Patent Publication Number: US-2022221667-A1

Title: Optical Module

Description:
This application claims the priority to the Application No. 202010018782.7, filed with the China National Intellectual Property Administration on Jan. 8, 2020, and the priority to the Application No. 202010018784.6, filed with the China National Intellectual Property Administration on Jan. 8, 2020, which are incorporated herein by references in their entirety. 
     FIELD OF THE INVENTION 
     This application relates to the field of optical communication technologies, and in particular, to an optical module. 
     BACKGROUND OF THE INVENTION 
     An optical module includes a printed circuit board (PCB for short), a laser disposed on the printed circuit board, a detector, driving chips for driving the laser and the detector, and other components. The components are soldered on corresponding pads of the printed circuit board. Each component may generate heat during operation. If the heat cannot be dissipated quickly, an environment temperature of the optical module may keep rising, which may deteriorate the performance of the optical module. 
     SUMMARY OF THE INVENTION 
     According to an aspect, the present disclosure provides an optical module, comprising: an upper enclosure; a lower enclosure; a circuit board disposed in a chamber enclosed by the upper enclosure and the lower enclosure; an optical chip electrically coupled to the circuit board and configured to transmit and/or receive an optical signal; a lens assembly mounted on the circuit board, wherein the lens assembly covers the optical chip and is configured to propagate a light beam; a heat dissipation structure comprising: a first heat dissipation member provided on the circuit board, wherein a portion of the first heat dissipation member is located below the lens assembly, and the other portion is located outside of the lens assembly; wherein the optical chip is attached at one end of the first heat dissipation member, and the first heat dissipation member is configured to conduct heat generated by the optical chip to outside of a coverage region of the lens assembly; a second heat dissipation member attached on the first heat dissipation member, wherein the second heat dissipation member is provided outside of the lens assembly, and is configured to receive and diffuse heat conducted by the first heat dissipation member; a third heat dissipation member embedded in intermediate layers of the circuit board, wherein a portion of the third heat dissipation member is located below the lens assembly, and the other portion is located outside of the lens assembly; and a through hole provided between the first heat dissipation member and the third heat dissipation member, penetrating a multilayer plate in the circuit board, filled with a thermally conductive material, and configured to perform heat conduction between the first heat dissipation member and the third heat dissipation member; and a thermally conductive member disposed on an upper surface of the second heat dissipation member and configured to receive heat conducted by the second heat dissipation member, wherein one end of the thermally conductive member is thermally coupled to the upper enclosure for conducting the heat to the upper enclosure. 
     According to another aspect, the present disclosure provides an optical module, comprising: an upper enclosure; a lower enclosure; a circuit board disposed in a chamber enclosed by the upper enclosure and the lower enclosure; an optical chip electrically coupled to the circuit board and configured to transmit and/or receive an optical signal; a lens assembly mounted on the circuit board, wherein the lens assembly covers the optical chip and is configured to propagate a light beam; a heat dissipation structure comprising: a first heat dissipation member provided on the circuit board, wherein a portion of the first heat dissipation member is located below the lens assembly, and the other portion is located outside of the lens assembly; wherein the optical chip is attached at one end of the first heat dissipation member, and the first heat dissipation member is configured to conduct heat generated by the optical chip to outside of a coverage region of the lens assembly; a third heat dissipation member embedded in intermediate layers of the circuit board, wherein a portion of the third heat dissipation member is located below the lens assembly, and the other portion is located outside of the lens assembly; a second heat dissipation member attached on the circuit board, wherein the second heat dissipation member is provided outside of the lens assembly, opposite to the portion of the third heat dissipation member that is located outside of the lens assembly, and configured to receive and diffuse heat conducted by the third heat dissipation member; and through holes provided between the first heat dissipation member and the third heat dissipation member and between the second heat dissipation member and the third heat dissipation member, penetrating a multilayer plate in the circuit board, filled with a thermally conductive material, and configured to perform heat conduction between the first heat dissipation member and the third heat dissipation member and between the second heat dissipation member and the third heat dissipation member; and a thermally conductive member disposed on an upper surface of the second heat dissipation member and configured to receive heat conducted by the second heat dissipation member, wherein one end of the thermally conductive member is thermally coupled to the upper enclosure for conducting the heat to the upper enclosure. 
     According to still another aspect, the present disclosure provides an optical module, comprising: an upper enclosure; a lower enclosure; a circuit board disposed in a chamber enclosed by the upper enclosure and the lower enclosure; an optical chip electrically coupled to the circuit board and configured to transmit and/or receive an optical signal; a lens assembly mounted on the circuit board, wherein the lens assembly covers the optical chip and is configured to propagate a light beam; a heat dissipation structure comprising: a first heat dissipation member provided on the circuit board, wherein a portion of the first heat dissipation member is located below the lens assembly, and the other portion is located outside of the lens assembly; wherein the optical chip is attached at one end of the first heat dissipation member, and the first heat dissipation member is configured to conduct heat generated by the optical chip to outside of a coverage region of the lens assembly; and a second heat dissipation member attached on the first heat dissipation member, wherein the second heat dissipation member is provided outside of the lens assembly, and is configured to receive and diffuse heat conducted by the first heat dissipation member; and a thermally conductive member disposed on an upper surface of the second heat dissipation member and configured to receive heat conducted by the second heat dissipation member, wherein one end of the thermally conductive member is thermally coupled to the upper enclosure for conducting the heat to the upper enclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To more clearly describe the technical solutions of the present disclosure, the accompanying drawings to be used in the embodiments will be described briefly below. Apparently, other accompanying drawings may also be derived, without an inventive effort, by one of ordinary skills in the art from these accompanying drawings. 
         FIG. 1  is a schematic diagram illustrating a connection relationship of an optical communication terminal; 
         FIG. 2  is a schematic structural diagram of an optical network terminal; 
         FIG. 3  is an overall schematic structural diagram of an optical module according to an embodiment of this application; 
         FIG. 4  is an exploded schematic structural diagram of an optical module according to an embodiment of this application; 
         FIG. 5  is a schematic diagram of an inner structure of an optical module according to an embodiment of this application; 
         FIG. 6  is a schematic diagram of another inner structure of an optical module according to an embodiment of this application; 
         FIG. 7  is an exploded schematic diagram of an inner structure of an optical module according to an embodiment of this application; 
         FIG. 8  is an exploded schematic structural diagram of a heat dissipation structure according to an embodiment of this application; 
         FIG. 9  is a partial exploded schematic structural diagram of a heat dissipation structure according to an embodiment of this application; 
         FIG. 10  is a sectional view of a circuit board according to an embodiment of this application; 
         FIG. 11  is a diagram of a heat dissipation path of a heat dissipation structure according to an embodiment of this application; 
         FIG. 12  is a longitudinal cross-sectional view of an optical module according to an embodiment of this application; 
         FIG. 13  is a schematic structural diagram illustrating an integral forming of a thermally conductive member and an upper enclosure according to an embodiment of this application; 
         FIG. 14  is a schematic structural diagram illustrating that a thermally conductive member is mounted on a circuit board according to an embodiment of this application; 
         FIG. 15  is a schematic structural diagram of connecting an upper enclosure and a circuit board by using a thermally conductive member according to an embodiment of this application; 
         FIG. 16  is a sectional view of an inner structure of a circuit board according to an embodiment of this application; and 
         FIG. 17  is another longitudinal cross-sectional view of an optical module according to an embodiment of this application. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Technical solutions in some embodiments of the present disclosure will be described clearly and completely with reference to the accompanying drawings below. Obviously, the described embodiments are merely some but not all embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure shall be included in the protection scope of the present disclosure. 
     Unless the context requires otherwise, throughout the description and the claims, the term “comprise” and other forms thereof such as the third-person singular form “comprises” and the present participle form “comprising” are construed as open and inclusive, i.e., “including, but not limited to”. In the description of the specification, the terms such as “one embodiment”, “some embodiments”, “exemplary embodiments”, “example”, “specific example” or “some examples” are intended to indicate that specific features, structures, materials, or characteristics related to the embodiment(s) or example(s) are included in at least one embodiment or example of the present disclosure. Schematic representations of the above terms do not necessarily refer to the same embodiment(s) or example(s). In addition, the specific features, structures, materials or characteristics may be included in any one or more embodiments or examples in any suitable manner. 
