Optical module

Abstract

The invention provides an optical module which comprises a light source comprising a laser assembly, the laser assembly comprises a semiconductor gain chip and a wavelength tuning chip which form a resonant cavity, and the wavelength tuning chip comprises at least one micro-ring filter. The at least one micro-ring filter is used for screening out a light beam with a specific wavelength from light beams emitted by the semiconductor gain chip, the micro-ring filter comprises a first flat plate region, a second flat plate region and a contact electrode, the first flat plate region and the second flat plate region are located on the two sides of the silicon waveguide ridge region, an N-type doped region is arranged in the first flat plate region, and a P-type doped region is arranged in the second flat plate region; the P-type doped region and the N-type doped region form a PN junction electrically connected with the contact electrode, and electron hole pairs in the silicon waveguide ridge region, the first flat plate region and the second flat plate region can be absorbed by applying reverse bias voltage to the PN junction.

Description

optical modules

[0001] This application claims the priority of application number 202410630675.8 filed with the China Patent Office on May 21, 2024; the priority of application number 202410998365.1 filed with the China Patent Office on July 24, 2024; the priority of application number 202311082694.3 filed with the China Patent Office on August 25, 2023; and the priority of application number 202311043637.4 filed with the China Patent Office on August 18, 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] Optical communication technology is used in new services and application models such as cloud computing, mobile Internet, and video. In optical communication, optical modules are devices that realize the conversion of optical and electrical signals and are one of the key components in optical communication equipment.

[0004] Summary of the Invention

[0005] An embodiment of the present disclosure provides an optical module, including:

[0006] circuit boards;

[0007] A light source includes a laser assembly electrically connected to the circuit board, the laser assembly including a semiconductor gain chip and a wavelength tuning chip, the semiconductor gain chip being configured to emit a light beam within a wavelength range, the wavelength tuning chip and the semiconductor gain chip forming a resonant cavity; wherein the wavelength tuning chip includes:

[0008] an input coupler configured to receive the light beam emitted by the semiconductor gain chip and transmit the light beam of a specific wavelength to the semiconductor gain chip;

[0009] a power splitter connected to the input coupler, wherein the power splitter is configured to split the light beam input by the input coupler;

[0010] at least one micro-ring filter connected to an output end of the power divider, wherein the micro-ring filter is configured to filter out a light beam of a specific wavelength from the light beams in the wavelength range;

[0011] The microring filter includes a silicon waveguide ridge region, a first slab region, and a second slab region; the silicon waveguide ridge region is configured to transmit a light beam and generate electron-hole pairs when transmitting the light beam; the first slab region is located on one side of the silicon waveguide ridge region, and an N-type doped region is provided in the first slab region; the second slab region is located on the other side of the silicon waveguide ridge region, and a P-type doped region is provided in the second slab region, and the P-type doped region and the N-type doped region form a PN junction, and the PN junction is configured to absorb electron-hole pairs in the silicon waveguide ridge region, the first slab region, and the second slab region;

[0012] an optical chip electrically connected to the circuit board, wherein the optical chip is configured to receive an external optical signal;

[0013] an optical fiber configured to transmit the external optical signal;

[0014] a coupler assembly coupled to the optical fiber, the coupler assembly being configured to couple an external optical signal transmitted by the optical fiber to the optical chip; wherein the coupler assembly comprises:

[0015] a first coupling waveguide, one end of which is coupled to the optical fiber, and the first coupling waveguide is configured to receive an external optical signal transmitted by the optical fiber;

[0016] a second coupling waveguide configured to couple the external optical signal to the optical chip;

[0017] At least one transition waveguide is located between the first coupling waveguide and the second coupling waveguide, and the at least one transition waveguide is configured to couple the external optical signal transmitted by the first coupling waveguide to the second coupling waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0019] FIG1 is a partial structural diagram of an optical communication system provided according to some embodiments of the present disclosure;

[0020] FIG2 is a partial structural diagram of a host computer provided according to some embodiments of the present disclosure;

[0021] FIG3 is a structural diagram of an optical module provided according to some embodiments of the present disclosure;

[0022] FIG4 is an exploded view of an optical module according to some embodiments of the present disclosure;

[0023] FIG5 is a partial structural diagram of an optical module provided according to some embodiments of the present disclosure;

[0024] FIG6 is a structural diagram of a light source assembly in an optical module according to some embodiments of the present disclosure;

[0025] FIG7 is an exploded view of a light source assembly in an optical module according to some embodiments of the present disclosure;

[0026] FIG8 is a cross-sectional view of a light source assembly in a light module according to some embodiments of the present disclosure;

[0027] FIG9 is a schematic diagram of a wavelength tuning chip in an optical module according to some embodiments of the present disclosure;

[0028] FIG10 is a diagram illustrating the working principle of a wavelength tuning chip in an optical module according to some embodiments of the present disclosure;

[0029] FIG11 is a structural diagram of a microring filter in an optical module according to some embodiments of the present disclosure;

[0030] FIG12 is a cross-sectional view of a microring filter in an optical module according to some embodiments of the present disclosure;

[0031] FIG13 is a light path diagram of a light source assembly in an optical module according to some embodiments of the present disclosure;

[0032] FIG14 is a partial structural diagram of an optical module provided according to some embodiments of the present disclosure;

[0033] FIG15 is a first transverse cross-sectional view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0034] FIG16 is a top view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0035] FIG17 is a cross-sectional view taken along line AA in FIG16 ;

[0036] Figure 18 is a cross-sectional view taken along line BB in Figure 16;

[0037] FIG19 is a CC sectional view in FIG16;

[0038] FIG20 is a sectional view DD in FIG16;

[0039] FIG21 is a cross-sectional view EE in FIG16;

[0040] FIG22 is a second transverse cross-sectional view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0041] FIG23 is a third transverse cross-sectional view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0042] FIG24 is a fourth transverse cross-sectional view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0043] FIG25 is a longitudinal cross-sectional view of an end face coupler in an optical module according to some embodiments of the present disclosure;

[0044] FIG26 is a schematic diagram of the internal structure of an optical chip according to some embodiments of the present disclosure;

[0045] FIG27 is a first perspective structural diagram of an optical coupler according to some embodiments of the present disclosure;

[0046] FIG28 is a cross-sectional structural diagram 1 of an optical coupler provided according to some embodiments of the present disclosure;

[0047] FIG29 is a second perspective structural diagram of an optical coupler provided according to some embodiments of the present disclosure;

[0048] FIG30 is a second cross-sectional structural diagram of an optical coupler provided according to some embodiments of the present disclosure;

[0049] FIG31 is an assembly diagram between a transmission waveguide and a transition waveguide according to some embodiments of the present disclosure;

[0050] FIG32 is an assembly diagram of a transition waveguide and a coupled waveguide array according to some embodiments of the present disclosure;

[0051] FIG33 is a schematic structural diagram of an optical chip provided according to some embodiments of the present disclosure;

[0052] FIG34 is a first structural diagram of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0053] FIG35 is a cross-sectional view taken along line AA in FIG34 ;

[0054] FIG36 is a partial enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0055] FIG37 is a second partially enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0056] FIG38 is a third partially enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0057] FIG39 is a partial enlarged view of a polarization rotation beam splitter according to some embodiments of the present disclosure;

[0058] FIG40 is a second structural diagram of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0059] FIG41 is a cross-sectional view taken along line BB in FIG36 ;

[0060] FIG42 is a cross-sectional view taken along line CC in FIG36;

[0061] FIG43 is a schematic structural diagram of a mode conversion unit according to some embodiments of the present disclosure;

[0062] FIG44 is a cross-sectional view taken along line DD in FIG37 ;

[0063] FIG45 is a cross-sectional view taken along line EE in FIG37;

[0064] FIG46 is a cross-sectional view taken along line FF in FIG38 ;

[0065] FIG47 is a partial enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure;

[0066] FIG48 is a structural diagram of another mode coupling portion provided according to some embodiments of the present disclosure;

[0067] FIG49 is a structural diagram of another mode coupling portion provided according to some embodiments of the present disclosure;

[0068] Figure 50 is a cross-sectional view taken along the GG direction in Figure 39. DETAILED DESCRIPTION

[0069] The following will be combined with the accompanying drawings to clearly and in detail describe the technical solutions in some embodiments of the present disclosure. Obviously, the embodiments described are only some of the embodiments of the present disclosure, rather than all of the 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.

[0070] 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 within information transmission equipment, they can reduce optical power loss, thereby enabling 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 units (ONUs), gateways, routers, switches, mobile phones, computers, servers, tablets, televisions, etc., and information transmission equipment typically includes optical fibers and optical waveguides.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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, a light source 900, an optical chip, a transmitting fiber adapter 700, and a receiving fiber adapter 800, but the present disclosure is not limited thereto.

[0081] 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.

[0082] 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 perpendicular to the base plate 2021; the upper shell 201 includes a cover plate 2011, and the cover plate 2011 covers the two lower side plates 2022 of the lower shell 202 to form the above-mentioned shell.

[0083] 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.

[0084] The direction of the line connecting the two openings 204 and 205 can be consistent with the length of the optical module 200, or it can be inconsistent with the length of the optical module 200. For example, opening 204 is located at the end of the optical module 200 (the right end in Figure 3), and opening 205 is also located at the end of the optical module 200 (the left end in Figure 3). 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, from which the gold finger 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, so that the optical fiber 101 can connect to the optical transceiver component 900 in the optical module 200.

[0085] The combined assembly of upper and lower housings 201 and 202 facilitates installation of components such as the circuit board 300, light source 900, optical chip, transmitting fiber adapter 700, and receiving fiber adapter 800 within the housing. These components are encapsulated and protected by the upper and lower housings 201 and 202. Furthermore, when assembling components such as the circuit board 300, light source 900, optical chip, transmitting fiber adapter 700, and receiving fiber adapter 800, the combined assembly of upper and lower housings 201 and 202 facilitates the placement of positioning components, heat dissipation components, and electromagnetic shielding components for these components, facilitating automated production.

[0086] In some embodiments, the upper shell 201 and the lower shell 202 are made of metal materials, which facilitates electromagnetic shielding and heat dissipation.

[0087] In some embodiments, the optical module 200 further includes an unlocking component 600 located outside its housing. The unlocking component 600 is configured to achieve a fixed connection between the optical module 200 and the host computer 100, or to release the fixed connection between the optical module 200 and the host computer 100.

[0088] 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.

[0089] 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 (LAs), clock and data recovery chips (CDRs), power management chips, and digital signal processing (DSP) chips.

[0090] 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.

[0091] The circuit board 300 also includes a gold finger formed on the surface of its end, and the gold finger is composed of a plurality of independent pins. The circuit board 300 is inserted into the cage 106, and the gold finger is connected to the electrical connector in the cage 106. The gold finger 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 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.

[0092] In some embodiments, the light source 900 and the optical chip are physically separated from the circuit board 300 and then electrically connected to the circuit board 300 via a flexible circuit board or electrical connectors.

[0093] In some embodiments, the light source 900 and the optical chip can be directly disposed on the circuit board 300. For example, the light source 900 and the coherent optical chip can be disposed on the surface of the circuit board 300 or on the side of the circuit board 300.

[0094] In some embodiments, the optical chip may be a related optical chip, but is not particularly limited.

[0095] Figure 5 is a partial structural diagram of an optical module provided according to some embodiments of the present disclosure. As shown in Figure 5, a light source 900 is electrically connected to the circuit board 300 and is configured to emit a light beam of a specific wavelength. Light source 900 may include a semiconductor gain chip and a wavelength tuning chip. The semiconductor gain chip emits a light beam within a wavelength range. The wavelength tuning chip selects a light beam of a specific wavelength from the light beam within the wavelength range. The wavelength tuning chip and the semiconductor gain chip form a resonant cavity. The light beam of the specific wavelength is reflected back and forth between the wavelength tuning chip and the semiconductor gain chip, thereby achieving stable output of the light beam of the specific wavelength from the semiconductor gain chip.

[0096] The coherent optical chip 1100 is mounted on the circuit board 300. The coherent optical chip 1100 is used to achieve high-speed optical-to-electrical signal conversion. That is, the coherent optical chip includes an optical transmission interface, an optical reception interface, and a local oscillator optical interface. The optical transmission interface extends from a first optical fiber, the optical reception interface extends from a second optical fiber, and the local oscillator optical interface extends from a third optical fiber. The optical transmission interface is connected to the transmission optical fiber adapter 700 via the first optical fiber, the optical reception interface is connected to the reception optical fiber adapter 800 via the second optical fiber, and the local oscillator optical interface is connected to the light source 900 via the third optical fiber. The coherent optical chip 1100 is also connected to the DSP chip 302.

[0097] The narrow-linewidth, high-power laser emitted by the light source 900 is input into the coherent optical chip 1100 through the local oscillator optical interface. The laser is then split into beams within the coherent optical chip 1100. One beam, serving as the transmit beam, enters the coherent modulator within the coherent optical chip. Driven by the high-speed electrical signal of the DSP chip 302, the electro-optical signal is converted. The converted high-speed optical signal is then output from the optical transmit interface and transmitted via the first optical fiber to the transmit optical fiber adapter 700, thereby achieving coherent light emission.

[0098] The other beam serves as a local oscillator beam, which receives the high-speed optical signal transmitted by the optical fiber adapter 800 and is input into the coherent optical chip 1100 from the optical receiving interface. The local oscillator beam and the high-speed optical signal are coherently demodulated, and the demodulated electrical signal enters the DSP chip 302 for signal processing, thereby realizing the reception of coherent light.

[0099] In some embodiments, the narrow linewidth and high power laser emitted by the light source 900 is a laser of a specific wavelength.

[0100] The optical module provided by the embodiments of the present disclosure may include a circuit board, a light source, an optical chip, an optical fiber, and a coupler assembly.

[0101] In some embodiments, a light source includes a laser assembly electrically connected to a circuit board. The laser assembly includes a semiconductor gain chip and a wavelength tuning chip. The semiconductor gain chip is configured to emit a light beam within a wavelength range. The wavelength tuning chip and the semiconductor gain chip form a resonant cavity. The wavelength tuning chip includes: an input coupler configured to receive a light beam emitted by the semiconductor gain chip and transmit a light beam of a specific wavelength to the semiconductor gain chip; a power splitter connected to the input coupler and configured to split the light beam input by the input coupler; and at least one microring filter connected to an output end of the power splitter and configured to filter out a light beam of a specific wavelength from the light beams within the wavelength range.

[0102] The microring filter includes a silicon waveguide ridge region, a first flat plate region, and a second flat plate region; the silicon waveguide ridge region is configured to transmit a light beam and generate electron-hole pairs when transmitting the light beam; the first flat plate region is located on one side of the silicon waveguide ridge region, and an N-type doped region is provided in the first flat plate region; the second flat plate region is located on the other side of the silicon waveguide ridge region, and a P-type doped region is provided in the second flat plate region. The P-type doped region and the N-type doped region form a PN junction, and the PN junction is configured to absorb electron-hole pairs in the silicon waveguide ridge region, the first flat plate region, and the second flat plate region.

[0103] The structure of the laser assembly provided above can solve the nonlinear effect problem of the silicon optical resonator as a laser resonator under high optical power, thereby realizing a high optical power, narrow linewidth, and widely tunable laser. The specific structure of the laser assembly can be understood by referring to the following content.

[0104] In some embodiments, the optical chip is electrically connected to the circuit board, and the optical chip is configured to receive an external optical signal; the optical fiber is configured to transmit the external optical signal; the coupler assembly is coupled to the optical fiber, and the coupler assembly is configured to couple the external optical signal transmitted by the optical fiber to the optical chip; wherein the coupler assembly includes: a first coupling waveguide, one end of the first coupling waveguide is coupled to the optical fiber, and the first coupling waveguide is configured to receive the external optical signal transmitted by the optical fiber; a second coupling waveguide, and the second coupling waveguide is configured to couple the external optical signal to the optical chip; at least one transition waveguide is located between the first coupling waveguide and the second coupling waveguide, and the at least one transition waveguide is configured to couple the external optical signal transmitted by the first coupling waveguide to the second coupling waveguide.

[0105] The optical chip provided above, and the coupler assembly disposed between the optical chip and the optical fiber, can address the high coupling loss between the silicon-based optical waveguide and the single-mode optical fiber, thereby achieving ultra-low coupling insertion loss between the silicon-based optical waveguide and the single-mode optical fiber. The specific structure of the coupler assembly can be understood by referring to the following content.

[0106] Figure 6 is a structural diagram of a light source assembly in an optical module according to some embodiments of the present disclosure, and Figure 7 is an exploded view of a light source assembly in an optical module according to some embodiments of the present disclosure. As shown in Figures 6 and 7, light source 900 includes a laser assembly 901 and an internal fiber adapter 902. Laser assembly 901 is used to generate laser light of a specific wavelength. Internal fiber adapter 902 is connected to the local oscillator optical interface of coherent optical chip 1100 via a local oscillator optical fiber, so that the laser light generated by laser assembly 901 is input to coherent optical chip 1100 through internal fiber adapter 902 and the local oscillator optical fiber.

[0107] The laser assembly 901 includes a tube shell 9011, an electrical connector 9012 and a cover plate 9013. The tube shell 9011 includes a bottom plate, a first side plate, a second side plate, a third side plate and a fourth side plate. The first side plate, the second side plate, the third side plate and the fourth side plate are connected to the bottom plate. The first side plate and the second side plate are arranged opposite to each other, and the third side plate and the fourth side plate are arranged opposite to each other. In this way, the bottom plate, the first side plate, the second side plate, the third side plate and the fourth side plate constitute a shell with an open top.

[0108] The third side panel faces the transmitting fiber adapter 700, and the fourth side panel faces the coherent optical chip 1100. An open slot is formed on the third side panel, and a mounting slot is formed on the fourth side panel. The open slot and the mounting slot are connected to form an L-shaped slot. The electrical connector 9012 has an L-shaped structure and is inserted into the L-shaped slot of the housing 9011 to achieve a connection between the electrical connector 9012 and the housing 9011.

[0109] The electrical connector 9012 has multiple metal pins formed on the side surface outside the tube shell 9011, and the multiple metal pins are welded to the pin pads on the circuit board 300 to achieve electrical connection between the electrical connector 9012 and the circuit board 300; the electrical connector 9012 has solder pads formed on the side surface inside the tube shell 9011.

[0110] In some embodiments, a through hole is formed on the fourth side plate, and one end of the internal optical fiber adapter 902 is inserted into the through hole to achieve assembly of the internal optical fiber adapter 902 and the tube shell 9011.

[0111] A housing cavity 9014 is formed within the tube shell 9011, and an optical assembly 903 is installed within the housing cavity 9014. The optical assembly 903 is electrically connected to the solder pads on the electrical connector 9012, so that the optical assembly 903 generates a light beam of a specific wavelength. The light beam of the specific wavelength generated by the optical assembly 903 is transmitted to the local oscillator fiber via the internal optical fiber adapter 902, and then emitted into the coherent optical chip 1100 via the local oscillator fiber.

[0112] In some embodiments, the optical assembly 903 includes a wavelength tuning chip 9031, a semiconductor gain chip 9032, a first lens 9033, an isolator 9034, a second lens 9035, a semiconductor amplifier chip 9036, a third lens 9037, a beam splitter 9038, a power monitor 9039, and a fourth lens 9040. The semiconductor gain chip 9032 is located between the electrical connector 9012 and the internal fiber adapter 902. The semiconductor gain chip 9032 is used to emit a light beam within a wavelength range.

[0113] The wavelength tuning chip 9031 is located between the electrical connector 9012 and the semiconductor gain chip 9032. The wavelength tuning chip 9031 is electrically connected to pads on the electrical connector 9012 via bonding wires. The wavelength tuning chip 9031 is configured to receive light beams within a wavelength range and filter out a light beam of a specific wavelength from within the wavelength range. The wavelength tuning chip 9031 is also configured to inject the light beam of the specific wavelength into the semiconductor gain chip 9032. The wavelength tuning chip 9031 and the semiconductor gain chip 9032 form a resonant cavity. The light beam of the specific wavelength is reflected back and forth between the wavelength tuning chip 9031 and the semiconductor gain chip 9032, achieving stable output of the light beam of the specific wavelength from the semiconductor gain chip. In some embodiments, the wavelength tuning chip 9031 is a silicon photonics chip.

