An optical module

Abstract

The optical module provided by the present application includes a lower shell, an upper shell covering the lower shell, a light emitting submodule and a circuit board. The light emitting submodule is arranged in a receiving cavity formed by the upper shell and the lower shell, and includes a laser chip for generating a light beam to realize light emission; a gold finger and a laser driver chip are arranged on the circuit board, the laser driver chip is connected to the gold finger through a high-speed signal line, and the gold finger is used to be electrically connected to an external electrical connector; the laser driver chip is signal-connected to the laser chip; the width dimension of the connection between the gold finger and the high-speed signal line is smaller than the width dimension of the connection between the gold finger and the external part. The present application performs a local narrowing process on the width of the gold finger, so that the width of the connection between the gold finger and the high-speed signal line is narrowed, the difference between the line width of the gold finger and the line width of the high-speed signal line is reduced, the characteristic impedance of the connection between the gold finger and the high-speed signal line is reduced, the impedance discontinuity point of the gold finger is optimized, and the high-frequency performance of the circuit board is improved.

Description

Technical Field

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

[0002] With the development of new services and application models such as cloud computing, mobile Internet, and video, the development and progress of optical communication technology has become increasingly important. In optical communication technology, optical modules are tools for realizing the mutual conversion of optical and electrical signals, and are one of the key components in optical communication equipment. In addition, with the development of optical communication technology, the transmission rate of optical modules is constantly increasing.

[0003] The circuit board in the optical module is the carrier of various optoelectronic components. The gold finger is an electrical interface on the circuit board. It looks like a pad arranged like a finger. It is used as the import and export of the circuit board to connect to the external network through plugging and unplugging with the host computer connector. In the field of high-speed optical modules, the gold finger is an important channel connecting the circuit board with external signals. For optical modules with different packaging forms, the design of the gold finger needs to meet the corresponding protocol requirements.

[0004] However, the line width of the gold finger required by the protocol is usually much larger than the line width of the high-speed signal line on the circuit board, resulting in low impedance at the gold finger, introducing impedance discontinuities, degrading the signal integrity of the system, increasing reflection losses, and affecting the high-frequency performance of the circuit board. Summary of the invention

[0005] The embodiment of the present application provides an optical module to solve the problem that the impedance at the gold finger on the circuit board in the current optical module is discontinuous, which affects the high-frequency performance of the circuit board.

[0006] The present application provides an optical module, comprising:

[0007] Lower housing;

[0008] An upper shell, covering the lower shell, and forming a containing cavity with the lower shell;

[0009] The light emission submodule is disposed in the accommodating cavity and includes a laser chip for generating a light beam to realize light emission;

[0010] A circuit board is provided with a gold finger and a laser driver chip, wherein the laser driver chip is connected to the gold finger through a high-speed signal line, and the gold finger is used to be electrically connected to an external electrical connector; the laser driver chip is signal-connected to the laser chip; the width dimension of the connection between the gold finger and the high-speed signal line is smaller than the width dimension of the connection between the gold finger and the outside, so as to optimize the impedance discontinuity point at the connection between the gold finger and the high-speed signal line.

[0011] The optical module provided by the present application includes a lower shell, an upper shell covering the lower shell, a light emitting submodule and a circuit board, the upper shell and the lower shell form a containing cavity, the light emitting submodule is arranged in the containing cavity, and the light emitting submodule includes a laser chip for generating a light beam to realize light emission; a gold finger and a laser driver chip are arranged on the circuit board, the laser driver chip is connected to the gold finger through a high-speed signal line, and the gold finger is used to be electrically connected to an external electrical connector; the laser driver chip is connected to the laser chip signal; the width dimension of the connection between the gold finger and the high-speed signal line is smaller than the width dimension of the external connection of the gold finger, which is used to optimize the impedance discontinuity point at the connection between the gold finger and the high-speed signal line. On the basis of ensuring the requirements of the gold finger protocol, the present application locally narrows the width of the gold finger, so that the width of the connection between the gold finger and the high-speed signal line is narrowed, and the difference between the line width of the gold finger and the line width of the high-speed signal line is reduced, thereby reducing the characteristic impedance at the connection between the gold finger and the high-speed signal line, optimizing the impedance discontinuity point at the connection between the gold finger and the high-speed signal line, making the signal integrity at the gold finger better, and thus improving the high-frequency performance of the circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 It is a schematic diagram of the connection relationship of optical communication terminals;