     Hereinafter, the terms “first” and “second” are used for descriptive purposes only, and are not to be construed as indicating or implying the relative importance or implicitly indicating the number of indicated technical features. Thus, features defined with “first” and “second” may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the term “a/the plurality of” means two or more unless otherwise specified. 
     In the description of some embodiments, the term “coupled” and “connected” and their derivatives may be used. For example, the term “connected” may be used in the description of some embodiments to indicate that two or more components are in direct physical or electrical contact with each other. For another example, the term “coupled” may be used in the description of some embodiments to indicate that two or more components are in direct physical or electrical contact. However, the term “coupled” or “communicatively coupled” may also mean that two or more components are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the contents herein. 
     The phrase “at least one of A, B and C” has the same meaning as the phrase “at least one of A, B or C”, and they both include the following combinations of A, B and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B and C. 
     The phrase “A and/or B” includes the following three combinations: only A, only B, and a combination of A and B. 
     The use of the phrase “applicable to” or “configured to” herein means an open and inclusive language, which does not exclude devices that are applicable to or configured to perform additional tasks or steps. 
     As used herein, the term “about”, “substantially” or “approximately” includes a stated value and an average value within an acceptable range of deviation of a particular value. The acceptable range of deviation is determined by a person of ordinary skill in the art, considering measurement in question and errors associated with measurement of a particular quantity (i.e., limitations of a measurement system). 
     In optical communication technology, an optical signal is used to carry information to be transmitted, and the optical signal carrying the information is transmitted to an information processing device such as a computer through an information transmission device such as an optical fiber or an optical waveguide, so as to achieve transmission of the information. Since light has a characteristic of passive transmission when being transmitted through the optical fiber or the optical waveguide, low-cost and low-loss information transmission may be achieved. In addition, a signal transmitted by the information transmission device such as the optical fiber or the optical waveguide is the optical signal, while a signal that may be recognized and processed by the information processing device such as the computer is an electrical signal. Therefore, in order to establish information connection between the information transmission device such as the optical fiber or the optical waveguide and the information processing device such as the computer, interconversion between the electrical signal and the optical signal needs to be achieved. 
     An optical module implements a function of the interconversion between the optical signal and the electrical signal in the field of optical fiber communication technology. The optical module includes an optical port and an electrical port. The optical module achieves optical communication with the information transmission device such as the optical fiber or the optical waveguide through the optical port. And the optical module achieves electrical connection with an optical network terminal (e.g., an optical modem) through the electrical port. The electrical connection is mainly to achieve power supply, transmission of an I2C signal, transmission of data information and grounding. The optical network terminal transmits the electrical signal to the information processing device such as the computer through a network cable or wireless fidelity (Wi-Fi). 
     Embodiment 1 
       FIG. 1  shows a schematic diagram illustrating a connection relationship of an optical communication terminal. As shown in  FIG. 1 , the optical communication system includes a remote server  1000 , a local information processing device  2000 , an optical network terminal  100 , an optical module  200 , an optical fiber  101  and a network cable  103 . 
     One end of the optical fiber  101  is connected to the remote server  1000 , and the other end thereof is connected to the optical network terminal  100  through the optical module  200 . The optical fiber itself may support long-distance signal transmission, such as several-kilometer (6-kilometer to 8-kilometer) signal transmission. On this basis, infinite-distance transmission may be achieved theoretically if a repeater is used. Therefore, in a typical optical communication system, a distance between the remote server  1000  and the optical network terminal  100  may typically reach several kilometers, tens of kilometers, or hundreds of kilometers. 
     One end of the network cable  103  is connected to the local information processing device  2000 , and the other end thereof is connected to the optical network terminal  100 . The local information processing device  2000  is at least one of the followings: a router, a switch, a computer, a mobile phone, a tablet computer or a television. 
     A physical distance between the remote server  1000  and the optical network terminal  100  is greater than a physical distance between the local information processing device  2000  and the optical network terminal  100 . Connection between the local information processing device  2000  and the remote server  1000  is completely by the optical fiber  101  and the network cable  103 , and connection between the optical fiber  101  and the network cable  103  is completely by the optical module  200  and the optical network terminal  100 . 
     The optical module  200  includes an optical port and an electrical port. The optical port is configured to access the optical fiber  101 , so that a bidirectional optical signal connection is established between the optical module  200  and the optical fiber  101 ; and the electrical port is configured to access the optical network terminal  100 , so that a bidirectional electrical signal connection is established between the optical module  200  and the optical network terminal  100 . Interconversion between the optical signal and the electrical signal is achieved by the optical module  200 , so that information connection between the optical fiber  101  and the optical network terminal  100  is established. For example, an optical signal from the optical fiber  101  is converted into an electrical signal by the optical module  200  and then the electrical signal is input into the optical network terminal  100 , and an electrical signal from the optical network terminal  100  is converted into an optical signal by the optical module  200  and then the optical signal is input into the optical fiber  101 . Since the optical module  200  is a tool for achieving the interconversion between the optical signal and the electrical signal, and has no function of processing data, the information does not change in the above photoelectric conversion process. 
     The optical network terminal  100  includes a housing in a substantially cuboid shape, and an optical module interface  102  and a network cable interface  104  that are disposed on the housing. The optical module interface  102  is configured to access the optical module  200 , so that the bidirectional electrical signal connection between the optical network terminal  100  and the optical module  200  is established; and the network cable interface  104  is configured to access the network cable  103 , so that a bidirectional electrical signal connection between the optical network terminal  100  and the network cable  103  is established. Connection between the optical module  200  and the network cable  103  is established through the optical network terminal  100 . For example, the optical network terminal  100  transmits an electrical signal from the optical module  200  to the network cable  103 , and transmits an electrical signal from the network cable  103  to the optical module  200 . Therefore, the optical network terminal  100 , as a master monitor of the optical module  200 , may monitor operation of the optical module  200 . In addition to the optical network terminal  100 , the master monitor of the optical module  200  may further include an optical line terminal (OLT). 
     A bidirectional signal transmission channel between the remote server  1000  and the local information processing device  2000  has been established through the optical fiber  101 , the optical module  200 , the optical network terminal  100  and the network cable  103 . 
       FIG. 2  shows a schematic diagram of a component of an optical network terminal according to an embodiment of the present disclosure. As shown in  FIG. 2 , the optical network terminal  100  has a circuit board  105 , and a cage  106  is arranged on a surface of the circuit board  105 . Electrical connectors are provided within the cage  106  for connecting to an electrical port, such as a golden finger, of the optical module. A radiator  107  with protrusions such as fins for increasing a heat dissipation area is disposed on the cage  106 . 
     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 within the cage  106 , while the optical port of the optical module is connected to the optical fiber  101 . 
     The cage  106  is arranged on the circuit board, with the electrical connector on the circuit board being enclosed in the cage, so that the cage is provided with an electrical connector disposed within. The optical module is inserted into the cage and is fixed by the cage. Heat generated by the optical module is conducted to the cage  106 , and then is dissipated via the radiator  107  on the cage. 
       FIG. 3  is an overall schematic structural diagram of an optical module according to an embodiment of this application.  FIG. 4  is an exploded schematic structural diagram of an optical module according to an embodiment of this application.  FIG. 5  is a schematic diagram of an inner structure of an optical module according to an embodiment of this application.  FIG. 6  is a schematic diagram of another inner structure of an optical module according to an embodiment of this application.  FIG. 7  is an exploded schematic diagram of an inner structure of an optical module according to an embodiment of this application. As shown in  FIG. 3  to  FIG. 7 , an optical module  200  provided in the embodiments of this application includes an upper enclosure  201 , a lower enclosure  202 , an unlocking part  203 , a circuit board  300 , a lens assembly  401 , an optical chip  406 , a fiber ribbon  403 , a heat dissipation structure  500 , and a thermally conductive member  600 . 