[0114] In some embodiments, the semiconductor gain chip 9032 is made of III-V gain materials and includes two optical waveguide end faces. One end face adopts a tilted waveguide structure and is coated with an anti-reflection film to achieve extremely low light field reflectivity. It is used to couple with the input coupler of the wavelength tuning chip 9031, facilitating the back-and-forth reflection of a specific wavelength light beam between the semiconductor gain chip 9032 and the wavelength tuning chip 9031. The other end face adopts a straight waveguide structure and is coated with a reflective film with a certain reflectivity to achieve light field reflection and transmission functions. When the specific wavelength light beam oscillates to a certain extent, the semiconductor gain chip 9032 emits a light beam of the specific wavelength.

[0115] The fourth lens 9040 is located between the wavelength tuning chip 9031 and the semiconductor gain chip 9032 . The fourth lens 9040 is used to collimate the light beam within a wavelength range output by the semiconductor gain chip 9032 so that the light beam output by the semiconductor gain chip 9032 is incident on the wavelength tuning chip 9031 .

[0116] The first lens 9033 is located between the semiconductor gain chip 9032 and the internal fiber adapter 902. The first lens 9033 is used to collimate the specific wavelength light beam output by the semiconductor gain chip 9032. In some embodiments, the first lens 9033 is a collimating lens.

[0117] The isolator 9034 is located between the first lens 9033 and the internal fiber adapter 902 . The isolator 9034 is used to prevent the light beam incident on the internal fiber adapter 902 from being reflected back into the semiconductor gain chip 9032 , thereby reducing the impact of light path reflection and further reducing the noise level of the light source 900 .

[0118] The second lens 9035 is located between the isolator 9034 and the internal fiber adapter 902. The second lens 9035 is used to converge the light beam of a specific wavelength passing through the isolator 9034 to the internal fiber adapter 902. In some embodiments, the second lens 9035 is a converging lens.

[0119] The semiconductor amplifier chip 9036 is located between the second lens 9035 and the internal optical fiber adapter 902. The second lens 9035 converges the specific wavelength light beam to the semiconductor amplifier chip 9036. The semiconductor amplifier chip 9036 is used to amplify the power of the specific wavelength light beam to increase the optical power of the specific wavelength light beam.

[0120] The third lens 9037 is located between the semiconductor amplifier chip 9036 and the internal fiber adapter 902. The third lens 9037 is used to collimate the amplified light beam of a specific wavelength. In some embodiments, the third lens 9037 is a collimating lens.

[0121] The beam splitter 9038 is located between the third lens 9037 and the internal optical fiber adapter 902 . The beam splitter 9038 is used to split the light beam of a specific wavelength into two paths, one path is coupled to the power monitor 9039 , and the other path is coupled to the internal optical fiber adapter 902 .

[0122] The power monitor 9039 is located between the beam splitter 9038 and the first side plate of the tube shell 9011. The power monitor 9039 is used to monitor the optical power of the specific wavelength light beam in real time. When the optical power of the specific wavelength light beam is less than the preset optical power range, the amplification factor of the semiconductor amplifier chip 9036 is increased so that the optical power of the specific wavelength light beam is within the preset optical power range; when the optical power of the specific wavelength light beam is greater than the preset optical power range, the amplification factor of the semiconductor amplifier chip 9036 is reduced so that the optical power of the specific wavelength light beam is within the preset optical power range.

[0123] Figure 8 is a cross-sectional view of a light source assembly in an optical module according to some embodiments of the present disclosure. As shown in Figure 8, in some embodiments, a semiconductor cooler 905 is further disposed within the accommodating cavity 9014. A substrate 904 is mounted on the cooling surface of the semiconductor cooler 905, and the optical assembly 903 is mounted on the substrate 904. The semiconductor cooler 905 can control the temperature of the wavelength tuning chip 9031 to adjust the wavelength of the light beam output by the wavelength tuning chip 9031, so that the wavelength tuning chip 9031 outputs a light beam of a specific wavelength.

[0124] An optical window 9021 and a fifth lens 9022 are provided in the internal optical fiber adapter 902. The optical window 9021 is located near the beam splitter 9038. Light emitted from the beam splitter 9038 enters the internal optical fiber adapter 902 through the optical window 9021. The light is then focused and coupled to the optical fiber ferrule in the internal optical fiber adapter 902 by the fifth lens 9022, thereby coupling the specific wavelength light beam emitted by the optical assembly 903 to the internal optical fiber adapter 902.

[0125] In some embodiments, to enable the optical assembly 903 to generate a light beam of a specific wavelength, the wavelength tuning chip 9031 integrates multiple microring filters, and utilizes the vernier effect of multiple different microring filters to achieve the wavelength tunability of the wavelength tuning chip 9031.

[0126] Figure 9 is a schematic diagram of a wavelength tuning chip in an optical module according to some embodiments of the present disclosure. As shown in Figure 9, an input coupler 906, a phase modulator 907, a power splitter 908, a first microring filter 909, and a second microring filter 910 are formed within the wavelength tuning chip 9031. The input coupler 906, the phase modulator 907, the power splitter 908, the first microring filter 909, and the second microring filter 910 are all formed by the wavelength tuning chip 9031 using a complementary metal oxide semiconductor (CMOS) process.

[0127] The input coupler 906 is disposed at one end face of the wavelength tuning chip 9031 . The input coupler 906 is used to receive a light beam of a wavelength range emitted by the semiconductor gain chip 9032 , and is also used to output a light beam of a specific wavelength screened by the wavelength tuning chip 9031 to the outside of the wavelength tuning chip 9031 .

[0128] The specific wavelength light beam is reflected back and forth between the wavelength tuning chip 9031 and the semiconductor gain chip 9032 , so that the semiconductor gain chip 9032 and the wavelength tuning chip 9031 form a resonant cavity, thereby achieving stable output of the specific wavelength light beam by the semiconductor gain chip 9032 .

[0129] In some embodiments, the input coupler 906 employs an inclined waveguide design, i.e., the optical waveguide of the input coupler 906 is arranged at a certain angle to the end face of the wavelength tuning chip 9031. Thus, when the light beam emitted by the semiconductor gain chip 9032 enters the input coupler 906 from the upper right, part of the light beam may be reflected at the end face of the wavelength tuning chip 9031. The reflected light beam is then emitted from the upper right instead of returning to the semiconductor gain chip 9032 along the original path. This reduces the impact of the light reflected from the end face of the wavelength tuning chip 9031 on the semiconductor gain chip 9032.

[0130] Since one end face of the semiconductor gain chip 9032 employs a tilted waveguide structure, the input coupler 906 is arranged parallel to the tilted waveguide structure of the semiconductor gain chip 9032 in the optical path direction, thereby matching the semiconductor gain chip 9032 with the wavelength tuning chip 9031, reducing reflection of the light field of the input coupler 906, and improving the quality of the light beam.

[0131] In some embodiments, the input coupler 906 and the tilted waveguide structure of the semiconductor gain chip 9032 may be arranged parallel to the optical path direction, so that the output angle of the specific wavelength light beam output by the input coupler 906 is 20°.

[0132] The phase modulator 907 is located between the input coupler 906 and the power divider 908. The phase modulator 907 is used to adjust the wavelength of the light beam supported by the resonant cavity so that the specific wavelength light beam filtered by the first microring filter 909 and the second microring filter 910 coincides with the light beam in the resonant cavity.

[0133] In some embodiments, a heater is provided on the phase modulator 907. By changing the heater, the cavity length of the phase modulator 907 is changed, and the cavity length of the resonant cavity is thereby changed, so that a light beam of a certain wavelength supported by the resonant cavity coincides with a light beam of a specific wavelength screened out by the two microring resonant cavities.

[0134] The power splitter 908 is located between the phase modulator and the first microring filter 909. The power splitter 908 is used to split the light beam output by the phase modulator 907 into two beams. The power splitter 908 is also used to combine light beams of specific wavelengths filtered by the first microring filter 909 and the second microring filter 910.

[0135] A power splitter generally refers to a power distributor. A power splitter is a device that divides one input signal energy into two or more outputs of equal or unequal energy. It can also combine the energy of multiple signals into one output, which is also called a combiner.

[0136] The power splitter 908 splits the light beam output by the phase modulator 907 into two light beams. One light beam first passes through the first microring filter 909 and then through the second microring filter 910, while the other light beam first passes through the second microring filter 910 and then through the first microring filter 909. The power splitter 908 can also combine the light beam of a specific wavelength that has first passed through the first microring filter 909 and then through the second microring filter 910 and then through the first microring filter 909 into a single light beam of a specific wavelength.

[0137] In some embodiments, the splitting ratio of the power splitter 908 can be 50%:50%, that is, the power splitter 908 splits one light beam into two light beams at a ratio of 50%:50%. The two light beams are filtered by the first microring filter 909 and the second microring filter 910 and then return to the power splitter 908. According to the principle of reversibility of the optical path, theoretically, other losses except for the losses passing through the first microring filter 909, the second microring filter 910 and the optical waveguide are zero.

[0138] The power splitter 908 can also have a splitting ratio of 20%:80%. The power splitter 908 splits one optical beam into two optical beams at a ratio of 20%:80%. The two optical beams are filtered by the first microring filter 909 and the second microring filter 910 before returning to the power splitter 908. According to the principle of optical path reversibility, theoretically, other losses other than the losses in the first microring filter 909, the second microring filter 910, and the optical waveguide are greater than zero.

[0139] In some embodiments, to minimize beam loss, the splitting ratio of the power splitter is 50%:50%.

[0140] The first microring filter 909 cooperates with the second microring filter 910 to filter out a light beam of a specific wavelength from a light beam within a wavelength range emitted by the semiconductor gain chip 9032. The first microring filter 909 is coupled to the power splitter 908 via a first straight optical waveguide, the first microring filter 909 is coupled to the second microring filter 910 via a second straight optical waveguide, and the second microring filter 910 is coupled to the power splitter 908 via a third straight optical waveguide.

[0141] Both the first microring filter 909 and the second microring filter 910 are microring structures, but they have different circumferences. This results in different wavelengths of the light beams filtered by the first microring filter 909 and the second microring filter 910. The two microring filters of different sizes have different mode wavelength intervals. The position of the mode wavelengths can be adjusted by changing the refractive index of the resonant cavity through the thermo-optical effect. Based on the vernier effect, a specific wavelength can be selected only when the mode wavelengths of the two microring filters coincide, causing the wavelength tuning chip 9031 to output a light beam of a specific wavelength, thus achieving wavelength tunability.

[0142] FIG10 is a diagram illustrating the working principle of a wavelength tuning chip in an optical module according to some embodiments of the present disclosure. As shown in FIG10 , in some embodiments, the principle of the first microring filter 909 and the second microring filter 910 screening a specific wavelength beam is as follows:

[0143] A light beam within a wavelength range is incident on the input end of the first straight optical waveguide (the end near the power divider 908). When the light beam reaches the first coupling region between the first straight optical waveguide and the first microring filter 909, a portion of the light beam is coupled into the first microring filter 909, and the remaining portion of the light beam is output from the output end of the first straight optical waveguide (the end away from the power divider 908). After entering the first microring filter 909 and propagating through the second coupling region formed by the second straight optical waveguide and the first microring filter 909, a portion of the light beam is coupled into the second straight optical waveguide, while the remaining portion of the light beam continues to propagate within the first microring filter 909. When the light beam propagating within the first microring filter 909 meets the resonance condition mλ = nl of the first microring filter 909, resonance occurs, resulting in coherence enhancement. The optical power of the light beam received by the second straight optical waveguide from the first microring filter 909 is also increased, while the light beam that does not meet the resonance condition is output from the output end of the first straight optical waveguide. Where λ is the wavelength of the light beam, l is the circumference of the first microring filter, n is the effective refractive index of the first microring filter, and m is a positive integer. In other words, only light beams that meet the resonance conditions of the first microring filter 909 can be filtered out by the first microring filter 909 and coupled to the second straight optical waveguide.

[0144] When the light beam reaches the third coupling region between the second straight optical waveguide and the second microring filter 910, a portion of the light beam couples into the second microring filter 910, while the remaining portion of the light beam is output from the second output end of the second straight optical waveguide. After entering the second microring filter 910, the light beam passes through the fourth coupling region formed by the third straight optical waveguide and the second microring filter 910, and a portion of the light beam couples into the third straight optical waveguide, while the remaining portion of the light beam continues to propagate within the second microring filter 910. When the light beam propagating within the second microring filter 910 meets the resonance condition mλ = nl of the second microring filter 910, resonance occurs, resulting in coherence enhancement. The optical power of the light beam received from the second microring filter 910 by the third straight optical waveguide also increases, while light that does not meet the resonance condition is output from the second output end of the second straight optical waveguide. Here, λ is the wavelength of the light beam, l is the circumference of the second microring filter, n is the effective refractive index of the second microring filter, and m is a positive integer. That is, only the light beam that meets the resonance condition of the second microring filter 910 can be screened out by the second microring filter 910 and coupled to the third straight optical waveguide. At this time, the light beam received by the third straight optical waveguide is a light beam with a specific wavelength.

[0145] The above is the process of filtering out a specific wavelength light beam by first passing through the first microring filter 909 and then passing through the second microring filter 910. Similarly, the process of filtering out a specific wavelength light beam by first passing through the second microring filter 910 and then passing through the first microring filter 909 is as follows:

[0146] A light beam within a wavelength range is incident on the input end of the third straight optical waveguide (the end near the power divider 908). When the light beam reaches the fourth coupling region between the third straight optical waveguide and the second microring filter 910, a portion of the light beam is coupled into the second microring filter 910, and the remaining portion of the light beam is output from the output end of the third straight optical waveguide (the end away from the power divider 908). The light beam that enters the second microring filter 910 and propagates through the third coupling region formed by the second straight optical waveguide and the second microring filter 910 is partially coupled into the second straight optical waveguide, while the remaining portion of the light beam continues to propagate within the second microring filter 910. When the light beam propagating within the second microring filter 910 meets the resonance condition mλ = nl of the second microring filter 910, resonance occurs, resulting in coherence enhancement. The optical power received by the second straight optical waveguide from the second microring filter 910 is also increased, while light that does not meet the resonance condition is output from the output end of the third straight optical waveguide.

[0147] When the light beam propagates through the second coupling region between the second straight optical waveguide and the first microring filter 909, a portion of the light beam couples into the first microring filter 909, while the remaining portion of the light beam is output from the first output end of the second straight optical waveguide. After entering the first microring filter 909 and passing through the first coupling region formed by the first straight optical waveguide and the first microring filter 909, a portion of the light beam couples into the first straight optical waveguide, while the remaining portion of the light beam continues to propagate within the first microring filter 909. When the light beam propagating through the first microring filter 909 meets the resonance condition mλ = nl of the first microring filter 909, resonance occurs, resulting in coherence enhancement. The optical power of the light beam received by the first straight optical waveguide from the first microring filter 909 also increases, while light that does not meet the resonance condition is output from the second output end of the second straight optical waveguide. At this point, the light beam received by the first straight optical waveguide is a light beam of a specific wavelength.

[0148] In some embodiments, the first microring filter 909 and the second microring filter 910 are both microring structures, but have different circumferences. According to the resonance conditions, the wavelengths of the light beams filtered out by the first microring filter 909 and the second microring filter 910 are different. Due to the vernier effect, the light beam filtered out by the wavelength tuning chip 9031 is a light beam of a specific wavelength only when the light beam filtered out by the first microring filter 909 coincides with the light beam filtered out by the second microring filter 910.

[0149] The first microring filter 909 and the second microring filter 910 can adopt a strip waveguide or ridge waveguide structure. By adjusting the circumference of the two microring filters, the requirements of different wavelength tuning ranges can be met. Usually, a heater is integrated above the microring filter to change the refractive index of the microring filter through the heater, thereby achieving tuning of different working wavelengths.

[0150] The first microring filter 909 and the second microring filter 910 are capable of filtering a specific wavelength beam from a wavelength range of light emitted by the semiconductor gain chip 9032. This wavelength is determined by the characteristics of the first microring filter 909 and the second microring filter 910. However, the resonant cavity formed by the semiconductor gain chip 9032 and the wavelength tuning chip 9031 selectively supports multiple light beams of different wavelengths based on its cavity structure. The multiple wavelengths supported by the resonant cavity and the beams filtered by the two microring filters do not necessarily overlap. If the multiple wavelengths supported by the resonant cavity do not overlap with the specific wavelength beams filtered by the two microring filters, the refractive index of the phase modulator 907 can be changed to change the cavity length of the phase modulator 907, thereby changing the cavity length of the resonant cavity. This allows the wavelength supported by the resonant cavity to overlap with the specific wavelength beam, thereby causing the resonant cavity to emit the specific wavelength beam.

[0151] However, since the first microring filter 909 and the second microring filter 910 are silicon microrings, the silicon material has a large third-order nonlinear optical susceptibility, and the internal silicon waveguide may lead to excessively high optical power density due to its own high refractive index difference and small cross-sectional size, resulting in the existence of two-photon absorption effect (TPA) in the microring filter. In particular, when the silicon microring filter is used as a laser resonant cavity, the internal optical power is very high. At this time, the two-photon absorption effect will be very significant. The two-photon absorption effect will generate a large number of electron-hole pairs (free carriers). When the free carriers are absorbed, heat will be generated, which will in turn change the refractive index of the resonant cavity, thereby causing the output wavelength of the laser component 901 to have an unstable oscillation field, limiting its application in practical scenarios.

[0152] Figure 11 is a structural diagram of a microring filter in an optical module according to some embodiments of the present disclosure, and Figure 12 is a cross-sectional diagram of a microring filter in an optical module according to some embodiments of the present disclosure. As shown in Figures 11 and 12, to address the nonlinear effects of a silicon optical resonator as a laser resonator under high optical power, the microring filter employs a ridge waveguide structure. Ions are implanted in the slab regions on both sides of the waveguide to form a PN junction. By applying a reverse bias to the PN junction to generate an electric field, the PN junction can rapidly absorb electron-hole pairs generated by two-photon absorption, thereby eliminating wavelength oscillation in laser assembly 901.

[0153] The first microring filter 909 and the second microring filter 910 have the same structure, but different circumferences. By adjusting the circumferences of the two microring filters, requirements for different wavelength tuning ranges can be met.

[0154] Referring to FIG11 , the first microring filter 909 is a ring filter. A transverse cross-section of the ring filter reveals that the ring filter includes a silicon waveguide ridge region 9104, a first slab region 9105, a second slab region 9106, and contact electrodes. The first slab region 9105 is located outside the silicon waveguide ridge region 9104 and surrounds the first slab region 9105. The second slab region 9106 is located inside the silicon waveguide ridge region 9104 and surrounds the second slab region 9106. Thus, from the inside out, the second slab region 9106, the silicon waveguide ridge region 9104, and the first slab region 9105 are arranged in that order.

[0155] An N-type doped region 9107 is provided in the first flat plate region 9105, and the N-type doped region 9107 surrounds the silicon waveguide ridge region 9104; a P-type doped region 9108 is provided in the second flat plate region 9106, and the silicon waveguide ridge region 9104 surrounds the P-type doped region 9108, so that the N-type doped region 9107 and the P-type doped region 9108 surround the silicon waveguide ridge region 9104.

[0156] The N-type doped region 9107 is electrically connected to the P-type doped region 9108 and the contact electrode so as to supply power to the N-type doped region 9107 and the P-type doped region 9108 through the contact electrode, so that the N-type doped region 9107 and the P-type doped region 9108 form a PN junction. The electric field formed by the PN junction surrounds the silicon waveguide ridge region 9104, so that the PN junction absorbs the electron-hole pairs in the silicon waveguide ridge region 9104, the first flat plate region 9105 and the second flat plate region 9106, thereby preventing the electron-hole pair load from generating heat that affects the refractive index of the resonant cavity, thereby eliminating the wavelength oscillation phenomenon caused by the two-photon absorption effect.

[0157] 12 , the first microring filter 909 is a ring filter. A longitudinal cross-section of the first microring filter 909 reveals the first microring filter 909 to include a silicon substrate 9101, a covering layer 9103, a silicon waveguide ridge region 9104, a first slab region 9105, and a second slab region 9106. The covering layer 9103 is disposed above the silicon substrate 9101 along the epitaxial growth direction. The silicon substrate 9101 may be made of silicon material, and the covering layer 9103 may be made of silicon oxide material. The covering layer 9103 is formed by deposition of a thin film of silicon dioxide material.

[0158] The silicon waveguide ridge region 9104 is located in the cover layer 9103. The silicon waveguide ridge region 9104 is used to transmit the light beam coupled into the first microring filter 909. Since the silicon waveguide ridge region 9104 absorbs photons to transmit the light beam, the optical power of the light beam transmitted by the silicon waveguide ridge region 9104 is relatively high, resulting in a large number of electron-hole pairs in the silicon waveguide ridge region 9104 and the first slab region 9105 and the second slab region 9106 on both sides of the silicon waveguide ridge region 9104.

