Patent Publication Number: US-2009232173-A1

Title: Optical semiconductor apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2008-066288, filed on Mar. 14, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an optical semiconductor apparatus that outputs light. 
     2. Description of the Related Art 
     In recent years, accompanying the increase in communication needs brought about by broadband services, advances in optical communication networks covering longer distances and having greater capacities have been made and the development of high-speed, large-capacity wavelength division multiplexing (WDM) is progressing. WDM is a transmission scheme in which optical signals of differing wavelengths are transmitted simultaneously in a single optical fiber. Meanwhile, with the rapid expansion of the Internet and the rise in large-volume content, a high-speed, high capacity optical communications network that further affords flexibility is needed. 
     Optical packet switching is a focus of technology for building such optical communications networks. Optical packet switching is the exchange of communication information packets entirely in the optical domain. In comparing optical packet switching to switching involving the conversion of an optical signal into an electrical signal, optical packet switching is not subject to electrical processing rate limitations; thereby enabling processing that maintains the optical propagation velocity. Hence, through the utilization of optical packet switching, high speed, high volume transmission becomes possible. 
     When optically switching optical signals in packet units, a gate switch that switches the optical signals between ON and OFF is employed. Gate switches that switch optical signals between ON and OFF under electrical control primarily include those that utilize the electroabsorption effect to vary absorption and those that vary the gain of the switch according to the driving current supplied to a semiconductor optical amplifier (SOA). 
     Electroabsorption-type gate switches have the disadvantage of a large loss even in a transmission state. On the other hand, SOAs are switches that vary the gain of the switch according to the driving current supplied. As light is amplified and output when the gate is ON, SOAs not only function as optical gates switching light ON and OFF, but further have a combined function of optical amplification. 
     Hence, SOAs have attracted attention as optical elements that perform high-speed switching with low optical signal loss. Further, the extinction ratio at gate ON/OFF is high for SOAs and amplification enables reduction of optical loss. As SOAs are optical elements formed by semiconductors, semiconductor integrated technology realizes the advantages of low cost and compact size. 
     The extinction ratio at gate ON/OFF is the ratio of the average optical intensity of a signal “ 1 ” “ 0 ” when the gate is ON and the average optical intensity of a signal “ 1 ” “ 0 ” when the gate is OFF. The greater the extinction ratio, the more clearly the ON/OFF state of the gate can be distinguished; therefore, interference by signals to other ports (crosstalk) is reduced, thereby reducing the encoding error rate. Optical semiconductor elements emitting light, such as SOAs and laser diodes (LDs), require driving currents of several hundred milliamperes. 
     Hence, power consumption of optical semiconductor elements ranges between 0.5 watts to 1 watt. When a SOA array formed by plural SOAs is employed, power consumption reaches up to several watts. Further, for optical semiconductor elements, output power characteristics with respect to power consumption decreases as temperature decreases. Therefore, to maintain the optical semiconductor element at a constant temperature, Peltier element is employed to adjust the temperature of the optical semiconductor element, as disclosed in Japanese Patent Application Laid-Open Publication No. H7-287130. 
       FIG. 15  is a front cross-sectional view of a conventional optical semiconductor apparatus.  FIG. 16  is a top view of an optical semiconductor element depicted in  FIG. 15 . A conventional optical semiconductor apparatus  150  includes an LD array  151  having plural LDs. Each of the LDs of the LD array  151  outputs light according to the driving current supplied. The LD array  151  is provided on a Peltier element  153  through a first stem  152 . 
     A lens  154  transmits lights emitted from the LD array  151 . The lens  154  is provided on the Peltier element  153  through a second stem  155 . When the Peltier element  153  controls the temperature, the size of the Peltier element  153  varies, thereby causing deviation in the relative positions of the light emitted from the LD array  151  and the lens  154  and hence, provision of both the LD array  151  and the lens  154  on the Peltier element  153  prevents the occurrence of optical coupling loss. 
     Concerning the assembly of the optical semiconductor apparatus  150 , the stem  152  and the stem  155  that are precision-manufactured by machined processing are arranged on the Peltier element  153  and fixed by soldering. On the stem  152 , the LD array  151  is arranged and on the stem  155 , the lens  154  is arranged, where the position of the optical axis of the light emitted from each of the LDs of the LD array and a central portion of the lens  154  substantially coincide. 