     The upper enclosure  201  is covered on the lower enclosure  202  to form a chamber with two openings, and an outer contour of the chamber is generally in a cuboid shape. In an embodiment of the present disclosure, the lower enclosure  202  includes a main plate and two side plates arranged at two sides of the main plate and perpendicular to the main plate; the upper enclosure  201  includes a cover plate, where the cover plate is covered on the two side plates of the lower enclosure to form the chamber; the upper enclosure  201  may further include two side walls located at two sides of the cover plate and disposed perpendicular to the cover plate. The two side walls cooperate with the two side plates such that the upper enclosure is covered on the lower enclosure  202 . 
     The two openings of the chamber may be openings at two ends opening along the same direction, or may be two openings in different directions. Openings  204  and  205  in  FIG. 3  are two openings in opposite directions, where the opening  204  is an electrical port, and golden fingers of the circuit board may extend outwardly from the electrical port  204  and be inserted into a host computer such as the optical network terminal. The other opening  205  forms an optical port, and is configured to allow accessing of an external fiber to connect an optical transceiver  400  within the optical module. The circuit board  300 , the optical transceiver  400 , and other optoelectronic devices are located in the chamber. The optical transceiver  400  includes the lens assembly  401 , the optical chip  406 , an optical interface  405 , and the fiber ribbon  403 . 
     The assembly mode in which the upper enclosure  201  cooperates with the lower enclosure  202  facilitates to arrange the circuit board  300 , the optical transceiver  400 , and other devices into the enclosure. The upper enclosure  201  and the lower enclosure  202  form an outermost packaging protective enclosure of the optical module. The upper enclosure  201  and the lower enclosure  202  are generally made of metal materials, which is conducive to electromagnetic shielding and heat dissipation. Generally, the enclosure of the optical module is not made into an integral part. Otherwise, it will be difficult to mount positioning parts and heat dissipation and electromagnetic shielding parts during assembling of the circuit board and other components, and production automation is not facilitated, either. 
     The unlocking part  203  is located at an outer wall of the lower enclosure  202  of the chamber, to realize 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. 
     The unlocking part  203  has a clamping part that matches with the cage of the host computer, and the unlocking part may be allowed to move with respect to a surface of the outer wall by pulling a rear end of the unlocking part. The optical module in inserted into the cage of the host computer, and is fixed in the cage of the host computer by the clamping part of the unlocking part. By pulling the unlocking part, the clamping part of the unlocking part moves accordingly, so that a connection relationship between the clamping part and the host computer is changed, thereby releasing a clamping relationship between the optical module and the host computer. In this way, the optical module may be pulled out of the cage of the host computer. 
     The circuit board  300  is provided with a circuit cable, electronic elements (such as a capacitor, a resistor, a transistor, or an MOS tube), a chip (such as an MCU, a laser driver chip, a limiting amplification chip, a clock data recovery CDR chip, a power management chip, or a data processing chip DSP), and the like. The electrical components of the optical module are connected according to a circuit design via circuit tracings in the circuit board, so as to achieve electrical functions such as power supply, transmission of electrical signals and optical signals, and electrical grounding. 
     The circuit board  300  is generally a rigid circuit board. The rigid circuit board may further achieve a carrying function due to a relatively hard material thereof. For example, the rigid circuit board may carry a chip stably. When the optical transceiver  400  is mounted on the circuit board  300 , stable carrying may also be provided by the rigid circuit board. The rigid circuit board may further be inserted into the electrical connector in the cage of the host computer. In an embodiment of the present disclosure, metal pins/gold fingers are formed on a surface of a rear end of the rigid circuit board, for connecting the electrical connector. These all cannot be conveniently implemented by a flexible circuit board. 
     In some optical modules, a flexible circuit board may also be used to serve as a supplement to the rigid circuit board. The flexible circuit board is generally used in cooperation with the rigid circuit board. For example, the rigid circuit board and the optical transceiver may be connected via a flexible circuit board. 
     To realize long-distance transmission and improve a transmission rate of optical communication, optical modules with  400  G have been used in this field to emit and receive light of different wavelengths. Specifically, the optical module may adopt an optical-to-electrical converter with characteristics of dual-fiber bidirectional optical signal transmission. 
       FIG. 6  is a schematic diagram of another inner structure of an optical module according to an embodiment of this application. To realize a dual-fiber bidirectional optical signal transmission, referring to  FIG. 5  and  FIG. 6 , the optical transceiver  400  includes a lens assembly  401 , a fiber ribbon  403 , an optical interface  405 , and an optical chip  406 . The optical chip  406  includes a laser and a laser driving chip, or a detector and a detector driving chip, or any one of the laser, the laser driving chip, the detector, and the detector driving chip. The two driving chips both are electrically connected to a signal circuit of the circuit board  300 . The laser driving chip drives the laser to generate an optical signal, and the optical signal is propagated to the fiber ribbon through the lens assembly. The detector driving chip drives the detector to receive the optical signal from the fiber ribbon. 
     To realize optical coupling of the optical module, the lens assembly  401  is covered on/caps the optical chip  406 . The lens assembly  401  is configured to propagate a light beam, for example, to collimate and converge light. The lens assembly  401  is coupled to the optical interface  405  via the fiber ribbon  403 . During an optical emission process, the optical signal emitted by the laser in the optical chip  406  is collimated and converged by the lens assembly  401 , and then is emitted by the fiber ribbon  403 . During an optical receiving process, an optical signal from the optical interface  405  is propagated into the fiber ribbon  403 , and then is received by the detector in the optical chip  406 . 
     To improve a transmission efficiency of the optical module, a plurality groups of optical transceivers may be further disposed in the optical module. In other words, one group of optical transceivers, two groups of optical transceivers, or three groups of optical transceivers may be included. The way to set plurality groups of optical transceivers may be same or similar to that for one group of optical transceivers. Taking setting two groups of optical transceivers as an example. A first group of optical transceivers includes a first lens assembly  401 , a first fiber ribbon  403 , and a first optical chip  406 , and a second group of optical transceivers includes a second lens assembly  402 , a second fiber ribbon  404 , and a second optical chip  407 , as shown in  FIG. 5  and  FIG. 6 . In some embodiments of this application, the second optical chip  407  is electrically connected to a signal circuit of the circuit board  300 , for receiving and emitting the optical signal. The second lens assembly  402  is connected to the optical interface  405  through the second fiber ribbon  404 . During an optical emission process, an optical signal emitted by the second optical chip  407  is emitted by the second fiber ribbon  404  after being collimated and converged by the second lens assembly  402 . During an optical receiving process, the optical signal generated by the optical interface  405  is propagated into the second fiber ribbon  404 , and then is received by the second optical chip  407 . When a plurality groups of optical transceivers are disposed, the optical chip in each group of optical transceivers may be provided with a detector, a detector driving chip, a laser driving chip, and a laser; or may be merely provided with a detector and a detector driving chip; or may be merely provided with a laser driving chip and a laser. This is determined according to actual application, and is not specifically defined in this embodiment. 
     Components such as lasers in an optical chip may generate heat during operation. If the heat cannot be dissipated quickly, an environment temperature thereof may keep rising, which may deteriorate the performance of the optical module. Thermal conductivity of an optical module is poor because both the two optical chips are covered by the lens assembly, and an outer housing of the lens assembly is made of a plastic material. To this end, to dissipate heat for the optical module and improve heat dissipation effect, a heat dissipation structure  500  and a thermally conductive member  600  are used in embodiments of this application, to conduct the heat generated by the optical chip to the upper enclosure  201  through a surface of the circuit board  300 . The upper enclosure  201  may receive the heat conducted by the thermally conductive member  600  and dissipate the same to a surrounding environment. 
     In the optical module provided in the embodiments of this application, when plurality groups of optical transceivers are disposed, heat dissipation mechanism of the plurality groups of optical transceivers is the same as the heat dissipation principle of one group of transceivers, and details are not repeatedly described herein. Moreover, description is made by only taking heat dissipation of the laser as an example. Meanwhile, for a solution for heat dissipation of the detector, and solutions for heat dissipation of the laser, the laser driving chip, the detector, and the detector driving chip, reference may be made to the solution for the heat dissipation of the laser, and details are not repeatedly described herein. 