[0159] The first flat plate region 9105 is located on one side of the silicon waveguide ridge region 9104. One side of the first flat plate region 9105 is connected to the edge of one side of the silicon waveguide ridge region 9104. An N-type doped region 9107 is provided in the first flat plate region 9105. That is, N-type ions are injected into the first flat plate region 9105 to form an N-type doped region 9107 in the first flat plate region 9105.

[0160] The second flat plate region 9106 is located on the other side of the silicon waveguide ridge region 9104. One side of the second flat plate region 9106 is connected to the edge of the other side of the silicon waveguide ridge region 9104. A P-type doped region 9108 is provided in the second flat plate region 9106. That is, P-type ions are injected into the second flat plate region 9106 to form a P-type doped region 9108 in the second flat plate region 9106. The P-type doped region 9108 and the N-type doped region 9107 can form a PN junction.

[0161] The N-type doped region 9107 in the first slab region 9105 and the P-type doped region 9108 in the second slab region 9106 form a PN junction. The PN junction surrounds the silicon waveguide ridge region 9104 and part of the first slab region 9105 and part of the second slab region 9106 connected to the silicon waveguide ridge region 9104, so that the electric field formed by the PN junction passes through the silicon waveguide ridge region 9104, thereby causing the PN junction to absorb electron-hole pairs in the silicon waveguide ridge region 9104, the first slab region 9105 and the second slab region 9106.

[0162] In some embodiments, there is a first preset distance between the N-type doped region 9107 and the edge of the silicon waveguide ridge region 9104 facing the first flat plate region 9105 (the right edge shown in Figure 12), and there is a second preset distance between the P-type doped region 9108 and the edge of the silicon waveguide ridge region 9104 facing the second flat plate region 9106 (the left edge shown in Figure 12). The first preset distance and the second preset distance may be equal, so that the first flat plate region 9105 and the second flat plate region 9106 are symmetrically arranged on both sides of the silicon waveguide ridge region 9104.

[0163] In some embodiments, the first preset distance and the second preset distance range from 500 nm to 1 μm.

[0164] In some embodiments, the first predetermined distance and the second predetermined distance are 0.8 μm, so that the electric field formed by the PN junction can quickly absorb electron-hole pairs generated by the two-photon absorption effect.

[0165] In some embodiments, in order to apply voltage to the PN junction, the first microring filter 909 further includes a contact electrode, through which power is supplied to the PN junction; the contact electrode includes a first contact electrode 9109 and a second contact electrode 9110, and the first contact electrode 9109 and the second contact electrode 9110 are located in the covering layer 9103. Along the epitaxial growth direction, the first contact electrode 9109 is arranged above the first flat plate region 9105, and the first contact electrode 9109 is close to the N-type doped region 9107 to facilitate powering the N-type doped region 9107 through the first contact electrode 9109.

[0166] Along the epitaxial growth direction, the second contact electrode 9110 is disposed above the second flat plate region 9106 , and the second contact electrode 9110 is close to the P-type doping region 9108 to facilitate power supply to the P-type doping region 9108 through the second contact electrode 9110 .

[0167] In some embodiments, the width dimension of the first flat plate region 9105 may be the same as the width dimension of the second flat plate region 9106, the width dimension of the first flat plate region 9105 is larger than the width dimension of the silicon waveguide ridge region 9104, the width dimension of the N-type doped region 9107 is smaller than the width dimension of the first flat plate region 9105, the width dimension of the P-type doped region 9108 is smaller than the width dimension of the second flat plate region 9106, the width dimension of the N-type doped region 9107 is the same as the width dimension of the P-type doped region 9108, the width dimension of the first contact electrode 9109 may be equal to or slightly larger than the width dimension of the N-type doped region 9107, and the width dimension of the second contact electrode 9110 may be equal to or slightly larger than the width dimension of the P-type doped region 9108.

[0168] The first contact electrode 9109 can be electrically connected to a power chip on the circuit board 300 via bonding wires, allowing the first contact electrode 9109 to be connected to a first voltage. The second contact electrode 9110 can also be electrically connected to a power chip on the circuit board 300 via bonding wires, allowing the second contact electrode 9110 to be connected to a second voltage. The first voltage is greater than the second voltage, that is, the first contact electrode 9109 is connected to a high voltage and the second contact electrode 9110 is connected to a low voltage, thereby applying a reverse bias to the PN junction. Under reverse bias, the PN junction generates an electric field, allowing the PN junction to quickly absorb electron-hole pairs generated by the two-photon absorption effect.

[0169] If a forward bias is applied to the PN junction through the first contact electrode 9109 and the second contact electrode 9110, the electric field formed by the PN junction will be strong, which will absorb the photons transmitted in the silicon waveguide ridge region 9104, causing the first microring filter 909 to be unable to output light of a specific wavelength.

[0170] In some embodiments, the first slab region 9105 and the second slab region 9106 are slab waveguides, which can reduce the transmission loss of the waveguide. Since silicon has a large nonlinear optical susceptibility, the high refractive index difference and small cross-sectional size of the silicon waveguide itself may lead to excessively high power density, causing strong two-photon absorption effect and free carrier absorption effect. The first slab region 9105 and the second slab region 9106 are respectively arranged on both sides of the silicon waveguide ridge region 9104, and an N-type doped region 9107 is arranged in the first slab region 9105, and a P-type doped region 9108 is arranged in the second slab region 9106. The P-type doped region 9108 is electrically connected to the N-type doped region 9107 to form a PN junction. A reverse bias is applied to the PN junction to form an electric field, so that the PN junction can absorb free carriers, thereby reducing the lifetime of free carriers in the microring filter, thereby reducing the heat generated by the free carrier absorption effect.

[0171] In some embodiments, the first microring filter 909 further includes a buried layer 9102, which is disposed above the silicon substrate 9101, and a covering layer 9103 is disposed above the buried layer 9102, i.e., along the epitaxial growth direction, the silicon substrate 9101, the buried layer 9102 and the covering layer 9103 are disposed in sequence, the thickness of the silicon substrate 9101 may be greater than the thickness of the buried layer 9102, and the thickness of the covering layer 9103 may be greater than the thickness of the silicon substrate 9101.

[0172] If the first microring filter 909 is directly set on the silicon substrate 9101, the light field generated by the silicon waveguide ridge region 9104 may leak into the silicon substrate 9101, increasing the substrate leakage loss. However, a buried layer 9102 is set on the silicon substrate 9101, and the silicon waveguide ridge region 9104 is set above the buried layer 9102. The buried layer 9102 can prevent the light field from leaking into the silicon substrate 9101, reducing the substrate leakage loss and ensuring the output optical power of the first microring filter 909.

[0173] In some embodiments, although the microring filter generates heat due to the two-photon absorption effect, which changes the refractive index of the microring filter, the two-photon absorption effect only occurs at higher optical powers. Due to the two-photon absorption effect, the optical power of the microring filter decreases, which reduces the number of electron-hole pairs and dissipates the heat generated by the movement of the electron-hole pairs. Therefore, the heat generated by the two-photon absorption effect in the microring filter is unstable and cannot be used to stably change the cavity length of the resonant cavity, resulting in unstable oscillation of the output wavelength of the microring filter. To eliminate the wavelength oscillation caused by the two-photon absorption effect in the microring filter, it is necessary to absorb the electron-hole pairs through the PN junction.

[0174] In some embodiments, in order to stably change the cavity length of the resonant cavity, the first microring filter 909 further includes a heater 920. The heater 920 is disposed above the covering layer 9103 along the epitaxial growth direction. The heater 920 can be electrically connected to a power chip on the circuit board 300 through bonding to supply power and generate heat to heat the covering layer 9103, thereby changing the refractive index of the first microring filter 909.

[0175] In some embodiments, the wavelength tuning chip 9031 further includes a plurality of absorbers, which are used to absorb the optical power of useless light beams to avoid reflection and generation of stray light.

[0176] The wavelength tuning chip 9031 includes a first absorber 911, a second absorber 912, a third absorber 913 and a fourth absorber 914. The power divider 908 is connected to the input end of the first straight optical waveguide, the first absorber 911 is connected to the output end of the first straight optical waveguide, the second absorber 912 is connected to the first output end of the second straight optical waveguide, the third absorber 913 is connected to the second output end of the second straight optical waveguide, the power divider 908 is connected to the input end of the third straight optical waveguide, and the fourth absorber 914 is connected to the output end of the third straight optical waveguide.

[0177] The first absorber 911 is used to absorb other light beams in the first straight light waveguide except those passing through the first microring filter 909 and the second microring filter 910. The second absorber 912 and the third absorber 913 are used to absorb other light beams in the second straight light waveguide except those passing through the first microring filter 909 and the second microring filter 910. The fourth absorber 914 is used to absorb other light beams in the third straight light waveguide except those passing through the first microring filter 909 and the second microring filter 910.

[0178] 9 , in some embodiments, the wavelength tuning chip 9031 further includes a phase modulator 907, which is located between the input coupler 906 and the power divider 908. One end of the phase modulator 907 is connected to the input coupler 906, and the other end of the phase modulator 907 is connected to the input end of the power divider 908. The phase modulator 907 is used to adjust the wavelength of the light beam supported by the resonant cavity so that the specific wavelength light beam filtered by the first microring filter 909 and the second microring filter 910 coincides with the light beam in the resonant cavity.

[0179] The phase modulator 907 may be provided with a heater. By changing the heater, the cavity length of the phase modulator 907 is changed, thereby changing the cavity length of the resonant cavity, so that a light beam of a certain wavelength supported by the resonant cavity coincides with a light beam of a specific wavelength screened by the two microring filters.

[0180] In some embodiments, the first microring filter 909, the second microring filter 910, and the phase modulator 907 form a wavelength-tunable component. The first microring filter 909 and the second microring filter 910 can filter out a light beam of a specific wavelength from a wavelength range of light emitted by the semiconductor gain chip 9032. This wavelength is determined by the characteristics of the first microring filter 909 and the second microring filter 910. However, the resonant cavity formed by the semiconductor gain chip 9032 and the silicon photonic chip can selectively support multiple light beams of different wavelengths based on its cavity structure. The multiple wavelengths supported by the resonant cavity and the light beams filtered by the two microring filters do not necessarily overlap.

[0181] If the multiple wavelengths of light beams supported by the resonant cavity do not overlap with the specific wavelength light beams screened out by the two microring filters, the cavity length of the phase modulator 907 can be changed by changing the refractive index of the phase modulator 907, thereby changing the cavity length of the resonant cavity, so that the light beam of a certain wavelength supported by the resonant cavity overlaps with the specific wavelength light beam, so that the resonant cavity emits a light beam of the specific wavelength.

[0182] FIG13 is a light path diagram of a light source assembly in an optical module according to some embodiments of the present disclosure. As shown in FIG13 , when the laser assembly 901 is used as a light source, the semiconductor gain chip 9032 emits light within a wavelength range. The light is then incident on the wavelength tuning chip 9031 through the input coupler 906. The input light is split by the power splitter 908 and then enters the first microring filter 909 and the second microring filter 910. After the split light passes through the first microring filter 909, wavelengths that meet FSR1 are selected to pass through the first microring filter 909, and the wavelength period meets FSR1. The filtered light then passes through the second microring filter 910, and wavelengths that meet FSR2 are selected to pass through the second microring filter 910, and the wavelength period meets FSR2. Only wavelengths that meet both FSR1 and FSR2 are output by the second microring filter 910. The light beam output by the second microring filter 910 is transmitted to the semiconductor gain chip 9032 through the power splitter 908 and the input coupler 906. The light beam is reflected back and forth between the semiconductor gain chip 9032 and the wavelength tuning chip 9031, thereby achieving stable output of a specific wavelength light beam from the semiconductor gain chip 9032.

[0183] The specific wavelength light beam output by the semiconductor gain chip 9032 is converted into collimated light by the first lens 9033. The collimated light directly passes through the isolator 9034 and enters the second lens 9035. The second lens 9035 converges the collimated light that has passed through the isolator 9034 onto the semiconductor amplifier chip 9036. The semiconductor amplifier chip 9036 amplifies the power of the specific wavelength light beam. The amplified light is converted into collimated light by the third lens 9037. The collimated light is split into two beams by the beam splitter 9038. One beam is coupled into the internal fiber adapter 902 and transmitted to the coherent optical chip 1100 through the internal fiber adapter 902. The other beam is emitted into the power monitor 9039. The power monitor monitors the optical power of the specific wavelength light beam in real time to ensure that the optical power of the specific wavelength light beam is within a preset optical power range.

[0184] The optical module provided by the present disclosure adopts a silicon filter and a silicon photonics tunable wavelength tuning chip. The silicon filter adopts a microring resonant cavity structure and forms a PN junction by ion implantation on both sides of the microring waveguide. Compared with a microring resonant cavity without an integrated PN junction, applying a reverse bias to the PN junction can quickly absorb the electron-hole pairs generated by the nonlinear effect of silicon under high power, thereby eliminating the wavelength oscillation phenomenon caused by the nonlinear effect, and realizing a high-power, narrow-linewidth, widely tunable silicon photonics integrated laser, which is convenient for application in coherent optical communications, lidar, sensing and other fields.

[0185] The disclosed embodiments also provide an optical module with another structure, which includes not only a circuit board, a light source, an optical chip, a fiber adapter, and an optical fiber connecting the optical chip and the fiber adapter, but also a coupler assembly. The coupler assembly in this embodiment can be disposed between the optical chip and the optical fiber (receiving fiber, transmitting fiber) to achieve the transmission and reception of modulated light. Of course, the above-mentioned coupler assembly can also be disposed on other components, such as the optical chip. For details, please refer to the following examples.

[0186] Figure 14 is a partial structural diagram of an optical module provided according to some embodiments of the present disclosure. As shown in Figure 14, an optical chip 400 is disposed on a circuit board 300. The optical chip 400 is electrically connected to the circuit board 300, for example, by wire bonding. The periphery of the optical chip 400 is connected to the circuit board 300 via multiple conductive lines. Therefore, the optical chip 400 is generally disposed on the surface of the circuit board 300.

[0187] The optical chip 400 and the light source 500 can be optically connected through a first optical fiber ribbon. The optical chip 400 receives light from the light source 500 through the optical fiber ribbon, and the optical chip 400 modulates the light. The optical chip 400 and the light source 500 can also be directly end-face coupled. The optical chip 400 directly receives light from the light source 500, and the optical chip 400 modulates the light.

[0188] The optical chip 400 and the fiber adapter 700 can be optically connected via a transmitting optical fiber and a receiving optical fiber. The fiber adapter 700 also optically connects to the optical fiber outside the optical module. Light modulated by the optical chip 400 is transmitted via the transmitting optical fiber to the fiber adapter 700, and then to the external optical fiber to transmit the light. Light transmitted by the external optical fiber is then transmitted via the fiber adapter 700 to the receiving optical fiber, which then transmits the light to the optical chip 400. The optical chip 400 converts the received optical signal into an electrical signal to receive the light.

[0189] In some embodiments, the optical chip 400 is a silicon photonic chip, which is provided with an input optical port, an output optical port, a monitoring optical port, a high-speed electrical signal interface, and a DC bias signal interface, etc., wherein the input optical port includes a first input optical port and a second input optical port. The first input optical port is used to couple the light output by the light source 500 into the silicon photonic chip, the second input optical port is used to couple the signal light transmitted by the optical fiber outside the optical module into the silicon photonic chip, and the output optical port is used to couple the signal light modulated by the silicon photonic chip out of the optical chip 400.

[0190] When the optical chip 400 is coupled with the transmitting optical fiber and the receiving optical fiber, common coupling methods include end-face coupling and grating coupling. Among them, the grating coupling method is easy to process and has a larger light spot, but has limitations such as large insertion loss and wavelength sensitivity. In the end-face coupling method, due to the large refractive index difference between silicon and silicon dioxide or air, the silicon waveguide has a strong ability to limit the light field. The size of the silicon waveguide can be made into a very small size, and its cross-sectional size is usually less than 0.5 microns, while the core diameter size of an ordinary single-mode optical fiber is about 8-10 microns. The size difference between the two is large, resulting in serious mode field mismatch, which leads to large coupling loss.

[0191] Traditional spot-size converters (SSCs) need to prevent light from leaking into the silicon wafer substrate. This typically requires a substrate hollowing process to form a suspended waveguide structure, which often presents greater reliability risks than solid waveguide structures. A common solid SSC design approach is to slightly reduce the mode spot size to approximately 6μm, which effectively reduces substrate leakage loss. However, compared to the standard single-mode fiber mode spot size (9-10μm), there is still a significant mode mismatch loss of approximately 1dB.

[0192] In order to solve the above problems, the present disclosure provides an optical module, which proposes a low-loss solid large-mode spot SSC design, which can avoid the use of a substrate hollowing process and enhance the installation reliability of the waveguide. At the same time, the use of a multi-layer cladding oxide structure design with different refractive indices can further reduce the substrate leakage loss of the solid waveguide and achieve ultra-low coupling insertion loss with a standard single-mode optical fiber.

[0193] Figure 15 is a transverse cross-sectional view of an end-face coupler in an optical module according to some embodiments of the present disclosure. As shown in Figures 14 and 15, the optical module provided by the embodiments of the present disclosure further includes a coupler assembly, which may be a waveguide coupler 1200. The waveguide coupler 1200 is an end-face coupler located between the optical chip 400 and the transmitting optical fiber, and between the optical chip 400 and the receiving optical fiber. The waveguide coupler 1200 couples the optical chip 400 with the transmitting optical fiber, thereby coupling the modulated signal light of the optical chip 400 to the transmitting optical fiber through the waveguide coupler 1200 to achieve transmission of the modulated light; and the waveguide coupler 1200 couples the signal light transmitted by the receiving optical fiber to the optical chip 400 to achieve reception of light.

[0194] In which, the waveguide coupler 1200 includes a substrate 1201, a first cladding 1202 and a second cladding 1203. Along the epitaxial growth direction, the first cladding 1202 is arranged on the substrate 1201, and the second cladding 1203 is arranged on the first cladding 1202, so that the substrate 1201, the first cladding 1202 and the second cladding 1203 are arranged in sequence along the epitaxial growth direction.

[0195] In some embodiments, substrate 1201 is a silicon-on-insulator (SOI) substrate. SOI substrates are commonly used substrates for silicon-based devices. SOI substrates typically include a silicon substrate and a buried oxide layer disposed on the silicon substrate. The buried oxide layer is typically 3 μm thick. It should be noted that a complete SOI substrate typically also includes a top layer of silicon disposed on the buried oxide layer. The top layer of silicon is typically 220 nm thick. However, during the fabrication of the end coupler, to prevent light from being drawn into the top layer of silicon, the top layer of silicon is removed to expose the buried oxide layer. Processing is then performed on the buried oxide layer.

[0196] The first cladding layer 1202 is disposed on a side of the buried oxide layer opposite to the silicon substrate. The first cladding layer 1202 may be a silicon dioxide cladding layer. The refractive index of the first cladding layer 1202 is smaller than the refractive index of the substrate 1201 .

[0197] The second cladding layer 1203 is disposed on the side of the first cladding layer 1202 opposite the substrate 1201, thereby supporting the second cladding layer 1203 via the first cladding layer 1202. The second cladding layer 1203 can be a silicon nitride cladding layer, and the refractive index of the second cladding layer 1203 is greater than the refractive index of the first cladding layer 1202. As such, along the epitaxial growth direction, the refractive index of the waveguide coupler 1200 first decreases and then increases, thereby achieving better longitudinal confinement of the light field and preventing light within the second cladding layer 1203 from leaking into the substrate 1201.

[0198] In some embodiments, the thickness of the first cladding 1202 is a first thickness H1, and the thickness of the second cladding 1203 is a second thickness H2. The second thickness H2 is greater than the first thickness H1 to facilitate the arrangement of a coupling waveguide in the second cladding 1203.

[0199] In some embodiments, the first thickness H1 ranges from 2 to 3 μm, and the second thickness H2 ranges from 6 to 10 μm.

[0200] The second cladding 1203 has a first end face 1208 optically coupled to the optical fiber and a second end face 1209 optically coupled to the optical chip 400. A coupling waveguide may be provided in the second cladding 1203, with one end of the coupling waveguide adjacent to the first end face 1208 and the other end of the coupling waveguide adjacent to the second end face 1209, so that one end of the coupling waveguide is coupled to the optical fiber to receive the optical signal, and the coupling waveguide can directionally transmit the optical signal along its own extension direction. The coupling waveguide couples the transmitted optical signal to the optical chip 400, thereby realizing the coupling connection between the optical chip 400 and the optical fiber through the coupling waveguide.

