Patent Publication Number: US-2012033695-A1

Title: Semiconductor laser apparatus and optical apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The priority application number JP2010-175698, Semiconductor Laser Apparatus and Optical Apparatus, Aug. 4, 2010, Nobuhiko Hayashi et al., upon which this patent application is based is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor laser apparatus and an optical apparatus, and more particularly, it relates to a semiconductor laser apparatus comprising a package sealing a semiconductor laser chip and an optical apparatus employing the same. 
     2. Description of the Background Art 
     A semiconductor laser device has been widely applied as a light source for an optical disc system, an optical communication system or the like in general. For example, an infrared semiconductor laser device emitting a laser beam having a wavelength of about 780 nm has been put into practice as a light source for reading of a CD, and a red semiconductor laser device emitting a laser beam having a wavelength of about 650 nm has been put into practice as a light source for writing/reading of a DVD. A blue-violet semiconductor laser device emitting a laser beam having a wavelength of about 405 nm has been put into practice as a light source for a Btu-ray disc. 
     In order to attain such a light source apparatus, a semiconductor laser apparatus comprising a package sealing a semiconductor laser chip is known in general, as disclosed in each of Japanese Patent Laying-Open Nos. 9-205251 (1997), 10-209551 (1998) and 2009-135347, for example. 
     Japanese Patent Laying-Open No. 9-205251 (1997) discloses a plastic-molded apparatus of a semiconductor laser comprising a header formed with a flange surface and made of a resin product, a semiconductor laser chip mounted on the header and a transparent cap of resin covering the periphery of the semiconductor laser chip. In this plastic-molded apparatus, an edge of an opening of the transparent cap is bonded onto the flange surface of the header through an adhesive containing an epoxy resin-based material, whereby the semiconductor laser chip is hermetically sealed. 
     Japanese Patent Laying-Open No. 10-209551 (1998) discloses a semiconductor laser apparatus comprising a header made of a resin product, a semiconductor laser chip mounted on a chip set portion of the header and a transparent cap (lid member) of resin having an L-shaped cross section. In this semiconductor laser apparatus, an outer edge of the transparent cap is bonded to the chip set portion of the header through a photosetting adhesive or the like, whereby the semiconductor laser chip is hermetically sealed. 
     Japanese Patent Laying-Open No. 2009-135347 discloses an optical module comprising a substrate made of a metal material, a surface-emitting laser chip mounted on an upper surface of the substrate and a package member (sealing member) sealing space in the periphery of a laser beam source. The package member of this optical module is made of a resin material other than a metal material. For example, an ethylene-polyvinyl alcohol copolymer (EVOH resin) is shown as an example of this resin material. 
     However, in the semiconductor apparatus disclosed in each of Japanese Patent Laying-Open Nos. 9-205251 (1997) and 10-209551 (1998), the epoxy resin-based adhesive, or the photosetting adhesive or the like is employed to bond the header and the transparent cap to each other. If these adhesives contain many volatile gas components such as organic gas especially before being hardened, a package may be filled with the aforementioned volatile gas after bonding. Further, the header and the transparent cap are made of a resin material, and hence low molecular siloxane, volatile organic gas or the like existing outside the semiconductor apparatus (in the atmosphere) may penetrate into the resin material and enter the package. In this case, an adherent substance is easily formed on a laser emitting facet of the semiconductor laser chip by exciting and decomposing the low molecular siloxane or the volatile gas by a high-energy laser beam having a short lasing wavelength especially if a blue-violet semiconductor laser chip is sealed. In this case, the adherent substance absorbs the laser beam, and hence the temperature of the laser emitting facet is easily increased. Consequently, the semiconductor laser chip is disadvantageously deteriorated. 
     In the optical module (semiconductor apparatus) disclosed in Japanese Patent Laying-Open No. 2009-135347, low molecular siloxane, volatile organic gas or the like existing outside the optical module (in the atmosphere) may penetrate into a resin material and enter the package member if the package member is made of the resin material. At this time, as to the EVOH resin having a thickness increased to such an extent as to form the package member, cracks are easily generated in members due to an impact from outside or the like. In this case, the low molecular siloxane, the volatile organic gas or the like existing outside may penetrate into clearances of the cracks and enter the package member. In this case, an adherent substance formed on a laser emitting facet absorbs a laser beam, and hence the temperature of the laser emitting facet is easily increased. Consequently, the semiconductor laser chip is disadvantageously deteriorated. 
     SUMMARY OF THE INVENTION 
     A semiconductor laser apparatus according to a first aspect of the present invention comprises a package constituted by a plurality of members, having sealed space inside, and a semiconductor laser chip arranged in the sealed space, wherein surfaces of the members located in the sealed space are covered with a covering agent made of an ethylene-polyvinyl alcohol copolymer. 
     In the semiconductor laser apparatus according to the first aspect of the present invention, as hereinabove described, the surfaces of the members constituting the package located in the sealed space are covered with the covering agent made of the ethylene-polyvinyl alcohol copolymer (EVOH). The EVOH is a resin material having excellent gas barrier properties, and hence the covering agent covering the aforementioned members can block volatile organic gas from penetrating into the sealed space of the package even if the volatile organic gas is generated from the members located in the sealed space of the package. Further, even if low molecular siloxane, volatile organic gas or the like existing outside the semiconductor laser apparatus (in the atmosphere) penetrates into the components of the package, the covering agent covering the aforementioned members can inhibit the low molecular siloxane, the volatile organic gas or the like from entering the package. Further, the EVOH hardly generates the aforementioned volatile component, and hence the semiconductor laser chip in the package is not exposed to the organic gas or the like. Consequently, an adherent substance can be inhibited from being formed on a laser emitting facet, and hence the semiconductor laser chip can be inhibited from deterioration. The inventors have found as a result of a deep study that the EVOH is employed as the covering agent in the present invention. 
     In the aforementioned semiconductor laser apparatus according to the first aspect, the package preferably includes a resin member containing a volatile component, and a surface of the resin member located in the sealed space is preferably covered with the covering agent. According to this structure, the covering agent can effectively block volatile organic gas in the resin member from penetrating into the sealed space of the package. Further, the resin member can be employed in the package, and hence a manufacturing process can be simplified as compared with a case where the package is made of a conventional metal material. Thus, the manufacturing process is simplified, and hence the semiconductor laser apparatus can be inexpensively manufactured. 
     The aforementioned semiconductor laser apparatus according to the first aspect preferably further comprises a metal plate for mounting the semiconductor laser chip on an inner bottom surface of the package, wherein a surface of the metal plate other than a region on which the semiconductor laser chip is placed is covered with the covering agent. According to this structure, contaminations attached to the surface of the metal plate other than the region on which the semiconductor laser chip is placed in the manufacturing process can also be covered with the covering agent. Thus, the inside of the sealed space of the package can be kept cleaner. 
     In the aforementioned structure further comprising the metal plate on the inner bottom surface of the package, the package preferably includes a resin member containing a volatile component, and a surface of the resin member located in the sealed space and the surface of the metal plate other than the region on which the semiconductor laser chip is placed are preferably continuously covered with the covering agent. According to this structure, the surfaces of the members constituting the package located in the sealed space are reliably covered with the covering agent with no clearance, and hence the covering agent can reliably block the volatile organic gas from penetrating into the sealed space of the package. 
     In the aforementioned structure in which the package includes the resin member containing the volatile component, the package preferably includes a base made of resin, mounted with the semiconductor laser chip, and a surface of the base located in the sealed space is preferably covered with the covering agent. According to this structure, the covering agent can effectively block volatile organic gas contained in the base from penetrating into the sealed space of the package. Further, the base can be made of resin, and hence the semiconductor laser apparatus can be inexpensively manufactured. 
     In the aforementioned structure in which the package includes the base made of resin, the base is preferably made of one of polyamide resin, epoxy resin, polyphenylene sulfide resin, a liquid crystal polymer and photosensitive resin. Even if the base is made of one of the aforementioned resin materials, the covering agent can effectively block the volatile organic gas contained in the base from penetrating into the sealed space of the package. Further, the manufacturing process can be simplified by making the base of one of the aforementioned resin materials as compared with a case where the package is made of a conventional metal material. 
     The aforementioned semiconductor laser apparatus according to the first aspect preferably further comprises a photodetector arranged in the sealed space, monitoring an intensity of a laser beam from the semiconductor laser chip, wherein the photodetector is fixed through a conductive adhesive layer containing a volatile component in the sealed space, and a surface of the conductive adhesive layer fixing the photodetector exposed in the sealed space is covered with the covering agent. According to this structure, the covering agent can block volatile organic gas from penetrating into the sealed space of the package even if the volatile organic gas is generated from the conductive adhesive layer. Consequently, formation of an adherent substance on a photodetecting surface of the photodetector in addition to the laser emitting facet can be inhibited, and hence output of a laser beam from the semiconductor laser chip can be accurately controlled with this photodetector. 
     In the aforementioned semiconductor laser apparatus according to the first aspect, the package preferably includes a base mounted with the semiconductor laser chip and a sealing member mounted on the base, and at least a surface of the sealing member located in the sealed space is preferably covered with the covering agent. According to this structure, contaminants or the like attached to the surface of the sealing member on a side of the sealed space are covered with the covering agent, and hence the sealed space of the package can be inhibited from being filled with organic gas generated from these contaminants, and the contaminants can be inhibited from being detached from the surface of the sealing member to fill the sealed space. Further, the strength (rigidity) of the sealing member can be improved by the covering agent provided on the surface (one surface) of the sealing member. Consequently, the sealing member having a prescribed magnitude of rigidity can be easily made even if a low-cost member is employed. 
     In the aforementioned structure in which the package includes the base and the sealing member, a substantially entire surface of the sealing member on a side bonded to the base including the surface of the sealing member located in the sealed space is preferably covered with the covering agent. According to this structure, the covering agent can be easily formed on one surface (inner surface) of the sealing member in the manufacturing process. Further, the surface of the sealing member located in the sealed space can be reliably covered with the covering agent regardless of a bonding position (mounting method) of the sealing member to the base. 
     In the aforementioned structure in which the substantially entire surface of the sealing member on the side bonded to the base is covered with the covering agent, the covering agent is preferably arranged on a bonded region of the sealing member and the base. According to this structure, the covering agent is arranged on not only the surfaces located in the sealed space of the package but also the bonded region of the sealing member and the base, and hence the low molecular siloxane, the volatile organic gas or the like existing outside the semiconductor laser apparatus (in the atmosphere) can be effectively inhibited from entering the sealed space of the package through the bonded region of the sealing member and the base. 
     In this case, the sealing member is preferably bonded to the base with the covering agent arranged on the bonded region of the sealing member and the base. According to this structure, the covering agent can also serve as a bonding member of the sealing member and the base. Further, the EVOH (covering agent) hardly generating the volatile component and having excellent gas barrier properties is employed, dissimilarly to a case where the sealing member and the base are bonded to each other with a general adhesive containing the volatile component, and hence the sealed space of the package can be effectively inhibited from being filled with volatile organic gas. 
     In the aforementioned structure in which the substantially entire surface of the sealing member on the side bonded to the base is covered with the covering agent, the sealing member is preferably made of metal foil, and substantially entire inner surface of the sealing member made of the metal foil having a side cross section bent in a substantially L-shaped manner from an upper surface to a front surface of the base is preferably covered with the covering agent. According to this structure, the strength (rigidity) of the sealing member can be easily improved by the covering agent provided along the inner surface of the sealing member even if the sealing member is formed by bending the metal foil in a substantially L-shaped manner. 
     In the aforementioned structure in which the package includes the base and the sealing member, the base preferably has a recess portion provided with an opening from an upper surface to a front surface, and an inner surface of the recess portion and an inner surface of the sealing member are preferably continuously covered with the covering agent. According to this structure, the surfaces of the members constituting the package located in the sealed space are reliably covered with covering agent with no clearance, and hence the covering agent can reliably block volatile organic gas generated outside the package or from the base from penetrating into the sealed space of the package. In the present invention, the “front surface” denotes a side surface on a side where the laser beam emitted from the semiconductor laser chip is emitted outward. 
     In the aforementioned structure in which the package includes the base and the sealing member, the sealing member is preferably made of elastic resin, the package is preferably sealed by fitting the base and the sealing member into each other, and surfaces of the base and the sealing member exposed in the sealed space are preferably covered with the covering agent. According to this structure, the base and the sealing member can be easily brought into close contact with each other, and hence the package can be easily sealed. In other words, it is not necessary to employ an additional adhesive or the like for sealing, and hence generation of organic gas can be inhibited. 
     In this case, the sealing member is preferably cylindrically formed with a bottom portion, a cylindrical inner peripheral surface of the sealing member is preferably circularly fitted into an outer peripheral surface of the base, and the covering agent is preferably arranged on a region in which the base and the sealing member are circularly fitted into each other in addition to the surfaces of the base and the sealing member exposed in the sealed space. According to this structure, the covering agent is arranged on not only the surfaces located in the sealed space of the package but also the bonded region of the sealing member and the base, and hence the low molecular siloxane, the volatile organic gas or the like existing outside the semiconductor laser apparatus (in the atmosphere) can be reliably inhibited from entering the sealed space of the package through the bonded region of the sealing member and the base. 
