An optical module

Abstract

The present application provides an optical module, which uses a substrate as an optical platform for carrying devices, and a gasket is arranged on its upper surface, wherein a routing is arranged on the gasket, and a laser chip is fixed on the gasket and electrically connected to the routing. In addition, the gasket is electrically connected to the circuit board, so that the electrical signal from the circuit board can be transmitted to the laser chip, and the optical signal emitted by the laser chip is coupled into the optical fiber adapter through the focusing lens, thereby realizing the light emission function of the optical module; at the same time, the light incident surface of the optical fiber adapter is set as an inclined surface, and the central axis of the optical fiber and the optical axis of the focusing lens have an angle, thereby making the optical axis of the light beam coupled to the optical fiber through the focusing lens parallel or nearly parallel to the axial direction of the optical fiber, so as to realize the high-efficiency coupling of the signal light output by the laser chip into the optical fiber.

Description

Technical Field

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

[0002] Optical communication technology is used in new services and application modes such as cloud computing, mobile Internet, and video. Optical modules realize the function of photoelectric conversion in the field of optical communication technology and are one of the key components in optical communication equipment. The intensity of the optical signal input by the optical module to the external optical fiber directly affects the quality of optical fiber communication.

[0003] In the process of transmitting optical signals, the electrical signal from the circuit board is usually transmitted to the laser chip, which converts the electrical signal into an optical signal. The optical signal enters the air, and a lens, an optical fiber adapter and other devices are set on the optical path. The light emitted by the laser chip is coupled to the optical fiber adapter through the lens, and the optical fiber adapter is connected to the optical fiber. The efficiency of coupling the light emitted by the laser chip into the optical fiber affects the optical power of the optical signal, and the transmission loss of the light in the optical fiber also affects the optical power of the optical signal. Summary of the invention

[0004] The embodiment of the present application provides an optical module, which reduces the loss of light in the optical module and improves the light output power of the optical module.

[0005] The optical module provided in the embodiment of the present application mainly includes:

[0006] Circuit boards;

[0007] A light emitting part, electrically connected to the circuit board, for emitting light;

[0008] The light emitting part comprises:

[0009] substrate;

[0010] A gasket, arranged on the substrate, with a wiring electrically connected to the circuit board provided on its upper surface;

[0011] a laser chip, disposed on the pad and electrically connected to the trace, for emitting light;

[0012] A focusing lens, arranged on a transmission optical path of the light beam emitted by the laser chip, and used for converging the light beam to the optical fiber adapter;

[0013] The optical fiber adapter is arranged on the substrate, and its light incident surface is an inclined surface; in a plane parallel or approximately parallel to the upper surface of the substrate, the optical fiber adapter is inclinedly arranged on the substrate so that the central axis of the optical fiber in the optical fiber adapter is not parallel to the optical axis of the focusing lens.

[0014] As can be seen from the above embodiments, in this embodiment, the substrate is used as an optical platform for carrying the device, and a gasket is arranged on its upper surface, wherein a wiring is arranged on the gasket, and the laser chip is fixed on the gasket and electrically connected to the wiring. In addition, the gasket is electrically connected to the circuit board, so that the electrical signal from the circuit board can be transmitted to the laser chip, and the light emitted by the laser chip is coupled into the optical fiber adapter through the focusing lens, thereby realizing the light emission function of the optical module. In this embodiment, the substrate is used to replace the existing shell, which has a simple structure and effectively reduces the material cost of the light emission sub-mode. In addition, the substrate is an open structure, which can solve the packaging difficulties caused by the small space. At the same time, the light incident surface of the optical fiber adapter is set as an inclined surface, and the central axis of the optical fiber and the optical axis of the focusing lens have an angle, so that the optical axis of the light beam coupled to the optical fiber through the focusing lens is parallel or nearly parallel to the axial direction of the optical fiber, so that the signal light output by the laser chip is efficiently coupled into the optical fiber; and in this embodiment, the optical fiber adapter is arranged to be tilted in a two-dimensional plane on the substrate, without the need for additional components, which is more convenient for module packaging and saves materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 It is a schematic diagram of the connection relationship of optical communication terminals;

[0017] Figure 2 is a schematic diagram of the structure of an optical network unit;

[0018] Figure 3 A schematic diagram of the structure of an optical module provided in an embodiment of the present application;

[0019] Figure 4 A schematic diagram of the exploded structure of an optical module provided in an embodiment of the present application;

[0020] Figure 5 A schematic diagram of the structure of the light emitting part and the circuit board provided in the embodiment of the present application;

[0021] Figure 6 A schematic diagram of the exploded structure of the light emitting part and the circuit board provided in an embodiment of the present application;

[0022] Figure 7 A schematic diagram of the exploded structure of the light emitting part provided in the embodiment of the present application;

[0023] Figure 8 A schematic diagram of the assembly structure of the light emitting part provided in the embodiment of the present application;

[0024] Fig. 9 for Figure 8 A partial enlarged schematic diagram of the middle A area;

[0025] Fig.10 A schematic diagram of the exploded structure of the wire protection component and the circuit board provided in the embodiment of the present application;

[0026] Fig.11 A schematic diagram of the structure of a wire protection component provided in an embodiment of the present application;

[0027] Fig.12 A top view of a circuit board and a light emitting part provided in an embodiment of the present application;

[0028] Fig.13 A side view of a circuit board and a light emitting part provided in an embodiment of the present application;

[0029] Fig.14 for Fig.13 A magnified view of part B;

[0030] Fig.15 A schematic diagram of the structure of a substrate provided in an embodiment of the present application;

[0031] Fig.16 A top view of the light emitting portion provided for this embodiment;

[0032] Fig.17 A schematic diagram of a first split structure of an isolator, an anti-reflection film, and a fiber optic adapter provided in an embodiment of the present application;

[0033] Fig.18 A schematic diagram of a second split structure of the isolator, anti-reflection film and optical fiber adapter provided in an embodiment of the present application;

[0034] Fig.19 A first structural schematic diagram of a focusing lens and a fiber optic adapter provided in an embodiment of the present application;

[0035] Fig. 20 A second structural schematic diagram of a focusing lens and a fiber optic adapter provided in an embodiment of the present application;

