Optical module

Abstract

An optical module (200) comprises a circuit board (300) and an optical modulation chip (900). The optical modulation chip (900) comprises a first substrate (910), an optical modulator (911), a second coupled waveguide (913); and a modulation driver (918) is formed on the other side of the optical modulator (911). A transimpedance amplifier (919) is further provided on a surface of the first substrate (910). An optical demodulator (921) is provided on a surface of a second substrate (920), and a first coupled waveguide (923) is formed on one side of the optical demodulator (921). Since the optical demodulator (911) is enclosed in a first recess (912), in order to electrically connect the optical demodulator (921) to the transimpedance amplifier (919), a first via (919a) that runs through the first substrate (910) in a direction from an end of the optical demodulator (912) to the circuit board (300) is formed to electrically connect the optical demodulator (921) to the circuit board (300). A second via (919b) that runs through the first substrate (910) in a direction from a bottom surface of the transimpedance amplifier (919) to the circuit board (300) is formed to electrically connect the transimpedance amplifier (919) to the circuit board (300) and thus electrically connect the light demodulator (921) to the transimpedance amplifier (919).

Description

optical modules

[0001] This application claims the priority of application number 202311258515.7 filed with the China Patent Office on September 27, 2023; the priority of application number 202311258609.4 filed with the China Patent Office on September 27, 2023; the priority of application number 202311267674.3 filed with the China Patent Office on September 27, 2023; the priority of application number 202311269219.7 filed with the China Patent Office on September 27, 2023; the priority of application number 202311267645.7 filed with the China Patent Office on September 27, 2023; all of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the field of optical fiber communication technology, and in particular to an optical module. Background Art

[0003] With the development of new services and applications such as cloud computing, mobile internet, and video, advances in optical communication technology are becoming increasingly important. As a key component in optical communication equipment, optical modules enable photoelectric signal conversion. As optical communication technology evolves, the data transmission rate of these modules continues to increase.

[0004] A coherent optical module includes a light source and a coherent component. The light source provides data-free light to the coherent component, which modulates the data-free light to achieve optical signal modulation. The coherent component can also demodulate the optical signal. Therefore, the coherent component needs to integrate multiple functional devices while ensuring the modulation rate.

[0005] Summary of the Invention

[0006] The present disclosure provides an optical module, comprising: a circuit board; and an optical modulation chip electrically connected to the circuit board, wherein the optical modulation chip comprises:

[0007] A first substrate includes a first groove; an optical modulator is provided on the surface of the first substrate and is configured to modulate the light to be modulated according to the electrical signal; a second coupling waveguide is provided on one side of the optical modulator and is configured to transmit the light to be modulated to the optical modulator; a modulation driver is provided on the other side of the optical modulator, is electrically connected to the optical modulator, and is configured to process the electrical signal; a transimpedance amplifier is provided on the surface of the first substrate; a second substrate is at least partially embedded in the first groove; an optical demodulator is provided on the second substrate and is wrapped by the first groove and is configured to demodulate the optical signal; the optical demodulator is provided on the transimpedance amplifier On one side of the transimpedance amplifier, the optical demodulator is electrically connected to the transimpedance amplifier; a first coupling waveguide is provided on one side of the optical demodulator, optically connected to the second coupling waveguide, and configured to transmit the light to be modulated to the second coupling waveguide; wherein, along the direction from the end of the optical demodulator to the circuit board, a first via hole is formed through the first substrate to electrically connect the optical demodulator and the circuit board; along the direction from the bottom surface of the transimpedance amplifier to the circuit board, a second via hole is formed through the first substrate to electrically connect the transimpedance amplifier and the circuit board; the first via hole and the second via hole are electrically connected through a trace in the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] To more clearly illustrate the technical solutions of the present disclosure, the following briefly describes the drawings used in some embodiments of the present disclosure. Obviously, the drawings described below are merely illustrations of some embodiments of the present disclosure, and those skilled in the art can also derive other drawings based on these drawings. Furthermore, the drawings described below are schematic diagrams and are not intended to limit the actual dimensions of the products, actual processes of the methods, actual timing of signals, and the like involved in the embodiments of the present disclosure.

[0009] FIG1 is a partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure;

[0010] FIG2 is a partial structural diagram of a host computer provided according to some embodiments of the present disclosure;

[0011] FIG3 is a structural diagram of an optical module provided according to some embodiments of the present disclosure;

[0012] FIG4 is an exploded view of an optical module according to some embodiments of the present disclosure;

[0013] FIG5 is a first structural diagram of an optical modulation chip provided according to some embodiments of the present disclosure;

[0014] FIG6 is a second structural diagram of an optical modulation chip provided according to some embodiments of the present disclosure;

[0015] FIG7 is a light path diagram of an optical modulation chip provided according to some embodiments of the present disclosure;

[0016] FIG8 is a schematic diagram illustrating the working principle of an optical modulation chip according to some embodiments of the present disclosure;

[0017] FIG9 is a structural diagram of an optical modulator provided according to some embodiments of the present disclosure;

[0018] FIG10 is a top view of an optical modulator according to some embodiments of the present disclosure;

[0019] FIG11 is a schematic diagram of electrical connections between an optical modulator and a modulation driver according to some embodiments of the present disclosure;

[0020] FIG12 is a schematic diagram of the relative position relationship between a first coupling waveguide and a second coupling waveguide according to some embodiments of the present disclosure;

[0021] FIG13 is a schematic structural diagram of a first coupling waveguide provided according to some embodiments of the present disclosure;

[0022] FIG14 is a schematic structural diagram of a second coupling waveguide provided according to some embodiments of the present disclosure;

[0023] FIG15 is a schematic diagram illustrating the relative positional relationship among a first coupling waveguide, a second coupling waveguide, and a third coupling waveguide according to some embodiments of the present disclosure;

[0024] FIG16 is a schematic structural diagram of a third coupled waveguide provided according to some embodiments of the present disclosure;

[0025] FIG17 is a schematic structural diagram of a first optical chip provided according to some embodiments of the present disclosure;

[0026] FIG18 is a schematic structural diagram of a second optical chip provided according to some embodiments of the present disclosure;

[0027] FIG19 is a schematic diagram of a preparation process of a first optical chip according to some embodiments of the present disclosure;

[0028] FIG20 is a schematic diagram of a preparation process of a second optical chip according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0029] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some embodiments of the present disclosure, not all embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present disclosure.

[0030] Unless the context requires otherwise, throughout the specification and claims, the term "comprise" and its other forms, such as the third person singular form "comprises" and the present participle form "comprising", are to be interpreted as open and inclusive, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are intended to indicate that a particular feature, structure, material or characteristic associated with the embodiment or example is included in at least one embodiment or example of the present disclosure. The schematic representation of the above terms does not necessarily refer to the same embodiment or example. In addition, the particular features, structures, materials or characteristics may be included in any one or more embodiments or examples in any appropriate manner.

[0031] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

[0032] When describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. For example, when describing some embodiments, the term "connected" may be used to indicate that two or more components are in direct physical or electrical contact with each other. For another example, when describing some embodiments, the term "coupled" may be used to indicate that two or more components are in direct physical or electrical contact. However, the term "coupled" or "communicatively coupled" may also refer to two or more components that are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents of this document.

[0033] “At least one of A, B and C” has the same meaning as “at least one of A, B or C” and both include the following combinations of A, B and C: A only, B only, C only, the combination of A and B, the combination of A and C, the combination of B and C, and the combination of A, B and C.

[0034] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0035] The use of "adapted to" or "configured to" herein is intended to be open and inclusive language that does not exclude devices adapted to or configured to perform additional tasks or steps.

[0036] As used herein, "about," "substantially," or "approximately" includes the stated value and an average value that is within an acceptable range of deviation from the particular value as determined by one of ordinary skill in the art taking into account the measurements in question and the errors associated with the measurement of the particular quantity (i.e., the limitations of the measurement system).

