waveguide 923 and the second coupling waveguide 913 are both set as gradient waveguides. Exemplarily, the first coupling waveguide 923 and the second coupling waveguide 913 are both tapered waveguides including tapered sections, thereby changing the effective refractive index of each mode, thereby changing the light field distribution, so that more light is coupled from the first coupling waveguide 923 to the second coupling waveguide 913. Exemplarily, the width of the first coupling waveguide 923 gradually decreases from the light input end to the light output end, and the effective refractive index of its mode gradually decreases. The width of the second coupling waveguide 913 gradually increases from the light input end to the light output end, and the effective refractive index of its mode gradually increases, so that more light is coupled from the first coupling waveguide 923 to the second coupling waveguide 913, thereby increasing the coupling efficiency.

[0107] Fig.13 A schematic diagram of the structure of a first coupling waveguide provided according to some embodiments of the present disclosure; Fig.14 FIG. 1 is a schematic diagram of the structure of a second coupling waveguide provided according to some embodiments of the present disclosure. Fig.13 and Fig.14As shown, the widths of the first coupling waveguide 923 and the second coupling waveguide 913 change in opposite directions. The change in the corresponding widths is intended to reduce the effective refractive index of the mode of the first coupling waveguide 923 and increase the effective refractive index of the mode of the second coupling waveguide 913, thereby changing the light field distribution, so that more light is coupled from the first coupling waveguide 923 to the second coupling waveguide 913, thereby increasing the coupling efficiency.

[0108] The cross-section of the first coupling waveguide 923 consists of a rectangular waveguide and a tapered waveguide. The tapered waveguide is a tapered section of the first coupling waveguide 923, which transitions from the rectangular waveguide to the tapered waveguide. The larger width of the rectangular waveguide can increase the coupling efficiency from the end face coupler 922 to the second substrate 920, thereby increasing the optical power on the surface of the second substrate 920; the gradually decreasing width of the tapered waveguide can transfer the light field to the second coupling waveguide 913, so that more light is coupled from the first coupling waveguide 923 to the second coupling waveguide 913.

[0109] The cross-section of the second coupling waveguide 913 has a gradually changing width, and its width increases from the light input end to the light output end, in order to receive more light output by the first coupling waveguide 923 and, at the same time, increase the output optical power of the second coupling waveguide 913 .

[0110] It can be understood that the present disclosure does not limit the specific shapes of the first coupling waveguide 923 and the second coupling waveguide 913, and any shape that allows more light to be coupled from the first coupling waveguide 923 to the second coupling waveguide 913 is within the protection scope of the present disclosure.

[0111] Fig.15 FIG. 1 is a schematic diagram of the relative position relationship between a first coupling waveguide, a second coupling waveguide, and a third coupling waveguide according to some embodiments of the present disclosure. Fig.15As shown, in some embodiments of the present disclosure, a third coupling waveguide 916 is provided between the first coupling waveguide 923 and the second coupling waveguide 913. A grating is etched on the surface of the third coupling waveguide 916 to perform a certain proportion of light splitting, thereby detecting the optical power. One end of the third coupling waveguide 916 faces the first coupling waveguide 923, and the other end faces the second coupling waveguide 913. From a top-down perspective, the first coupling waveguide 923, the third coupling waveguide 916, and the second coupling waveguide 913 are arranged in sequence from top to bottom. The light that does not carry data output from the end coupler 922 is coupled to the surface of the second substrate 920, transmitted along the first coupling waveguide 923, and output from the surface of the second substrate 920, and then coupled to the third coupling waveguide 916, transmitted along the third coupling waveguide 916, and coupled to the second coupling waveguide 913, until it is transmitted to the optical modulator 911 for optical signal modulation. The modulated optical signal is then output from the surface of the second substrate 920 along the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, and the end coupler 922 in sequence, and then transmitted to the outside of the optical module through the external optical fiber ribbon to realize the emission of the optical signal.

[0112] Since the refractive index of the silicon optical waveguide is greater than the refractive index of the lithium niobate optical waveguide, in order to ensure that more light is coupled from the first coupling waveguide 923 to the third coupling waveguide 916, and at the same time, more light is coupled from the third coupling waveguide 916 to the first coupling waveguide 923, the third coupling waveguide 916 includes a first gradient zone 9161 and a second gradient zone 9162, the first gradient zone 9161 faces the first coupling waveguide 923, and the second gradient zone 9162 faces the second coupling waveguide 913. The waveguide width of the first gradient zone 9161 gradually increases from the light input end to the light output end to match the first coupling waveguide 923 whose width gradually decreases from the light input end to the light output end, so that more light is coupled from the first coupling waveguide 923 to the third coupling waveguide 916; the waveguide width of the second gradient zone 9162 gradually decreases from the light input end to the light output end to match the second coupling waveguide 913 whose width gradually increases from the light input end to the light output end, so that more light is coupled from the third coupling waveguide 916 to the second coupling waveguide 913, thereby realizing the coupling of light not carrying data from the first coupling waveguide 923 to the second coupling waveguide 913 until it is transmitted to the optical modulator 911 for optical signal modulation.