[0036] Fig.21A A schematic diagram of the optical path structure of a light emitting part provided by the prior art;

[0037] Fig.21B for Fig.21A Simulation diagram of coupling efficiency of the optical path structure;

[0038] Fig.22A A schematic diagram of the optical path structure of the light emitting part provided by the prior art;

[0039] Fig. 22B for Fig.22A Simulation diagram of coupling efficiency of the optical path structure;

[0040] Fig.23 It is a simulation diagram of the coupling efficiency when the optical axis passes through the center of the second lens and enters the tilted optical fiber ferrule;

[0041] Fig.24A A schematic diagram of the optical path structure of the light emitting part provided in an embodiment of the present application;

[0042] Fig. 24B for Fig.24A Simulation diagram of coupling efficiency of the mid-light path structure. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in this embodiment to clearly and completely describe the technical solution in this embodiment. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0044] One of the core links of fiber-optic communication is the conversion of photoelectric signals. Fiber-optic communication uses optical signals carrying information to transmit in optical fibers / waveguides. The passive transmission characteristics of light in optical fibers can achieve low-cost and low-loss information transmission. Computers and other information processing devices use electrical signals, which requires the mutual conversion of electrical signals and optical signals during signal transmission.

[0045] Optical modules realize the above-mentioned photoelectric conversion function in the field of optical fiber communication technology. The mutual conversion between optical signals and electrical signals is the core function of optical modules. Optical modules realize electrical connection with external host computers through gold fingers on the circuit board. The main electrical connections include power supply, I2C signal, transmission data signal and grounding. The electrical connection method realized by gold fingers has become the standard method in the optical module industry. Based on this, circuit boards are an essential technical feature in most optical modules.

[0046] 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 an optical network unit 100, an optical module 200, an optical fiber 101 and a network cable 103;

[0047] One end of the optical fiber is connected to the remote server, and one end of the network cable 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 and the network cable; and the connection between the optical fiber and the network cable is completed by an optical network unit with an optical module.

[0048] The optical port of the optical module 200 is connected to the optical fiber 101, and a bidirectional optical signal connection is established with the optical fiber; the electrical port of the optical module 200 is connected to the optical network unit 100, and a bidirectional electrical signal connection is established with the optical network unit; the optical module realizes the mutual conversion between optical signals and electrical signals, thereby realizing the establishment of a connection between the optical fiber and the optical network unit; 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 unit 100, and the electrical signal from the optical network unit 100 is converted into an optical signal by the optical module and input into the optical fiber. The optical module 200 is a tool for realizing the mutual conversion of optical and electrical signals, and does not have the function of processing data. In the above-mentioned optical-electrical conversion process, the information does not change.

[0049] The optical network unit has an optical module interface 102, which is used to access the optical module and establish a bidirectional electrical signal connection with the optical module; the optical network unit has a network cable interface 104, which is used to access the network cable and establish a bidirectional electrical signal connection with the network cable; a connection is established between the optical module and the network cable through the optical network unit. Specifically, the optical network unit 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 unit acts as a host computer of the optical module to monitor the operation of the optical module.

[0050] At this point, the remote server establishes a two-way signal transmission channel with the local information processing device through optical fibers, optical modules, optical network units and network cables.

[0051] Common information processing equipment includes routers, switches, and electronic computers. The optical network unit 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.

[0052] Figure 2 Figure 1 is a schematic diagram of the structure of an optical network unit. Figure 2 As shown, a circuit board 105 is provided in the optical network unit 100, and a cage 106 is arranged on the surface of the circuit board 105; an electrical connector is arranged in the cage 106 for accessing 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 a protruding structure such as fins for increasing the heat dissipation area.

[0053] The optical module 200 is inserted into the optical network unit. Specifically, the electrical port of the optical module is inserted into the electrical connector in the cage 106 , and the optical port of the optical module is connected to the optical fiber 101 .

[0054] The cage 106 is located on the circuit board, and wraps the electrical connector on the circuit board in the cage; the optical module is inserted into the cage, and the cage fixes the optical module. The heat generated by the optical module is conducted to the cage through the optical module housing, and finally diffused through the heat sink 107 on the cage.

[0055] Figure 3A schematic diagram of the structure of an optical module 200 provided in an embodiment of the present application is shown in FIG. Figure 4 The present embodiment provides a schematic diagram of the exploded structure of the optical module 200. Figure 3 and 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 handle 203 , a circuit board 30 , a light emitting part 40 and a light receiving part 50 .

[0056] 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 tube 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 cover plate, and the cover plate is covered on the two side panels of the upper shell to form a wrapping cavity; the upper shell can also include two side walls located on both sides of the cover plate and perpendicular to the cover plate, and the two side walls are combined with the two side panels to achieve the upper shell covering the lower tube shell.

[0057] 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 unit; the other opening is an optical port 205, which is used for external optical fiber access to connect the optical emitting part 40 and the optical receiving part 50 inside the optical module; optoelectronic devices such as the circuit board 30, the optical emitting part 40 and the optical receiving part 50 are located in the encapsulating cavity.

[0058] The upper shell and the lower tube shell are combined to facilitate installation of components such as the circuit board 30, the light emitting part 40 and the light receiving part 50 into the shell. The upper shell and the lower tube shell form the outermost packaging protection shell of the optical module. The upper shell and the lower tube 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 structure. In this way, when assembling components such as circuit boards, positioning components, heat dissipation and electromagnetic shielding structures cannot be installed, which is not conducive to production automation.

[0059] The unlocking handle 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.

[0060] The unlocking handle 203 has a snap-fit ​​structure that matches the cage of the host computer; pulling the end of the unlocking handle can make the unlocking handle move relative to the surface of the outer wall; the optical module is inserted into the cage of the host computer, and the snap-fit ​​structure of the unlocking handle fixes the optical module in the cage of the host computer; by pulling the unlocking handle, the snap-fit ​​structure of the unlocking handle moves accordingly, thereby changing the connection relationship between the snap-fit ​​structure and the host computer, so as to release the snap-fit ​​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.

