Patent Publication Number: US-10761282-B2

Title: Optical-electrical hybrid module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. patent application Ser. No. 15/341,604, filed Nov. 2, 2016, which issued as U.S. Pat. No. 9,995,893 on Jun. 12, 2018, which is a Continuation Application of U.S. application Ser. No. 14/591,197, filed Jan. 7, 2015 and issued as U.S. Pat. No. 9,500,822 on Nov. 22, 2016, which is a Continuation Application of U.S. application Ser. No. 13/926,346, filed Jun. 25, 2013 and issued as U.S. Pat. No. 8,950,950 on Feb. 10, 2015, and which claims priority from Japanese Priority Application JP-2012-177010, filed in the Japan Patent Office on Aug. 9, 2012, the entire contents of which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     The present technology relates to an optical-electrical hybrid module, and more particularly, to an optical-electrical hybrid module intended to realize miniaturization and high density while suppressing loss in a device in which an optical fiber is used. 
     In recent years, in various electronic devices, as an amount of information to be dealt with has been increasing, so has use of an optical fiber as an information transmission channel. 
     In this case, for example, one end of the optical fiber is connected to an information processing device via a light transmission module. This light transmission module converts an electrical signal output from the information processing device into an optical signal and emits the optical signal to the optical fiber. Further, a light reception module is connected to the other end of this optical fiber. This light reception module converts the optical signal propagating through the optical fiber into an electrical signal. 
     Further, the increasing amount of information to be dealt with has necessitated higher speed information communication. 
     For example, it is necessary to install a light transmission module or a light reception module as a high-density array for miniaturization in order to achieve high-speed information communication in a super computer, a data center, or the like. 
     Further, the number of parts tends to increase due to the high-density array, and an amount of heat generated during operation of an electronic device increases correspondingly. Therefore, it is important to obtain sufficient shield effects and take sufficient heat radiation measures. 
     Technology intended to sufficiently obtain both a shield effect and a cooling effect in a shield structure for a chip part has been proposed (e.g., see Japanese Patent Laid-Open No. 2004-71658). 
     SUMMARY 
     However, when a light transmission module or a light reception module is mounted at high density, it is necessary to extend an optical fiber in a desired direction while avoiding adjacent modules. Therefore, when the light transmission module or the light reception module is mounted at high density, it is necessary to sharply bend the optical fiber, and a loss in the optical fiber occurs at sharp bends. 
     When a bend radius of the optical fiber increases and the optical fiber is gently bent, the loss does not occur. However, since a distance between the modules increases by doing so, it is difficult for the modules to be a high-density array and it is detrimental to miniaturization. 
     The present technology has been made in view of such circumstances and is intended to realize miniaturization and high density while suppressing loss in a device in which an optical fiber is used. 
     According to an embodiment of the present disclosure, there is provided an optical-electrical hybrid module including a substrate on which a plurality of optical communication modules are arranged, the plurality of optical communication modules transmitting or receiving an optical signal through an optical fiber cable and performing conversion between the optical signal and an electrical signal. A shield case covering the optical communication modules includes a surface inclined in a direction away from a position in which the optical fiber cable is mounted to each optical communication module. 
     A top surface of the shield case may include a horizontal surface having a first height determined according to a thickness of a part having a greatest thickness among parts mounted on wiring substrates of the optical communication modules, and a horizontal surface having a second height determined according to a thickness of a part having a smallest thickness among the parts mounted on the wiring substrates of the optical communication modules. 
     In the top surface of the shield case, the horizontal surface having the second height may extend by 2 mm to 15 mm long in a direction in which the optical fiber cable extends. 
     A difference between the first height and the second height may be 0.2 mm or more. 
     A part having a greatest thickness among parts mounted on the wiring substrates of the optical communication modules may be a silicon interposer. 
     The shield case may be formed of a metal material. 
     In one aspect of the present technology, an optical signal is transmitted or received through an optical fiber cable, a plurality of optical communication modules that perform conversion between the optical signal and an electrical signal are arranged, and a shield case covering the optical communication modules includes a surface inclined in a direction away from a position in which the optical fiber cable is mounted to the optical communication module. 
