Patent Publication Number: US-2021165173-A1

Title: Energy-efficient optical communication module and method of manufacturing thereof

Description:
FIELD 
     The subject matter herein generally relates to optical communication modules having optical-signal transmitters directly connecting to optical fibers, and a method of manufacturing thereof. 
     BACKGROUND 
     An optical communication network has the characteristics of low transmission loss, high data confidentiality, total immunity to electromagnetic interference (EMI), and wide bandwidth, and is a main communication method today. The optical communication module is an important basic component in optical communication technology. The optical communication module is used to receive optical signals from optical network and convert the optical signals into electrical signals. The optical communication module can also convert electrical signals into optical signals, and then transmit the optical signals outward through the optical network. 
     The conventional optical communication module utilizes a vertical-cavity surface-emitting laser (VCSEL) to emit light beams as optical signals. In order for the light beam emitted by the VCSEL to enter into the optical fiber, in the conventional technology, a lens is used to focus the light beam, and then the light beam is reflected by a light-guide element to the optical fiber. Therefore, the conventional optical communication module uses more optical devices such as lenses and light-guide elements, thereby increasing the manufacturing cost of the optical communication module. In addition, the light beam passing through the lens and the light-guide element is inefficient because of energy losses, and this in turn affects the performance of the optical communication module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present disclosure are better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. 
         FIG. 1  is a schematic view of an optical communication module in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is a perspective view of the optical communication module of  FIG. 1 , some components being omitted. 
         FIG. 3  is a flowchart of a method for manufacturing the optical communication module in accordance with embodiments of the present disclosure. 
         FIGS. 4A, 4B, and 4C  show intermediate stages of manufacturing the optical communication module. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures, and components have not been described in detail so as not to obscure the related relevant feature being described. Also, the description is not to be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. 
     The disclosure is illustrated by way of embodiments and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean “at least one.” 
     The term “connected” is directly or indirectly through intervening components, and is not necessarily limited to physical connections. The connection can be such that the objects are permanently connected or releasably connected. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. 
       FIG. 1  is a schematic view of an optical communication module  1  in accordance with a first embodiment of the present disclosure. The optical communication module  1  is configured to be mounted in an electronic device, so that the electronic device can receive and/or transmit optical signals. The electronic device may be a computer, a server, or a router, but it is not limited thereto. The optical communication module  1  may be an optical receiving module, an optical transmitting module, or an optical transceiver module. The optical receiving module may receive optical signals, and convert the optical signals to electrical signals. The optical transmitting module may receive electrical signals from the electronic device and convert the electrical signals to optical signals, and the optical signals can be transmitted out via an optical fiber. In addition, the optical transceiver module can integrate the functions of the optical receiving module and the optical transmitting module, and can be used to receive and transmit optical signals. 
     In this embodiment, the optical communication module  1  is an optical transmitting module, but not limited thereto. The optical communication module  1  includes a housing  10 , a printed circuit board  20 , chips  30 , an optical-signal transmitter  40 , an optical fiber  50 , and an optical-fiber connector  60 . When the optical communication module  1  is an optical receiving module, the optical-signal transmitter  40  is replaced by an optical-signal receiver. The housing  10  may be an elongated structure, extending along an extension direction D 1 . The housing  10  may be a metal housing configured to shield against electromagnetic waves of the electronic device entering the housing  10 , so as to provide electromagnetic protection for components such as the chips  30  and the optical-signal transmitter  40  in the housing  10 . In some embodiments, the interior of the housing  10  forms a sealed space, so as to prevent moisture and dust outside the housing  10  from entering the housing  10 , and improve the service life and the signal reliability of the optical communication module  1 . 
     The printed circuit board  20  is disposed in the housing  10 , and one end of the printed circuit board  20  passes through a side wall  11  of the housing  10 . In other words, the end of the printed circuit board  20  is exposed out of the housing  10 . The printed circuit board  20  may be an elongated structure extending along the extension direction D 1 . The printed circuit board  20  may be a rigid printed circuit board (Rigid PCB or RPC). In this embodiment, the printed circuit board  20  includes an insulated substrate  21 , a circuit layer (first circuit layer)  22 , a circuit layer (second circuit layer)  23 , and a connection layer  24 . The insulated substrate  21  may be made of rigid materials. The circuit layer  22  is disposed on a top surface  211  of the insulated substrate  21 , and made of conductive materials. The circuit layer  23  is disposed on a bottom surface  212  of the insulated substrate  21 , and made of conductive materials. 