[0061] The circuit board 30 is provided with circuit traces, electronic components (such as capacitors, resistors, transistors, MOS tubes) and chips (such as microprocessor MCU2045, laser driver chip, limiting amplifier, clock data recovery CDR, power management chip, data processing chip DSP) and the like.

[0062] The circuit board 30 connects the electrical components in the optical module together according to the circuit design through circuit routing to achieve electrical functions such as power supply, electrical signal transmission and grounding.

[0063] The circuit board 30 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also realize the load-bearing function, such as the rigid circuit board can stably carry the chip; the rigid circuit board can also be inserted into the electrical connector in the upper computer cage. Specifically, a metal pin / gold finger is formed on the end surface of one side of the rigid circuit board for connecting with the electrical connector; these are not easy to achieve with flexible circuit boards.

[0064] 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.

[0065] The optical module also includes a light emitting part and a light receiving submodule, which can be collectively referred to as an optical submodule. Figure 4 As shown, the optical module provided in the embodiment of the present invention includes a light emitting part 40 and a light receiving part 50. The light emitting part 40 is used to convert an electrical signal into an optical signal, and the generated optical signal is transmitted to the outside of the optical module through the optical fiber socket 60; the light receiving part 50 is used to convert the optical signal received by the optical fiber socket 60 into an electrical signal. In this embodiment, the light receiving part 50 is arranged on the surface of the circuit board 30. In another common packaging method, the light receiving submodule is physically separated from the circuit board, and the electrical connection is realized through the flexible board.

[0066] For some optical modules, the use environment is relatively good. For example, there are air conditioners inside the data center to control the temperature and humidity, so the sealing requirements for the device are not high, but the cost of the finished product is higher. In addition, for the light emitting part, the tube shell is encapsulated. The tube shell is usually machined or molded, so the tube shell design is relatively complex and the production cost is high. In addition, when encapsulating the module, the semiconductor cooler, light emitting chip, lens and other components need to be fixed in the tube shell. The space inside the cavity of the light emitting part is very small, which is not convenient for production operations. Figure 5 A schematic diagram of the structure of the light emitting part and the circuit board provided in the embodiment of the present application, Figure 6 This is a schematic diagram of the exploded structure of the light emitting part and the circuit board provided in the embodiment of the present application. Figure 5 and 6 As shown, the light emitting part 40 in this embodiment is packaged in a non-airtight manner, is physically separated from the circuit board 30, and is electrically connected by metal wire bonding, such as gold wire. For the light emitting part 40, this embodiment adopts a packaging method in which the substrate is used as an optical platform, and the laser chip, semiconductor refrigerator and other devices are placed on the substrate.

[0067] It should be noted that the optical transmission part 40 in this embodiment includes four optical paths of the same wavelength, and the data transmission rate is improved by increasing the number of optical paths. In other embodiments, other numbers can also be set. In addition, the following embodiment uses one optical path as an example to illustrate the scheme of this implementation.

[0068] Figure 7 A schematic diagram of the exploded structure of the light emitting part provided in the embodiment of the present application, Figure 8 This is a schematic diagram of the assembly structure of the light emitting part provided in the embodiment of the present application. Figure 7 and 8 As shown, in order to reduce production costs and provide a flat carrying surface for devices such as laser chips and semiconductor refrigerators, the light emitting part 40 in this embodiment includes a substrate 41 as an optical platform, and devices such as TEC (Thermoelectric cooler, semiconductor refrigerator) 42, a gasket 43, a laser chip 44, a collimating lens 45, an isolator 46, an anti-reflection film (AR film) 47, and an optical fiber adapter 48 are arranged on the upper surface of the substrate 41.

[0069] In order to facilitate the heat dissipation of the components arranged on the upper surface of the substrate 41, the lower surface of the substrate 41 can be fixed to the housing of the optical module, such as the lower housing 201, by means of a heat-conducting adhesive. In this way, the heat generated by the components in the light emitting part 40 can be conducted to the housing of the optical module through the substrate 41, and then conducted to the outside of the optical module through the housing of the optical module. Further, considering factors such as heat dissipation effect, processing accuracy, and thermal expansion, the substrate 41 in this embodiment is made of tungsten copper, that is, an alloy composed of tungsten and copper. Of course, in other embodiments, it can also be made of other materials, such as ceramics.

[0070] TEC42 is used to export the heat generated by the laser chip 44 from the substrate 41. Specifically, TEC42 includes an upper heat exchange surface and a lower heat exchange surface. A gasket 43 is provided on the top of the upper heat exchange surface, and the upper heat exchange surface is used to absorb the heat generated by the laser chip 44 transferred from the gasket 43. The bottom of the upper heat exchange surface is connected to the lower heat exchange surface, and the lower heat exchange surface is fixed to the upper surface of the substrate 41. Therefore, the substrate 41 can be used to export the heat of the lower heat exchange surface of the TEC42 to the outside of the optical module.

[0071] Fig. 9 for Figure 8 A partial enlarged schematic diagram of area A in the middle. Fig. 9 As shown, the gasket 43 in this embodiment includes an insulating heat-conducting layer 431 and a metallized circuit pattern (also called routing). The insulating heat-conducting layer 431 can be made of a ceramic material with good thermal conductivity, good insulation and high processing accuracy, and is certainly not limited to ceramic. Among them, in order to facilitate the installation of various electrical components on the gasket 43, in this embodiment, the metallized circuit pattern arranged on the upper surface of the insulating heat-conducting layer 431 includes a high-speed signal line 432 and a ground line 433, and the lower surface of the insulating heat-conducting layer 431 is in contact with the upper surface of the TEC42. The cathode of the laser chip 44 can be fixed on the ground line 433 of the gasket 43 by welding or conductive glue, and the anode of the laser chip 44 can be connected to the high-speed signal line 432 by wire bonding.

[0072] It should be noted that the design shape and layout of the high-speed signal line 432 and the ground line 433 are not limited to the method provided in this embodiment. In other embodiments, they can be designed according to the requirements of signal transmission rate, layout components, etc.

