An optical module

Abstract

The optical module provided by the application comprises a circuit board, an optical emission sub-module and a flexible circuit board. The optical emission sub-module comprises a shell and a ceramic adapter block plated with a metal layer. One side of the ceramic adapter block is inserted into the shell, and the other side is exposed outside the shell. The metal layer of the ceramic adapter block is provided with signal and ground pads. The signal pads on the inside and outside of the ceramic adapter block are connected. An isolation groove is arranged between the signal and ground pads on the ceramic adapter block outside the shell. The isolation groove is recessed in the signal and ground pads. One end of the flexible circuit board is connected to the ceramic adapter block, and the other end is connected to the circuit board. The application sets the isolation groove between the signal pad and the ground pad on the ceramic adapter block exposed outside the shell. The isolation groove is recessed in the signal pad. The dielectric constant of the ceramic adapter block is reduced through the isolation groove, the impedance discontinuity point at the connection between the flexible circuit board and the ceramic adapter block is reduced, the signal transmission quality is improved, and the signal integrity is ensured.

Description

Technical Field

[0001] This application relates to the field of optical fiber communication technology, and in particular to an optical module. Background Technology

[0002] With the development of new business and application models such as cloud computing, mobile internet, and video, the advancement of optical communication technology has become increasingly important. In optical communication technology, optical modules are the tools for converting between photoelectric signals and signals, and are one of the key components in optical communication equipment. Furthermore, with the evolving needs of optical communication technology, the transmission rate of optical modules is constantly increasing.

[0003] Optical modules typically consist of a circuit board and an optical sub-module. The optical sub-module can be hermetically sealed or non-hermetically sealed. In high-speed products, the optical sub-module is usually hermetically sealed, with the hermetically sealed housing connected to the circuit board via a flexible circuit board. Therefore, the hermetically sealed housing and the flexible circuit board need to be interconnected. The solder pads for this interconnection use the GSG (Glass Gap) pattern, and the housing and flexible circuit board must be connected by solder. The width of the solder pads must be sufficient for successful soldering. This inevitably leads to impedance discontinuities at the solder joints between the housing and the flexible circuit board, resulting in changes in signal quality and reduced signal integrity. Summary of the Invention

[0004] This application provides an optical module to solve the problem that impedance discontinuities exist at the solder joint between the hermetic housing pads and the flexible circuit board pads of current optical modules, resulting in poor signal integrity.

[0005] This application provides an optical module, comprising:

[0006] Circuit board;

[0007] A light-emitting submodule includes a housing and a ceramic adapter block coated with a metal layer. One side of the housing has an opening, through which one side of the ceramic adapter block is inserted into the housing, while the other side protrudes from the outside of the housing. Signal pads and ground pads are arranged side-by-side on the metal layer of the ceramic adapter block, and the signal pads on the inner and outer sides of the ceramic adapter block are connected. An isolation groove is provided on the ceramic adapter block, located on the outer side of the housing, between the signal pads and the ground pads, and the isolation groove is recessed into the signal pads and the ground pads.

[0008] The flexible circuit board has one end connected to the ceramic adapter block via the signal pad and the ground pad, and the other end connected to the circuit board.

[0009] The optical module provided in this application includes a circuit board, an optical emitting sub-module, and a flexible circuit board. The optical emitting sub-module includes a housing and a ceramic adapter block coated with a metal layer. One side of the housing has an opening, and one side of the ceramic adapter block is inserted into the housing through the opening, while the other side is exposed on the outside of the housing. In this way, the ceramic adapter block is inserted into the housing to hermetically seal the optical emitting component of the optical emitting sub-module. Signal pads and ground pads are arranged side by side on the metal layer of the ceramic adapter block. The signal pads on the inner and outer sides of the ceramic adapter block are connected to realize signal transmission between the inner and outer sides of the ceramic adapter block. An isolation groove is provided between the signal pad and the ground pad on the outer side of the housing on the ceramic adapter block. The isolation groove is recessed into the signal pad and the ground pad. One end of the flexible circuit board is connected to the ceramic adapter block through the signal pad and the ground pad, and the other end is connected to the circuit board. In the optical module provided in this application, one end of the ceramic adapter block is inserted into the housing to form an hermetically sealed tube, while the other end protrudes outside the housing. The ceramic adapter block protruding outside the housing is directly soldered to the flexible circuit board via signal pads and ground pads on it. An isolation groove is provided on the ceramic adapter block between the signal pads and ground pads on the outer shell of the housing, and the isolation groove is recessed into the signal pads. The ceramic adapter block, which is plated with a metal layer, achieves electrical connection between the inner and outer sides of the ceramic adapter block. The inner side of the ceramic adapter block is electrically connected to the optical emitting component, and the outer side is electrically connected to the flexible circuit board. The isolation groove is provided on the side where the ceramic adapter block connects to the flexible circuit board, which can reduce the dielectric constant of the ceramic adapter block, thereby reducing impedance discontinuities at the connection between the flexible circuit board and the ceramic adapter block, thus improving signal transmission quality and ensuring signal integrity. In addition, the isolation groove is located on the end face of the ceramic adapter block protruding outside the housing, which does not affect the hermetically sealed packaging of the optical emitting sub-module. Attached Figure Description