     According to embodiments of the present technology, it is possible to realize miniaturization and high density while suppressing loss in an apparatus in which an optical fiber is used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an example configuration of an optical-electrical hybrid module in which optical communication modules of the related art are installed as a high-density array; 
         FIG. 2  is a graph illustrating a relationship between a bend radius and optical loss of an optical fiber; 
         FIG. 3  is a diagram illustrating an example of the optical communication modules shown in  FIG. 1  installed on a substrate in consideration of a bend radius; 
         FIG. 4  is a diagram illustrating an example configuration of an optical communication module according to an embodiment of the present technology. 
         FIG. 5  illustrates an example configuration of an optical-electrical hybrid module in which optical communication modules according to the embodiment of the present technology are installed as a high-density array; and 
         FIG. 6  is a diagram illustrating an example configuration of an optical communication module according to another embodiment of the present technology. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the appended drawings. Note that, in this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these structural elements is omitted. 
     In recent years, in various electronic devices, use of an optical fiber as an information transmission channel has been increasing along with the amount of information to be dealt with. 
     In this case, for example, one end of the optical fiber is connected to an information processing device via a light transmission module. This light transmission module converts an electrical signal output from the information processing device into an optical signal and emits the optical signal to the optical fiber. Further, a light reception module is connected to the other end of this optical fiber. This light reception module converts the optical signal propagating through the optical cable into an electrical signal. 
     The light transmission module and the light reception module are collectively referred to as an optical communication module. Usually, a plurality of optical communication modules are arranged on a substrate in which electrical wiring patterns or the like are provided in advance, configured as an optical-electrical hybrid module, and are incorporated into various computers or the like. 
     Further, a surface of the optical communication module is covered by a shield case to protect the optical communication module from heat generated during operation of a device such as a computer. 
     Further, the increasing amount of information to be dealt with has necessitated higher speed information communication. 
     For example, it is necessary to install optical communication modules as a high-density array and miniaturize an optical-electrical hybrid module in order to achieve high-speed information communication in a super computer, a data center or the like. 
     However, when the optical communication modules are installed at high density, it is necessary to extend an optical fiber in a desired direction while avoiding the adjacent modules. Therefore, when the optical communication modules are mounted at high density, it is necessary to sharply bend the optical fiber, and optical loss occurs at sharp bends. 
       FIG. 1  illustrates an example configuration of an optical-electrical hybrid module  1  in which optical communication modules of the related art are installed as a high-density array. In the example of  FIG. 1 , an optical communication module  20 - 1  to an optical communication module  20 - 3  are installed on a substrate  10 . 
     In  FIG. 1 , a distance between the adjacent optical communication modules is d. In other words, the optical communication module  20 - 1  and the optical communication module  20 - 2  are installed the distance d apart, and the optical communication module  20 - 2  and the optical communication module  20 - 3  are also installed the distance d apart. 
     Further, the optical communication module  20 - 1  is configured in such a manner that a printed circuit substrate  22 - 1 , a silicon interposer  23 - 1  and the like are covered with a shield case  21 - 1 . The optical communication module  20 - 2  and the optical communication module  20 - 3  are also configured like the optical communication module  20 - 1 . 
     Further,  FIG. 1  is drawn to show the inside of the shield case  21 - 1  for convenience. For example, the sides or the like of the shield case  21 - 1  are not drawn. 
     An optical fiber cable  31 - 1  to an optical fiber cable  31 - 3  connected to the optical communication module  20 - 1  to the optical communication module  20 - 3 , respectively, extend toward a connector  40  arranged on the left side of  FIG. 1 . 
     For example, the optical fiber cable  31 - 1  extends to the left in  FIG. 1  while avoiding the optical communication module  20 - 2  and the optical communication module  20 - 3 . Therefore, the optical fiber cable  31 - 1  is sharply bent upward at a position indicated by an arrow  51 - 1  and to the left at a position indicated by an arrow  51 - 2  in  FIG. 1 . 
     Further, for example, the optical fiber cable  31 - 2  extends to the left in  FIG. 1  while avoiding the optical communication module  20 - 3 . Therefore, the optical fiber cable  31 - 2  is sharply bent upward at a position indicated by an arrow  52 - 1  and to the left at a position indicated by an arrow  52 - 2  in  FIG. 1 . 
