Patent Publication Number: US-2020287347-A1

Title: Optical sub-module and optical module

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of PCT/CN2019/075259 filed on Feb. 15, 2019, which claims priority to Chinese Patent Application No. 201810153984.5 filed with the Chinese Patent Office on Feb. 22, 2018, titled “OPTICAL SUB-MODULE AND OPTICAL MODULE”, which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to the field of optical communication, and in particular, to an optical sub-module and an optical module. 
     BACKGROUND 
     An optical module is a device used for conversion between optical signals and electrical signals in optical communication. 
     The optical module usually includes at least one optical sub-module, and the at least one optical sub-module includes at least one of a transmitter optical sub-module, a receiver optical sub-module, or a bi-directional optical sub-module. 
     Here, the transmitter optical sub-module may also be commonly referred to as a transmitter optical sub-assembly (TOSA), which is configured to convert an electrical signal into an optical signal. The receiver optical sub-module may also be commonly referred to as a receiver optical sub-assembly (ROSA), which is configured to convert an optical signal into an electrical signal. The bi-directional optical sub-module may also be commonly referred to as a bi-directional optical sub-assembly (BOSA), which is configured to convert an electrical signal into an optical signal and convert an optical signal into an electrical signal. 
     SUMMARY 
     In one aspect, embodiments of the present application provide an optical sub-module. The optical sub-module includes a base body having a first base surface and a second base surface that are opposite to each other, a plurality of pins each penetrating through the second base surface and the first base surface, a heat sink disposed on the first base surface and including a groove facing the plurality of pins, a temperature regulator disposed in the groove, and a light emitter disposed on the temperature regulator. The temperature regulator includes a first heat exchange surface and a second heat exchange surface that are opposite to each other, the first heat exchange surface is in contact with an inner wall of the groove, and the light emitter is disposed at the second heat exchange surface and configured to perform heat transfer with the temperature regulator. 
     In another aspect, the embodiments of the present application further provide an optical module. The optical module includes a circuit board and at least one optical sub-module described above disposed on the circuit board. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to explain the technical solutions in the embodiments of the present application more clearly, the accompanying drawings used in the description of the embodiments will be introduced briefly. The accompanying drawings to be described below show some illustrative embodiments of the application, and a person of ordinary skill in the art may obtain other drawings according to those drawings without paying any creative effort. 
         FIG. 1  is a schematic diagram showing a structure after a distributed feedback (DFB) laser and a cooler are packaged by using transistor-outline (TO) packaging technology; 
         FIG. 2  is a schematic diagram showing an overall structure of an optical sub-module, in accordance with some embodiments of the present disclosure; 
         FIG. 3  is a schematic diagram showing a structure of a casing assembly in an optical sub-module and an inner structure of the optical sub-module after the casing assembly is removed, in accordance with some embodiments of the present disclosure; 
         FIG. 4  is a schematic diagram showing an internal structure of an optical sub-module, in accordance with some embodiments of the present disclosure; 
         FIG. 5  is a schematic exploded diagram of partial structures in the optical sub-module shown in  FIG. 4 ; 
         FIG. 6  is a schematic exploded diagram of an internal structure of the optical sub-module shown in  FIG. 4 ; 
         FIG. 7  is a schematic diagram showing an overall structure in which a heat sink is mounted on a base body in an optical sub-module, in accordance with some embodiments of the present disclosure; 
         FIG. 8  is a top view of the heat sink and the base body in the optical sub-module shown in  FIG. 7 ; 
         FIG. 9  is a schematic diagram showing a structure of a temperature regulator and a structure of a light emitter in an optical sub-module, in accordance with some embodiments of the present disclosure; 
         FIG. 10  is a schematic diagram showing a structure in which metal wires are connected to pins and corresponding functional devices in an optical sub-module, in accordance with some embodiments of the present disclosure; and 
         FIG. 11  is a schematic diagram showing a structure of an optical module, in accordance with some embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The technical solutions in some embodiments of the present disclosure will be clearly and completely described below in combination with the accompanying drawings. However, 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 on the basis of the embodiments of the present disclosure shall be included in the protected scope of the present disclosure. 
     Unless the context otherwise requires, in the entire specification and the claims, the term “comprise” and other forms 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, terms “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 the 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 same embodiment(s) or example(s). 
     In addition, the specific features, structures, materials, or characteristics may be included in any or more embodiments or examples in any suitable manner. Terms such as “first” and “second” are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features below. Therefore, features defined as “first” or “second” may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, the term “plurality” means two or more unless otherwise specified. 
     In the description of some embodiments, the terms such as “connected”, “coupled”, or their extensions 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 terms such as “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. For example, the terms such as “coupled” or “communicatively coupled” may also mean that two or more components are not in direct contact with each other but are in indirect contact through one or more other elements disposed therebetween. The embodiments disclosed herein are not necessarily limited to the contents herein. 
     To make the purpose, the technical solutions, and advantages of the present disclosure clearer, the embodiments of the present disclosure will be described in further detail below in combination with the accompanying drawings. 
     A laser is an important optoelectronic device in an optical sub-module. For example, a distributed feedback (DFB) laser is widely used in the field of optical communication because it has a good monochromaticity (i.e., a high spectral purity) and may be used to transmit data signals. 