[0201] The coupling waveguide can be a tapered waveguide. The end of the coupling waveguide used for coupling to the optical fiber is called the tip, and the end of the coupling waveguide used for connecting to the optical chip 400 is called the tail. The tip is smaller to match the mode field of the optical fiber, while the tail is larger to match the optical chip 400. In actual design, the widths of the tip and tail, as well as the overall thickness of the coupling waveguide, can be designed according to actual needs.

[0202] The coupling waveguides in the second cladding 1203 include a first coupling waveguide 1204 and a second coupling waveguide 1205. One end of the first coupling waveguide 1204 is close to the first end face 1208, so that the first coupling waveguide 1204 is coupled to the optical fiber, and the first coupling waveguide 1204 is used to confine the light transmitted by the optical fiber to a mode field of a predetermined size; one end of the second coupling waveguide 1205 is close to the second end face 1209, so that the second coupling waveguide 1205 is optically connected to the optical chip 400, and the second coupling waveguide 1205 is used to couple the light confined by the first coupling waveguide 1204 within the predetermined mode field into the optical chip 400; the first coupling waveguide 1204 and the second coupling waveguide 1205 are coupled to each other, thereby realizing optical coupling between the optical fiber and the optical chip 400 through the first coupling waveguide 1204 and the second coupling waveguide 1205.

[0203] In some embodiments, when the waveguide coupler 1200 achieves a coupling connection between the optical fiber and the optical chip 400 via the first coupling waveguide 1204 and the second coupling waveguide 1205, the position of the first coupling waveguide 1204 within the second cladding 1203 must correspond to the optical fiber. When the gap between the first coupling waveguide 1204 and the second coupling waveguide 1205 exceeds a preset range, that is, when the optical fiber is positioned higher, the first coupling waveguide 1204 is farther from the substrate 1201, which affects the coupling efficiency between the first coupling waveguide 1204 and the second coupling waveguide 1205. To improve the coupling efficiency between the first coupling waveguide 1204 and the second coupling waveguide 1205, a transition waveguide may be provided between the first coupling waveguide 1204 and the second coupling waveguide 1205. The transition waveguide is used to gradually transition the light field with a higher end face in the waveguide coupler 1200 to the lower waveguide layer, ultimately reaching the coupling waveguide closer to the substrate 1201.

[0204] The waveguide coupler 1200 includes at least one transition waveguide, which is located between a first coupling waveguide 1204 and a second coupling waveguide 1205. A first gap is provided between the first coupling waveguide 1204 and the at least one transition waveguide, and a second gap is provided between the second coupling waveguide 1205 and the at least one transition waveguide.

[0205] Since the larger the gap between waveguides, the greater the coupling difficulty, the second gap G2 is smaller than the first gap G1 to reduce the coupling difficulty between the first coupling waveguide 1204, the at least one transition waveguide, and the second coupling waveguide 1205. This allows the higher light field at the first end face 1208 to gradually transition to the at least one transition waveguide through the first coupling waveguide 1204 and ultimately reach the second coupling waveguide 1205. During the light field transition process, leakage of the light field in the second cladding 1203 to the substrate 1201 is prevented.

[0206] In order to couple the optical signal transmitted by the first coupling waveguide 1204 into the at least one transition waveguide, and the optical signal transmitted by the at least one transition waveguide into the second coupling waveguide 1205, a first overlapping portion is provided between the first coupling waveguide 1204 and the at least one transition waveguide, and a second overlapping portion is provided between the second coupling waveguide 1205 and the at least one transition waveguide. The length of the second overlapping portion is shorter than the length of the first overlapping portion, so as to ensure the coupling efficiency among the first coupling waveguide 1204, the at least one transition waveguide, and the second coupling waveguide 1205, and reduce the leakage of the light field in the second cladding 1203 to the substrate 1201.

[0207] 15 , in some embodiments, the waveguide coupler 1200 may include a first transition waveguide 1206 and a second transition waveguide 1207. The first transition waveguide 1206 and the second transition waveguide 1207 are located in the second cladding 1203. Along the epitaxial growth direction, the first transition waveguide 1206 is located between the first coupling waveguide 1204 and the second coupling waveguide 1205. The second transition waveguide 1207 is located between the first transition waveguide 1206 and the second coupling waveguide 1205. One end of the first coupling waveguide 1204 is coupled to the optical fiber. The other end of the coupling waveguide 1204 is coupled and connected to one end of the first transition waveguide 1206, the other end of the first transition waveguide 1206 is coupled and connected to one end of the second transition waveguide 1207, the other end of the second transition waveguide 1207 is coupled and connected to one end of the second coupling waveguide 1205, and the other end of the second coupling waveguide 1205 is optically connected to the optical chip 400, so as to realize the coupling connection between the optical fiber and the optical chip 400 through the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207 and the second coupling waveguide 1205.

[0208] In some embodiments, a third height H3 is provided between the second transition waveguide 1207 and the upper surface of the substrate 1201, a fourth height H4 is provided between the first transition waveguide 1206 and the upper surface of the substrate 1201, a fifth height H5 is provided between the first coupling waveguide 1204 and the upper surface of the substrate 1201, the second coupling waveguide 1205 is adjacent to the first cladding 1202, the fifth height H5 is greater than the fourth height H4, and the fourth height H4 is greater than the third height H3.

[0209] A first gap G1 is defined between the first coupling waveguide 1204 and the first transition waveguide 1206, a second gap G2 is defined between the second coupling waveguide 1205 and the second transition waveguide 1207, and a third gap G3 is defined between the first transition waveguide 1206 and the second transition waveguide 1207. Since the larger the gap between waveguides, the greater the coupling difficulty, to reduce the coupling difficulty between the first coupling waveguide 1204 and the first transition waveguide 1206, the first transition waveguide 1206 and the second transition waveguide 1207, and the second transition waveguide 1207 and the second coupling waveguide 1205, the first gap G1 is larger than the second gap G2, and the third gap G3 is larger than the second gap G2. This allows the higher optical field at the first end face 1208 to gradually transition to the first transition waveguide 1206 and the second transition waveguide 1207, and ultimately to the second coupling waveguide 1205. During the optical field transition process, leakage of the optical field in the second cladding 1203 into the substrate 1201 is prevented.

[0210] In some embodiments, the size range of the third height H3 is 2 to 4 μm, the size range of the fourth height H4 is 3 to 6 μm, the size range of the fifth height H5 is 3 to 6 μm, the size range of the first gap G1 is 0.5 to 2 μm, the size range of the second gap G2 is 0.1 to 0.8 μm, and the size range of the third gap G3 is 0.5 to 2 μm.

[0211] In some embodiments, the first gap G1 may be larger than the third gap G3, so that the first gap G1, the third gap G3 and the second gap G2 gradually decrease, that is, along the light receiving direction, the gap between the waveguides in the waveguide coupler 1200 gradually decreases.

[0212] In some embodiments, the first gap G1 may be smaller than the third gap G3 , and the first gap G1 may be larger than the second gap G2 , so that there is no regularity among the first gap G1 , the third gap G3 , and the second gap G2 .

[0213] In some embodiments, to improve the coupling efficiency between the waveguides, the larger the gap between the waveguides, the longer the overlapping length between the waveguides. Thus, the size of the first gap G1 is 1.3 μm, and the length of the first overlapping portion between the first coupling waveguide 1204 and the first transition waveguide 1206 is 400 μm; the size of the second gap G2 is 0.43 μm, and the length of the second overlapping portion between the second coupling waveguide 1205 and the second transition waveguide 1207 is 100 μm; the size of the third gap is 0.85 μm, and the length of the third overlapping portion between the first transition waveguide 1206 and the second transition waveguide 1207 is 200 μm.

[0214] In some embodiments, the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 are supported on the second cladding 1203 via the first cladding 1202 located thereunder, and are further supported on the substrate 1201 via the second cladding 1203. That is, the second cladding 1203 covering the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 is supported on the substrate 1201 via the first cladding 1202. This allows the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 to be effectively supported by the substrate 1201, thereby avoiding the need for a substrate hollowing process and enhancing the installation reliability of the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205.

[0215] Since the refractive index of the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 is greater than the refractive index of the second cladding 1203, and the refractive index of the second cladding 1203 is greater than the refractive index of the first cladding 1202, the light transmitted by the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 is unlikely to leak from the second cladding 1203 into the first cladding 1202, thereby reducing the leakage of the optical signal into the substrate 1201. This can reduce the substrate leakage loss of the coupling waveguide, which is beneficial to improving the optical signal coupling efficiency from the optical fiber to the optical chip 400.

[0216] Figure 16 is a top view of an end-face coupler in an optical module according to some embodiments of the present disclosure. As shown in Figure 16, to facilitate mode field matching between first coupling waveguide 1204 and the optical fiber, first coupling waveguide 1204, first transition waveguide 1206, second transition waveguide 1207, and second coupling waveguide 1205 are configured to match the modes. These first coupling waveguide 1204, first transition waveguide 1206, second transition waveguide 1207, and second coupling waveguide 1205 all employ a tapered structure.

[0217] The first coupling waveguide 1204 includes a first tapered waveguide 1220 and a second tapered waveguide 1221. The tip of the first tapered waveguide 1220 is adjacent to the first end face 1208, and the tip of the second tapered waveguide 1221 is opposite to the tip of the first tapered waveguide 1220. That is, the tip of the first tapered waveguide 1220 is adjacent to the first end face 1208, and the tip of the second tapered waveguide 1221 is away from the first end face 1208.

[0218] In some embodiments, the tip of the first tapered waveguide 1220 is coupled to a transmitting optical fiber or a receiving optical fiber, and the width of the tip is small, so that the light mode at the tip is distributed into the second cladding 1203, so as to better match the light mode transmitted by the externally coupled optical fiber, that is, the light field distribution at the tip has a better overlap with the light field distribution in the optical fiber and a higher coupling efficiency.

[0219] In some embodiments, the end of the first tapered waveguide 1220 can be directly connected to the end of the second tapered waveguide 1221, and the width of the end is greater than the width of the tip, so that the refractive index of the end is greater than the refractive index of the tip, to facilitate coupling of light from the tip to the end.

[0220] In some embodiments, the first coupling waveguide 1204 may further include a straight waveguide, which connects the first tapered waveguide 1220 and the second tapered waveguide 1221. The width of the straight waveguide is the same as the width of the ends of the first tapered waveguide 1220 and the second tapered waveguide 1221. That is, the end of the first tapered waveguide 1220 is connected to one end of the straight waveguide, and the end of the second tapered waveguide 1221 is connected to the other end of the straight waveguide, so that the first tapered waveguide 1220 and the second tapered waveguide 1221 are connected through the straight waveguide in the middle.

[0221] The first transition waveguide 1206 includes a third tapered waveguide 1240 and a fourth tapered waveguide 1241 connected to each other. The tip of the third tapered waveguide 1240 faces the second tapered waveguide 1221. The third tapered waveguide 1240 and the second tapered waveguide 1221 have an overlapping portion. The first transition waveguide 1206 is used to receive the optical signal transmitted by the first coupling waveguide 1204.

[0222] The second transition waveguide 1207 includes a fifth tapered waveguide 1250 and a sixth tapered waveguide 1251 connected to each other. The tip of the fifth tapered waveguide 1250 faces the fourth tapered waveguide 1241. The fifth tapered waveguide 1250 and the fourth tapered waveguide 1241 have an overlapping portion. The second transition waveguide 1207 is used to receive the optical signal transmitted by the first transition waveguide 1206.

[0223] The second coupling waveguide 1205 includes a seventh tapered waveguide 1230 and a straight waveguide 1231. The tip of the seventh tapered waveguide 1230 is directed toward the sixth tapered waveguide 1251. The seventh tapered waveguide 1230 and the sixth tapered waveguide 1251 have overlapping portions. The second coupling waveguide 1205 is used to receive the optical signal transmitted by the second transition waveguide 1207 and couple the optical signal to the optical chip 400.

[0224] The end of the seventh tapered waveguide 1230 is connected to the straight waveguide 1231 , which is adjacent to the second end face 1209 . The light field in the seventh tapered waveguide 1230 is coupled to the straight waveguide 1231 , which couples the optical signal to the optical chip 400 to achieve light reception.

[0225] In some embodiments, the first coupling waveguide 1204 may be a silicon nitride waveguide, and the second coupling waveguide 1205 may be a silicon waveguide. The refractive index of silicon nitride is approximately 2.0. Compared with silicon, the refractive index of silicon nitride is smaller, and the silicon nitride waveguide that can be manufactured is larger in size, thereby reducing the coupling loss between the first coupling waveguide 1204 and the single-mode optical fiber. In addition, silicon nitride has lower transmission loss. Using silicon nitride to prepare the silicon nitride waveguide can reduce the transmission loss between the first coupling waveguide 1204 and the single-mode optical fiber.

[0226] Figure 17 is a cross-sectional view along AA in Figure 16 , Figure 18 is a cross-sectional view along BB in Figure 16 , Figure 19 is a cross-sectional view along CC in Figure 16 , Figure 20 is a cross-sectional view along DD in Figure 16 , and Figure 21 is a cross-sectional view along EE in Figure 16 . As shown in Figures 17-21 , the thickness of first coupling waveguide 1204 is smaller than the thickness of second coupling waveguide 1205 . The cross-sectional dimensions of first coupling waveguide 1204 and second coupling waveguide 1205 may differ. When light is coupled between first coupling waveguide 1204 , first transition waveguide 1206 , second transition waveguide 1207 , and second coupling waveguide 1205 , the different waveguide cross-sections cause a sudden change in the light transmission mode, resulting in loss and polarization-dependent loss. Therefore, a special structure is designed at the coupling point between first coupling waveguide 1204 , first transition waveguide 1206 , second transition waveguide 1207 , and second coupling waveguide 1205 to reduce loss and polarization-dependent loss.

[0227] The width of the second tapered waveguide 1221 of the first coupling waveguide 1204 and the width of the third tapered waveguide 1240 of the first transition waveguide 1206 are designed so that, in the portion where the first coupling waveguide 1204 and the first transition waveguide 1206 overlap, the lateral width of the second tapered waveguide 1221 gradually narrows, while the lateral width of the third tapered waveguide 1240 gradually widens. This allows the light field transmitted in the first coupling waveguide 1204 to be slowly released into the first transition waveguide 1206. This ensures that there is no mode mutation during the coupling process between the first coupling waveguide 1204 and the first transition waveguide 1206, and the mode conversion approximately satisfies the adiabatic condition. That is, both TE polarized light and TM polarized light can be well coupled into the first coupling waveguide 1204 or the first transition waveguide 1206, thereby reducing polarization-dependent loss and improving coupling efficiency.

[0228] The width of the fourth tapered waveguide 1241 of the first transition waveguide 1206 and the width of the fifth tapered waveguide 1250 of the second transition waveguide 1207 are designed so that, in the portion where the first transition waveguide 1206 and the second transition waveguide 1207 overlap, the lateral width of the fourth tapered waveguide 1241 gradually narrows, while the lateral width of the fifth tapered waveguide 1250 gradually widens. This allows the light field transmitted in the first transition waveguide 1206 to be slowly released into the second transition waveguide 1207. This ensures that there is no mode mutation during the coupling process between the first transition waveguide 1206 and the second transition waveguide 1207, and the mode conversion approximately satisfies the adiabatic condition. That is, both TE polarized light and TM polarized light can be well coupled into the first transition waveguide 1206 or the second transition waveguide 1207, thereby reducing polarization-dependent loss and improving coupling efficiency.

[0229] The width of the sixth tapered waveguide 1251 of the second transition waveguide 1207 and the width of the seventh tapered waveguide 1230 of the second coupling waveguide 1205 are designed so that, in the portion where the second transition waveguide 1207 and the second coupling waveguide 1205 overlap, the lateral width of the sixth tapered waveguide 1251 gradually narrows, while the lateral width of the seventh tapered waveguide 1230 gradually widens. This allows the light field transmitted in the second transition waveguide 1207 to be gradually released into the second coupling waveguide 1205. This ensures that there is no mode mutation during the coupling process between the second transition waveguide 1207 and the second coupling waveguide 1205, and the mode conversion approximately satisfies the adiabatic condition. That is, both TE polarized light and TM polarized light can be well coupled into the second transition waveguide 1207 or the second coupling waveguide 1205, thereby reducing polarization-dependent loss and improving coupling efficiency.

[0230] Since the refractive index of the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 is greater than the refractive index of the second cladding 1203, and the refractive index of the second cladding 1203 is greater than the refractive index of the first cladding 1202, the light transmitted by the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205 is unlikely to leak from the second cladding 1203 into the first cladding 1202, thereby reducing the leakage of the optical signal into the substrate 1201. This can reduce the substrate leakage loss of the coupling waveguide, which is beneficial to improving the optical signal coupling efficiency from the optical fiber to the optical chip 400.

[0231] In some embodiments, by adding a first cladding 1202 with a lower refractive index between the second cladding 1203 and the substrate 1201, better longitudinal confinement of the light field in the second cladding 1203 can be achieved. In order to strengthen the horizontal confinement of the light field in the second cladding 1203, side grooves 1210 are provided in the first cladding 1202 and the second cladding 1203. The side grooves 1210 are located on both sides of the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205.

[0232] 16 and 17 , side grooves 1210 are provided on both sides of the first coupling waveguide 1204, the first transition waveguide 1206, the second transition waveguide 1207, and the second coupling waveguide 1205. The side grooves 1210 may be located within the first cladding 1202 and the second cladding 1203, and an opening is formed on the side of the side groove 1210 away from the substrate 1201, thereby forming U-shaped side grooves 1210 on the first cladding 1202 and the second cladding 1203.

[0233] In some embodiments, air grooves are etched on both sides of the first coupling waveguide 1204 and the second coupling waveguide 1205 in the second cladding 1203. During coupling packaging, the air grooves are filled with glue, and the refractive index of the glue is lower than that of the second cladding 1203. The side grooves 1210 are symmetrical with respect to the first coupling waveguide 1204 and the second coupling waveguide 1205, simulating the transverse refractive index distribution of the optical fiber to strengthen the horizontal constraint of the light field.

[0234] Along the width direction of the waveguide coupler 1200, the second cladding 1203 is divided by the side grooves 1210 into two separate parts, namely a central part 1260 and a peripheral part 1261. The central part 1260 is located on the inner side and wraps around the first coupling waveguide 1204 and the second coupling waveguide 1205. The peripheral part 1261 is arranged outside the central part 1260 and also plays a supporting and protective role.

[0235] By providing side grooves 1210 on the second cladding 1203, the mode field distribution formed by the central portion 1260 and the first coupling waveguide 1204 can better match the mode field distribution of the optical fiber within the plane where the waveguide coupler 1200 contacts the optical fiber, thereby reducing the coupling loss at the first end face 1208 where the waveguide coupler 1200 contacts the optical fiber.

[0236] In some embodiments, within the first end face 1208 where the waveguide coupler 1200 contacts the optical fiber, the central portion 1260 and the first coupling waveguide 1204 jointly form a receiving mode field, and the optical fiber has a transmitting mode field. When the receiving mode field distribution and the transmitting mode field distribution match more closely, the optical signal loss decreases. Therefore, the receiving mode field distribution can be changed by adjusting the size of the central portion 1260, i.e., adjusting the width W1 of the side groove 1210, to better match the transmitting mode field distribution in the optical fiber, thereby reducing the optical signal loss.

[0237] In some embodiments, the width dimension W1 of the side trench 1210 is greater than 2 μm.

[0238] The side groove 1210 can adopt a groove structure built on the substrate 1201, that is, the bottom surface of the side groove 1210 is exactly located on the surface of the substrate 1201, so that part of the upper surface of the substrate 1201 can be exposed from the bottom surface of the side groove 1210.

[0239] The bottom surface of the side groove 1210 may also be located in the first cladding layer 1202 , and the bottom surface of the side groove 1210 may also be located in the second cladding layer 1203 , that is, the bottom surface of the side groove 1210 may be at a certain distance from the surface of the substrate 1201 .

[0240] In some embodiments, the bottom surface of the side trench 1210 may further pass through the first cladding layer 1202 and enter the substrate 1201 , that is, the bottom surface of the side trench 1210 is located below the surface of the substrate 1201 .

[0241] In some embodiments, the side groove 1210 may be a polygonal groove, that is, the side groove 1210 may have a polygonal horizontal cross-section, such as a rectangular groove form, a trapezoidal groove form, etc.

[0242] In some embodiments, the medium filled in the side groove 1210 may be air, or may be other dielectric materials having a refractive index lower than that of the second cladding layer 1203 .