[0014] Figure 2 is a schematic diagram of the structure of an optical network unit;

[0015] Figure 3 A schematic diagram of the structure of an optical module provided in an embodiment of the present application;

[0016] Figure 4 A schematic diagram of the decomposed structure of an optical module provided in an embodiment of the present application;

[0017] Figure 5 This is a schematic diagram of the structure of the gold finger on the circuit board in a typical optical module;

[0018] Figure 6 This is a top view of the gold fingers on the circuit board in a typical optical module.

[0019] Figure 7 This is a schematic diagram of the TDR test results of the current circuit board;

[0020] Figure 8A schematic diagram of the structure of a gold finger on a circuit board in an optical module provided in an embodiment of the present application;

[0021] Fig. 9 A top view of a gold finger on a circuit board in an optical module provided in an embodiment of the present application;

[0022] Fig.10 A partially enlarged schematic diagram of a gold finger on a circuit board in an optical module provided in an embodiment of the present application;

[0023] Fig.11 A schematic diagram of TDR simulation results of a circuit board in an optical module provided in an embodiment of the present application;

[0024] Fig.12 A schematic diagram of the reflection loss simulation results of a circuit board in an optical module provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] One of the core links of fiber-optic communication is the conversion between optical and electrical signals. Fiber-optic communication uses optical signals carrying information to transmit in optical fiber / optical waveguide and other information transmission equipment. The passive transmission characteristics of light in optical fiber / optical waveguide can achieve low-cost and low-loss information transmission; while information processing equipment such as computers use electrical signals. In order to establish an information connection between information transmission equipment such as optical fiber / optical waveguide and information processing equipment such as computers, it is necessary to achieve the conversion between electrical and optical signals.

[0027] Optical modules realize the above-mentioned mutual conversion function of optical and electrical signals in the field of optical fiber communication technology. The mutual conversion of optical signals and electrical signals is the core function of optical modules. Optical modules realize electrical connection with external host computers through the gold fingers on their internal circuit boards. The main electrical connections include power supply, I2C signals, data signals and grounding. The electrical connection method realized by gold fingers has become the mainstream connection method in the optical module industry. Based on this, the definition of the pins on the gold fingers has formed a variety of industry protocols / specifications.

[0028] Figure 1 Figure 1 is a schematic diagram of the connection relationship of optical communication terminals. 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;

[0029] 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; and 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.

[0030] The optical port of the optical module 200 is connected to the optical fiber 101 to establish 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 to establish a bidirectional electrical signal connection with the optical network terminal 100; the mutual conversion between the optical signal and the electrical signal is realized inside the optical module, so as to establish 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 input into the optical fiber.

[0031] The optical network terminal has an optical module interface 102, which is used to access the optical module 200 and establish a bidirectional electrical signal connection with the optical module 200; the optical network terminal has a network cable interface 104, which is used to access the network cable 103 and establish 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 the signal from the optical module to the network cable, and transmits the signal from the network cable to the optical module. The optical network terminal acts as a host computer of the optical module to monitor the operation of the optical module.

[0032] At this point, the remote server establishes a two-way signal transmission channel with the local information processing device through optical fiber, optical module, optical network terminal and network cable.

[0033] Common information processing equipment includes routers, switches, and electronic computers. The optical network terminal is the host computer of the optical module, which provides data signals to the optical module and receives data signals from the optical module. Other common optical module host computers include optical line terminals.

[0034] Figure 2 Figure 1 is a schematic diagram of the optical network terminal structure. Figure 2 As shown, the optical network terminal 100 has a circuit board 105, and a cage 106 is arranged on the surface of the circuit board 105; an electrical connector is arranged inside the cage 106 for connecting to the electrical port of the optical module such as the gold finger; a heat sink 107 is arranged on the cage 106, and the heat sink 107 has protrusions such as fins to increase the heat dissipation area.

[0035] 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 .

