fig3 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 fig1 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 fig3 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 fig3 , 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 fig3 , 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 . fig4 a 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 fig4 a 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 fig6 , comes in contact to this flat surface 20 f to make the cover 60 in electrical contact to the receptacle member 20 . fig5 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 fig5 , 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 . fig6 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 fig6 , 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 . fig7 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 fig7 , 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 . fig8 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 fig1 , 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 .