[0243] In some embodiments, the side grooves 1210 can be formed directly by a one-step etching process. For example, a first cladding layer 1202 of silicon dioxide can be deposited on the substrate 1201, and a second cladding layer 1203 of silicon nitride can be deposited on the first cladding layer 1202. The first coupling waveguide 1204 and the second coupling waveguide 1205 are formed in the second cladding layer 1203. Then, the side grooves 1210 are formed by etching downward on the surface of the second cladding layer 1203 on both sides of the first coupling waveguide 1204 and the second coupling waveguide 1205.

[0244] Side grooves 1210 are provided on both sides of the first coupling waveguide 1204 and the second coupling waveguide 1205 so that the optical field of the second cladding 1203 can be confined to a range close to the mode field size of the single-mode fiber, achieving optimal mode field matching with a standard single-mode fiber. Compared with a design without side grooves, this can effectively reduce insertion loss.

[0245] In some embodiments, the transition waveguide between the first coupling waveguide 1204 and the second coupling waveguide 1205 may include more than just the first transition waveguide 1206 and the second transition waveguide 1207 , and the number of transition waveguides may be determined according to the position of the optical fiber.

[0246] FIG22 is a second transverse cross-sectional view of an end-face coupler in an optical module according to some embodiments of the present disclosure. As shown in FIG22 , the waveguide coupler 1200 further includes a first transition waveguide 1206. The first transition waveguide 1206 is located within the second cladding 1203 and is located above the second coupling waveguide 1205 along the epitaxial growth direction. The first coupling waveguide 1204 is located above the first transition waveguide 1206. One end of the first coupling waveguide 1204 is coupled to the optical fiber, and the other end of the first coupling waveguide 1204 is coupled to one end of the first transition waveguide 1206. The other end of the first transition waveguide 1206 is coupled to one end of the second coupling waveguide 1205. The second coupling waveguide 1205 is optically connected to the optical chip 400, thereby achieving a coupling connection between the optical fiber and the optical chip 400 through the first coupling waveguide 1204, the first transition waveguide 1206, and the second coupling waveguide 1205.

[0247] In some embodiments, a third height H3 is defined between the first transition waveguide 1206 and the upper surface of the substrate 1201, a fourth height H4 is defined between the first coupling waveguide 1204 and the upper surface of the substrate 1201, and the fourth height H4 is greater than the third height H3. The second coupling waveguide 1205 is adjacent to the first cladding 1202, a first gap G1 is defined between the first coupling waveguide 1204 and the first transition waveguide 1206, a first overlapping portion is defined between the first coupling waveguide 1204 and the first transition waveguide 1206, a second gap G2 is defined between the first transition waveguide 1206 and the second coupling waveguide 1205, and a second overlapping portion is defined between the second coupling waveguide 1205 and the first transition waveguide 1206.

[0248] Since the larger the gap between the waveguides, the greater the coupling difficulty, in order to reduce the coupling difficulty between the first transition waveguide 1206 and the second coupling waveguide 1205, the second gap G2 is smaller than the first gap G1, and the length of the second overlapping portion is smaller than the length of the first overlapping portion, so that the higher light field at the first end face 1208 is gradually transitioned to the first transition waveguide 1206 and finally reaches the second coupling waveguide 1205, and during the light field transition process, the light field in the second cladding 1203 is prevented from leaking to the substrate 1201.

[0249] In some embodiments, the third height H3 ranges from 2 to 4 μm, the fourth height H4 ranges from 3 to 6 μm, the first gap G1 ranges from 0.5 to 2 μm, and the second gap G2 ranges from 0.1 to 0.8 μm.

[0250] In some embodiments, to improve the coupling efficiency between waveguides, the larger the gap between the waveguides, the longer the overlapping length between the waveguides. Thus, the size of the first gap G1 is 1.5 μm, and the length of the first overlapping part is 600 μm; the size of the second gap G2 is 0.78 μm, and the length of the second overlapping part is 300 μm.

[0251] In some embodiments, depending on the position of the optical fiber, no transition waveguide may be provided between the first coupling waveguide 1204 and the second coupling waveguide 1205 , that is, the waveguide coupler 1200 only includes the first coupling waveguide 1204 and the second coupling waveguide 1205 .

[0252] FIG23 is a third transverse cross-sectional view of an end-face coupler in an optical module according to some embodiments of the present disclosure. As shown in FIG23 , along the epitaxial growth direction, the first coupling waveguide 1204 is located above the second coupling waveguide 1205. The second coupling waveguide 1205 may be close to the first cladding 1202. The position of the first coupling waveguide 1204 within the second cladding 1203 corresponds to the transmitting optical fiber and the receiving optical fiber. For example, a third height H3 is defined between the first coupling waveguide 1204 and the side of the substrate 1201 facing the first cladding 1202. A first gap G1 is defined between the first coupling waveguide 1204 and the second coupling waveguide 1205. A larger first gap G1 makes coupling between the first coupling waveguide 1204 and the second coupling waveguide 1205 more difficult. Therefore, the first gap G1 must be within a predetermined range to ensure coupling efficiency between the first coupling waveguide 1204 and the second coupling waveguide 1205 and to reduce leakage of the light field within the second cladding 1203 into the substrate 1201.

[0253] In some embodiments, a third height H3 between the first coupling waveguide 1204 and the substrate 1201 is in a range of 2 to 4 μm, and a first gap G1 between the first coupling waveguide 1204 and the second coupling waveguide 1205 is in a range of 0.1 to 0.8 μm.

[0254] In some embodiments, the refractive index of the first coupling waveguide 1204 is greater than the refractive index of the second cladding 1203, the refractive index of the second coupling waveguide 1205 is greater than the refractive index of the second cladding 1203, and the first gap G1 between the first coupling waveguide 1204 and the second coupling waveguide 1205 is within a preset range, so that the light transmitted by the first coupling waveguide 1204 can be gradually coupled from the first coupling waveguide 124 to the second coupling waveguide 1205, or the light transmitted by the second coupling waveguide 1205 can be gradually coupled from the second coupling waveguide 1205 to the first coupling waveguide 1204.

[0255] In this way, the signal light modulated by the optical chip 400 is coupled to the second coupling waveguide 1205, the second coupling waveguide 1205 couples the signal light to the first coupling waveguide 1204, the first coupling waveguide 1204 couples the signal light to the transmitting optical fiber, and the signal light is transmitted to the optical fiber adapter 700 through the transmitting optical fiber, and then transmitted to the external optical fiber, thereby realizing the emission of light.

[0256] The received light transmitted by the external optical fiber is transmitted to the receiving optical fiber through the optical fiber adapter 700. The received light is coupled to the first coupling waveguide 1204 through the receiving optical fiber. The first coupling waveguide 1204 couples the received light to the second coupling waveguide 1205. The second coupling waveguide 1205 couples the received light to the optical chip 400. The optical chip 400 converts the received optical signal into an electrical signal, thereby realizing light reception.

[0257] In some embodiments, the refractive index of the first cladding 1202 may be a single refractive index, or the refractive index of the first cladding 1202 may be a graded refractive index, that is, along the epitaxial growth direction, the refractive index of the first cladding 1202 gradually decreases, the refractive index of the first cladding 1202 near the lower surface is smaller than the refractive index of the substrate 1201, and the refractive index of the first cladding 1202 near the upper surface is smaller than the refractive index of the second cladding 1203, so as to prevent the light field in the second cladding 1203 from leaking to the substrate 1201.

[0258] Figure 24 is a fourth transverse cross-sectional view of an end-face coupler in an optical module according to some embodiments of the present disclosure, and Figure 25 is a longitudinal cross-sectional view of an end-face coupler in an optical module according to some embodiments of the present disclosure. As shown in Figures 24 and 25, in some embodiments, the waveguide coupler 1200 may further include a third cladding layer 1211. Along the epitaxial growth direction, the first cladding layer 1202 is located on the substrate 1201, the second cladding layer 1203 is located on the first cladding layer 1202, and the third cladding layer 1211 is located on the second cladding layer 1203. The first cladding layer 1202 and the third cladding layer 1211 are symmetrical with respect to the second cladding layer 1203. The refractive index of the third cladding layer 1211 is less than the refractive index of the second cladding layer 1203.

[0259] In some embodiments, the refractive index of the first cladding 1202 is the same as the refractive index of the third cladding 1211 to simulate the refractive index distribution of the optical fiber, which can form better confinement of the light field in the longitudinal direction.

[0260] In some embodiments, the refractive index of the first cladding 1202 is the same as the refractive index of the third cladding 1211, which means that the refractive indices are theoretically the same. As long as the error between the refractive index of the first cladding 1202 and the refractive index of the third cladding 1211 is within a preset error range, the refractive index of the first cladding 1202 can be considered to be the same as the refractive index of the third cladding 1211.

[0261] The function of the first cladding 1202 and the third cladding 1211 is to reflect light leaking from the second cladding 1203 so that the light can only be transmitted within the second cladding 1203. They belong to the same concept and design. If there is a deviation between the refractive index of the first cladding 1202 and the refractive index of the third cladding 1211 due to differences in production and manufacturing or individual differences, the refractive index of the first cladding 1202 and the third cladding 1211 can also be considered to be the same.

[0262] A first coupling waveguide 1204, a first transition waveguide 1206, a second transition waveguide 1207 and a second coupling waveguide 1205 are provided in the second cladding 1203. One end of the first coupling waveguide 1204 is coupled and connected to the optical fiber, the other end of the first coupling waveguide 1204 is coupled and connected to one end of the first transition waveguide 1206, the other end of the first transition waveguide 1206 is coupled and connected to one end of the second transition waveguide 1207, the other end of the second transition waveguide 1207 is coupled and connected to one end of the second coupling waveguide 1205, and the other end of the second coupling waveguide 1205 is optically connected to the optical chip 400, so as to realize optical coupling between the optical fiber and the optical chip 400 through the waveguide coupler 1200.

[0263] Side grooves 1210 are etched on both sides of the waveguide in the second cladding 1203. The refractive index of the medium filled in the side grooves 1210 is lower than that of the second cladding 1203 to simulate the transverse refractive index distribution of the optical fiber. The side grooves thus strengthen the horizontal confinement of the light field in the second cladding 1203.

[0264] When light is transmitted through the first coupling waveguide 1204, the second transition waveguide 1207, the first transition waveguide 1206, and the second coupling waveguide 1205, since the refractive index of the second cladding 1203 is greater than the refractive indices of the first cladding 1202 and the third cladding 1211, the light leaking into the second cladding 1203 will be reflected at the first cladding 1202 and the third cladding 1211. The reflected light can be coupled into the coupling waveguide or the transition waveguide and is unlikely to leak into the substrate 1201, thereby reducing substrate leakage loss and achieving ultra-low coupling insertion loss of standard single-mode optical fiber.

[0265] Of course, in addition to the aforementioned method of placing a coupler assembly between the optical chip and the optical fiber to improve the optical coupling efficiency between the two, the coupler assembly can also be placed at the optical port of the optical chip. For details, please refer to the following examples. In addition, coupler assemblies can also be placed simultaneously on the optical chip and the optical fiber, or at the optical port of the optical chip, to improve the optical coupling efficiency between the optical chip and the optical fiber.

[0266] In some embodiments, the coupler component is an optical coupler.

[0267] 14 , the optical chip 400 is used to modulate and demodulate optical signals: the optical chip 400 modulates the received electrical signal into an optical signal, and the optical chip 400 demodulates the received optical signal into an electrical signal.

[0268] In some embodiments, the optical chip 400 may be a monolithically integrated optical chip. Monolithic integration refers to directly epitaxially growing optical device materials on a single substrate to prepare an optical device with intended functions.

[0269] For example, optical chip 400 can be a monolithically integrated silicon photonic chip. Silicon is easily etched, allowing for the integration of functional devices within the silicon photonic chip, resulting in good integration. For example, a beam splitter, combiner, mixer, photodetector, and the like can be integrated within the silicon photonic chip. As an indirect bandgap semiconductor material, silicon does not exhibit a linear electro-optic effect, only a weak second-order electro-optic effect, resulting in a low modulation rate for the silicon photonic chip.

[0270] By way of example, optical chip 400 can be a monolithically integrated thin-film lithium niobate chip. Thin-film lithium niobate exhibits a linear electro-optic effect. An applied electric field causes a linear change in its refractive index in the corresponding direction, allowing light waves transmitted through the medium to have controllable intensity, phase, and other information. Therefore, thin-film lithium niobate can be used as the material for optical modulators, enabling, for example, high modulation rates. Thin-film lithium niobate is relatively hard and difficult to etch, making it difficult to integrate multiple functional devices on its surface. Furthermore, thin-film lithium niobate chips exhibit low optical loss.

[0271] In some embodiments, optical chip 400 may be a hybrid integrated optical chip. Hybrid integration involves fabricating optical components on different substrates based on the strengths of their respective material systems and manufacturing process characteristics, and then integrating them together. The advantage of hybrid integration is that it can fully leverage the excellent performance of different material systems.

[0272] Exemplarily, optical chip 400 may be a III-V / Si hybrid integrated optical chip. In a III-V / Si hybrid integrated optical chip, the optical modulator is grown using a III-V semiconductor material. III-V is a direct bandgap semiconductor material with a strong quantum well-confined Stark effect. By controlling the change in the applied electric field, carrier changes are induced, thereby causing a change in the refractive index, thereby achieving optical signal modulation. The growth material system for the optical splitter, optical combiner, mixer, optical detector, etc. is Si-based. In some embodiments, the III-V / Si hybrid integrated optical chip may be an InP / Si hybrid integrated optical chip.

[0273] For example, the optical chip 400 may be a thin-film lithium niobate / Si hybrid integrated optical chip. Compared to a III-V / Si hybrid integrated optical chip, the optical modulator in the thin-film lithium niobate / Si hybrid integrated optical chip is a thin-film lithium niobate-based optical modulator.

[0274] In some embodiments, optical chip 400 may be a monolithically integrated silicon photonic chip. Because silicon is an indirect bandgap semiconductor material with extremely low luminous efficiency, a light source 500 is positioned on one side of optical chip 400. Light from light source 500 is emitted from the side and coupled into optical chip 400. The light emitted by light source 500 does not carry data. Upon entering optical chip 400, it is phase-modulated by optical chip 400 to embed an electrical signal into the light, resulting in data-carrying light, i.e., generating an optical transmission signal, thereby enabling optical signal transmission.

[0275] In some embodiments, optical chip 400 may be an InP / Si hybrid integrated optical chip. Group III-V semiconductor materials are direct bandgap semiconductors with strong gain characteristics. Therefore, Group III-V materials have excellent luminescence properties, such as InP lasers. An InP laser is integrated within the InP / Si hybrid integrated optical chip as a light source.

[0276] Figure 26 is a schematic diagram of the internal structure of an optical chip provided according to some embodiments of the present disclosure. As shown in Figure 26, in some embodiments, the optical chip 400 can be a monolithic integrated silicon photonic chip.

[0277] In some embodiments, the light source 500 is disposed outside the optical chip 400. The light generated by the light source 500 and carrying no signal is coupled into the optical chip 400. The light generated by the light source 500 and carrying no signal is split into a first light beam and a second light beam by the optical splitter 410 integrated in the optical chip 400.

[0278] The first light beam is coupled as local oscillator light into the optical demodulator 420 built into the optical chip 400, and the external optical signal is also coupled into the optical demodulator 420. The first light beam and the external optical signal to be demodulated are coherently demodulated in the optical demodulator to demodulate the corresponding electrical signal.

[0279] The second light beam is transmitted to the polarization beam splitter 430 as a light source and is split by the polarization beam splitter 430 into two beams with different polarization directions: TE polarized light and TM polarized light.

[0280] The TE polarized light is split into two beams by the beam splitter 450. These beams are then coupled to the two optical modulators 460 located on the upper side of Figure 26. The upper optical modulator 460 performs I-modulation on the received light to generate an I-modulated signal, while the lower optical modulator 460 performs Q-modulation on the received light to generate a Q-modulated signal. The I-modulated and Q-modulated signals of this beam are then combined in a combiner 470 to generate a first sub-modulated optical signal.

[0281] The TM polarized light is split into two beams by beam splitter 440. These beams are then coupled to the two optical modulators 460 located at the bottom in Figure 26. The upper optical modulator 460 performs I-modulation on the received light, generating an I-modulated signal; the lower optical modulator 460 performs Q-modulation on the received light, generating a Q-modulated signal. The I-modulated and Q-modulated signals of this beam are then combined in a combiner 480 to generate a second sub-modulated optical signal.

[0282] The first sub-modulated optical signal and the second sub-modulated optical signal are respectively connected to the combiner 490 to be combined to generate an optical modulated signal, thereby achieving signal modulation.

[0283] In some embodiments, the optical port of the optical chip 400 includes an output optical port, a first input optical port, and a second input optical port. The output optical port of the optical chip 400 is optically connected to the combiner 490 , the first input optical port is optically connected to the optical splitter 410 , and the second input optical port is optically connected to the optical demodulator 420 .

[0284] The output optical port of the optical chip 400 is used to output the optical transmit signal modulated by the optical chip 400. The first input optical port is used to input the light generated by the light source 500 without carrying data into the optical chip 400, and the second input optical port is used to input the optical signal to be demodulated from the outside into the optical chip 400.

[0285] In some embodiments, an optical fiber array 700 is disposed outside the optical chip 400 , and includes a first optical fiber ribbon 710 , a second optical fiber ribbon 720 , and a third optical fiber ribbon 730 .

[0286] In some embodiments, the first optical fiber ribbon 710 is coupled to the optical output port of the optical chip 400. The optical transmit signal modulated and generated by the optical chip 400 is output from the optical chip 400 through the optical output port, coupled into the first optical fiber ribbon 710, and then output to the outside of the optical module through the first optical fiber ribbon 710.

[0287] In some embodiments, the second optical fiber ribbon 720 is coupled to the first optical input port of the optical chip 400. Light generated by the light source 500 that does not carry data is transmitted through the second optical fiber ribbon 720 to the first optical input port of the optical chip 400. The light is then coupled into the optical chip 400 and into the optical splitter 410 for subsequent optical signal modulation.

[0288] In some embodiments, the third optical fiber ribbon 730 is coupled to the second optical input port of the optical chip 400. An external optical signal to be demodulated is transmitted through the third optical fiber ribbon 730 to the second optical input port of the optical chip 400, where it is then coupled into the optical chip 400 and then into the optical demodulator 420 for demodulation.

[0289] In some embodiments, the optical transmit signal modulated by the optical chip 400 is transmitted to the first optical fiber ribbon 710 via a waveguide within the optical chip 400. The light source input to the optical chip 400 by the second optical fiber ribbon 720 is transmitted to the optical splitter 410 via a waveguide within the optical chip 400. The optical signal to be demodulated input to the optical chip 400 by the third optical fiber ribbon 730 is transmitted to the optical demodulator 420 via a waveguide within the optical chip.

[0290] In some embodiments, the waveguide within the optical chip 400 utilizes a silicon-on-insulator (SOI) waveguide. The SOI waveguide comprises, from bottom to top, a substrate, a buried oxide layer (box), and a top silicon layer. Exemplarily, the buried oxide layer is a SiO2 layer.

[0291] A large refractive index difference between the top silicon layer and the buried oxide layer creates a strong confinement effect on the light beam, resulting in a smaller effective mode field area. When the refractive index contrast of the SOI waveguide is greater than that of the optical fiber, the effective mode field area of ​​the SOI waveguide is smaller than that of the optical fiber. Consequently, there is a mode mismatch between the SOI waveguide and the optical fiber, resulting in large coupling losses when the two are coupled, thus reducing the coupling efficiency.

[0292] For example, the effective area of ​​a silicon waveguide mode field is typically less than 1 μm 2 , while the effective area of ​​the optical field of a standard single-mode fiber is typically 70 μm 2 about.

[0293] In some embodiments of the present disclosure, end-face coupling is employed between the optical chip 400 and the optical fiber. An optical coupler 800 is provided at the optical port of the optical chip 400. Optical coupler 800 is an end-face coupler. It bridges the optical field energy transmission between the SOI waveguide and the optical fiber, improving the optical coupling efficiency between the two.

[0294] In some embodiments, optical couplers 800 are respectively provided at the optical output port, the first optical input port, and the second optical input port of the optical chip 400 .

[0295] In some embodiments, an optical coupler 800 is located between the combiner 490 and the first optical fiber ribbon 710 to improve the optical coupling efficiency between the SOI waveguide inside the optical chip 400 and the first optical fiber ribbon 710 .