       FIG. 7  is an exploded schematic diagram of an inner structure of an optical module according to an embodiment of this application.  FIG. 8  is an exploded schematic structural diagram of a heat dissipation structure according to an embodiment of this application.  FIG. 9  is a partial exploded schematic structural diagram of a heat dissipation structure according to an embodiment of this application.  FIG. 10  is a sectional view of a circuit board according to an embodiment of this application. Referring to  FIG. 7 ,  FIG. 8 ,  FIG. 9 , and  FIG. 10 , the heat dissipation structure  500  provided in the embodiments of this application include a first heat dissipation member  501 , a second heat dissipation member  502 , and a third heat dissipation member  503 . 
     To make one end of the first heat dissipation member  501  be extended outside of coverage region of the lens assembly  401 , and enable the heat generated by the optical chip covered by the lens assembly  401  to be diffused towards outside of the coverage region of the lens assembly  401 , the first heat dissipation member  501  is disposed on the circuit board  300 . The first heat dissipation member  501  may be attached on the surface of the circuit board  300  along a length direction of the circuit board  300 , or may be disposed within the circuit board  300 . The first heat dissipation member  501  is configured to diffuse, along the circuit board  300 , the heat generated by the optical chip  406  to outside of the coverage region of the lens assembly  401 , that is, diffuse, along the circuit board  300 , the heat generated by the laser to outside of the coverage region of the lens assembly  401 . The dissipation member  501  may be made of a material with thermal conductivity, for example, may be a copper layer or a copper block; or may be made of another material. This is not specifically defined in the embodiments. 
     The first heat dissipation member  501  is attached on the surface of the circuit board  300 . When the first heat dissipation member  501  is a copper layer, the copper lay may be attached on the surface of the circuit board  300 . A layer of copper with a thickness of about 20 microns is formed on the surface of the circuit board  300 . The heat generated by the laser is diffused along the copper layer, so that the heat is diffused from the surface of the circuit board  300  to outside of the coverage region of the lens assembly  401 . 
     The first heat dissipation member  501  may also be embedded in the circuit board  300 , where a surface of the first heat dissipation member  501  is exposed on the surface of the circuit board  300 . The circuit board  300  is provided with a groove recessed from the surface. The first heat dissipation member  501  is embedded in the groove, so that an upper surface of the first heat dissipation member  501  is exposed on an upper surface of the circuit board  300 . When the first heat dissipation member  501  is a copper block, the copper block may be embedded within the circuit board  300 . To be specific, a groove is provided along a thickness direction of the circuit board  300 , and the copper block is placed into the groove, so that an upper surface of the copper block is exposed on the upper surface of the circuit board  300 . Optionally, the circuit board  300  may also be penetrated through its thickness direction. In this case, the first heat dissipation member  501  with a copper-block structure penetrates the circuit board  300 , with the upper surface and lower surface of the copper block being exposed on the upper surface and lower surface of the circuit board  300 , respectively. In this way, heat may be dissipated along the upper and the lower surfaces of the circuit board. When the upper surface of the copper block is exposed, a portion of the heat generated by the laser is diffused along the upper surface of the copper block, and the other portion of heat is diffused downward along the copper block. Because the lower surface of the copper block is also exposed on the lower surface of the circuit board  300 , and the lower surface of the circuit board  300  is thermally coupled to the lower enclosure  202  of the optical module, the heat diffused downward may be conducted to the lower enclosure  202 , and thus heat dissipation is achieved via the lower enclosure  202 . 
     To realize heat dissipation of the optical chip, the optical chip  406  is attached on the first heat dissipation member  501 . The optical chip  406  may be wholly attached on the first heat dissipation member  501 , or merely a portion of the optical chip  406  that generates a lot of heat is attached on the first heat dissipation member  501 . In other words, only the laser and the detector that will generate a lot of heat are positioned on the first heat dissipation member  501 , while the laser driving chip and the detector driving chip are attached on the circuit board  300 . The lens assembly  401  is covered above/caps the optical chip  406 . To prevent the lens assembly  401  from affecting the heat dissipation effect, in the embodiments, the other end of the first heat dissipation member  501  extends outwardly from the coverage region of the lens assembly  401 , where the coverage region of the lens assembly  401  is the area shown by the dotted box A in  FIG. 7  and  FIG. 8 . 
     A coverage region of the first heat dissipation member  501  on the circuit board  300  is greater than the coverage region of the lens assembly  401  on the circuit board  300 . When heat is generated by the laser located at an end of the first heat dissipation member  501 , the heat is diffused along the first heat dissipation member  501 , where a diffusion direction is from right to left (see  FIG. 7 ), so that the heat is diffused from the bottom of the lens assembly  401  to outside of the lens assembly  401 . The first heat dissipation member  501  is configured to conduct the heat generated by the optical chip  406  to outside of the coverage region of the lens assembly  401 , for example, conduct the heat generated by the laser to outside of the coverage region of the lens assembly  401 . 
     In view of the above, to dissipate the heat generated by the laser located below the lens assembly  401 , in the embodiments, the end of the first heat dissipation member  501  at which the optical chip  406  is attached is located below the lens assembly  401 . In other words, the end attached with the laser is located below the lens assembly  401 . The other end of the first heat dissipation member  501  is far away from the lens assembly  401 , that is, extends outwardly from the lens assembly  401 , so that heat below the lens assembly  401  may be diffused, along the first heat dissipation member  501 , to outside of the coverage region of the lens assembly  401 , thereby facilitating heat dissipation. 
     The optical chip  406  is attached at one end of the first heat dissipation member  501 , and the lens assembly  401  is covered above/caps the optical chip  406 . In other words, the laser is attached at one end of the first heat dissipation member  501 , and the lens assembly  401  is covered above/caps the laser, while the lens assembly  401  is connected to the fiber ribbon  403 . In this way, the first heat dissipation member  501  is located below the fiber ribbon  403 . When performing heat dissipation via the first heat dissipation member  501 , that is, performing heat dissipation by conducting heat to the upper enclosure  201 , the fiber ribbon  403  is located between the upper enclosure  201  and the first heat dissipation member  501 , and a thermally conductive member  600  is further disposed between the upper enclosure  201  and the first heat dissipation member  501 . Therefore, the thermally conductive member  600  may have a positional conflict with the fiber ribbon  403 . In view of the above, the fiber ribbon  403  may interfere with a heat dissipation path of the thermally conductive member  600 . 
     Therefore, to prevent the fiber ribbon  403  from affecting heat dissipation, in the embodiments, the heat diffused to the end of the first heat dissipation member  501  that is far away from the lens assembly  401  needs to be guided to a relatively large area at two sides of the fiber ribbon  403 . Therefore, to improve heat dissipation efficiency, a second heat dissipation member  502  is used in the embodiments so that heat may be diffused in a direction away from the fiber ribbon  403 . 
     The second heat dissipation member  502  is located outside of the lens assembly  401 , is attached at the end of the first heat dissipation member  501  that is far away from the lens assembly  401 , and is configured to receive the heat conducted by the first heat dissipation member  501  and to conduct the heat toward both sides of the circuit board  300 . The second heat dissipation member  502  may be perpendicular to the first heat dissipation member  501 , or may not be perpendicular to the first heat dissipation member  501 , provided that the heat may be diffused towards both sides of the optical fiber ribbon  403 . In this case, the second heat dissipation member  502  may conduct the received heat to an area at both sides of the fiber ribbon  403 , that is, conduct the received heat to both sides of the circuit board  300  along a width direction of the circuit board  300 . 
       FIG. 11  is a diagram of a heat dissipation path of a heat dissipation structure according to an embodiment of this application. Referring to  FIG. 11 , to conduct the heat to the area at both sides of the fiber ribbon  403 , the second heat dissipation member  502 , while being attached on the first heat dissipation member  501 , further extends towards both sides of the fiber ribbon  403 . In some embodiments of this application, an intermediate portion of the second heat dissipation member  502  is attached at the end of the first heat dissipation member  501  that is far away from the lens assembly  401 . The two ends of the second heat dissipation member  502  extend towards both sides of the circuit board  300  along a direction perpendicular to the length of the first heat dissipation member  501 , so that the second heat dissipation member  502  is perpendicular to the first heat dissipation member  501 . In other words, the second heat dissipation member  502  and the first heat dissipation member  501  together form a T-shaped structure. The intermediate portion of the second heat dissipation member  502  is configured to receive the heat conducted by the first heat dissipation member  501 , and diffuse the heat towards both ends along a length direction of the second heat dissipation member  502 . 