[0073] During the operation of the optical module, the high-frequency data electrical signal from the host computer is transmitted to the clock data recovery chip, laser driver chip and other chips arranged on the circuit board through the gold finger on the circuit board 30, and the high-frequency data electrical signal received by the optical module is processed by the above-mentioned clock data recovery chip, laser driver chip and other chips, so as to transmit the shaped high-frequency data electrical signal to the laser chip 44 arranged on the gasket 43, so that the laser chip emits an optical signal, and, in this embodiment, a ground wire and a high-frequency signal line (not shown in the figure) are also arranged on the circuit board 30. At the same time, the high-frequency signal line on the circuit board 30 is connected to the high-speed signal line 432 on the gasket 43 through the wire bonding, and the ground wire on the circuit board 30 is connected through the ground wire 433 on the wire bonding gasket 43, so that the electrical signal from the circuit board 30 can be transmitted to the laser chip 44. It should be noted that backlight detectors, resistors, capacitors and other components can also be arranged on the gasket 43, and each component can be electrically connected to the circuit board 30 through the corresponding routing arranged on the gasket 45, so as to achieve stable light emission of the laser chip 44.

[0074] Fig.10 This is a schematic diagram of the exploded structure of the wire protection component and the circuit board provided in the embodiment of the present application. Fig.10 As shown, in this embodiment, since the diameter of the bonding wire between the circuit board 30 and the gasket 43 is usually relatively thin, in order to prevent the circuit board 30 and the gasket 43 from moving relative to each other and causing the bonding wire to be disconnected, and considering the impedance matching and other issues, there are also requirements for the length of the bonding wire connecting the circuit board 30 and the high-frequency signal line on the gasket 43. Therefore, in order to ensure the stability of the relative position of the circuit board 30 and the gasket 43, in this embodiment, the lower surface of the end of the circuit board 30 close to the substrate 41 is fixed to the upper surface of the substrate 41.

[0075] Fig.11 This is a schematic diagram of the structure of the wire protection component provided in the embodiment of the present application. Fig.10 and 11 As shown, in order to prevent the bonding wires connecting the circuit board 30 and the gasket 43 from being touched, a bonding wire protection component 70 is provided on the circuit board 30 in this embodiment. To prevent the bonding wire protection component 70 from being conductive, it can be made of non-metallic material, such as plastic material, and fixed to the circuit board 30 with non-conductive glue. The bonding wire cover for connecting the gasket 43 and the circuit board 30 is provided under the bonding wire protection component 70, thereby preventing the bonding wires from being crushed, damaged, etc. due to being touched.

[0076] Furthermore, in order to facilitate the heat dissipation of the components located below the wire bonding protection component 70 and reduce the footprint of the wire bonding protection component 70 on the circuit board, as shown in FIG. Fig.11As shown, in this embodiment, the wire bonding protection component 70 is configured to be composed of a protection plate 71 and two or more support members 72, wherein the protection plate 71 is a flat plate structure, and its specific shape can be set according to the layout requirements of the circuit board 30. For example, in this embodiment, it is designed as an L-shaped structure. One end of the support member 72 is fixedly connected to the lower surface of the protection plate 71, and the other end is fixed to the upper surface of the circuit board 30 by glue or the like.

[0077] Fig.12 This is a top view of the circuit board and the light emitting part provided in the embodiment of the present application. Fig.12 As shown, since the laser chip 44 and the gasket 43 are also connected by wire bonding, in addition to setting the wire bonding connection between the circuit board 30 and the gasket 43 below the protection plate 71 in the wire bonding protection component 70, the gasket 43 is also set below the protection plate 71 in the wire bonding protection component 70. In addition, the high-frequency data signal, bias signal and other signals received by the laser chip 44 need to be processed accordingly by the laser driver chip (not shown in the figure) set on the circuit board 30 before being sent to the laser chip 44, and the laser driver chip is usually also electrically connected to the circuit board 30 through wire bonding. Therefore, in this embodiment, the device driver chip is also set close to the gasket 43 and is set below the wire bonding protection component 70.

[0078] Therefore, the present embodiment uses the substrate 41 to replace the existing housing of the light emitting part, which has a simple structure and effectively reduces the material cost of the light emitting sub-light module. Moreover, the upper part of the substrate 41 is an open structure, which can solve the packaging difficulty problem caused by the small space in the housing. In addition, by setting the assembly method between the substrate 41 and the circuit board 30 and setting the wire protection component 70, the performance of the module can be effectively guaranteed.

[0079] Fig.13 A side view of a circuit board and a light emitting part provided in an embodiment of the present application, Fig.14 for Fig.13 This is an enlarged view of part B. Fig.13 and 14 As shown, since the light emitted by the laser chip 44 is divergent light, and the light entry aperture of the optical fiber is generally small, in order to improve the light coupling efficiency, the present embodiment sets the light entry surface of the focusing lens 45 toward the light exit surface of the laser chip 44, and the light exit surface of the focusing lens 45 toward the light entry surface of the optical fiber adapter 48. The light emitted by the laser chip 44 is optically coupled as divergent light into the optical fiber in the optical fiber adapter 48 by the focusing lens 45. Since the light entry aperture of the optical fiber is generally small, in order to ensure the light coupling efficiency, the present embodiment adjusts the position of the focusing lens 45 so that the focus of the focusing lens 45 is located near the end face of the optical fiber.

[0080] In addition, in order to make the light converge after passing through the focusing lens 45, the direction of the optical axis does not change before and after the convergence, that is, the light is injected along the center of the focusing lens. This injection direction can ensure that the light after the convergence retains the pattern spot distribution before the convergence to the greatest extent, presenting a regular circular light spot, which is conducive to improving the efficiency of the subsequent coupling process. Therefore, in this embodiment, the light emitted by the laser chip 44 can be set to be injected along the center of the focusing lens 45, specifically, the light converges through the center of the focusing lens. In an ideal state, the center of the light beam emitted by the laser chip 44 passes through the optical axis of the focusing lens 45. Therefore, in order to achieve the alignment of the laser chip 44 and the focusing lens 45, and in combination with the existing lens and laser chip size characteristics, this embodiment sets the focusing lens 45 on the upper surface of the TEC42, that is, the gasket 43 is used to make up for the height difference between the laser chip 44 and the focusing lens 45.