     The development and maturing of international telecommunication standard 5th generation wireless systems (5G) is driving a large increase in data flow rates in data centers, and transmission rates of lasers in such data centers are continuously increased to support the higher data flow rates. In the related art, a transmission rate of the DFB laser may reach, for example, 25 Gbit/s, 40 Gbit/s, or even 100 Gbit/s. A DFB laser with a transmission rate of 25 Gbit/s has become an important component of equipment used to achieve the international telecommunication standard 5G and the data center. 
     According to different operating temperatures, the DFB lasers may generally be divided into the following three types: a commercial-grade DFB laser, an industrial-grade DFB laser, and an extended-grade DFB laser. 
     Taking DFB lasers of different types and with transmission rates of 25 Gbit/s as an example, an operating temperature of the commercial-grade DFB laser is within a range from −5° C. to 75° C., inclusive, an operating temperature of the industrial-grade DFB laser is within a range from −40° C. to 85° C., inclusive (or even within a range from −40° C. to 95° C., inclusive), and an operating temperature of the extended-grade DFB laser is within a range from −5° C. to 85° C., inclusive (or even within a range from −5° C. to 95° C., inclusive). 
     A manufacturing process of the commercial-grade DFB laser is very simple. Therefore, there are a large number of commercial-grade DFB lasers in the market. An industrial-grade high-speed (referring to a transmission rate of 25 Gbit/s and above) DFB laser is very difficult to manufacture and has a low yield. Therefore, a price of the industrial-grade high-speed DFB laser is very high, and is usually 1.5-2 times a price of the commercial-grade DFB laser. 
     In a scenario in which a range of an operating temperature corresponds to the range of the operating temperature of the industrial-grade DFB laser, the industrial-grade DFB laser with a transmission rate of 25 Gbit/s needs to be used. Alternatively, either of the following two solutions can be used: 
     1) the industrial-grade DFB laser could be used without a cooler packaged therewith, but technology for manufacturing this kind of DFB laser is immature, and a price thereof is high, which make mass production and mass use of such lasers difficult to achieve; and 
     2) the commercial-grade DFB laser or the extended-grade DFB laser could be used, and the temperature of the commercial-grade DFB laser or the extended-grade DFB laser may be controlled to remain within the operating temperature range of the commercial-grade DFB laser by using a cooler such as a thermoelectric cooler (TEC). 
     Although the commercial-grade DFB laser or the extended-grade DFB laser, which has low price than the industrial-grade DFB, is used in the second solution, an application scope of the second solution is limited due to the need for a complex packaging process and a resultantly high packaging cost of the optical sub-module including the TEC. 
     In addition, transistor-outline (TO) packaging technology presents advantages of miniaturization, low cost, simple packaging process, and easy industrial mass production. 
     Therefore, in a case where the above second solution is adopted, the TO packaging technology may be used to package the cooler and the DFB laser. 
     Specifically,  FIG. 1  is a schematic diagram showing a structure after the DFB laser and the cooler are packaged by using the TO packaging technology. The cooler  104  is disposed on a coaxial base  102 , a heat sink  103  is disposed on the cooler  104 , and the DFB laser  101  is disposed on a side wall of the heat sink  103 . 
     Heat generated by the DFB laser  101  can only be transferred to the cooler  104  through the heat sink  103 . Therefore, a heat dissipation effect of the DFB laser  101  is not good, and further the operating temperature of the DFB laser is difficult to be controlled within the operating temperature range required by the commercial-grade DFB laser. 
     In contrast to the TO packaged embodiment of  FIG. 1 , embodiments of the present disclosure described in relation to  FIGS. 2-11  provide an optical sub-module including a base body, a plurality of pins, a heat sink, a temperature regulator, and a light emitter. 
     The base body includes a first base surface and a second base surface that are opposite to each other. A plurality of pins penetrate the second base surface and the first base surface from the second base surface to the first base surface. The heat sink is disposed on the first base surface and includes a groove facing the plurality of pins. The temperature regulator is disposed in the groove, the temperature regulator includes a first heat exchange surface and a second heat exchange surface that are opposite to each other, and the first heat exchange surface is in contact with an inner wall of the groove. The light emitter is disposed at the second heat exchange surface and is configured to perform heat transfer with the temperature regulator. 
       FIG. 4  is a schematic diagram showing an overall structure of an optical sub-module, in accordance with some embodiments of the present disclosure. As shown in  FIG. 4 , the optical sub-module  10  includes the base body  11 , the plurality of pins  12 , the heat sink  13 , the temperature regulator  14 , and the light emitter  15 . 
     As shown in  FIG. 4 , the base body  11  includes the first base surface  112  and the second base surface  111  that are opposite to each other. For convenience of description, the first base surface  112  is referred to as a top face  112 , and the second base surface  111  is referred to as a bottom face  111  hereinafter. The base body  11  may have various shapes. For example, the base body  11  may have a cylindrical shape or a prismatic shape. 
     As shown in  FIG. 4 , each of the plurality of pins  12  extends through the base body  11  to penetrate both the bottom face  111  and the top face  112 . As such, there are a plurality of pin holes in one-to-one correspondence with the plurality of pins  12  in the base body  11 , and two opposite openings of each pin hole are respectively disposed in the bottom face  111  and the top face  112 . As a result, each pin  12  inserted into a corresponding pin hole penetrates the bottom face  111  and the top face  112  of the base body  11  from the bottom face  111  to the top face  112 . 