     While light is being emitted from the LD array  151 , the position of the lens  154  is determined such that the light transmitted by the lens  154  becomes collimated and the lens  154  is fixed on the stem  155  by laser welding or soldering. Thereafter, the position of an optical fiber array  156  is adjusted such that the light transmitted by the lens  154  is coupled with the optical fiber array  156  at a maximum rate. 
     With the conventional technology above, a problem arises in that the relative positions of the part supporting the LD array  151  of the stem  152  and the part supporting the lens  154  of the stem  155  are determined by the precision of the assembly of the stems  152  and  155  with respect to the Peltier element  153  and hence, the respective positions of the LD array  151  and the lens  154  cannot be adjusted with high precision. 
     Specifically, as the stem  152  and the stem  155  are fixed on the Peltier element  153  by soldering or the like, the distance from the Peltier element  153 , the angle with respect to the Peltier element  153 , etc. cannot be adjusted with high precision. Hence, the position of the lens  154  with respect to each of the lights emitted from the LD array  151  deviates in the direction of the x-axis, and/or is tilted about the x-axis and/or the z-axis. Thus, the light emitted from the LD array  151  cannot be aligned with the ends of the optical fiber array  156  with high precision and the transmission characteristics of the light output from the optical fiber array  156  degrades. 
     In particular, as depicted in  FIG. 16 , when the LD array  151  is employed, the coupling position of light  162  emitted from each of the LDs of the LD array  151  deviates in the direction of the x-axis as indicated by the reference numeral  161  in  FIG. 16 . Hence, with precision, the light  162  emitted from the LD array  151  cannot be coupled with the ends of the optical fibers of the optical fiber array  156  aligned in the direction of the y-axis. As a result, respective transmission characteristics of the channels of the optical fiber array  156  become non-uniform. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to at least solve the above problem in the conventional technologies. 
     An optical semiconductor apparatus according to one aspect of the present invention includes: an optical semiconductor element that outputs light; a lens that transmits light output from the optical semiconductor element; and a support member that is integrally formed and includes a first support supporting the optical semiconductor element, a second support supporting the lens, and an intermediate portion through which the first support and the second support are integrated. 
     The other objects, features, and advantages of the present invention are specifically set forth in or will become apparent from the following detailed description of the invention when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front cross-sectional view of an optical semiconductor apparatus according to a first embodiment; 
         FIG. 2  is a top view of an optical semiconductor element and a stem depicted in  FIG. 1 ; 
         FIG. 3  is a top view of a modified example of the optical semiconductor element depicted in  FIGS. 1 and 2 ; 
         FIG. 4  is a front cross-sectional view of the optical semiconductor apparatus according to a second embodiment; 
         FIG. 5  is a front view and a side view of a fixing ring depicted in  FIG. 4 ; 
         FIG. 6  is a front cross-sectional view of the optical semiconductor apparatus according to a third embodiment; 
         FIG. 7  is a front cross-sectional view of the optical semiconductor apparatus according to a fourth embodiment; 
         FIG. 8  is a front cross-sectional view of the optical semiconductor apparatus according to a fifth embodiment; 
         FIG. 9  is a top view of the optical semiconductor element and the stem depicted in  FIG. 8 ; 
         FIG. 10  is a front cross-sectional view of the optical semiconductor apparatus according to a sixth embodiment; 
         FIG. 11  is a top view of the optical semiconductor element and the stem depicted in  FIG. 10 ; 
         FIG. 12  is a top view of a modified example of the optical semiconductor element depicted in  FIGS. 10 and 11 ; 
         FIG. 13  is a front cross-sectional view of the optical semiconductor apparatus according to a seventh embodiment; 
         FIG. 14  is a front view and a side view of an optical semiconductor element and a stem depicted in  FIG. 13 ; 
         FIG. 15  is a front cross-sectional view of a conventional optical semiconductor apparatus; and 
         FIG. 16  is a top view of an optical semiconductor element depicted in  FIG. 15 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the accompanying drawings, exemplary embodiments according to the present invention are explained in detail below. 
     With reference to the accompanying drawings, exemplary embodiments of an optical semiconductor apparatus according to the present invention are explained in detail below. 
       FIG. 1  is a front cross-sectional view of an optical semiconductor apparatus according to a first embodiment.  FIG. 2  is a top view of an optical semiconductor element and a stem depicted in  FIG. 1 . In the drawings, the z-axis indicates the optical propagation direction. The zx-plane indicates a front aspect of the optical semiconductor apparatus. The zy-plane indicates an upper aspect of the optical semiconductor apparatus. As depicted in  FIG. 1 , an optical semiconductor apparatus  10  according to the first embodiment includes a casing  11 , an LD  12 , an element carrier  12   a,  a lens  13 , a stem  14 , a Peltier element  15 , and an output unit  16 . 