[0113] Fig.16 FIG. 1 is a schematic diagram of the structure of a third coupling waveguide provided according to some embodiments of the present disclosure. Fig.16As shown, in some embodiments of the present disclosure, the third coupling waveguide 916 serves as an optical waveguide between the first coupling waveguide 923 and the second coupling waveguide 913, and includes a first gradient zone 9161 and a second gradient zone 9162 connected in sequence, the first gradient zone 9161 faces the first coupling waveguide 923, and the second gradient zone 9162 faces the second coupling waveguide 913. The width change of the first gradient zone 9161 allows more light to be coupled from the first coupling waveguide 923 to the third coupling waveguide 916, and the width change of the second gradient zone 9162 allows more light to be coupled from the third coupling waveguide 916 to the second coupling waveguide 913, thereby completing the coupling of light that does not carry data from the surface of the second substrate 920 to the surface of the first substrate 910, and then realizing the modulation of the optical signal inside the optical modulator 911.

[0114] It can be understood that the present disclosure does not limit the specific shape of the third coupling waveguide 916, and any corresponding shape that can couple light from the first coupling waveguide 923 to the second coupling waveguide 913 is within the protection scope of the present disclosure.

[0115] Based on the optical modulation chip 900 provided in the above embodiment, modulation and demodulation of optical signals can be realized, and the modulation and demodulation of optical signals are performed on two different substrates respectively to avoid crosstalk between optical signals. In some embodiments, the first substrate 910 and the devices on the surface of the first substrate 910 are integrated into the first optical chip 900a, and the second substrate 920 and the devices on the surface of the second substrate 920 are integrated into the second optical chip 900b. The first optical chip 900a and the second optical chip 900b are integrated together to obtain the optical modulation chip 900. The optical modulation chip 900 in the present disclosure integrates two optical chips, thereby fully utilizing the advantages of the two optical chips.

[0116] Fig.17 FIG. 1 is a schematic diagram of the structure of a first optical chip provided according to some embodiments of the present disclosure. Fig.17 As shown, in some embodiments of the present disclosure, the first optical chip 900a includes a first substrate 910. The surface of the first substrate 910 includes a first groove 912, and a second groove 915 and a third groove 914 are respectively formed on both sides of the first groove 912. The first substrate 910 is a thin-film lithium niobate-based substrate, and correspondingly, the first optical chip 900a is a thin-film lithium niobate chip.

[0117] In some embodiments, an optical modulator 911 is formed on the surface of the first substrate 910, a second coupling waveguide 913 is formed on one side of the optical modulator 911, a third coupling waveguide 916 is formed above the second coupling waveguide 913, and the light to be modulated is sequentially transmitted to the optical modulator 911 through the third coupling waveguide 916 and the second coupling waveguide 913 to modulate the optical signal. The modulated optical signal is sequentially transmitted through the second coupling waveguide 913 and the third coupling waveguide 916, so that the first optical chip 900a is output.

[0118] In some embodiments, a phase modulator 918b is formed on one side of the optical modulator 911. By heating the phase modulator 918b, the temperature of one of the modulation arms of the optical modulator 911 is changed, and its refractive index changes accordingly, and the phase changes, thereby adjusting the phase difference between the two modulation arms of the optical modulator 911, and then adjusting the working point of the modulator. In some embodiments, in order to effectively heat the phase modulator 918b, the projection area of ​​the phase modulator 918b on the surface of the first substrate 910 is hollowed out to form a hollowed-out area 918c, so as to prevent heat from being dissipated from the surface of the first substrate 910, so that the heat is accumulated near the phase modulator 918b, and the phase modulator 918b is effectively heated.

[0119] In some embodiments, a modulation driver 918 is further formed on the surface of the first substrate 910. The modulation driver 918 is disposed on one side of the optical modulator 911 and is electrically connected to the optical modulator 911. The modulation driver 918 processes the electrical signal transmitted to the optical modulator 911 and increases the amplitude of the electrical signal to meet the requirements of the optical modulator 911. The electrical signal is then loaded onto the light to be modulated through the optical modulator 911 to generate an optical emission signal carrying information.