[0010] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the connection relationship between optical communication terminals;

[0012] Figure 2 This is a schematic diagram of an optical network unit structure;

[0013] Figure 3 This is a schematic diagram of an optical module structure provided in an embodiment of this application;

[0014] Figure 4 This is a schematic diagram of the exploded structure of an optical module provided in an embodiment of this application;

[0015] Figure 5This is an assembly diagram of an optical module and a flexible circuit board in an optical module provided in an embodiment of this application;

[0016] Figure 6 An exploded view of an optical emitting submodule in an optical module provided in an embodiment of this application;

[0017] Figure 7 This is a schematic diagram illustrating the assembly of a laser component, a ceramic adapter block, and a flexible circuit board in an optical module, as provided in an embodiment of this application.

[0018] Figure 8 This is a schematic diagram illustrating the assembly of a ceramic adapter block and a flexible circuit board in an optical module, provided as an embodiment of this application.

[0019] Figure 9 An exploded view of a ceramic adapter block and a flexible circuit board in an optical module provided in an embodiment of this application;

[0020] Figure 10 This is a schematic diagram of the structure of a ceramic adapter block in an optical module provided in an embodiment of this application;

[0021] Figure 11 This is a schematic diagram of another angle of the structure of a ceramic adapter block in an optical module provided in an embodiment of this application;

[0022] Figure 12 This is a partial structural diagram of a ceramic adapter block in an optical module provided in an embodiment of this application. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] One of the core aspects of fiber optic communication is the conversion between optical and electrical signals. Fiber optic communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers / waveguides. The passive transmission characteristics of light in optical fibers / waveguides enable low-cost, low-loss information transmission. In contrast, information processing equipment such as computers uses electrical signals. Therefore, in order to establish an information connection between information transmission equipment such as optical fibers / waveguides and information processing equipment such as computers, it is necessary to achieve the conversion between electrical and optical signals.

[0025] In the field of fiber optic communication technology, optical modules realize the mutual conversion between optical and electrical signals, which is the core function of optical modules. Optical modules achieve electrical connection with external host computers through gold fingers on their internal circuit boards. The main electrical connections include power supply, I2C signals, data signals, and grounding. The gold finger-based electrical connection method has become the mainstream connection method in the optical module industry. Based on this, the pin definitions on the gold fingers have formed various industry protocols / standards.

[0026] Figure 1 This is a schematic diagram illustrating the connection relationships between optical communication terminals. For example... Figure 1 As shown, the connection of the optical communication terminal mainly includes the interconnection between the optical network terminal 100, the optical module 200, the optical fiber 101, and the network cable 103.

[0027] One end of the optical fiber 101 is connected to the remote server, and one end of the network cable 103 is connected to the local information processing device. The connection between the local information processing device and the remote server is completed by the connection between the optical fiber 101 and the network cable 103. The connection between the optical fiber 101 and the network cable 103 is completed by the optical network terminal 100 with the optical module 200.

[0028] The optical port of the optical module 200 is connected to the optical fiber 101, establishing a bidirectional optical signal connection with the optical fiber 101; the electrical port of the optical module 200 is connected to the optical network terminal 100, establishing a bidirectional electrical signal connection with the optical network terminal 100; the optical module internally realizes the mutual conversion between optical signals and electrical signals, thereby realizing the establishment of an information connection between the optical fiber and the optical network terminal; specifically, the optical signal from the optical fiber is converted into an electrical signal by the optical module and then input into the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module and then input into the optical fiber.