     The optical semiconductor apparatus  10  outputs light according to the driving current supplied. An opening  11   b  for outputting light is provided in the casing  11 . Reference numeral  11   a  indicates a cover of the casing  11 . The LD  12 , the element carrier  12   a,  the lens  13 , the stem  14 , the Peltier element  15 , and the output unit  16  are provided inside the casing  11 . 
     The LD  12  is a semiconductor element that emits light. The LD  12  is mounted on the element carrier  12   a  and emits light having a power according to the driving current supplied. The element carrier  12   a  fixes the LD  12  and is a wiring substrate electrically connecting an electrode of the LD  12 . The element carrier  12   a  is fixed on the stem  14 . 
     The lens  13  transmits the light emitted from the LD  12 . For example, the lens  13  is a collimating lens that collimates the light output from the LD  12 . The lens  13  outputs the collimated light from the opening lib of the casing  11  to the output unit  16 . A lens holder  13   a  supporting the lens  13  is provided at the lens  13 . The lens  13  is fixed on the stem  14  via the lens holder  13   a.    
     The stem  14  is a support member supporting the element carrier  12   a  and the lens  13 . The stem  14  includes a first support  14   a,  a second support  14   b,  and an intermediate portion  14   c.  The first support supports the LD  12 . Specifically, the first support  14   a  has an upper aspect  14 A parallel to the yz-plane. The LD  12  is placed on the upper aspect  14 A (first support aspect) to be supported. 
     The second support  14   b  supports the lens  13 . Specifically, the second support  14   b  has, at a position where the light emitted from the LD  12  is transmitted, a through-hole of a size corresponding to the size of the lens  13  and into which the lens holder  13   a  is inserted to support the lens  13 . The first support  14   a  and the second support  14   b  are integrated via the intermediate portion  14   c.    
     Further, a width of the intermediate portion  14   c  may be smaller than a width of the first support  14   a  and the second support  14   b  in at least one direction (a direction on the xy-plane) perpendicular to the orientation of arrangement (direction of the z-axis) of the first support  14   a,  the intermediate portion  14   c,  and the second support  14   b.  In the configuration depicted in  FIG. 1 , a width of the intermediate portion  14   c  is smaller than a width of the first support  14   a  and the second support  14   b  in the direction of the x-axis. 
     Thus, thermal conductivity of the intermediate portion  14   c  can be made lower than the thermal conductivity of the first support  14   a  and the second support  14   b.  As a result, heat transferred to the Peltier element  15  from the second support  14   b  through the intermediate portion  14   c  can be reduced. Further, though not depicted, the stem  14  may be configured such that a width of the intermediate portion  14   c  is smaller than a width of the first support  14   a  and the second support  14   b  in the direction of the y-axis. 
     A lower aspect of the Peltier element  15  is in contact with and fixed to an interior wall of the casing  11 . Further, an upper aspect of the Peltier element  15  is in contact with and fixed to a lower aspect of the stem  14 . The Peltier element  15  dissipates, to the lower aspect in contact with an interior wall of the casing  11 , heat of the upper aspect in contact with the stem  14 . Thus, heat from the stem  14  is dissipated to the casing  11  and the stem  14  is cooled. By cooling the stem  14 , the LD  12  fixed on the stem  14  is cooled. 
     The output unit  16  is provided at the opening  11   b  on the external side of the casing  11 . The output unit  16  includes an isolator  17 , a lens  18 , and an optical fiber  19 . The isolator  17  transmits the light from the lens  13  to the lens  18 . In addition, the isolator  17  blocks light traveling from the lens  18  toward the lens  13 . The lens  18  converges, to an end of the optical fiber  19 , the light traveling from the lens  13  and through the isolator  17 . The optical fiber  19  outputs, to an external destination, the light converged by the lens  18 . 
     Thus, according to the optical semiconductor apparatus  10  of the first embodiment, through integration of the first support  14   a  and the second support  14   b,  relative positions of the first support  14   a  and the second support  14   b  can be adjusted with high precision by fabrication of the system  14 . As a result, the light emitted from the LD  12  can be coupled with the end of the optical fiber  19  with high precision and the transmission characteristics of the light output from the output unit  16  can be improved. 