[0120] In some embodiments, the modulation driver 918 is electrically connected to the optical modulator 911 through a metal layer 918a. In order to shorten the length of the metal layer 918a and improve the high-frequency signal transmission performance, a metal layer is laid along the metal layer at the top of the optical modulator 911 to form the metal layer 918a. The metal layer 918a is laid along the surface where the end of the optical modulator 911 is located, and one end of the metal layer 918a is electrically connected to the optical modulator 911, and the other end is electrically connected to the modulation driver 918, thereby realizing the electrical connection between the modulation driver 918 and the optical modulator 911.

[0121] In some embodiments, a transimpedance amplifier 919 is further formed on the surface of the first substrate 910 to amplify the demodulated electrical signal. The transimpedance amplifier 919 is disposed on one side of the optical demodulator 921, and the two are electrically connected.

[0122] Since the optical demodulator 921 is embedded in the first groove 912, the optical demodulator 921 is wrapped in the first groove 912, and it is impossible to lead out the wiring to achieve electrical connection with the transimpedance amplifier 919. To this end, a through hole is etched along the projection area of ​​the optical demodulator 921 on the surface of the first groove 912 toward the surface of the circuit board 300 to form a first via hole 919a. Exemplarily, the first via hole 919a penetrates the surface of the first substrate 910, and the first via hole 919a is filled with a metal medium to achieve electrical connection between the optical demodulator 921 and the circuit board 300, that is, the optical demodulator 921 and the circuit board 300 are electrically connected through the first via hole 919a. At the same time, a through hole is etched through the surface of the first substrate 910 where the transimpedance amplifier 919 is located toward the surface of the circuit board 300 to form a second via hole 919b. Exemplarily, the second via 919b passes through the surface of the first substrate 910 and is filled with a metal medium to achieve electrical connection between the transimpedance amplifier 919 and the circuit board 300, that is, the transimpedance amplifier 919 and the circuit board 300 are electrically connected through the second via 919b.

[0123] The end of the first via 919a forms a first connection portion on the surface of the circuit board 300, and the end of the second via 919b forms a second connection portion on the surface of the circuit board 300. The first connection portion and the second connection portion are electrically connected, thereby realizing the electrical connection between the optical demodulator 921 and the transimpedance amplifier 919. In some embodiments, the first connection portion and the second connection portion are electrically connected through a trace 919c. Exemplarily, the first connection portion is a first pad, the second connection portion is a second pad, and the first pad and the second pad are electrically connected through a trace 919c, thereby realizing the electrical connection between the optical demodulator 921 and the transimpedance amplifier 919.

[0124] In some embodiments, the first via hole 919a and the second via hole 919b are formed by etching a through hole and depositing metal in the through hole. In order to unify the depth of the etched through hole and the thickness of the deposited metal in the two electrical channels and facilitate processing, a fourth groove 917 is further formed on the surface of the first substrate 910, and the TIA 919 is disposed on the surface of the fourth groove 917.

[0125] Exemplarily, when the distance from the fourth groove 917 to the bottom surface of the first substrate 910 is the same as the distance from the first groove 912 to the bottom surface of the first substrate 910, the depth of the etched through hole and the thickness of the deposited metal in the two electrical channels can be ensured to be the same, thereby simplifying the processing technology.

[0126] Fig.18 FIG. 1 is a schematic diagram of the structure of a second optical chip provided according to some embodiments of the present disclosure. Fig.18As shown, in some embodiments of the present disclosure, the second optical chip 900b includes a second substrate 920. The second substrate 920 is a silicon-based substrate, and correspondingly, the second optical chip 900b is a silicon optical chip.

[0127] The second substrate 920 includes a protruding portion 924, a first overlapping portion 925 and a second overlapping portion 926 respectively located on both sides of the protruding portion 924. In some embodiments, the protruding portion 924 is embedded in the first groove 912, the first overlapping portion 925 overlaps the surface of the second groove 915, and the second overlapping portion 926 overlaps the surface of the third groove 914, so that the second substrate 920 is close to the first substrate 910, thereby reducing the height of the optical modulation chip 900, and then reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization.

[0128] In some embodiments, a light demodulator 921 is disposed in the protrusion 924. The light demodulator 921 is embedded in the first groove 912. A welding portion 910b is formed on the surface of the first groove 912 opposite to the light demodulator 921, and the end of the light demodulator 921 is welded to the welding portion 910b through a welding point, thereby fixing the light demodulator 921 to the surface of the first groove 912.