[0081] Since the optical fiber's light entry aperture is generally small, the stability of the relative position between the focusing lens 45 and the optical fiber adapter 48 is also very important. Based on the above reasons, the optical fiber adapter 48 is also fixed to the upper surface of the substrate 41 in this embodiment. In order to allow more light emitted by the focusing lens 45 to enter the optical fiber of the optical fiber controller 48, in an ideal state, the optical axes of the focusing lens 45 and the optical fiber controller 48 should be in the same horizontal plane or approximately in the same horizontal plane.

[0082] Fig.15 This is a schematic diagram of the structure of the substrate provided in the embodiment of the present application. Fig.15 As shown, in order to achieve alignment between the focusing lens 45 and the optical fiber manipulator 48, the present embodiment further designs the substrate 41, wherein a recessed portion 412 is provided in the middle region of the substrate 41, so that the upper surface of the substrate 41 is divided into a first upper surface 411 and a second upper surface 413 by the recessed portion 412, and the first upper surface 411 and the second upper surface 413 are respectively located on both sides of the recessed portion 412.

[0083] The first upper surface 411 is used to be fixedly connected with the lower surface of the end of the circuit board 30; the second upper surface 413 is used to set the optical fiber adapter 48; the recessed portion 412 is used to set the semiconductor refrigerator 42, wherein the lower surface of the semiconductor refrigerator 42 contacts the bottom of the recessed portion, the upper surface is provided with a gasket 43 and a focusing lens 45, and the upper surface of the gasket 43 is provided with a laser chip 44, so that the upper surface of the gasket 43 and the upper surface of the circuit board 30 are in the same horizontal plane or approximately in the same horizontal plane, so as to facilitate wiring. In addition, the optical axis of the optical fiber adapter 48 and the optical axis of the focusing lens 45 can also be in the same horizontal plane or approximately in the same horizontal plane, so as to improve the optical coupling efficiency. In this embodiment, by setting the substrate 41 as a structure with a recessed portion, not only its bearing function is realized, but also the alignment function between the components is effectively realized. Compared with the flat substrate 41, it is more convenient to package and can also effectively save the raw materials used to adjust the height of the component.

[0084] like Fig.14 As shown, in order to isolate the reflected light in the optical path, an isolator 46 is usually provided on the light-emitting side of the embodiment. Based on the characteristic that the light emitted by the laser chip 44 is divergent light, the isolator 46 is provided on the light-emitting side of the focusing lens 45 in the embodiment. In addition, based on the small available space on the TEC 42 and other reasons, the isolator 46 is provided on the second upper surface 413 of the substrate 41 in the embodiment.

[0085] The isolator 46 in this embodiment is based on the principle of passing light polarization and only allows light to pass in one direction. Based on the working principle of the isolator 46, by adjusting the angle between the polarization direction of the laser emitted by the laser chip and the polarization direction of the isolator 46, the coupling power between the laser chip 44 and the isolator 46 is adjusted, and then the output optical power of the optical module can be controlled.

[0086] In addition, for high-speed optical modules, such as 400G products, higher requirements are placed on the optical power coupling efficiency. When light enters the optical fiber from the air, about 4% of the light is emitted, which causes a loss in coupling efficiency. Therefore, this embodiment also provides an anti-reflection film 47 between the isolator 46 and the optical fiber adapter 48, which can effectively reduce the end face emission at the optical fiber adapter 48.

[0087] Fig.16 A top view of the light emitting portion provided in this embodiment. Fig.16As shown, in order to reduce the light reflected by the isolator 46 and return to the laser chip 44 and reduce the return loss, the present embodiment sets the normal line of the light incident surface of the isolator 46 (or the normal line of the light incident surface) and the optical axis of the focusing lens 45 to have an angle θ, and the angle value can be set as needed, for example, set to 5°, 10°, etc. It should be noted that the present embodiment takes the optical axis of the light beam emitted by the laser chip 44 (or the light emitting direction of the laser chip 44) and the optical axis of the focusing lens 45 as an example of coincidence or approximate coincidence. In other embodiments, the two may not coincide, and then the normal line of the light incident surface of the isolator 46 and the optical axis of the focusing lens 45 have an angle θ, then the normal line of the light incident surface of the isolator 46 and the optical axis of the light beam emitted by the laser chip 44 have an angle θ.

[0088] In this way, the light emitted by the laser chip 44 is sequentially focused by the lens 45, the isolator 46 and the anti-reflection film 47, and then emitted into the optical fiber in the optical fiber adapter 48 through the air. If the optical fiber is vertically injected into the end face of the optical fiber, it is easy to control the angle relationship between the light emission direction of the laser chip and the optical fiber ferrule by this method, but vertical injection will cause the reflected light to return along the original optical path, and the returned light will return to the laser chip 44, which will further affect the light emission of the laser chip 44.

[0089] Therefore, in order to prevent the reflected light from returning along the original optical path, the optical path is designed so that the light is not incident perpendicularly to the optical fiber end face. In order to achieve the non-perpendicular incidence of the light on the optical fiber end face, the light incident surface of the optical fiber adapter 48 is set to be an inclined surface in this embodiment.

[0090] Fig.17 This is a schematic diagram of a first split structure of an isolator, an anti-reflection film, and a fiber optic adapter provided in an embodiment of the present application. Fig.18 This is a schematic diagram of the second split structure of the isolator, anti-reflection film and optical fiber adapter provided in the embodiment of the present application. Fig.17 As shown in FIG. 1 and FIG. 18 , based on the design that the normal line of the light incident surface of the isolator 46 has an angle with the optical axis of the focusing lens 45, the light incident surface of the optical fiber adapter 48 also has a certain inclination, and in order to facilitate fixing the isolator 46, the anti-reflection film 47 and the optical fiber adapter 48 on the substrate 41, this embodiment uses glue, silver glue, etc. to fix the three together, wherein the anti-reflection film 47 can be fixed on the light incident end face of the optical fiber adapter 48, and then the isolator 46 is fixed on the anti-reflection film 47. When the module is packaged, the gasket 43, the laser chip 44 and the focusing lens 45 can be mounted in a passive manner, and then the optical assembly composed of the isolator 46, the anti-reflection film 47 and the optical fiber adapter 48 is actively coupled.