[0296] In some embodiments, another optical coupler 800 is located between the optical splitter 410 and the second optical fiber ribbon 720 to improve the optical coupling efficiency between the SOI waveguide inside the optical chip 400 and the second optical fiber ribbon 720 .

[0297] In some embodiments, another optical coupler 800 is located between the optical demodulator 420 and the third optical fiber ribbon 730 to improve the optical coupling efficiency between the SOI waveguide inside the optical chip 400 and the third optical fiber ribbon 730 .

[0298] Figure 27 is a first perspective structural diagram of an optical coupler provided according to some embodiments of the present disclosure. As shown in Figure 27 , in some embodiments, optical coupler 800 is configured to improve the optical coupling efficiency between an SOI waveguide and an optical fiber. Optical coupler 800 includes a substrate 810 and a buried oxide layer 820. Exemplarily, substrate 810 is a silicon-based substrate.

[0299] In some embodiments, the buried oxide layer 820 is a SiO 2 layer. The buried oxide layer 820 is located above the substrate 810 and has a thickness less than that of the substrate 810.

[0300] In some embodiments, the transmission waveguide 830 is disposed above the buried oxide layer 820. The top silicon layer of the SOI wafer is photolithographically etched to obtain the transmission waveguide 830. Exemplarily, the transmission waveguide 830 is a silicon waveguide.

[0301] In some embodiments, a buried oxide layer 820 is located between the substrate 810 and the transmission waveguide 830. The refractive index of the buried oxide layer 820 is smaller than that of the transmission waveguide 830. Due to the large difference in refractive indices between the buried oxide layer 820 and the transmission waveguide 830, the transmission waveguide 830 has a strong confining effect on the light field, and the light field is primarily confined within the transmission waveguide 830 for transmission, thereby reducing transmission loss.

[0302] In some embodiments, to improve the optical coupling efficiency between the optical chip 400 and the optical fiber ribbon, a coupling waveguide array 850 is provided at the edge of the optical coupler 800. The coupling waveguide array 850 is located at the end of the optical coupler 800 facing the optical port of the optical fiber chip 400 to achieve optical coupling with the optical fiber array. The coupling waveguide array 850 is located at the optical port of the optical coupler 800.

[0303] In some embodiments, a transition waveguide 840 is formed above the transmission waveguide 830. One end of the transition waveguide 840 faces the coupling waveguide array 850 to be optically coupled with the coupling waveguide array 850, and the other end faces the transmission waveguide 830 to be optically coupled with the transmission waveguide 830.

[0304] In some embodiments, both the coupled waveguide array 850 and the transition waveguide 840 can be silicon nitride waveguides. Silicon nitride has a transparent window and low temperature sensitivity in the optical communication band, and its process is highly compatible with CMOS. The refractive index of silicon nitride is approximately 1.98, while that of silicon waveguides is approximately 3.4, and that of SiO2 is approximately 1.44. Therefore, silicon nitride's ability to confine the optical field is between that of silicon waveguides and SiO2 waveguides, making it a suitable material for end-face coupler designs based on high-refractive-index, small-cross-sectional waveguides.

[0305] In some embodiments, when the coupling waveguide array 850 and the transition waveguide 840 are silicon nitride waveguides, the coupling waveguide array 850 and the transition waveguide 840 have the same refractive index. The refractive index of the transition waveguide 840 is smaller than the refractive index of the substrate 810, and the refractive index of the transition waveguide 840 is smaller than the refractive index of the transmission waveguide 830.

[0306] In some embodiments, the coupling waveguide array 850 can be arranged in different combinations at one end of the transition waveguide 840. The coupling waveguide array 850 is located at one end of the transition waveguide 840 facing the optical fiber array 700.

[0307] In some embodiments, coupling waveguide array 850 includes at least two coupling waveguides. The coupling waveguides are symmetrically arranged about the central axis of transition waveguide 840. FIG27 shows coupling waveguide array 850 including two coupling waveguides: coupling waveguide 851 and coupling waveguide 852. Coupling waveguide 851 and coupling waveguide 852 are located on either side of transition waveguide 840.

[0308] Since the refractive index of the coupling waveguide 851 and the coupling waveguide 852 is greater than the refractive index of SiO2, and the coupling waveguide 851 and the coupling waveguide 852 are respectively located on both sides of the transition waveguide 840, this can form a better constraint on the light field in the horizontal direction, confining the light field within the transition waveguide 840, thereby increasing the optical coupling efficiency.

[0309] In some embodiments, the coupling waveguide 851 and the coupling waveguide 852 are thinner strip waveguides, or tapered waveguides.

[0310] In some embodiments, a first gradient region 841 is formed at one end of the transition waveguide 840 facing the coupling waveguide array 850, and a second gradient region 842 is formed at one end of the transition waveguide 840 facing the transmission waveguide 830. A flat region 843 is formed between the first gradient region 841 and the second gradient region 842.

[0311] The waveguide widths of the first gradient region 841 and the second gradient region 842 present opposite gradient shapes.

[0312] In some embodiments, a third gradual change region 831 is formed at one end of the transmission waveguide 830 toward the transition waveguide 830. The waveguide widths of the third gradual change region 831 and the second gradual change region 842 also present opposite gradual changes.

[0313] In some embodiments, along the direction of the coupling waveguide array 850 pointing to the transmission waveguide 830, the waveguide width of the first gradient zone 841 gradually increases, the waveguide width of the second gradient zone 842 gradually decreases, and the waveguide width of the third gradient zone 831 gradually increases.

[0314] In some embodiments, when the second optical fiber ribbon 720 and the third optical fiber ribbon 730 transmit the non-data-carrying light output by the light source 500 and the external optical signal to be demodulated, respectively, to the optical chip, the waveguide width of the first gradient region 841 gradually increases along the direction of light field transmission. This causes more light field to be squeezed from the coupling waveguides 851 and 852 into the first gradient region 841 of the transition waveguide 840. The light field continues along the first gradient region 841 to the flat region 843, where it maintains its energy, and then continues to move to the second gradient region 842. The waveguide width of the second gradient region 842 gradually decreases, while the waveguide width of the third gradient region 831 gradually increases. This causes more light field to be squeezed from the second gradient region 842 of the transition waveguide 840 into the transmission waveguide 830. The light field is then connected along the transmission waveguide 830 to the optical splitter 410 or optical demodulator 420 for modulation or demodulation of the optical signal.

[0315] In some embodiments, the optical transmit signal modulated and generated by the optical chip 400 is output via the combiner 490 and transmitted along the transmission waveguide 830. Along the direction of light field transmission, the waveguide width of the third gradient region 831 gradually decreases, while the waveguide width of the second gradient region 842 gradually increases. This allows more light field to be squeezed from the transmission waveguide 830 into the second gradient region 842 of the transition waveguide 840. The light field then moves to the flat region 843, where it maintains its light field strength, and continues to move into the first gradient region 841. Along the direction of light field transmission, the waveguide width of the first gradient region 841 gradually decreases, causing the light field to be squeezed into the coupling waveguide array 850 and then connected to the first optical fiber ribbon 710 along the coupling waveguide array 850 to transmit the optical transmit signal to the outside.

[0316] Among them, as the waveguide width of the first gradient zone 841 gradually decreases, the limiting effect of the waveguide on light gradually weakens, and a light field with a larger cross-section is formed at the end of the first gradient zone 841 to adapt to the light field area of ​​the first optical fiber ribbon 710. It can then be directly coupled with the first optical fiber ribbon 710, and the optical coupling efficiency between the two increases accordingly.

[0317] In some embodiments, the hybrid waveguide system composed of the coupling waveguide array 850 and the transition waveguide 840 can achieve efficient coupling with the optical fiber ribbon.

[0318] In some embodiments, when the second optical fiber ribbon 720 and the third optical fiber ribbon 730 transmit the light without data output by the light source 500 and the optical signal to be demodulated from the outside to the optical chip 400 respectively, the light field is gradually coupled into the transition waveguide 840 along the hybrid waveguide system composed of the coupling waveguide array 850 and the transition waveguide 840. As the light field is transmitted, it is gradually coupled into the transmission waveguide 830, and thus transmitted inside the optical chip 400 through the transmission waveguide 830.

[0319] In some embodiments, the optical emission signal generated by the modulation of the optical signal 400 is transmitted along the transmission waveguide 830 inside the optical chip 400. As the optical field is transmitted, it is gradually coupled into the transition waveguide 840, and then coupled into the hybrid waveguide system composed of the coupling waveguide array 850 and the transition waveguide 840, until it is coupled into the first optical fiber ribbon 710, and the optical emission signal is transmitted to the outside of the optical module along the first optical fiber ribbon 710.

[0320] In some embodiments, the transition waveguide 840 and the transmission waveguide 830 are disposed adjacent to each other in the longitudinal direction to improve coupling efficiency therebetween. For example, the longitudinal gap between the transition waveguide 840 and the transmission waveguide 830 is relatively small.

[0321] In some embodiments, the transmission waveguide 830 is separated from the substrate 810 by a buried oxide layer 820. When the buried oxide layer 820 is thin, the transmission waveguide 830 is closer to the substrate 810. Since the transition waveguide 840 is closer to the transmission waveguide 830, the transition waveguide 840 is also closer to the substrate 810.

[0322] In some embodiments, the coupling waveguide array 850 and the transition waveguide 840 have the same refractive index. For example, both are silicon nitride waveguides. When the transition waveguide 840 is close to the substrate 810 and its refractive index is lower than that of the substrate 810, the light field may leak toward the substrate 810 when the hybrid waveguide system composed of the coupling waveguide array 850 and the transition waveguide 840 couples with the transition waveguide 840.

[0323] In some embodiments, when the transmission waveguide 830 and the transition waveguide 840 are relatively close to the substrate, when the light field is coupled between the transition waveguide 840 and the transmission waveguide 830, less light field leaks toward the substrate 810 because the refractive index of the transition waveguide 840 is smaller than that of the transmission waveguide 830. It is understood that when the thickness of the buried oxide layer 820 is further reduced, the light field will also leak toward the substrate 810 when coupled between the transition waveguide 840 and the transmission waveguide 830.

[0324] In some embodiments, an SOI waveguide is prepared using an SOI silicon wafer. For example, the silicon on the top surface of the SOI silicon wafer is photoetched to form a transmission waveguide 830. For example, the surface etching performance of a 12-inch SOI silicon wafer is better than that of an 8-inch SOI silicon wafer. The buried oxide layer thickness of the 12-inch SOI silicon wafer is 2 μm, and the buried oxide layer thickness of the 8-inch SOI silicon wafer is 3 μm. When using a 12-inch SOI silicon wafer, the buried oxide layer thickness of 2 μm will cause the light field to leak more easily toward the substrate 810 when the above-mentioned hybrid waveguide system is coupled with the transition waveguide 840.

[0325] In some embodiments, a high refractive index region 860 is formed above the buried oxide layer 820. The high refractive index region 860 wraps the transmission waveguide 830, the coupling waveguide array 850, and the transition waveguide 840. Exemplarily, the substrate 810, the buried oxide layer 820, and the high refractive index region 860 are stacked from bottom to top.

[0326] In some embodiments, the high refractive index region 860 includes a region having a refractive index greater than the refractive index of the buried oxide layer 820. Illustratively, the refractive index of the buried oxide layer 820 is fixed.

[0327] Based on the characteristic that the light field tends to be transmitted toward the region with a high refractive index, the high refractive index region 860 is located above the buried oxide layer 820, and the high refractive index region 860 includes a region with a refractive index greater than that of the buried oxide layer 820. Then, under the effect of the refractive index difference between the high refractive index region 860 and the buried oxide layer 820, the light field inside the optical chip gradually shifts upward, the light field is lifted upward, and the distance between the light field and the substrate 810 is increased, thereby reducing the light field leakage toward the substrate 810 and improving the optical coupling efficiency.

[0328] In some embodiments, the high refractive index region 860 shown in FIG27 is a region of uniform refractive index. In this case, the refractive index of the entire high refractive index region 860 is greater than the refractive index of the buried oxide layer 820. The transmission waveguide 830, the transition waveguide 840, and the coupling waveguide array 850 are enclosed in the high refractive index region 860.

[0329] In some embodiments, buried oxide layer 820 is a SiO2 layer. High refractive index region 860 is a SiO2 region. The refractive index of the SiO2 medium in high refractive index region 860 is greater than the refractive index of the SiO2 medium in buried oxide layer 820. When SiO2 media with different refractive indices are stacked together, the difference in refractive index between the two can better confine the light field in the longitudinal direction, directing the light field away from substrate 810, thereby reducing light leakage loss toward substrate 810.

[0330] In some embodiments, the refractive index of the SiO 2 medium may be varied by changing the deposition rate, gas ratio, gas flow rate, etc. during the SiO 2 preparation process.

[0331] Figure 28 is a cross-sectional structural diagram of an optical coupler according to some embodiments of the present disclosure. As shown in Figure 28 , in some embodiments, a substrate 810, a buried oxide layer 820, and a high refractive index region 860 are stacked in sequence. Transmission waveguides 830, transition waveguides 840, and a coupling waveguide array 850 are encapsulated within the high refractive index region 860.

[0332] In some embodiments, the high refractive index region 860 is a region with a uniform refractive index, and the refractive index of the high refractive index region 860 is greater than the refractive index of the buried oxide layer 820, thereby better constraining the light field in the longitudinal direction, lifting the light field upward, and moving the light field away from the substrate 810, thereby reducing light leakage loss to the substrate 810.

[0333] In some embodiments, the total thickness of high refractive index region 860 is limited by the optical field effective area of ​​the optical fiber. The thickness of high refractive index region 860 determines the maximum optical field size of optical coupler 800. Therefore, the thickness of high refractive index region 860 is predetermined to ensure that the optical field effective area between transmission waveguide 830 and optical fiber array 700 is compatible.

[0334] In some embodiments, coupling waveguide array 850 includes coupling waveguides 851 and 853. Coupling waveguides 851 and 853 are longitudinally arranged and both located on one side of transition waveguide 840. Coupling waveguides symmetrically arranged with respect to coupling waveguides 851 and 853 are provided on the other side of transition waveguide 840.

[0335] In some embodiments, there is no limitation on the relative positional relationship between the coupling waveguide 851, the coupling waveguide 853, and the transition waveguide 840. For example, the coupling waveguide 851 and the coupling waveguide 853 may both be located above the transition waveguide 840. For example, the coupling waveguide 851 and the coupling waveguide 853 may be located above and below the transition waveguide 840, respectively.

[0336] Figure 29 is a second perspective view of the structure of an optical coupler according to some embodiments of the present disclosure. As shown in Figure 29 , in some embodiments, a substrate 810, a buried oxide layer 820, and a high refractive index region 860 are stacked in sequence. Transmission waveguides 830, transition waveguides 840, and a coupling waveguide array 850 are encapsulated within the high refractive index region 860.

[0337] In some embodiments, the high refractive index region 860 includes a plurality of layers having different refractive indices, and at least one layer has a refractive index greater than that of the buried oxide layer 820 .

[0338] In some embodiments, layers with different refractive indices are stacked to form the high refractive index region 860 , and at least one layer in the high refractive index region 860 has a refractive index greater than that of the buried oxide layer 820 .

[0339] In some embodiments, taking the high refractive index region 860 including four layers with different refractive indices as an example, the high refractive index region 860 includes a first refractive index layer 861 , a second refractive index layer 862 , a third refractive index layer 863 and a fourth refractive index layer 864 .

[0340] The first refractive index layer 861 , the second refractive index layer 862 , the third refractive index layer 863 and the fourth refractive index layer 864 are stacked in sequence from bottom to top.

[0341] In some embodiments, the first refractive index layer 861 , the second refractive index layer 862 , the third refractive index layer 863 , and the fourth refractive index layer 864 have different refractive indices.

[0342] For example, the first refractive index layer 861, the second refractive index layer 862, the third refractive index layer 863, and the fourth refractive index layer 864 are each SiO2 layers having different refractive indices, i.e., the medium of each layer is SiO2. As described above, the refractive index of SiO2 can be varied by changing the deposition rate, gas ratio, gas flow rate, etc. during the SiO2 preparation process.

[0343] Exemplarily, the medium of the first refractive index layer 861, the second refractive index layer 862, the third refractive index layer 863 and the fourth refractive index layer 864 can be SiO2 or non-SiO2, as long as the refractive index of the medium meets the requirements: there is at least one layer of medium with a refractive index greater than the refractive index of the buried oxide layer 820.

[0344] In some embodiments, at least one of the first refractive index layer 861, the second refractive index layer 862, the third refractive index layer 863, and the fourth refractive index layer 864 has a refractive index greater than that of the buried oxide layer 820, so as to lift the light field upward and away from the substrate 810, thereby reducing light field leakage to the substrate 810.

[0345] Illustratively, the refractive index of the first refractive index layer 861 is greater than that of the buried oxide layer 820 . The refractive indices of the second refractive index layer 862 , the third refractive index layer 863 , and the fourth refractive index layer 864 may be greater than or less than that of the buried oxide layer 820 .

[0346] For example, the refractive index of the third refractive index layer 863 is greater than that of the buried oxide layer 820 . The refractive indexes of the first refractive index layer 861 , the second refractive index layer 862 , and the fourth refractive index layer 864 may be greater than or less than that of the buried oxide layer 820 .

[0347] Figure 30 is a second cross-sectional structural diagram of an optical coupler according to some embodiments of the present disclosure. As shown in Figure 30 , in some embodiments, a substrate 810, a buried oxide layer 820, a first refractive index layer 861, a second refractive index layer 862, a third refractive index layer 863, and a fourth refractive index layer 864 are stacked sequentially from bottom to top.

[0348] In some embodiments, taking the example of the refractive index of the third refractive index layer 863 being greater than the refractive index of the buried oxide layer 820, the refractive index of the third refractive index layer 863 is greater than the refractive index of the buried oxide layer 820, so as to lift the light field upward, so that the light field is away from the substrate 810, thereby reducing the leakage of the light field to the substrate 810.

[0349] In some embodiments, the total thickness of the high refractive index region 860 is limited by the optical field effective area of ​​the optical fiber. The high refractive index region 860 has a predetermined thickness to adapt the optical field effective area between the transmission waveguide 830 and the optical fiber array 700.

[0350] In some embodiments, taking the case where the refractive index of the third refractive index layer 863 is greater than the refractive index of the buried oxide layer 820 as an example, the thickness of the third refractive index layer 863 with the highest refractive index determines the maximum light field size of the optical coupler 800. In order to efficiently couple with the optical fiber, the thickness of the third refractive index layer 863 should be as large as possible. Therefore, in a balanced design, the number of layers with different refractive indices should not be too many to avoid the thickness of the third refractive index layer 863 being too small.

[0351] In some embodiments, taking the example that the refractive index of the third refractive index layer 863 is greater than the refractive index of the buried oxide layer 820 , the thickness of the third refractive index layer 863 is greater than the thicknesses of the first refractive index layer 861 , the second refractive index layer 862 , and the fourth refractive index layer 864 .

[0352] Figure 31 illustrates an assembly diagram of a transmission waveguide and a transition waveguide according to some embodiments of the present disclosure. As shown in Figure 31 , in some embodiments, a first gradual transition region 841 is formed on the end of the transition waveguide 840 facing the coupling waveguide array 850, and a second gradual transition region 842 is formed on the end of the transition waveguide 840 facing the transmission waveguide 830. A flat region 843 is formed between the first gradual transition region 841 and the second gradual transition region 842.

[0353] The waveguide widths of the first gradient region 841 and the second gradient region 842 present opposite gradient shapes.

[0354] In some embodiments, a third gradual change region 831 is formed at one end of the transmission waveguide 830 toward the transition waveguide 830. The waveguide widths of the third gradual change region 831 and the second gradual change region 842 also present opposite gradual changes.

[0355] Along the light field transmission direction, the first gradient region 841 and the third gradient region 831 have opposite gradient trends, which is beneficial to the coupling of light between the transition waveguide 840 and the transmission waveguide 830 and improves the coupling efficiency.

[0356] FIG32 is a diagram illustrating an assembly of a transition waveguide and a coupled waveguide array according to some embodiments of the present disclosure. As shown in FIG32 , in some embodiments, the coupled waveguide array 850 is located at the end where the first gradient region 841 is located.

[0357] In some embodiments, the coupling waveguide array 850 includes a coupling waveguide 851, a coupling waveguide 852, and a coupling waveguide 854. The coupling waveguide 854 is located above the first gradient region 841, and the coupling waveguides 851 and 852 are located on either side of the first gradient region 841. The coupling waveguides 851 and 852 are symmetrically arranged with respect to the central axis of the first gradient region 841.