[0129] In some embodiments, in order to achieve transmission of optical signals, an end face coupler 922 and a first coupling waveguide 923 are formed on the surface of the second substrate 920, and a first optical splitter is also formed on the surface of the second substrate 920; a second coupling waveguide 913 is formed on the surface of the first substrate 910. The end face coupler 922 is optically connected to the first coupling waveguide 923, and the first coupling waveguide 923 is optically connected to the second coupling waveguide 913, thereby achieving transmission of optical signals between the surface of the second substrate 920 and the surface of the first substrate 910.

[0130] Exemplarily, the end coupler 922 is a silicon nitride coupler. In order to achieve optical signal coupling transmission between the end coupler 922 and the first coupling waveguide 923, a silicon nitride optical waveguide 927 is provided on one side of the end coupler 922, and a silicon waveguide 927a is provided above the silicon nitride optical waveguide 927. Light enters the end coupler 922, and is coupled to the first coupling waveguide 923 through the coupling transmission of the silicon nitride optical waveguide 927, the silicon waveguide 927a, and the optical waveguide 921a of the optical demodulator 921 in sequence, thereby achieving optical signal transmission between the end coupler 922 and the first coupling waveguide 923, and transmitting the light to be modulated from the end coupler 922 to the first coupling waveguide 923.

[0131] In the embodiment of the present disclosure, the protrusion 924 of the first optical chip 900a is embedded in the first groove 912, the first overlap portion 925 overlaps the surface of the second groove 915, and the second overlap portion 926 overlaps the surface of the third groove 914, so that the second optical chip 900b is close to the first optical chip 900a, thereby reducing the height of the optical modulation chip 900, and then reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization. At the same time, the coupling distance between the first coupling waveguide 923 and the second coupling waveguide 913 is shortened, thereby reducing light loss, which is conducive to the transmission of optical signals.

[0132] In the embodiment of the present disclosure, the light to be modulated enters the second optical chip 900b from the corresponding optical port of the end coupler 922, and is transmitted to the first optical chip 900a through the silicon nitride optical waveguide 927, the silicon waveguide 927a, the optical waveguide 921a of the optical demodulator 921, the first coupling waveguide 923, the third coupling waveguide 916, and the second coupling waveguide 913 in sequence, and reaches the optical modulator 911 for modulation of the optical signal. The modulated optical signal passes through the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, the silicon nitride optical waveguide 927 in sequence, and then is output from the first optical chip 900a through the end coupler 922.

[0133] In the embodiment of the present disclosure, the details of the hybrid integration of the first optical chip 900a and the second optical chip 900b can be referred to in detail. Figure 5 The specific implementation process of the optical modulation chip 900 shown in the embodiment.

[0134] In some embodiments of the present disclosure, the preparation process of the optical modulation chip 900 includes:

[0135] The second coupling waveguide 913 and the ridge waveguide of the optical modulator 911 are formed by etching along the surface of the first substrate 910. A third coupling waveguide 916 is formed above the second coupling waveguide 913, and a first etch stop layer is formed above the third coupling waveguide 916. Etching is performed along the top surface of the first substrate 910 to the first etch stop layer to form a second groove 915 and a third groove 914, respectively. Then, etching is performed along the bottom surface of the second groove 915 to form a first groove 912. The optical modulator 911 is formed by growing along the ridge waveguide of the optical modulator.

[0136] The first coupling waveguide 923 and the local structure of the optical demodulator are formed by etching along the surface of the second substrate 920. A second etching stop layer is formed above the first coupling waveguide 923; at the same time, the optical demodulator 921 is continuously grown along the local structure of the optical demodulator to form the optical demodulator 921; and etching is performed along the top surface of the second substrate 920 to the second etching stop layer to form a protruding portion 924, a first overlapping portion 925, and a second overlapping portion 926, respectively.

[0137] The protruding portion 924 is disposed in the first groove 912 , the first overlapping portion 925 is overlapped on the second groove 915 , and the second overlapping portion 926 is overlapped on the third groove 914 , so as to obtain the optical modulation chip 900 .

[0138] In some embodiments, a phase modulator 918b is formed on one side of the ridge waveguide when the second coupling waveguide 913 and the ridge waveguide of the optical modulator are formed by etching along the surface of the first substrate 910. When the optical modulator is formed by growing along the ridge waveguide of the optical modulator, a hollow region 918c is formed on the first substrate in a region corresponding to the phase modulator 918b.

[0139] In some embodiments, when the second etch stop layer is formed above the first coupling waveguide 923, a silicon nitride optical waveguide 927, a silicon waveguide 927a, and an end coupler 922 are respectively formed on one side of the optical demodulator.

[0140] In some embodiments, a welding portion 910 b is formed on the surface of the first groove 912 ; an end of the optical demodulator 921 is fixedly connected to the welding portion 910 b to fix the optical demodulator 921 to the surface of the first groove 912 .