       FIG. 3  is a top view of a modified example of the optical semiconductor element depicted in  FIGS. 1 and 2 . As depicted in  FIG. 3 , the optical semiconductor element that emits light, i.e., the LD  12  depicted in  FIGS. 1 and 2 , may be substituted with an LD array  31  having plural LDs. The LDs of the LD array  31  are arrayed in the direction of the y-axis and are fixed to the stem  14  by the element carrier  12   a.    
     In this case, in place of the optical fiber  19  depicted in  FIG. 1 , an optical fiber array (not depicted) is provided having plural optical fibers arrayed in the direction of the y-axis. Lights emitted from the LD array  31  are respectively coupled to ends of the optical fibers of the optical array and are output to an external destination by the optical fibers. 
     According to the optical semiconductor apparatus  10 , the coupling position of the each of the lights output from the LD array  31  can be adjusted with precision in the direction of the x-axis. Therefore, as depicted by reference numeral  32 , respective coupling positions of lights  33  emitted from the LD array  31  are easily aligned in a straight line along the direction of the y-axis. As a result, with precision, each of the lights emitted can be coupled with the ends of the optical fibers of the optical fiber array aligned along the direction of the y-axis. Thus, the respective transmission characteristics of the channels of the optical fiber array can be made uniform. 
       FIG. 4  is a front cross-sectional view of the optical semiconductor apparatus according to a second embodiment.  FIG. 5  is a front view and a side view of a fixing ring depicted in  FIG. 4 . In  FIG. 4 , components identical to those depicted in  FIG. 1  are given identical reference numerals and description thereof is omitted. As depicted in  FIG. 4 , the optical semiconductor apparatus  10  according to the second embodiment has the configuration of the optical semiconductor apparatus  10  according to the first embodiment with the addition of a fixing ring  41 . 
     The second support  14   b  includes an aspect  14 B (second support aspect) oriented perpendicular to the upper aspect  14 A (first support aspect) of the first support  14   a  on which the LD  12  is placed. The fixing ring  41  is positioning member that holds the lens  13  and positions the lens  13  with respect to the second support  14   b.  The fixing ring  41  has an aspect  41 A that is fixed in contact with the aspect  14 B of the second support  14   b.    
     The lens  13  and the lens holder  13   a  are arranged in a space  41   a  (refer to  FIG. 5 ) of the fixing ring  41  and are fixed and held by the fixing ring  41 . At the time of assembly of the optical semiconductor apparatus  10 , the aspect  41 A of the fixing ring  41  is not fixed to the aspect  14 B of the second support  14   b.  Thus, the fixing ring  41  is slidable in the direction of the xy-plane. 
     In this state, the LD  12  is caused to emit light and the light output from the optical fiber  19  is monitored while the fixing ring  41  is slid. The position of the fixing ring  41  with respect to the second support  14   b  is determined as the position where the monitored light has the greatest power. Thereafter, the aspect  41 A of the fixing ring  41  is fixed by, for example, laser welding to the aspect  14 B of the second support  14   b.    
     Thus, the lens  13  can be fixed to the second support  14   b  in a state where the position of the lens  13  on the xy-plane is adjusted with high precision with respect to the light from the LD  12 . Here, a configuration in which the LD  12  is provided as an optical semiconductor apparatus that emits light has been described; however, the LD  12  may be substituted with the LD array  31  (refer to  FIG. 3 ). In this case, in place of the optical fiber  19 , an optical fiber array having plural optical fibers arrayed in the direction of the y-axis is provided. 
     Thus, according to the optical semiconductor apparatus  10  of the second embodiment, effects of the optical semiconductor apparatus  10  according to the first embodiment can be achieved and more precise adjustment of the position of the lens  13  on the xy-plane with respect to the light emitted from the LD  12  can be realized by the fixing ring  41 . As a result, the light emitted from the LD  12  is coupled with the end of the optical fiber  18  with greater precision and coupling loss of the light output from the output unit  16  can be reduced. 
       FIG. 6  is a front cross-sectional view of the optical semiconductor apparatus according to a third embodiment. In  FIG. 6 , components identical to those depicted in  FIG. 4  are given identical reference numerals and description thereof is omitted. As depicted in  FIG. 6 , the optical semiconductor apparatus  10  according to the third embodiment has a configuration in which the portion of the Peltier element  15  depicted in  FIG. 4  and positioned at the lower aspect of the second support  14   b  and the intermediate portion  14   c  is omitted. 