     In the aforementioned semiconductor laser apparatus according to the first aspect, the package preferably includes a sealing member mounted on the base and a window member transmitting a laser beam emitted from the semiconductor laser chip to an outside of the package, and the window member is preferably bonded to the sealing member with the covering agent arranged on a surface of the sealing member other than an opening formed in the sealing member. According to this structure, the package can be easily sealed with the window member for emitting the laser beam without harmful effects such as contact of the laser beam with the covering agent. 
     In the aforementioned semiconductor laser apparatus according to the first aspect, a gas absorbent is preferably set in the sealed space of the package. According to this structure, even if the low molecular siloxane, the volatile organic gas or the like existing outside the semiconductor laser apparatus (in the atmosphere) penetrates into the sealed space, it can be easily absorbed by the gas absorbent. Thus, a concentration of organic gas or the like in the sealed space of the package can be reduced. 
     In this case, the gas absorbent is preferably sandwiched in contact with the covering agent in the sealed space to be fixed. According to this structure, the gas absorbent set in the sealed space can be prevented from easily moving in the sealed space, and hence contact of the laser beam from the semiconductor laser chip with the gas absorbent can be easily prevented. 
     In the aforementioned semiconductor laser apparatus according to the first aspect, the semiconductor laser chip preferably includes a nitride-based semiconductor laser chip. In the nitride-based semiconductor laser chip having a short lasing wavelength and requiring a higher output power, an adherent substance is easily formed on a laser emitting facet thereof, and hence the use of the aforementioned “covering agent” in the present invention is highly effective in inhibiting deterioration of the nitride-based semiconductor laser chip. 
     An optical apparatus according to a second aspect of the present invention comprises a semiconductor laser apparatus including a package constituted by a plurality of members, having sealed space inside and a semiconductor laser chip arranged in the sealed space, and an optical system controlling a beam emitted from the semiconductor laser apparatus, wherein surfaces of the members located in the sealed space are covered with a covering agent made of EVOH. 
     In the optical apparatus according to the second aspect of the present invention, the semiconductor laser apparatus is formed as described above, and hence the optical apparatus mounted with the semiconductor laser apparatus in which the semiconductor laser chip is inhibited from deterioration can be obtained. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a semiconductor laser apparatus according to a first embodiment of the present invention in which a base and a sealing member are separated from each other; 
         FIG. 2  is a longitudinal sectional view taken along the center line of the semiconductor laser apparatus according to the first embodiment of the present invention in a width direction; 
         FIGS. 3 and 4  are top plan views for illustrating a manufacturing process of the semiconductor laser apparatus according to the first embodiment of the present invention; 
         FIGS. 5 to 7  are perspective views for illustrating the manufacturing process of the semiconductor laser apparatus according to the first embodiment of the present invention; 
         FIG. 8  is a longitudinal sectional view taken along the center line of a semiconductor laser apparatus according to a modification of the first embodiment of the present invention in a width direction; 
         FIG. 9  is an exploded perspective view of a semiconductor laser apparatus according to a second embodiment of the present invention in which a base and a sealing member are separated from each other; 
         FIG. 10  is a longitudinal sectional view taken along the center line of the semiconductor laser apparatus according to the second embodiment of the present invention in a width direction; 
         FIG. 11  is an exploded perspective view of a semiconductor laser apparatus according to a third embodiment of the present invention in which a base and a cap are separated from each other; 
         FIG. 12  is a longitudinal sectional view taken along the center line of the semiconductor laser apparatus according to the third embodiment of the present invention in a width direction; 
         FIG. 13  is a longitudinal sectional view taken along the center line of a semiconductor laser apparatus according to a modification of the third embodiment of the present invention in a width direction; 
         FIG. 14  is an exploded perspective view of a semiconductor laser apparatus according to a fourth embodiment of the present invention in which a cap and a base are separated from each other; 
         FIG. 15  is a longitudinal sectional view taken along the center line of the semiconductor laser apparatus according to the fourth embodiment of the present invention in a width direction; 
         FIGS. 16 and 17  are sectional views for illustrating a manufacturing process of a cap of the semiconductor laser apparatus according to the fourth embodiment of the present invention; 
         FIG. 18  is a sectional view for illustrating a manufacturing process of a cap of a semiconductor laser apparatus according to a modification of the fourth embodiment of the present invention; 
         FIG. 19  is a longitudinal sectional view showing a structure of a semiconductor laser apparatus according to a fifth embodiment of the present invention; 
         FIG. 20  is a top plan view showing the structure of the semiconductor laser apparatus according to the fifth embodiment of the present invention; 
         FIGS. 21 to 23  are sectional views for illustrating a manufacturing process of the semiconductor laser apparatus according to the fifth embodiment of the present invention; 
         FIG. 24  is a top plan view of a three-wavelength semiconductor laser apparatus according to a sixth embodiment of the present invention, from which a sealing member is removed; and 
         FIG. 25  is a schematic diagram showing a structure of an optical pickup comprising the three-wavelength semiconductor laser apparatus according to the eighth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the present invention are hereinafter described with reference to the drawings. 
     First Embodiment 
     A structure of a semiconductor laser apparatus  100  according to a first embodiment of the present invention is now described with reference to  FIGS. 1 and 2 . 
     The semiconductor laser apparatus  100  according to the first embodiment of the present invention comprises a blue-violet semiconductor laser chip  20  having a lasing wavelength of about 405 nm and a package  90  sealing the blue-violet semiconductor laser chip  20 . The package  90  has a base  10  mounted with the blue-violet semiconductor laser chip  20  and a sealing member  30  mounted on the base  10 , covering the blue-violet semiconductor laser chip  20  from two directions, that is, from upper (a C 2  side) and front (an A 1  side) sides. The blue-violet semiconductor laser chip  20  is an example of the “semiconductor laser chip” in the present invention. 
     The base  10  has a tabular base body  10   a  with a thickness t 1  (in a direction C) made of polyamide resin, as shown in  FIG. 1 . A recess portion  10   b  recessed by a depth about half the thickness t 1  downward (to a C 1  side) is formed in about half a front region of the base body  10   a . A front wall portion  10   c  of the base body  10   a  on the front side is provided with a substantially rectangular opening  10   d  having a width W 3  on the central portion in a width direction (direction B). Therefore, the recess portion  10   b  is arranged with a substantially rectangular opening  10   e , which opens in an upper surface  10   i , and the opening  10   d , which opens on the front side. The recess portion  10   b  is constituted by the front wall portion  10   c , a pair of side wall portions  10   f  extending substantially parallel to each other backward (to an A 2  side) from both side ends of the front wall portion  10   c , an inner wall portion  10   g  connecting back ends (on the A 2  side) of the side wall portions  10   f  and a bottom surface connecting the front wall portion  10   c , the pair of side wall portions  10   f  and the inner wall portion  10   g  on the lower portion. 
     In the base  10 , lead frames  11 ,  12  and  13  made of metal are so arranged as to pass through the base body  10   a  from the front side to the back side in a state of being isolated from each other. In plan view, the lead frame  11  passes through a substantially central portion of the base body  10   a  in the direction B while the lead frames  12  and  13  are arranged on the outer sides (a B 2  side and a B 1  side) of the lead frame  11  in the width direction. Back end regions of the lead frames  11 ,  12  and  13 , extending backward are exposed from a back wall portion  10   h  of the base body  10   a  at the back. The lead frame  11  is an example of the “metal plate” in the present invention. 
     Front end regions  11   a ,  12   a  and  13   a  of the lead frames  11 ,  12  and  13  at the front are exposed from the inner wall portion  10   g  of the base body  10   a , and the front end regions  11   a  to  13   a  are arranged on the bottom surface of the recess portion  10   b . The front end region  11   a  of the lead frame  11  widens in the direction B on the bottom surface of the recess portion  10   b . The bottom surface of the recess portion  10   b  is an example of the “inner bottom surface of the package” in the present invention. 
     The lead frame  11  is integrally formed with a pair of heat radiation portions  11   d  connected to the front end region  11   a . The pair of heat radiation portions  11   d  are arranged substantially symmetrically about the lead frame  11  on both sides in the direction B. The heat radiation portions  11   d  extend from the front end region  11   a  and pass through side surfaces of the base body  10   a  in directions B 1  and B 2  to be exposed. Therefore, heat generated by the operating blue-violet semiconductor laser chip  20  is transferred to a submount  40  and the heat radiation portions  11   d  on both sides to be radiated to the outside of the semiconductor laser apparatus  100 . 
     The sealing member  30  is made of aluminum foil. The sealing member  30  has a ceiling surface portion  30   a  with a thickness t 2  of about 50 μm and a width W 1  (in the direction B) and a front surface portion  30   b  with a thickness t 2  and a width W 2  (W 2  W 1 ) bent at an end of the ceiling surface portion  30   a  on one side (A 1  side) and extending downward, as shown in  FIG. 1 . The ceiling surface portion  30   a  and the front surface portion  30   b  are formed in a state of being substantially orthogonal to each other, whereby a side cross section of the sealing member  30  in a direction A is substantially L-shaped. The width W 2  of the front surface portion  30   b  is larger than an opening length W 3  of the opening  10   d  in the direction B (W 2 &gt;W 3 ). 
     As shown in  FIG. 2 , a sealant  15  with a thickness t 3  of about 0.2 mm is applied to a substantially entire region on an inner surface  30   c  becoming a back surface of the sealing member  30 . Eval (registered trademark, Eval F104B manufactured by Kuraray Co., Ltd.) which is EVOH resin is employed as the sealant  15 . The EVOH resin is a material having excellent gas barrier properties and mainly applied to a food wrapper and so on as a multilayered film. 
     A hole  34  (window portion) penetrating through the sealing member  30  in a thickness direction is provided in a substantially central portion of the front surface portion  30   b . A light transmission portion  35  having translucence, made of borosilicate glass with a thickness of about 0.25 mm is provided to cover the hole  34  from the outside (A 1  side) of the front surface portion  30   b . The light transmission portion  35  is bonded onto the front surface portion  30   b  through the sealant  15  with a thickness of about 0.1 mm applied onto an outer surface of the front surface portion  30   b  other than the hole  34 . Therefore, the hole  34  is completely closed by the light transmission portion  35  mounted through the sealant  15 . A covering agent  16  is not applied onto the light transmission portion  35 , and dielectric films  31  of Al 2 O 3  are formed on surfaces of the light transmission portion  35  on the A 1  and A 2  sides. The hole  34  is an example of the “opening” in the present invention. The light transmission portion  35  is an example of the “window member” in the present invention. 
     In this state, the sealing member  30  and the base  10  are bonded to each other through the sealant  15 . In other words, the sealing member  30  is mounted on the base  10  through the sealant  15  in the periphery (a region near the inner wall portion  10   g  and respective upper surfaces of the pair of side wall portions  10   f  and the front wall portion  10   c ) of the opening  10   e  in the upper surface  10   i  and the periphery of the opening  10   d  in the front surface (an outer surface (on the A 1  side) of the front wall portion  10   c ). In other words, the sealing member  30  is bonded to the base  10  with the sealant  15  also serving as the “covering agent” in the present invention arranged on a bonded region of the sealing member  30  and the base  10 . The aforementioned bonded region with the sealant  15  is annularly formed to have continuity. Thus, the openings  10   d  and  10   e  are completely closed by the sealing member  30 , and the blue-violet semiconductor laser chip  20  is sealed with the package  90 . Therefore, in the semiconductor laser apparatus  100 , an adherent substance or the like caused by a volatile component is not generated or hardly generated on a light-emitting surface in the package  90 . 
     The blue-violet semiconductor laser chip  20  is mounted on a substantially central portion of an upper surface of the front end region  11   a  of the lead frame  11  through the submount  40  having conductivity. 
     The blue-violet semiconductor laser chip  20  is mounted in a junction-up system such that the light-emitting surface faces forward. In a pair of cavity facets formed on the blue-violet semiconductor laser chip  20 , that emitting a laser beam having relatively large light intensity serves as the light-emitting surface and that having relatively small light intensity serves as a light-reflecting surface. The blue-violet semiconductor laser chip  20  emits the laser beam in a direction A 1 . A dielectric multilayer film (not shown) made of an AlN film, an Al 2 O 3  film or the like is formed on the light-emitting surface and the light-reflecting surface of the blue-violet semiconductor laser chip  20  by facet coating treatment in a manufacturing process. 
     A first end of a metal wire  91  made of Au or the like is bonded to a p-side electrode  21  formed on an upper surface of the blue-violet semiconductor laser chip  20 , and a second end of the metal wire  91  is connected to the front end region  12   a . An n-side electrode  22  formed on a lower surface of the blue-violet semiconductor laser chip  20  is electrically connected to the front end region  11   a  through the submount  40 . 