[0141] In some embodiments, a metal layer 918a is laid along the top of the optical modulator 911, one end of the metal layer 918a is electrically connected to the optical modulator 911, and the other end is electrically connected to the modulation driver 918, thereby achieving electrical connection between the modulation driver 918 and the optical modulator 911.

[0142] In some embodiments, a fourth groove 917 is formed by etching along the bottom surface of the first substrate 910 , and a transimpedance amplifier 919 is formed on the surface of the fourth groove 917 . The transimpedance amplifier 919 is electrically connected to the optical demodulator 921 .

[0143] In some embodiments of the present disclosure, the preparation process of the optical modulation chip 900 may include preparing the first optical chip 900a and the second optical chip 900b separately, and then mixing and integrating the two. In some embodiments, the optical modulation chip 900 is obtained based on the evanescent wave coupling passive mounting technology. Since the evanescent wave coupling passive mounting technology is adopted, the preparation of the first optical chip 900a and the second optical chip 900b can be carried out simultaneously.

[0144] Fig.19 FIG. 1 is a schematic diagram of a preparation process of a first optical chip according to some embodiments of the present disclosure. Fig.19 As shown, in some embodiments of the present disclosure, the first optical chip 900a is a thin-film lithium niobate chip.

[0145] In some embodiments, the preparation process of the first optical chip 900a includes the following steps:

[0146] S110: preparing a first substrate.

[0147] Exemplarily, the first substrate 910 is a thin-film lithium niobate-based substrate, and the first substrate 910 includes a silicon layer, a silicon oxide layer, and a thin-film lithium niobate layer from bottom to top. The silicon oxide layer is an intermediate insulating buried layer, which can achieve full dielectric isolation between the first substrate 910 and the device, thereby optimizing the performance of the device.

[0148] S120: growing along the surface of the thin-film lithium niobate layer of the first substrate to form a phase modulator, a ridge waveguide of the optical modulator, and a second coupling waveguide respectively.

[0149] In some embodiments, etching is performed on the surface of the thin film lithium niobate layer of the first substrate to form the phase modulator 918b, the ridge waveguide of the optical modulator 911, and the second coupling waveguide 913. The ridge waveguide of the optical modulator 911 includes a first ridge waveguide 9111 and a second ridge waveguide 9112.

[0150] S130: Continue to deposit a silicon oxide layer on the surface of the silicon oxide layer of the first substrate, and grow a first metal layer M1 on the surface of the ridge waveguide of the optical modulator.

[0151] In some embodiments, a layer of silicon oxide is deposited on the current surface to form the first metal layer M1 of the light modulator 911, and then a silicon oxide layer of a certain thickness is deposited, and chemical mechanical polishing is used to thin and polish the surface.

[0152] S140: Growing along the current surface to form a third coupling waveguide and an etching stop layer.

[0153] In some embodiments, a layer of amorphous silicon is deposited on the surface, and a single electron beam exposure is used to process the third coupling waveguide 916. Exemplarily, the third coupling waveguide 916 is located obliquely above the second coupling waveguide 913. Then, a certain thickness of silicon oxide is deposited and a first etch stop layer 901 is deposited on top, and the first etch stop layer 901 is located above the third coupling waveguide 916.

[0154] S150: Etching along the current surface to form a second groove, a third groove, a first groove and a fourth groove respectively.

[0155] Etching is performed along the surface to the first etch stop layer 901, and wet etching is used to remove the first etch stop layer 901, thereby forming a second groove 915 and a third groove 914, and etching is continued downward to a certain height along the surface where the second groove 915 is located to form a first groove 912. A fourth groove 917 is formed by etching downward along the surface of the first substrate 910 on one side of the first groove 912.

[0156] Exemplarily, the second groove 915 and the third groove 914 are respectively disposed on both sides of the first groove 912. The first groove 912 is used to embed the optical demodulator 921. The second groove 915 and the third groove 914 are respectively connected to the first overlapping portion 925 and the second overlapping portion 926 in the second optical chip 900b.

[0157] Exemplarily, the arrangement of the first groove 912, the second groove 915, and the third groove 914 is conducive to bringing the second optical chip 900b close to the first optical chip 900a, thereby reducing the size of the optical modulation chip 900, which is conducive to the miniaturization of the chip. At the same time, the arrangement of the second groove 915 is used to shorten the coupling distance between the third coupling waveguide 916 and the corresponding coupling waveguide in the second optical chip, which is conducive to the transmission of optical signals.