[0036] The cage 106 is located on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged inside the cage; the optical module is inserted into the cage, and the cage fixes the optical module, 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.

[0037] Figure 3 A schematic diagram of an optical module structure provided in an embodiment of the present application is provided. Figure 4 A schematic diagram of the optical module decomposition structure is provided for the embodiment of the present application. Figure 3 , Figure 4 As shown, the optical module 200 provided in the embodiment of the present application 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 .

[0038] The upper shell 201 is covered on the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity is generally a square body. Specifically, the lower shell includes a main board and two side panels located on both sides of the main board and perpendicular to the main board; the upper shell includes a third shell, and the third shell is covered on the two side panels of the upper shell to form a wrapping cavity; the upper shell may also include two side walls located on both sides of the third shell and perpendicular to the third shell, and the two side walls are combined with the two side panels to realize the upper shell covering the lower shell.

[0039] The two openings can specifically be two end openings (204, 205) in the same direction, or two openings in different directions; one of the openings is an electrical port 204, and the gold finger of the circuit board extends from the electrical port 204 and is inserted into a host computer such as an optical network terminal; the other opening is an optical port 205, which is used for external optical fiber access to connect the optical transmitting submodule 400 and the optical receiving submodule 500 inside the optical module; optoelectronic devices such as the circuit board 300, the optical transmitting submodule 400 and the optical receiving submodule 500 are located in the encapsulating cavity.

[0040] The upper shell and the lower shell are combined to facilitate installation of components such as the circuit board 300, the optical transmitting submodule 400, the optical receiving submodule 500 into the shell. The upper shell and the lower shell form the outermost packaging protection shell of the optical module. The upper shell and the lower shell are generally made of metal materials, which is conducive to electromagnetic shielding and heat dissipation. The shell of the optical module is generally not made into an integrated component. In this way, when assembling components such as circuit boards, positioning components, heat dissipation and electromagnetic shielding components cannot be installed, which is not conducive to production automation.

[0041] The unlocking component 203 is located on the outer wall of the cavity / lower shell 202 and is used to achieve a fixed connection between the optical module and the host computer, or to release the fixed connection between the optical module and the host computer.

[0042] The unlocking component 203 has a locking component that matches the cage of the host computer; pulling the end of the unlocking component can make the unlocking component move relatively on the surface of the outer wall; the optical module is inserted into the cage of the host computer, and the locking component of the unlocking component fixes the optical module in the cage of the host computer; 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, so that the optical module can be pulled out of the cage of the host computer.

[0043] The circuit board 300 is provided with circuit traces, electronic components (such as capacitors, resistors, transistors, MOS tubes) and chips (such as MCU, laser driver chip, limiting amplifier chip, clock data recovery CDR, power management chip, data processing chip DSP), etc.

[0044] The circuit board connects the electrical components in the optical module according to the circuit design through circuit routing to achieve electrical functions such as power supply, electrical signal transmission and grounding.

[0045] The chip on the circuit board 300 can be a multi-functional integrated chip, such as integrating the laser driver chip and the MCU chip into one chip, or integrating the laser driver chip, the limiting amplifier chip and the MCU into one chip. The chip is an integration of circuits, but the functions of each circuit do not disappear due to the integration, but the circuit presentation form changes, and the chip still has the circuit form. Therefore, when three independent chips, MCU, laser driver chip and limiting amplifier chip, are set on the circuit board, this is equivalent to setting a single chip with three functions in one on the circuit board 300.

[0046] Circuit boards are generally rigid circuit boards. Rigid circuit boards can also perform load-bearing functions due to their relatively hard material. For example, rigid circuit boards can stably carry chips. When optical transceivers are located on the circuit boards, rigid circuit boards can also provide stable load-bearing. Rigid circuit boards can also be inserted into electrical connectors in the cage of the host computer. Specifically, metal pins / gold fingers are formed on the end surface of one side of the rigid circuit board for connecting to the electrical connector. These are not easy to achieve with flexible circuit boards.

[0047] 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. For example, flexible circuit boards can be used to connect rigid circuit boards to optical transceiver devices.