     As the path shown in  FIG. 11  illustrated by the arrow, the heat generated by the laser is diffused from one end (the end where the optical chip  406  is attached) of the first heat dissipation member  501  to the other end (which is far away from the lens assembly  401 ); since the second heat dissipation member  502  is attached at the other end in a perpendicularly way, heat will be diffused from the intermediate portion of the second heat dissipation member  502  towards both ends, thereby increasing a heat conduction area and accelerating/improving heat diffusion. 
     To improve heat dissipation effect, the second heat dissipation member  502  may be made of a highly thermally conductive material such as a ceramic plate (ALN), copper foil, or a carbon fiber material. 
     Regarding the optical module provided in this embodiment of this application, when performing heat dissipation, the heat generated by the laser is diffused along the surface of the circuit board  300 , and is dissipated via the upper enclosure  201 . Moreover, the second heat dissipation member  502  is provided on the circuit board  300 , and is separated from the upper enclosure  201  by a certain distance. Therefore, to realize heat conduction between the second heat dissipation member  502  and the upper enclosure  201 , in this embodiment, the heat conducted by the second heat dissipation member  502  is conducted to the upper enclosure  201  via a thermally conductive member  600 , and then is dissipated by the upper enclosure  201 . 
       FIG. 12  is a longitudinal cross-sectional view of an optical module according to an embodiment of this application. Referring to  FIG. 6 ,  FIG. 8 , and  FIG. 12 , the path indicated by the arrows in  FIG. 12  is a path along which the heat is conducted from the second heat dissipation member  502  to the thermally conductive member  600  and then to the upper enclosure  201 . The thermally conductive member  600  is disposed on an upper surface of the second heat dissipation member  502 , and is configured to receive the heat conducted by the second heat dissipation member  502  and to conduct the heat in a direction away from the circuit board  300 . The upper enclosure  201  is connected to one end of the thermally conductive member  600 , and is configured to receive and dissipate the heat conducted by the thermally conductive member  600 . 
     The thermally conductive member  600  is connected between the second heat dissipation member  502  and the upper enclosure  201 , serves for conducting the heat and supporting the upper enclosure  201 . The thermally conductive member  600  may conduct heat at the circuit board  300  to the upper enclosure  201 . The upper enclosure  201  is a main heat dissipation surface of the optical module, thus realizing a better heat dissipation effect. 
     To provide the thermally conductive member  600  with a supporting function, in this embodiment, the thermally conductive member  600  is manufactured to be rigid. Moreover, the circuit board  300  is also rigid, and the second heat dissipation member  502  is laid on the circuit board  300 . When the thermally conductive member  600  is in contact with the second heat dissipation member  502 , the rigid structure of the thermally conductive member  600  is in contact with the rigid structure of the second heat dissipation member  502 , which may easily cause abrasion to the thermally conductive member  600  or the second heat dissipation member  502 . To reduce abrasion, in this embodiment, when the thermally conductive member  600  is in contact with the second heat dissipation member  502 , a thermally conductive adhesive layer  700  is disposed therebetween, thereby realizing a soft contact between the thermally conductive member  600  and the second heat dissipation member  502 . 
     The thermally conductive adhesive layer  700  is provided at both ends of the second heat dissipation member  502  and is provided between the second heat dissipation member  502  and the thermally conductive member  600 , for increasing heat conduction efficiency. The thermally conductive adhesive layer  700  may be formed of a thermally conductive adhesive with good thermal conductivity performance. Connecting the second heat dissipation member  502  and the thermally conductive member  600  via the thermally conductive adhesive may not only avoid abrasion of the second heat dissipation member  502  or the thermally conductive member  600 , but may also improve heat conduction efficiency. 
     A configuration of the thermally conductive adhesive layer  700  is determined by the configuration of the thermally conductive member  600 . If the thermally conductive member  600  is all in contact with the second heat dissipation member  502 , only one thermally conductive adhesive layer  700  may be provided to cover the entire surface of the second heat dissipation member  502 . However, if the thermally conductive member  600  is merely in contact with the two ends of the second heat dissipation member  502 , two thermally conductive adhesive layers  700  may be provided to respectively cover the two ends of the second heat dissipation member  502 , so as to connect the second heat dissipation member  502  and the thermally conductive member  600 . 
     In this embodiment, the heat generated by the optical chip  406 , such as the laser, is diffused from the bottom of the lens assembly  401  to outside of the coverage region of the lens assembly  401  via the first heat dissipation member  501  and the second heat dissipation member  502 , and is conducted to regions away from the fiber ribbon  403 . Subsequently, the heat is conducted to the upper enclosure  201  via the thermally conductive member  600 ; thus, heat dissipation is achieved by using the upper enclosure  201 . To this end, the thermally conductive member  600  may be independently adhered or mounted onto the circuit board  300 , or may be integrally formed with the upper enclosure  201  to simplify the structure of the optical module. However, no matter the thermally conductive member  600  is separately mounted onto the circuit board  300  or is integrally formed with the upper enclosure  201 , the thermally conductive member  600  in these two solutions may be designed to have a same structure, or have different structures. 
       FIG. 13  is a schematic structural diagram of integrated forming of a thermally conductive member and an upper enclosure according to an embodiment of this application.  FIG. 14  is a schematic structural diagram illustrating that a thermally conductive member is mounted on a circuit board according to an embodiment of this application.  FIG. 15  is a schematic structural diagram of connecting an upper enclosure and a circuit board via a thermally conductive member according to an embodiment of this application. 
     Referring to  FIG. 13 , the thermally conductive member  600  is integrally formed with the upper enclosure  201 . The thermally conductive member  600  is provided at a position of the upper enclosure  201  that corresponds to the second heat dissipation member  502 , so that after the thermally conductive member  600  is integrally formed with the upper enclosure  201 , one end of the thermally conductive member  600  may be connected/contacted with the upper surface of the second heat dissipation member  502 . In this case, the heat transferred by the second heat dissipation member  502  is conducted to the upper enclosure  201  through the thermally conductive member  600 , and then is dissipated via the upper enclosure  201 . 
     Referring to  FIG. 8 ,  FIG. 14 , and  FIG. 15 , when the thermally conductive member  600  is separately designed and mounted onto the circuit board  300 , to allow the fiber ribbon  403  to pass through, a notch is provided in the thermally conductive member  600 . In some embodiments of this application, the thermally conductive member  600  includes a first thermally conductive column  601 , a second thermally conductive column  602 , and a heat conduction part  603 , where a height of the heat conduction part  603  is smaller than heights of the first thermally conductive column  601  and the second thermally conductive column  602 . To get out of the way of the fiber ribbon  403 , an area for passing-through of the fiber ribbon  403  needs to be provided in the thermally conductive member  600 . To be specific, a gap/notch is formed between the first thermally conductive column  601  and the second thermally conductive column  602 , and the fiber ribbon  403  may pass through the gap/notch. To this end, the thermally conductive member  600  may have a “ ” structure. In other words, the first thermally conductive column  601 , the heat conduction part  603 , and the second thermally conductive column  602  are sequentially connected, to form a “ ” structure. 
     The first thermally conductive column  601  and the second thermally conductive column  602  are located at two ends of the heat conduction part  603 , so that a reserved gap is formed between the first thermally conductive column  601  and the second thermally conductive column  602 , for avoiding interference with the fiber ribbon  403 . The first thermally conductive column  601  is configured to connect one end of the second heat dissipation member  502  to the upper enclosure  201 . The second thermally conductive column  602  is configured to connect the other end of the second heat dissipation member  502  to the upper enclosure  201 . Thus, both the first thermally conductive column  601  and the second thermally conductive column  602  are in contact with only one end portion of the second heat dissipation member  502 . In other words, heat is conducted from one end of the second heat dissipation member  502  to the first thermally conductive column  601 , or is conducted from the other end of the second heat dissipation member  502  to the second thermally conductive column  602 . 