[0158] Exemplarily, the surface of the fourth groove 917 is used to set the transimpedance amplifier 919. The top surface of the fourth groove 917 is flush with the plane where the top surface of the first groove 912 is located. The transimpedance amplifier 919 is soldered to the surface of the fourth groove 917 by flip-chip bonding.

[0159] In some embodiments, a via hole is also etched upward along the first metal layer M1 of the optical modulator 911. In some embodiments, a projection area of ​​the phase modulator 918b on the first substrate 910 is hollowed out to form a hollowed-out area 918c.

[0160] S160: Prepare a second metal layer of the optical modulator, and then lay a metal layer that electrically connects the optical modulator and the modulation driver; and prepare a first via hole and a second via hole at the same time.

[0161] In some embodiments, vias VIA and a second metal layer M2 are grown along the first metal layer M1 to prepare the optical modulator 911. At the same time, metal layer 918a is formed along the second metal layer M2 toward the right. The optical modulator 911 is electrically connected to the modulation driver 918 through the metal layer 918a. The modulation driver 918 is soldered to the surface of the metal layer 918a by flip-chip.

[0162] In some embodiments, holes are drilled downward along the first groove 912 and the fourth groove 917 to form a first via hole 919 a and a second via hole 919 b , respectively.

[0163] After the above steps, the first optical chip 900a can be prepared.

[0164] Fig. 20 FIG. 1 is a schematic diagram of a preparation process of a second optical chip according to some embodiments of the present disclosure. Fig. 20 As shown, in some embodiments of the present disclosure, the second optical chip 900b is a silicon photonic chip.

[0165] In some embodiments, the preparation process of the second optical chip 900b includes the following steps:

[0166] S110: preparing a second substrate.

[0167] Illustratively, the second substrate 920 is a silicon-based substrate, and the first substrate 910 includes, from bottom to top, a first silicon layer, a silicon oxide layer, and a second silicon layer.

[0168] The silicon oxide layer is an intermediate insulating buried layer, which can achieve full dielectric isolation between the second substrate 920 and the device, thereby optimizing the performance of the device.

[0169] S220: Growing a first coupling waveguide and various functional devices along the surface of the second silicon layer of the second substrate.

[0170] In some embodiments, a first coupling waveguide 923 is etched on the surface of the second silicon layer of the second substrate, and various functional devices are formed by etching at the same time. The functional devices include the first splitter 9281, the second splitter 9282, the third splitter 9283, the first mixer 9284, the second mixer 9285 and other devices mentioned above.

[0171] At the same time, a ridge waveguide of the optical demodulator 921 is etched on the surface of the second silicon layer of the second substrate, and an absorber in the optical demodulator 921 is grown on the surface of the ridge waveguide.

[0172] S230: Continue to deposit silicon oxide along the surface of the silicon oxide layer of the second substrate, and manufacture an end face coupler and a silicon nitride optical waveguide.

[0173] In some embodiments, a layer of silicon oxide is deposited on the surface of the silicon oxide layer of the second substrate, polished, and then a layer of silicon nitride is deposited, and the surface of the silicon nitride layer is etched to form an end coupler 922, a silicon nitride optical waveguide 927, and a silicon waveguide 927a, and then a certain thickness of silicon oxide is deposited on the surface. Exemplarily, the end coupler 922 is a silicon nitride end coupler.

[0174] S240: Depositing and forming an etching stop layer along the current surface, and manufacturing a first metal electrode layer of each photodetector.

[0175] In some embodiments, a layer of silicon oxide is deposited on the current surface, and a second etch stop layer 902 is formed, and at the same time, a first metal electrode layer of the optical demodulator 921 and a via hole between the first metal electrode layer and the second metal electrode layer are fabricated.

[0176] S250: Fabricate a second metal electrode layer of each photodetector.

[0177] In some embodiments, silicon oxide is deposited to a certain thickness to form a second metal electrode layer for the optical demodulator 921 , thereby achieving the fabrication of the optical demodulator 921 .

[0178] S260: etching to form a third recessed portion and a fourth recessed portion.

[0179] In some embodiments, etching is performed from the surface until the second etch stop layer 902 is etched to form a first overlap portion 925 and a second overlap portion 926 on both sides. Then, the second etch stop layer 902 is removed. When the first overlap portion 925 and the second overlap portion 926 are formed, the protrusion 924 is also formed.

[0180] In some embodiments, an end of the optical demodulator 921 is connected to the welding portion 910 b , thereby fixing the optical demodulator 921 on the surface of the first groove 912 .

[0181] After the above steps, the second optical chip 900b can be prepared.