[0358] In some embodiments, the coupling waveguide array 850 is enclosed in a high refractive index region 860. The maximum refractive index region in the high refractive index region 860 is still lower than the refractive index of the coupling waveguide array 850. Therefore, when the coupling waveguides 851 and 852 are located on both sides of the first gradient region 841, they can better constrain the light field in the horizontal direction.

[0359] Based on the optical coupler provided in the above embodiment, the present disclosure provides a method for preparing an optical coupler, which is used to prepare the optical coupler. The method for preparing the optical coupler includes:

[0360] S110: etching the top silicon layer on the surface of the SOI wafer to form a transmission waveguide, wherein the SOI wafer includes a substrate, a buried oxide layer and a top silicon layer from bottom to top.

[0361] In some embodiments, the transmission waveguide 830 is obtained by etching the top silicon layer of the SOI wafer by photolithography.

[0362] S120: forming a transition waveguide 840 above one end of the transmission waveguide.

[0363] In some embodiments, in order to improve the coupling efficiency between the transmission waveguide 830 and the transition waveguide 840 , the gap between them in the longitudinal direction is relatively small.

[0364] S130: forming a coupled waveguide array at one end of the transition waveguide.

[0365] In some embodiments, the coupling waveguide array 850 is located at the edge of the optical coupler.

[0366] S140: epitaxially growing a high refractive index region with a uniform refractive index and a refractive index greater than that of the buried oxide layer upwardly along the buried oxide layer; or epitaxially growing layers with different refractive indices upwardly along the buried oxide layer, wherein the refractive index of one layer is greater than that of the buried oxide layer.

[0367] In some embodiments, the transmission waveguide 830 is separated from the substrate 810 by a buried oxide layer 820. When the buried oxide layer 820 is thin, the transmission waveguide 830 is closer to the substrate 810. Since the transition waveguide 840 is closer to the transmission waveguide 830, the transition waveguide 840 is also closer to the substrate 810.

[0368] In some embodiments, the coupling waveguide array 850 and the transition waveguide 840 have the same refractive index. For example, both are silicon nitride waveguides. When the transition waveguide 840 is close to the substrate 810 and its refractive index is lower than that of the substrate 810, the light field may leak toward the substrate 810 when the hybrid waveguide system composed of the coupling waveguide array 850 and the transition waveguide 840 couples with the transition waveguide 840.

[0369] In some embodiments, the high refractive index region 860 includes a region having a refractive index greater than that of the buried oxide layer 820. Under the effect of the refractive index difference between the high refractive index region 860 and the buried oxide layer 820, the light field inside the optical chip gradually shifts upward, and the light field is lifted upward, increasing the distance from the substrate 810, thereby reducing the leakage of the light field toward the substrate 810 and improving the optical coupling efficiency.

[0370] In the optical coupler provided by the present disclosure, the substrate, the buried oxide layer, and the high refractive index region are stacked in sequence. The high refractive index region wraps the transmission waveguide, the coupling waveguide array, and the transition waveguide. The high refractive index region includes a region with a refractive index greater than the refractive index of the buried oxide layer. Exemplarily, when the high refractive index region is a region with a uniform refractive index, the refractive index of the high refractive index region is greater than the refractive index of the buried oxide layer; or, when the high refractive index region includes multiple layers with different refractive indices, at least one layer has a refractive index greater than the refractive index of the buried oxide layer. Based on the characteristic that the light field tends to be transmitted toward the region with a high refractive index, the high refractive index region is located above the buried oxide layer, and the high refractive index region includes a region with a refractive index greater than the refractive index of the buried oxide layer. Then, under the effect of the refractive index difference between the high refractive index region and the buried oxide layer, the light field inside the optical chip gradually shifts upward, and the light field is lifted upward, increasing the distance between the light field and the substrate, thereby reducing the leakage of the light field toward the substrate and improving the light coupling efficiency.

[0371] The polarization beam splitter in the above embodiment may be a polarization rotation beam splitter to achieve deflection and splitting of the polarization multiplexed light beam. The specific structure of the polarization rotation beam splitter may be understood with reference to the following content.

[0372] As shown in FIG14 , in some embodiments, a light source 500 is disposed on the side of the optical chip 400 . Light from the light source 500 is emitted from the side and coupled into the optical chip 400 . The light source 500 serves as an external light source for the optical chip 400 , and the light emitted by the light source 500 enters the optical chip 400 . The light source 500 can optionally be a laser box, which houses a laser. The laser generates a laser beam, and the light source 500 is used to transmit laser light to the optical chip 400 . Lasers, due to their excellent single-wavelength characteristics and wavelength tuning properties, are the preferred light source for optical modules and even optical fiber 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 specific optical communication systems, their light source characteristics and chip components differ significantly from those of lasers. 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 consider these two types of optical modules to be technically instructive for each other.

[0373] The light emitted by the light source 500 is light that does not carry data and enters the optical chip 400. The optical chip 400 performs phase modulation on it to load the electrical signal into the light to obtain light that carries data, that is, to generate an optical transmission signal, thereby realizing the transmission of the optical signal.

[0374] In some embodiments, the optical chip 400 may be a silicon photonic chip, i.e., the optical chip 400 is formed by packaging silicon materials. The silicon photonic chip includes a Mach-Zehnder modulator (MZM), which integrates a silicon photonic phase modulator (SiPM) for modulating and demodulating optical signals.

[0375] In some embodiments, the optical chip 400 may be a thin-film lithium niobate chip, i.e., the optical chip 400 is encapsulated using thin-film lithium niobate material. Thin-film lithium niobate exhibits properties such as the linear electro-optic effect. An applied electric field causes a linear change in its refractive index in the corresponding direction, resulting in light waves propagating through the medium with controllable intensity, phase, and other information. Therefore, thin-film lithium niobate can be used as the material for optical modulators, thereby achieving higher modulation efficiency.

[0376] In some embodiments, optical chip 400 can be a hybrid InP / Si optical chip, i.e., a hybrid InP / Si optical chip is formed by combining InP and Si materials. This hybrid InP / Si optical chip combines the performance of InP and Si materials, resulting in superior performance and increased bandwidth for optical chip 400.

[0377] FIG33 is a schematic diagram of the structure of an optical chip provided according to some embodiments of the present disclosure. As shown in FIG33 , an optical chip 400 is provided with a light inlet 410 on one side, and a polarization rotation beam splitter 700 is disposed within the light inlet 410. A polarization-multiplexed light beam is coupled to the polarization rotation beam splitter 700 through the light inlet 410. The polarization rotation beam splitter 700 splits the polarization-multiplexed light beam and transmits it to the optical chip 400. For example, the polarization-multiplexed light beam includes TM0 polarized light and TE0 polarized light, and the polarization rotation beam splitter 700 splits the polarization-multiplexed light beam into two beams of TE0 polarized light.

[0378] In some embodiments, the optical chip 400 may have one or more light entrances 410 , such as two, three, or four.

[0379] In some embodiments, a light outlet 420 is provided on the other side of the optical chip 400, and a polarization rotation beam splitter 700 may be disposed within the light outlet 420. Exemplarily, the polarization rotation beam splitter 700 disposed within the light outlet 420 is oriented in the opposite direction to the polarization rotation beam splitter 700 disposed within the light inlet 410, such that the polarization rotation beam splitter 700 within the light outlet 420 is used for polarization multiplexing of light beams, thereby polarization-multiplexing two polarized light beams into a single polarized light beam. For example, two TE0 polarized light beams may be polarization-multiplexed into a single light beam comprising TM0 polarized light and TE0 polarized light.

[0380] In some embodiments, the optical chip 400 may have one or more light outlets 420 , such as two, three, or four.

[0381] In some embodiments, the light inlet 410 and the light outlet 420 may be disposed on the same side or adjacent sides of the optical chip 400 .

[0382] In some embodiments, the light inlet 410 is coupled to the light source 500 or to an optical fiber external to the optical module. When the light inlet 410 is coupled to the light source 500, the polarization rotation beam splitter 700 within the light inlet 410 splits the light beam that does not carry a signal. When the light inlet 410 is coupled to an optical fiber external to the optical module, the polarization rotation beam splitter 700 within the light inlet 410 splits the light beam that carries a signal.

[0383] In some embodiments, the light outlet 420 is used to output the optical signal modulated by the optical chip 400 , and the polarization rotation beam splitter 700 of the light outlet 420 is used to output the light beam carrying the signal.

[0384] Figure 34 is a schematic diagram of the structure of a polarization rotation beam splitter according to some embodiments of the present disclosure. Figure 35 is a cross-sectional view taken along the AA direction in Figure 34. Figures 34 and 35 illustrate the structure of a polarization rotation beam splitter. The polarization rotation beam splitter provided in embodiments of the present disclosure is not limited to the structures shown in Figures 34 and 35. The polarization rotation beam splitter 700 provided in embodiments of the present disclosure is described in detail below in conjunction with Figures 34, 35, and other figures.

[0385] In some embodiments, the polarization rotation beam splitter 700 includes a mode conversion portion 710 , wherein the mode conversion portion 710 is formed with a tapered waveguide structure, and the mode conversion portion 710 is configured to convert TM0 polarized light into TE1 polarized light.

[0386] In some embodiments, the mode conversion portion 710 includes a first waveguide 711 and a second waveguide 712. The first waveguide 711 is disposed below the second waveguide 712, and the bottom of the second waveguide 712 is connected to the first waveguide 711. The thickness of the second waveguide 712 is greater than the thickness of the first waveguide 711. Exemplarily, the first waveguide 711 and the second waveguide 712 form an irregular ridge waveguide structure.

[0387] A polarization-multiplexed beam including TM0 polarized light and TE0 polarized light is coupled from one end of the mode conversion section 710 to the mode conversion section 710. Exemplarily, one end of the second waveguide 712 is the coupling end of the polarization-multiplexed beam, i.e., the polarization-multiplexed beam is input from one end of the second waveguide 712. During transmission, the polarization-multiplexed beam is gradually coupled from the second waveguide 712 to the first waveguide 711, and the TM0 polarized light undergoes mode hybridization during propagation and is converted into TE1 polarized light.

[0388] Figure 36 is a partially enlarged view of a polarization rotation beam splitter according to some embodiments of the present disclosure. As shown in Figure 36 , in some embodiments, the second waveguide 712 is located at the top center of the first waveguide 711. Of course, the present disclosure is not limited to placing the second waveguide 712 at the top center of the first waveguide 711. Of course, the present disclosure is not limited to placing the second waveguide 712 above the first waveguide 711; it can also be placed below the first waveguide 711.

[0389] In some embodiments, the width of one end of the first waveguide 711 is smaller than the width of the other end of the first waveguide 711. Exemplarily, the first waveguide 711 is a tapered waveguide.

[0390] In some embodiments, the width of one end of the second waveguide 712 is greater than the width of the other end of the second waveguide 712. Exemplarily, the second waveguide 712 is a tapered waveguide.

[0391] In some embodiments, the width of one end of the second waveguide 712 is greater than or equal to the width of one end of the first waveguide 711 , and the width of the second waveguide 712 is less than the width of the other end of the first waveguide 711 .

[0392] In some embodiments, the width of one end of the first waveguide 711 is greater than or equal to 0.7 μm, and the width of the other end of the first waveguide 711 is less than or equal to 2 μm. For example, the first waveguide 711 is 0.8 μm, and the width of the other end of the first waveguide 711 is 2 μm.

[0393] In some embodiments, the width of the second waveguide 712 at one end is less than or equal to 0.7 μm, and the width at the other end is less than or equal to 0.1 μm. For example, the width of the second waveguide 712 at one end is 0.7 μm, and the width at the other end is 0.05 μm.

[0394] In some embodiments, the polarization rotation beam splitter 700 includes a connecting portion 720 . One end of the connecting portion 720 is connected to the other end of the mode conversion portion 710 . The connecting portion 720 is used to connect the other end of the mode conversion portion 710 . Exemplarily, one end of the connecting portion 720 is connected to the other end of the first waveguide 711 .

[0395] In some embodiments, the width of one end of the connecting portion 720 is greater than the width of the other end of the connecting portion 720. Exemplarily, the connecting portion 720 is a tapered waveguide.

[0396] Figure 37 is a second partially enlarged view of a polarization-rotating beam splitter provided according to some embodiments of the present disclosure. As shown in Figure 37 , in some embodiments, the connecting portion 720 includes a tapered waveguide 721 and a straight waveguide 722. One end of the tapered waveguide 721 is connected to the other end of the first waveguide 711, and the other end of the tapered waveguide 721 is connected to one end of the straight waveguide 722. The width of one end of the tapered waveguide 721 is greater than the width of the other end of the tapered waveguide 721. The tapered waveguide 721 is configured to adjust the width of the connecting portion. The straight waveguide 722 is disposed within the connecting portion 720 to reduce back coupling of the light beam from the other end of the tapered waveguide 721 into the tapered waveguide 721.

[0397] In some embodiments, the polarization rotation beam splitter 700 includes a mode coupling section 730 , which utilizes a mode coupling effect to split the TE1 polarized light and the TE0 polarized light and convert the TE1 polarized light into the TE0 polarized light.

[0398] FIG38 is a third partially enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure. As shown in FIG38 , in some embodiments, the mode coupling portion 730 includes a first coupling waveguide 731 and a second coupling waveguide 732. One end of the first coupling waveguide 731 is connected to the other end of the connection portion 720, and the second coupling waveguide 732 is located to the side of the first coupling waveguide 731, with a gap between the first coupling waveguide 731 and the second coupling waveguide 732. For example, in the direction shown in FIG38 , the second coupling waveguide 732 is located above the first coupling waveguide 731, with a gap between the upper side of the first coupling waveguide 731 and the upper side of the second coupling waveguide 732. Of course, in the embodiments of the present disclosure, the second coupling waveguide 732 may also be located below the first coupling waveguide 731. In the embodiment of the present disclosure, the first coupling waveguide 731 and the second coupling waveguide 732 generate a mode coupling effect, so that the TE1 polarized light output from the connection portion 720 is coupled to the second coupling waveguide 732 and converted into TE0 polarized light. The TE0 polarized light output from the connection portion 720 continues to be transmitted along the first coupling waveguide 731, thereby realizing the splitting of TE1 polarized light and TE0 polarized light.

[0399] In some embodiments, the width of one end of the first coupling waveguide 731 is greater than the width of the other end of the first coupling waveguide 731. Exemplarily, the first coupling waveguide 731 is a tapered waveguide, such as a symmetric tapered waveguide or an asymmetric tapered waveguide.

[0400] In some embodiments, the width of one end of the second coupling waveguide 732 is smaller than the width of the other end of the second coupling waveguide 732. Exemplarily, the second coupling waveguide 732 is a tapered waveguide, such as a symmetric tapered waveguide or an asymmetric tapered waveguide.

[0401] In some embodiments, the width of one end of the first coupling waveguide 731 is greater than the width of the other end of the second coupling waveguide 732 , and the width of the other end of the first coupling waveguide 731 is greater than the width of one end of the second coupling waveguide 732 .

[0402] In some embodiments, the polarization rotation beam splitter 700 includes a beam splitter 740, one end of which is connected to the mode coupling unit 730. The beam splitter 740 is used to split the two beams of TE0 polarized light output by the transmission mode coupling unit 730. The beam splitter 740 is used to facilitate the polarization rotation beam splitter 700 to split and output the two beams of TE0 polarized light.

[0403] Figure 39 is a partial enlarged view of a polarization-rotating beam splitter provided according to some embodiments of the present disclosure. As shown in Figure 39, in some embodiments, the beam splitting portion 740 includes a third waveguide 741 and a fourth waveguide 742. One end of the third waveguide 741 is connected to the other end of the first coupling waveguide 731, and one end of the fourth waveguide 742 is connected to the other end of the second coupling waveguide 732. The third waveguide 741 serves as one output end of the polarization-rotating beam splitter 700, outputting a beam of TE0 polarized light. The fourth waveguide 742 serves as the other output end of the polarization-rotating beam splitter 700, outputting another beam of TE0 polarized light. A gap is provided between the third waveguide 741 and the fourth waveguide 742, with the width of the gap at the other end being greater than the width at the first end. This effectively reduces coupling between the two beams of TE0 polarized light when the other ends of the third waveguide 741 and the fourth waveguide 742 are close to each other, thereby reducing crosstalk between the two beams of TE0 polarized light at the output end of the polarization-rotating beam splitter 700.

[0404] In some embodiments, the third waveguide 741 includes an epitaxial waveguide 7411, one end of which is connected to the other end of the first coupling waveguide 731, and the epitaxial waveguide 7411 extends away from the centerline of the other end of the first coupling waveguide 731. Exemplarily, the epitaxial waveguide 7411 extends away from the second coupling waveguide 732 to facilitate adjustment of the spacing between the third waveguide 741 and the fourth waveguide 742.

[0405] In some embodiments, the third waveguide 741 includes a first straight waveguide 7412, which is located at the end of the third waveguide 741 to facilitate coupling of the third waveguide 741 with other structures. For example, one end of the first straight waveguide 7412 is connected to the other end of the epitaxial waveguide 7411. The epitaxial waveguide 7411 provides a smooth transition from the other end of the first coupling waveguide 731 to one end of the first straight waveguide 7412, gradually increasing the gap between the third waveguide 741 and the fourth waveguide 742.

[0406] In some embodiments, the epitaxial waveguide 7411 adopts Bessel bending waveguide, Euler bending waveguide, arc waveguide, etc., so that the epitaxial waveguide 7411 extends smoothly, effectively reducing the sharp points on the epitaxial waveguide 7411 and causing light beam reflection damage.

[0407] In some embodiments, the fourth waveguide 742 includes a second straight waveguide 7421, one end of which is connected to the other end of the second coupling waveguide 732. The second straight waveguide 7421 is located at the end of the fourth waveguide 742 to facilitate coupling between the fourth waveguide 742 and other structures.

[0408] In some embodiments, one end of the epitaxial waveguide 7411 is close to the second straight waveguide 7421 , and the other end of the epitaxial waveguide 7411 is far away from the second straight waveguide 7421 .

[0409] In some embodiments, the fourth waveguide 742 may include an outer waveguide, one end of which is connected to the other end of the second coupling waveguide 732, and the outer waveguide extends away from the centerline of the other end of the second coupling waveguide 732. For example, the outer waveguide extends away from the first coupling waveguide 732 to facilitate adjustment of the spacing between the third waveguide 741 and the fourth waveguide 742.

[0410] In some embodiments, the mode conversion portion 710 , the connection portion 720 , the mode coupling portion 730 , and the beam splitting portion 740 form a beam splitting waveguide layer 700 a .

[0411] FIG40 is a second structural diagram of a polarization rotation beam splitter according to some embodiments of the present disclosure. As shown in FIG40 , the polarization rotation beam splitter 700 includes a substrate 750 , and a beam splitting waveguide layer 700 a is disposed on the substrate 750 .

[0412] In some embodiments, the substrate 750 includes a first substrate layer 751 and a second substrate layer 752 . The second substrate layer 752 is disposed on the first substrate layer 751 , and the beam splitting waveguide layer 700 a is disposed on the second substrate layer 752 .

[0413] In some embodiments, the polarization-rotating beam splitter 700 includes a cladding layer 760 wrapped around the sides of the beam-splitting waveguide layer 700a.

[0414] In some embodiments, the structure of the beam splitting waveguide layer 700a can use materials such as Si, SiN, InP, lithium niobate (LiNbO3), etc., the first substrate layer 751 uses materials such as Si, the second substrate layer 752 uses materials such as SiO2, and the cladding 760 uses materials such as SiO2.

[0415] Figure 41 is a cross-sectional view taken along line BB in Figure 36, and Figure 42 is a cross-sectional view taken along line CC in Figure 36. Figures 41 and 42 illustrate a cross-sectional view of a mode converter. As shown in Figures 41 and 42, the first waveguide 711 is a continuous, symmetrical tapered waveguide, and the second waveguide 712 is a continuous, symmetrical tapered waveguide. This means that the first waveguide 711 and the second waveguide 712 exhibit uniform variations. Of course, the disclosed embodiments are not limited to this. In some embodiments, the mode converter 710 has an axisymmetric structure.

[0416] FIG43 is a schematic diagram of the structure of a mode conversion portion provided according to some embodiments of the present disclosure. As shown in FIG43 , the first waveguide 711 includes multiple sections of first tapered waveguides 7111 connected in sequence, with the width of one end of the first tapered waveguide 7111 being smaller than the width of the other end of the first tapered waveguide 7111. Exemplarily, the first waveguide 711 includes a first tapered waveguide 7111a, a first tapered waveguide 7111b, and a first tapered waveguide 7111n. The first tapered waveguides 7111a, 7111b, and 7111n can have different lengths, and the side surfaces of the first tapered waveguides 7111a, 7111b, and 7111n can have different inclinations, resulting in the first waveguide 711 forming a discontinuous tapered waveguide structure.

