Abstract:
The present invention provides an optical transceiver with a structure that is able to cope with both the heat-dissipation and the optical coupling of the sub-assembly with a butterfly package. The optical transceiver includes a frame, a receptacle member, a transmitter optical sub-assembly, a receiver optical sub-assembly, a substrate and a cover. At least one of sub-assemblies provides, what is called, a butterfly package assembled with the receptacle member. The assembly of the receptacle member with the sub-assembly is fixed to the frame with an elastomer put between the receptacle member and the frame. The sub-assembly is assembled with the receptacle member as satisfying the optical alignment, while, the assembly of the receptacle member and the sub-assembly is fixed to the frame in a unit. Accordingly, the optical alignment and the fixing to the frame are consistently satisfied.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application No. 60/741,080, titled “Optical transceiver” filed Dec. 1, 2005, which is incorporated herein by a reference. 

   SUMMARY OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical transceiver, in particular, the invention relates to a new arrangement of an optical transceiver installing a sub-assembly with, what is called, a butterfly package. 
   2. Related Prior Art 
   The optical transceiver includes a transmitter optical sub-assembly (TOSA), a receiver optical sub-assembly (ROSA), a substrate mounting an electronic circuit coupled with the TOSA and the ROSA to process electrical signals, and a frame for mounting the substrate. The electronic circuits are, for instance, a driver for driving a laser diode installed within the TOSA, a signal re-generator for amplifying an electrical signal converted by a photodiode installed within the ROSA and extracting a clock and a data contained in the received optical signal, and a circuit for controlling the driver and the re-generator. 
   Recently, the specification of such optical transceiver, in particular, outer dimensions and electrical functions, becomes common in the market by defining, what is called, a multi-source agreement (MSA) to make the replacement of the transceiver possible even when the vendor or the manufacturer thereof is different. One of such MSA is the XFP standard, which is the 10 Gbps small form factor pluggable module multi-source agreement and set in Apr. 2, 2003.  FIG. 1  is a perspective view showing the XFP transceiver mounted on the host board. The host board provides a metal cage  111  thereon. The aperture  112  of the cage exposes in the bezel  102 , into which the optical transceiver  120  is inserted. In the rear end of the optical transceiver  120  is provided with an electrical plug  121 . By engaging this electrical plug  121  with an electrical connector  103  provided in the deep end of the cage  111 , an electrical communication, for instance, the transmitting of electrical signals and the providing power supplies, between the transceiver  120  and the host  101  can be realized. On the upper surface of the cage  111  is sometimes attached with a heat-radiating fin  113  with a clip  114 . 
   Various inner structures of the optical transceiver are well known and proposed in such MSAs. The conventional optical transceiver generally uses sub-assemblies with, what is called, a co-axial package. Because, the transmission rate is limited within a few giga-bit per seconds (Gbps) and the power consumption of the electronic components is not so large. To conduct the heat from the electronic components by adhering thermal sheets inserting between the components and the frame of the transceiver may effectively dissipate heat to maintain the performance of the electronic components and the semiconductor optical devices installed therein. 
   However, recent transmission rate reaches 10 Gbps or more. The power consumption by the electronic devices becomes quite large to be operable in such high frequency. Further one modified application is proposed that such pluggable transceiver is applied in the wavelength division multiplexed (WDM) communication that precisely defines the wavelengths of optical signals. Thus, the optical transceiver is inevitable to install a temperature controlling device to precisely control and maintain the emission wavelength of the laser diode installed within the sub-assembly. The conventional co-axial package for the TOSA is hard to install such temperature controlling device therein from a viewpoint of the package size. Accordingly, the butterfly package with a rectangular shape is applied to such a functional optical transceiver. For the ROSA, the situation of the increasing the heat generation is similar to those confronted for the TOSA. The butterfly package is also sometimes inevitable for the ROSA. 
   The butterfly package brings an inconsistent subject. That is, a primary object to apply the butterfly package is to install a component that generates large heat, accordingly, the outer surface of the butterfly package is necessary to be adhered to somewhere to effectively conduct heat generated within the package. 