[0029] The optical network terminal has an optical module interface 102 for connecting to the optical module 200 and establishing a bidirectional electrical signal connection with the optical module 200; the optical network terminal has a network cable interface 104 for connecting to the network cable 103 and establishing a bidirectional electrical signal connection with the network cable 103; the optical module 200 and the network cable 103 are connected through the optical network terminal 100. Specifically, the optical network terminal transmits signals from the optical module to the network cable and transmits signals from the network cable to the optical module. The optical network terminal acts as a host computer for the optical module to monitor the operation of the optical module.

[0030] At this point, the remote server establishes a two-way signal transmission channel with the local information processing equipment via optical fiber, optical module, optical network terminal and network cable.

[0031] Common information processing equipment includes routers, switches, and computers; optical network terminals are the host computers of optical modules, providing data signals to and receiving data signals from optical modules. Other common host computers for optical modules include optical line terminals.

[0032] Figure 2 This is a schematic diagram of an optical network terminal structure. (Example) Figure 2 As shown, the optical network terminal 100 has a circuit board 105, and a cage 106 is provided on the surface of the circuit board 105; an electrical connector is provided inside the cage 106 for connecting to the electrical port of the optical module such as the gold finger; a heat sink 107 is provided on the cage 106, and the heat sink 107 has fins and other protrusions to increase the heat dissipation area.

[0033] The optical module 200 is inserted into the optical network terminal. Specifically, the electrical port of the optical module is inserted into the electrical connector inside the cage 106, and the optical port of the optical module is connected to the optical fiber 101.

[0034] The cage 106 is located on the circuit board and encloses the electrical connectors on the circuit board inside the cage, thus providing electrical connectors inside the cage; the optical module is inserted into the cage and fixed by the cage, and the heat generated by the optical module is conducted to the cage 106 and then diffused through the heat sink 107 on the cage.

[0035] Figure 3 This is a schematic diagram of an optical module structure provided in an embodiment of this application. Figure 4 This application provides an exploded view of the optical module's structure as an embodiment. Figure 3 , Figure 4 As shown, the optical module 200 provided in this application embodiment includes an upper housing 201, a lower housing 202, an unlocking component 203, a circuit board 300, an optical transmitting sub-module 400, and an optical receiving sub-module 500.

[0036] The upper housing 201 covers the lower housing 202 to form a wrapping cavity with two openings. The outer contour of the wrapping cavity is generally square. Specifically, the lower housing includes a main board and two side plates located on both sides of the main board and perpendicular to the main board. The upper housing includes a third housing, which covers the two side plates of the upper housing to form the wrapping cavity. The upper housing may also include two side walls located on both sides of the third housing and perpendicular to the third housing. The two side walls are combined with the two side plates to realize that the upper housing covers the lower housing.

[0037] The two openings can be at opposite ends in the same direction (204, 205), or they can be at two different locations in different directions. One opening is an electrical port 204, through which the gold fingers of the circuit board extend and are inserted into a host computer such as an optical network terminal. The other opening is an optical port 205, used for external fiber optic access to connect to the optical transmitting sub-module 400 and optical receiving sub-module 500 inside the optical module. The circuit board 300, the optical transmitting sub-module 400, the optical receiving sub-module 500, and other optoelectronic devices are located in the encapsulated cavity.

[0038] The assembly method using an upper and lower housing facilitates the installation of components such as the circuit board 300, the optical transmitting sub-module 400, and the optical receiving sub-module 500 into the housing. The upper and lower housings form the outermost protective enclosure of the optical module. The upper and lower housings are generally made of metal materials, which is beneficial for electromagnetic shielding and heat dissipation. The housing of the optical module is generally not made into a single component, as this would prevent the installation of positioning components, heat dissipation, and electromagnetic shielding components when assembling circuit boards and other components, and would also hinder production automation.

[0039] The unlocking component 203 is located on the outer wall of the enclosing cavity / lower housing 202 and is used to realize the fixed connection between the optical module and the host computer, or to release the fixed connection between the optical module and the host computer.

[0040] The unlocking component 203 has a locking component that matches the host computer cage; pulling the end of the unlocking component allows the unlocking component to move relative to the surface of the outer wall; the optical module is inserted into the host computer cage, and the locking component of the unlocking component fixes the optical module in the host computer cage; by pulling the unlocking component, the locking component of the unlocking component moves accordingly, thereby changing the connection relationship between the locking component and the host computer, so as to release the locking relationship between the optical module and the host computer, thereby allowing the optical module to be pulled out of the host computer cage.