     A photodiode (PD)  42  employed to monitor an intensity of a laser beam is arranged on a side of the light-reflecting surface of the blue-violet semiconductor laser chip  20  in a back portion of the submount  40  such that a photodetecting surface faces upward. A lower surface (n-type region) of the tabular PD  42  is electrically connected to the front end region  11   a  through a conductive adhesive layer  5  made of resin paste (Ag paste or the like) containing a volatile component. A first end of a metal wire  92  made of Au or the like is bonded to an upper surface (p-type region) of the PD  42 , and a second end of the metal wire  92  is connected to the front end region  13   a . The photodiode (PD)  42  is an example of the “photodetector” in the present invention. 
     As shown in  FIGS. 1 and 2 , a covering agent  16  made of EVOH resin is applied with a prescribed thickness onto a surface of each member located in sealed space (closed space surrounded by the base  10  and the sealing member  30 ) of the package  90 . Specifically, the covering agent  16  continuously covers an inner surface (inner surfaces of the front wall portion  10   c , the pair of side wall portions  10   f  and the inner wall portion  10   g  and a bottom surface of the recess portion  10   b ) of the recess portion  10   b , a surface of the front end region  11   a  other than portions onto which the submount  40  and the PD  42  are bonded and surfaces of the front end regions  12   a  and  13   a  with no clearance. At this time, a surface of the conductive adhesive layer  5  protruding from a lower portion of the PD  42  is also covered with the covering agent  16 . The sealant  15  exposed in the sealed space of the package  90  of the sealant  15  applied onto the inner surface  30   c  also serves as the “covering agent” in the present invention. Therefore, the base body  10   a  of resin, the lead frames  11  to  13  and the inner surface  30   c  of the sealing member  30  located in the sealed space of the package  90  are completely covered with the “covering agent” in the present invention. 
     As shown in  FIG. 1 , a gas absorbent  49  made of silica gel is provided on the front end region  11   a  on a side (B 1  side) of the submount  40  in the package  90  through the covering agent  16 . The gas absorbent  49  is formed substantially in the form of a hemisphere having a bottom surface underneath, and a height from the bottom surface to a top of a spherical surface is slightly smaller than the depth (t 1 / 2 ) of the recess portion  10   b . Thus, the gas absorbent  49  is fixed in the recess portion  10   b  in a state of being sandwiched between the front end region  11   a  and the sealant  15  on the back surface (inner surface  30   c ) of the sealing member  30  and adhering thereto, as described later. The semiconductor laser apparatus  100  is constituted in the aforementioned manner. 
     A manufacturing process of the semiconductor laser apparatus  100  according to the first embodiment is now described with reference to  FIGS. 1 to 7 . 
     As shown in  FIG. 3 , a metal plate made of a strip-shaped thin plate of iron, copper or the like is first etched, thereby forming a lead frame  104  in which the lead frame  11  having the heat radiation portions  11   d  formed integrally with the front end region  11   a  and the lead frames  12  and  13  arranged on both sides of the lead frame  11  are repeatedly patterned laterally (in the direction B). At this time, the lead frames  12  and  13  are patterned in a state of being coupled by coupling portions  101  and  102  extending laterally. The heat radiation portions  11   d  are patterned in a state of being coupled by a coupling portion  103  extending laterally. 
     Thereafter, the base  10  (see  FIG. 1 ) having the base body  10   a  through which a set of the lead frames  11  to  13  passes and the recess portion  10   b  with the bottom surface on which the front end regions  11   a  to  13   a  of the respective frames are exposed is molded into the lead frame  104  by a resin molding apparatus, as shown in  FIG. 4 . At this time, the base body  10   a  is so molded that the front end regions  11   a  to  13   a  of the lead frames  11  to  13  are arranged in the recess portion  10   b.    
     The blue-violet semiconductor laser chip  20 , the PD  42  and the submount  40  are prepared through prescribed manufacturing processes. Then, the blue-violet semiconductor laser chip  20  is bonded onto one surface (upper surface) of the submount  40  with a conductive adhesive layer (not shown). At this time, the n-side electrode  22  is bonded onto the upper surface of the submount  40 . 
     Thereafter, the submount  40  is bonded onto the substantially central portion (in a lateral direction) of the upper surface of the front end region  11   a  through a conductive adhesive layer (not shown), as shown in  FIG. 4 . At this time, a lower surface of the submount  40  to which the blue-violet semiconductor laser chip  20  is not bonded is bonded onto the upper surface of the front end region  11   a . Then, the lower surface of the PD  42  is bonded onto a region at the rear of the submount  40  and between the front end region  11   a  and the inner wall portion  10   g  with the conductive adhesive layer  5 . At this time, the n-type region of the PD  42  is bonded to the lead frame  11 . 
     Thereafter, the p-side electrode  21  and the front end region  12   a  are connected with each other through the metal wire  91 , as shown in  FIG. 1 . The p-type region (upper surface) of the PD  42  and the front end region  13   a  are connected with each other through the metal wire  92 . 
     Then, the covering agent  16  is applied to continuously cover the inner surface (the inner surfaces of the front wall portion  10   c , the pair of side wall portions  10   f  and the inner wall portion  10   g  and the bottom surface of the recess portion  10   b ) of the recess portion  10   b , the surface of the front end region  11   a  other than the portions onto which the submount  40  and the PD  42  are bonded and the surfaces of the front end regions  12   a  and  13   a  in a state where the base  10  is heated to about 230° C. Thus, the covering agent  16  is also applied to the vicinities of the ends of the metal wires  91  and  92  on sides of the lead frames. 
     After cooling the base  10 , the lead frame  104  is cut along division lines  180  and  190 , as shown in  FIG. 4 , thereby cutting and removing the coupling portions  101 ,  102  and  103 . Thereafter, the gas absorbent  49  is placed on the front end region  11   a  on the side (B 1  side) of the submount  40 . At this time, the gas absorbent  49  is placed with the flat bottom surface down in a state where the top of the spherical surface is slightly smaller than the opening  10   e  (upper surface  10   i ). 
     Meanwhile, as shown in  FIG. 5 , the sealant  15  is applied with a thickness of about 0.2 mm onto an entire back surface  130   b  in a state where a sheet-like aluminum foil  130  having a thickness of about 17 μm is heated to about 220° C. Thereafter, a plurality of the holes  34  are formed in prescribed regions of the aluminum foil  130  at prescribed intervals. 
     Thereafter, the sealant  15  is annularly applied to the periphery of the hole  34  on an upper surface  130   a  of the aluminum foil  130  heated to about 220° C., as shown in  FIG. 6 . In a state where the sealant  15  is melted by heat, the light transmission portion  35  formed in a substantially disc shape and formed with the dielectric films  31  is press-bonded to close the hole  34 . Thereafter, the aluminum foil  130  is cooled thereby bonding the light transmission portion  35  onto the aluminum foil  130  through the sealant  15 . The sealant  15  applied onto the back surface  130   b  is also hardened by cooling, and hence a prescribed magnitude of rigidity is produced in the plate-like sealing member  30 . Then, the aluminum foil  130  is cut in a shape of the sealing member  30  developed on a plane surface, as shown in  FIG. 7 . 
     Thereafter, the unbent sealing member  30  is thermocompression bonded onto an upper surface of the base  10  in a state where the base  10  is heated to about 220° C., and the sealing member  30  is thermocompression bonded onto a front surface of the front wall portion  10   c  while bending the sealing member  30  along the front wall portion  10   c  such that the front surface portion  30   b  is perpendicular to the ceiling surface portion  30   a . In the sealing member  30 , the sealant  15  starts to melt by surrounding heat, and hence the aluminum foil  130  is rendered deformable. Then, the base  10  is cooled thereby mounting the sealing member  30  on the base  10 . When mounting the sealing member  30 , the melted sealant  15  on the front end region  11   a  and the back surface of the sealing member  30  comes into contact with the gas absorbent  49 , and hence the gas absorbent  49  can be adhered to the sealant  15  on the front end region  11   a  and the back surface of the sealing member  30  after cooling. Thus, the sealing member  30  is formed in a shape shown in  FIG. 2 . The semiconductor laser apparatus  100  is formed in the aforementioned manner. 
     According to the first embodiment, as hereinabove described, surfaces of the resin base body  10   a , the outer periphery of the PD  42 , the metal lead frames  11  to  13  and so on located in the sealed space (closed space surrounded by the base  10  and the sealing member  30 ) of the package  90  are completely covered with the covering agent  16  made of the EVOH resin. Thus, the covering agent  16  can block volatile organic gas from penetrating into the sealed space of the package  90  even if the volatile organic gas is generated from a material (polyamide resin) of the base  10 , the conductive adhesive layer  5  (Ag paste) or the like. Further, even if low molecular siloxane, volatile organic gas or the like existing outside the semiconductor laser apparatus  100  (in the atmosphere) penetrates into the components of the package  90 , the covering agent  16  can inhibit the low molecular siloxane, the volatile organic gas or the like from entering the package  90 . Further, the EVOH resin hardly generates the aforementioned volatile component, and hence the semiconductor laser chip  20  in the package  90  is not exposed to the organic gas or the like. Consequently, the adherent substance can be inhibited from being formed on a laser emitting facet, and hence the semiconductor laser chip  20  can be inhibited from deterioration. Especially in the blue-violet semiconductor laser chip  20  having a short lasing wavelength and requiring a higher output power, an adherent substance is easily formed on a laser emitting facet thereof, and hence the use of the covering agent  16  is highly effective. 
     The base  10  is made of polyamide resin, whereby the manufacturing process can be simplified as compared with a case where the package is made of a conventional metal material. The semiconductor laser apparatus  100  can be inexpensively manufactured due to a reduced material cost and the simplified manufacturing process. 
     A surface of the front end region  11   a  of the lead frame  11  other than a region onto which the submount  40  mounted with the blue-violet semiconductor laser chip  20  is bonded is covered with the covering agent  16 . Thus, contaminations attached to the surface of the front end region  11   a  other than the region onto which the submount  40  is bonded in the manufacturing process can also be covered with the covering agent  16 . Thus, the inside of the sealed space of the package  90  can be kept cleaner. 
     The covering agent  16  continuously covers the inner surface (the inner surfaces of the front wall portion  10   c , the pair of side wall portions  10   f  and the inner wall portion  10   g  and the bottom surface of the recess portion  10   b ) of the recess portion  10   b , the surface of the front end region  11   a  other than the portions onto which the submount  40  and the PD  42  are bonded and the surfaces of the front end regions  12   a  and  13   a . Thus, the surfaces of the members constituting the package  90  located in the sealed space are reliably covered with the covering agent  16  with no clearance, and hence the covering agent  16  can reliably block the volatile organic gas from penetrating into the package  90 . 
     A surface of the conductive adhesive layer  5  fixing the PD  42  exposed in the sealed space is covered with the covering agent  16 , and hence the covering agent  16  can block volatile organic gas from penetrating into the package  90  even if the volatile organic gas is generated from the conductive adhesive layer  5  of Ag paste or the like. Consequently, formation of an adherent substance on the photodetecting surface (p-type region) of the PD  42  in addition to the laser emitting facet of the blue-violet semiconductor laser chip  20  can be inhibited, and hence output of the laser beam from the blue-violet semiconductor laser chip  20  can be accurately controlled with the PD  42 . 
     The sealant  15  made of the EVOH resin is formed on the entire inner surface  30   c . In this case, the substantially entire inner surface  30   c  of the sealing member  30  made of the aluminum foil having a side cross section bent in a substantially L-shaped manner from the upper surface  10   i  of the base  10  to the front wall portion  10   c  is covered with the sealant  15 . Thus, contaminants or the like attached to the surface (inner surface  30   c ) of the sealing member  30  on a side of the sealed space are covered with the sealant  15 , and hence the sealed space of the package  90  can be inhibited from being filled with organic gas generated from these contaminants, and the contaminants can be inhibited from being detached from the surface of the sealing member  30  to fill the sealed space. Further, the physical strength (rigidity) is increased by the sealant  15  provided on the entire inner surface  30   c  even if the sealing member  30  is made of the aluminum foil  130  in the form of a thin film normally insufficient for the component of the package  90 . Consequently, the sealing member  30  having a prescribed magnitude of rigidity can be easily made even if a low-cost metal foil is employed. Further, unnecessary deformation in the manufacturing process can be prevented by increasing the rigidity. Further, handling in the manufacturing process becomes easier. 
     The base  10 , the sealing member  30  and the light transmission portion  35  are bonded to each other through the sealant  15  made of the EVOH resin. This resin material with excellent gas barrier properties can inhibit low molecular siloxane, volatile organic gas or the like existing outside the semiconductor laser apparatus  100  (in the atmosphere) from penetrating into the sealant  15  and entering the package  90 . Consequently, the blue-violet semiconductor laser chip  20  can be further inhibited from deterioration. 
     The light transmission portion  35  is mounted on the sealing member  30  through the sealant  15 . In other words, the light transmission portion  35  and the sealing member  30  are bonded to each other with the sealant  15  without employing an adhesive such as an acrylic resin adhesive or an epoxy resin adhesive, and hence the blue-violet semiconductor laser chip  20  sealed in the package  90  is not exposed to organic gas generated by the adhesive. Therefore, the blue-violet semiconductor laser chip  20  can be effectively inhibited from deterioration. 