[0037] In optical communication technology, to establish information transmission between information processing devices, it is necessary to load the information onto light and use the propagation of light to achieve information transmission. Here, the light loaded with information is an optical signal. When transmitting optical signals in information transmission equipment, they can reduce the loss of optical power, thereby achieving high-speed, long-distance, and low-cost information transmission. The signals that information processing equipment can recognize and process are electrical signals. Information processing equipment typically includes optical network terminals (ONUs), gateways, routers, switches, mobile phones, computers, servers, tablets, televisions, etc., and information transmission equipment typically includes optical fibers and third-party coupling waveguides.

[0038] Optical modules can convert optical signals into electrical signals between information processing devices and information transmission devices. For example, at least one of the optical signal input or output ends of an optical module is connected to an optical fiber, and at least one of the electrical signal input or output ends of the optical module is connected to an optical network terminal. A first optical signal from the optical fiber is transmitted to the optical module, which converts the first optical signal into a first electrical signal and transmits the first electrical signal to the optical network terminal. A second electrical signal from the optical network terminal is transmitted to the optical module, which converts the second electrical signal into a second optical signal and transmits the second optical signal to the optical fiber. Because multiple information processing devices can transmit information via electrical signals, at least one of the multiple information processing devices needs to be directly connected to the optical module, rather than all of them. Here, the information processing device directly connected to the optical module is referred to as the optical module's host computer. Furthermore, the optical signal input or output end of the optical module can be referred to as an optical port, and the electrical signal input or output end of the optical module can be referred to as an electrical port.

[0039] Figure 1 is a partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure. As shown in Figure 1, 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.

[0040] One end of optical fiber 101 extends toward remote information processing device 1000, and the other end of optical fiber 101 is connected to optical module 200 through the optical port of optical module 200. Optical signals can be totally reflected in optical fiber 101, and the propagation of the optical signal in the direction of total reflection can almost maintain the original optical power. The optical signal undergoes multiple total reflections in optical fiber 101 to transmit the optical signal from remote information processing device 1000 to optical module 200, and vice versa, thereby achieving long-distance, low-power information transmission.

[0041] The optical communication system may include one or more optical fibers 101, and the optical fibers 101 may be 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 operating status of the optical module 200.

[0042] 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 to establish a unidirectional or bidirectional electrical signal connection between the host computer 100 and the optical module 200.

[0043] The host computer 100 also includes an external electrical interface that can access an electrical signal network. For example, the external electrical interface includes a Universal Serial Bus (USB) interface or a network cable interface 104. The network cable interface 104 is configured to access a 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 that an electrical signal connection is established between the local information processing device 2000 and the host computer 100 via the network cable 103. For example, a third electrical signal emitted by the local information processing device 2000 is transmitted to the host computer 100 via the network cable 103. The host computer 100 generates a second electrical signal based on the third electrical signal. The second electrical signal from the host computer 100 is transmitted to the optical module 200. 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. The second optical signal is then transmitted to the remote information processing device 1000 via the optical fiber 101. For example, a first optical signal from the remote information processing device 1000 is transmitted through the optical fiber 101. The first optical signal from the optical fiber 101 is transmitted to the optical module 200. The optical module 200 converts the first optical signal into a first electrical signal. The optical module 200 transmits the first electrical signal to the host computer 100. The host computer 100 generates a fourth electrical signal based on the first electrical signal and transmits the fourth electrical signal to the local information processing device 2000. It should be noted that optical modules are tools for converting optical signals into electrical signals. During this conversion process, the information does not change, but the encoding and decoding methods of the information can change.

[0044] 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.

[0045] FIG2 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, FIG2 only shows the structure of the host computer 100 related to the optical module 200. As shown in FIG2, the host computer 100 also 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 connect to the electrical port of the optical module 200; the heat sink 107 has a protruding structure such as fins that increase the heat dissipation area.

[0046] The optical module 200 is inserted into the cage 106 of the host computer 100. The cage 106 secures the optical module 200. Heat generated by the optical module 200 is transferred to the cage 106 and then dissipated through the heat sink 107. After the optical module 200 is inserted into the cage 106, the electrical port of the optical module 200 connects with the electrical connector inside the cage 106, thereby establishing a bidirectional electrical signal connection between the optical module 200 and the host computer 100. Furthermore, the optical port of the optical module 200 connects to the optical fiber 101, thereby establishing a bidirectional optical signal connection between the optical module 200 and the optical fiber 101.

[0047] Figure 3 is a structural diagram of an optical module according to some embodiments of the present disclosure, and Figure 4 is an exploded view of an optical module according to some embodiments of the present disclosure. As shown in Figures 3 and 4, optical module 200 includes a housing, a circuit board 300 disposed within the housing, an optical modulation chip 900, and a light source 1100. In this case, optical module 200 is a coherent optical module.

[0048] The housing includes 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.

[0049] 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, which covers the two lower side plates 2022 of the lower shell 202 to form the above-mentioned shell.

[0050] In some embodiments, the lower shell 202 includes a base plate 2021 and two lower side plates 2022 located on both sides of the base plate 2021 and arranged perpendicularly to the base 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 arranged perpendicularly to the cover plate 2011. The two upper side plates are combined with the two lower side plates 2022 to achieve the upper shell 201 covering the lower shell 202.

[0051] The direction of the line connecting the two openings 204 and 205 can be aligned with or inconsistent with the length of the optical module 200. For example, opening 204 is located at the end of the optical module 200 (the left end in FIG3 ), and opening 205 is also located at the end of the optical module 200 (the right end in FIG3 ). Alternatively, opening 204 is located at the end of the optical module 200, while opening 205 is located on the side of the optical module 200. Opening 204 is an electrical port, through which the gold finger 301 of the circuit board 300 extends and is inserted into the electrical connector of the host computer 100. Opening 205 is an optical port, configured to receive an external optical fiber 101, thereby connecting the optical fiber 101 to the optical modulation chip 900 in the optical module 200.

[0052] The combined assembly of the upper housing 201 and the lower housing 202 facilitates installation of the circuit board 300, optical modulation chip 900, and light source 1100 within the housing. The upper housing 201 and the lower housing 202 provide encapsulation and protection for these components. Furthermore, during assembly of the circuit board 300, optical modulation chip 900, and light source 1100, positioning components, heat dissipation components, and electromagnetic shielding components are easily positioned, facilitating automated production.

[0053] In some embodiments, the upper shell 201 and the lower shell 202 are made of metal materials, which facilitates electromagnetic shielding and heat dissipation.

[0054] 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.

[0055] For example, the unlocking component 600 is located on the outside of the two lower side panels 2022 of the lower housing 202 and includes a snap-fit ​​component that mates with 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 secures 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 between the snap-fit ​​component and the host computer, thereby releasing the optical module 200 from the cage 106 and allowing the optical module 200 to be removed from the cage 106.

[0056] The circuit board 300 includes circuit traces, electronic components, and chips. The electronic components and chips are connected according to the circuit design through the circuit traces to achieve functions such as power supply, electrical signal transmission, and grounding. Electronic components may include, for example, capacitors, resistors, transistors, and metal-oxide-semiconductor field-effect transistors (MOSFETs). Chips may include, for example, microcontroller units (MCUs), laser driver chips, transimpedance amplifiers (TIAs), limiting amplifiers, clock and data recovery chips (CDRs), power management chips, and digital signal processing (DSP) chips.

[0057] 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.

[0058] The circuit board 300 also includes a gold finger 301 formed on its end surface, and 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 set only on the surface of one side of the circuit board 300 (for example, the upper surface shown in Figure 4), or it can be set on the upper and lower surfaces of the circuit board 300 to provide a larger number of pins, thereby adapting to occasions where a large number of pins are required. 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.

[0059] The optical modulation chip 900 does not have its own light source. The light source 1100 serves as an external light source for the optical modulation chip 900. The light source 1100 emits light (e.g., from the side), and the light emitted enters the optical modulation chip 900. For example, the light source 1100 can be a laser box that encapsulates a laser. The laser emits light to generate a laser beam to provide the optical modulation chip 900 with transmitted laser light.