[0091] like Fig.18As shown, by setting the end face of the optical fiber adapter 48 to have a first inclination angle θ1, wherein the inclination angle is equal to the angle between the normal line of the end face of the optical fiber adapter 48 and the optical axis of the focusing lens 45, after the isolator 46 and the optical fiber adapter 48 are mounted together, the normal line of the light incident surface of the isolator 46 and the optical axis of the focusing lens 45 also have the first inclination angle θ1. In addition, as Fig.18 As shown, in this embodiment, the port 482 in the optical fiber adapter 48 for inserting the optical fiber is set to a conical structure. When packaging, it is inserted into the optical fiber adapter 48 through the port 482, and then glue is poured into the conical port 482, which facilitates the fixation of the optical fiber.

[0092] In this embodiment, a fiber optic ferrule can be provided in the fiber optic adapter 48. The fiber optic ferrule is formed by a ceramic cylinder wrapping an optical fiber. The central axis of the fiber optic ferrule is the same as the central axis of the optical fiber. The light entrance surface of the fiber optic ferrule is ground into an inclined surface, that is, the light entrance surface of the optical fiber is ground into the same inclined surface, so that the light entrance surface of the fiber optic adapter 48 can have a certain inclination angle, or the fiber optic adapter 48 is also set to the same inclined surface as the light entrance surface of the optical fiber. Further, the optical fiber is composed of a core layer and a cladding layer with different refractive indices, and the light is totally reflected at the interface between the core layer and the cladding layer, thereby constraining the transmission in the core layer.

[0093] The premise for total reflection to occur is to have a sufficiently large incident angle. Therefore, for light to be totally reflected in an optical fiber, it is required that the refraction angle is small enough after the light is refracted at the optical fiber light entrance surface, so that the light has a sufficiently large incident angle when it is reflected again in the optical fiber. And in order to form a sufficiently small refraction angle after refraction, it is necessary to have a sufficiently small incident angle during refraction; in order to achieve better coupling efficiency, it is required that the optical axis after entering the optical fiber is parallel to the central axis of the optical fiber, and the light beam entering the optical fiber is symmetrical about the central axis. Therefore, the light entering the optical fiber light entrance surface has a specific range of incident angles.

[0094] After the light incident surface of the optical fiber adapter 48 is set to have a certain inclination angle, the light beam converged by the focusing lens 45, especially the light beam near the optical axis, will be incident on the light incident surface of the optical fiber in a non-vertical direction, the incident angle increases, and the refraction angle also increases, which is not conducive to the total reflection of the light entering the optical fiber at the interface between the optical fiber core layer and the cladding, thereby reducing the coupling efficiency. In view of the above problems, the present embodiment optimizes the placement position of the optical fiber adapter 48 on the substrate 41, so that it is in a plane parallel or approximately parallel to the upper surface of the substrate 41, and the optical fiber adapter 48 is tilted on the substrate 41, so that the central axis of the optical fiber in the optical fiber adapter 48 is not parallel to the optical axis of the focusing lens 45.

[0095] Fig.19 This is a first structural diagram of a focusing lens and a fiber optic adapter provided in an embodiment of the present application. Fig.19As shown, in this embodiment, the end face of the optical fiber adapter 48 is set to have a first inclination angle θ1, for example, it is set to 7°, 8°, etc. but not limited to this value. At the same time, the light incident surface of the internal optical fiber (not shown in the figure) is also adapted to have the first inclination angle θ1. Then, along the inclination direction of the end face of the optical fiber adapter 48, the central axis of the optical fiber adapter 48 is set to have a second inclination angle θ2 relative to the optical axis of the focusing lens 45, for example, it is set to 3°, 2°, etc. but not limited to this value.

[0096] In addition, since the isolator 46 and the anti-reflection film 47 are fixed on the end face of the optical fiber adapter 48 in this embodiment, the light incident surface of the isolator 46 can have an inclination angle θ relative to the focusing lens 45, that is, the normal line of the light incident surface of the isolator 46 and the optical axis of the focusing lens 45 have an angle θ.

[0097] Fig. 20 This is a second structural diagram of the focusing lens and the optical fiber adapter provided in the embodiment of the present application. Fig. 20 As shown, through the above arrangement, the optical axis direction of the light beam refracted into the optical fiber can be made parallel or nearly parallel to the central axis of the optical fiber, thereby effectively improving the optical coupling efficiency.

[0098] The solution provided in this embodiment is compared with the existing solution. The light emitted by the laser chip 44 is symmetrical about the optical axis, and the light entering the optical fiber is also symmetrical about the optical axis. Three typical light rays are used as an example for illustration, and the light at the optical axis is used for schematic description.

[0099] Fig.21A A schematic diagram of the optical path structure of a light emitting part provided by the prior art, Fig.21B for Fig.21A Simulation diagram of coupling efficiency of the optical path structure. Fig.21A As shown, the focusing lens in this embodiment is composed of a first lens 45a and a second lens 45b. The central axis of the fiber optic adapter (not shown in the figure) is parallel to the optical axis direction of the output light beam of the laser chip 44. The central axis of the fiber optic adapter is set to be parallel to the central axis of the fiber optic ferrule (not shown in the figure), and the central axis of the fiber optic ferrule is parallel to the central axis of the optical fiber 481 in the fiber optic ferrule (ideally, they coincide). The divergent light emitted by the laser chip 44 is converged into parallel light by the first lens 45a, and the parallel light is converged by the second lens 45b and then incident on the light incident surface of the optical fiber 481. After two convergences, the light maintains the original optical axis direction, and the spot shape does not change. Ideally, it is a circular spot. The converged light meets the angle requirement for total reflection of the optical fiber, and the optical axis of the converged light is perpendicular to the light incident surface of the optical fiber. As shown Fig.21B As shown, the light is converged through the center of the focusing lens, and the converged light is coupled to the optical fiber 481. Most of the light is transmitted through the optical fiber, and less light is distributed around the optical fiber. Fig.21AThe optical path structure achieves higher coupling efficiency.