     The connection layer  24  may be disposed on the top surface  211  and/or the bottom surface  212  of the insulated substrate  21 . In other words, the connection layer  24  is electrically connected to the circuit layer  22  and/or the circuit layer  23 . The connection layer  24  can be exposed out of the housing  10 . In this embodiment, one end of the printed circuit board  20  can be inserted into the connector of the electronic device (not shown). The connection layer  24  can be in contact with the connector, and thus the printed circuit board  20  can receive electrical signals from the electronic device via the connection layer  24 . In some embodiments, the connection layer  24  may be disposed other than on the top surface  211  of the insulated substrate  21 . In some embodiments, the connection layer  24  may be disposed other than on the bottom surface  212  of the insulated substrate  21 . 
     The chips  30  are in the housing  10 , and mounted on the printed circuit board  20 . In this embodiment, the chips  30  are mounted on the printed circuit board  20  by chip-on-board (COB) package. In some embodiments, the chips  30  are mounted on the printed circuit board  20  by surface-mount technology (SMT). The chips  30  can be adhered to the top surface  211  and/or the bottom surface  212  of the insulated substrate  21 , and the chips  30  can be electrically connected to the circuit layer  22  and/or the circuit layer  23  by wires (not shown). In some embodiments, the printed circuit board  20  does not include the circuit layer  23 , the chips  30  are mounted other than on the bottom surface  212  of the insulated substrate  21 . 
     In this embodiment, all the chips  30  include a control chip  31  and a monitor photodiode (MPD) chip  32 , but not limited thereto. The control chip  31  is electrically connected to the monitor photodiode chip  32  and the optical-signal transmitter  40 . The control chip  31  is used to drive the optical-signal transmitter  40 . In this embodiment, the control chip  31  can drive the optical-signal transmitter  40  according to the electrical signals from the electronic device to generate light beams, so as to make optical signals in the light beams. The monitor photodiode chip  32  is used to detect conditions and states, such as power levels, of the light beams generated by the optical-signal transmitter  40 . 
       FIG. 2  is a perspective view of the optical communication module  1  of  FIG. 1 . For the purpose of clarity, some components are omitted in  FIG. 2 . The optical-signal transmitter  40  is in the housing  10 . The optical-signal transmitter  40  can be mounted on the printed circuit board  20 , and is electrically connected to the circuit layer  22  (and the monitor photodiode chip  32 ) via a wire W 1 . The optical-signal transmitter  40  is electrically connected to the control chip  31  and the monitor photodiode chip  32 . The control chip  31  controls the optical-signal transmitter  40  to emit the light beams according to the electrical signals. 
     The optical-signal transmitter  40  includes a base  41 , a light emitting element  42 , and an electrode  43 . In this embodiment, the base  41  of the optical-signal transmitter  40  is affixed to the top surface  211  of the insulated substrate  21  via a glue G 1 . In some embodiments, the glue G 1  includes epoxy, but is not limited thereto. 
     The light emitting element  42  is disposed in the base  41 . The light emitting element  42  may be a vertical-cavity surface-emitting Laser (VCSEL), used to emit laser. In some embodiments, the light emitting element  42  is a light emitting diode (LED). As shown in  FIG. 1  and  FIG. 2 , the electrode  43  is disposed on the base  41 , and electrically connected to the light emitting element  42 . In this embodiment, the wire W 1  is connected to the electrode  43 , and thus the light emitting element  42  is electrically connected to the circuit layer  22 . 
     The optical fiber  50  is connected to the light emitting element  42  and the optical-fiber connector  60 . In this embodiment, one end of the optical fiber  50  is directly connected to the light emitting element  42 . The light emitting element  42  emits the light beam into the optical fiber  50 . In some embodiments, one end of the optical fiber  50  is welded to the light emitting element  42 , and thus the light beam emitted by the optical-signal transmitter  40  can directly enter into the optical fiber  50 . Therefore, energy losses of light beam can be reduced, and the performance of optical communication module  1  is improved. Moreover, the number of optical devices of the optical communication module  1 , such as lenses and light guide elements, is reduced, thereby reducing the manufacturing cost of the optical communication module  1 . 
     The optical-fiber connector  60  is affixed to a side wall  12  of the housing  10 . In this embodiment, the side wall  12  is opposite to the side wall  11 . The optical-fiber connector  60  and the connection layer  24  are at opposite sides of the housing  10 . One end of the optical fiber  50  is affixed in the optical-fiber connector  60 . 