     Furthermore, the plurality of pins  12  may be fixed on the base body  11  in a plurality of ways. For example, after each pin  12  passes through the corresponding pin hole, the pin  12  is fixed on at least one of the bottom face  111  or the top face  112  of the base body  11  through soldering. 
     Here, in order to facilitate an electrical connection between the plurality of pins  12  and the light emitter  15 , the plurality of pins  12  are disposed at a same side of the heat sink  13 . 
     As shown in  FIG. 4 , the heat sink  13  is disposed on the top face  112 , and the heat sink  13  includes the groove  131  facing the plurality of pins  12 . For example, the heat sink  13  may be made of an alloy, such as a nickel-based alloy (or an iron-based alloy), or a copper alloy. 
     In some embodiments of the present disclosure, the heat sink  13  and the base body  11  may be an integrated structure. 
     In some other embodiments of the present disclosure, the heat sink  13  and the base body  11  are separate structures, and the heat sink  13  is mounted on the top face  112  of the base body  11 . 
     In some embodiments of the present disclosure, as shown in  FIGS. 4 and 6-8 , the groove  131  may be disposed so as to extend in a direction perpendicular to the top face  112 . 
     As shown in  FIGS. 4 and 6 , the temperature regulator  14  is disposed in the groove  131 . The temperature regulator  14  includes the first heat exchange surface  141  and the second heat exchange surface  142 . The first heat exchange surface  141  is in contact with one or more inner wall(s) of the groove  131  of the heat sink  13  to absorb heat of the temperature regulator  14 , thereby dissipating the heat of the temperature regulator  14 . 
     Here, the first heat exchange surface  141  may contact the groove  131  of the heat sink  13  in a plurality of ways. For example, the first heat exchange surface  141  can be in partial contact with or can be fully attached to a bottom wall of the groove  131  located at a bottom of the groove. For another example, the first heat exchange surface  141  can be in partial contact with or can be fully attached to both side walls of the groove  131  disposed on opposite sides of the bottom wall. For yet another example, the first heat exchange surface  141  can be in partial contact with or can be fully attached to the bottom wall of the groove  131 , and can further be in partial contact with or fully attached to both side walls of the groove  131 . The embodiments of the present disclosure are not limited to the particular embodiments described herein, and can more generally have structures that provide for the heat of the temperature regulator  14  to be dissipated by contacting the groove  131  of the heat sink  13 . 
     The groove  131  penetrates (or extends to) a lower surface of the heat sink  13  and an upper surface of the heat sink  13 , and extends from the lower surface of the heat sink  13  to the upper surface of the heat sink  13 . A depth of the groove  131  is matched with a thickness of the temperature regulator  14  to ensure that an entirety of the temperature regulator  14  is embedded into the groove  131 . For example, as shown in  FIG. 6 , the term “depth of the groove” refers to a dimension of the groove  131  along the Y-axis direction, and a thickness of the temperature regulator  14  refers to a dimension of the temperature regulator  14  along the Y-axis direction. For convenience of description, a direction pointing from the bottom face  111  to the top face  112  is an upward direction (or Z direction, in  FIG. 6 ). That is, word “upper” in the term “upper surface” takes this direction as reference. Conversely, a direction pointing from the top face  112  to the bottom face  111  is a downward direction (or −Z direction, in  FIG. 6 ). That is, word “lower” in the term “lower surface” takes this direction as reference. 
     As shown in  FIG. 4 , the light emitter  15  is disposed at the second heat exchange surface  142  and is configured to perform heat transfer with the temperature regulator  14 . 
     In some embodiments of the present disclosure, as shown in  FIG. 4 , the optical sub-module  10  further includes a substrate  151  disposed on the second heat exchange surface  142 , and the light emitter  15  is disposed on the substrate  151 . For example, the light emitter  15  is disposed on a surface of the substrate  151  that faces away from the second heat exchange surface  142 . 
     In some other embodiments of the present disclosure, the light emitter  15  is disposed on the second heat exchange surface  142  of the temperature regulator  14 . That is, in such other embodiments, the light emitter  15  is directly attached to the second heat exchange surface  142 . 
     In some embodiments of the present disclosure, the light emitter  15  includes a DFB laser. 
     In some embodiments of the present disclosure, as shown in  FIG. 5 , the substrate  151  includes a substrate body  1511  and a conductive layer  1512  disposed on the substrate body  1511 . The substrate body  1511  includes a first body surface  1513  and a second body surface  1514  that are opposite to each other. The conductive layer  1512  includes a first conductive layer surface  15121  and a second conductive layer surface  15122  that are opposite to each other. The first conductive layer surface  15121  is in contact with the second body surface  1514 , and the second conductive layer surface  15122  is in contact with the light emitter  15 . The substrate body  1511  is made of a material having thermal conductivity and insulativity, such as ceramic or plastic. The conductive layer  1512  may be, a metal layer, and is made of, for example, gold. 
     As shown in  FIG. 6 , the second heat exchange surface  142  is configured to be in contact with the first body surface  1513 . The second body surface  1514  is more proximate to a central axis  19  of the base body  11  than the first body surface  1513 . The central axis  19  penetrates the top face  112  and the bottom face  111 . In this way, the above structures on the top surface  112  may be distributed uniformly. 