     The light transmission portion  35  is bonded to the sealing member  30  with the sealant  15  arranged on the front surface portion  30   b  other than the hole  34  (window portion) formed in the sealing member  30 . Thus, the package  90  can be easily sealed with the light transmission portion  35  for emitting the laser beam without harmful effects such as contact of the laser beam with the sealant  15 . 
     The aforementioned sealant  15  made of the EVOH resin is a resin material having a property of melting by heat (about 220° C.), and hence the sealant  15  can be easily applied to a bonded portion of the sealing member  30  and the light transmission portion  35  and a bonded portion of the sealing member  30  and the base  10 . The aforementioned members can be easily bonded to each other by hardening of the sealant  15  following removal of heat (cooling). Thus, the package  90  can be sealed by bonding the base  10 , the sealing member  30  and the light transmission portion  35  to each other without requiring a complicated manufacturing process. 
     In order to confirm usefulness of employing the EVOH resin as the sealant  15  and the covering agent  16 , the following experiment was performed. First, the blue-violet semiconductor laser chip  20  was mounted on a metal stem (base) having a diameter (outer diameter) of 9 mm, and in a state where a pellet of the EVOH resin cut to weigh about 5 mg was put on an inner surface of a metal cap (with a glass window), the stem was sealed with the cap. Then, an operation test was performed by emitting a laser beam adjusted to 10 mW output power by Automatic Power Control (APC) from the blue-violet semiconductor laser chip  20  for 250 hours under a condition of 70° C. Consequently, an operating current of a semiconductor laser apparatus did not remarkably change even after 250 hours. As a comparative example, an operation test was performed in a semiconductor laser apparatus having the semiconductor laser chip sealed without putting the EVOH resin on the inner surface of the cap. The operating current was not remarkably different from that in the comparative example after 250 hours. From these results, it has been confirmed that the EVOH resin hardly generates organic gas or the like, and usefulness of employing the EVOH resin as the sealant  15  and the covering agent  16  has been confirmed. 
     The sealing member  30  is mounted on the base  10  to cover the semiconductor laser chip, and the sealing member  30  and the light transmission portion  35  are bonded to each other through the sealant  15 . Thus, a bonding state of the sealant  15  can be confirmed through the light transmission portion  35  having translucence when the sealing member  30  and the light transmission portion  35  are bonded to each other with the sealant  15 , and hence the sealing member  30  and the light transmission portion  35  can be reliably bonded to each other without formation of air bubbles in the sealant  15 . Consequently, adhesiveness between the sealing member  30  and the light transmission portion  35  in the bonded portion can be increased. The light transmission portion  35  is provided at a position separated from the metal wires  91  and  92 , and hence the light transmission portion  35  is hardly influenced by heat generated in melting solder of the metal wires  91  and  92 . Considering that the EVOH resin has thermoplasticity, the use of the sealant  15  in the present invention for bonding the light transmission portion  35  insusceptible to heat is effective. 
     The sealing member  30  and the light transmission portion  35  are thermocompression bonded to each other with the sealant  15 , and thereafter the sealing member  30  and the base  10  are thermocompression bonded to each other with the sealant  15 . In other words, the sealant  15  made of the EVOH resin, handling of which is easy in the manufacturing process, is employed in the manufacturing process of the semiconductor laser apparatus  100 , and hence the package  90  can be sealed by bonding the base  10 , the sealing member  30  and the light transmission portion  35  to each other without requiring a complicated manufacturing process. 
     The gas absorbent  49  is provided in the package  90 , whereby volatile organic gas generated by the base body  10   a  can be absorbed by the gas absorbent  49 . Thus, a concentration of organic gas in the package  90  can be reduced. Consequently, the blue-violet semiconductor laser chip  20  can be more reliably inhibited from deterioration. 
     The gas absorbent  49  is sandwiched in contact with the covering agent  16  on the front end region  11   a  and the sealant  15  on the inner surface  30   c  of the sealing member  30  in the sealed space (recess portion  10   b ) to be fixed. Thus, the gas absorbent  49  can be prevented from easily moving in the sealed space, and hence contact of the laser beam from the blue-violet semiconductor laser chip  20  with the gas absorbent  49  can be easily prevented. 
     Modification of First Embodiment 
     A semiconductor laser apparatus  105  according to a modification of the first embodiment is now described. In this semiconductor laser apparatus  105 , a sealing member  30  is made of aluminum foil with a thickness of about 50 μm, as shown in  FIG. 8 . At this time, a sealant  15  is not applied onto an inner surface  30   c  of the sealing member  30  located in sealed space of a package  90 , and a surface of the aluminum foil is exposed in the sealed space. On the other hand, the sealant  15  is applied with a prescribed thickness onto a peripheral region (a region near an inner wall portion  10   g  and respective upper surfaces of a pair of side wall portions  10   f  and a front wall portion  10   c ) of an opening  10   e  in an upper surface  10   i  of a base body  10   a  and a peripheral region of an opening  10   d  in the front surface (an outer surface (on an A 1  side) of the front wall portion  10   c ) so as to surround the peripheries of the openings  10   e  and  10   d  shown in  FIG. 1 . In this state, the sealing member  30  is mounted on a base  10  by bringing the vicinity of an outer edge of the inner surface  30   c  of a ceiling surface portion  30   a  and a front surface portion  30   b  into close contact with the sealant  15 . The remaining structure of the semiconductor laser apparatus  105  according to the modification of the first embodiment is substantially similar to that of the semiconductor laser apparatus  100  according to the first embodiment and denoted by the same reference numerals in the figure. 
     In a manufacturing process of the semiconductor laser apparatus  105 , a light transmission portion  35  is bonded onto an aluminum foil  130  (see  FIG. 5 ) having a lower surface  130   b  onto which the sealant  15  is not applied, similarly to the first embodiment. After the sealing member  30  similar to that of the first embodiment is prepared, the front surface portion  30   b  is bent in a direction perpendicular to the ceiling surface portion  30   a  such that the light transmission portion  35  is located outside. Thus, the sealing member  30  is previously formed in a shape shown in  FIG. 8  before the same is thermocompression bonded to the base  10 , dissimilarly to the first embodiment. 
     Thereafter, the sealant  15  continuously covering the periphery (the region near the inner wall portion  10   g  and the respective upper surfaces of the pair of side wall portions  10   f  and the front wall portion  10   c ) of the opening  10   e  in the upper surface  10   i  and the periphery of the opening  10   d  in the front surface (the outer surface of the front wall portion  10   c ) is so applied as to surround the peripheries of the openings  10   e  and  10   d  of the base  10  in a state where the base  10  is heated to about 220° C. In a state where the sealant  15  is melted by heat, the sealing member  30  is thermocompression bonded to the base  10 . Thereafter, the base  10  is cooled, whereby the sealing member  30  is mounted on the base  10 . 
     The remaining manufacturing process is substantially similar to that of the first embodiment. The effects of the modification of the first embodiment are similar to those of the first embodiment. 
     Second Embodiment 
     A semiconductor laser apparatus  200  according to a second embodiment of the present invention is now described. In this semiconductor laser apparatus  200 , as shown in  FIGS. 9 and 10 , a package  90  has a base  10 , and a sealing member  45  and a window member  46  both mounted on the base  10 , covering a blue-violet semiconductor laser chip  20  from upper (a C 2  side) and front (an A 1  side) sides, respectively. While a gas absorbent  49  (see  FIG. 1 ) is not provided in a recess portion  10   b  in the semiconductor laser apparatus  200 , the gas absorbent  49  may be provided in the recess portion  10   b.    
     The sealing member  45  is made of Cu alloy foil such as nickel silver with a thickness t 3  of about 15 μm. The sealing member  45  has a planar shape substantially identical to a planar shape of a base body  10   a , and a width W 21  at the back and a width W 22  at the front. A sealant  15  having a thickness of about 0.2 mm is applied onto a substantially entire region of a back surface  45   c  of the sealing member  45 . 
     The window member  46  is made of a tabular glass plate of borosilicate glass (hard glass). The window member  46  has a thickness t 4  (in a direction A) of about 0.25 mm, a width W 22  (in a direction B) and a height W 23  (in a direction C) substantially equal to a depth (t 1 / 2 ) of the recess portion  10   b  and is mounted in an opening  10   d . At this time, the sealant  15  continuously covering an inner surface of the opening  10   d  (an upper surface of a front end region  11   a  of a lead frame  11  in the opening  10   d  and respective inner surfaces of a pair of side wall portions  10   f ) is applied with a prescribed thickness between the window member  46  and the base body  10   a . In this state, the window member  46  is mounted while bringing a lower surface  46   a  and both side surfaces  46   c  into close contact with the sealant  15 . Dielectric films  31  are formed on surfaces (on A 1  and A 2  sides) of the window member  46 . 
     Then, the sealing member  45  is mounted on the base  10  from an upper side of an opening  10   e . In other words, the sealing member  45  is mounted on the base  10  through the sealant  15  in an upper surface  10   i  (a region near an inner wall portion  10   g  and respective upper surfaces of the pair of side wall portions  10   f ) of the base body  10   a  and an upper surface  46   b  of the window member  46 . Heat radiation portions  211   d  are provided on back regions of the base body  10   a.    
     A PD  42  is arranged on a side of a light-reflecting surface of the blue-violet semiconductor laser chip  20  in a back portion (on the A 2  side) of a submount  40  such that a photodetecting surface faces upward (in a direction C 2 ). A lower surface (n-type region) of the PD  42  is electrically connected to the submount  40 . The remaining structure of the semiconductor laser apparatus  200  is substantially similar to that of the semiconductor laser apparatus  100  according to the first embodiment and denoted by the same reference numerals in the figures. 
     In a manufacturing process of the semiconductor laser apparatus  200 , a lead frame in which the heat radiation portions  211   d  are repeatedly patterned together with lead frames  11  to  13  is first formed, and thereafter the base body  10   a  is molded by a resin molding apparatus. The base body  10   a  is so molded that a front end portion  210   c  is aligned on the same plane as a front end surface  211   e  of the front end region  11   a  of the lead frame  11 . 
     Thereafter, the sealant  15  is applied onto the inner surface of the opening  10   d  (the upper surface of the front end region  11   a  in the opening  10   d  and the respective inner surfaces of the pair of side wall portions  10   f ) in a state where the base  10  is heated to about 220° C. In a state where the sealant  15  is melted by heat, the window member  46  is thermocompression bonded and mounted by being fitted into the opening  10   d . Thus, the window member  46  is mounted on the base body  10   a  while bringing the lower surface  46   a  and the both side surfaces  46   c  into close contact with the upper surface of the front end region  11   a  and the inner surfaces of the side wall portions  10   f  through the sealant  15 . 
     Thereafter, UV cleaning treatment or heating treatment at about 200° C. in vacuum is performed on the base  10 . Thus, contaminations attached to the recess portion  10   b  in the manufacturing process are removed, or moisture or a solvent contained in polyamide resin is evaporated to be removed. 
     Thereafter, the submount  40  to which the blue-violet semiconductor laser chip  20  and the PD  42  are bonded with a conductive adhesive layer (not shown) is bonded onto a substantially central portion (in a lateral direction) of the upper surface of the front end region  11   a . At this time, a light-emitting surface of the blue-violet semiconductor laser chip  20  faces the window member  46 , and the light-reflecting surface of the blue-violet semiconductor laser chip  20  and the PD  42  face the inner wall portion  10   g.    
     Thereafter, a p-side electrode  21  of the blue-violet semiconductor laser chip  20  and a front end region  12   a  of the lead frame  12  are connected with each other through a metal wire  91 . An upper surface of the PD  42  and a front end region  13   a  of the lead frame  13  are connected with each other through a metal wire  92 . 
     The sealant  15  (EVOH resin) is applied with a thickness of about 0.2 mm onto the entire back surface  45   c  heated to about 220° C., and a nickel silver sheet is cut out to have the planar shape (see  FIG. 9 ) substantially identical to the planar shape of the base body  10   a  after cooling, whereby the sealing member  45  is formed. 
     Thereafter, the sealing member  45  is thermocompression bonded onto the upper surface  10   i  and the upper surface  46   b  to cover the opening  10   d  in a state where the base  10  is heated to about 220° C. Thus, the sealing member  45  is mounted on the base body  10   a  while bringing the back surface  45   c  into close contact with the upper surface  10   i  and the upper surface  46   b  through the sealant  15 . The remaining manufacturing process is substantially similar to that of the first embodiment. 
     According to the second embodiment, as hereinabove described, the opening  10   d  of the base body  10   a  is sealed with the window member  46  through the sealant  15 , and the opening  10   e  of the base body  10   a  is sealed with the sealing member  45  through the sealant  15 . The window member  46  and the sealing member  45  can be further strongly mounted on the base body  10   a  with no clearance by employing the sealant  15 , and hence the package  90  can be reliably sealed. Thus, the blue-violet semiconductor laser chip  20  in the package  90  can be inhibited from deterioration. 