[0048] In the embodiment of the present application, the gold finger 310 is arranged on a side of the circuit board 300 away from the optical transmission sub-module 400. The gold finger 310 is an electrical interface on the circuit board 300, and the plugging and unplugging of the gold finger 310 and the electrical connector in the optical network terminal 100 serves as the import and export of the circuit board 300 connected to the external network.

[0049] The external electrical connector is generally a spring-type connector array, and the springs of the electrical connector are electrically connected to the pins of the gold finger 310, thereby realizing the electrical connection between the electrical connector and the gold finger 310. In order to facilitate the connection between the spring and the gold finger pin, the spring of the electrical connector is generally wider. Considering the width of the spring and the spacing between adjacent springs, the width of the gold finger 310 on the circuit board 300 should be equal to or slightly smaller than the width of the spring, which results in a wider line width of the gold finger 310.

[0050] In the field of high-speed optical modules, for optical modules with different packaging forms, the design of gold fingers needs to meet the corresponding protocol requirements. However, the gold finger line width required by the protocol is usually much larger than the line width of the high-speed signal line on the circuit board, resulting in low impedance at the gold finger, introducing impedance discontinuities, degrading the signal integrity of the system, increasing reflection losses, and affecting the high-frequency performance of the circuit board.

[0051] The transmission characteristic impedance of high-speed signal lines can be expressed by the inductance per unit length L and the capacitance per unit length C, that is:

[0052]

[0053] The factors that affect the characteristic impedance are mainly line width, dielectric thickness, dielectric constant and copper foil thickness. For circuit boards with a certain material, the dielectric constant and copper foil thickness remain basically unchanged, and the line width and dielectric thickness can be adjusted through design. Among them, the line width will affect the inductance per unit length L, and then affect the characteristic impedance. The inductance can be approximately expressed as:

[0054]

[0055] Where l is the length of the trace, w is the line width, and t is the thickness of the copper foil. According to formula (2), it can be concluded that the larger the line width, the smaller the inductance. On the other hand, the change in line width will also affect the capacitance per unit length. The larger the line width, the more the electric lines between the trace and the plane are concentrated in the dielectric area, and the larger the capacitance per unit length. In summary, combined with formula (1), it can be concluded that the larger the line width, the smaller the inductance per unit length, the larger the capacitance per unit length, and the smaller the characteristic impedance; conversely, the larger the characteristic impedance.

[0056] In addition, the dielectric thickness will also affect the characteristic impedance. When the dielectric thickness increases, it means that the conductor spacing increases, and the inductance per unit length increases. At the same time, according to the characteristics of the flat plate capacitor, the increase in spacing will lead to a decrease in capacitance. Therefore, it can be concluded from formula (1) that the increase in dielectric thickness will ultimately lead to an increase in characteristic impedance.

[0057] Figure 5 This is a schematic diagram of the structure of the gold finger on the circuit board in a typical optical module. Figure 6This is a top view of the gold fingers on the circuit board in a typical optical module. Figure 5 , Figure 6 As shown, a gold finger 310 and a laser driver chip are provided on the circuit board 300. The laser driver chip on the circuit board 300 is connected to the gold finger 310 through a high-speed signal line 320, thereby realizing the connection between the circuit board 300 and the external network through the gold finger 310; the laser driver chip is connected to the laser chip signal of the optical emission submodule 400. In this way, the circuit board 300 provides an electrical signal to the laser driver chip through the gold finger 310. After receiving the electrical signal, the laser driver chip generates a laser drive signal and transmits the laser drive signal to the laser chip. The laser chip generates a light beam through the laser drive signal to realize light emission.

[0058] Similarly, a light receiving driver chip is also provided on the circuit board 300, and the light receiving chip of the light receiving submodule 500 is connected to the light receiving driver chip signal, and the light receiving driver chip is connected to the gold finger 310 through a high-speed signal line. In this way, the circuit board 300 provides an electrical signal to the light receiving driver chip through the gold finger 310, and the light receiving driver chip generates a light receiving drive signal after receiving the electrical signal, and transmits the light receiving driver chip to the light receiving chip, and the light receiving chip performs photoelectric conversion through the light receiving driver chip, and transmits the converted electrical signal to the optical network terminal 100 through the gold finger, thereby realizing light reception.

