Patent Publication Number: US-2012033702-A1

Title: Semiconductor laser apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor laser apparatus. 
     2. Description of the Background Art 
     With recent enhancements of the performance of personal computers and multimedia equipment, the amount of information to be processed has markedly increased. The increased amount of information has led to the development of optical recording mediums and their drives which can handle increased capacity and increased speed of information processing. 
     Semiconductor laser apparatuses are used, in particular, in optical recording medium drives which are capable of reads and writes from and to optical recording mediums, such as a CD-R (Compact Disk-Recordable) drive, an MO (Magneto-optical) drive, or a DVD (Digital Versatile Disk) drive. 
     In a light-emission device disclosed in JP 2002-230502 A, for example, a plurality of pins having electrical conductivity are provided on a support base which supports semiconductor laser devices. The plurality of pins, respectively, are connected to an n-side electrode and a p-side electrode in each of the semiconductor laser devices through wires. With this structure, when a voltage is applied between the n-side electrode and the p-side electrode in each of the semiconductor laser devices, a current is injected in an active layer which is formed in each semiconductor laser device, causing recombination of holes and electrons to emit light. 
     In the above-described light emitting device, however, a red semiconductor laser device that emits a red beam light and an infrared semiconductor laser device that emits an infrared beam light have a common n-side electrode, while the red semiconductor laser device and a blue-violet semiconductor laser device that emits a blue-violet beam of light have a common p-side electrode and a common n-side electrode. This makes it difficult to apply an arbitrary voltage to each of the red semiconductor laser device, infrared semiconductor laser device, and blue-violet semiconductor laser device independently. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a semiconductor laser apparatus that comprises a plurality of semiconductor laser devices, in which the electrodes of each of the plurality of semiconductor laser devices can receive voltage independently. 
     A semiconductor laser apparatus according to one aspect of the present invention comprises: an electrically conducting package; an electrically conducting mount provided on the package; first, second, and third terminals that are provided on the package and isolated from the package; a fourth terminal that is provided on the package and electrically connected to the mount; and first, second, and third semiconductor laser devices that are provided on the mount, each having a first electrode, wherein the first terminal and the second terminal are arranged along a first direction, the third terminal and the fourth terminal are arranged along a second direction that crosses with the first direction, the first, second, and third semiconductor laser devices are arranged such that the first electrode of the first semiconductor laser device is located closer to the first terminal than the first electrodes of the second and third semiconductor laser devices, the first electrode of the second semiconductor laser device is located closer to the second terminal than the first electrodes of the first and third semiconductor laser devices, and at least a portion of the first electrode of the third semiconductor laser device is located between the first electrode of the first semiconductor laser device and the first electrode of the second semiconductor laser device in the first direction, the first terminal and the first electrode of the first semiconductor laser device are connected through a first wire, the second terminal and the first electrode of the second semiconductor laser device are connected through a second wire, and the third terminal and the first electrode of the third semiconductor laser device are connected through a third wire, and the third semiconductor laser device further has a second electrode that is electrically connected to the mount. 
     In the semiconductor laser apparatus, the first terminal and the first electrode of the first semiconductor laser device are connected through the first wire, the second terminal and the first electrode of the second semiconductor laser device are connected through the second wire, and the third terminal and the first electrode of the third semiconductor laser device are connected through the third wire. This allows each of the first semiconductor laser device, second semiconductor laser device, and third semiconductor laser device to be driven independently. 
     Moreover, the first electrode of the first semiconductor laser device is located closer to the first terminal than the first electrodes of the second and third semiconductor laser devices, so that the first electrode of the first semiconductor laser device and the first terminal can be connected simply and easily through the first wire. The first electrode of the second semiconductor laser device is located closer to the second terminal than the first electrodes of the first and third semiconductor laser devices, so that the first electrode of the second semiconductor laser device and the second terminal can be connected simply and easily through the second wire. The at least a portion of the first electrode of the third semiconductor laser device is located between the first electrode of the first semiconductor laser device and the first electrode of the second semiconductor laser device in the first direction, so that the first electrode of the third semiconductor laser device and the third terminal can be connected simply and easily through the third wire. 
     It is preferred that the first semiconductor laser device and the second semiconductor laser device are provided on the third semiconductor laser device. This allows spacing among the laser beams emitted from the respective first, second, and third semiconductor laser devices to be narrower. 
     The third semiconductor laser device may have a ridge portion formed on the first electrode side of the third semiconductor laser device and an insulating film formed on side surfaces of the ridge portion, the ridge portion being provided between the first semiconductor laser device and the second semiconductor laser device. In this case, the first electrode of the third semiconductor laser device and the third terminal can be connected simply and easily through the third wire. 