     FIG. 2  is a perspective view showing the sub-assembly with the butterfly package. The sub-assembly includes a body portion  210  with a rectangular shape and a sleeve portion  220 . A plurality of lead terminals  211  extrudes from rear side wall  212  of the body portion  210 . The sleeve portion  220  extrudes from a side  213  opposite to the side wall  212  and a tip thereof provides a sleeve  221 . This sleeve  221  receives a ferrule, which is not shown in  FIG. 2 , and an optical fiber held in a center of the ferrule optically couples with an optical device installed within the body portion  210 . The optical device is optically aligned with the center of the aperture  222  of the sleeve  221 . In the sub-assembly shown in  FIG. 2 , the bottom  214  of the body portion  210  is necessary to be adhered to the frame of the transceiver to conduct heat generated by components installed within the body portion  210 . 
   On the other hand, to optically couple the optical device with the optical fiber, in other words, to optically align the sleeve with the optical fiber, the sleeve  221  is necessary to be positioned with respect to the optical receptacle that is a part of the frame of the transceiver. By mating the optical plug, which contains the ferrule, with the optical receptacle in the transceiver, which mates the ferrule in the optical plug with the sleeve, the optical device in the body portion  210  can optically couple with the optical fiber in the ferrule. In  FIG. 1 , two apertures illustrated in the end portion of the optical transceiver  120  correspond to the optical receptacle for the transmitter and the receiver, respectively. 
   Thus, in the butterfly package, the bottom of the body portion is necessary to be adhered to the frame and, at the same time, the sleeve is necessary to be defined in the position thereof with respect to the frame to optically couple with the optical plug. However, some tolerance in physical dimensions is inevitably attributed to such mechanical components. The conventional sub-assemblies with the co-axial package have solved the subject of the heat dissipation by interposing a thermal sheet made of elastic resin between the sub-assembly and the frame. The elasticity of the resin may compensate the tolerance; accordingly, the positional relationship against the frame is determined primarily by the optical coupling of the sub-assembly with the optical fiber. However, the sub-assembly with the butterfly package is necessary to enhance the heat dissipating efficiency compared to that of the co-axial package, accordingly, the bottom surface of the butterfly package must be adhered to the frame, which becomes unable for the thermal sheet to compensate the mechanical tolerance. For the butterfly package, it is required to define the positional relationship against the frame by two points, namely, the sleeve portion and the bottom of the body portion of the package, which induces a mechanical stress at the connecting point of the sleeve portion with the body portion of the package. 
   A Japanese patent application published as JP-2005-227783A has disclosed a structure of the optical transceiver, in which the sub-assembly is adhered to the bottom surface thereof to the frame of the transceiver after the sleeve of the sub-assembly is optically aligned with the optical receptacle. Another Japanese patent application published as JP-2006-259720A has disclosed a similar structure of the optical transceiver, in which the sleeve is first aligned with the receptacle and the bottom of the sub-assembly is next adhered to the frame by rotating the assembly of the optical receptacle with the sub-assembly around the longitudinal axis of the optical transceiver by dividing the optical receptacle from the frame. 
   Thus, an aspect of the present invention is to provide a simple structure of the optical transceiver that, dividing the optical receptacle and the frame of the transceiver, assembles the unit integrating the optical receptacle with the sub-assemblies with the frame. 