     Further, the openings  10   d  and  10   e  which open from the upper surface  10   i  to the front end portion  210   c  of the base body  10   a  are sealed with the window member  46  and the sealing member  45 , respectively, and hence clearances are hardly generated in the boundaries of the upper surface  10   i  of the opening  10   e  and the front end portion  210   c  of the opening  10   d . Thus, the package  90  can be reliably sealed, and hence the blue-violet semiconductor laser chip  20  in the package  90  can be reliably inhibited from deterioration. 
     Further, the window member  46  and the sealing member  45  are mounted to the base body  10   a  through the sealant  15 , whereby the semiconductor laser apparatus  200  can be easily manufactured with existing manufacturing equipments without increasing the manufacturing cost. 
     Third Embodiment 
     A semiconductor laser apparatus  300  according to a third embodiment of the present invention is now described. In this semiconductor laser apparatus  300 , a package  90  is constituted by a metal base  310  and a metal cap  330 , as shown in  FIGS. 11 and 12 . The cap  330  is an example of the “sealing member” in the present invention. 
     The base  310  is made of kovar, which is an Fe—Ni—Co alloy with an Ni—Au plated surface. The base  310  has a stem portion  310   a  with a prescribed thickness (in a direction A) formed in a substantially disc shape and a protruding block  310   b  protruding forward (in a laser beam-emitting direction (direction A 1 )), formed on a lower region (C 1  side) of a front surface  310   c  of the stem portion  310   a  and having a semilunar cross section (in a width direction (direction B)). 
     The base  310  is provided with a lead frame  11  conducting to the stem portion  310   a  and lead frames  12  and  13  so arranged as to pass through the stem portion  310   a  from the front side to the back side (A 2  side) in a state where the lead frames  12  and  13  are hermetically-closed by low-melting-point glass  319  such as kovar glass and isolated from the lead frame  11 . Respective back end regions of the lead frames  11  to  13  extending backward are exposed from a back surface  310   h  on a back portion of the stem portion  310   a.    
     A blue-violet semiconductor laser chip  20  is mounted on a substantially central portion of an upper surface of the protruding block  310   b  through a submount  40 . A PD  42  is arranged on the front surface  310   c  of the stem portion  310   a  at a position opposed to a light-reflecting surface (A 2  side) of the blue-violet semiconductor laser chip  20  such that a photodetecting surface faces forward. A lower surface (n-type region) of the PD  42  is electrically connected to the stem portion  310   a  through a conductive adhesive layer  5 . A covering agent  16  is circumferentially applied to cover the outer periphery of the PD  42  excluding the photodetecting surface, a surface of the conductive adhesive layer  5  protruding along this outer periphery and a surface of the stem portion  310   a  in the periphery of the conductive adhesive layer  5 . 
     The cap  330  has a body made of kovar with an Ni-plated surface and has a side wall portion  330   a  substantially cylindrically formed and a bottom portion  330   b  closing one side (A 1  side) of the side wall portion  330   a . A mounting portion  330   g  is circumferentially formed on an opening side (A 2  side) of the side wall portion  330   a  of the cap  330 . A protrusion  330   i  employed in resistance welding is formed on an end surface  330   h  of the mounting portion  330   g.    
     A hole  34  is provided in a substantially central portion of the bottom portion  330   b  of the cap  330 . A rectangular light transmission portion  35  made of borosilicate glass is provided to cover the hole  34  from the outside (A 1  side) of the bottom portion  330   b . At this time, the light transmission portion  35  is bonded to the bottom portion  330   b  through a sealant  15  with a thickness of about 0.1 mm applied onto an outer surface of the bottom portion  330   b  other than the hole  34 . 
     As shown in  FIG. 12 , a covering agent  18  is circumferentially piled up so as to come into contact with the bottom portion  330   b , the sealant  15  and the light transmission portion  35  along an outer edge of the light transmission portion  35 . In other words, a side surface (outer surface) of the sealant  15  for bonding the bottom portion  330   b  and the light transmission portion  35  to each other is covered with the covering agent  18  made of a material having smaller water vapor permeability than the sealant  15 . A material having low water vapor permeability is selected from among light curing or thermosetting resins made of epoxy resin or the like and employed as this covering agent  18 . Therefore, the covering agent  18  prevents the sealant  15  from coming into direct contact with outside air. The covering agent  16  is not applied onto an inner surface  330   c  of the cap  330 . 
     The remaining structure of the semiconductor laser apparatus  300  is substantially similar to that of the semiconductor laser apparatus  100  according to the first embodiment and denoted by the same reference numerals in the figures. 
     In a manufacturing process of the semiconductor laser apparatus  300 , the submount  40  to which the blue-violet semiconductor laser chip  20  is bonded with a conductive adhesive layer (not shown) is first bonded onto the protruding block  310   b  of the base  310  provided with the lead frames  11  to  13 , as shown in  FIG. 11 . Then, the lower surface (n-type region) of the PD  42  is bonded onto the front surface  310   c  behind the submount  40  and above the protruding block  310   b  with the conductive adhesive layer  5 . 
     Thereafter, the outer periphery of the PD  42  is covered with a film of the covering agent  16  (EVOH resin) previously cut in a frame shape from an upper side of the PD  42  not to come into contact with the photodetecting surface. In this state, the base  310  is heated to about 200° C., whereby the covering agent  16  is melted and circumferentially covers the outer periphery of the PD  42  excluding the photodetecting surface, the surface of the conductive adhesive layer  5  protruding along this outer periphery and the surface of the stem portion  310   a  in the periphery of the conductive adhesive layer  5 . After cooling the stem portion  310   a , metal wires  91  and  92  are bonded. 
     Thereafter, the sealant  15  is applied around the hole  34  from the outside of the bottom portion  330   b  in a state where the cap  330  is heated to about 220° C. In a state where the sealant  15  is melted by heat, the light transmission portion  35  is press-bonded through the sealant  15  to cover the hole  34 , and thereafter the cap  330  is cooled. Then, the covering agent  18  is piled up to cover the sealant  15  exposed along the outer edge of the light transmission portion  35 . The cap  330  is formed in the aforementioned manner. 
     Finally, the cap  330  is mounted on the base  310  along arrow P (in a direction A 2 ) shown in  FIG. 11 . At this time, the end surface  330   h  of the mounting portion  330   g  is mounted by resistance welding with a cap seal machine while circumferentially bringing the end surface  330   h  of the mounting portion  330   g  into contact with the vicinity of an outer edge of the stem portion  310   a . Thus, the blue-violet semiconductor laser chip  20  is hermetically sealed. The remaining manufacturing process is substantially similar to that of the first embodiment. The semiconductor laser apparatus  300  is formed in the aforementioned manner. 
     According to the third embodiment, as hereinabove described, the cap  330  is cylindrically formed with the bottom portion  330   b , and hence the package  90  can be sealed in a state where the blue-violet semiconductor laser chip  20  is circumferentially surrounded by an inner surface of the side wall portion  330   a  extending in a longitudinal direction (an extensional direction of a cylindrical shape (direction A)) of the cap  330 . 
     The side surface (outer surface) of the sealant  15  for bonding the cap  330  (bottom portion  330   b ) and the light transmission portion  35  to each other is covered with the covering agent  18  made of a material having smaller water vapor permeability than the sealant  15 . Thus, the covering agent  18  can reliably inhibit moisture or the like existing outside (in the atmosphere) from entering the package  90  through the sealant  15  from a bonded portion of the bottom portion  330   b  and the light transmission portion  35 . 
     The cap  330  can be mounted on the stem portion  310   a  by resistance welding with a cap seal machine, similarly to a normal cap mounted with a light transmission portion through low-melting-point glass, and hence the semiconductor laser apparatus  300  can be easily manufactured with existing manufacturing equipments without increasing the manufacturing cost. The remaining effects of the third embodiment are similar to those of the first embodiment. 
     Modification of Third Embodiment 
     A semiconductor laser apparatus  305  according to a modification of the third embodiment is now described. In this semiconductor laser apparatus  305 , as shown in  FIG. 13 , a light transmission portion  35  is bonded through a sealant  15  to cover a hole  34  from the inside (inner surface  330   c ) of a bottom portion  330   b  of a cap  330 . A covering agent  18  is circumferentially piled up to come into contact with the hole  34 , the sealant  15  and the light transmission portion  35  in the vicinity of an inner surface of the hole  34  on which the light transmission portion  35  is mounted from inside. In other words, a side surface (inner surface) of the sealant  15  for bonding the bottom portion  330   b  and the light transmission portion  35  is covered with the covering agent  18 . The remaining structure of the semiconductor laser apparatus  305  according to the modification of the third embodiment is substantially similar to that of the semiconductor laser apparatus  300  according to the third embodiment and denoted by the same reference numerals in the figure. 
     In a manufacturing process of the semiconductor laser apparatus  305  according to the modification of the third embodiment, the light transmission portion  35  is thermocompression bonded onto the inner surface  330   c  in the bottom portion  330   b  of the cap  330  through the sealant  15 , and thereafter the covering agent  18  is piled up to cover the sealant  15  exposed on a side of the inner surface of the hole  34 . The remaining manufacturing process is substantially similar to that of the third embodiment. The effects of the modification of the third embodiment are similar to those of the third embodiment. 
     Fourth Embodiment 
     A semiconductor laser apparatus  400  according to a fourth embodiment of the present invention is now described. In this semiconductor laser apparatus  400 , as shown in  FIG. 14 , a package  90  is constituted by a base  410  and a cap  430  both made of polyamide resin. The cap  430  is an example of the “sealing member” in the present invention. 
     The base  410  has a substantially cylindrical header portion  410   a  with an outer diameter D 1  and a protruding block  410   b  extending forward (in a direction A 1 ) from a lower half portion of a front surface  410   c  of the header portion  410   a . As shown in  FIG. 15 , edges  410   g  where an outer peripheral surface  410   k  and front surfaces  410   c  and  410   e  of the base  410  intersect are chamfered. 
     A lead frame  11  is integrally formed with a pair of heat radiation portions  411   d  connected to a front end region  11   a . Specifically, the lead frame  11  is formed with connecting portions  411   c  extending backward (in a direction A 2 ) from both ends of the front end region  11   a  in a width direction (on B 2  and B 1  sides). The connecting portions  411   c  extend backward from the front end region  11   a  outside (on the B 2  and B 1  sides of) lead frames  12  and  13  and pass through a back surface  410   h  after hiding in the header portion  410   a  from the front surface  410   c  of the base  410 . The heat radiation portions  411   d  are connected to back end regions of the connecting portions  411   c  exposed from the back surface  410   h  of the base  410 . The heat radiation portions  411   d  extend forward (in the direction A 1 ) from positions connected to the connecting portions  411   c . Therefore, the pair of heat radiation portions  411   d  extend substantially parallel to the outer peripheral surface  410   k  at an interval of a width W 6  from the outer peripheral surface  410   k  of the base  410 , as shown in  FIG. 14 . 
     The cap  430  has a substantially cylindrical side wall portion  430   a  with an inner diameter D 2  and an outer diameter D 3  and a bottom portion  430   b  closing one side (A 1  side) of the side wall portion  430   a . The side wall portion  430   a  has a thickness t 1  of about 0.5 mm, and the bottom portion  430   b  has a thickness t 2  (t 2 ≧t 1 ) slightly larger than the thickness t 1 . The inner diameter D 2  of the cap  430  is slightly smaller than the outer diameter D 1  of the header portion  410   a . The mounting portion  330   g  as in the third embodiment is not formed on an opening side (A 2  side) of the side wall portion  430   a . A sealant  15  is applied with a thickness of about 0.3 mm on a substantially entire region of an inner surface  430   c  of the cap  430  excluding a hole  34 . 
     In this state, the header portion  410   a  is slid to the cap  430  from an A 2  side toward an A 1  side to be fitted into the cap  430  in the semiconductor laser apparatus  400 , as shown in  FIG. 15 . In other words, the outer peripheral surface  410   k  of the header portion  410   a  and the inner surface  430   c  of the cap  430  are circularly fitted into each other through the sealant  15 . Thus, a blue-violet semiconductor laser chip  20  is hermetically sealed in the package  90 . 
     A covering agent  16  is applied onto a surface of each member located in sealed space (closed space surrounded by the base  410  and the cap  430 ) of the package  90 . Specifically, the covering agent  16  continuously covers the protruding block  410   b , the front surface  410   c , the front surface  410   e  and the edges  410   g  of the base  410 , a surface of the front end region  11   a  other than a portion onto which a submount  40  is bonded and surfaces of front end regions  12   a  and  13   a  to which metal wires are bonded with no clearance. Therefore, the surfaces of the base  410  of resin located in the sealed space of the package  90  and the front end regions  12   a  and  13   a  to which the metal wires are bonded are completely covered with the covering agent  16 . The sealant  15  exposed in the sealed space of the package  90  of the aforementioned sealant  15  applied onto the inner surface  430   c  of the cap  430  also serves as the “covering agent” in the present invention. It is not necessary to cover a surface of a metal member with the covering agent  16 . 