[0041] The circuit board 300 is equipped with circuit traces, electronic components (such as capacitors, resistors, transistors, and MOSFETs) and chips (such as MCUs, laser driver chips, limiting amplifier chips, clock data recovery CDRs, power management chips, and data processing chips DSPs).

[0042] The circuit board connects the electrical components in the optical module according to the circuit design through circuit traces to realize electrical functions such as power supply, electrical signal transmission and grounding.

[0043] The chip on circuit board 300 can be a multi-functional integrated chip, such as integrating a laser driver chip and an MCU chip into one chip, or integrating a laser driver chip, a limiting amplifier chip, and an MCU chip into one chip. A chip is an integration of circuits, but the functions of each circuit do not disappear due to integration; only the circuit's form changes, and the chip still retains that circuit form. Therefore, having three independent chips—an MCU, a laser driver chip, and a limiting amplifier chip—on the circuit board is equivalent to having a single three-functional integrated chip on circuit board 300.

[0044] Circuit boards are generally rigid circuit boards. Due to their relatively rigid material, rigid circuit boards can also perform load-bearing functions. For example, rigid circuit boards can stably support chips. When optical transceivers are located on the circuit board, rigid circuit boards can also provide stable support. Rigid circuit boards can also be inserted into electrical connectors in the host computer cage. Specifically, metal pins / gold fingers are formed on one end surface of the rigid circuit board for connection with electrical connectors. These are things that flexible circuit boards cannot easily achieve.

[0045] Flexible circuit boards are also used in some optical modules as a supplement to rigid circuit boards. Flexible circuit boards are generally used in conjunction with rigid circuit boards, such as connecting rigid circuit boards to optical transceivers.

[0046] In order to improve the transmission rate of the optical module and adapt to various harsh environments, the optical transmitting sub-module 400 and the optical receiving sub-module of the optical module need to be hermetically sealed. Therefore, the optical transmitting sub-module 400 and the optical receiving sub-module 500 usually adopt a hermetically sealed shell packaging structure.

[0047] Figure 5 This is a schematic diagram of the assembly of the optical emission submodule 400 and the flexible circuit board provided in an embodiment of this application. Figure 6 This is an exploded view of the optical emission sub-module 400 and the flexible circuit board provided in an embodiment of this application. Figure 5 , Figure 6 As shown, the optical emission sub-module 400 provided in this embodiment includes a housing and a ceramic adapter block 430. The housing includes a cover plate 410 and a tube shell 420. The cover plate 410 covers the tube shell 420. The tube shell 420 has an opening on the side facing the circuit board 300. One side of the ceramic adapter block 430 is inserted into the tube shell 420 through the opening, and the other side is exposed outside the tube shell 420, so that the cover plate 410, the tube shell 420 and the ceramic adapter block 430 are assembled to form an airtight housing.

[0048] The optical emission submodule 400 includes a laser assembly 440, a lens array 450, a wavelength division multiplexing (WDM) assembly, and a lens assembly. These components are housed within an airtight enclosure composed of a cover plate 410, a housing 420, and a ceramic adapter block 430, and are arranged sequentially along the light emission direction. The laser assembly emits beams of various wavelengths. These beams are combined using the lens array 450, the WDM assembly, and the lens assembly. The combined beam is then transmitted to an external optical fiber via a fiber optic adapter to achieve beam emission.

[0049] Specifically, the laser assembly 440 includes multiple lasers, all positioned close to the ceramic adapter block 430, and each laser is connected to the ceramic adapter block 430 via gold wires. The ceramic adapter block 430 has pads at one end of the hermetic housing, and the lasers are connected to these pads via gold wires to achieve electrical connection between the laser assembly 440 and the ceramic adapter block 430 within the hermetic housing.

[0050] In this embodiment of the application, the laser assembly 440 includes 8 lasers, which are arranged sequentially along the front and back direction of the hermetic housing. The 8 lasers emit 8 laser beams of different wavelengths. The 8 laser beams of different wavelengths are combined by optical devices such as lens array 450, wavelength division multiplexing assembly, and lens assembly to obtain a composite beam. The composite beam is transmitted to an external optical fiber through an optical fiber adapter.

[0051] The lens array 450 includes eight collimating lenses, each collimating lens being configured corresponding to each laser and located in the light emission direction of the laser. In this way, the laser beam emitted by the laser is converted into a collimated beam by the collimating lens, and the collimated beam is injected into the wavelength division multiplexing component for light combining.