     It will be seen that, in the embodiments of the present disclosure depicted in the figures, the first heat exchange surface  141  of the temperature regulator  14  is in direct contact with the heat sink  13 . In this case, on one hand, the heat generated by the temperature regulator  14  is quickly dissipated through the heat sink  13 . On another hand, the light emitter  15  is disposed at the second heat exchange surface  142  of the temperature regulator  14 . For example, the light emitter  15  can be disposed on the second heat exchange surface  142  of the temperature regulator  14 , or the light emitter  15  can be disposed on the substrate  151  on the second heat exchange surface  142  of the temperature regulator  14 , thereby ensuring an efficient heat transfer between the light emitter  15  and the temperature regulator  14 , and improving a heat transfer efficiency between the light emitter  15  and the temperature regulator  14 . Furthermore, the heat received or generated by the temperature regulator  14  may be directly dissipated through the heat sink  13 , which further improves a heat dissipation rate of the light emitter  15 . 
     Through the above setting manner, an operating temperature of the light emitter  15  may be effectively controlled within the operating temperature range required by the commercial-grade DFB laser (for example, from −5° C. to 75° C., inclusive), which meets the heat dissipation requirement for the DFB laser in the second solution. 
       FIG. 7  is a schematic diagram showing an overall structure in which the heat sink  13  is mounted on the base body  11  in some embodiments of the present disclosure.  FIG. 8  is a top view of the heat sink  13  and the base body  11  shown in  FIG. 7 . As shown in  FIGS. 7 and 8 , the heat sink  13  includes a heat sink body  132  and two side arms (i.e., a first side arm  133   a  and a second side arm  133   b ) extending from a same side of the heat sink body  132  and disposed on opposite sides of the groove  131 . As shown in  FIG. 8 , the heat sink body  132  and the two side arms  133   a  and  133   b  form the groove  131  together, so that the heat sink  13  is a U-shaped structure as a whole. An opening (i.e., the groove  131 ) of the U-shaped structure faces the plurality of pins  12 . 
     Here, the heat sink body  132  and the two side arms form the groove  131  together. That is, an inner side wall  1331  of each side arm  133   a  and  133   b  is a side wall of the groove  131 , and an inner side wall  1321  of the heat sink body  132  is the bottom wall of the groove  131 . 
     It will be seen from the foregoing description that the heat sink  13  is configured to dissipate the heat of the temperature regulator  14 , and because the temperature regulator  14  is disposed in the groove  131  of the heat sink  13 , the heat sink  13  is further configured to accommodate the temperature regulator  14 . 
     In some embodiments of the present disclosure, as shown in  FIG. 6 , the optical sub-module  10  further includes an insulating plate  17  disposed on an end face  1332  of each side arm  133   a  and  133   b , and a conductive trace  171  disposed on a surface of the insulating plate  17  facing the plurality of pins  12 . For example, the insulating plate  17  may be a plate-type structure having thermal conductivity and insulativity, such as a ceramic plate. 
     That is, two insulating plates  17  can be distributed on respective sides of the substrate  151 . Here, the end face  1332  of each side arm refers to a surface of the side arm facing the plurality of pins  12 . 
     In some embodiments of the present disclosure, as shown in  FIGS. 6 and 10 , the insulating plates  17  on the end faces of the two side arms are parallel or approximately parallel to each other. In this case, patterns of the conductive traces  171  on the two insulating plates  17  are mirror-symmetrical. 
     In some embodiments of the present disclosure, as shown in  FIGS. 3 and 4 , the plurality of pins  12  include a first pin  121   a  and a second pin  121   b  that are configured to transmit high-frequency signals. 
     As shown in  FIGS. 4, 6 and 7 , in the two side arms  133   a  and  133   b  of the heat sink  131 , a conductive trace  171  corresponding to an end face  1332  of the first side arm  133   a  is configured to be electrically connected to the first pin  121   a  and to the light emitter  15 . For convenience of connection, the first pin  121   a  may be a pin of the plurality of pins  12  proximate to the conductive trace  171 . A conductive trace  171  corresponding to an end face  1332  of the second side arm  133   b  is configured to be electrically connected to the second pin  121   b  and to the light emitter  15 . Similarly, for convenience of connection, the second pin  121   b  may be a pin  12  of the plurality of pins  12  proximate to the other conductive trace  171 . 
     That is to say, the conductive trace  171  corresponding to each side arm  133   a  or  133   b  is electrically connected to a nearby pin  121   a  or  121   b  for transmitting a high-frequency signal. 
     The conductive trace  171  may be a metal strip coated on the insulating plate  17 , such as a micro-strip line. An impedance of the micro-strip line may be 25 ohms or 50 ohms. A surface of the micro-strip line is plated with gold. The micro-strip line may be electrically connected to metal wires by using a gold wire bonding process. 
     In some embodiments of the present disclosure, as shown in  FIG. 9 , the temperature regulator  14  includes the first heat exchange surface  141 , the second heat exchange surface  142 , and a plurality of semiconductor structures  143  spaced apart from each other between the first heat exchange surface  141  and the second heat exchange surface  142 . 
     The plurality of semiconductor structures  143  may include at least one N-type semiconductor structure and at least one P-type semiconductor structure. 
     A cold end of the N-type semiconductor structure after being energized is on a same side as a cold end of the P-type semiconductor structure after being energized. Correspondingly, a hot end of the N-type semiconductor structure after being energized is on a same side as a hot end of the P-type semiconductor structure after being energized. 