     However, the intermediate portion of the second heat dissipation member  502  also receives the heat transferred from the first heat dissipation member  501 . Therefore, to improve the heat dissipation effect, in the embodiments, the first thermally conductive column  601  is connected to the second thermally conductive column  602  via the heat-conducting part  603 , so that heat of the second heat dissipation member  502  may be transferred to the first thermally conductive column  601  and the second thermally conductive column  602  through the heat conduction part  603 . In this case, the heat conduction part  603  is connected to the intermediate portion of the second heat dissipation member  502 , and is configured to receive heat conducted by the intermediate portion of the second heat dissipation member  502  and diffuse the heat to both ends. 
     The heat conduction part  603  located at the intermediate portion is designed to avoid interference with the fiber ribbon  403 , and to receive heat from the intermediate portion of the second heat dissipation member  502 , where the heat is divided into two portions, one portion is diffused to the first thermally conductive column  601 , and the other portion is diffused to the second thermally conductive column  602 . In this case, the heat diffused by the second heat dissipation member  502  may be completely conducted to the upper enclosure  201  via the first thermally conductive column  601  and the second thermally conductive column  602 . 
     In some embodiments of this application, the first thermally conductive column  601  is connected to one end of the heat conduction part  603  for receiving the heat transferred by the heat conduction part  603 . A bottom surface of the first thermally conductive column  601  is attached at one end of the second heat dissipation member  502  to receive the heat that is diffused to this end by the second heat dissipation member  502 . A top surface of the first thermally conductive column  601  is connected to the upper enclosure  201  to conduct the received heat, that is conducted by the heat conduction part  603  and is conducted by one end of the second heat dissipation member  502 , to the upper enclosure  201 ; afterwards, the heat is dissipated by using the upper enclosure  201 . 
     The second thermally conductive column  602  is connected to the other end of the heat conduction part  603 , for receiving the heat transferred by the heat conduction part  603 . A bottom surface of the second thermally conductive column  602  is attached at the other end of the second heat dissipation member  502  to receive the heat that is diffused to this end by the second heat dissipation member  502 . A top surface of the second thermally conductive column  602  is connected to the upper enclosure  201  to conduct the received heat, that is conducted by the heat conduction part  603  and is conducted by the other end of the second heat dissipation member  502 , to the upper enclosure  201 ; then, the heat is dissipated via the upper enclosure  201 . 
     In other embodiments, the thermally conductive member  600  may include a heat conduction part  603  and a first thermally conductive column  601 . The heat conduction part  603  is perpendicularly connected to the first thermally conductive column  601 , to form an L-shaped structure. One end of the first thermally conductive column  601  may be thermally connected to the heat conduction part  603 , and the first thermally conductive column  601  may also extend upward at one end of the heat conduction part  603  to form an L-shaped structure. During heat conduction, the thermally conductive member  600  is provided with two sets of L-shaped structures, which are respectively located at both sides of the second heat dissipation member  502 . The two sets of L-shaped structures are symmetrically disposed in a vertical direction. The two sets of L-shaped structures may be in contact or may not be in contact with each other, and a contact portion correspondingly forms the heat conduction part  603 . For heat dissipation process of the thermally conductive member  600  in this embodiment, reference may be made to the heat dissipation process of the thermally conductive member  603  provided in the foregoing embodiments, and details are not described herein again. 
     Regarding the optical module provided in the foregoing embodiments, to dissipate the heat generated by the laser below the lens assembly  401  via the upper enclosure  201 , the first heat dissipation member  501  is provided on the surface of the circuit board  300 . One end of the first heat dissipation member  501  is attached with the laser and is located below the lens assembly  401 , and the other end is located outside the coverage region of the lens assembly  401 . In this way, the heat generated by the laser is diffused from one end to the other end. Moreover, the other end is connected with the second heat dissipation member  502  that is perpendicular to the first heat dissipation member  501 , so as to increase a heat diffusion area. The second heat dissipation member  502  is connected to the upper enclosure  201  via the thermally conductive member  600 . The second heat dissipation member  502  may conduct the heat diffused from the first heat dissipation member  501  to the upper enclosure through the thermally conductive member  600 ; afterwards, the heat is dissipated via the upper enclosure  201 , so as to realize a better heat dissipation performance. 
     To improve the heat dissipation efficiency of the optical module, the optical module provided in the embodiments of this application may also adopt a solution where heat is dissipated via the lower enclosure  202 . That is, on the basis of the structure of the optical module provided in the foregoing embodiments, heat may also be simultaneously dissipated by the upper enclosure  201  and the lower enclosure  202  of the optical module. 
     Referring to the cross-sectional view of the circuit board shown in  FIG. 10  again, to improve heat dissipation effect, on the basis of the solution provided in the foregoing embodiments where the circuit board  300  is attached with the first heat dissipation member  501  and the second heat dissipation member  502 , a third heat dissipation member  503  may be further embedded within the circuit board  300 . Regarding the optical module provided in the embodiments of this application, on the basis that the circuit board  300  is attached with the first heat dissipation member  501  and the second heat dissipation member  502 , the third heat dissipation member  503  may be further internally provided between multilayer plates of the circuit board  300 , so that both an upper surface and a lower surface of the third heat dissipation member are not exposed on the upper surface and the lower surface of the circuit board  300 . 
     The circuit board  300  includes a plurality of multilayer plates, and the third heat dissipation member  503  may occupy several intermediate layers of the circuit board  300 . For example, if the circuit board  300  includes eight multilayer plates that are numbered “first, second . . . seventh, and eighth” from one side surface to the other side surface, the third heat dissipation member  503  may be provided in the third to sixth layers in the middle, while circuits may be provided in the first, the second, the seventh, and the eighth layers. The third heat dissipation member  503  is made of a copper material, for example, a copper block. In the embodiments, the first heat dissipation member  501  is a copper layer. 
     The third heat dissipation member  503  is built in the circuit board  300 , where a portion of the third heat dissipation member  503  is located below the lens assembly  401 , and the other portion is located outside of the lens assembly  401 . The third heat dissipation member  503  may conduct heat from one side of the surface of the circuit board  300  to the other side. A coverage region of the third heat dissipation member  503  is the same as or similar to a coverage region of the first heat dissipation member  501  attached on the surface of the circuit board  300  that is provided in the foregoing embodiments, both extending from one end at which the optical chip  406  is adhered to outside of the coverage region of the lens assembly  401 . Cross-sectional areas of the first heat dissipation member  501  and the third heat dissipation member  503  may be the same or may be different; this may be determined according to specific application. 
     To diffuse the heat generated by the laser below the lens assembly  401  to outside of the coverage region of the lens assembly  401 , the third heat dissipation member  503  is provided at a position corresponding to that of the first heat dissipation member  501 . To be specific, one end of the third heat dissipation member  503  is located below one end of the first heat dissipation member  501  that is attached with the laser, and the other end of the third heat dissipation member  503  is located below the second heat dissipation member  502 . 
     When the first heat dissipation member  501  is in a copper-layer structure, and the third heat dissipation member  503  occupies several inner layers of the circuit boar  300  so that the third heat dissipation member  503  is not in direct contact with the first heat dissipation member  501 , a heat dissipation rate is relatively small. Therefore, the third heat dissipation member  503  cannot absorb the heat that is generated by the optical chip  406  and is conducted by the first heat dissipation member  501 . To this end, for the optical module provided in the embodiments of this application, in the circuit board  300 , several through holes  504  are provided in a region between the first heat dissipation member  501  and the third heat dissipation member  503 , and the heat generated by the laser is conducted from the first heat dissipation member  501  to the third heat dissipation member  503  via the through hole  504 . In this case, the heat generated by the laser is conducted along a side surface of the circuit board  300  via the first heat dissipation member  501 , and can also be absorbed by the third heat dissipation member  503 . Dissipating heat by the third heat dissipation member  503  that is with a copper-block design may improve the heat dissipation efficiency. 