[0052] The wavelength division multiplexing (WDM) assembly includes a first WDM multiplexer 460 and a second WDM multiplexer 470. The first WDM multiplexer 460 is configured with four lasers and four collimating lenses. Four laser beams of different wavelengths emitted by the four lasers are directed into the first WDM multiplexer 460 through the collimating lenses. The second WDM multiplexer 470 is configured with another four lasers and four collimating lenses. Four laser beams of different wavelengths emitted by the other four lasers are directed into the second WDM multiplexer 470 through the collimating lenses.

[0053] The first wavelength division multiplexer 460 includes four input ports on the right side for receiving beams of multiple wavelengths, and one output port on the left side for receiving light. Each input port is used for receiving a beam of one wavelength. Specifically, multiple beams of different wavelengths enter the first wavelength division multiplexer 460 through their respective input ports. One beam undergoes six different reflections at six different locations within the first wavelength division multiplexer 460 before reaching the output port; another beam undergoes four different reflections at four different locations within the first wavelength division multiplexer 460 before reaching the output port; another beam undergoes two different reflections at two different locations within the first wavelength division multiplexer 460 before reaching the output port; and a beam is directly transmitted to the output port after entering the first wavelength division multiplexer 460. Thus, the first wavelength division multiplexer 460 enables beams of different wavelengths to enter the first wavelength division multiplexer 460 through different input ports and exit through the same output port, thereby achieving beam combining of different wavelength beams. In this embodiment, the first wavelength division multiplexer 460 is not limited to combining beams of four wavelengths, but can be selected according to actual needs.

[0054] The lens assembly includes a first lens assembly 480 and a second lens assembly 490. The first lens assembly 480 is disposed in the light output direction of the first wavelength division multiplexer 460, and the second lens assembly 490 is disposed in the light output direction of the second wavelength division multiplexer 470. The first composite beam emitted from the first wavelength division multiplexer 460 is reflected by the first lens assembly 480 to the second lens assembly 490. The second composite beam emitted from the second wavelength division multiplexer 470 enters the second lens assembly 490. The second lens assembly 490 combines the reflected first composite beam and the second composite beam into a single beam. The combined beam is then emitted into the fiber optic adapter.

[0055] Figure 7 This is a schematic diagram illustrating the assembly of a laser assembly 440, a ceramic adapter block 430, and a flexible circuit board in an optical module according to an embodiment of this application. Figure 7 As shown, one end of the ceramic adapter block 430 located inside the airtight housing is connected to each laser of the laser assembly 440 via gold wire, and the other end of the ceramic adapter block 430 located outside the airtight housing is connected to the circuit board 300 via a flexible circuit board. The electrical signals and working signals generated by the circuit board 300 are transferred to each laser through the flexible circuit board and the ceramic adapter block 430 to drive each laser to emit laser beams of different wavelengths.

[0056] In order to achieve electrical connection between the inside and outside of the housing through the ceramic adapter block 430, a metal layer is plated on the ceramic adapter block 430. Signal pads and ground pads are provided on the metal layer of the ceramic adapter block 430 on the inside of the housing, and signal pads and ground pads are also provided on the metal layer of the ceramic adapter block 430 on the outside of the housing. The signal pads on the inside and outside of the ceramic adapter block 430 are connected to achieve electrical connection between the inside and outside of the ceramic adapter block 430, thereby realizing the conversion of electrical signals, working signals, etc. through the ceramic adapter block 430.

[0057] Figure 8 This is a schematic diagram illustrating the assembly of a ceramic adapter block 430 and a flexible circuit board in an optical module according to an embodiment of this application. Figure 9 This is an exploded view of a ceramic adapter block 430 and a flexible circuit board in an optical module provided in an embodiment of this application. A boss 4310 is provided on one end of the ceramic adapter block 430 facing the circuit board 300 (the end located outside the hermetic housing). The boss 4310 is integrally formed with the ceramic adapter block 430 and is connected to the flexible circuit board. The flexible circuit board transmits signals from the circuit board 300 to the ceramic adapter block 430, which then transfers the signals to the laser assembly 440, enabling the normal operation of the laser and other components in the laser assembly 440.

[0058] The ceramic adapter block 430 is inserted into the side of the airtight housing and has multiple mounting slots 4320. The multiple mounting slots 4320 are arranged in a stepped manner, and each mounting slot 4320 is provided with a solder pad. The laser driver, laser, etc. of the laser assembly 440 are connected to the solder pads on the mounting slot 4320 through gold wires to realize signal conversion.