     In some examples, the at least one N-type semiconductor structure includes a plurality of N-type semiconductor structures and the at least one P-type semiconductor structure includes a plurality of P-type semiconductor structures. The plurality of N-type semiconductor structures and the plurality of P-type semiconductor structures may be arranged in a two-dimensional array, and may be alternately arranged in both a row direction and a column direction of the array, and all the N-type semiconductor structures and all the P-type semiconductor structures may be connected in series. A connection point between an N-type semiconductor structure and a P-type semiconductor structure is proximate to one heat exchange surface of the temperature regulator  14 , and the other connection point therebetween is proximate to the other heat exchange surface of the temperature regulator  14 . 
     For example, each N-type semiconductor structure may extend between the first heat exchange surface  141  and the second heat exchange surface  142 , and each P-type semiconductor structure may similarly extend between the first heat exchange surface  141  and the second heat exchange surface  142 . Moreover, in situations in which the first heat exchange surface  141  is warmer relative to the second heat exchange surface  142 , the end of each of the N-type and P-type semiconductor structures extended to the first heat exchange surface  141  may be referred to as a hot end and the opposite end of each of the N-type and P-type semiconductor structures extended to the second heat exchange surface  141  may be referred to as a cold end. Conversely, in situations in which the first heat exchange surface  141  is colder relative to the second heat exchange surface  142 , the end of each of the N-type and P-type semiconductor structures extended to the first heat exchange surface  141  may be referred to as a cold end and the opposite end of each of the N-type and P-type semiconductor structures extended to the second heat exchange surface  141  may be referred to as a hot end. Additionally, conductive structures (e.g., conductive plates or conductive traces) may be provided on each of the first and second heat exchange surfaces  141  and  142  to electrically connect ends of N-type and P-type semiconductor structures to each other such that the N-type and P-type semiconductor structures are connected in series. 
     As shown in  FIG. 9 , in some embodiments of the present disclosure, the temperature regulator  14  further includes a first electrode  144   a  and a second electrode  144   b . As shown in  FIG. 10 , the plurality of pins  12  further include a third pin  121   c  and a fourth pin  121   d  that are configured to be connected to an external power supply. The first electrode  144   a  and the second electrode  144   b  are configured to be electrically connected to the third pin  121   c  and the fourth pin  121   d , respectively. 
     Here, as shown in  FIG. 9 , the first electrode  144   a  and the second electrode  144   b  may be prismatic electrodes. That is, one prismatic electrode  144   a  is configured to be connected to a positive electrode of the power supply, and the other prismatic electrode  144   b  is configured to be connected to a negative electrode of the power supply. 
     With continued reference to  FIG. 10 , the prismatic electrode  144   a  and the prismatic electrode  144   b  may be electrically connected to the third pin  121   c  and the fourth pin  121   d  by using the metal wires or a conductive silver adhesive. In this way, the prismatic electrode  144   a  and the prismatic electrode  144   b  are electrically connected to the power supply through the third pin  121   c  and the fourth pin  121   d.    
     In a case where the prismatic electrode  144   a  and the prismatic electrode  144   b  are electrically connected to the power supply, the N-type semiconductor structures and the P-type semiconductor structures are connected to form a loop together. For example, the N-type semiconductor structures and the P-type semiconductor structures are connected in series with each other between the prismatic electrodes  144   a  and  144   b  such that a current flowing from one prismatic electrode to the other prismatic electrode flows through the series-connected N- and P-type semiconductor structures. A temperature of a connection point between an N-type semiconductor structure and a P-type semiconductor structure that are adjacent and connected, which is proximate to one heat exchange surface of the temperature regulator  14  gets high, while a temperature of the other connection point therebetween proximate to the other heat exchange surface of the temperature regulator  14  gets low, such that one of the first heat exchange surface  141  and the second heat exchange surface  142  of the temperature regulator  14  is a hot end face, and the other thereof is a cold end face. 
     It will be understood that, the hot end face and the cold end face are presented in the case where the prismatic electrode  144   a  and the prismatic electrode  144   b  are electrically connected to the power supply. In a case where an energization direction of the electrodes is changed, the hot end face may also be changed to a cold end face, and correspondingly the cold end face may also be changed to a hot end face. 
     In some embodiments of the present disclosure, the temperature regulator  14  may function as a thermoelectric cooler, i.e., a TEC cooler. 
     It will be understood that, in one energization direction, the first heat exchange surface  141  is the hot end face, and the second heat exchange surface  142  is the cold end face. In another energization direction, by changing the polarity of electrodes of the power supply connected to the prismatic electrode  144   a  and the prismatic electrode  144   b , a direction of currents may be changed in the N-type semiconductor structures and the P-type semiconductor structures that are connected in series. In this way, the first heat exchange surface  141  may be changed to the cold end face, and the second heat exchange surface  142  may be changed to the hot end face. 
     The light emitter  15  is disposed at the second heat exchange surface  142 . Therefore, in a case where the operating temperature of the light emitter  15  is greater than a maximum temperature (for example, 75° C.), the energization direction of the electrodes is changed, such that the direction of the currents in the N-type semiconductor structures and the P-type semiconductor structures that are connected in series is changed. In this way, the second heat exchange surface  142  is the cold end face, and heat of the light emitter  15  may be transferred to the second heat exchange surface  142  to lower a temperature of the light emitter  15 . 