[0059] It can be clearly seen that the width of the gold finger 310 is much larger than the width of the high-speed signal line 320. Therefore, according to the above theory, if the gold finger 310 is not processed, the larger line width at the gold finger 310 will cause its characteristic impedance to be much lower than the characteristic impedance at the high-speed signal line 320, thereby causing impedance discontinuity, thereby affecting the high-speed signal transmission performance on the circuit board 300.

[0060] The commonly used gold finger design currently adopts the solution of hollowing out the reference layer under the gold finger, increasing the characteristic impedance of the gold finger by increasing the dielectric thickness, reducing the impedance discontinuity, and thus improving the high-frequency performance. However, due to the limitation of the gold finger width on the standard protocol, the above solution has very limited ability to optimize the impedance discontinuity.

[0061] Figure 7 The following is a schematic diagram of the TDR test results of a typical circuit board. Figure 7 As shown in the figure, the part marked by the oval is the impedance of the gold finger when the reference surface is completely hollowed out, which is about 83Ω, which is still far from the ideal 100Ω. Therefore, it is necessary to optimize the impedance design of the gold finger.

[0062] Figure 8 This is a schematic diagram of the structure of a gold finger 310 on a circuit board 300 in an optical module provided in an embodiment of the present application. Fig. 9FIG. 1 is a top view of a gold finger 310 on a circuit board 300 in an optical module provided in an embodiment of the present application. Figure 8 , Fig. 9 As shown, in the optical module provided by the present application, on the basis of ensuring the requirements of the gold finger design protocol, the width of the gold finger 310 is locally narrowed. Combining formula (1) and formula (2), it can be seen that the smaller the line width of the gold finger 310, the larger the inductance per unit length, and the smaller the capacitance per unit length. In this way, the characteristic impedance at the gold finger 310 is larger, and the impedance optimization at the gold finger 310 on the circuit board 300 is achieved, so that the signal integrity at the gold finger 310 is better.

[0063] Specifically, the present application ensures that the width of the gold finger body still meets the protocol requirements, and narrows the width of the connection between the gold finger 310 and the high-speed signal line 320, so that the width of the connection between the gold finger 310 and the high-speed signal line 320 is smaller than the width of the external connection of the gold finger 310, thereby narrowing the line width difference between the gold finger 310 and the high-speed signal line 320, improving the characteristic impedance of the connection between the gold finger 310 and the high-speed signal line 320, and optimizing the impedance discontinuity point at the gold finger 310.

[0064] At the same time, the width of the connection between the gold finger 310 and the electrical connector is consistent with the gold finger protocol requirements, so as to ensure that the width of the portion where the gold finger 310 contacts the electrical connector meets the standard protocol requirements.

[0065] Fig.10 This is a partially enlarged schematic diagram of the gold finger 310 in the optical module provided in the embodiment of the present application. Fig.10 As shown, the gold finger 310 includes a first connection part 3101 and a second connection part 3102. The first connection part 3101 faces the high-speed signal line 320 and is connected to the high-speed signal line 320; the second connection part 3102 faces the electrical connector and is connected to the electrical connector, thereby realizing signal transmission between the circuit board and the optical network terminal. In the embodiment of the present application, the width of the first connection part 3101 is smaller than the width of the second connection part 3102, thereby reducing the line width difference between the first connection part 3101 of the gold finger 310 and the high-speed signal line 320. According to formula (1) and formula (2), the characteristic impedance at the gold finger 310 is increased, and the impedance discontinuity point between the high-speed signal line 320 and the first connection part 3101 is reduced.

[0066] In the embodiment of the present application, in order to optimize the characteristic impedance at the first connection portion 3101 and make the impedance from the high-speed signal line 320 to the first connection portion 3101 continuous, the widths of the upper and lower ends of the first connection portion 3101 (the direction toward the high-speed signal line 320 is the upper end of the first connection portion 3101, and the direction away from the high-speed signal line 320 is the lower end of the first connection portion 3101) are not the same. Specifically, the width from the connection between the first connection portion 3101 and the high-speed signal line 320 to the connection between the first connection portion 3101 and the second connection portion 3102 gradually increases, that is, the width of the first connection portion 3101 gradually increases along the up and down directions, the width dimension at the connection between the first connection portion 3101 and the high-speed signal line 320 is the smallest, and the width dimension at the connection between the first connection portion 3101 and the second connection portion 3102 is the largest, so that the first connection portion 3101 is trapezoidal from top to bottom.