[0100] The optical axis is perpendicular to the light incident surface, and the refraction that occurs at this time has the smallest incident angle (0°) and the smallest refraction angle. Fig.21A The adopted optical path design can meet the angle requirement of total reflection of optical fiber, and the light spot shape is also conducive to optical coupling. However, the reflected light generated at the optical fiber incident surface will return along the original optical path, thereby affecting the light output of the laser chip 44.

[0101] therefore, Fig.21A and Fig.21B The advantage of this optical path design is that the center of the focusing lens is used to converge the optical path, which can maintain a better light spot shape. The disadvantage is that the reflected light generated by the optical fiber incident surface will return to the laser chip along the original optical path.

[0102] Fig.22A The schematic diagram of the optical path structure of the light emitting part provided by the prior art is as follows: Fig. 22B for Fig.22A Simulation diagram of coupling efficiency of optical path structure. It should be noted that in the plan view, the different inclination directions of the optical fiber bevel are only different from the viewing angle. The optical fiber is a cylinder, and the inclination direction of the bevel is different when the viewing angle is rotated. Fig.22A As shown, the central axis of the optical fiber 481 is parallel to the light-emitting optical axis direction of the laser chip 44. The divergent light emitted by the laser chip 44 is converged into parallel light by the first lens 45a. The parallel light is converged by the second lens 45b and then incident on the light-entering surface of the optical fiber 481. In order to prevent the reflected light from being reversibly reflected back to the laser chip, the light-entering surface of the optical fiber 481 is an inclined surface. In order to utilize the principle of refraction to make the light entering the optical fiber meet the condition of total reflection, the light is incident on the non-central position of the second lens 45b, and the light is converged by the non-center of the second lens 45b. After the second lens 45b changes the direction of the optical axis of the light, it is incident on the light-entering inclined surface of the optical fiber 481; the light is refracted on the light-entering inclined surface and then incident on the optical fiber 481.

[0103] like Fig.22A As shown, Fig.21A In contrast, the incident light surface of the optical fiber is an inclined surface, while the central axis of the optical fiber in the optical fiber ferrule remains unchanged. In order to make the refracted light meet the conditions of total reflection, the convergent light must not be maintained. Fig.21A Specifically, the optical axis maintains Fig.21A If the direction in the laser is parallel to the light-emitting axis of the laser chip, the light will enter the light-entering surface in a non-vertical direction, the incident angle will decrease, and the refraction angle will also decrease, which is not conducive to total reflection. In order to increase the incident angle, Fig.22A The plan has changed Fig.21A The optical axis direction in the image is not parallel to the light output axis direction of the laser chip after being converged by the second lens 45b, so as to increase the incident angle during refraction.

[0104] pass Fig. 22B As can be seen from the simulation diagram in FIG. 1 , the optical axis direction of the light after being converged by the second lens 45b changes so that the converged light is aligned with Fig.21B The propagation direction in the optical fiber 481 is different, and the light is converged at the non-central position of the second lens 45b. In order to achieve total reflection in the light, the light entering the light-entering surface of the optical fiber 481 has a specific incident angle range, and the angle range also limits the light converged by the second lens 45b, and cannot be converged through the center of the second lens 45b.

[0105] However, using Fig.22A In this optical path design, the optical axis does not pass through the center of the second lens 45b. After passing through the second lens 45b, the direction of the optical axis is changed, the light spot will undergo a significant deformation, the shape of the light spot is distorted, the mode field distribution of the light spot is irregular, and the efficiency of coupling into the optical fiber is significantly reduced.

[0106] Fig.22A and Fig. 22B The advantage of this optical path design is that it prevents the reflected light generated by the optical fiber incident surface from returning to the laser chip along the original optical path. The disadvantage is that the center of the second lens 45b is not used to converge the optical path, and the shape of the light spot after convergence is greatly deteriorated.

[0107] Fig.23 This is a simulation diagram of the coupling efficiency when the optical axis passes through the center of the second lens and enters the tilted optical fiber ferrule. Fig.23 As shown, the light incident surface of the optical fiber 481 is an inclined surface. The light emitted by the laser chip 44 is collimated by the first lens 45a, and then converged by the second lens 45b and emitted into the optical fiber 481 of the optical fiber adapter; the light is converged through the center of the second lens 45b, and the central axis of the optical fiber is parallel to the illumination of the second lens 45b. The light is refracted and coupled into the optical fiber 481. It can be seen that a large amount of light is emitted from the optical fiber 481 of the optical fiber adapter, and the coupling efficiency is low.

[0108] Fig.24A This is a schematic diagram of the optical path structure of the light emitting part provided in the embodiment of the present application. Fig. 24B for Fig.24A Simulation diagram of coupling efficiency of the optical path structure. Fig.24A As shown, in this embodiment, the central axis of the optical fiber 481 is set to be parallel to the central axis of the optical fiber adapter, and the central axis of the optical fiber adapter is set to be not in the same direction as the light-emitting axis of the laser chip, so that the light-emitting axis direction of the laser chip is not parallel to the central axis of the optical fiber; the divergent light emitted by the laser chip 44 is converged into parallel light by the first lens 45a, and the parallel light is converged by the second lens 45b and then emitted into the inclined surface of the optical fiber 481.

[0109] In order to prevent the reflected light from being reversibly reflected back to the laser chip, the light entrance surface of the optical fiber is an inclined surface; in order to use the refraction principle to inject light into the optical fiber, the light emitted by the laser chip is emitted through the center of the second lens 45b, and the original optical axis direction is not changed during the focusing process. When it is injected into the inclined light entrance surface of the optical fiber 481, the light is refracted through the light entrance surface of the optical fiber 481 and enters the optical fiber 481. The signal light enters the optical fiber 481 through the refracted inclined surface, and the inclination angle of the inclined surface and the inclination angle of the optical fiber adapter are coordinated and controlled so that the optical axis direction of the signal light refracted into the optical fiber 481 is parallel or nearly parallel to the central axis of the optical fiber 481.

[0110] Fig.24A The purpose of the provided optical path design is to maintain a good light spot shape after the light is converged, and to match the incident light slope of optical fiber 481, so that the optical axis direction of the signal light refracted into optical fiber 481 is parallel to the central axis of optical fiber 481, so as to achieve high-efficiency coupling of light into the optical fiber.

