Abstract:
An optical module includes: a circuit board having a surface in which an electronic element is mounted; an optical waveguide array in which a plurality of optical waveguides are formed; an optical element in which an optical signal that is transmitted and received from and to the optical waveguide is input and that is mounted at a side surface of the circuit board; and a connection member that connects the optical element and the electronic element, wherein a connection portion of a side surface of the circuit board in which the connection member is received has a curved shape.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0007148 filed in the Korean Intellectual Property Office on Jan. 15, 2015, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to an optical module. More particularly, the present invention relates to an optical module that transfers an electric signal that is generated according to an applied optical signal to a circuit board. 
     (b) Description of the Related Art 
     In general, in a low speed system, a connection between circuit boards and between chips or between systems is performed through a metal electrical cable. However, as in a next generation information communication system that is formed with a large capacity parallel computer or an ATM switching system having a capacity of 1 Tb/s or more, as a large amount of information is transmitted and transmission speed is improved, when using such a metal cable, an electrical problem such as skew and electromagnetic interference (EMI) occurs and thus operation efficiency of the system is deteriorated and it is difficult to integrate a system. 
     Therefore, technology that performs an optical connection using an optical transmitting/receiving module has been developed, and a method of directly coupling an optical receiving element to a ribbon optical fiber multichannel optical connector having a reflector that is located with a tilt angle of 45° with an optical coupling method within the optical transmitting/receiving module, a method of coupling an optical transmitting/receiving element to a polymer optical waveguide having a reflector that is located with a tilt angle of 45° and connecting the polymer optical waveguide to a multichannel optical connector, a method of vertically coupling an optical transmitting/receiving element to a polymer optical waveguide and connecting the polymer optical waveguide to a multichannel optical connector, and a method of vertically coupling an optical transmitting/receiving element that is fixed to a plastic package to a multichannel optical connector are used. In this case, as an optical transmitting element, i.e., an optical source, a Vertical Cavity Surface Emitting Laser (VCSEL) array is used, and as optical receiving element, i.e., an optical detector, a photodiode (PD) array is used. 
     A conventional optical module reflects light that is oscillated through a light emitting port by 90° by an optical waveguide and transfers the light to an optical fiber that is connected to an optical connector along a core that is formed in a board. “ParaBIT-1: 60-Gb/s-Throughput Parallel Optical Interconnect Module, presenter: N. Usui” that was published in ECTC 2000 in May of 2000 has a structure in which a 24 channel polymer waveguide film in which a plane reflector is located with a tilt angle of 45° and a 24-optical fiber BF connector are connected, and the waveguide film and the connector are manually assembled. 
     In this technology, because a method of coupling an optical transmitting/receiving element to a polymer optical waveguide having a reflector that is located with a tilt angle of 45° and connecting a polymer optical waveguide to a multichannel optical connector may relatively easily form a reflector and house an optical coupler, an optical switch, and a Wavelength Division Multiplexing (WDM) element in a polymer optical waveguide, the method can extend a function of an entire module and is thus evaluated as a very effective method. 
     However, in order to produce an optical transmitting/receiving module for parallel optical connection having an extending function, when using the optical coupling technology, even if a small misalignment occurs in coupling of the optical transmitting/receiving element and an optical fiber, a large optical coupling loss occurs and thus satisfactory efficiency is not obtained. Therefore, structure enhancement of an optical transmitting/receiving module for parallel optical connection that can minimize a coupling loss is urgently requested. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide an optical module having advantages of being capable of preventing a loss such as optical coupling efficiency reduction and a loss of bandwidth occurring due to rapid direction conversion of an electric signal line when transmitting a high speed signal. 
     An exemplary embodiment of the present invention provides an optical module including: a circuit board having a surface in which an electronic element is mounted; an optical waveguide array in which a plurality of optical waveguides are formed; an optical element in which an optical signal that is transmitted and received from and to the optical waveguide is input and that is mounted at a side surface of the circuit board; and a connection member that connects the optical element and the electronic element, wherein a connection portion of a side surface of the circuit board in which the connection member is received has a curved shape. 
     The connection member may be curvedly formed along a curved shape of a connection portion of a side surface of the circuit board. 
     A connection portion of a curved shape of a side surface of the circuit board may be formed with a rod that is made of glass. 
     The glass rod may have a cross-sectional shape of a quarter of a circle. 
     The optical element may be formed in a direction opposite to that of the electronic element in the circuit board, and the glass rod may be installed at a side surface of the circuit board. 
     The connection member may include a transmission line, and a wire bonding unit that connects the electronic element and the optical element at both ends of the transmission line. 
     The transmission line may be formed in a pattern in the glass rod. 
     An optical module according to an exemplary embodiment of the present invention can simplify a production process by forming a transmission line in a glass rod. 
     Further, by minimizing a loss of an electric signal by forming a curved surface using a glass rod, a bandwidth can be extended and various angles of transmission line can be implemented. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating an optical module according to a first exemplary embodiment of the present invention. 
         FIG. 2  is a cross-sectional view illustrating a portion of an optical module according to a first exemplary embodiment of the present invention. 
         FIG. 3  is a cross-sectional view illustrating a portion of an optical module according to a second exemplary embodiment of the present invention. 
         FIG. 4  is a cross-sectional view illustrating a portion of an optical module according to a third exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
     Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