   SUMMARY OF THE INVENTION 
   The optical transceiver according to the present invention comprises a receptacle member, sub-assemblies, and a frame. The receptacle member includes an optical receptacle that mates with an optical connector. The sub-assemblies each installs a semiconductor optical device that optically couples with the optical fiber secured in the optical connector by being assembled with the receptacle member. The frame installs the receptacle member and the sub-assemblies. At least one sub-assembly provides, what is called, a butterfly package with a rectangular body portion installing the semiconductor optical device and a cylindrical sleeve portion extending from one side wall of the body portion. The receptacle member includes a first portion that includes the optical receptacle and a second portion that continues to the first portion and provides openings to receive the sleeve portion of the sub-assemblies. The present invention has a feature that the receptacle member is fixed to the frame by putting a resin member, typically an elastomer, between the receptacle member and the frame at the second portion. Moreover, the frame of the transceiver according to the present invention puts the receptacle member between side walls of the frame, and the side walls each provides a groove in an inner surface thereof, while, the outer side surface of the side wall of the receptacle member provides a projection to be mated with the groove of the side wall of the frame. The receptacle member with the sub-assemblies integrated therewith may be movable between the side walls of the frame by sliding the projection of the outer side surface within the groove of the inner surface of the side wall of the frame. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a partially broken perspective view showing the pluggable optical transceiver and the host board installing the pluggable optical transceiver; 
       FIG. 2  is a perspective view showing the sub-assembly with a butterfly package; 
       FIG. 3  is an exploded view of the optical transceiver according to an embodiment of the present invention; 
       FIGS. 4A and 4B  are perspective drawings of the receptacle member according to the present invention, which are viewed from different directions; 
       FIG. 5  is a perspective view of the frame according to an embodiment of the present invention; 
       FIG. 6  is a perspective view of the cover of the optical transceiver according to an embodiment of the present invention; 
       FIG. 7  is a partially broken perspective view showing the assembly of the receptacle member, the sub-assembly with the butterfly package and the frame; and 
       FIG. 8  is a perspective view of the optical transceiver after the completion of the assembly according to an embodiment of the invention. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 3  is an exploded view of an optical transceiver according to the present invention. The optical transceiver  1  primarily comprises a frame  10 , a substrate  50 , a transmitter optical sub-assembly (TOSA)  30 , a receiver optical sub-assembly (ROSA)  40 , a receptacle member  20 , and a cover  60 . Since the transceiver shown in  FIG. 1  provides both the TOSA  30  and the ROSA  40  each able to couple with the optical fiber independently, an optical communication can be realized in the full-duplex mode. Although  FIG. 3  illustrates the ROSA  40  with a box shaped package, functions and advantages of the present invention are independent of the shape of the package of the ROSA  40  as described below. 
   The frame  10  is made by aluminum die-casting and mounts the receptacle member  20 , the TOSA  30 , the ROSA  40 , and the substrate  50  from the front side thereof to the rear side in this order. The frame  10  further assembles with the cover  60  to enclose the TOSA  30 , the ROSA  40  and the substrate  50 . The front corresponds to a side where the receptacle member  20  is provided, while, the rear corresponds to a side where a plug connector  50   b  is formed on the substrate. The frame  10  covers sides of the receptacle member  20  in the front side and extends to the front end of the transceiver  10  to abut the front surface  11   f  of the frame  10  against the flange  20   c  of the receptacle member  20 . 
   The receptacle member  20  is made of resin plated with metal or metal alloy including a die-casting zinc alloy. The front side of the receptacle member  20  provides an optical receptacle with two openings,  21   a  and  21   b . Although not explicitly shown in  FIG. 3 , the receptacle member  20  forms openings in the rear wall thereof into which sleeves,  30   b  and  40   b , of the optical sub-assemblies,  30  and  40 , are inserted. By inserting the sleeve of the optical sub-assembly into the opening, the position of the sleeve can be determined within the optical receptacle, accordingly, the optical devices installed within the body portion,  30   a  and  40   a , may optically couple with the optical fibers secured in the optical connector to be mated with the optical receptacle,  21   a  and  21   b.    
   Two sub-assemblies,  30  and  40 , provide butterfly packages with body portions,  30   a  and  40   a , with a rectangular shape and cylindrical sleeve portions,  30   b  and  40   b , extruding from one side wall of the body portion. At least a portion coming in contact with the body portion,  30   a  or  40   a , of the sleeve portion,  30   b  or  40   b , is necessary to be made of metal, while, other portions, namely, tip portions of the sleeve,  30   b  or  40   b , may be made of metal or resin. A plurality of lead terminals for the electrical signal,  30   c  or  40   c , protrude from the rear wall of the body portions,  30   a  or  40   a . Although not explicitly illustrated in  FIG. 3 , the TOSA  30  further provides other lead terminals protruding from one side wall thereof with a flexible printed circuit (FPC) board to electrically connect the lead terminals to the circuit board. Interconnections formed on the FPC board are provided for the low-frequency or DC signals, such as the power supply line to the thermo-electric device installed within the TOSA  30  and the signal from the temperature sensor. 