[0059] The boss 4310 on one side of the ceramic adapter block 430 can be connected to the circuit board 300 through two flexible circuit boards. That is, the upper side of the boss 4310 is connected to the first flexible circuit board 600, and the lower side of the boss 4310 is connected to the second flexible circuit board 700, so as to realize the transmission of various signals.

[0060] To achieve the connection between the ceramic adapter block 430 and the flexible circuit board, signal pads and ground pads are arranged side by side on the side of the boss 4310. FPC signal pads and FPC ground pads are correspondingly arranged at one end of the flexible circuit board. The signal pads on the ceramic adapter block 430 are connected to the corresponding FPC signal pads on the flexible circuit board by soldering, and the ground pads on the ceramic adapter block 430 are connected to the corresponding PC ground pads on the flexible circuit board by soldering, thereby achieving the connection and fixation between the flexible circuit board and the ceramic adapter block 430.

[0061] In this embodiment, the front-to-back length of the boss 4310 is the same as that of the ceramic adapter block 430, so as to leave sufficient space on the side of the boss 4310 to set up signal pads and ground pads, ensuring the integrity of signal transmission between the ceramic adapter block 430 and the flexible circuit board. Furthermore, the upper side of the boss 4310 is a certain distance from the upper side of the ceramic adapter block 430, and the lower side of the boss 4310 is also a certain distance from the lower side of the ceramic adapter block 430, to facilitate the soldering of the upper and lower sides of the boss 4310 to the flexible circuit board.

[0062] Figure 10 This is a schematic diagram of the structure of a ceramic adapter block 430 in an optical module provided in an embodiment of this application. Figure 11 This is a schematic diagram of another angle of the ceramic adapter block 430 in an optical module provided in an embodiment of this application. Figure 12 This is a partial structural diagram of a ceramic adapter block 430 in an optical module provided in an embodiment of this application. Figure 10 , Figure 11 , Figure 12 As shown, in high-speed products, the transmission mode of high-speed signals is GND-Signal-GND mode. Therefore, the pad mode for interconnecting the ceramic adapter block 430 and the flexible circuit board is GSG mode. That is, the signal pad and ground pad structure on the side of the boss 4310 of the ceramic adapter block 430 is a first ground pad 4311, a signal pad 4312 and a second ground pad 4313. The signal pad 4312 is located between the first ground pad 4311 and the second ground pad 4313.

[0063] When the first grounding pad 4311, signal pad 4312, and second grounding pad 4313 on the boss 4310 are connected to the pads on the flexible circuit board, they need to be connected by solder. The width of the pads must be a certain size to ensure successful soldering. This will inevitably lead to impedance discontinuities at the solder joints of the first grounding pad 4311, signal pad 4312, and second grounding pad 4313 on the boss 4310 and the pads on the flexible circuit board, resulting in changes in signal quality and deterioration in signal integrity.

[0064] The impedance at the solder joint between the signal pads and ground pads on the ceramic adapter block 430 and the pads on the flexible circuit board is related to the dielectric constant of the ceramic adapter block 430 itself. When the dielectric constant is smaller, the impedance will increase if other parameters remain unchanged. Therefore, this application can increase the impedance by reducing the dielectric constant of the ceramic adapter block 430, thereby reducing the impedance discontinuities at the solder joint between the ceramic adapter block 430 and the pads on the flexible circuit board.

[0065] In this embodiment, to improve signal quality, reduce impedance discontinuities, and enhance high-frequency performance, an isolation groove is provided between the signal pad and the ground pad of the boss 4310. This isolation groove is recessed into the signal pad and the ground pad. By providing an isolation groove on the boss 4310, the dielectric constant of the ceramic adapter block 430 is reduced. There is no conductive medium inside the isolation groove. The lower dielectric constant of the isolation groove reduces the dielectric constant of the medium surrounding the isolation groove, thereby increasing the impedance of the signal pad and the ground pad around the isolation groove.

[0066] Specifically, a first isolation groove 4314 is provided between the first grounding pad 4311 and the signal pad 4312, and a second isolation groove 4315 is provided between the signal pad 4312 and the second grounding pad 4313. Both the first isolation groove 4314 and the second isolation groove 4315 are recessed in the first grounding pad 4311, the signal pad 4312 and the second grounding pad 4313, and extend from the left side of the boss 4310 to the right side.