     The through holes  504  penetrate the multilayer plates of the circuit board  300 , are filled with thermally conductive material, and are configured to perform heat conduction. The thermally conductive material includes a thermally conductive ceramic, aluminum foil, a carbon fiber material, or the like. For example, the through hole  504  may be provided in the first and second layers or in the seventh and eighth layers of the circuit board  300 . 
       FIG. 16  is a sectional view of an inner structure of a circuit board according to an embodiment of this application.  FIG. 17  is another longitudinal cross-sectional view of an optical module according to an embodiment of this application. Referring to  FIG. 16  and  FIG. 17 , in the circuit board  300 , through holes  504  are provided in the region between the third heat dissipation member  503  and the first heat dissipation member  501 , where the through holes  504  are located in the circuit board  300  and are connected between an upper surface of the third heat dissipation member  503  and a side surface of the circuit board  300 . The third heat dissipation member  503  and the first heat dissipation member  501  are thermally coupled through the through holes  504 , so that a heat conduction is realized between the third heat dissipation member  503  and the first heat dissipation member  501 . To be specific, the first heat dissipation member  501  conducts the heat generated by the laser to the third heat dissipation member  503  via the through holes  504 ; subsequently, the third heat dissipation member  503  diffuses the heat from one end located below the laser to outside of the coverage region of the lens assembly  401  in a longitudinal direction; afterwards, the third heat dissipation member  503  further transfers the heat back to the first heat dissipation member  501  via the through holes  504 ; the first heat dissipation member  501  conducts the heat to the second heat dissipation member  502 , and finally, heat dissipation is performed via the thermally conductive member  600  and the upper enclosure  201 . 
     In the embodiments, conduction efficiency from the first heat dissipation member  501  to the second heat dissipation member  502  is improved by the third heat dissipation member  503 . A heat dissipation path is as follows: the heat generated by the laser is absorbed by one end of the first heat dissipation member  501 , where a part of the heat is directly conducted to the other end of the first heat dissipation member  501  along the first heat dissipation member  501 , and the other part of the heat is conducted to the third heat dissipation member  503  via the through holes  504 ; this part of heat is conducted by the third heat dissipation member  503  to an end close to the second heat dissipation member  502  in a longitudinal direction; the heat is further conducted, at this end, to the first heat dissipation member  501  via the through holes  504 ; the received heat generated by the laser (including the heat directly conducted along the first heat dissipation member  501  and the heat conducted from the third heat dissipation member  503 ) is conducted from the first heat dissipation member  501  to the second heat dissipation member  502 . 
     To realize heat diffusion, the through holes  504  may be provided in all regions of the third heat dissipation member  503  that correspond to the first heat dissipation member  501 . These regions include a region of the circuit board  300  that is between the upper surface of the third heat dissipation member  503  and a lower surface of the first heat dissipation member  501 . In this case, the first heat dissipation member  501  and the third heat dissipation member  503  are thermally coupled via the through hole  504 , while the third heat dissipation member  503  and the second heat dissipation member  502  are not directly thermally connected. In addition, in other embodiments, the through holes  504  may further be provided in an end region of the third heat dissipation member  503  (the end region includes a region of the circuit board  300  that is corresponding to the optical chip  406 ) corresponding to the first heat dissipation member  501 . Meanwhile, through holes  504  may further be provided, in the circuit board  300 , in a region of the third heat dissipation member  503  that corresponds to second heat dissipation member  502 . In this case, the second heat dissipation member  502  and the third heat dissipation member  503  are thermally connected via the through holes  504 , and the third heat dissipation member  503  may directly conduct the heat conducted by the first heat dissipation member  501  to the second heat dissipation member  502 . 
     In some embodiments, through holes  504  are provided in all regions. In this case, a plurality of through holes  504  are evenly provided in the circuit board  300  between the first heat dissipation member  501  and the third heat dissipation member  503 . The heat generated by the laser is first conducted to the first heat dissipation member  501 , and the first heat dissipation member  501  conducts a part of the heat downward via the through holes  504  below the laser, and thus conducts the heat to the third heat dissipation member  503 . The first heat dissipation member  501  diffuses the other part of the heat to outside of the coverage region of the lens assembly  401  along the surface of the first heat dissipation member  501 , that is, diffuses the heat to a position at which the first heat dissipation member  501  is in contact with the second heat dissipation member  502 . Meanwhile, regarding the heat diffused along the surface of the first heat dissipation member  501 , during a process of being diffused to the second heat dissipation member  502 , may be further conducted between the first heat dissipation member  501  and the third heat dissipation member  503  via the midway through holes  504 . In view of the above, the first heat dissipation member  501  may conduct the heat in two directions that are perpendicular to each other. The third heat dissipation member  503  may receive, through the through holes  504 , heat diffused from an end portion of the first heat dissipation member  501 , as well as heat diffused from a middle portion of the first heat dissipation member  501 . The third heat dissipation member  503  conducts the received heat to an end located below the second heat dissipation member  502  in a longitudinal direction, and conducts, through the corresponding through holes  504 , the heat back to the end of the first heat dissipation member  501  that is close to the second heat dissipation member  502 . The first heat dissipation member  501  conducts all of the heat to the second heat dissipation member  502 ; the heat is further conducted to the thermally conductive member  600  by the second heat dissipation member  502 , and is finally dissipated via the upper enclosure  201 . In this way, the heat dissipation efficiency is high. In view of the above, by using the through holes  504 , bidirectional heat conduction may be achieved between the first heat dissipation member  501  and the third heat dissipation member  503  at the region where the first heat dissipation member  501  is corresponding to the third heat dissipation member  503 . 
     In some embodiments, through holes  504  are provided in an end-portion region. A plurality of through holes  504  are evenly provided, in the circuit board  300 , between the corresponding first heat dissipation member  501  and third heat dissipation member  503  below the laser. Alternatively, a plurality of through holes  504  may be evenly provided, in the circuit board  300 , corresponding to a position at which the first heat dissipation member  501  is attached with the second heat dissipation member  502 . In this case, the through holes  504  are provided at both ends of the third heat dissipation member  503 . The heat generated by the laser is first conducted to the first heat dissipation member  501 , and the first heat dissipation member  501  conducts a part of the heat downward via the through holes  504  below the laser, so that the heat is conducted to the third heat dissipation member  503 . The first heat dissipation member  501  diffuses the other part of the heat to the outside of the coverage region of the lens assembly  401  along the surface of the first heat dissipation member  501 , that is, diffuses the heat to a position at which the first heat dissipation member  501  is in contact with the second heat dissipation member  502 . When the heat is diffused to the second heat dissipation member  502 , the first heat dissipation member  501  may further conduct, via the through holes  504  in this region, a small part of the heat downward to the third heat dissipation member  503 , and diffuse the other part of the heat to the second heat dissipation member  502 , so that the heat is dissipated after being conducted to the upper enclosure  201  via the thermally conductive member  600 . In view of the above, the first heat dissipation member  501  may conduct the heat in two directions that are perpendicular to each other. The third heat dissipation member  503  may receive, via the through holes  504 , the heat diffused from both ends of the first heat dissipation member  501 . Meanwhile, the third heat dissipation member  503  may laterally conduct the received heat to an end located below the second heat dissipation member  502 , and conduct the heat to the first heat dissipation member  501  via the corresponding through holes  504 . Subsequently, the heat is conducted to the thermally conductive member  600  via the second heat dissipation member  502 , and is finally dissipated via the upper enclosure  201 . In this way, the heat dissipation efficiency is high. In view of the above, via the through holes  504 , bidirectional heat conduction may be achieved between the first heat dissipation member  501  and the third heat dissipation member  503  at the region where the first heat dissipation member  501  is corresponding to the third heat dissipation member  503 . 