[0060] Lasers, with their superior single-wavelength characteristics and wavelength tuning properties, have become the preferred light source for optical modules and even fiber optic transmission. Other types of light, such as LEDs, are generally not used in common optical communication systems. Even if such light sources are used in special optical communication systems, the characteristics of their light sources and chip components differ significantly from those of laser light sources. This results in significant technical differences between optical modules using lasers and those using other light sources. Those skilled in the art generally do not believe that these two types of optical modules can provide technical inspiration for each other. Of course, the disclosed embodiments do not preclude the possibility of using other types of light, such as LEDs, as the light source 1100.

[0061] The light emitted by light source 1100 does not carry data. This light is the light to be modulated, which enters the optical modulation chip 900. The optical modulation chip 900 modulates the light to be modulated and adds an electrical signal to the light to obtain light carrying data, thereby generating an optical transmission signal and transmitting the optical signal. Furthermore, external light can enter the optical modulation chip 900, which demodulates the external light and receives the optical signal.

[0062] In some embodiments, the optical modulation chip 900 may be a silicon photonic chip, which integrates a modulator that can modulate and demodulate optical signals. Because silicon photonic chips are easily etched, other functional components such as optical splitters, combiners, mixers, and photodetectors can be integrated within them, thereby achieving more functionality. However, the fundamental properties of silicon materials lead to drawbacks in optical modulators, such as low modulation efficiency, large capacitance, limited bandwidth, and high optical loss.

[0063] In some other embodiments, the optical modulator chip 900 can be a thin-film lithium niobate chip. Thin-film lithium niobate has characteristics such as linear electro-optical effect. An external electric field will cause its refractive index in the corresponding direction to change linearly, so that the light waves transmitted in the medium have controllable 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.

[0064] However, thin-film lithium niobate is relatively hard and difficult to etch, making it difficult to integrate multiple functional devices on its surface. At the same time, thin-film lithium niobate chips have low optical loss.

[0065] FIG5 is a structural diagram 1 of an optical modulation chip provided according to some embodiments of the present disclosure; FIG6 is a structural diagram 2 of an optical modulation chip provided according to some embodiments of the present disclosure. As shown in FIG5 and FIG6, 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.

[0066] Of course, in other examples, the first substrate 910 can also be a substrate formed by other materials having characteristics such as linear electro-optical effect. As long as the light waves transmitted in the first substrate 910 have controllable intensity, phase and other information, the embodiment of the present disclosure does not limit the material of the first substrate 910.

[0067] The optical modulation chip 900 also includes a second substrate 920, which is disposed opposite the first substrate 910. In some embodiments, the second substrate 920 is a silicon-based substrate. Exemplarily, the silicon-based substrate includes a first silicon layer, a silicon oxide layer, and a second silicon layer stacked in layers. Because silicon-based materials facilitate the integration of various functional devices, other functional devices, such as an optical demodulator 921, are formed on the surface of the second substrate 920. The optical demodulator 921 demodulates the optical signal. Exemplarily, the optical demodulator 921 is a photodetector that can demodulate the optical signal into an electrical signal, thereby achieving optical signal demodulation.

[0068] Of course, in other examples, the second substrate 920 can also be a substrate formed of other materials that are extremely easy to etch. As long as other functional devices, such as splitters, combiners, mixers, photodetectors, etc., can be quickly and efficiently integrated on the second substrate 920, the embodiments of the present disclosure do not limit the material of the second substrate 920.

[0069] In some embodiments, to enable optical signal transmission, an end coupler 922, a first coupling waveguide 923, and a first optical splitter are formed on the surface of the second substrate 920, and a second coupling waveguide 913 is formed on the surface of the first substrate 910. The end 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 enabling optical signal transmission between the surfaces of the second substrate 920 and the first substrate 910.

[0070] The non-data-carrying light output by the light source 1100, i.e., the light to be modulated, enters the surface of the second substrate 920 through the end coupler 922. The non-data-carrying light is decomposed by the first optical splitter on the surface of the second substrate 920 into local oscillation light and the transmitting light source. The local oscillation light is transmitted to the optical demodulator 921 for coherent demodulation of the optical signal. The transmitting light source is output along the first coupling waveguide 923 until it is coupled into the second coupling waveguide 913, and then enters the optical modulator 911 on the surface of the first substrate 910 for optical signal modulation.

[0071] In some embodiments, to reduce the size of the optical modulation chip 900 and facilitate chip miniaturization, the second substrate 920 includes a protrusion 924, a first overlapping portion 925 and a second overlapping portion 926, respectively located on either side of the protrusion 924; and the first substrate 910 includes a first groove 912, a second groove 915 and a third groove 914, respectively located on either side of the first groove 912. For example, the protrusion 924 protrudes relative to the surfaces of the first overlapping portion 925 and the second overlapping portion 926; and the first groove 912 is recessed relative to the second groove 915 and the third groove 914.

[0072] 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.

[0073] Exemplarily, the second groove 915 and the third groove 914 are both located on one side of the first groove 912. For example, the second groove 915 and the third groove 914 are located above the first groove 912. At least a portion (e.g., an end portion) of the second substrate 920 is embedded in the first groove 912. The optical demodulator 921 is disposed on the second substrate 920 and is enclosed by the first groove 912. For example, the optical demodulator 921 is disposed at the end portion of the second substrate 920, so that when the end portion of the second substrate 920 is embedded in the first groove 912, the optical demodulator 921 is enclosed by the first groove 912. That is, the first groove 912 is configured to embed the optical demodulator 921. The provision of the second groove 915 facilitates reducing 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 brought close to the first substrate 910, thereby reducing the height of the optical modulation chip 900 and further reducing the size of the optical modulation chip 900, which is conducive to chip miniaturization.

[0074] In some embodiments, because the optical demodulator 921 has a certain height, in the present disclosure, the optical demodulator 921 is disposed within the protrusion 924, which is embedded within 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. This places the second substrate 920 close to the first substrate 910, thereby reducing the height of the optical modulation chip 900 and, in turn, the size of the optical modulation chip 900, facilitating 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 optical loss and facilitating optical signal transmission.

[0075] Exemplarily, the second groove 915 is connected to the first overlap portion 925 by optically matching adhesive, and the third groove 914 is connected to the second overlap portion 926 by optically matching adhesive. The inner wall surface of the first groove 912 is also filled with optically matching adhesive to achieve connection with the protrusion 924.

[0076] In some embodiments, an end coupler 922 is disposed on one side of the optical demodulator 921 and above the second overlapping portion 926. A first coupling waveguide 923 is disposed on the other side of the optical demodulator 921 and 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 optical signal transmission.

[0077] 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. Simultaneously, optical signal transmission is achieved via a first coupling waveguide 923 and a second coupling waveguide 913, thereby obtaining a hybrid integrated optical modulation chip. The optical modulation chip 900 of the present disclosure integrates two substrates, thereby enabling the integration of multiple functional devices via a silicon-based substrate and providing higher modulation efficiency via a thin-film lithium niobate-based substrate. This fully utilizes the advantages of both substrates, optimizes the modulation performance of the optical modulation chip 900, and improves the coherence performance of the optical module.

[0078] In some embodiments, the end coupler 922 is a silicon nitride coupler. To achieve optical signal coupling and 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 on one side of the silicon nitride optical waveguide 927 (e.g., above the silicon nitride optical waveguide 927 in FIG6 ). Light enters the end coupler 922 and is sequentially coupled and transmitted through the silicon nitride optical waveguide 927, the silicon waveguide 927a, and the optical waveguide 921a of the optical demodulator 921 before being coupled into the first coupling waveguide 923. This achieves optical signal transmission between the end coupler 922 and the first coupling waveguide 923, and transmits the light to be modulated from the end coupler 922 to the first coupling waveguide 923.