[0067] When a first isolation groove 4314 is provided between the first ground pad 4311 and the signal pad 4312 of the boss 4310, and a second isolation groove 4315 is provided between the signal pad 4312 and the second ground pad 4313, the first isolation groove 4314 and the second isolation groove 4315 extend from the outer wall of the ceramic adapter block 430 in the left-right direction to the side of the boss 4310 facing the circuit board 300. That is, the length of the first isolation groove 4314 and the second isolation groove 4315 in the left-right direction is the same as the length of the signal pad and the ground pad on the boss 4310 in the left-right direction.

[0068] In addition, when a first isolation groove 4314 is provided between the first ground pad 4311 and the signal pad 4312 of the boss 4310, and a second isolation groove 4315 is provided between the signal pad 4312 and the second ground pad 4313, the first isolation groove 4314 extends from the front side of the first ground pad 4311 to the rear side of the signal pad 4312, and the second isolation groove 4315 extends from the front side of the signal pad 4312 to the rear side of the second ground pad 4313. That is, the width dimension of the first isolation groove 4314 in the front-back direction can be equal to the distance between the first ground pad 4311 and the signal pad 4312, and the width dimension of the second isolation groove 4315 in the front-back direction can be equal to the distance between the signal pad 4312 and the second ground pad 4313.

[0069] In this embodiment, the width of the first isolation groove 4314 in the front-to-back direction can also be smaller than the distance between the first ground pad 4311 and the signal pad 4312, and the width of the second isolation groove 4315 in the front-to-back direction can also be smaller than the distance between the signal pad 4312 and the second ground pad 4313. As long as the boss 4310 of the ceramic adapter block 430 has an isolation groove between the signal pad and the ground pad, the size limitation of the isolation groove in this application can be set according to the actual situation.

[0070] In this embodiment, an isolation groove can be provided only between the signal pad and the ground pad on one side of the boss 4310. The side with the isolation groove transmits high-speed signals, while the side without the isolation groove transmits low-speed signals. For example, an isolation groove can be provided between the signal pad and the ground pad on the upper side of the boss 4310; alternatively, isolation grooves can be provided between the signal pads and the ground pads on both opposite sides of the boss 4310. That is, the upper side of the boss 4310 is provided with a first ground pad, a first signal pad, and a second ground pad. The first signal pad is located between the first ground pad and the second ground pad. The pads on the first flexible circuit board 600 are soldered together with the first ground pad, the first signal pad, and the second ground pad on the upper side of the boss 4310 to connect the first flexible circuit board 600 to the upper side of the boss 4310.

[0071] The lower side of the boss 4310 is provided with a third ground pad, a second signal pad and a fourth ground pad. The second signal pad is located between the third ground pad and the fourth ground pad. The pads on the second flexible circuit board 700 are soldered together with the third ground pad, the second signal pad and the fourth ground pad on the lower side of the boss 4310 to connect the second flexible circuit board 700 to the lower side of the boss 4310.

[0072] On the upper side of the boss 4310, a first isolation groove is provided between the first ground pad and the first signal pad, and a second isolation groove is provided between the first signal pad and the second ground pad; on the lower side of the boss 4310, a third isolation groove is provided between the third ground pad and the second signal pad, and a fourth isolation groove is provided between the second signal pad and the fourth ground pad.

[0073] In this embodiment, when the flexible circuit board is connected to the ceramic adapter block 430, the flexible circuit board covers the isolation grooves provided on the ceramic adapter block 430. That is, when the first isolation groove 4314 and the second isolation groove 4315 are provided on the upper side of the boss 4310 of the ceramic adapter block 430, when the flexible circuit board is soldered to the boss 4310 of the ceramic adapter block 430, the flexible circuit board covers the first grounding pad 4311, the first isolation groove 4314, the signal pad 4312, the second isolation groove 4315, and the second grounding pad 4313 on the boss 4310.

[0074] The first, second, third, and fourth isolation grooves provided on the upper and lower sides of the boss 4310 reduce the dielectric constant of the ceramic adapter block 430, thereby increasing the impedance at the connection between the ground pad, signal pad, and flexible circuit board pad on the ceramic adapter block 430. This reduces impedance discontinuities at the welding points between the ceramic adapter block 430 and the flexible circuit board pad, saving space, ensuring the width of the pads, ensuring stable welding process, and most importantly, optimizing signal quality and ensuring the integrity of signal transmission.