     In other words, only the portion of the Peltier element  15  positioned at the lower aspect of the first support  14   a  is provided. As a result, the Peltier element  15  is provided in contact with the first support  14   a  and is separate from the second support  14   b.  Here, although a gap  61  between the second support  14   b  and the casing  11  is empty, thermal insulation may be provided in the gap  61 . 
     Since the lens  13 , the lens holder  13   a,  the second support  14   b,  and the fixing ring  41  are provided near the LD  12 , heat generated by the LD  12  causes the temperature of these components to rise. However, despite this fundamentally, temperature control for the lens  13 , the lens holder  13   a,  the second support  14   b,  and the fixing ring  41  is not required. Therefore, if the Peltier element  15  absorbs the heat of these components, the cooling function of the Peltier element  15  is wastefully expended. 
     With this being the case, by isolating the Peltier element  15  from the second support  14   b,  the heat of the lens  13 , the lens holder  13   a,  the second support  14   b,  and the fixing ring  41 , whose temperatures that have risen, is not directly transferred to the Peltier element  15 . Further, as the width of the intermediate portion  14   c  in the direction of the x-axis is relatively small compared to the second support  14   b,  thermal conductivity of the intermediate portion  14   c  is low. Thus, the heat transferred to the Peltier element  15  from the second support  14   b  through the intermediate portion  14   c  can be reduced. 
     Additionally, in the configuration depicted in  FIG. 4 , the portion of the Peltier element  15  positioned at the lower aspect of the intermediate portion  14   c  is omitted here. As a result, heat transferred to the intermediate portion  14   c  from the second support  14   b  is not directly transferred to the Peltier element  15 ; thereby enabling further reduction of the heat transferred to the Peltier element  15  from the second support  14   b  through the intermediate portion  14   c.    
     Thus, according to the optical semiconductor apparatus  10  of the third embodiment, effects of the optical semiconductor apparatus  10  according to the second embodiment can be achieved and wasteful use of the cooling function of the Peltier element  15  by cooling the lens  14 , the second support  14   b,  etc. can be prevented by isolating the Peltier element  15  from the second support  14   b.  As a result, the cooling effect of the Peltier element  15  with respect to the LD  12  is improved and power consumption of the Peltier element  15  can be reduced. 
       FIG. 7  is a front cross-sectional view of the optical semiconductor apparatus according to a fourth embodiment. In  FIG. 7 , components identical to those depicted in  FIG. 4  are given identical reference numerals and description thereof is omitted. As depicted in  FIG. 7 , the optical semiconductor apparatus  10  according to the fourth embodiment has a configuration similar to the configuration depicted in  FIG. 4 ; however, the configuration further includes thermal insulation  71  between the Peltier element  15  and the second support  14   b.    
     As a result, the Peltier element  15  is provided in contact with the first support  14   a  and is thermally isolated from the second support  14   b  by the thermal insulation  71 . Hence, the heat of the lens  13 , the lens holder  13   a,  the second support  14   b,  and the fixing ring  41 , whose temperatures have been raised by the heat generated by the LD  12 , is not directly transferred to the Peltier element  15 . Therefore, heat transferred to the Peltier element  15  from the second support  14   b  through the intermediate portion  14   c  can be reduced. 
     Additionally, here, the thermal insulation  71  is continuously formed from between the Peltier element  15  and 1) the second support  14   b  and 2) the intermediate portion  14   c.  As a result, the Peltier element  15  is also thermally isolated from the intermediate portion  14   c.  Thus, heat transferred to the intermediate portion  14   c  from the second support  14   b  is not directly transferred to the Peltier element  15  and the heat transferred to the Peltier element  15  from the second support  14   b  can be further reduced. 
     Thus, according to the optical semiconductor apparatus  10  of the fourth embodiment, effects of the optical semiconductor apparatus  10  according to the second embodiment can be achieved and wasteful use of the cooling function of the Peltier element  15  by cooling the lens  13  and other components can be prevented by thermally isolating the Peltier element  15  from the second support  14   b  by the thermal insulation  71 . As a result, the cooling effect of the Peltier element  15  with respect to the LD  12  is improved and power consumption of the Peltier element  15  can be reduced. 