[0079] For example, the optical waveguide 921a of the optical demodulator 921 may also be a silicon waveguide. The silicon waveguide 927a, the optical waveguide 921a of the optical demodulator 921, and the first coupling waveguide 923 may be located on the same horizontal plane to reduce the transmission path length of the optical signal from the silicon waveguide 927a to the first coupling waveguide 923, reduce the refractive index and loss of the optical signal, and ensure that the optical signal can sequentially enter the first coupling waveguide 923 from the silicon waveguide 927a and the optical waveguide 921a of the optical demodulator 921. Of course, in some examples, the height difference between two adjacent devices among the silicon waveguide 927a, the optical waveguide 921a of the optical demodulator 921, and the first coupling waveguide 923 may be within the allowable range of low optical transmission loss.

[0080] In some embodiments, a grating is etched on the surface of the second coupling waveguide 913 to achieve a certain ratio of light splitting for optical power detection. When the second coupling waveguide 913 is a thin-film lithium niobate waveguide, the relatively high hardness of the thin-film lithium niobate waveguide makes it difficult to etch a grating on the surface of the second coupling waveguide 913. Therefore, a third coupling waveguide 916 is formed on one side of the second coupling waveguide 913 (e.g., above the second coupling waveguide 913 in FIG. 5 ). A grating is etched on the surface of the third coupling waveguide 916 to achieve a certain ratio of light splitting for optical power detection.

[0081] Exemplarily, the third coupling waveguide 916 is an amorphous silicon optical waveguide to facilitate etching to form a grating. 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 non-data-carrying light 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 non-data-carrying light into the second coupling waveguide 913. In some examples, the third coupling waveguide 916 can also be formed of other materials that are easily etchable, which is not limited here.

[0082] In the above example, the third coupling waveguide 916 is formed on the first substrate 910. In some examples, the third coupling waveguide 916 may also be provided on the second substrate 920 and may be located between the first coupling waveguide 923 and the second coupling waveguide 913. In this way, the third coupling waveguide 916 and the second substrate 920 may be made of the same material, namely silicon, thereby facilitating the fabrication of the third coupling waveguide 916.

[0083] 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 modulator arms of the optical modulator 911. Its refractive index changes accordingly, and the phase changes, thereby adjusting the phase difference between the two modulator arms of the optical modulator 911 and, in turn, adjusting the operating point of the modulator.

[0084] For example, the phase modulator 918b may be located on a side of the optical modulator 911 away from the second coupling waveguide 913 to alleviate or prevent the phase modulator 918b from transferring part of the heat to the second coupling waveguide 913 or to another modulation wall of the optical modulator 911, thereby affecting the adjustment of the phase difference.

[0085] In some embodiments, to effectively heat the phase modulator 918b, the projected area of ​​the phase modulator 918b on the surface of the first substrate 910 is hollowed out to form a hollowed-out area 918c. This reduces the amount of heat dissipated from the surface of the first substrate 910, thereby accumulating more heat near the phase modulator 918b and effectively heating the phase modulator 918b. In some embodiments, a welding portion 910b is formed on the surface of the first groove 912 opposite the optical demodulator 921. The optical demodulator 921 and the welding portion 910b are welded together via solder joints, thereby securing the optical demodulator 921 to the surface of the first groove 912. Of course, in other examples, the optical demodulator 921 and the surface of the first groove 912 can also be connected via conductive adhesive.

[0086] Figure 7 is an optical path diagram of an optical modulation chip provided according to some embodiments of the present disclosure. As shown in Figure 7, the transmission optical path diagram of the light to be modulated is shown. Light enters end coupler 922, is transmitted through silicon nitride optical waveguide 927 to silicon waveguide 927a and optical demodulator 921. After being split, a portion remains in optical demodulator 921 for coherent demodulation, while the remaining portion is transmitted through optical waveguide 921a of optical demodulator 921 and coupled into first coupling waveguide 923, thereby achieving optical signal transmission between end coupler 922 and first coupling waveguide 923, and transmitting the light to be modulated from end coupler 922 to first coupling waveguide 923.

[0087] 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 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.

[0088] The modulated optical signal returns along the original optical path until it is output through the end coupler 922 .

[0089] FIG8 is a schematic diagram illustrating the operating principle of an optical modulation chip according to some embodiments of the present disclosure. As shown in FIG8 , in some embodiments of the present disclosure, a second coupling waveguide 913 is formed on the surface of a first substrate 910, and a first coupling waveguide 923 is formed on the surface of a second substrate 920. The coupling of light waves between the first coupling waveguide 923 and the second coupling waveguide 913 is evanescent wave coupling, where 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 principle of evanescent wave coupling, the second substrate 920 is mounted on the surface of the first substrate 910 using evanescent wave coupling mounting technology, thereby obtaining a hybrid integrated optical modulation chip 900.

[0090] In addition, the end face coupler 922 formed on the surface of the second substrate 920 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 configured to output a modulated optical signal; the first input optical port 9222 is configured to receive light that does not carry data and is output by the light source 1100, that is, the light to be modulated; and the second input optical port 9223 is configured to receive an optical signal transmitted by an external optical fiber ribbon, that is, the light to be demodulated.

[0091] In some embodiments, the surface of the second substrate 920 is further integrated with an optical demodulation unit, which includes multiple functional components. For example, the surface of the second substrate 920 is further integrated with a first optical splitter 9281, a second optical splitter 9282, a third optical splitter 9283, a first frequency mixer 9284, a second frequency mixer 9285, a first detector 9286, and a second detector 9287. The first detector 9286 is the optical demodulator 921, and the second detector 9287 is configured to monitor the optical power of the received optical signal. For example, the second optical splitter 9282 and the third optical splitter 9283 are polarization beam splitters.

[0092] The non-data-carrying light output by the light source 1100 enters the surface of the second substrate 920 through the first optical input port 9222. The non-data-carrying light is decomposed by the first optical splitter 9281 into local oscillator light and the transmitting light source. The local oscillator light remains within the first detector 9286 and is configured for coherent demodulation of the optical signal. The transmitting light source is transmitted along the first coupling waveguide 923 and coupled into the second coupling waveguide 913 at the light output end of the second substrate 920 until it is transmitted to the optical modulator 911 for optical signal modulation. Therefore, in the present disclosure, the local oscillator 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.

[0093] 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.

[0094] The first TE polarized light and the second TE polarized light are mixed and amplified in a first mixer 9284 to produce a first mixed light. For example, 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 a second mixer 9285 to produce a second mixed light. Both the first mixed light and the second mixed light are amplified optical signals. These signals are received through coherent detection and converted into corresponding electrical signals. Digital signal processing removes interference factors such as dispersion, noise, and nonlinearity to restore the telecommunications signal stream.

[0095] 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 emission signal. The light emission signal is output to the outside of the second substrate 920 through the output optical port 9221 and is transmitted to the outside of the optical module along the external optical fiber ribbon.

[0096] 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, and ensuring the quality of modulation and demodulation.

[0097] 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 not only integrate multiple functional devices internally to achieve multifunctionality, but also have higher modulation efficiency, optimize modulation performance, and improve signal modulation quality.

[0098] In the embodiment of the present disclosure, the light output by the light source 1100 that does not carry data enters the surface of the second substrate 920 through the end coupler 922. The light that does not carry data is decomposed by the third optical splitter 9283 into local oscillator light and the transmitting end light source. The local oscillator light remains inside the optical demodulator 921 and is configured for coherent demodulation of the optical signal. The transmitting end light source is output along the first coupling waveguide 923, coupled into the second coupling waveguide 913 through the third coupling waveguide 916, and then transmitted to the optical modulator 911, which modulates the optical signal. The modulated optical signal is output in sequence through the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, and the end coupler 922.

[0099] The end coupler 922 transmits the light to be modulated via 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. The second coupling waveguide 913 transmits the light to be modulated toward the optical modulator 911. The modulated optical signal is transmitted via 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. The first coupling waveguide 923 transmits the modulated optical signal toward the end coupler 922.

[0100] In some embodiments of the present disclosure, the optical modulator 911 modulates the light to be modulated according to the electrical signal. For example, 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 provided 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 so that it meets 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 transmission signal carrying information.