     Clearances (notches) each having a width W 6  larger than the thickness t 1  of the side wall portion  430   a  of the cap  430  are formed between the outer periphery surface  410   k  of the base  410  and the heat radiation portions  411   d  on both sides of the outer periphery surface  410   k . Therefore, the heat radiation portions  411   d  are arranged outside the cap  430  without interfering in (coming into contact with) the side wall portion  430   a  of the cap  430  in a state where the cap  430  is fitted into the base  410 . The remaining structure of the semiconductor laser apparatus  400  according to the fourth embodiment is substantially similar to that of the semiconductor laser apparatus  300  according to the third embodiment and denoted by the same reference numerals in the figures. 
     In a manufacturing process of the semiconductor laser apparatus  400  according to the fourth embodiment, the base  410  having the aforementioned shape is first molded through the manufacturing process similar to that of the second embodiment. Thereafter, the submount  40  to which the blue-violet semiconductor laser device  20  and the PD  42  are bonded is bonded onto the protruding block  410   b  of the base  410  provided with the lead frames  11  to  13  through a conductive adhesive layer (not shown). 
     Metal wires  91  and  92  are bonded, and thereafter the covering agent  16  is applied to continuously cover the protruding block  410   b , the front surface  410   c , the front surface  410   e  and the edges  410   g  of the base  410 , the surface of the front end region  11   a  other than the portion onto which the submount  40  is bonded and the surfaces of the front end regions  12   a  and  13   a  to which the metal wires are bonded in a state where the base  410  is heated to about 230° C. 
     Meanwhile, polyamide resin is poured into a first mold (not shown) having a prescribed shape and hardened. Thus, a concave frame body  431  (see  FIG. 16 ) becoming the cap  430 , having the hole  34  in a bottom portion  431   b  is molded. EVOH resin heated to about 220° C. is poured into a second mold (not shown) having a prescribed shape, and thereafter cooled, whereby a concave frame body  315  (see  FIG. 16 ) made of EVOH resin is molded. At this time, the hole  34  is also formed in a bottom portion  315   b  of the frame body  315 . 
     The frame body  315  is covered with the frame body  431  from above (C 2  side) in a state where the bottom portions  431   b  and  315   b  are opposed to each other and set between a movable upper mold  401  and a stationary lower mold  402 . Thereafter, the movable upper mold  401  is fitted into the stationary lower mold  402  in a state where the molds are heated to about 220° C., as shown in  FIG. 17 . At this time, the frame bodies are thermocompression bonded to each other in a state where a light transmission portion  35  of glass formed in a substantially disc shape is placed on an upper surface (on the C 2  side) of the stationary lower mold  402 . Then, the molds are cooled thereby molding the cap  430 . Drafts are provided on an inner surface of the movable upper mold  401  and an outer surface of the stationary lower mold  402 . Thus, in the molded cap  430 , an outer diameter of the side wall portion  430   a  (an inner diameter of the inner surface  430   c ) on a side (A 2  side) where the side wall portion  430   a  opens is slightly larger than an outer diameter of the side wall portion  430   a  (an inner diameter of the inner surface  430   c ) in the vicinity of the bottom portion  430   b.    
     Thereafter, the base  410  is linearly slid to the cap  430  to be fitted into the cap  430  in a state where the base  410  is heated to about 200° C. thereby sealing the package  90 . The remaining manufacturing process is substantially similar to that of the third embodiment. 
     According to the fourth embodiment, as hereinabove described, the sealant  15  is formed on the entire inner surface  430   c  becoming a back surface of the cap  430 , and hence the sealant  15  can effectively inhibit volatile organic gas from penetrating into the sealed space of the package  90  even if the volatile organic gas is generated from a resin material of the cap  430 . 
     The sealant  15  is formed on the entire inner surface  430   c  of the cap  430 , and hence the physical strength (rigidity) is increased by the sealant  15  even if a thickness of the molded polyamide resin is small. Consequently, the cap  430  having a prescribed magnitude of rigidity can be easily made. 
     The blue-violet semiconductor laser chip  20  is sealed by fitting the base  410  and the cap  430  into each other, whereby the inner surface  430   c  of the cap  430  can be easily brought into close contact with the outer peripheral surface  410   k  of the base  410 , and hence the package  90  can be easily sealed. In other words, it is not necessary to employ an additional adhesive or the like for sealing, and hence generation of organic gas can be inhibited. The remaining effects of the fourth embodiment are similar to those of the third embodiment. 
     Modification of Fourth Embodiment 
     A semiconductor laser apparatus  405  according to a modification of the fourth embodiment is now described. In this semiconductor laser apparatus  405 , a cap  430  is made of aluminum foil. The remaining structure of the semiconductor laser apparatus  405  according to the modification of the fourth embodiment is substantially similar to that of the semiconductor laser apparatus  400  according to the fourth embodiment and denoted by the same reference numerals in the figures. 
     In a manufacturing process of the semiconductor laser apparatus  405  according to the modification of the fourth embodiment, as shown in  FIG. 18 , in a state where a sheet-like aluminum foil  130  having a thickness of about 20 μm is heated to about 220° C., a sealant  15  is applied with a thickness of about 0.2 mm on an entire lower (back) surface  131   b  and cooled, and thereafter a hole  34  is formed. Then, in a state where the aluminum foil  130  is set such that the sealant  15  faces downward (in a direction C 1 ) between a movable upper mold  401  and a stationary lower mold  402 , the movable upper mold  401  is fitted into the stationary lower mold  402 . Thus, the cap  430  is molded. Corrugations are formed on an outer surface (inner surface) of a side wall portion  430   a  of the aluminum foil  130  substantially in the form of a cylinder by molding the cap  430 . The remaining manufacturing process is substantially similar to that of the fourth embodiment. The effects of the modification of the fourth embodiment are similar to those of the fourth embodiment. 
     Fifth Embodiment 
     A semiconductor laser apparatus  500  according to a fifth embodiment of the present invention is now described. In this semiconductor laser apparatus  500 , a package  90  has a base  550 , an Si (100) substrate  510  mounted on the base  550 , surrounding a blue-violet semiconductor laser chip  20  from the side (directions A and B) and sealing glass  560  mounted on the Si (100) substrate  510 , covering the blue-violet semiconductor laser chip  20  from the upper side (C 2  side), as shown in  FIG. 19 . The Si (100) substrate  510  and the sealing glass  560  are examples of the “sealing member” and the “window member” in the present invention, respectively.  FIG. 19  is a sectional view taken along the line  590 - 590  in  FIG. 20 . 
     The base  550  is made of an insulating photo solder mask. The photo solder mask denotes an insulating coating of photosensitive resin becoming insoluble in a solvent or the like by structurally changing only a portion exposed to light. The base  550  closes an opening  501   b  (see  FIG. 21 ) on one side (C 1  side) of the Si (100) substrate  510  having a through hole  501  (see  FIG. 21 ) penetrating in a thickness direction (direction C). At this time, the base  550  is bonded through adhesive resin  551  provided on a lower surface  510   b  of the Si (100) substrate  510 . Thus, a recess portion  511  having an opening  511   a  which opens on the upper side is constituted by the base  550  and the Si (100) substrate  510 . The blue-violet semiconductor laser chip  20  is placed on a submount  40  such that an upper surface  20   b  is located below (on a C 1  side of) an upper surface  510   a  of the Si (100) substrate  510 . The photo solder mask is an example of the “photosensitive resin” in the present invention. 
     The plate-like (tabular) sealing glass  560  is made of borosilicate glass (hard glass) with a thickness of about 500 μm. The sealing glass  560  is mounted on the upper surface  510   a  of the Si (100) substrate  510  through a sealant  15 . In other words, the Si (100) substrate  510  is covered with the sealing glass  560  from the upper surface  510   a  so that the opening  511   a  of the recess portion  511  is closed, and the blue-violet semiconductor laser chip  20  placed on a bottom surface  516  of the recess portion  511  is hermetically sealed in the package  90 . A planar shape of the sealing glass  560  is substantially identical to that of the Si (100) substrate  510 . 
     As shown in  FIG. 19 , in a manufacturing process described later, the Si (100) substrate  510  having a main surface (upper surface  510   a ) inclined at about 9.7° with respect to a substantially (100) plane is anisotropically etched, whereby four inner surfaces  512 ,  513 ,  514  and  515  each having an Si (111) plane are formed on the Si (100) substrate  510 . This Si (100) substrate  510  having the main surface inclined at about 9.7° is employed, whereby the inner surface  512  is inclined with an inclined angle α of about 45° with respect to an upper surface  550   a  (bottom surface  516 ) of the base  550  while the inner surface  513  is inclined with an inclined angle β of about 64.4° with respect to the upper surface  550   a  (bottom surface  516 ). The inner surfaces  514  and  515  (see  FIG. 20 ) each are inclined with an inclined angle of about 54.7° with respect to the upper surface  550   a  (bottom surface  516 ). 
     The four inner surfaces  512 ,  513 ,  514  and  515  and the adhesive resin  551  formed on an upper surface (surface on the C 2  side) of the base  550  constitute the recess portion  511 . The adhesive resin  551  is employed to bond the Si (100) substrate  510  and the base  550 , and the bottom surface  516  of the recess portion  511  is substantially constituted by a part of an upper surface of the adhesive resin  551 , as shown in  FIG. 19 . The Si (100) substrate  510  has high resistivity (an insulating property) and a thickness of about 500 μm from the upper surface  510   a  to the lower surface  510   b.    
     A wiring electrode  531  made of Cu or the like for die-bonding (bonding) the submount  40  is formed on a region (region becoming the bottom surface  516  of the recess portion  511 ) of the upper surface  550   a  of the base  550  (adhesive resin  551 ) exposed in the recess portion  511 . Thus, a back surface (surface on the C 2  side) of the submount  40  is bonded onto a surface of the wiring electrode  531  through a conductive adhesive layer (not shown) at a position deviating along arrow to an A 1  side (a side closer to the inner surface  512 ) from a substantially central portion in the recess portion  511 . The wiring electrode  531  exposed in the recess portion  511  has a larger plane area than the submount  40 , and the submount  40  is placed in a region formed with the wiring electrode  531 . The wiring electrode  531  has an extraction wiring portion  531   a  extending along a direction A 1  from a position on which the submount  40  is placed. 
     A metal reflective film  561  is formed on a surface of a region of the inner surface  512  opposed to a light-emitting surface. Thus, in the semiconductor laser apparatus  500 , a laser beam emitted in the direction A 1  from the light-emitting surface of the blue-violet semiconductor laser chip  20  is reflected upward on the inner surface  512  (metal reflective film  561 ) of the recess portion  511 , and thereafter transmitted through the sealing glass  560  to be emitted outward. The inner surface  512  and the metal reflective film  561  constitute reflecting means for reflecting the laser beam outward. 
     As shown in  FIG. 20 , wiring electrodes  532  and  533  for wire bonding each having a rectangular shape (a size of about 100 μm×about 100 μm) are formed on a region of the bottom surface  516  of the recess portion  511  not formed with the wiring electrode  531 . In other words, the wiring electrode  532  is exposed in a region deviating to the inner surface  514  (B 2  side) between the submount  40  and the inner surface  513 , and the wiring electrode  533  is exposed in a region deviating to the inner surface  515  (B 1  side) between the submount  40  and the inner surface  513 . The wiring electrodes  532  and  533  have extraction wiring portions  532   a  and  533   a  extending along a direction A 2 . 
     Therefore, a first end of a metal wire  91  is bonded to a p-side electrode  21  formed on an upper surface of the blue-violet semiconductor laser chip  20 , and a second end of the metal wire  91  is connected to the wiring electrode  532 . A first end of a metal wire  92  is bonded to an upper surface (p-type region) of a PD  42 , and a second end of the metal wire  92  is connected to the wiring electrode  533 . The PD  42  is formed such that a lower surface (n-type region) and the wiring electrode  531  conduct with each other through an electrode  36  passing through the submount  40  vertically (in the direction C). A first end of a metal wire  93  is bonded to a pad electrode  571  onto which a lower surface (n-side electrode  22 ) of the blue-violet semiconductor laser chip  20  is bonded, and a second end of the metal wire  93  is connected to the wiring electrode  531 . A solder ball  524  made of Au—Sn solder is formed on an end of each of the extraction wiring portions  531   a ,  532   a  and  533   a.    
     A covering agent  16  is applied with a prescribed thickness onto a surface of each member located in sealed space (closed space surrounded by the base  550 , the inner surfaces of the Si (100) substrate  510  and the sealing glass  560 ) of the package  90 . Specifically, the covering agent  16  continuously covers a surface of the adhesive resin  551  in the recess portion  511 , a surface of the wiring electrode  531  other than portions to which the submount  40  and the PD  42  are bonded and surfaces of the wiring electrodes  532  and  533  with no clearance. Therefore, surfaces of the base  550 , the wiring electrodes  531  to  533 , etc. located in the sealed space of the package  90  are completely covered with the covering agent  16 . The remaining structure of the fifth embodiment is substantially similar to that of the first embodiment. 
     A manufacturing process of the semiconductor laser apparatus  500  according to the fifth embodiment is now described with reference to  FIGS. 19 to 23 . 