     Similarly, in a case where the operating temperature of the light emitter  15  is less than a minimum temperature (for example, −5° C.), the energization direction of the electrodes is changed, such that the direction of the currents in the N-type semiconductor structures and the P-type semiconductor structures that are connected in series is changed. In this way, the second heat exchange surface  142  is changed to the hot end face, and heat of the second heat exchange surface  142  may be transferred to the light emitter  15  to increase the temperature of the light emitter  15 . 
     It will be seen that, by selectively switching the second heat exchange surface  142  of the temperature regulator  14  to be the cold end face or the hot end face, the temperature of the light emitter  15  may be maintained within the required operating temperature range in both hot and cold environments, respectively. That is to say, through a temperature regulating function of the temperature regulator  14 , the light emitter  15  may be maintained within its narrow operating temperature range of which is narrow even in situations in which requirements for the temperature range are high. For example, a commercial-grade light emitter, an operating temperature of which is within a range from −5° C. to 75° C., inclusive, can be used in an industrial scenario in which an operating temperature varies within a range from −40° C. to 95° C., inclusive, through use of the temperature regulator  14 . Although the operating temperature of the light emitter may vary widely in the industrial scenario, through the temperature regulating function of the temperature regulator  14 , the operating temperature of the commercial-grade light emitter may still be controlled so as to be maintained within the operating temperature range of the commercial-grade light emitter and thereby meet the requirements of industrial use. 
     In some embodiments of the present disclosure, a distance between the cold end face and the hot end face of the temperature regulator  14  (i.e., a distance between the first heat exchange surface  141  and the second heat exchange surface  142 ) is approximately equal to the depth of the groove  131  of the heat sink  13  (i.e., a dimension along the Y-axis direction in  FIG. 6 ), which enables the entire temperature regulator  14  to be embedded into the groove  131 . 
     As shown in  FIG. 5 , the substrate body  1511  further includes a substrate side surface  1515  connecting and abutting both the first body surface  1513  and the second body surface  1514 , and disposed to face away from the top face  112 . As shown in  FIGS. 5, 7, and 10 , the second body surface  1514  and the surface of the insulating plate  17  on which the conductive trace  171  is disposed are in a same plane (i.e., coplanar), and the substrate side surface  1515  and a surface of the heat sink body  132  facing away from the top face  112  are in a same plane (i.e., coplanar). 
     As shown in  FIG. 10 , the optical sub-module  10  further includes a plurality of groups of metal wires  18 . The conductive layer  1512  further includes a plurality of functional portions that are insulated from each other (e.g., spaced apart from each other), such as a first functional portion  152 , a second functional portion  153 , and a third functional portion  154  shown in  FIG. 10 . 
     Here, in some examples, there is one metal wire in a group of metal wires  18 ; and in some other examples, there are a plurality of metal wires spaced apart in a group of metal wires  18 . The embodiments of the present disclosure do not limit the number of metal wires in each group of metal wires  18 , as long as two elements connected through a group of metal wires  18  may be electrically connected. For example, the number of metal wires in each group of metal wires may be adjusted according to parameters such as sizes of elements to be connected. 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the first functional portion  152  includes a first functional sub-portion  1521  and a second functional sub-portion  1522 . 
     The first functional sub-portion  1521  is in contact with one of a P-electrode and an N-electrode of the light emitter  15  disposed on the first functional sub-portion  1521 . The first functional sub-portion  1521  is disposed adjacent to a conductive trace  171  corresponding to the end face of the first side arm  133   a , and is electrically connected to the conductive trace  171  corresponding to the end face of the first side arm  133   a  through a corresponding one of the plurality of groups of metal wires  18 . The second functional sub-portion  1522  is electrically connected to the other of the P-electrode and the N-electrode of the light emitter  15  through a corresponding one of the plurality of groups of metal wires  18 . The second functional sub-portion  1522  is disposed adjacent to a conductive trace  171  corresponding to the end face of the second side arm  133   b , and is electrically connected to the conductive trace  171  corresponding to the end face of the second side arm  133   b  through a corresponding one of the plurality of groups of metal wires  18 . 
     For example, the first functional sub-portion  1521  and the second functional sub-portion  1522  are micro-strip lines formed through a gold plating process. 
     Therefore, the first pin  121   a  and the second pin  121   b  for transmitting the high-frequency signals may be electrically connected to the light emitter  15  by being respectively connected to the conductive traces  171  on the insulating plates  17 . The first pin  121   a  is electrically connected to the light transmitter  15  through a conductive trace  171  adjacent to the first pin  121   a  on one insulating plate  17 , one group of wires  18 , and the first functional sub-portion  1521 . The second pin  121   b  is electrically connected to the light emitter  15  through a conductive trace  171  adjacent to the second pin  121   b  on the other insulating plate  17 , another group of metal wires  18 , and the second functional sub-portion  1522 . Since the conductive traces  171  and the functional sub-portions connected thereto are disposed adjacent to each other, the metal wires  18  for connecting the conductive traces  171  to the functional sub-portions are very short. In this case, because a situation in which long metal wires are used to directly connect the pins  121  to the light emitter  15  is effectively avoided, a probability of coupling between the high-frequency signals and other adjacent components may be reduced, and a transmission quality of the high-frequency signals may be improved. 
     A group of metal wires  18  may be used to connect each conductive trace  171  to a corresponding functional sub-portion (the first functional sub-portion  1521  or the second functional sub-portion  1522 ) through the gold wire bonding process. 
     In some embodiments of the present disclosure, the light emitter  15  may be a distributed feedback (DFB) laser. The light emitter  15  includes a P-N junction between the P-electrode and the N-electrode. 