[0101] In some embodiments, the modulation driver 918 is electrically connected to the optical modulator 911 via a metal layer 918a. For example, the modulation driver 918 is soldered to the surface of the metal layer 918a by flip-chip bonding, 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 achieving electrical connection between the modulation driver 918 and the optical modulator 911.

[0102] In some embodiments of the present disclosure, the optical modulation chip 900 is provided on the surface of the circuit board 300. The optical demodulator 921 is a photodetector that 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 further formed on the surface of the first substrate 910 to amplify the demodulated electrical signal. The transimpedance amplifier 919 is provided on one side of the optical demodulator 921, and the transimpedance amplifier 919 is electrically connected to the optical demodulator 921.

[0103] Since the optical demodulator 921 is embedded in the first groove 912, the optical demodulator 921 is wrapped in the first groove 912 and cannot be led out to achieve electrical connection with the transimpedance amplifier 919. To this end, a first via 919a is formed along the end of the optical demodulator 921 toward the circuit board 300 through the first substrate 910. Exemplarily, a through hole is etched 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 the first via 919a. The first via 919a penetrates the surface of the first substrate 910, and the first via 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 919a.

[0104] A second via 919b is formed along the bottom surface of the transimpedance amplifier 919, extending 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 dielectric, thereby forming the second via 919b. The second via 919b penetrates the surface of the first substrate 910, and the second via 919b is filled with a metal dielectric to achieve an 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 via the second via 919b.

[0105] A first connection portion 919d is formed at the end of the first via 919a on the surface of the circuit board 300, and a second connection portion 919e is formed at the end of the second via 919b on the surface of the circuit board 300. The first connection portion 919d and the second connection portion 919e are electrically connected to each other, thereby achieving an electrical connection between the optical demodulator 921 and the transimpedance amplifier 919. In some embodiments, the first connection portion 919d and the second connection portion 919e are electrically connected via a trace 919c.

[0106] Exemplarily, the first connection portion 919d is a first pad, the second connection portion 919e is a second pad, and the first pad and the second pad are electrically connected via the trace 919c, thereby achieving electrical connection between the optical demodulator 921 and the transimpedance amplifier 919.

[0107] In some embodiments, the first via 919a and the second via 919b are formed by etching through holes and depositing metal within the through holes. To uniformly maintain the depth of the etched through holes and the thickness of the deposited metal in the two electrical channels for ease of processing, a fourth recess 917 is formed on the surface of the first substrate 910, and the TIA 919 is disposed on the surface of the fourth recess 917. For example, the transimpedance amplifier 919 is flip-chip soldered to the surface of the fourth recess 917, such as using BGA solder balls.

[0108] For example, 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, 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.

[0109] In addition, the material between the fourth groove 917 and the bottom surface of the first substrate 910 can be the same as the material between the first groove 912 and the bottom surface of the first substrate 910 , for example, both are silicon layers, which can also simplify the processing technology.

[0110] In the present disclosure, the modulation driver 918 and the transimpedance amplifier 919 are disposed on the surface of the first substrate 910, thereby integrating the modulation driver 918 and the transimpedance amplifier 919 within the optical modulation chip 900, thereby saving space on the circuit board 300. At the same time, the distance between the modulation driver 918 and the optical modulator 911, as well as the distance between the optical demodulator 921 and the transimpedance amplifier 919, can be shortened, thereby facilitating signal transmission.

[0111] Of course, in other embodiments of the present disclosure, a modulation driver 918 is provided on the surface of the circuit board 300, and a wire bonding connection is made 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 a through hole is etched through the surface of the first substrate 910 at the bottom of the first groove 912 toward the circuit board 300 to form an electrical channel, which electrically connects the optical demodulator 921 to the circuit board 300. At the same time, the electrical channel has a solder pad formed on the surface of the circuit board 300, and a wire bonding connection is made between the solder pad and the transimpedance amplifier 919, thereby achieving an electrical connection between the optical demodulator 921 and the transimpedance amplifier 919.

[0112] 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. During operation, 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 applied to the first S modulation electrode and the second S modulation electrode, respectively. 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.

[0113] FIG9 is a structural diagram of an optical modulator provided according to some embodiments of the present disclosure; FIG10 is a top view of an optical modulator provided according to some embodiments of the present disclosure. As shown in FIG9 and FIG10, in some embodiments of the present disclosure, the optical modulator 911 is a thin-film lithium niobate-based modulator. The optical modulator 911 includes a first ridge waveguide 9111, a second ridge waveguide 9112, and 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 first differential modulation electrode 9113 comprises a first metal layer M1 and a second metal layer M2 at both ends, electrically connected via a via (VIA). Similarly, the second differential modulation electrode comprises a first metal layer and a second metal layer at both ends, electrically connected via a via. The same applies to the third and fourth differential modulation electrodes.

[0114] Modulation driver 918 is a differential driver and includes a first differential output terminal and a second differential output terminal. These terminals output a differential signal S+ and a differential signal S-, respectively, with the amplitude between the two differential signals being Vs. The differential signal S- is transmitted to the second and third differential modulation electrodes, respectively, while the differential signal S+ is transmitted to the first and fourth differential modulation electrodes, respectively, thereby forming two pairs of differential traveling wave electrodes.

[0115] Figure 11 is a schematic diagram of the electrical connection between an optical modulator and a modulation driver according to some embodiments of the present disclosure. As shown in Figure 11, 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. 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. 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.

[0116] 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.

[0117] In this disclosure, optical modulator 911 is a thin-film lithium niobate-based modulator. When modulation driver 918 is a differential driver, the optical modulation amplitude (OMA) can be increased. With the same driver power, the OMA of the lithium niobate modulator can be increased to 4 Vs. A larger OMA can reduce the bit error rate at the receiving end of the system, thereby improving optical reception performance.

[0118] FIG12 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. As shown in FIG12 , in some embodiments of the present disclosure, the first coupling waveguide 923 and the second coupling waveguide 913 are both tapered waveguides. For example, 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, or to ensure that more light enters the silicon optical waveguide from the lithium niobate waveguide, the first coupling waveguide 923 and the second coupling waveguide 913 are both configured as gradient waveguides.

[0119] Exemplarily, both the first coupling waveguide 923 and the second coupling waveguide 913 are tapered waveguides including a tapered section, thereby changing the effective refractive index of their respective modes, thereby changing the light field distribution, such that more light is coupled from the first coupling waveguide 923 into the second coupling waveguide 913, or vice versa. Exemplarily, the width of the first coupling waveguide 923 gradually decreases from the light input end to the light output end, thereby gradually decreasing the effective refractive index of its mode. The width of the second coupling waveguide 913 gradually increases from the light input end to the light output end, thereby gradually increasing the effective refractive index of its mode. This allows more light to be coupled from the first coupling waveguide 923 into the second coupling waveguide 913, thereby increasing coupling efficiency.

[0120] It should be noted that the light input end or light output end of the first coupling waveguide 923 or the second coupling waveguide 913 are named based on the transmission direction of the optical signal from the first coupling waveguide 923 to the second coupling waveguide 913. Thus, after the optical signal is modulated, it enters the second coupling waveguide 913 through the light output end of the second coupling waveguide 913, is coupled to the light output end of the first coupling waveguide 923 through the light input end of the second coupling waveguide 913, then enters the interior of the first coupling waveguide 923, and is finally transmitted to the end coupler 922 through the light input end of the first coupling waveguide 923.

[0121] The following description will also be made by taking the transmission direction of the optical signal coupled from the first coupling waveguide 923 to the second coupling waveguide 913 as an example.

[0122] Figure 13 is a schematic diagram of the structure of a first coupling waveguide provided according to some embodiments of the present disclosure; Figure 14 is a schematic diagram of the structure of a second coupling waveguide provided according to some embodiments of the present disclosure. As shown in Figures 13 and 14, the widths of the first coupling waveguide 923 and the second coupling waveguide 913 vary in opposite directions. By varying the corresponding widths, the effective refractive index of the mode of the first coupling waveguide 923 is reduced while the effective refractive index of the mode of the second coupling waveguide 913 is increased, thereby changing the light field distribution, allowing more light to be coupled from the first coupling waveguide 923 to the second coupling waveguide 913, thereby increasing coupling efficiency.