     When the optical fiber cable is sharply bent in this way, optical loss occurs at the sharp bends. 
       FIG. 2  is a graph illustrating a relationship between a bend radius and optical loss in the optical fiber. In  FIG. 2 , a horizontal axis indicates the bend radius of the optical fiber, and a vertical axis indicates optical loss. The relationship between the bend radius and the optical loss is shown by a line  61 . 
     Further, here, the relationship between the bend radius and the optical loss in the optical fiber at a wavelength λ=850 nm of light incident on the optical fiber is shown. 
     The line  61  sharply rises from a position in which the bend radius is 20 mm or less, as shown in  FIG. 2 . In other words, it is desirable to design the optical-electrical hybrid module so that the bend radius of the optical fiber cable is equal to or more than 20 mm in order to suppress the optical loss in the optical fiber. 
     However, the optical communication module is usually configured as an extremely small part having a size of 1 cm or less. 
       FIG. 3  is a diagram illustrating an example in which the optical communication module  20 - 1  to the optical communication module  20 - 3  shown in  FIG. 1  are installed on the substrate  10  so that the bend radius of the optical fiber cable is 20 mm or more. 
     In the case of  FIG. 3 , there is no portion in which the optical fiber cable  31 - 1  and the optical fiber cable  31 - 2  are sharply bent, unlike the case of  FIG. 1 . However, in the case of  FIG. 3 , the distance between the adjacent optical communication modules is greater than that in the case of  FIG. 1 . 
     In other words, in the case of  FIG. 3 , the distance between the adjacent optical communication modules is d′, which is greater than d. In other words, the optical communication module  20 - 1  and the optical communication module  20 - 2  are installed the distance d′ apart, and the optical communication module  20 - 2  and the optical communication module  20 - 3  are installed the distance d′ apart. 
     When the adjacent optical communication modules are arranged a large distance apart as in  FIG. 3 , the optical loss in the optical fiber can be suppressed, but it is difficult to install, at high density, the optical communication modules configured as extremely small parts. In other words, in the related art, it is difficult to install the optical communication modules at high density while suppressing the optical loss in the optical fiber. 
     Therefore, the present technology is intended to install the optical communication modules at high density while suppressing the optical loss in the optical fiber. 
       FIG. 4  is a diagram illustrating an example configuration of an optical communication module according to an embodiment of the present technology. 
     A printed wiring substrate  122  is provided in an optical communication module  120  shown in  FIG. 4 . The printed wiring substrate  122  is a substrate in which electrical wiring patterns or the like have been printed in advance, and various parts are mounted on and beneath the printed wiring substrate  122  in  FIG. 4 . A silicon interposer  123 , a LDD/TIA  125 , and a chip part  126  are mounted on the printed wiring substrate  122 . Further, a VCSEL/PD  124  is attached to the silicon interposer  123 . 
     The VCSEL (Vertical Cavity Surface Emitting LASER)/PD  124  is an optical element that irradiates an optical fiber cable  131  with a laser beam and converts an incident laser beam into an electrical signal. The LDD (Laser Diode Driver)/TIA (Trans Impedance Amplifier)  125  functions as a driver that drives the VCSEL/PD  124  or an IC for amplifying a weak signal. 
     Further, in the optical communication module  120  shown in  FIG. 4 , a shield case  121  is provided to cover various parts mounted on the printed wiring substrate  122 . It is preferable for the shield case  121  to be formed of a metal. Further,  FIG. 4  is drawn to show the inside of the shield case  121  for convenience. For example, the sides or the like of the shield case  121  are not drawn. A socket  128  is provided in a left end in  FIG. 4  of the shield case  121 , and the optical fiber cable  131  extends at the left side in  FIG. 4  via the socket  128 . 
     In the example of  FIG. 4 , an area configured as a horizontal surface at a height h 1  from the printed wiring substrate  122 , an area configured as a horizontal surface at a height h 2  from the printed wiring substrate  122 , and an area inclined from the height h 1  to the height h 2  are included in a top surface of the shield case  121  (an upper surface in  FIG. 4 ). 