     As shown in  FIG. 21 , the Si (100) substrate  510  in a wafer state having a thickness D 3  of about 500 μm and the main surface (upper surface  510   a ) inclined at about 9.7° with respect to the substantially (100) plane is prepared. Then, wet etching (anisotropic etching) employing an etching solution such as TMAH is performed on the Si (100) substrate  510  formed with an etching mask (not shown) having a prescribed mask pattern on the upper surface  510   a , thereby forming the through hole  501  penetrating from the upper surface  510   a  to the lower surface  510   b . Thus, a plurality of the through holes  501  having openings  501   a  and  501   b  are formed in the Si (100) substrate  510  in a wafer state. 
     At this time, the four different inner surfaces  512 ,  513 ,  514  and  515  are formed in the through hole  501  by etching corresponding to crystal orientation of Si. The inner surface  512  is an etched surface (inclined surface) inclined at about 45° (angle α) with respect to the upper surface  510   a , and the inner surface  513  is an etched surface (inclined surface) inclined at about 64.4° (angle β) with respect to the upper surface  510   a . The inner surfaces  514  and  515  (see  FIG. 20 ) are etched surfaces inclined at about 54.7° with respect to the upper surface  510   a  of the Si (100) substrate  510 . 
     Thereafter, the metal reflective film  561  is formed by evaporation, sputtering or the like on the region of the inner surface  512  opposed to the light-emitting surface (see  FIG. 19 ) in a state where the blue-violet semiconductor laser chip  20  is placed. 
     Meanwhile, a tabular copper plate  503  having a thickness of about 100 μm is prepared, as shown in  FIG. 22 . An etching mask (not shown) having a prescribed mask pattern is formed on an upper surface of the copper plate  503 , and thereafter wet etching employing an etching solution such as a ferric chloride solution is performed on the copper plate  503 . Thus, the copper plate  503  is etched from the upper and lower surfaces so that the flat portion has a thickness of about 60 μm, and a protrusion  503   a  having a protrusion height of about 20 μm is formed on the upper surface (a surface on the C 2  side). 
     Thereafter, the thermosetting epoxy resin-based adhesive resin  551  is bonded onto the upper surface of the copper plate  503  by lamination with a roll laminator or a hot pressing machine. At this time, the adhesive resin  551  is bonded at a temperature of not more than about 100° C. at which the adhesive resin  551  does not harden completely. Thereafter, a portion of the adhesive resin  551  covering the protrusion  503   a  is removed by O 2  plasma treatment, polishing or the like. 
     Then, as shown in  FIG. 22 , the copper plate  503  is bonded onto the lower surface  510   b  of the Si (100) substrate  510  having the through hole  501  through the adhesive resin  551 , and thereafter the Si (100) substrate  510  and the copper plate  503  are bonded to each other by thermocompression bonding for about 5 minutes under temperature and pressure conditions of about 200° C. and about 1 MPa. Thus, the opening  501   b  (see  FIG. 21 ) of the Si (100) substrate  510  is closed so that the recess portion  511  is formed. The opening  501   a  of the Si (100) substrate  510  is left as the opening  511   a  in the upper portion of the recess portion  511 . 
     Thereafter, the submount  40  to which the blue-violet semiconductor laser chip  20  is previously bonded is bonded onto the surface of the wiring electrode  531 . Then, the A-side electrode  21  of the blue-violet semiconductor laser chip  20  and the wiring electrode  532  are connected with each other through the metal wire  91 , and the p-type region of the PD  42  and the wiring electrode  533  are connected with each other through the metal wire  92 . The pad electrode  571  and the wiring electrode  531  are connected with each other through the metal wire  93  (see  FIG. 20 ). Before the metal wires  91  and  92  are bonded to the wiring electrodes  532  and  533 , a metal film made of Au or the like may be formed on the surfaces of the wiring electrodes  532  and  533 . 
     Thereafter, the covering agent  16  is applied onto the surface of the adhesive resin  551  in the recess portion  511 , the surface of the wiring electrode  531  other than the portions to which the submount  40  and the PD  42  are bonded and the surfaces of the wiring electrodes  532  and  533  in a state where the Si (100) substrate  510  is heated to about 230° C. 
     Thereafter, the sealing glass  560  having a thickness of about 500 μm is bonded to the recess portion  511  of the Si (100) substrate  510  from the upper side by thermocompression bonding, as shown in  FIG. 23 . At this time, the Si (100) substrate  510  and the sealing glass  560  are bonded to each other with the sealant  15  under a temperature condition of at least about 200° C. and not more than about 220° C. Thus, the sealing glass  560  is bonded to the Si (100) substrate  510  through the sealant  15  in the upper surface  510   a  surrounding the opening  511   a  of the recess portion  511 , and hence the inside of the recess portion  511  is hermetically sealed. 
     Thereafter, the lower surface of the copper plate  503  is etched to form a wiring pattern. Thus, the copper plate  503  other than the protrusion  503   a  has a thickness of about 20 μm. Further, an etching mask (not shown) having a prescribed mask pattern is formed on the lower surface of the copper plate  503 , and thereafter wet etching employing a ferric chloride solution is performed on the copper plate  503 , thereby forming the wiring electrodes  531  to  533  having prescribed wiring patterns constituted by the extraction wiring portions  531   a ,  532   a  and  533   a  (see  FIG. 23 ). At this time, the adhesive resin  551  is partially exposed from under the removed copper plate  503 . 
     Thereafter, a photo solder mask having a thickness of about 30 μm is formed on the lower surfaces of the wiring electrodes  531  to  533  and the exposed adhesive resin  551  to cover the lower surfaces of the wiring electrodes  531  to  533 , as shown in  FIG. 23 . At this time, a laminated film of a photo solder mask may be bonded, or a liquid photo solder mask may be applied. Then, a lower surface of the photo solder mask is partially removed, and the solder balls  524  are formed on the ends of the extraction wiring portions  531   a ,  532   a  and  533   a  (see  FIG. 20 ) exposed from the photo solder mask. The base  550  is formed in the aforementioned manner. 
     Finally, in a region outside a region formed with the recess portion  511 , the sealing glass  560  and the Si (100) substrate  510  are cut (diced) in the thickness direction (direction C) along division lines  595  shown in  FIG. 23  with a diamond blade. The semiconductor laser apparatus  500  according to the fifth embodiment shown in  FIG. 20  is formed in the aforementioned manner. 
     According to the fifth embodiment, as hereinabove described, the semiconductor laser apparatus  500  comprises the Si (100) substrate  510  formed with the through hole  501  penetrating in the thickness direction, the sealing glass  560  mounted on the upper surface  510   a  of the Si (100) substrate  510 , sealing the opening  501   a  ( 511   a ) of the through hole  501 , the base  550  mounted on the lower surface  510   b  of the Si (100) substrate  510 , sealing the opening  501   b  of the through hole  501  and the blue-violet semiconductor laser chip  20  placed on the surface of the wiring electrode  531  formed on the base  550  exposed in the opening  501   b  through the submount  40 . Thus, the upper surface  20   b  of the blue-violet semiconductor laser chip  20  placed on the surface of the wiring electrode  531  exposed in the opening  501   b  does not protrude outward (to the C 2  side in  FIG. 19 ) beyond the opening  501   a  ( 511   a ) of the through hole  501 , and hence the blue-violet semiconductor laser chip  20  can operate in a state where the same is hermetically sealed in the through hole  501  by the base  550  and the sealing glass  560 . Thus, the blue-violet semiconductor laser chip  20  is not influenced by moisture in the atmosphere or an organic substance existing in the periphery of the semiconductor laser apparatus  500 , and hence reduction of the reliability of the blue-violet semiconductor laser chip  20  can be inhibited. 
     The laser beam emitted from the blue-violet semiconductor laser chip  20  is reflected by the metal reflective film  561  formed on the inner surface  512  of the through hole  501 , and thereafter transmitted through the sealing glass  560  to be emitted outward. Thus, the inner surface  512 , which is a part of the through hole  501  of the Si (100) substrate  510  fixed onto the base  550  on which the blue-violet semiconductor laser chip  20  is placed through the submount  40 , can also serve the reflecting means of the laser beam. In other words, precision of an optical axis of the laser beam reflected by the metal reflective film  561  formed on the inner surface  512  depends only on an arrangement error in placing the blue-violet semiconductor laser chip  20  on the surface of the wiring electrode  531  formed on the base  550  through the submount  40 , and hence the number of factors causing deviation of the optical axis is reduced so that the magnitude of the deviation of the optical axis can be reduced. 
     The semiconductor laser apparatus  500  comprises the Si (100) substrate  510  formed with the through hole  501 , the base  550  mounted on the lower surface  510   b  of the Si (100) substrate  510 , sealing the opening  501   b  of the through hole  501  and the blue-violet semiconductor laser chip  20  placed on the surface of the wiring electrode  531  exposed in the opening  501   b . Thus, a support base on which the blue-violet semiconductor laser chip  20  is placed can be formed as a different member employing a different material from the Si (100) substrate  510 , and hence the strength of the semiconductor laser apparatus  500  can be further secured. In the manufacturing process, the Si (100) substrate  510  formed with the through hole  501  and the tabular base  550  are bonded to each other through the adhesive resin  551 , whereby the package  90  for placing the blue-violet semiconductor laser chip  20  inside can be easily formed. 
     When wet etching is performed on the Si (100) substrate  510 , the through hole  501  passing through the Si (100) substrate  510  is formed thereby forming the inner surfaces  512 ,  513 ,  514  and  515 , and hence dispersion of the etching depth resulting when wet etching stops in the substrate does not result. Further, the blue-violet semiconductor laser chip  20  placed on the base  550  (copper plate  503 ) can be placed in the recess portion  511  in a state where precision of arrangement is excellent. Thus, in the manufacturing process, deviation of the optical axis of the laser beam and dispersion of the distance from the light-emitting surface to the metal reflective film  561  resulting from an angle (angle in a vertical direction with respect to a cavity direction or a width direction) in which the blue-violet semiconductor laser chip  20  is placed can be effectively inhibited. 
     The blue-violet semiconductor laser chip  20  is placed on the wiring electrode  531  (copper plate  503 ) having excellent thermal conductivity through the submount  40 , and hence heat of the blue-violet semiconductor laser chip  20  can be efficiently radiated through the wiring electrode  531  (copper plate  503 ). 
     The Si (100) substrate  510  having the main surface inclined at about 9.7° with respect to the substantially (100) plane is employed, whereby the four inner surfaces  512  to  515  can be formed simultaneously with wet etching when the through hole  501  is formed in the Si (100) substrate  510  by the wet etching. Consequently, the manufacturing process is simplified, and hence the semiconductor laser apparatus  500  can be efficiently manufactured. 
     The plurality of through holes  501  are simultaneously formed in the Si (100) substrate  510  in a wafer state, whereby the plurality of through holes  501  can be simultaneously formed through a single etching step, and hence the semiconductor laser apparatus  500  can be efficiently manufactured. 
     The sealing glass  560  in a wafer state is bonded to a wafer in which the blue-violet semiconductor laser chip  20  is placed on the bottom surface  516  of each of a plurality of the recess portions  511  (wafer in which the base  550  is bonded to the Si (100) substrate  510 ) by thermocompression bonding, thereby sealing the recess portions  511 . Thus, the plurality of recess portions  511  can be simultaneously hermetically sealed through a step of bonding a single piece of the sealing glass  560 , and hence the semiconductor laser apparatus  500  can be efficiently manufactured. The remaining effects of the fifth embodiment are similar to those of the first embodiment. 
     Sixth Embodiment 
     An optical pickup  600  according to a sixth embodiment of the present invention is now described. The optical pickup  600  is an example of the “optical apparatus” in the present invention. 
     The optical pickup  600  comprises a three-wavelength semiconductor laser apparatus  605 , an optical system  620  adjusting laser beams emitted from the three-wavelength semiconductor laser apparatus  605  and a light detection portion  630  receiving the laser beams, as shown in  FIG. 25 . 
     The three-wavelength semiconductor laser apparatus  605  is mounted with a blue-violet semiconductor laser chip  20  and a two-wavelength semiconductor laser chip  60  having a red semiconductor laser element  50  with a lasing wavelength of about 650 nm and an infrared semiconductor laser element  55  with a lasing wavelength of about 780 nm monolithically formed on a submount  40  in a package  90  adjacent to the blue-violet semiconductor laser chip  20 , as shown in  FIG. 24 . The three-wavelength semiconductor laser apparatus  605  is an example of the “semiconductor laser apparatus” in the present invention, and the red semiconductor laser element  50 , the infrared semiconductor laser element  55  and the two-wavelength semiconductor laser chip  60  are examples of the “semiconductor laser chip” in the present invention. 
     A base  10  is provided with lead frames  11 ,  72 ,  73 ,  74  and  75  made of metal. These lead frames  11  and  72  to  75  are so arranged as to pass through the base  10  from the front side (A 1  side) to the back side (A 2  side) in a state of being isolated from each other by resin mold. Back end regions extending to the outside (A 2  side) of the base  10  each are connected to a driving circuit (not shown). Front end regions  11   a ,  72   a ,  73   a ,  74   a  and  75   a  extending to the front side (A 1  side) of the lead frames  11  and  72  to  75  are exposed from an inner wall portion  10   g  and arranged on a bottom surface of a recess portion  10   b.    