[0123] 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, transitioning 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 light output 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.

[0124] The cross section of the second coupling waveguide 913 has a gradually changing width, which 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 increase the output optical power of the second coupling waveguide 913 .

[0125] It is understandable that the present disclosure does not limit the specific shapes of the first coupling waveguide 923 and the second coupling waveguide 913. 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.

[0126] For example, the shape of the second coupling waveguide 913 may also be similar to that of the first coupling waveguide 923. For example, the cross-section of the second coupling waveguide 913 may also be composed of a rectangular waveguide and a tapered waveguide. The tapered waveguide is a tapered section of the second coupling waveguide 913, transitioning from the tapered waveguide to the rectangular waveguide. The larger width of the rectangular waveguide can increase the coupling efficiency from the second coupling waveguide 913 to the optical modulator 911; the gradually decreasing width of the tapered waveguide can transfer the light field to the first coupling waveguide 923, so that more light emitted from the first coupling waveguide 923 is coupled into the second coupling waveguide 913, thereby increasing the light output power on the surface of the second substrate 920.

[0127] Figure 15 is a schematic diagram illustrating the relative positional relationship between a first coupling waveguide, a second coupling waveguide, and a third coupling waveguide according to some embodiments of the present disclosure, and Figure 16 is a schematic diagram illustrating the structure of a third coupling waveguide according to some embodiments of the present disclosure. As shown in Figures 15 and 16 , based on the foregoing, 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 ratio of light splitting, thereby detecting 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.

[0128] From a top-down perspective, the first coupling waveguide 923, the third coupling waveguide 916, and the second coupling waveguide 913 are arranged sequentially from top to bottom. Light not carrying data, output from the end coupler 922, is coupled to the surface of the second substrate 920, propagates along the first coupling waveguide 923, and is output from the surface of the second substrate 920. It is then coupled into the third coupling waveguide 916, propagates along the third coupling waveguide 916, and is coupled into the second coupling waveguide 913 before being transmitted to the optical modulator 911 for optical signal modulation. The modulated optical signal then travels sequentially along the second coupling waveguide 913, the third coupling waveguide 916, the first coupling waveguide 923, and the end coupler 922, outputting from the surface of the second substrate 920. It is then transmitted to the outside of the optical module via an external optical fiber ribbon, achieving optical signal emission.

[0129] Since the refractive index of the silicon optical waveguide is greater than that 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, to couple more light from the third coupling waveguide 916 to the first coupling waveguide 923, the third coupling waveguide 916 includes a first gradient region 9161 and a second gradient region 9162. The first gradient region 9161 faces the first coupling waveguide 923, and the second gradient region 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 non-data-carrying light 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.

[0130] When setting, a rectangular segment may be provided between the first gradient zone 9161 and the second gradient zone 9162 . Of course, in some examples, the light output end of the first gradient zone 9161 is directly connected to the light input end of the second gradient zone 9162 .

[0131] It is understandable 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.

[0132] 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 various devices on the surface of the first substrate 910 are integrated into the first optical chip 900a, and the second substrate 920 and the various devices on the surface of the second substrate 920 are integrated into the second optical chip 900b. By integrating the first optical chip 900a and the second optical chip 900b together, the optical modulation chip 900 is obtained. The optical modulation chip 900 in the present disclosure integrates two optical chips, thereby fully utilizing the advantages of the two optical chips.

[0133] Figure 17 is a schematic diagram of the structure of a first optical chip provided according to some embodiments of the present disclosure. As shown in Figure 17, 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, with a second groove 915 and a third groove 914 formed on either side of the first groove 912. The first substrate 910 is a thin-film lithium niobate-based substrate, and accordingly, the first optical chip 900a is a thin-film lithium niobate chip.

[0134] 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. The light to be modulated is sequentially transmitted through the third coupling waveguide 916 and the second coupling waveguide 913 to the optical modulator 911 for optical signal modulation. The modulated optical signal is sequentially transmitted through the second coupling waveguide 913 and the third coupling waveguide 916 before being output from the first optical chip 900a.

[0135] 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 modulator arms of the optical modulator 911 is changed, and its refractive index changes accordingly, thereby changing the phase. This adjusts the phase difference between the two modulator arms of the optical modulator 911, and thus adjusts the operating point of the modulator.

[0136] In some embodiments, in order to effectively heat the phase modulator 918b, the projected area of ​​the phase modulator 918b on the surface of the first substrate 910 is hollowed out to form a hollowed-out area 918c 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.

[0137] 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, increasing the amplitude of the electrical signal to meet the requirements of the optical modulator 911. The optical modulator 911 then applies the electrical signal to the light to be modulated, generating an optical transmission signal carrying information.

[0138] In some embodiments, the modulation driver 918 is electrically connected to the optical modulator 911 via a metal layer 918a. To shorten the length of the metal layer 918a and improve 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 achieving an electrical connection between the modulation driver 918 and the optical modulator 911.

[0139] In some embodiments, a transimpedance amplifier 919 is 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.

[0140] Because the optical demodulator 921 is embedded in the first groove 912, the optical demodulator 921 is enclosed in the first groove 912 and cannot be led out to achieve electrical connection with the transimpedance amplifier 919. Therefore, 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.

[0141] Exemplarily, the first via 919a penetrates the surface of the first substrate 910, and the first via 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 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, facing the surface of the circuit board 300, to form a second via 919b. Exemplarily, the second via 919b penetrates 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. 5 , during configuration, a first connection portion 919d may be formed at the end of the first via 919a on the surface of the circuit board 300, and a second connection portion 919e may be formed at the end of the second via 919b on the surface of the circuit board 300. The first connection portion 919d and the second connection portion 919e are electrically connected to each other, thereby realizing electrical connection between the optical demodulator 921 and the transimpedance amplifier 919. The configuration of the first connection portion 919d realizes rapid positioning of the first via 919a on the circuit board 300, and also improves the electrical connection stability of the first via 919a on the circuit board 300. Similarly, the configuration of the second connection portion 919e realizes rapid positioning of the second via 919b on the circuit board 300, and also improves the electrical connection stability of the second via 919b on the circuit board 300.

[0142] In some embodiments, the first connection portion 919d and the second connection portion 919e are electrically connected via a trace 919c. For example, the first connection portion 919d is a first solder pad, and the second connection portion 919e is a second solder pad. The first solder pad and the second solder pad are electrically connected via the trace 919c in the circuit board 300, thereby electrically connecting the optical demodulator 921 to the transimpedance amplifier 919. It is understood that the trace 919c in the circuit board 300 is pre-fabricated when the circuit board 300 is manufactured. That is, a plurality of mutually insulated metal traces are formed at intervals within the circuit board 300, and at least the ends of at least some of the metal traces extend to the surface of the circuit board 300 to electrically connect to various devices on the surface of the circuit board 300, such as the solder pads of the present disclosure.

[0143] Of course, in some examples, the first via 919a can be directly soldered to the circuit board 300, and the end of the second via 919b can be directly soldered to the circuit board 300, so that the first via 919a and the second via 919b are electrically connected through the circuit board 300.

[0144] In some embodiments, the first via 919a and the second via 919b are formed by etching a through hole and depositing metal within the through hole. To uniformly maintain the depth of the etched through hole and the thickness of the deposited metal in the two electrical channels and facilitate processing, a fourth recess 917 is formed on the surface of the first substrate 910, and the TIA 919 is disposed on the surface of the fourth recess 917.

[0145] For example, 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-holes and the thickness of the deposited metal in the two electrical channels can be ensured to be the same, thereby simplifying the processing technology. Figure 18 is a schematic structural diagram of a second optical chip provided according to some embodiments of the present disclosure. As shown in Figure 18, 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 photonic chip.

[0146] The second substrate 920 includes a protruding portion 924, and a first overlapping portion 925 and a second overlapping portion 926 located on either side 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. This allows the second substrate 920 to be closer to the first substrate 910, thereby reducing the height of the optical modulation chip 900 and, in turn, the size of the optical modulation chip 900, facilitating chip miniaturization.