     In other words, the top surface of the shield case  121  is configured as the horizontal surface at the height h 1  from the printed wiring substrate  122  in an area  121   a  corresponding to a length w 3  in a horizontal direction in  FIG. 4  from the socket  128 . Further, the top surface of the shield case  121  is configured as a surface inclined from the height h 1  to the height h 2  in an area  121   b  corresponding to a length w 2  on the right side in  FIG. 4  of the above-described area  121   a . Furthermore, the top surface of the shield case  121  is configured as a horizontal surface at the height h 2  from the printed wiring substrate  122  in an area  121   c  corresponding to a length w 1  on the right side in  FIG. 4  of the above-described area  121   b.    
     Here, the height h 1  is a height determined to correspond to a thickness of the silicon interposer  123 , which is a part having a greatest thickness in a vertical direction in  FIG. 4  on the printed wiring substrate  122 . The height h 1  is usually approximately 0.8 mm to 0.2 mm. 
     Further, the height h 2  is a height determined to correspond to a thickness of the chip part  126 , which is a part having a smallest thickness in the vertical direction in  FIG. 4  on the printed wiring substrate  122 . The height h 2  is usually approximately 0.2 mm to 0.6 mm. 
     Further, the height h 3  from the printed wiring substrate  122  to the optical fiber cable  131  is a height determined to correspond to an arrangement position or a shape of the socket  128 . 
     The top surface of the shield case of the optical communication module of the related art is configured as a horizontal surface at the height h 1  from the printed wiring substrate  122  over the entire printed wiring substrate  122 . In other words, the top surface of the shield case of the related art is configured as a horizontal surface at a uniform height corresponding to a height of the part having a greatest thickness in the vertical direction in  FIG. 4  on the printed wiring substrate  122 . 
     In contrast, the top surface of the shield case of the optical communication module according to the embodiment of the present technology has the surface inclined from the height (e.g., the height h 1 ) corresponding to the height of the part having the greatest vertical thickness in  FIG. 4  to a lower height (e.g., the height h 2 ) on the printed wiring substrate  122 . 
     Here, a distance between the adjacent optical communication modules is d and a bend radius of the optical fiber cable is r. Using the height h 1 , the height h 3  and the bend radius r, the distance d can be derived using Equation (1).
 
 d =( r   2 −( r −( h 1− h 3)) 2 ) 1/2   (1)
 
     For example, if (h 1 −h 3 )=1 mm, the distance d is 6.2 mm from Equation (1) when the horizontal top surface at the height h 1  from the printed wiring substrate  122  over the entire printed wiring substrate  122  is provided, as in the shield case of the optical communication module of the related art. In other words, in a scheme of the related art, it was necessary to perform an arrangement with a distance between adjacent optical communication modules being equal to or more than 6.2 mm. 
     In contrast, when the optical communication module according to the embodiment of the present technology is used as shown in  FIG. 4 , if (w 1 +w 2 ) is 6.2 mm or more, the distance d can be approximately 0. When an optical communication module having a general size is configured, it is desirable for w 1  to be 2 to 15 mm and (h 1 −h 2 ) to be 0.2 mm or more. 
       FIG. 5  illustrates an example configuration of an optical-electrical hybrid module to which the present technology has been applied, which is an optical-electrical hybrid module  100  in which optical communication modules according to the embodiment of the present technology are installed as a high-density array. In the example of the  FIG. 5 , an optical communication module  120 - 1  to an optical communication module  120 - 3  according to the embodiment of the present technology are installed on a substrate  110 . 
     An optical fiber cable  131 - 1  to an optical fiber cable  131 - 3 , connected to the optical communication module  120 - 1  to the optical communication module  120 - 3 , respectively, extend toward a connector  140  arranged on the left side in  FIG. 5 . 
     For example, the optical fiber cable  131 - 1  extends to the left in  FIG. 5  while avoiding the optical communication module  120 - 2  and the optical communication module  120 - 3 . However, in the example of  FIG. 5 , there is no portion where the optical fiber cable  131 - 1  is sharply bent, unlike the case described above with reference to  FIG. 1 . Further, the optical fiber cable  131 - 2  extends to the left in FIG.  5  while avoiding the optical communication module  120 - 2  and the optical communication module  120 - 3 . However, in the example of  FIG. 5 , there is no portion where the optical fiber cable  132 - 1  is sharply bent, unlike the case described above with reference to  FIG. 1 . 