   The substrate  50  mounts an electronic circuit thereon. The circuits for the TOSA  30  are an LD driver circuit for driving the semiconductor laser diode (LD) installed within the body portion  30   a , a temperature controller to control the temperature of the thermo-electric cooler also within the body portion  30   a , and an auto-power controller (APC) to keep the optical output power of the LD. On the other hand, the circuits for the ROSA  40  are a main amplifier to amplify a signal output from the ROSA  40 , a clock extractor to extract the clock component from the amplified signal, and a data re-generator to extract the data component from the amplified signal based on the extracted clock. When the ROSA  40  installs an avalanche photodiode (APD) as a light-receiving device, a bias controlling circuit for this APD may be mounted on the substrate  50 . On the rear end of the substrate  50  is provided with the plug connector  50   b  to be mated with the connector within the cage. A hot pluggable function, namely, the transceiver may be inserted into or extracted from the cage without shutting down the host system, can be obtained by forming the electrode pattern on the substrate in a predetermined shape. 
   The cover, made of metal plate, electrically shields the sub-assemblies,  30  and  40 , and the substrate  50  by enclosing these parts between the frame  10 . A portion of the side wall of the cover  60  provides a cut to expose the latching lever therefrom to latch the transceiver  1  with the cage. 
   Next, details of the members mentioned above will be described. 
   (Receptacle Member) 
     FIGS. 4A and 4B  are perspective drawings viewed from the front upper side and the rear upper side, respectively. The receptacle member  20 , made of resin plated with electrically conducting material in a whole surface thereof, includes a first portion  20   a  forming the optical receptacles,  21   a  and  21   b , and a second portion  20   b  with the rear wall that forms two openings,  22   a  and  22   b , into which the sleeve portions,  30   b  and  40   b , of the sub-assemblies,  30  and  40 , are inserted. 
   The first portion  20   a  is divided by the center partition  20   d  to form the optical receptacle  21   a  for the transmission and &#39;that  21   b  for the reception. Physical dimensions of the optical receptacles,  21   a  and  21   b , are precisely defined by the specification of the optical connector to be mated with these optical receptacles. Both side walls of the front end of the first portion  20   a  form flanges  20   c  to define the front end of the optical transceiver  1 . Both side walls secluded from the flange  20   c  forms projections  21   e  to mate the receptacle member  20  with the frame  10 . To put the receptacle member  20  between the front walls  11   f  of the frame  10  and to fit these projections  21   e  in the grooves  11   a  formed in the inner surface  11   f  of the frame, which abuts the front end surface of the frame  10  against the rear surface of the flange  20   c , determines the position of the receptacle member  20  in the longitudinal direction. The projection  21   e  may slide within the groove  11   a , which enables an assembly of the sub-assemblies,  30  and  40 , with the receptacle member  20  to be fixed with the frame  10  as maintaining the optical coupling between the receptacle member  20  with the sub-assemblies,  30  and  40 . 
   The second portion  20   b  provides two openings,  22   a  and  22   b , into which the sleeve portions,  30   b  and  40   b , of the sub-assemblies,  30  and  40  are inserted. By setting the diameter of the openings,  22   a  and  22   b , slightly smaller than the outer diameter of the sleeve portions,  30   b  and  40   b , the sleeve portions can be automatically determined in their position within each optical receptacle,  21   a  or  21   b , without any backlash. That is, the sleeve portions,  30   b  and  40   b , in tips thereof does not move in wobbling. The second portion  20   b  also forms a step  22   e  with 0.3 mm height and 1.5 mm depth in the upper end portion thereof. Although not illustrated in  FIGS. 4A and 4B , an elastomer is applied along this step  22   e  with a thickness of about 0.5 mm. This elastomer operates as an elastic member when the receptacle member  20  with the sub-assemblies,  30  and  40 , are set on the frame  10  such that the bottom of the body portions,  30   a  and  40   a , of the sub-assemblies are adhered to the corresponding position on the frame  10 , which absorbs the mechanical deformation induced between the sleeve portions,  30   b  and  40   b , and the body portions,  30   a  and  40   a , that is left as a subject to be solved in conventional transceivers. The step  22   e  abuts against the surface  11   b  of the frame  10  when the receptacle member  20  is set between side walls  11   f  of the frame  10 . Thus, in addition to the combination of the projection  20   e  and the groove  11   a  formed in the inner wall surface  11   f  of the frame  10 , which is already explained, the step  22   e  abutting the front edge of the frame  10  determines the relative position of the receptacle member  20  with respect to the frame  10 . Moreover, the electrically conductive elastomer may enhance the EMI shield characteristic of the transceiver  1 . 