[0067] In order to make the width of the first connection part 3101 smaller than the width of the second connection part 3102, the present application keeps the width of the second connection part 3102 consistent with the protocol requirements, with the aim of ensuring that the width of the portion where the gold finger 310 contacts the electrical connector meets the standard protocol requirements, while the width of the first connection part 3101 is shortened compared to the second connection part 3102, thereby narrowing the width of the first connection part 3101.

[0068] In the embodiment of the present application, the width of the first connection portion 3101 is shortened by 4 mils compared with the second connection portion 3102. The narrowing method is that the first connection portion 3101 of a single gold finger 310 is shortened by 2 mils on both sides, so that both side edges of the first connection portion 3101 are close to the central axis of the gold finger 310.

[0069] When the two sides of the first connection part 3101 approach the central axis of the gold finger 310 , the two opposite sides of the second connection part 3102 protrude from the two opposite sides of the first connection part 3101 , that is, one side of the second connection part 3102 protrudes 2 mils compared with one side of the first connection part 3101 .

[0070] In the embodiment of the present application, a chamfer is provided at the connection between the side of the second connection part 3102 protruding from the first connection part 3101 and the side of the first connection part 3101, that is, the protruding part of the second connection part 3102 is chamfered so that the protruding part of the second connection part 3102 is smoother.

[0071] In the embodiment of the present application, the gold finger 310 also includes a third connection part 3103, the third connection part 3103 faces away from the first connection part 3101, and the third connection part 3103 is connected to the second connection part 3102. That is, the gold finger 310 is divided from top to bottom into a first connection part 3101, a second connection part 3102 and a third connection part 3103, the first connection part 3101 is connected to the high-speed signal line 320, one end of the second connection part 3102 is connected to the first connection part 3101, and the other end is connected to the third connection part 3103, and the second connection part 3102 is connected to the electrical connector of the optical network terminal. The high-speed signal transmitted by the high-speed signal line 320 is transmitted to the first connection part 3101 of the gold finger 310, and the high-speed signal is transmitted to the second connection part 3102 through the first connection part 3101, and the high-speed signal is transmitted to the electrical connector of the optical network terminal through the second connection part 3102, so as to realize the high-speed signal transmission between the high-speed signal line 320, the gold finger 310 and the optical network terminal.

[0072] The width dimension of the third connection part 3103 may be the same as the width dimension of the second connection part 3102, that is, the third connection part 3103 is not narrowed; the width dimension of the third connection part 3103 may also be smaller than the width dimension of the second connection part 3102, that is, the third connection part 3103 is narrowed.

[0073] When the third connection portion 3103 is narrowed, the two opposite sides of the second connection portion 3102 protrude from the two opposite sides of the third connection portion 3103, and a chamfer is provided at the connection between the side of the second connection portion 3102 protruding from the third connection portion 3103 and the side of the third connection portion 3103.

[0074] In the embodiment of the present application, when the gold finger 310 is divided into a first connection part 3101, a second connection part 3102 and a third connection part 3103 from top to bottom, the second connection part 3102 is located at the middle 1 / 3 of the gold finger 310 to facilitate the connection between the gold finger 310 and the electrical connector of the optical network terminal.

[0075] The optimization design idea adopted by the gold finger 310 in the present application is based on ensuring the protocol requirements, and the width of the gold finger 310 is locally narrowed, that is, the line width of the gold finger 310 is reduced. Combining formula (1) and formula (2), the unit length inductance of the gold finger 310 is reduced, the unit length capacitance is reduced, and the characteristic impedance at the gold finger 310 is increased, thereby optimizing the impedance discontinuity point at the connection between the high-speed signal line 320 and the gold finger 310, so that the signal integrity at the gold finger is better.