[0147] In some embodiments, an optical demodulator 921 is disposed within the protrusion 924. The optical demodulator 921 is embedded within the first groove 912. A welding portion 910b is formed on the surface of the first groove 912 opposite the optical demodulator 921. The end of the optical demodulator 921 is welded to the welding portion 910b via a welding point, thereby fixing the optical demodulator 921 to the surface of the first groove 912.

[0148] In some embodiments, to achieve optical signal transmission, an end coupler 922 and a first coupling waveguide 923 are formed on the surface of the second substrate 920. 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 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 optical signal transmission between the surfaces of the second substrate 920 and the first substrate 910.

[0149] Exemplarily, the end coupler 922 is a silicon nitride coupler. To achieve optical signal coupling and 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 sequentially coupled and transmitted through the silicon nitride optical waveguide 927, the silicon waveguide 927a, and the optical waveguide 921a of the optical demodulator 921 before being coupled into the first coupling waveguide 923. This achieves optical signal transmission between the end coupler 922 and the first coupling waveguide 923, and transmits the light to be modulated from the end coupler 922 to the first coupling waveguide 923.

[0150] 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 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. This places the second optical chip 900b close to the first optical chip 900a, thereby reducing the height and, consequently, the size of the optical modulation chip 900, facilitating 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 optical loss and facilitating optical signal transmission.

[0151] In the embodiment of the present disclosure, light to be modulated enters the interior of the second optical chip 900b through the corresponding optical port of the end coupler 922. It is then transmitted sequentially through the silicon nitride optical waveguide 927, silicon waveguide 927a, optical waveguide 921a of the optical demodulator 921, first coupling waveguide 923, third coupling waveguide 916, and second coupling waveguide 913 into the interior of the first optical chip 900a, where it reaches the optical modulator 911 for optical signal modulation. The modulated optical signal then passes sequentially through the second coupling waveguide 913, third coupling waveguide 916, first coupling waveguide 923, silicon nitride optical waveguide 927, and is then output from the first optical chip 900a through the end coupler 922.

[0152] In the embodiment of the present disclosure, for details regarding the specific implementation process of the hybrid integration of the first optical chip 900a and the second optical chip 900b, reference may be made to the specific implementation process of the optical modulation chip 900 shown in the embodiment of FIG. 5 .

[0153] In some embodiments of the present disclosure, the preparation process of the optical modulation chip 900 includes:

[0154] A 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. A first groove 912 is then formed by etching along the bottom surface of the second groove 915. The optical modulator 911 is formed by growing along the ridge waveguide of the optical modulator.

[0155] A first coupling waveguide 923 and a partial structure of the optical demodulator are formed by etching along the surface of the second substrate 920. A second etch stop layer is formed above the first coupling waveguide 923. Simultaneously, the optical demodulator 921 is grown along the partial structure of the optical demodulator to form the optical demodulator 921. Etching is then continued along the top surface of the second substrate 920 to the second etch stop layer to form a protrusion 924, a first overlapping portion 925, and a second overlapping portion 926.

[0156] 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 light modulation chip 900 .

[0157] 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 etched along the surface of the first substrate 910. When the optical modulator is grown along the ridge waveguide of the optical modulator, a hollowed-out region 918c is formed on the first substrate in the region corresponding to the phase modulator 918b.

[0158] 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 927 a , and an end coupler 922 are respectively formed on one side of the optical demodulator.

[0159] 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 .

[0160] 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 realizing electrical connection between the modulation driver 918 and the optical modulator 911.

[0161] 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 .

[0162] In some embodiments of the present disclosure, the fabrication process of the optical modulation chip 900 may include separately fabricating a first optical chip 900a and a second optical chip 900b, and then integrating the two together. In some embodiments, the optical modulation chip 900 is fabricated using evanescent wave coupling passive mounting technology. Due to the use of evanescent wave coupling passive mounting technology, the fabrication of the first optical chip 900a and the second optical chip 900b can be performed simultaneously.

[0163] FIG19 is a schematic diagram of a manufacturing process of a first optical chip according to some embodiments of the present disclosure. As shown in FIG19 , in some embodiments of the present disclosure, the first optical chip 900a is a thin-film lithium niobate chip.

[0164] In some embodiments, the preparation process of the first optical chip 900a includes the following steps:

[0165] S110: preparing a first substrate.

[0166] Exemplarily, first substrate 910 is a thin-film lithium niobate-based substrate, comprising, from bottom to top, a silicon layer, a silicon oxide layer, and a thin-film lithium niobate layer. The silicon oxide layer serves as an intermediate buried insulating layer, which provides full dielectric isolation between first substrate 910 and the device, thereby optimizing device performance.

[0167] S120: growing a thin-film lithium niobate layer along the surface of the first substrate to form a phase modulator, a ridge waveguide of the optical modulator, and a second coupled waveguide.

[0168] 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.

[0169] 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.

[0170] 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.

[0171] S140: growing and forming a third coupling waveguide and an etch stop layer along the current surface.

[0172] In some embodiments, a layer of amorphous silicon is deposited on the surface, and a single electron beam exposure process is used to form the third coupling waveguide 916. For example, the third coupling waveguide 916 is located obliquely above the second coupling waveguide 913. A certain thickness of silicon oxide is then deposited, and a first etch stop layer 901 is deposited thereon. The first etch stop layer 901 is located above the third coupling waveguide 916.

[0173] S150: Etching along the current surface to form a second groove, a third groove, a first groove and a fourth groove respectively.

[0174] 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. 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.

[0175] Exemplarily, the second groove 915 and the third groove 914 are respectively provided on both sides of the first groove 912. The first groove 912 is configured 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.

[0176] For example, the provision of first groove 912, second groove 915, and third groove 914 facilitates positioning of second optical chip 900b close to first optical chip 900a, thereby reducing the size of optical modulation chip 900 and facilitating chip miniaturization. Furthermore, the provision of second groove 915 shortens the coupling distance between third coupling waveguide 916 and the corresponding coupling waveguide in the second optical chip, facilitating optical signal transmission.

[0177] 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 in a flip-chip manner.

[0178] In some embodiments, a via 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.

[0179] S160: Prepare a second metal layer of the optical modulator, and then lay a metal layer electrically connecting the optical modulator and the modulation driver; and simultaneously prepare a first via hole and a second via hole.

[0180] In some embodiments, vias VIA and a second metal layer M2 are grown along the first metal layer M1 to form the optical modulator 911. Simultaneously, metal layer 918a is formed along the second metal layer M2 toward the right. Metal layer 918a electrically connects the optical modulator 911 to the modulation driver 918. The modulation driver 918 is soldered to the surface of the metal layer 918a via a flip-chip process.

[0181] 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.

[0182] After the above steps, the first optical chip 900a can be prepared.

[0183] Figure 20 is a schematic diagram of a manufacturing process of a second optical chip according to some embodiments of the present disclosure. As shown in Figure 20, in some embodiments of the present disclosure, the second optical chip 900b is a silicon photonic chip.

[0184] In some embodiments, the preparation process of the second optical chip 900b includes the following steps:

[0185] S210: preparing a second substrate.

[0186] 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.

[0187] 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.

[0188] S220: Growing a first coupled waveguide and various functional devices along the surface of the second silicon layer of the second substrate.

[0189] 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 simultaneously etched to form the various functional devices, including the above-mentioned first optical splitter 9281, second optical splitter 9282, third optical splitter 9283, first mixer 9284, second mixer 9285 and other devices.

[0190] 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.

[0191] S230: Continue to deposit silicon oxide along the surface of the silicon oxide layer of the second substrate, and manufacture end face couplers and silicon nitride optical waveguides.

[0192] 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. This silicon nitride surface is etched to form the end coupler 922, silicon nitride optical waveguide 927, and silicon waveguide 927a, respectively. A certain thickness of silicon oxide is then deposited on the surface. For example, the end coupler 922 is a silicon nitride end coupler.