     One of the P-electrode and the N-electrode of the light emitter  15  is in direct contact with the first functional sub-portion  1521 , and thereby is electrically connected to the first functional sub-portion  1521 . The other of the P-electrode and the N-electrode of the light emitter  15  is electrically connected to the second functional sub-portion  1522  through a group of metal wires  18 . 
     In a case where a current injected into the P-N junction of the light emitter  15  reaches a threshold current, the P-N junction generates a laser beam. 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the light emitter  15  may be attached to the first functional sub-portion  1521  through the conductive silver adhesive or eutectic solder, and is proximate to an upper side of the substrate  151  (i.e., proximate to the substrate side surface  1515 ). Here, word “upper” in the term “upper side” refers to a direction pointing from the first base surface  112  to the second base surface  111  as reference. 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the light emitter  15  includes a light-emitting strip  1551  at a middle position. An axis of the light-emitting strip  1551  almost coincides with the central axis  19  of the base body  11 . For example, a central axis of the light-emitting strip  1551  extending in the vertical direction may be aligned with the central axis  19 , and may be collinear with the central axis  19 . 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the optical sub-module  10  further includes a temperature sensor  157  disposed on the second functional portion  153 . 
     For example, the temperature sensor  157  includes a thermistor. The temperature sensor  157  may be attached to a surface of the second functional portion  153  facing the central axis  19  of the base body  11  (i.e., the second conductive layer surface  15122 ) through the conductive silver adhesive or the eutectic solder. The temperature sensor  157  is electrically connected to a corresponding pin  12  through a conductive wire. 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the optical sub-module  10  further includes a photodetector  156  disposed on the second functional portion  153 . For example, the photodetector  156  is a monitor photoelectric detector. The photodetector  156  may be attached to the surface of the second functional portion  153  facing the central axis  19  of the base body  11  (i.e., the second conductive layer surface  15122 ) through the conductive silver adhesive or the eutectic solder. The photodetector  156  is electrically connected to a corresponding pin  12  through a conductive wire. 
     In some embodiments of the present disclosure, as shown in  FIG. 10 , the optical sub-module  10  further includes a heater  1541  disposed on the third functional portion  154 . 
     The heater  1541  may be attached to a surface of the third functional portion  154  facing the central axis  19  of the base body  11  (i.e., the second conductive layer surface  15122 ) through, for example, the conductive silver adhesive or the eutectic solder. The heater  1541  is configured to compensate for and supplement any insufficient heating capacity of the temperature regulator  14 . 
     The heater  1541  includes a tantalum nitride (TaN) thin-film resistor, a chip resistor (such as a wire bondable chip resistor), or any other resistor. The heater  1541  is electrically connected to a corresponding pin  12  through a conductive wire. 
     In some embodiments of the present disclosure, the second functional portion  153  is more proximate to the top face  112  than the third functional portion  154 . 
     It will be understood that the third functional portion  154  may not be provided with the heater  1541 . That is, the third functional portion  154  may be an empty bonding pad. 
     It will be understood that, the second functional portion  153  may not be provided with the temperature sensor  157 . 
     It will be understood that, the above manner of dividing the conductive layer into a plurality of functional portions is only an example. In the embodiments of the present disclosure, the conductive layer may be divided into four or more functional portions, and different functional portions are configured to be provided with different functional devices. 
     It will be understood that, in a case where the light emitter  15  is directly disposed on the second heat exchange surface  142  of the temperature regulator  14 , a plurality of functional portions for providing different functional devices may also be formed on (e.g., directly on) the second heat exchange surface  142  of the temperature regulator  14 . 
     In some embodiments of the present disclosure, the metal wires and the conductive wires may be gold wires. 
     In some embodiments of the present disclosure, as shown in  FIGS. 2 and 3 , the optical sub-module  10  further includes a casing cap assembly. The casing cap assembly includes a casing cap body  16 . The casing cap body  16  is disposed on the base body  11 . The heat sink  13 , the temperature regulator  14  and the light emitter  15  are disposed in a chamber enclosed by the casing cap body  16  and the base body  11 . 
     The casing cap assembly further includes a lens  162 , a fixing member  163  for supporting the lens, and an opening  161  disposed on a surface of the casing cap body  16  away from the top face  112 . The lens  162  is disposed at the opening  161  to seal the opening  161 . 
     With continued reference to  FIG. 3 , an orthographic projection of the light emitter  15  on the top face  112  is within a boundary of an orthographic projection of the lens  162  on the top face  112 . Therefore, light emitted by the light emitter  15  may be transmitted to an outside of the optical sub-module  10  through the lens  162 . 
     For example, the light emitted by the light emitter  15  is perpendicular to the surface of the base body  11  (for example, the top face  112  or the bottom face  111 ), and is transmitted to the outside of the optical sub-module  10  after passing through the lens  162  on the casing cap body  16 . That is, a propagation direction of the light emitted by the light emitter  15  is not changed when the light emitted by the light emitter  15  passes through the lens  162 . 
     The fixing member  163  is used for supporting the lens  162  and fixing the lens  162  at the opening  161 . For example, the fixing member is a metal member for supporting the lens  162 . 
     In some embodiments of the present disclosure, a casing for insertion of a socket of an external optical fiber patch cord may be mounted outside the casing cap body  16 , such as on an external surface of the casing cap body  16 , so that the light emitted by the light emitter  15  may be coupled to a core of the external optical fiber patch cord. 