   The surface  22   f  opposite to the step  22   e , which is the bottom side of the receptacle member  20 , is formed in flat for the cover  60  to come in securely contact thereto. The tab  60   f , which is illustrated in  FIG. 6 , comes in contact to this flat surface  20   f  to make the cover  60  in electrical contact to the receptacle member  20 . 
   (Frame) 
     FIG. 5  is a perspective drawing of the frame  10  viewed from the front side. The frame  10  includes first to fourth portions,  10   a  to  10   d , from the front side in this order. The first to fourth portions,  10   a  to  10   d , receive the receptacle member  20 , two sub-assemblies,  30  and  40 , the substrate  50 , and the connector plug, respectively. 
   The first portion  10   a  provides a space  11  surrounded by two side walls  11   f . As previously described, the inner surface of the side wall  11   f  forms the groove  11   a  to receive the projection  21   e  formed in the outer surface of the side wall  20   f  of the receptacle member  20 . In the deep end of the space  11  is formed with the surface  11   b  to be abutted against the rear surface of the receptacle member  20 . When the receptacle member  20  is assembled with the frame  10 , the elastomer applied along the step  22   e  of the receptacle member  20  is to be abutted against this surface and compressed. Accordingly, the elastomer shows the elastic function. In the outer surface of the side walls  11   f  are formed with an opening  11   e  and a grove  11   d , which are mechanisms to rotate the bail, not illustrated in  FIG. 5 , to release the engagement of the transceiver  1  with the cage. 
   In a border between the first and second portions,  10   a  and  10   b , adjacent to the abutting surface  11   b  provided with the elastomer is formed with saddles  12   c  to hold the sub-assemblies,  30  and  40 , although the saddle for the TOSA  30  is hidden by the side wall  11   f . Moreover, two depressions,  12   d  and  12   e , to receive the sub-assemblies,  30  and  40 , are formed in adjacent to each saddle. In the present invention, since the receptacle member  20  provides the elastomer that has an elastic function, the stress maybe escaped from concentrating on the root of the sleeve portions,  30   b  and  40   b , even the body portions,  30   a  and  40   a , are pressed to the depressions,  12   d  and  12   e . Other mechanisms,  12   a  and  12   b , provided in the outer surface of the side wall of the second portion  10   b  are grooves for receiving the lever to release the latching the transceiver with the cage, which operates with the bail attached in the outer surface of the side wall  11   f  in the first portion  10   a.    
   The third portion  10   c  installs the substrate  50 . The third portion  10   c  provides a primary surface  13   a , a plurality of depressions  13   b  gouged out the primary surface  13   a , and a pair of projections  13   c  each formed in the sides thereof. The substrate  50  provides a pair of cuts in both sides thereof. By putting the substrate  50  on the step  13   e  as fitting the cuts in the substrate  50  with the projections  13   c  on the step  13   e , the substrate  50  is positioned and fixed to the frame  10 . Moreover, by abutting the front end of the substrate  50  against the rear end of both side walls in the second portion  10   b , the longitudinal position of the substrate  50  may be determined. The depressions  13   b  receive the ICs mounted on the substrate  50 . By putting thermal sheets within the depressions, a thickness of which may compensates the height of the step  13   e , the depth of the depression  13   b , and the thickness of the IC within the depression  13   b , the heat-dissipating path from the IC to the frame  10  can be secured. 
   Between the third portion  10   c  and the fourth portion  10   d  is provided with a pair of posts  14   c  extending from the side walls in the fourth portion  10   d . By abutting the finger  60   i  formed in the rear end of the cover  60  against this post  14   c  and pressing the substrate  50  with the tip of the finger  60   i , the substrate  50  may be fixed to the frame  10 . Moreover, the fourth portion  10   d  provides a flat portion  14   a  between both side walls  14   b , which receives the plug connector  50   b  formed in the rear end of the substrate so as to be substantially in parallel with this flat surface. 