     Additionally, unlike the configuration depicted in for example  FIG. 6 , the Peltier element  15  can be provided beneath the second support  14   b  and the intermediate portion  14   c.  As a result, the volume of the Peltier element  15  can be made sufficiently large. Thus, compared to the configuration depicted in for example  FIG. 6 , the cooling function of the Peltier element  15  can be improved. 
       FIG. 8  is a front cross-sectional view of the optical semiconductor apparatus according to a fifth embodiment.  FIG. 9  is a top view of the optical semiconductor element and the stem depicted in  FIG. 8 . In  FIGS. 8 and 9 , components identical to those depicted in  FIG. 4  are given identical reference numerals and description thereof is omitted. Additionally, although reference numerals are not depicted here, similar to the configuration depicted in  FIG. 4 , the stem  14  includes the first support  14   a,  the second support  14   b,  and the intermediate portion  14   c.    
     As depicted in  FIG. 8 , the optical semiconductor apparatus  10  according to the fifth embodiment has a configuration similar to the configuration depicted in  FIG. 4 ; however, the stem  14  further includes a first structural portion  81  and a second structural portion  82 . The first structural portion  81  is a part that includes the upper aspect  14 A depicted in  FIG. 4 . Further, a lower aspect of the first structural portion  81  is in contact with the Peltier element  15 . The second structural portion  82  includes the aspect  14 B depicted in  FIG. 4  and encompasses the first structural portion  81 . The thermal conductivity of the first structural portion  81  is higher than that of the second structural portion  82 . 
     By raising the thermal conductivity of the first structural portion  81 , the heat generated by the LD  12  is efficiently transferred to the Peltier element  15  via the first structural portion  81  and the cooling effect of the Peltier element  15  with respect to the LD  12  can be improved. Further, by setting a low thermal conductivity for the second structural portion  82 , the Peltier element  15  becomes thermally isolated from the lens  13 , the lens holder  13   a,  and the fixing ring  41  via the second support  14   b.    
     As a result, the heat of the lens  13 , the lens holder  13   a,  and the fixing ring  41 , whose temperatures have been raised by the heat generated by the LD  12 , is not directly transferred to the Peltier element  15 . Therefore, the heat transferred to the Peltier element  15  from the lens  13  and other components can be reduced and wasteful use of the cooling function of the Peltier element  15  by cooling the lens  13  and other components can be prevented. 
     Furthermore, by setting a low thermal conductivity for the second structural portion  82 , the fixing ring  41  can be easily fixed to the aspect  14 B by laser welding. Preferably, the coefficient of thermal expansion of the first structural portion  81  is substantially equivalent to that of the second structural portion  82 . Specifically, the coefficient of thermal expansion of the first structural portion  81  is preferably at least half and not more than twice that of the second structural portion. 
     For example, the first structural portion  81  is fabricated of kovar (coefficient of thermal expansion: 3.2×10 −6 /K) and the second structural portion  82  is fabricated of Pyrex glass (coefficient of thermal expansion: 4.8×10 −6 /K). Thus, even if the first structural portion  81  and the second structural portion  82  thermally expand from the heat generated by the LD  12 , the first structural portion  81  and the second structural portion  82  expand at a comparable rate and hence, deviation of the respective positions of the aspect  14 A supporting the LD  12  and the aspect  14 B supporting the lens  13  can be prevented. 
     For example, a through-hole of a shape corresponding to the first structural portion  81  is provided in the Pyrex glass forming the second structural portion  82  and kovar forming the first structural portion  81  is inserted in the through-hole provided. Thus, the Pyrex glass and the kovar are integrated to form the stem  14 . Further, after the kovar is inserted into the Pyrex glass, by removing any unevenness between the Pyrex glass and the kovar by polishing, etc., relative positions of the aspect  14 A supporting the LD  12  and the aspect  14 B supporting the lens  13  can be determined with great precision. 
     Thus, according to the optical semiconductor apparatus  10  of the fifth embodiment, effects of the optical semiconductor apparatus  10  according to the second embodiment can be achieved and by configuring the stem  14  of the first structural portion  81  having a high thermal conductivity and the second structural portion having a low thermal conductivity, the cooling effect of the Peltier element  15  with respect to the LD  12  is improved and power consumption of the Peltier element  15  can be reduced. Additionally, by setting a low thermal conductivity for the second structural portion  82 , the fixing ring  41  can be easily fixed to the aspect  14 B by laser welding. 