[0193] S240: depositing and forming an etch stop layer along the current surface, and manufacturing a first metal electrode layer of each photodetector.

[0194] 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.

[0195] S250: Fabricate a second metal electrode layer of each photodetector.

[0196] 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 .

[0197] S260: etching to form a third recessed portion and a fourth recessed portion.

[0198] In some embodiments, etching is performed from the surface until the second etch stop layer 902 is reached, thereby forming a first overlapping portion 925 and a second overlapping portion 926 on both sides. The second etch stop layer 902 is then removed. The protrusion 924 is formed simultaneously with the formation of the first overlapping portion 925 and the second overlapping portion 926.

[0199] In some embodiments, an end portion 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 .

[0200] After the above steps, the second optical chip 900b can be prepared.

[0201] In the embodiment of the present disclosure, based on the first optical chip 900a and the second optical chip 900b prepared 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. This places the second optical chip 900b close to the first optical chip 900a, thereby reducing the height of the optical modulation chip 900 and, in turn, the size of the optical modulation chip 900, facilitating 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 optical loss and facilitating optical signal transmission.

[0202] In the embodiment of the present disclosure, light to be modulated enters the interior of the second optical chip 900b from the corresponding optical port of the end coupler 922, and is then transmitted sequentially 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 to the interior of the first optical chip 900a, where it reaches the optical modulator 911 for optical signal modulation. The modulated optical signal then passes sequentially 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, before being output from the first optical chip 900a via the end coupler 922.

[0203] 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, with a second groove and a third groove formed on both sides of the first groove respectively. An optical modulator is provided on the surface of the first substrate and is configured to modulate an optical signal. A second coupling waveguide is formed on one side of the optical modulator, the second coupling waveguide is arranged below the second groove, and the second coupling waveguide is configured to receive the light to be modulated and transmit the light to be modulated to the optical modulator for modulating the optical signal. The second substrate includes a protrusion, a first overlapping portion and a second overlapping portion respectively located on both sides of the protrusion, the protrusion 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, the optical demodulator is arranged in the protrusion, and is configured to demodulate the optical signal. An end face coupler is formed on one side of the optical demodulator, the end face coupler is arranged above the second overlapping portion, and the end face coupler is configured 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 located 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. This receives the light to be modulated output by the end coupler and transmits the modulated light 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 for optical signal modulation. The modulated optical signal is then output in sequence through the second coupling waveguide, the first coupling waveguide, and the end coupler.

[0204] 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 provided on the surfaces of the first substrate and the second substrate, thereby giving 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.

[0205] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that a person skilled in the art can conceive within the technical scope disclosed in the present disclosure should be included within the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. An optical module, comprising: Circuit boards; An optical modulation chip is electrically connected to the circuit board, and the optical modulation chip includes: A first substrate including a first groove; An optical modulator, disposed on a surface of the first substrate, configured to modulate the light to be modulated according to an electrical signal; A second coupling waveguide, disposed at one side of the optical modulator, configured to transmit the light to be modulated to the optical modulator; a modulation driver, disposed at the other side of the optical modulator, electrically connected to the optical modulator, and configured to process the electrical signal; A transimpedance amplifier is disposed on the surface of the first substrate; A second substrate is at least partially embedded in the first groove; an optical demodulator, disposed on the second substrate and wrapped by the first groove, and configured to demodulate an optical signal; the optical demodulator is disposed on one side of the transimpedance amplifier, and the optical demodulator is electrically connected to the transimpedance amplifier; A first coupling waveguide, provided at one side of the optical demodulator, optically connected to the second coupling waveguide, and configured to transmit the light to be modulated to the second coupling waveguide; Wherein, along the direction from the end of the optical demodulator toward the circuit board, a first via hole is formed through the first substrate to electrically connect the optical demodulator and the circuit board; A second via hole is formed through the first substrate along the bottom surface of the transimpedance amplifier toward the circuit board to electrically connect the transimpedance amplifier with the circuit board; The first via hole and the second via hole are electrically connected through a trace in the circuit board.

2. The optical module according to claim 1, wherein: 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.

3. The optical module according to claim 1, wherein: A second groove and a third groove are respectively formed on both sides of the first groove; The second substrate includes a protruding portion, a first overlapping portion and a second overlapping 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.

4. The optical module according to claim 1, wherein: A modulation driver is formed on the surface of the first substrate; The modulation driver is located at one side of the optical modulator; A metal layer is laid along the top of the optical modulator, one end of the metal layer is electrically connected to the optical modulator, and the other end of the metal layer is electrically connected to the modulation driver, thereby achieving electrical connection between the modulation driver and the optical modulator.

5. The optical module according to claim 1, wherein: A modulation driver is provided on one side of the optical modulator, and 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; The first differential output end of the modulation driver is electrically connected to the first differential modulation electrode and the fourth differential modulation electrode respectively, and the second differential output end is electrically connected to the second differential modulation electrode and the third differential modulation electrode respectively.

6. The optical module according to claim 1, wherein: The effective refractive index of the first coupling waveguide is greater than the effective refractive index of the second coupling waveguide; The width of the first coupling waveguide gradually decreases along the direction from the light input end to the light output end of the first coupling waveguide, so that the light to be modulated is coupled from the first coupling waveguide to the second coupling waveguide; The width of the second coupling waveguide gradually increases along the direction from the light input end to the light output end thereof so as to receive the light output from the first coupling waveguide.

7. The optical module according to claim 6, wherein: A third coupling waveguide is further formed on the surface of the first substrate, the third coupling waveguide is arranged between the first coupling waveguide and the second coupling waveguide, and one end of the third coupling waveguide is optically connected to the first coupling waveguide, and the other end of the third coupling waveguide is optically connected to the second coupling waveguide; The third coupling waveguide is formed with a grating for light splitting.

8. The optical module according to claim 7, wherein: The third coupling waveguide includes a first gradual change region and a second gradual change region, the first gradual change region faces the first coupling waveguide, and the second gradual change region faces the second coupling waveguide; The width of the first coupling waveguide gradually decreases along the direction from the light input end to the light output end thereof, and the width of the first gradient zone gradually increases along the direction from the light input end to the light output end of the first gradient zone, so that the light to be modulated is coupled from the first coupling waveguide to the first gradient zone; The width of the second gradient zone gradually decreases along the direction from the light input end to the light output end of the second gradient zone, and the width of the second coupling waveguide gradually increases along the direction from the light input end to the light output end, so that the light to be modulated is coupled from the second gradient zone to the second coupling waveguide.

9. The optical module according to claim 1, wherein: An end face coupler is formed on one side of the first coupling waveguide, and a silicon nitride optical waveguide is formed between the end face coupler and the first coupling waveguide; the end face coupler comprises: An optical output port, coupled to the optical modulator and configured to output a modulated optical signal; A first optical input port is coupled to the optical modulator and the optical demodulator respectively, and is configured to receive the light to be modulated; The second optical input port is coupled to the optical demodulator and is configured to receive an external optical signal.

10. The optical module according to claim 9, wherein: A silicon waveguide is formed on one side of the silicon nitride optical waveguide, and the silicon waveguide is configured to realize optical signal transmission between the silicon nitride optical waveguide and the optical waveguide of the optical demodulator; The silicon waveguide, the optical waveguide of the optical demodulator, and the first coupling waveguide are located on the same horizontal plane.

11. The optical module according to claim 1, wherein: A fourth groove is formed on one side of the optical demodulator; The transimpedance amplifier is disposed on the surface of the fourth groove.

12. The optical module according to claim 1, wherein: The second coupling waveguide is formed on one side of the optical modulator, and a phase modulator is formed on the other side; a hollow area is formed on the first substrate in an area opposite to the phase modulator.

13. The optical module according to claim 1, wherein: The modulation driver is formed on the surface of the first substrate; A metal layer is laid along the top of the optical modulator, one end of the metal layer is electrically connected to the optical modulator, and the other end of the metal layer is electrically connected to the modulation driver, thereby achieving electrical connection between the modulation driver and the optical modulator.

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