[0182] In the embodiment of the present disclosure, according to the first optical chip 900a and the second optical chip 900b prepared as above, the protrusion 924 of the first optical chip 900a is embedded in the first groove 912, the first overlapping portion 925 overlaps the surface of the second groove 915, and the second overlapping portion 926 overlaps the surface of the third groove 914, so that the second optical chip 900b is close to the first optical chip 900a, thereby reducing the height of the optical modulation chip 900, and then reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization. At the same time, the coupling distance between the first coupling waveguide 923 and the second coupling waveguide 913 is shortened, thereby reducing light loss, which is conducive to the transmission of optical signals. In the embodiment of the present disclosure, the light to be modulated enters the second optical chip 900b from the corresponding optical port of the end coupler 922, and is transmitted to the first optical chip 900a through the silicon nitride optical waveguide 927, the silicon waveguide 927a, the optical waveguide 921a of the optical demodulator 921, the first coupling waveguide 923, the third coupling waveguide 916, and the second coupling waveguide 913, and reaches the optical modulator 911 for modulation of the optical signal. The modulated optical signal is sequentially transmitted through the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, the optical waveguide 921a of the optical demodulator 921, the silicon waveguide 927a, and the silicon nitride optical waveguide 927, and then output from the first optical chip 900a through the end coupler 922.

[0183] The optical modulation chip provided by the present disclosure includes a first substrate and a second substrate arranged opposite to each other. The first substrate includes a first groove, and a second groove and a third groove are formed on both sides of the first groove respectively. An optical modulator is provided on the surface of the first substrate for modulating an optical signal. A second coupling waveguide is formed on one side of the optical modulator, and the second coupling waveguide is arranged below the second groove. The second coupling waveguide is used to receive the light to be modulated, and transmit the light to be modulated to the optical modulator to modulate the optical signal. The second substrate includes a protruding portion, a first overlapping portion and a second overlapping portion respectively located on both sides of the protruding portion, the protruding portion is embedded in the first groove, the first overlapping portion overlaps the surface of the second groove, and the second overlapping portion overlaps the surface of the third groove, thereby realizing the connection between the first substrate and the second substrate. An optical demodulator is provided on the surface of the second substrate, and the optical demodulator is arranged in the protruding portion for demodulating an optical signal. An end face coupler is formed on one side of the optical demodulator, and the end face coupler is arranged above the second overlapping portion. The end face coupler is used to receive the light to be modulated and continue to transmit the light to be modulated. A first coupling waveguide is formed on the other side of the optical demodulator. The first coupling waveguide is arranged above the first overlap portion. One end of the first coupling waveguide is optically connected to the end coupler, and the other end is optically connected to the second coupling waveguide to receive the light to be modulated output by the end coupler, and transmit the light to be modulated to the second coupling waveguide. According to the optical modulation chip provided by the present disclosure, the light to be modulated is transmitted to the optical modulator in sequence through the end coupler, the optical waveguide of the optical demodulator, the first coupling waveguide, and the second coupling waveguide to modulate the optical signal. The modulated optical signal is output in sequence through the second coupling waveguide, the first coupling waveguide, and the end coupler. In the optical modulation chip provided by the present disclosure, exemplarily, the first substrate is a thin film lithium niobate-based substrate, and the second substrate is a silicon-based substrate. Since the thin film lithium niobate-based substrate has a higher modulation efficiency, an optical modulator is provided on the surface of the first substrate. Since the surface of the silicon-based substrate is easy to integrate various functional devices, an optical demodulator is provided on the surface of the second substrate. The optical modulation chip in the present disclosure is hybrid integrated with a first substrate and a second substrate, and an optical modulator and an optical demodulator are respectively arranged on the surface of the first substrate and the second substrate, so as to give full play to the advantages of the two substrates, thereby improving the modulation and demodulation performance of the optical module. At the same time, the transmission of optical signals between the first substrate and the second substrate is realized through the end face coupler, the first coupling waveguide, and the second coupling waveguide.

[0184] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be thought of by any person skilled in the art within the technical scope disclosed in the present disclosure should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A method for preparing an optical modulation chip, characterized in that: include: Etching along the surface of the first substrate to form a second coupling waveguide and a ridge waveguide of the optical modulator; forming a third coupling waveguide above the second coupling waveguide, and forming a first etch stop layer above the third coupling waveguide; Etching along the top surface of the first substrate to the first etch stop layer to form a second groove and a third groove respectively; then etching along the bottom surface of the second groove to form a first groove; Growing a ridge waveguide along the optical modulator to form an optical modulator; Etching along the surface of the second substrate to form a first coupling waveguide and a partial structure of an optical demodulator; forming a second etch stop layer above the first coupling waveguide; and simultaneously, continuing to grow the optical demodulator along the local structure of the optical demodulator; forming the optical demodulator; and etching along the top surface of the second substrate to the second etch stop layer to form a protruding portion, a first overlapping portion and a second overlapping portion respectively; The protruding portion is arranged in the first groove, the first overlapping portion is overlapped on the surface of the second groove, and the second overlapping portion is overlapped on the surface of the third groove, so as to obtain the light modulation chip.