       FIG. 10  is a front cross-sectional view of the optical semiconductor apparatus according to a sixth embodiment.  FIG. 11  is a top view of the optical semiconductor element and the stem depicted in  FIG. 10 . In  FIG. 10 , components identical to those depicted in  FIG. 4  are given identical reference numerals and description thereof is omitted. The optical semiconductor apparatus  10  according to the sixth embodiment is an amplifying apparatus that amplifies and outputs light input thereto. 
     As depicted in  FIG. 10 , the optical semiconductor apparatus  10  has the configuration depicted in  FIG. 4  with the addition of an input unit  101 , a lens  106  (second lens), and a fixing ring  107 . Further, in place of the LD  12  depicted in  FIG. 4 , an SOA  108  is provided. The SOA  108  amplifies an optical signal input thereto from the lens  106  and outputs the optical signal to the lens  13 . An opening  105  for the input of light is provided in the casing  11 . 
     The input unit  101  is provided at the opening  105  on the external side of the casing  11 . The input unit  101  includes an optical fiber  102 , a lens  103 , and an isolator  104 . An optical signal from an external source is input to the optical fiber  102 . The optical fiber  102  outputs the optical signal input thereto to the lens  103 . The lens  103  collimates the optical signal output from the optical fiber  102  and outputs the collimated optical signal to the isolator  104 . 
     The isolator  104  transmits the optical signal output from the lens  103  to the lens  106 . In addition, the isolator  104  blocks light traveling from the lens  106  toward the lens  103 . The lens  106  converges the optical signal output from the isolator  104  and inputs the converged light to the SOA  108 . A lens holder  106   a  supporting the lens  106  is provided at the lens  106 . The lens  106  is fixed held by the lens holder  106   a.    
     The stem  14  is a support member supporting the SOA  108 , the lens  13 , and the lens  106 . The stem  14  includes the first support  14   a,  the second support  14   b,  the intermediate portion  14   c,  a third support  14   d,  and a second intermediate portion  14   e.  The third support  14   d  is provided on a side opposite of the second support  14   b  of the stem  14 . The first support  14   a  and the third support  14   d  are integrated via the second intermediate portion  14   e.    
     In other words, the first support  14   a,  the second support  14   b,  the intermediate portion  14   c,  the third support  14   d,  and the second intermediate portion  14   e  are integrated. The third support  14   d  supports the lens  106 . Specifically, the third support  14   d  has, at a position where light output from the isolator  104  is transmitted, a through-hole of a size corresponding to the lens  106  and into which the lens  106  is inserted to support the lens  106 . 
     The third support  14   d  has an aspect  14 D oriented perpendicular to the upper aspect  14 A of the first support  14   a  where the SOA  108  is placed. The fixing ring  107  is positioning member that holds the lens  106  and positions the lens  106  with respect to the third support  14   d.  The shape of the fixing ring  107  is identical to that of the fixing ring  41  (refer to  FIG. 5 ). The fixing ring  107  has an aspect  107 A that is fixed in contact with the aspect  14 D of the third support  14   d.    
     The lens  106  and the lens holder  106   a  are arranged in an opening of the fixing ring  107  and, are fixed and held by the fixing ring  107 . At the time of assembly of the optical semiconductor apparatus  10 , the aspect  107 A of the fixing ring  107  is not fixed to the aspect  14 D of the third support  14   d.  Thus, the fixing ring  107  is slidable in the direction of the xy-plane. In this state, the light from the optical fiber  102  is input, the SOA  108  is operated, and the light output from the optical fiber  19  is monitored while the fixing ring  107  is slid with respect to the third support  14   d.    
     The position of the fixing ring  107  with respect to the third support  14   d  is determined as the position where the monitored light has the greatest power. Thereafter, the aspect  107 A of the fixing ring  107  is fixed by, for example, laser welding to the aspect  14 D of the third support  14   d.  As a result, the lens  106  can be fixed to the third support  14   d  in a state where the position of light output from the lens  106  on the xy-plane is adjusted with high precision with respect to the input unit of the SOA  108 . 
     Thus, according to the optical semiconductor apparatus  10  of the sixth embodiment, effects of the optical semiconductor apparatus  10  according to the fourth embodiment can be achieved and through integration of the first support  14   a  and the third support  14   d,  relative positions of the first support  14   a  and the third support  14   d  can be adjusted with high precision through fabrication of the stem  14 . As a result, the light input from the optical fiber  102  can be input to the SOA  108  with high precision and the transmission characteristics of the light output from the SOA  108  can be improved. 