[0111] In order to keep a better spot shape after the light is converged, the light is converged through the center of the second lens 45b. The light is emitted through the center of the second lens 45b, and the direction of the optical axis after focusing does not change. The light after convergence maintains the spot shape before convergence. In an ideal state, a circular spot shape can be maintained, which is beneficial to improving the efficiency of optical coupling.

[0112] In order to prevent the reflected light generated by the optical fiber incident surface from returning to the laser chip along the original optical path, the optical fiber ferrule light incident surface / optical fiber light incident surface is designed to be an inclined surface. However, Fig.21A The optical path structure shown shows that when light is converged through the center of the second lens 45b, the subsequent optical fiber incident surface matched therewith cannot be an inclined surface, so that the light refracted at the incident surface can be transmitted by total reflection; Fig.22A The optical path structure shown indicates that when the light incident surface is an inclined surface, the light matching it in front cannot be converged through the center of the second lens 45b, so that the light refracted at the light incident surface can be transmitted by total reflection.

[0113] In order to make the light coupled into the optical fiber undergo total reflection, the embodiment of the present application provides a new structural design, by tilting the optical fiber adapter 48 on the substrate 41 so that the central axis of the optical fiber 481 is not parallel to the light emitting direction of the laser chip, thereby tilting the optical fiber at a certain angle relative to the light emitting direction of the laser chip.

[0114] After the light refracts into the optical fiber, it forms a specific angle with the central axis of the optical fiber. Fig.21A , Fig.22A and Fig.24A This is also an inevitable requirement for the full emission of light in the optical fiber.

[0115] like Fig. 24BAs shown, using Fig.24A In the optical path structure, the light is converged through the center of the second lens 45b, the light incident surface of the optical fiber is inclined, the light converged by the second lens 45b can be efficiently coupled into the optical fiber, and most of the light enters the optical fiber.

[0116] Fig.22A and Fig.24A In the example, the incident angle of the optical fiber is taken as a reference, and the angle after the light is refracted is the same. The difference is: Fig.22A The central axis of the optical fiber in the laser chip is parallel to the light emitting direction of the laser chip, and the optical axis passes through the non-central area of ​​the second lens 45b; Fig.24A The central axis of the optical fiber is not parallel to the light emitting direction of the laser chip, and the optical axis passes through the central area of ​​the second lens 45b. In addition, the optical path design provided in the embodiment of the present application realizes that the optical axis direction of the signal light refracted into the optical fiber 481 is parallel to the central axis of the optical fiber, and the light is efficiently coupled into the optical fiber.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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 invention.

Claims

1. An optical module, characterized in that: include: Circuit boards; A light emitting part, electrically connected to the circuit board, for emitting light; The light emitting part comprises: substrate; A gasket, arranged on the substrate, with a wiring electrically connected to the circuit board provided on its upper surface; a laser chip, disposed on the pad and electrically connected to the trace, for emitting light; A focusing lens is arranged on the transmission optical path of the light beam emitted by the laser chip, and is used to converge the light beam to the optical fiber adapter; wherein the light beam emitted by the laser chip is converged through the center of the focusing lens, and the direction of the optical axis remains unchanged after focusing; An isolator is arranged on the light exit side of the focusing lens, and a normal line of a light incident surface of the isolator has an inclination angle with the optical axis of the focusing lens; The optical fiber adapter is arranged on the substrate, and its light incident surface is an inclined surface; the isolator is located on the light incident path of the optical fiber adapter; an optical fiber is arranged inside the optical fiber adapter, and the optical fiber light incident end face is flush with the optical fiber adapter light incident end face, and the optical fiber light incident end face and the optical fiber adapter light incident end face present the same inclined surface; in a plane parallel or approximately parallel to the upper surface of the substrate, the optical fiber adapter is tilted on the substrate, and the central axis of the optical fiber in the optical fiber adapter is not parallel to the optical axis of the focusing lens.

2. The optical module according to claim 1, characterized in that: The light emitting part also includes: The isolator is arranged on the substrate and between the lens and the optical fiber adapter, and the normal line of the light incident surface of the isolator has a certain angle with the optical axis of the focusing lens.

3. The optical module according to claim 2, characterized in that: The end surface of the optical fiber adapter is an inclined surface, and the isolator is mounted on the end surface of the optical fiber adapter.

4. The optical module according to claim 3, characterized in that: The light emitting part also includes: An anti-reflection film is mounted on the end face of the optical fiber adapter, wherein the isolator is mounted on the anti-reflection film.

5. The optical module according to claim 1, characterized in that: The lower surface of the end portion of the circuit board is arranged on the upper surface of the end portion of the substrate, and the lower surface of the substrate is in contact with the housing of the optical module.

6. The optical module according to claim 2, characterized in that: The substrate is provided with a recessed portion, and the upper surface of the substrate includes a first upper surface and a second upper surface located on both sides of the recessed portion, wherein: The lower surface of the end of the circuit board is arranged on the first upper surface; A semiconductor refrigerator is arranged in the recessed portion, the lower surface of the semiconductor refrigerator is in contact with the bottom of the recessed portion, the upper surface of the semiconductor refrigerator is provided with the gasket and the focusing lens, and the upper surface of the gasket and the upper surface of the circuit board are at the same level or approximately at the same level; The optical fiber adapter is disposed on the second upper surface, and the optical axis of the optical fiber adapter and the optical axis of the focusing lens are in the same horizontal plane or approximately in the same horizontal plane.

7. The optical module according to claim 1, characterized in that: The port in the optical fiber adapter for inserting the optical fiber is a tapered port, and the optical fiber is inserted into the tapered port and fixed by glue.

8. The optical module according to claim 1, characterized in that: The inclination angle of the light incident surface of the optical fiber is 7°.

9. The optical module according to claim 8, characterized in that: The included angle between the central axis of the optical fiber and the optical axis of the focusing lens is 3°.

10. The optical module according to claim 1, characterized in that: The central axis of the optical fiber is parallel to the central axis of the optical fiber adapter.

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