     Therefore, according to the embodiment of the present technology, it is possible to suppress optical loss in the optical fiber. 
     Further, in  FIG. 5 , a distance between the adjacent optical communication modules is d. In other words, the optical communication module  120 - 1  and the optical communication module  120 - 2  are installed the distance d apart, and the optical communication module  120 - 2  and the optical communication module  120 - 3  are also installed the distance d apart. In other words, it is unnecessary for the distance between the adjacent optical communication modules to be d′, which is greater than d, unlike the case of  FIG. 3 . 
     Therefore, according to the embodiment of the present technology, it is possible to install the optical communication modules at high density. 
       FIG. 6  is a diagram illustrating another configuration example of an optical communication module according to an embodiment of the present technology. 
     In an optical communication module  120  shown in  FIG. 6 , a printed wiring substrate  122  is provided, as in the case of  FIG. 4 . Further, as in the case of  FIG. 4 , a silicon interposer  123 , an LDD/TIA  125 , and a chip part  126  are mounted on the printed wiring substrate  122 . Further, a VCSEL/PD  124  is attached to the silicon interposer  123 . 
     The optical communication module  120  shown in  FIG. 6  differs from that of  FIG. 4  in a configuration of the shield case  121 . Further,  FIG. 6  is drawn to show the inside of the shield case  121  for convenience. For example, the sides or the like of the shield case  121  are not drawn. 
     In the example of  FIG. 6 , an area configured as a horizontal surface at a height h 1  from the printed wiring substrate  122 , and an area inclined from the height h 1  to a surface of the printed wiring substrate  122 , are included in a top surface of the shield case  121  (a top surface in  FIG. 6 ). 
     In other words, the top surface of the shield case  121  is configured as a horizontal surface at the height h 1  from the printed wiring substrate  122  in an area  121   d  corresponding to a length w 5  in a horizontal direction in  FIG. 6  from a socket  128 . Further, the top surface of the shield case  121  is configured as a surface inclined from the height h 1  to the surface of the printed wiring substrate  122  in an area  121   e  corresponding to a length w 4  on the right side in  FIG. 6  of the above-described area  121   d.    
     In the case of  FIG. 6 , for example, the horizontal surface corresponding to the area  121   c  in the configuration of  FIG. 4  is not included. 
     If the optical communication module  120  having the configuration shown in  FIG. 6  is used, it is not necessary to sharply bend the optical fiber cable  131  even when the distance between the optical communication modules  120  is small. Therefore, even when the configuration of  FIG. 6  is applied, according to the embodiment of the present technology, optical loss in the optical fiber can be suppressed and the optical communication modules can be installed at high density. 
     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof. 
     Additionally, the present technology may also be configured as below.
     (1) An optical-electrical hybrid module including:
       a substrate on which a plurality of optical communication modules are arranged, the plurality of optical communication modules transmitting or receiving an optical signal through an optical fiber cable and performing conversion between the optical signal and an electrical signal,   wherein a shield case covering the optical communication modules includes a surface inclined in a direction away from a position in which the optical fiber cable is mounted to each optical communication module.   
       (2) The optical-electrical hybrid module according to (1), wherein a top surface of the shield case includes a horizontal surface having a first height determined according to a thickness of a part having a greatest thickness among parts mounted on wiring substrates of the optical communication modules, and a horizontal surface having a second height determined according to a thickness of a part having a smallest thickness among the parts mounted on the wiring substrates of the optical communication modules.   (3) The optical-electrical hybrid module according to (2), wherein, in the top surface of the shield case, the horizontal surface having the second height extends by 2 mm to 15 mm long in a direction in which the optical fiber cable extends.   (4) The optical-electrical hybrid module according to (2), wherein a difference between the first height and the second height is 0.2 mm or more.   (5) The optical-electrical hybrid module according to (2), wherein the part having the greatest thickness among the parts mounted on the wiring substrates of the optical communication modules is a silicon interposer.   (6) The optical-electrical hybrid module according to any one of (1) to (5), wherein the shield case is formed of a metal material.   

     The present disclosure contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2012-177010 filed in the Japan Patent Office on Aug. 9, 2012, the entire content of which is hereby incorporated by reference.