       FIG. 12  is a top view of a modified example of the optical semiconductor element depicted in  FIGS. 10 and 11 . As depicted in  FIG. 12 , the SOA  108  depicted in  FIGS. 10 and 11  may be substituted with an SOA array  1201  having plural SOAs. The SOAs of the SOA array  1201  are arrayed in the direction of the y-axis and are fixed to the stem  14  by the element carrier  12   a.    
     In this case, in place of the optical fiber  102  depicted in  FIG. 10 , an optical fiber array (not depicted) is provided having plural optical fibers arrayed in the direction of the y-axis. Each of the optical fibers of the optical fiber array is input with light from an external source. The lights respectively input to the optical fibers of the optical fiber array are input to the SOAs of the SOA array  1201 . 
     Additionally in this case, in place of the optical fiber  19  depicted in  FIG. 10 , an optical fiber array (not depicted) is provided having plural optical fibers arrayed in the direction of the y-axis. The lights output from the SOA array  1201  are respectively coupled to the ends of the optical fibers of the optical fiber array and are output to an external destination by the optical fibers. 
     According to the optical semiconductor apparatus  10 , the coupling position of the lights output from the SOA array  1201  can be adjusted with precision in the direction of the x-axis. Therefore, respective coupling positions of lights output from the SOA array  1201  are easily aligned in a straight line along the direction of the y-axis. As a result, with precision, each of the lights output can be coupled with the ends of the optical fibers of the optical fiber array aligned along the direction of the y-axis. Thus, the respective transmission characteristics of the channels of the optical fiber array can be improved. 
       FIG. 13  is a front cross-sectional view of the optical semiconductor apparatus according to a seventh embodiment.  FIG. 14  is a front view and a side view of an optical semiconductor element and a stem depicted in  FIG. 13 . In  FIG. 13 , components identical to those depicted in  FIG. 8  or  FIG. 10  are given identical reference numerals and description thereof is omitted. Further, the stem  14  includes the first support  14   a,  the second support  14   b,  the intermediate portion  14   c,  the third support  14   d,  and the second intermediate portion  14   e  although reference numerals thereof are not depicted. 
     As depicted in  FIGS. 13 and 14 , the optical semiconductor apparatus  10  according to the seventh embodiment has a configuration similar to the configuration depicted in  FIG. 10 ; however, the stem  14  further includes the first structural portion  81  and the second structural portion  82 . Here, the second structural portion  82  includes both the aspect  14 B and the aspect  14 D depicted in  FIG. 10 , and encompasses the first structural portion  81 . As descriptions of the first structural portion  81  and the second structural portion  82  are identical to the descriptions given with respect to  FIGS. 8 and 9 , description herein is omitted. 
     Here, in place of the SOA  108  depicted in  FIG. 10 , the SOA array  1201  (refer to  FIG. 12 ) is provided. Further, in place of the optical fiber  102  depicted in  FIG. 10 , an optical array  1301  is provided having plural optical fibers arrayed in the direction of the y-axis. Light from an external source is input to each of the optical fibers of the optical fiber array  1301 . The light input from the optical fibers is input to each of the SOAs of the SOA array  1201 . 
     Further, in this case, in place of the optical fiber  19  depicted in  FIG. 10 , an optical fiber array  1302  is provided having plural optical fibers arrayed in the direction of the y-axis. The lights output from the SOA array  1201  are coupled respectively with the ends of the optical fibers of the optical fiber array  1302  and are output to an external destination by the optical fibers. 
     Thus, according to the optical semiconductor apparatus  10  of the seventh embodiment, effects of the optical semiconductor apparatus  10  according to the sixth embodiment can be achieved and by configuring the stem  14  of the first structural portion  81  having a high thermal conductivity and the second structural portion having a low thermal conductivity, the cooling effect of the Peltier element  15  with respect to the SOA array  1201  is improved and power consumption of the Peltier element  15  can be reduced. Additionally, by setting a low thermal conductivity for the second structural portion  82 , the fixing ring  41  can be easily fixed to the aspect  14 B by laser welding. Additionally, the fixing ring  107  can be easily fixed to the aspect  14 D by laser welding. 
     As set forth above, according to the configuration above, through integration of the first support and the second support, respective positions of the first support supporting the optical semiconductor element and the second support supporting the lens can be adjusted with high precision by fabricating a member that determines the relative positions. 
     As described above, according to the optical semiconductor apparatus disclosed, transmission characteristics of output light can be improved. 
     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.