   (Cover) 
     FIG. 6  is a perspective view of the cover  60 . The cover  60  is made of metal plate of stainless steel by the cutting and the bending. No welding or gluing is carried out. In  FIG. 6 , the right hand side corresponds to the front side of the transceiver  1 . The side of the cover  60  is divided into two portions by the cut  60   d . In the front side wall  60   j  is provided with an opening  60   c  to be fitted with the projection  11   c  formed in the outer surface of the side wall of the first portion  10   a , while, the rear side wall  601  forms two openings,  60   a  and  60   b , to be fitted with the projections,  12   f  and  13   f , formed in the second  10   b  and third  10   c  portions of the frame  10 . At the same time of the fittings, the finger  60   h  and another finger  60   i  formed in the rear end of the cover  60  press the substrate  60  against the frame  10 . That is, the substrate  50  is not only mounted in the primary surface thereof on the step  13   e  but also pressed against the step  13   e  by the cover  60 . 
   The bend  60   e  formed in the rear end of the cover  60  prevents the connector plug from miss-inserting into the connector in the cage by abutting the bend  60   e  against the front edge of the connector when the transceiver  1  is inserted into the cage in upside-down. The front portion of the cover  60  transversely forms a slit  60   g  to reinforce the mechanical strength of the cover  60 . Moreover, the center opening  60   k  enables to observe the inside of the transceiver  1  after the completion of the assembly. A plurality of fingers  60   f  in the front side, as already explains, come in electrically contact with the receptacle member  20  to secure the ground potential of the receptacle member  20 . That is, the finger  60   f  is formed by cutting U-shaped slits in the cover  60  and bending a portion inside this U-shaped slit inward. These fingers  60   f  may come in electrically contact with the surface  22   f  of the receptacle member  20  in plural points after the assembly of the cover  60  with the frame  10 , which secures the electrical contact between the receptacle member  20  and the cover  60 . 
   (Elastomer) 
     FIG. 7  is a partially broken perspective view of the assembly of the TOSA  30  with the receptacle member  20  and the frame  10 . The sleeve portion  30   b  of the TOSA  30  passes through the opening  22   a  in the second portion of the receptacle member  20 . The body portion  30   a  of the TOSA is set within the depression  12   e  of the frame  10  as the bottom surface thereof comes in contact to the frame  10 . The elastomer  25  is pressed between the step  22   e  of the receptacle member  20  and the flat surface  11   b  of the frame  10 . According to the structure shown in  FIG. 7 , the sleeve  30   b  is precisely positioned with respect to the receptacle member  20  so as to satisfy the specification of the optical receptacle  21   a . At the same time, the body portion  30   a  of the TOSA  30  is adhesively fixed to the depression  12   e  of the frame  10 . Because the receptacle member  20  and the frame are independently to each other and the former member  20  is assembled with the latter member  10 , so to speak, in a floating mode, the mechanical stress possibly caused between the sleeve portion  30   b  and the body portion  30   a  can be excaped. The floating mode can be realized by the elastomer  25  put between the frame  10  and the receptacle member  20 . 
   The embodiment described above uses the elastomer  25  to realize the floating assembly between the frame  10  and the receptacle member  20 . However, the present invention is not restricted to the elastomer. Any materials to have an elastic function may be applicable to the present invention. For instance, a leaf spring put between the frame  10  and the receptacle member  20  may show a similar function. Moreover, the receptacle member  20  may integrally build the leaf spring made of the same material with the receptacle member  20 . 
     FIG. 8  illustrates a completion of the optical transceiver  1  of the present invention. The while upper surface of the transceiver  1  expose the bottom of the frame  10 . Accordingly, when the transceiver  1  is inserted into the cage with the heat dissipating fin, as shown in  FIG. 1 , the heat generated in the sub-assemblies,  30  and  40 , and ICs mounted on the substrate  50  may be directly conducted to the cage. Since the sub-assemblies,  30  and  40 , are installed on the frame  10  so as to adhere the bottom of the body portion thereof to the depression of the frame  10 , which secures the effective heat-dissipating path from the sub-assemblies to the frame  10 , and the bottom surface of the frame  10  directly comes in contact to the cage. Thus, the heat generated in the sub-assemblies,  30  and  40 , may easily and effectively radiate outside the transceiver  1 . 
   Further, since the frame is made of metal die-casting, even when the smooth insertion and the smooth extraction of the optical transceiver is not obtained due to the touching to the heat-dissipating fin of the cage, the transceiver, in particular, the substrate and the sub-assemblies, may be escaped from the mechanical deformation or damage. The optical transceiver according to the present invention may be assembled in all parts thereof by fitting, which can simplify the assembly to reduce the production cost.