2. The method for preparing the optical modulation chip according to claim 1, characterized in that: When etching along the surface of the first substrate to form the second coupling waveguide and the ridge waveguide of the optical modulator, a phase modulator is formed on one side of the ridge waveguide of the optical modulator; When the optical modulator is formed by growing the ridge waveguide of the optical modulator, a hollow region is formed in a region corresponding to the phase modulator on the first substrate.

3. The method for preparing the optical modulation chip according to claim 1, characterized in that: When the second etching stop layer is formed above the first coupling waveguide, a silicon nitride optical waveguide and an end face coupler are respectively formed on one side of the optical demodulator.

4. The method for preparing the optical modulation chip according to claim 1, characterized in that: A welding portion is formed on the surface of the first groove, and an end of the optical demodulator is fixedly connected to the welding portion to fix the optical demodulator to the surface of the first groove.

5. The method for preparing the optical modulation chip according to claim 1, characterized in that: Laying a metal layer along the top of the optical modulator, one end of the metal layer is electrically connected to the optical modulator, and the other end is electrically connected to a modulation driver, so as to realize electrical connection between the modulation driver and the optical modulator; A fourth groove is formed by etching along the bottom surface of the first substrate, and a transimpedance amplifier is formed on the surface of the fourth groove.

6. An optical modulation chip, characterized in that: A light modulation chip prepared by the method for preparing a light modulation chip according to any one of claims 1 to 5.

7. The optical modulation chip according to claim 6, characterized in that: include: A first substrate comprises a first groove, wherein a second groove and a third groove are respectively formed on both sides of the first groove; An optical modulator, disposed on the surface of the first substrate, for modulating an optical signal; a second coupling waveguide, disposed at one side of the optical modulator and below the second groove, the second coupling waveguide being used to receive the light to be modulated and transmit the light to be modulated to the optical modulator; The second substrate comprises a protruding portion, a first overlapping portion and a second overlapping portion, wherein the protruding portion is embedded in the first groove, the first overlapping portion overlaps the surface of the second groove, and the second overlapping portion overlaps the surface of the third groove; An optical demodulator, disposed on the surface of the second substrate and in the protruding portion, for demodulating an optical signal; An end coupler, disposed on one side of the optical demodulator and above the second overlapping portion, for receiving and outputting the light to be modulated; The first coupling waveguide is arranged on the other side of the optical demodulator and above the first overlapping portion, one end of which is optically connected to the end face coupler, and the other end of which is optically connected to the second coupling waveguide, and is used to receive the light to be modulated output by the end face coupler and transmit the light to be modulated to the second coupling waveguide.

8. The optical modulation chip according to claim 6, characterized in that: The optical modulation chip is electrically connected to the circuit board; A first via hole is formed along the end of the optical demodulator and passes through the first substrate toward the circuit board to electrically connect the optical demodulator and the circuit board; A transimpedance amplifier is provided on the surface of the first substrate, and a second via hole is formed along the bottom surface of the transimpedance amplifier and penetrates the first substrate toward the circuit board to electrically connect the transimpedance amplifier with the circuit board; The first via hole forms a first connection portion on the surface of the circuit board, and the second via hole forms a second connection portion on the surface of the circuit board; the optical demodulator is connected to the transimpedance amplifier through the connection between the first connection portion and the second connection portion.

9. The optical modulation chip according to claim 6, characterized in that: The optical modulator includes a first ridge waveguide, a second ridge waveguide, a first differential modulation electrode, a second differential modulation electrode, a third differential modulation electrode and a fourth differential modulation electrode; The first differential modulation electrode is located on one side of the first ridge waveguide, the second differential modulation electrode and the third differential modulation electrode are located between the first ridge waveguide and the second ridge waveguide, and the fourth differential modulation electrode is located on one side of the second ridge waveguide; A modulation driver is provided on one side of the optical modulator, and a first output end of the modulation driver is electrically connected to the first differential modulation electrode and the fourth differential modulation electrode respectively, and a second output end of the modulation driver is electrically connected to the second differential modulation electrode and the third differential modulation electrode respectively.

10. An optical module, characterized in that: include: Circuit boards; An optical modulation chip is electrically connected to the circuit board, and the optical modulation chip includes the optical modulation chip described in any one of claims 6-9.

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