     In some embodiments of the present disclosure, a process of mounting the components of the optical sub-module  10  may be as follows. 
     As shown in  FIG. 6 , in a case where the heat sink  13  and the base body  11  are of an integrated structure, the heat sink  13  and base body  11  may be integrally formed by means of a die or machining, and the groove  131  of the heat sink  13  may extend in a direction perpendicular to (or approximately perpendicular to) the base body  11 . 
     The two insulating plates  17  may be attached to the respective end faces of the side arms  133   a  and  133   b  of the heat sink  13  by means of eutectic soldering or in other similar manners. 
     After the insulating plates  17  are mounted, the temperature regulator  14  is mounted. The temperature regulator  14  is inserted into the groove  131  of the heat sink  13 , such that the first heat exchange surface  141  of the temperature regulator  14  is attached to the inner wall (i.e., the bottom wall  1321  of the groove  131 ) of the groove  131  of the heat sink  13 , the second heat exchange surface  142  of the temperature regulator  14  faces the plurality of pins  12 , and an upper side of the temperature regulator  14  (i.e., a side of the temperature regulator  14  facing away from the top face  112  of the base body  11 ) and the top face of the heat sink body  132  of the heat sink  13  (i.e., a face of the heat sink body  132  facing away from the top face  112 ) are in a same plane (i.e., coplanar). 
     After the temperature regulator  14  is mounted, the substrate  151  is attached to the second heat exchange surface  142  of the temperature regulator  14 , such that the upper side of the substrate  151  (i.e., the substrate side surface  1515 ) and the surface of the heat sink body  132  of the heat sink  13  facing away from the top face  112  are in a same plane (i.e., coplanar), and the second body surface  1514  of the substrate  151  and the surfaces of the insulating plates  17  facing the plurality of pins  12  are in a same plane (i.e., coplanar). 
     After the substrate  151  is mounted, the functional devices such as the light emitter  15 , the photodetector  156  and the temperature sensor  157  are mounted thereon. 
     Here, an accuracy of a mounting position of the light emitter  15  directly affects a coupling efficiency of the external optical fiber patch cord. Therefore, in order to ensure the accuracy of the mounting position of the light emitter  15 , in a process of mounting the light emitter  15 , taking the side arms  133   a  and  133   b  on both sides of the heat sink  13  as reference, a position of the light emitter  15  is adjusted, such that the light-emitting strip  1551  of the light emitter  15  is coincident with the central axis  19  of the base body  11 . That is, a position of the light emitter  15  in an X-axis direction is adjusted. Taking the upper surface of the heat sink  13  as a reference surface, a distance between the light emitter  15  and the top face  112  of the base body  11  is adjusted. That is, a position of the light emitter  15  in a Z-axis direction is adjusted, such that the distance between the light emitter  15  and the top face  112  of the base body  11  satisfies a distance providing adequate optical coupling of the external optical fiber patch cord. 
     In the case where the heat sink  13  and the base body  11  are formed as an integrated structure, since a position of the heat sink  13  relative to the base body  11  has been determined, and a structural design of the groove  131  of the heat sink  13  has been determined, the position of the light emitter  15  in the Y-axis direction is determined. That is, a distance between the light emitter  15  and a plane where the central axis  19  of the base body  11  is in is determined. Therefore, in a process of mounting the light emitter  15  on the substrate  151 , the position of the light emitter  15  may be determined simply just by adjusting the position of the light emitter  15  in the Z-axis direction and the position of the light emitter  15  in the X-axis direction. 
     It will be noted that, the Z-axis direction is a direction perpendicular to the bottom face  111  of the base body  11  and pointing from the bottom face  111  towards the top face  112 . The X-axis direction is a direction pointing from one side arm  133   a  of the heat sink  13  to the other side arm  133   b  of the heat sink  13 . The Y-axis direction is a direction perpendicular to a plane composed of the X-axis and the Z-axis. 
     The above mounting manner not only reduces a difficulty of determining the position of the light emitter  15  and improves production efficiency, but also reduces a production cost and improves a product yield. Compared with a solution in which positions in three directions of the light emitter  15  need to be adjusted in the TO packaging, in the embodiments of the present disclosure, the difficulty of determining the position of the light emitter  15  in a process of manufacturing an optical sub-module may be effectively reduced. 
     Since the heat sink  13  in the embodiments of the present disclosure includes the groove  131 , by directly embedding the temperature regulator  14  into the groove  131  of the heat sink  13 , a position of the temperature regulator  14  relative to the heat sink  13  does not need to be greatly adjusted in the process of manufacturing the optical sub-module, a difficulty of mounting the temperature regulator  14  is reduced, and a positioning accuracy is high and improved. 
     In addition, a light emitter having a high transmission rate, such as a light emitter having a transmission rate of 25 Gbit/s, or even a light emitter having a transmission rate of up to 50 Gbit/s, is suitable for the optical sub-module in the embodiments of the present disclosure. 
     The embodiments of the present disclosure further provide an optical module. As shown in  FIG. 11 , the optical module  20  includes a circuit board  21  and at least one optical sub-module  10 , as described above, disposed on the circuit board  21 . 
     For example, the circuit board  21  is a printed circuit board (PCB). 
     The above descriptions are merely preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Any modification, equivalent replacement, or improvement made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.