     To dissipate heat via the lower enclosure  202  of the optical module, in the embodiments, when heat is dissipated via the lower enclosure  202 , the lower surface of the circuit board  300  is attached with a fourth heat dissipation member (not shown in the figure). The fourth heat dissipation member and the first heat dissipation member are respectively attached at two opposite sides of the circuit board  300 . The fourth heat dissipation member and the first heat dissipation member may have a same structure, and both have a copper-layer structure or an embedded copper-block structure. The fourth heat dissipation member is thermally coupled to the lower enclosure  202  of the optical module. Through holes  504  are provided between the fourth heat dissipation member and a lower surface of the third heat dissipation member  503 . The through holes  504  are configured to receive the heat conducted by the third heat dissipation member  503 , and to conduct the heat to the lower enclosure  202  via the fourth heat dissipation member. For example, if the through holes  504  between the first heat dissipation member  501  and the third heat dissipation member  503  are provided in the first and second multilayer plates of the circuit board  300 , through holes  504  between the third heat dissipation member  503  and the fourth heat dissipation member are provided in the seventh and eighth multilayer plates of the circuit board  300 . 
     The heat generated by the laser is conducted to the third heat dissipation member  503  via the first heat dissipation member  501  and the through holes  504  (that are located between the first heat dissipation member  501  and the third heat dissipation member  503 ). The third heat dissipation member  503  continues to conduct the heat downward to the fourth heat dissipation member through the through holes  504  (that are located between the fourth heat dissipation member and the third heat dissipation member  503 ) at the lower surface of the third heat dissipation member  503 . Further, the heat is conducted to the lower enclosure  202  by the fourth heat dissipation member, and is dissipated via the lower enclosure  202 . According to the optical module of the embodiment, the heat generated by the laser may be dissipated via both the upper enclosure  201  and the lower enclosure  202 , and thus the heat dissipation efficiency is higher. 
     When performing heat dissipation in the optical module by the first heat dissipation member  501 , the second heat dissipation member  502 , the third heat dissipation member  503 , and the fourth heat dissipation member, the first heat dissipation member  501  and the fourth heat dissipation member may be copper layers provided on the surface of the circuit board  300 , or may be copper blocks embedded in the circuit board  300 . When the first heat dissipation member  501  and the fourth heat dissipation member are copper blocks, grooves are provided on side surfaces of the circuit board  300 . To be specific, a groove is provided in the first and second layers of the circuit board  300 , or a groove may be provided in the seventh and eighth layers. The copper blocks are mounted in the grooves, and an upper surface of the copper block is exposed on the surface of the circuit board  300 . For a specific implementation solution that the first heat dissipation member  501  and the fourth heat dissipation member are copper layers or copper blocks, reference may be made to the content in the foregoing embodiments, and details are not described herein again. 
     To realize soft contact between the lower surface of the circuit board  300  and the lower enclosure  202 , a thermally conductive adhesive layer  700  is disposed between the circuit board  300  and the lower enclosure  202 . The structure and material of the thermally conductive adhesive layer  700  in the embodiments may be same as those in the foregoing embodiments, and details are not described herein again. 
     In another embodiment, different from the optical module provided in the foregoing embodiments, the first heat dissipation member  501  and the second heat dissipation member  502  are not attached together, but the second heat dissipation member  502  is thermally coupled to the third heat dissipation member  503  via the through holes  504 . The second heat dissipation member  502  is attached on the circuit board  300 , located outside of the lens assembly  401 , and is opposite to one end of the third heat dissipation member  503 . The second heat dissipation member  502  is configured to receive and diffuse the heat conducted by the third heat dissipation member. 
     In this embodiment, a coverage region of the third heat dissipation member  503  extend beyond that of the first heat dissipation member  501 . Because the first heat dissipation member  501  is not in contact with the second heat dissipation member  502 , the function of the first heat dissipation member  501  is to diffuse the heat generated by the laser attached thereon to outside of the coverage region of the lens assembly  401 , and further conduct, via the through holes  504 , the heat to the third heat dissipation member  503  provided in inner layers of the circuit board  300 , and further diffuse heat quickly by the third heat dissipation member  503 . 
     The third heat dissipation member  503  longitudinally diffuses the heat conducted received from the first heat dissipation member  501 , and conducts the heat to a position below the second heat dissipation member  502 . The through holes  504  are provided between the second heat dissipation member  502  and the third heat dissipation member  503 , and heat conduction between the second heat dissipation member  502  and the third heat dissipation member  503  is achieved via the through holes between the second heat dissipation member  502  and the third heat dissipation member  503 . The third heat dissipation member  503  conducts the heat to the second heat dissipation member  502  via the through holes  504 . Finally, heat dissipation is achieved by the thermally conductive member  600  and the upper enclosure  201 . 
     According to the optical module in the foregoing plurality of embodiments, a first heat dissipation member  501  is provided on the surface of the circuit board  300  or is provided in an embedded way. The heat generated by the laser is conducted to the upper enclosure  201  through the thermally conductive member  600  by the first heat dissipation member  501  and the second heat dissipation member  502  that are disposed on the surface of the circuit board  300 , thus realizing a heat dissipation via the upper enclosure  201 . By embedding a third heat dissipation member  503  in several intermediate/inner layers of the circuit boar  300 , the heat generated by the laser is conducted to the lower enclosure  202  via the third heat dissipation member  503  provided within/inside of the circuit board  300  and the corresponding through holes  504 , thus realizing a heat dissipation via the lower enclosure  202 . Meanwhile, the third heat dissipation member  503  longitudinally diffuses the heat received from the first heat dissipation member  501  to a position close to the second heat dissipation member  502 , and conducts the heat to the first heat dissipation member  501  again via the through holes  504 . By the first heat dissipation member  501 , the heat is all conducted to the second heat dissipation member  502 , and is finally dissipated after passing through the thermally conductive member  600  and the upper enclosure  201 . In view of the above, the optical modules provided in the embodiments of this application can all realize heat dissipation for a laser, and may have a higher heat dissipation efficiency. 
     It may be learned from the foregoing schemes, in an optical module provided in the embodiments of this application, the first heat dissipation member  501  is provided on the circuit board  300 , one end of the first heat dissipation member  501  is attached with the optical chip  406 , and the lens assembly  401  is covered on/caps the optical chip  406 . The other end of the first heat dissipation member  501  extends outwardly from the coverage area of the lens assembly  401 , so that the heat generated by the optical chip  406  is diffused from the bottom of the lens assembly  401  to outside of the lens assembly, and is conducted to a side surface of the circuit board  300 . The third heat dissipation member  503  is embedded in the intermediate layers of the circuit board  300 , with a portion positioned below the lens assembly  401  and the other portion positioned outside of the lens assembly  402 . The through holes  504 , for performing heat conduction, penetrate the multilayer plates of the circuit board  300  and are filled with a thermally conductive material. The through holes  504  are provided between the first heat dissipation member  501  and the third heat dissipation member  503  to realize a heat conduction between the first heat dissipation member  501  and the third heat dissipation member  503 . One end of the first heat dissipation member  501  that is far away from the lens assembly  401  is provided with the second heat dissipation member  502 . The upper surface of the second heat dissipation member  502  is provided with the thermally conductive member  600 , and the upper surface of the thermally conductive member  600  is thermally connected with the upper enclosure  201 . The heat conducted by the first heat dissipation member  501  and the heat diffused via the third heat dissipation member  503  is conducted to the second heat dissipation member  502  by the first heat dissipation member  501 , and is further conducted to the upper enclosure  201  via the thermally conductive member  600 , so as to achieve a heat dissipation via the upper enclosure  201 . In view of the above, according to the optical module provided in the embodiments of this application, the heat generated by the optical chip  406  covered by the lens assembly  401  may be diffused to outside of the coverage region of the lens assembly  401  by using the first heat dissipation member  501 . Moreover, a heat conduction area may be increased by the second heat dissipation member  502 , the thermally conductive member  600 , and the third heat dissipation member  503 , so that heat can be dissipated from the upper enclosure  201  with a better heat dissipation effect. 
     Finally, it should be noted that the foregoing embodiments are merely intended to describe the technical solutions of the present disclosure, and shall not be construed as limitation. Although the present disclosure is described in detail with reference to the foregoing embodiments, one of ordinary skills in the art may understand that modifications still may be made to the technical solutions disclosed in the foregoing embodiments, or equivalent replacements may be made to some of the technical features. However, these modifications or equivalent replacements do not deviate the nature of corresponding technique solutions from the spirit and scope of the technique solutions of the embodiments of the present disclosure.