[0075] The optical module provided in this application includes a circuit board, an optical emitting sub-module, and a flexible circuit board. The optical emitting sub-module includes a housing and a ceramic adapter block coated with a metal layer. One side of the housing has an opening, and one side of the ceramic adapter block is inserted into the housing through the opening, while the other side is exposed outside the housing. The housing and the ceramic adapter block form an hermetically sealed housing to house optical components such as the laser assembly, lens array, wavelength division multiplexing assembly, and lens assembly of the optical emitting sub-module. One end of the ceramic adapter block inside the hermetically sealed housing is connected to the laser assembly via a gold wire, and the other end outside the hermetically sealed housing has a boss. Signal pads and ground pads are arranged side-by-side on the metal layer on the side of the boss. One end of the flexible circuit board is connected to the ceramic adapter block through the signal pads and ground pads on the boss. One end connects to the circuit board, and the working signals generated on the circuit board are transferred to the laser assembly via the flexible circuit board and ceramic adapter block to drive the laser assembly to generate a laser beam and achieve light emission. An isolation groove is provided between the signal pads and ground pads on the protruding side of the ceramic adapter block. The isolation groove is recessed within the signal pads and ground pads, and there is no conductive medium inside the isolation groove, resulting in a low dielectric constant. This lower dielectric constant reduces the dielectric constant of the surrounding medium, increasing the impedance of the signal pads and ground pads around the isolation groove. This reduces impedance discontinuities at the solder joints of the signal pads, ground pads, and flexible circuit board pads on the ceramic adapter block, thereby improving the signal transmission quality between the ceramic adapter block and the flexible circuit board and ensuring signal transmission integrity. Furthermore, the isolation groove is located on the metal layer of the ceramic adapter block exposed on the outside of the housing, without affecting the hermetic packaging of the light emission sub-module.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An optical module, characterized in that, include: Circuit board; A light-emitting submodule includes a housing and a ceramic adapter block coated with a metal layer. One side of the housing has an opening, through which one side of the ceramic adapter block is inserted into the housing, while the other side remains exposed outside the housing, forming an airtight enclosure. A laser assembly is housed within the housing. The side of the ceramic adapter block inserted into the housing has multiple mounting slots arranged in a stepped pattern. Pads are provided on each mounting slot, and the laser assembly connects to these pads. On the metal layer outside the housing, the ceramic adapter block has signal pads, a first ground pad, and a second ground pad arranged side-by-side. Two grounding pads are provided, and the signal pad is disposed between the first grounding pad and the second grounding pad. The pads on the mounting groove are connected to the signal pads. A first isolation groove is provided between the first grounding pad and the signal pad, and a second isolation groove is provided between the signal pad and the second grounding pad. The first isolation groove and the second isolation groove extend from the outer wall of the ceramic adapter block toward the circuit board, and the first isolation groove and the second isolation groove are recessed into the signal pad and the grounding pad. There is no conductive medium in the first isolation groove and the second isolation groove to reduce the dielectric constant of the ceramic adapter block. The flexible circuit board has one end connected to the ceramic adapter block via the signal pad, the first ground pad, and the second ground pad, and the other end connected to the circuit board. The flexible circuit board covers the first isolation groove and the second isolation groove.

2. The optical module according to claim 1, characterized in that, The ceramic adapter block has a boss exposed on the outside of the housing, and the boss is integrally formed with the ceramic adapter block; the signal pad and the ground pad are provided on the side where the boss connects to the ceramic adapter block.

3. The optical module according to claim 2, characterized in that, The signal pad and the grounding pad are disposed on the side where the boss connects to the outer wall of the ceramic adapter block, and the signal pad and the grounding pad are disposed adjacent to each other.

4. The optical module according to claim 3, characterized in that, Both the first isolation groove and the second isolation groove extend from one side of the boss to the other side.

5. The optical module according to claim 3, characterized in that, The front-to-back dimension of the first isolation groove is equal to the distance between the first grounding pad and the signal pad.

6. The optical module according to claim 3, characterized in that, The front-to-back dimension of the first isolation groove is smaller than the distance between the first ground pad and the signal pad.

7. The optical module according to claim 3, characterized in that, The front-to-back length of the boss is the same as the front-to-back length of the ceramic adapter block.

8. The optical module according to claim 2, characterized in that, There is a certain distance between the boss and the two opposite sides of the ceramic adapter block.

9. The optical module according to claim 1, characterized in that, The optical emission sub-module includes a laser assembly, which is placed inside the housing; the ceramic adapter block has a mounting groove at one end inserted into the housing, and a solder pad is provided on the mounting groove, and the laser assembly is connected to the solder pad via gold wire.

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