       FIG. 3  is a flowchart of a method for manufacturing the optical communication module  1  in accordance with embodiments of the present disclosure.  FIG. 4A  to  FIG. 4C  show intermediate stages of manufacturing the optical communication module  1 . In  FIG. 4A  to  FIG. 4C , the optical communication module  1  is an example of an optical transmitting module. However, the method of manufacturing the optical communication module  1  can also be applied to an optical receiving module and an optical transceiver module. 
     In step S 101 , as shown in  FIG. 4A , the chips  30  are mounted on the printed circuit board  20 . The chips  30  can be mounted on the printed circuit board  20  by COB package or SMT. 
     In step S 103 , as shown in  FIG. 4B , the optical-signal transmitter  40  is mounted on the printed circuit board  20 . The optical-signal transmitter  40  can be mounted on the printed circuit board  20  by COB package. The base  41  of the optical-signal transmitter  40  is affixed to the top surface  211  of the insulated substrate  21  by the glue G 1 . Moreover, the optical-signal transmitter  40  is electrically connected to the circuit layer  22  via the wire W 1 . Therefore, the optical-signal transmitter  40  is electrically connected to the control chip  31  and the monitor photodiode chip  32  via the wire W 1 . 
     In step S 105 , as shown in  FIG. 4C , the optical fiber  50  is directly connected to the light emitting element  42  of the optical-signal transmitter  40 . In this embodiment, the light emitting element  42  includes a protection layer  422  connected to an exit surface  421 . Moreover, the protection layer  422  is located in an opening of the base  41 . The light beam generated by the light emitting element  42  is emitted outside the base  41  via the protection layer  422  and the exit surface  421 . 
     In this embodiment, the protection layer  422  and the optical fiber  50  are of the same material, such as glass. The area of the exit surface  421  of the light emitting element  42  is equal to or greater than the area of an incident surface  51  of the optical fiber  50 . Therefore, the optical fiber  50  is saturated by the light beam emitted by the light emitting element  42 . 
     In this embodiment, one end of the optical fiber  50  is welded to the exit surface  421  of the light emitting element  42 . In some embodiments, the incident surface  51  of the optical fiber  50  is attached to the exit surface  421  of the light emitting element  42 . Afterwards, a laser-welding tool emits a high-temperature laser to melt together the incident surface  51  of the optical fiber  50  and the exit surface  421  of the light emitting element  42 . Since the protection layer  422  and the optical fiber  50  are of the same material, the optical fiber  50  is totally combined with the light emitting element  42  after the optical fiber  50  and the light emitting element  42  are cooled. The light beam emitted by the optical-signal transmitter  40  can directly enter the optical fiber  50  and reduce energy losses of the light beam. Moreover, there is no need to provide lenses, light guide elements, and/or reflective elements in the light path of the light beam from the light emitting element  42  to the optical fiber  50 , thereby reducing the manufacturing cost of optical communication module  1 . 
     In the present disclosure, glass-welding one end of the optical fiber  50  to the light emitting element  42  may have various embodiments. For example, a filler such as glass is placed between the exit surface  421  of the light emitting element  42  and the incident surface  51  of the optical fiber  50 . Next, the laser-welding tool emits a high-temperature laser to melt the incident surface  51  of the optical fiber  50  and the exit surface  421  of the light emitting element  42  with the filler. In other words, the filler forms part of the optical fiber  50  and part of the light emitting element  42 . 
     In step S 107 , as shown in  FIG. 1 , the printed circuit board  20  is disposed in the housing  10 , and one end of the printed circuit board  20  passes through the side wall  11  of the housing  10 . Afterwards, the optical-fiber connector  60  is connected to the optical fiber  50 , and affixed to the side wall  12  of the housing  10 , and then the assembly of the optical communication module  1  is finished. 
     By the optical fiber  50  directly connecting the optical-signal transmitter  40 , the light beam emitted by the optical-signal transmitter  40  can directly enter into the optical fiber  50  to reduce the energy loss of the light beam, thereby improving the performance of the optical communication module  1 . Moreover, the optical communication module  1  eliminates the need for optical devices such as lenses and light guide elements, thereby reducing the manufacturing cost of the optical communication module  1 . 
     Many details of the optical communication module are often found in the art, and thus many such details are neither shown nor described. Even though numerous characteristics and advantages of the present technology have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the disclosure is illustrative only, and changes may be made in the detail, especially in matters of shape, size, and arrangement of the parts within the principles of the present disclosure, up to and including the full extent established by the broad general meaning of the terms used in the claims. It will therefore be appreciated that the embodiments described above may be modified within the scope of the claims.