[0417] In some embodiments, the multiple sections of first tapered waveguides 7111 in the first waveguide 711 may be symmetrical tapered waveguides, but are not limited to symmetrical tapered waveguides.

[0418] In some embodiments, the second waveguide 712 includes multiple sections of sequentially connected second tapered waveguides 7121, with the width of one end of the second tapered waveguide 7121 being greater than the width of the other end of the second tapered waveguide 7121. For example, the second waveguide 712 includes a second tapered waveguide 7121a, a second tapered waveguide 7121b, and a second tapered waveguide 7121n, etc. The second tapered waveguides 7121a, 7121b, and 7121n can have different lengths, and the side surfaces of the second tapered waveguides 7121a, 7121b, and 7121n can have different inclinations, making the second waveguide 712 a discontinuous tapered waveguide structure.

[0419] In some embodiments, the multiple sections of second tapered waveguides 7121 in the second waveguide 712 may be symmetrical tapered waveguides, but are not limited to symmetrical tapered waveguides.

[0420] Figure 44 is a cross-sectional view taken along the DD direction in Figure 10 , showing a cross-sectional structure of a connecting portion. As shown in Figure 44 , the width of the connecting portion 720 at the DD is smaller than the width of the first waveguide 711 at the CC.

[0421] Figure 45 is a cross-sectional view taken along the EE direction in Figure 10, Figure 46 is a cross-sectional view taken along the FF direction in Figure 11, and Figure 47 is a partially enlarged view of a polarization rotation beam splitter provided according to some embodiments of the present disclosure. Figures 45-47 illustrate the structure of a mode coupling portion. As shown in Figures 45-47, the first coupling waveguide 731 includes a first side surface 7311, which is located on the side of the first coupling waveguide 731 facing the second coupling waveguide 732; the second coupling waveguide 732 includes a second side surface 7321, which is located on the side of the second coupling waveguide 732 facing the first coupling waveguide 731. The spacing between the first side surface 7311 and the second side surface 7321 is a first preset value, which is approximately 0.3 μm. Exemplarily, the first preset value is greater than 0 μm and less than 0.3 μm, such as 0.1 μm, 0.15 μm, 0.2 μm, etc.

[0422] In some embodiments, the mode coupling portion 730 further includes a curved waveguide 733, which is disposed at one end of the second coupling waveguide 732. Exemplarily, one end of the curved waveguide 733 is distal to a side edge of the connecting portion 720, and the other end of the curved waveguide 733 is connected to one end of the second coupling waveguide 732. One end of the curved waveguide 733 extends away from the connecting portion 720. The curved waveguide 733 is used to reduce the coupling of light from the second coupling waveguide 732 to the connecting portion 720, thereby ensuring the performance of the polarization rotation beam splitter.

[0423] In some embodiments, the curved waveguide 733 may be an arc waveguide or a spiral waveguide.

[0424] In some embodiments, the curved waveguide 733 is located on the side of the straight waveguide 722 to increase the distance between the curved waveguide 733 and the straight waveguide 722 and reduce the coupling of the light beam from the second coupling waveguide 732 to the straight waveguide 722 .

[0425] In some embodiments, the first side surface 7311 is a continuous and flat side surface, and the second side surface 7321 is a continuous and flat side surface. For example, the first coupling waveguide 731 is a symmetrical tapered waveguide, forming a continuous first side surface 7311 along the side of the first coupling waveguide 731; and the second coupling waveguide 732 is a symmetrical tapered waveguide, forming a continuous second side surface 7321 along the side of the second coupling waveguide 732. Of course, in the disclosed embodiments, the first coupling waveguide 731 and the second coupling waveguide 732 are not limited to symmetrical tapered waveguides.

[0426] Figure 48 is a structural diagram of another mode coupling section provided according to some embodiments of the present disclosure. Figure 48 (a) and (b) respectively illustrate a mode coupling section structure. As shown in Figure 48, in the mode coupling section 730, the first coupling waveguide 731 and the second coupling waveguide 732 are both asymmetric tapered waveguides; alternatively, the first coupling waveguide 731 is a symmetric tapered waveguide, and the second coupling waveguide 732 is an asymmetric tapered waveguide. Of course, in the embodiments of the present disclosure, the configurations of the first coupling waveguide 731 and the second coupling waveguide 732 are not limited to these.

[0427] Figure 49 is a structural diagram of another mode coupling portion provided according to some embodiments of the present disclosure, illustrating a multi-segment mode coupling portion. As shown in Figure 49, in some embodiments, the first coupling waveguide 731 comprises multiple waveguide segments, which are sequentially connected. These multiple waveguide segments include multiple tapered waveguides, straight waveguides, and the like. The sides of the multiple waveguide segments are sequentially connected to form an uneven first side surface 7311, meaning that the first side surface 7311 comprises multiple sequentially connected side surfaces.

[0428] In some embodiments, in the first coupling waveguide 731, one side of the multi-section waveguide is respectively provided with a first sub-side surface 7311a, a first sub-side surface 7311b, a first sub-side surface 7311c, etc., and the first sub-side surface 7311a, the first sub-side surface 7311b, the first sub-side surface 7311c, etc. are connected in sequence to form the first side surface 7311.

[0429] In some embodiments, the second coupling waveguide 732 includes multiple waveguide segments connected in sequence, including multiple tapered waveguide segments, straight waveguide segments, and the like. The sides of the multiple waveguide segments are sequentially connected to form an uneven second side surface 7321, i.e., the second side surface 7321 includes multiple sequentially connected side surfaces.

[0430] In some embodiments, in the second coupling waveguide 732, a second sub-side surface 7321a, a second sub-side surface 7321b, a second sub-side surface 7321c, etc. are respectively provided on one side of the multi-section waveguide, and the second sub-side surface 7321a, the second sub-side surface 7321b, the second sub-side surface 7321c, etc. are connected in sequence to form the second side surface 7321.

[0431] In some embodiments, the interval between the first sub-side 7311a and the second sub-side 7321a is a first preset value, the interval between the first sub-side 7311b and the second sub-side 7321b is a first preset value, the interval between the first sub-side 7311c and the second sub-side 7321c is a first preset value, and so on.

[0432] Figure 50 is a cross-sectional view taken along the GG direction in Figure 39 , illustrating a cross-sectional structure of a beam splitter. As shown in Figure 50 , the spacing between the first straight waveguide 7412 and the second straight waveguide 7421 is greater than the width of the first straight waveguide 7412 , and the spacing between the first straight waveguide 7412 and the second straight waveguide 7421 is greater than the width of the second straight waveguide 7421 .

[0433] 50 and the cross-sectional view shown in FIG46 , the interval between the first straight waveguide 7412 and the second straight waveguide 7421 is greater than the first preset value. For example, the interval between the first straight waveguide 7412 and the second straight waveguide 7421 is 10 times the first preset value.

[0434] In some embodiments, based on the principle of optical path reversibility, two beams of TE0 polarized light are inputted from the ends of the beam splitter 740, thereby multiplexing the two beams of TE0 polarized light into a single beam of polarized light comprising TM0 polarized light and TE0 polarized light. This is achieved by utilizing the polarization rotating beam splitter 700 to achieve polarization rotation and beam combining. Specifically, a beam of TE0 polarized light is inputted from the end of the fourth waveguide 742, propagates in the opposite direction of the polarization rotating beam splitter 700, undergoes mode hybridization in the polarization rotating beam splitter 700, and finally outputs TM0 polarized light at one end of the mode converter 710. A beam of TE0 polarized light is inputted from the end of the third waveguide 741, propagates in the opposite direction of the polarization rotating beam splitter 700, and is output at one end of the mode converter 710. At one end of the mode converter 710, the TM0 polarized light and the TE0 polarized light are combined into one beam.

[0435] Based on the second waveguide 712, the polarization rotation beam splitter 700 provided in the disclosed embodiment is easily applicable to optical links with thicker waveguide layers, such as heterogeneous integrated optoelectronic chips. The polarization rotation beam splitter 700 provided in the disclosed embodiment has an easily processable structure, a small device size, a large manufacturing tolerance, and good operating bandwidth performance, with low loss and a good polarization extinction ratio. The polarization rotation beam splitter 700 provided in the disclosed embodiment is not limited to use in the optical chip 400 provided in the above embodiment, but can also be used in other optical chips that involve polarization multiplexing of optical beams.

[0436] 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; A light source, comprising a laser component, the laser component is electrically connected to the circuit board, the laser component comprises a semiconductor gain chip and a wavelength tuning chip, the semiconductor gain chip is configured to emit a light beam in a wavelength range, the wavelength tuning chip and the semiconductor gain chip form a resonant cavity; wherein the wavelength tuning chip comprises: an input coupler configured to receive a light beam emitted by the semiconductor gain chip and transmit a light beam of a specific wavelength to the semiconductor gain chip; a power splitter connected to the input coupler, the power splitter being configured to split the light beam input by the input coupler; at least one micro-ring filter connected to the output end of the power divider, wherein the micro-ring filter is configured to filter out a light beam of a specific wavelength from the light beams in the wavelength range; The microring filter comprises a silicon waveguide ridge region, a first flat plate region and a second flat plate region; the silicon waveguide ridge region is configured to transmit a light beam and generate electron-hole pairs when transmitting the light beam; the first flat plate region is located on one side of the silicon waveguide ridge region, and an N-type doped region is provided in the first flat plate region; the second flat plate region is located on the other side of the silicon waveguide ridge region, and a P-type doped region is provided in the second flat plate region, and the P-type doped region and the N-type doped region form a PN junction, and the PN junction is configured to absorb the electron-hole pairs in the silicon waveguide ridge region, the first flat plate region and the second flat plate region; an optical chip, electrically connected to the circuit board, the optical chip being configured to receive an external optical signal; an optical fiber configured to transmit the external optical signal; A coupler component is coupled to the optical fiber, and the coupler component is configured to couple an external optical signal transmitted by the optical fiber to the optical chip; wherein the coupler component includes: a first coupling waveguide, one end of which is coupled to the optical fiber, and the first coupling waveguide is configured to receive an external optical signal transmitted by the optical fiber; a second coupling waveguide configured to couple the external optical signal to the optical chip; At least one transition waveguide is located between the first coupling waveguide and the second coupling waveguide, and the at least one transition waveguide is configured to couple the external optical signal transmitted by the first coupling waveguide to the second coupling waveguide.

2. The optical module according to claim 1, wherein: The microring filter also includes: a silicon substrate, a covering layer and a contact electrode; the covering layer is arranged on the silicon substrate along the epitaxial growth direction; the silicon waveguide ridge region and the contact electrode are both located in the covering layer, and the contact electrode is electrically connected to the P-type doped region and the N-type doped region to provide a reverse bias to the PN junction.

3. The optical module according to claim 2, wherein: At least one microring filter comprises: A first micro-ring filter connected to the first output end of the power divider; A second microring filter is connected to the second output end of the power divider. The second microring filter is connected in series with the first microring filter. The circumference of the second microring filter is different from that of the first microring filter. The second microring filter cooperates with the first microring filter to screen out a light beam of a specific wavelength from the split light.

4. The optical module according to claim 2, wherein: The contact electrode includes a first contact electrode and a second contact electrode, the first contact electrode is electrically connected to the N-type doping region, the second contact electrode is electrically connected to the P-type doping region, the first contact electrode is connected to a first voltage, the second contact electrode is connected to a second voltage, and the first voltage is greater than the second voltage to apply a reverse bias to the PN junction.

5. The optical module according to claim 4, wherein: Along the epitaxial growth direction, the first contact electrode is disposed on the first flat plate region, and the second contact electrode is disposed on the second flat plate region.

6. The optical module according to claim 2, wherein: There is a first preset distance between the N-type doped region and the edge of the silicon waveguide ridge region facing the first flat plate region, and there is a second preset distance between the P-type doped region and the edge of the silicon waveguide ridge region facing the second flat plate region, and the first preset distance is equal to the second preset distance.

7. The optical module according to claim 6, wherein: The first preset distance ranges from 500 nm to 1 μm.

8. The optical module according to claim 7, wherein: The first preset distance is 0.8 μm.

9. The optical module according to claim 2, wherein: The microring filter further includes a heater, which is disposed on the cover layer along the epitaxial growth direction and is configured to heat the silicon waveguide ridge region to change the refractive index of the microring filter.

10. The optical module according to claim 2, wherein: The wavelength tuning chip is a silicon photonic chip, and the covering layer is a silicon oxide covering layer.

11. The optical module according to claim 2, wherein: The first slab region is located outside the silicon waveguide ridge region, the first slab region surrounds the silicon waveguide ridge region, and the N-type doped region surrounds the silicon waveguide ridge region; The second slab region is located inside the silicon waveguide ridge region, the silicon waveguide ridge region surrounds the second slab region, and the silicon waveguide ridge region surrounds the P-type doping region.

12. The optical module according to claim 1, wherein: The coupler assembly is a waveguide coupler; The waveguide coupler comprises: substrate; A first cladding layer is arranged on the substrate along the epitaxial growth direction; A second cladding layer is arranged on the first cladding layer along the epitaxial growth direction, the refractive index of the substrate is greater than the refractive index of the second cladding layer, and the refractive index of the second cladding layer is greater than the refractive index of the first cladding layer; The first coupled waveguide and the second coupled waveguide are both located in the second cladding; A first gap is provided between the first coupling waveguide and the at least one transition waveguide, a first overlapping portion is provided between the first coupling waveguide and the at least one transition waveguide, a second gap is provided between the second coupling waveguide and the at least one transition waveguide, a second overlapping portion is provided between the second coupling waveguide and the at least one transition waveguide, the second gap is smaller than the first gap, and a length of the second overlapping portion is smaller than a length of the first overlapping portion.

13. The optical module according to claim 12, wherein: The waveguide coupler comprises a first transition waveguide, a first gap is formed between the first coupling waveguide and the first transition waveguide, a second gap is formed between the second coupling waveguide and the first transition waveguide, and the first gap is larger than the second gap; A first overlapping portion is provided between the first coupling waveguide and the first transition waveguide, and a second overlapping portion is provided between the second coupling waveguide and the first transition waveguide. The length of the first overlapping portion is greater than the length of the second overlapping portion.

14. The optical module according to claim 13, wherein: The size of the first gap is 1.5 μm, and the length of the first overlapped portion is 600 μm; The size of the second gap is 0.78 μm, and the length of the second overlapped portion is 300 μm.

15. The optical module according to claim 12, wherein: The waveguide coupler comprises a first transition waveguide and a second transition waveguide, wherein one end of the first transition waveguide is coupled to the first coupling waveguide, the other end of the first transition waveguide is coupled to one end of the second transition waveguide, and the other end of the second transition waveguide is coupled to the second coupling waveguide; There is a first gap between the first coupling waveguide and the first transition waveguide, there is a second gap between the second transition waveguide and the second coupling waveguide, there is a third gap between the first transition waveguide and the second transition waveguide, the second gap is smaller than the first gap, and the second gap is smaller than the third gap; There is a first overlapping portion between the first coupling waveguide and the first transition waveguide, there is a second overlapping portion between the second coupling waveguide and the second transition waveguide, there is a third overlapping portion between the first transition waveguide and the second transition waveguide, the length of the second overlapping portion is smaller than the length of the first overlapping portion, and the length of the second overlapping portion is smaller than the length of the third overlapping portion.

16. The optical module according to claim 15, wherein: The first gap is larger than the third gap, and the length of the first overlapping portion is larger than the length of the third overlapping portion; or, the first gap is smaller than the third gap, and the length of the first overlapping portion is smaller than the length of the third overlapping portion.

17. The optical module according to claim 15, wherein: The size of the first gap is in the range of 0.5 to 2 μm, the size of the second gap is in the range of 0.1 to 0.8 μm, and the size of the third gap is in the range of 0.5 to 2 μm.

18. The optical module according to claim 17, wherein: The size of the first gap is 1.3 μm, and the length of the first overlapping portion between the first coupling waveguide and the first transition waveguide is 400 μm; The size of the second gap is 0.43 μm, and the length of the second overlapping portion between the second coupling waveguide and the second transition waveguide is 100 μm; The size of the third gap is 0.85 μm, and the length of the third overlapping portion between the first transition waveguide and the second transition waveguide is 200 μm.

19. The optical module according to claim 12, wherein: The waveguide coupler further comprises: The third cladding is arranged on the second cladding along the epitaxial growth direction. The thickness of the third cladding is smaller than the thickness of the second cladding. The refractive index of the third cladding is the same as the refractive index of the first cladding.

20. The optical module according to claim 15, wherein: The first coupling waveguide includes a first tapered waveguide and a second tapered waveguide connected to each other, and the tip of the first tapered waveguide is coupled to the optical fiber; A second coupling waveguide, wherein the second coupling waveguide includes a connection between the seventh tapered waveguide and the straight waveguide, wherein the straight waveguide is adjacent to the optical chip; the waveguide coupler further includes a side groove, wherein the side groove is located in the first cladding and the second cladding, and the side groove is located on both sides of the first coupling waveguide and the second coupling waveguide.

21. The optical module according to claim 20, wherein: The first transition waveguide includes a third tapered waveguide and a fourth tapered waveguide connected to each other, and a first overlapping portion exists between the third tapered waveguide and the second tapered waveguide; The second transition waveguide includes a fifth tapered waveguide and a sixth tapered waveguide connected to each other, the fifth tapered waveguide and the fourth tapered waveguide have a third overlapping portion, the sixth tapered waveguide and the seventh tapered waveguide have a second overlapping portion, the length of the second overlapping portion is smaller than the length of the first overlapping portion, and the length of the second overlapping portion is smaller than the length of the third overlapping portion.

22. An optical module, comprising: Circuit boards; A light source, comprising a laser component, the laser component is electrically connected to the circuit board, the laser component comprises a semiconductor gain chip and a wavelength tuning chip, the semiconductor gain chip is used to emit a light beam in a wavelength range, the wavelength tuning chip and the semiconductor gain chip form a resonant cavity; wherein the wavelength tuning chip comprises: An input coupler, used to receive the light beam emitted by the semiconductor gain chip and transmit a light beam of a specific wavelength to the semiconductor gain chip; a power splitter connected to the input coupler, the power splitter being used to split the light beam input by the input coupler; At least one micro-ring filter is connected to the output end of the power divider, and the micro-ring filter is used to filter out a light beam of a specific wavelength from the light beams in the wavelength range; wherein the micro-ring filter comprises: Silicon substrate; A covering layer is arranged on the silicon substrate along the epitaxial growth direction; A silicon waveguide ridge region, located in the cover layer, the silicon waveguide ridge region is used to transmit the light beam and generate electron-hole pairs when transmitting the light beam; A first slab region, located at one side of the silicon waveguide ridge region, wherein an N-type doped region is disposed in the first slab region; A second slab region is located at the other side of the silicon waveguide ridge region, wherein a P-type doping region is provided in the second slab region, wherein the P-type doping region and the N-type doping region form a PN junction, wherein the PN junction is used to absorb electron-hole pairs in the silicon waveguide ridge region, the first slab region and the second slab region; A contact electrode is located in the cover layer, and the contact electrode is electrically connected to the P-type doping region and the N-type doping region to provide a reverse bias voltage to the PN junction.

23. The optical module according to claim 22, wherein: At least one microring filter comprises: A first micro-ring filter connected to the first output end of the power divider; A second microring filter is connected to the second output end of the power divider. The second microring filter is connected in series with the first microring filter. The circumference of the second microring filter is different from that of the first microring filter. The second microring filter cooperates with the first microring filter to screen out a light beam of a specific wavelength from the split light.

24. The optical module according to claim 22, wherein: The contact electrode includes a first contact electrode and a second contact electrode, the first contact electrode is electrically connected to the N-type doping region, the second contact electrode is electrically connected to the P-type doping region, the first contact electrode is connected to a first voltage, the second contact electrode is connected to a second voltage, and the first voltage is greater than the second voltage to apply a reverse bias to the PN junction.

25. The optical module according to claim 24, wherein: Along the epitaxial growth direction, the first contact electrode is disposed on the first flat plate region, and the second contact electrode is disposed on the second flat plate region.

26. The optical module according to claim 22, wherein: There is a first preset distance between the N-type doped region and the edge of the silicon waveguide ridge region facing the first flat plate region, and there is a second preset distance between the P-type doped region and the edge of the silicon waveguide ridge region facing the second flat plate region, and the first preset distance is equal to the second preset distance.

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