     It is preferred that a first connection position of the first wire and the first electrode of the first semiconductor laser device, a third connection position of the third wire and the first electrode of the third semiconductor laser device, and a second connection position of the second wire and the first electrode of the second semiconductor laser device are arranged in this order from the first terminal side to the second terminal side in the first direction. This prevents the first, second, and third wires from crossing one another. 
     The third connection position may be set on an opposite side of a laser beam emitting side of each of the first, second, and third semiconductor laser devices relative to at least one of the first and second connection positions. This decreases the inductance component of the third wire, thereby driving the third semiconductor laser device at high speed. 
     The first, second, and third terminals may extend from one side to another side along a third direction that crosses with the first direction and the second direction, the first, second, and third semiconductor laser devices being arranged to emit main laser beams toward the other side along the third direction, each of the first and second semiconductor laser devices further having a second electrode, and the second electrode of the first semiconductor laser device being electrically connected to the mount through a fourth wire in a position on the laser beam emitting side of the first semiconductor laser device relative to the first connection position. In this case, the second electrode of the first semiconductor laser device and the second electrode of the third semiconductor laser device can be commonly connected to the mount through the fourth wire. 
     The second electrode of the second semiconductor laser device may be electrically connected to the mount through a fifth wire in a position on the laser beam emitting side of the second semiconductor laser device relative to the second connection position. In this case, the second electrode of the second semiconductor laser device and the second electrode of the third semiconductor laser device can be commonly connected to the mount through the fifth wire. 
     A semiconductor laser apparatus according to another aspect of the present invention comprises: an electrically conducting package; an electrically conducting mount provided on the package; first, second, and third terminals that are provided on the package and isolated from the package; a fourth terminal that is provided on the package and electrically connected to the mount; and first, second, and third semiconductor laser devices that are provided on the mount, each having a first electrode, wherein the first terminal and the second terminal are arranged along a first direction, the third terminal and the fourth terminal are arranged along a second direction that crosses with the first direction, the first, second, and third semiconductor laser devices are arranged such that the first electrode of the first semiconductor laser device is located closer to the first terminal than the first electrodes of the second and third semiconductor laser devices, and the first electrode of the second semiconductor laser device is located closer to the second terminal than the first electrodes of the first and third semiconductor laser devices, the semiconductor laser apparatus further comprises a submount between the first electrode of the third semiconductor laser device and the mount, the first electrode of the third semiconductor laser device is formed on the submount to protrude from the third semiconductor laser device, the first terminal and the first electrode of the first semiconductor laser device are connected through a first wire, the second terminal and the first electrode of the second semiconductor laser device are connected through a second wire, and the third terminal and the first electrode of the third semiconductor laser device are connected through a third wire on the submount, and the second electrode of the third semiconductor laser device is electrically connected to the mount. 
     In the semiconductor laser apparatus, the first terminal and the first electrode of the first semiconductor laser device are connected through the first wire, the second terminal and the first electrode of the second semiconductor laser device are connected through the second wire, and the third terminal and the first electrode of the third semiconductor laser device are connected through the third wire. This allows each of the first semiconductor laser device, second semiconductor laser device, and third semiconductor laser device to be driven independently. 
     Moreover, the first electrode of the first semiconductor laser device is located closer to the first terminal than the first electrodes of the second and third semiconductor laser devices, so that the first electrode of the first semiconductor laser device and the first terminal can be connected simply and easily through the first wire. The first electrode of the second semiconductor laser device is located closer to the second terminal than the first electrodes of the first and third semiconductor laser devices, so that the first electrode of the second semiconductor laser device and the second terminal can be connected simply and easily through the second wire. The first electrode of the third semiconductor laser device is formed on the submount to protrude from the third semiconductor laser device, so that the first electrode of the third semiconductor laser device and the third terminal can be connected on the submount simply and easily through the third wire. 
     It is preferred that at least a portion of the first electrode of the third semiconductor laser device is located closer to the third terminal than the first electrodes of the first and second semiconductor laser devices. In this manner, the first electrode of the third semiconductor laser device and the third terminal can be connected more simply and easily through the third wire. 
     It is preferred that the first semiconductor laser device and the second semiconductor laser device are provided on the third semiconductor laser device. This allows spacing among the laser beams emitted from the respective first, second, and third semiconductor laser devices to be narrower. 
     It is preferred that a first connection position of the first wire and the first electrode of the first semiconductor laser device, a third connection position of the third wire and the first electrode of the third semiconductor laser device, and a second connection position of the second wire and the first electrode of the second semiconductor laser device are arranged in this order from the first terminal side to the second terminal side in the first direction. This prevents the first, second, and third wires from crossing one another. 
     The third connection position may be set on an opposite side of a laser beam emitting side of each of the first, second, and third semiconductor laser devices relative to at least one of the first and second connection positions. This decreases the inductance component of the third wire, thereby driving the third semiconductor laser device at high speed. 