[0076] Fig.11 This is a schematic diagram of the TDR simulation results of the gold finger in the optical module provided in the embodiment of the present application. Fig.11As shown, m1 is the TDR simulation result of the gold finger after optimization in this application, and m2 is the TDR simulation result of the gold finger before optimization. As shown in m1 and m2, after the width of the gold finger is locally narrowed in this application, the impedance at the gold finger 310 is increased by about 8Ω, which is closer to the ideal 100Ω.

[0077] Fig.12 This is a schematic diagram of the simulation results of the reflection loss of the gold finger in the optical module provided in the embodiment of the present application. Fig.12 As shown, m1 is the reflection loss simulation result of the gold finger after optimization in this application, and m2 is the reflection loss simulation result of the gold finger before optimization. As shown in m1 and m2, after the width of the gold finger is locally narrowed in this application, the reflection loss of the gold finger after optimization is optimized by about 3dB compared with the gold finger before optimization.

[0078] The optical module provided in the embodiment of the present application includes a lower shell, an upper shell covering the lower shell, an optical emission submodule and a circuit board, the upper shell and the lower shell form a housing cavity, the optical emission submodule is arranged in the housing cavity, and the optical emission submodule includes a laser chip for generating a light beam to realize light emission; a gold finger and a laser driver chip are arranged on the circuit board, the laser driver chip is connected to the gold finger through a high-speed signal line, and the gold finger is used to be electrically connected to an external electrical connector; the laser driver chip is connected to the laser chip signal; the width dimension of the connection between the gold finger and the high-speed signal line is smaller than the width dimension of the connection between the gold finger and the external. Specifically, the gold finger includes a first connection part, a second connection part and a third connection part, the first connection part faces the high-speed signal line and is connected to the high-speed signal line; one end of the second connection part is connected to the first connection part, and the other end is connected to the third connection part, and the second connection part is connected to an external electrical connector; the width dimension of the first connection part is smaller than the width dimension of the second connection part, the width dimension of the third connection part can be the same as the width dimension of the second connection part, and the width dimension of the third connection part can also be smaller than the width dimension of the second connection part. On the basis of ensuring the requirements of the gold finger protocol, the present application partially narrows the width of the gold finger, so that the width of the connection between the gold finger and the high-speed signal line becomes narrower, reducing the difference between the gold finger line width and the high-speed signal line width, thereby reducing the characteristic impedance of the connection between the gold finger and the high-speed signal line, optimizing the impedance discontinuity point at the connection between the gold finger and the high-speed signal line, making the signal integrity at the gold finger better, and improving the high-frequency performance of the circuit board.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical module, characterized in that: include: Lower housing; An upper shell, covering the lower shell, and forming a containing cavity with the lower shell; The light emission submodule is disposed in the accommodating cavity and includes a laser chip for generating a light beam to realize light emission; A circuit board, on which a gold finger and a laser driver chip are arranged, the laser driver chip is connected to the gold finger through a high-speed signal line, and the gold finger is used to be electrically connected to an external electrical connector; the laser driver chip is signal-connected to the laser chip; the gold finger includes a first connection part, a second connection part, and a third connection part, the first connection part is connected to the high-speed signal line, the second connection part is connected to the electrical connector, and the width dimension of the first connection part is smaller than the width dimension of the second connection part; The width of the first connection portion connected to the high-speed signal line gradually increases to the width of the first connection portion connected to the second connection portion; The third connection portion faces away from the first connection portion and is connected to the second connection portion. The width of the third connection portion is smaller than the width of the second connection portion.

2. The optical module according to claim 1, characterized in that: The width of the first connecting portion is 4 mils less than the width of the second connecting portion.

3. The optical module according to claim 1, characterized in that: The two opposite sides of the second connection portion are both protruding from the two opposite sides of the first connection portion.

4. The optical module according to claim 3, characterized in that: A chamfer is provided at a connection between a side edge of the second connection portion protruding from the first connection portion and a side edge of the first connection portion.

5. The optical module according to claim 4, characterized in that: A side edge of the second connection portion differs from a side edge of the first connection portion by 2 mils.

6. The optical module according to claim 1, characterized in that: The second connecting portion is located at the middle 1 / 3 of the gold finger.

7. The optical module according to claim 1, characterized in that: The electrical connector is a spring-chip array connector, and the spring chips of the electrical connector are electrically connected to the pins of the gold fingers.

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