     A first end of a metal wire  91  is bonded to a p-side electrode  21 , and a second end of the metal wire  91  is connected to the front end region  74   a  of the lead frame  74 . A first end of a metal wire  92  is bonded to a p-side electrode  51  formed on an upper surface of the red semiconductor laser element  50 , and a second end of the metal wire  92  is connected to the front end region  73   a  of the lead frame  73 . A first end of a metal wire  93  is bonded to a p-side electrode  56  formed on an upper surface of the infrared semiconductor laser element  55 , and a second end of the metal wire  93  is connected to the front end region  72   a  of the lead frame  72 . An n-side electrode (not shown) formed on a lower surface of the blue-violet semiconductor laser chip  20  and an n-side electrode (not shown) formed on a lower surface of the two-wavelength semiconductor laser chip  60  are electrically connected to the front end region  11   a  of the lead frame  11  through the submount  40 . 
     A first end of a metal wire  94  is bonded to an upper surface of a PD  42 , and a second end of the metal wire  94  is connected to the front end region  75   a  of the lead frame  75 . 
     A cross section of the base  10  is elongated in a width direction (direction B), whereby a base body  10   a  has a maximum width W 61  (W 61 &gt;W 1 ), as compared with the aforementioned semiconductor laser apparatus  100  according to the first embodiment. Therefore, an opening  10   d  in a front portion of the recess portion  10   b  is also elongated in the direction B. The remaining structure of the three-wavelength semiconductor laser apparatus  605  is substantially similar to that of the semiconductor laser apparatus  100  according to the first embodiment, and the structure similar to that of the first embodiment is denoted by the same reference numerals in the figure. 
     In a manufacturing process of the three-wavelength semiconductor laser apparatus  605 , the blue-violet semiconductor laser chip  20  and the two-wavelength semiconductor laser chip  60  are aligned in a lateral direction (direction B in  FIG. 24 ) and bonded through the submount  40 . Thereafter, the respective p-side electrodes  21 ,  51  and  56  of the laser chips  20  and  60  and the upper surface of the PD  42  and the front end regions  72   a ,  73   a ,  74   a  and  75   a  of the lead frames  72 ,  73 ,  74  and  75  are wire-bonded to each other. The remaining manufacturing process is substantially similar to that of the first embodiment. 
     The optical system  620  has a polarizing beam splitter (PBS)  621 , a collimator lens  622 , a beam expander  623 , a λ/4 plate  624 , an objective lens  625 , a cylindrical lens  626  and an optical axis correction device  627 . 
     The PBS  621  totally transmits the laser beams emitted from the three-wavelength semiconductor laser apparatus  605 , and totally reflects the laser beams fed back from an optical disc  635 . The collimator lens  622  converts the laser beams emitted from the three-wavelength semiconductor laser apparatus  605  and transmitted through the PBS  621  to parallel beams. The beam expander  623  is constituted by a concave lens, a convex lens and an actuator (not shown). The actuator has a function of correcting wave surface states of the laser beams emitted from the three-wavelength semiconductor laser apparatus  605  by varying a distance between the concave lens and the convex lens in response to a servo signal from a servo circuit described later. 
     The λ/4 plate  624  converts the linearly polarized laser beams, substantially converted to the parallel beams by the collimator lens  622 , to circularly polarized beams. Further, the λ/4 plate  624  converts the circularly polarized laser beams fed back from the optical disc  635  to linearly polarized beams. A direction of linear polarization in this case is orthogonal to a direction of linear polarization of the laser beams emitted from the three-wavelength semiconductor laser apparatus  605 . Thus, the PBS  621  substantially totally reflects the laser beams fed back from the optical disc  635 . The objective lens  625  converges the laser beams transmitted through the λ/4 plate  624  on a surface (recording layer) of the optical disc  635 . An objective lens actuator (not shown) renders the objective lens  625  movable in a focus direction, a tracking direction and a tilt direction in response to servo signals (a tracking servo signal, a focus servo signal and a tilt servo signal) from the servo circuit described later. 
     The cylindrical lens  626 , the optical axis correction device  627  and the light detection portion  630  are arranged to be along optical axes of the laser beams totally reflected by the PBS  621 . The cylindrical lens  626  provides the incident laser beams with astigmatic action. The optical axis correction device  627  is constituted by a diffraction grating and so arranged that spots of zero-order diffracted beams of blue-violet, red and infrared laser beams transmitted through the cylindrical lens  626  coincide with each other on a detection region of the light detection portion  630  described later. 
     The light detection portion  630  outputs a playback signal on the basis of intensity distribution of the received laser beams. The light detection portion  630  has a detection region of a prescribed pattern, to obtain a focus error signal, a tracking error signal and a tilt error signal along with the playback signal. Thus, the optical pickup  600  comprising the three-wavelength semiconductor laser apparatus  605  is formed. 
     In this optical pickup  600 , the three-wavelength semiconductor laser apparatus  605  can independently emit blue-violet, red and infrared laser beams from the blue-violet semiconductor laser chip  20 , the red semiconductor laser element  50  and the infrared semiconductor laser element  55  by independently applying voltages between the lead frame  11  and the respective lead frames  72  to  74 . The laser beams emitted from the three-wavelength semiconductor laser apparatus  605  are adjusted by the PBS  621 , the collimator lens  622 , the beam expander  623 , the λ/4 plate  624 , the objective lens  625 , the cylindrical lens  626  and the optical axis correction device  627  as described above, and thereafter applied onto the detection region of the light detection portion  630 . 
     When data recorded in the optical disc  635  is play backed, the laser beams emitted from the blue-violet semiconductor laser chip  20 , the red semiconductor laser element  50  and the infrared semiconductor laser element  55  are controlled to have constant power and applied to the recording layer of the optical disc  635 , so that the playback signal outputted from the light detection portion  630  can be obtained. The actuator of the beam expander  623  and the objective lens actuator driving the objective lens  625  can be feedback-controlled by the focus error signal, the tracking error signal and the tilt error signal simultaneously outputted. 
     When data is recorded in the optical disc  635 , the laser beams emitted from the blue-violet semiconductor laser chip  20  and the red semiconductor laser element  50  (infrared semiconductor laser element  55 ) are controlled in power and applied to the optical disc  635 , on the basis of the data to be recorded. Thus, the data can be recorded in the recording layer of the optical disc  635 . Similarly to the above, the actuator of the beam expander  623  and the objective lens actuator driving the objective lens  625  can be feedback-controlled by the focus error signal, the tracking error signal and the tilt error signal outputted from the light detection portion  630 . 
     Thus, the data can be recorded in or played back from the optical disc  635  with the optical pickup  600  comprising the three-wavelength semiconductor laser apparatus  605 . 
     The optical pickup  600  comprises the three-wavelength semiconductor laser apparatus  605 . In other words, the blue-violet semiconductor laser chip  20  and the two-wavelength semiconductor laser chip  60  are reliably sealed in the package  90 . Thus, the reliable optical pickup  600  having the semiconductor laser chips hard to deteriorate, capable of enduring the use for a long time can be obtained. The effects of the three-wavelength semiconductor laser apparatus  605  are similar to those of the semiconductor laser apparatus  100  according to the first embodiment. 
     Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims. 
     For example, while the surfaces of the lead frames arranged in the sealed space of the base are also covered with the covering agent  16  in each of the first, second and fourth embodiments, the present invention is not restricted to this, but the covering agent  16  may be applied onto only the surface of the base (resin material) other than the lead frames (metal portions). 
     While the sealant  15  is applied onto the substantially entire back surface  45   c  of the sealing member  45  in the aforementioned second embodiment, the present invention is not restricted to this, but the sealant  15  may not be applied onto the back surface  45   c  of the sealing member  45  located in the sealed space of the package  90  so that the surface of the nickel silver sheet may be exposed in the sealed space, similarly to the modification of the first embodiment. 
     While the gas absorbent  49  is not provided in the package  90  in each of the aforementioned second to fifth embodiments, the present invention is not restricted to this, but the gas absorbent  49  may be provided, similarly to the aforementioned first embodiment. In this case, silica gel may be employed as the gas absorbent  49 , or synthetic zeolite, calcium oxide-based absorbent material, activated charcoal or the like other than silica gel, for example, may be employed as the gas absorbent  49 . Synthetic zeolite in the form of a pellet (a cylindrical shape) may be cut in a prescribed size and fixed in the sealed space of the package  90 . 
     While the sealant  15  is applied to the periphery of the hole (window portion) of the sealing member, and thereafter the light transmission portion  35  is thermocompression bonded in the manufacturing process of each of the aforementioned first, third and fourth embodiments, the present invention is not restricted to this. For example, EVOH resin previously formed in the form of a thin film may be cut and placed on the periphery of the hole  34 , and thereafter the light transmission portion  35  may be thermocompression bonded. 
     While the “sealing member” in the present invention is made of aluminum foil in the aforementioned first embodiment, in the present invention, the sealing member may be formed by employing Cu foil, Cu alloy foil such as nickel silver, Sn foil, stainless steel foil or the like as metal foil other than aluminum foil, for example. 
     While the base  410  and the cap  430  are made of polyamide resin in the aforementioned fourth embodiment, the base  410  and the cap  430  may be made of resin with low water vapor permeability other than polyamide resin, and permeation of moisture can be sufficiently inhibited. 
     While the base is sealed in a state where the sealant  15  made of EVOH resin is formed on the back surface of the “sealing member” in the present invention made of aluminum foil in the aforementioned first embodiment, in the present invention, the sealing member may be formed by employing epoxy resin or the like other than metal, for example and mounted on the base through the sealant  15  arranged on the back surface. If the aforementioned resin material is employed as the sealing member, EVOH resin (sealant  15 ) having excellent gas barrier properties can more effectively inhibit low molecular siloxane, volatile organic gas or the like from entering the package  90 . 
     While the “sealing member” in the present invention is made of a nickel silver (Cu alloy) sheet in the aforementioned second embodiment, in the present invention, the sealing member may be formed by employing an aluminum plate, a Cu plate, an alloy plate such as Sn, Ni and Mg, a stainless steel plate or the like other than the nickel silver sheet, for example. 
     Further, multilayer metal oxide films (dielectric films) of Al 2 O 3 , SiO 2 , ZrO 2  and the like may be formed as gas barrier layers on surfaces of the light transmission portion (sealing glass) also in each of the aforementioned third to fifth embodiments. Alternatively, metal films of Al, Ni, Pt, Au or the like may be formed. Metal films may be formed on surfaces of a lead frame resin member in each of the first, second and sixth embodiments. 
     While the sealant  15  is applied onto one surface of the sealing member in a state where the sealing member is heated to about 220° C. in the manufacturing process of each of the aforementioned first, second, fourth and fifth embodiments, in the present invention, the sealing member may be heated to remove solvent after a mixture of the solvent and EVOH resin prepared by dissolving the EVOH resin in the solvent is applied to the sealing member. 
     While the base body  10   a  is made of polyamide resin (PA) in each of the aforementioned first and second embodiments, in the present invention, the base may be made of epoxy resin, polyphenylene sulfide resin (PPS), a liquid crystal polymer (LCP) or the like. At this time, the base body  10   a  can be molded in a state of a mixture obtained by introducing a gas absorbent into a resin material at a prescribed ratio. The gas absorbent is preferably prepared from a granular absorbent having a particle diameter of at least several 10 μm and not more than several 100 μm. 
     While the depth of the recess portion  10   b  of the base  10  is about half the thickness t 1  of the base body  10   a  in each of the aforementioned first and second embodiments, the present invention is not restricted to this, but the depth of the recess portion  10   b  may be deeper or shallower than the thickness t 1 / 2 , for example. 
     While the side surfaces (the outer surface and the inner surface) of the sealant  15  for bonding the cap  330  and the light transmission portion  35  to each other are covered with the covering agent  18  in each of the aforementioned third embodiment and the modification thereof, the present invention is not restricted to this, but side surfaces of the sealant  15  for bonding the sealing member and the window member in another embodiment to each other may be covered with this covering agent  18 . An oxide film of Al 2 O 3 , SiO 2 , ZrO 2  or the like or a metal thin film of Al, Pt, Ag, Au, Pd, Ni or the like other than the resin may be employed as the covering agent  18 , and the resin may contain a high proportion of binders of an inorganic material such as SiO 2 . In addition to the side surfaces of the sealant  15 , resin surfaces of PA, PPS, LCP, etc. may be covered with the covering agent  18 , and moisture can be inhibited from penetrating into the PA, PPS and LCP. 
     While the optical pickup  600  comprising the “semiconductor laser apparatus” in the present invention has been shown in the aforementioned sixth embodiment, the present invention is not restricted to this, but the semiconductor laser apparatus in the present invention may be applied to an optical disc apparatus performing record in and playback of an optical disc such as a CD, a DVD or a BD. Further, an RGB three-wavelength semiconductor laser apparatus as the “semiconductor laser apparatus” in the present invention may be constituted by red, green and blue semiconductor laser chips, and this RGB three-wavelength semiconductor laser apparatus may be applied to an optical apparatus such as a projector.