     Further, in the drawings, a size and thickness of each element are randomly represented for better understanding and ease of description, and the present invention is not limited thereto. 
     In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
       FIG. 1  is a perspective view illustrating an optical module according to a first exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , a circuit board  10  in which a plurality of electronic elements  40  and an optical element  30  are mounted and an optical waveguide array  20  in which a plurality of optical waveguides  22  are connected are coupled to form an optical module  100 . The plurality of optical waveguides  22  are arranged parallel to the optical element  30  and an optical signal is input thereto, and a signal that is generated in the optical element  30  is transferred to the electronic element  40  through a connection member  50 . 
     The optical waveguide array  20  is installed at a side surface of the circuit board  10 , and a guide unit may be formed to not separate from a predetermined location. 
     In the optical waveguide array  20 , a plurality of optical elements  30  are mounted at a side surface of the circuit board  10  to correspond to the plurality of optical waveguides  22 . 
     The electronic element  40  is mounted at an upper surface of the circuit board  10 , and is connected to the optical element  30  that is mounted at a side surface of the circuit board  10  with the connection member  50 . The connection member  50  may be formed with a transmission line  52  and a wire bonding unit  54 . The transmission line  52  is located between the electronic element  40  and the optical element  30 , and the transmission line  52 , the electronic element  40 , and the optical element  30  are connected by the wire bonding unit  54 . Therefore, the transmission line  52  is located between a side surface and an upper surface of the circuit board  10 , i.e., at a corner of the circuit board  10 . 
     A corner of the circuit board  10  in which the transmission line  52  is located may be a curvedly formed curved surface  60 . When the transmission line  52  is located at a vertically formed surface, if an electric signal is transferred to the electronic element  40  along the transmission line  52  that is located at the curved surface  60 , a loss of an electric signal or heat occurring on the transmission line  52  can be reduced. 
       FIG. 2  is a cross-sectional view illustrating a portion of an optical module according to a first exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , the transmission line  52  is located at a curvedly formed corner of the circuit board  10 , and a glass rod  62  is inserted into the curvedly formed curved surface  60  of the circuit board  10  to form a curved shape. A description of the configuration of the optical cable array  20  will be omitted. 
     The glass rod  62  is inserted into a corner portion of the circuit board  10 , and the transmission line  52  is located at a surface of the glass rod  62 . The glass rod  62  may function as a dielectric material. 
     After coating an electrode at the glass rod  62 , the transmission line  52  may form a transmission line in a pattern in the glass rod  62  using infrared ray short pulse laser. 
     In more detail, in the transmission line  52 , titanium, nickel, or chrome having good adhesion with the glass rod  62  is used, and the transmission line  52  may be plated with a method such as Au sputtering or Au plating. Further, according to a bandwidth of the transmission line  52  and a line width and a line gap that are determined according to an impedance matching structure such as a coplanar waveguide and a microstrip line, the transmission line  52  may be produced using a short pulse laser having a pulse width of several nanoseconds (ns) of an infrared ray wavelength band of 1064 nm or more having good transmittance and a low absorption rate to glass. 
     When the transmission line  52  is produced in this way, damage is reduced in the glass rod  62  that performs a dielectric material function and thus an impedance change of the transmission line  52  is minimized, thereby reducing a signal loss and noise. 
     Further, because the transmission line  52  may be directly formed in the glass rod  62  without separate mask production, cost can be reduced and a path can be smoothly changed through the transmission line  52  that is disposed along a circumference of the glass rod  62  and thus a bandwidth loss can be minimized. Further, by simplifying a production process, an optical module can be formed with a low price. Further, the signal transmission line  52  of various angles can be implemented according to a shape of the glass rod  62  and an electrode. 
       FIG. 3  is a cross-sectional view illustrating a portion of an optical module according to a second exemplary embodiment of the present invention. 
     Referring to  FIG. 3 , a quarter of a glass rod  64  is inserted into a corner of a circuit board  10 . The corner of the circuit board  10  is vertically formed, and the quarter of the glass rod  64  is coupled to the corner of the circuit board  10 . Therefore, the optical module according to a second exemplary embodiment has a merit that the quarter of the glass rod  64  can be easily inserted into the circuit board  10  and that an optical module  100  can be formed in a small size, compared with the optical module  100  of the first exemplary embodiment. 
       FIG. 4  is a cross-sectional view illustrating a portion of an optical module according to a third exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , a glass rod  62  is inserted into a side surface of a circuit board  10 , an electronic element  40  is located at a upper surface of the circuit board  10 , and an optical element  30  may be located at a lower surface of the circuit board  10 , which is a direction opposite to that of the electronic element  40 . 
     The optical element  30  is located at a lower surface of the circuit board  10 . Therefore, because the optical element  30  may receive an input of an optical signal at a lower surface of the circuit board, the optical waveguide array  20  (see  FIG. 1 ) and the circuit board  10  can be variously connected. By inserting the glass rod  62  into a side surface of the circuit board  10 , the optical module can be easily produced. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 &lt;Description of symbols&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 100: optical module 
                 10: circuit board 
               
               
                   
                  20: optical waveguide array 
                 22: optical waveguide 
               
               
                   
                  30: optical element 
                 40: electronic element 
               
               
                   
                  50: connection member 
                 52: transmission line 
               
               
                   
                  54: wire bonding unit 
                 60: curved surface 
               
               
                   
                  62: glass rod 
                 64: quarter of glass rod