     The first, second, and third terminals may extend from one side to another side along a third direction that crosses with the first direction and the second direction, the first, second, and third semiconductor laser devices being arranged to emit main laser beams toward the other side along the third direction, each of the first and second semiconductor laser devices further having a second electrode, the second electrodes of the first, second, and third semiconductor laser devices being electrically connected with one another, and the second electrode of the third semiconductor laser device being electrically connected to the mount through a fourth wire in a position on the laser beam emitting side of the first semiconductor laser device relative to the first connection position. 
     In this case, the second electrodes of the first, second, and third semiconductor laser devices are electrically connected with one another, so that the second electrodes of the first, second, and third semiconductor laser devices can be commonly connected to the mount through the fourth wire. 
     A semiconductor laser apparatus according to still another aspect of the present invention comprises: an electrically conducting package; an electrically conducting mount provided on the package; first, second, and third terminals that are provided on the package and isolated from the package; a fourth terminal that is provided on the package and electrically connected to the mount; and first, second, and third semiconductor laser devices that are provided on the mount, each having a first electrode, wherein the first terminal and the second terminal are arranged along a first direction, the third terminal and the fourth terminal are arranged along a second direction that crosses with the first direction, an emission portion of the first semiconductor laser device, an emission portion of the third semiconductor laser device, and an emission portion of the second semiconductor laser device are arranged in this order from the first terminal side to the second terminal side along the first direction, the first electrode of the third semiconductor laser device extends in the first direction closer to the second terminal than a side surface of the second semiconductor laser device on the second terminal side, the first terminal and the first electrode of the first semiconductor laser device are connected through a first wire, the second terminal and the first electrode of the third semiconductor laser device are connected through a third wire, and the third terminal and the first electrode of the second semiconductor laser device are connected through a second wire, and the third semiconductor laser device emits a laser beam with a wavelength shorter than the wavelengths of laser beams emitted from the first and second semiconductor laser devices, and further has an a second electrode which is electrically connected to the mount. 
     In the semiconductor laser apparatus, the emission portion of the third semiconductor laser that emits a laser beam with a wavelength shorter than the wavelengths of laser beams emitted from the first and second semiconductor laser devices is located between the emission portion of the first semiconductor laser device and the emission portion of the second semiconductor laser device in the first direction. Thus, the third semiconductor laser device is positioned on the central portion of the package. This allows for improved light utilization efficiency through the emission portion of the third semiconductor laser device when converging the light beam through a lens, for example. 
     Moreover, the first electrode of the third semiconductor laser device extends in the first direction closer to the second terminal than the side surface of the second semiconductor laser device on the second terminal side. In this manner, the length of the third wire can be shorter which connects the second terminal with the first electrode of the third semiconductor laser device that emits a wavelength shorter than those of the first and second semiconductor laser devices. This decreases the inductance component of the third wire, thereby driving the third semiconductor laser device at high speed. 
     In addition, the first electrode of the first semiconductor laser device and the first terminal can be connected simply and easily through the first wire. The first electrode of the third semiconductor laser device and the second terminal can be connected simply and easily through the third wire. The first electrode of the second semiconductor laser device and the third terminal can be connected simply and easily through the second wire. 
     The first, second, and third terminals may extend from one side to another side along a third direction that crosses with the first direction and the second direction, the first, second, and third semiconductor laser devices being arranged to emit main laser beams toward the other side along the third direction, each of the first and second semiconductor laser devices further having a second electrode, and the second electrode of the first semiconductor laser device being electrically connected to the mount through a fourth wire in a position on the laser beam emitting side of the first semiconductor laser device relative to a first connection position of the first wire and the first electrode of the first semiconductor laser device. 
     In this case, the second electrode of the first semiconductor laser device and the second electrode of the third semiconductor laser device can be commonly connected to the mount through the fourth wire. 
     The second electrode of the second semiconductor laser device may be electrically connected to the mount through a fifth wire in a position on the laser beam emitting side of the second semiconductor laser device relative to a second connection position of the second wire and the first electrode of the second semiconductor laser device. 
     In this case, the second electrode of the second semiconductor laser device and the second electrode of the third semiconductor laser device can be commonly connected to the mount through the fifth wire. 
     The second connection position may be set on an opposite side of a laser beam emitting side of each of the first, second, and third semiconductor laser devices relative to at least one of the first connection position and a third connection position of the third wire and the first electrode of the third semiconductor laser device. This decreases the inductance component of the third wire, thereby driving the third semiconductor laser device at high speed. 
     It is preferred that when the first, second, and third semiconductor laser devices are viewed in the second direction, the first, second, third and fourth wires are not crossing one another. In this manner, wiring of the electrodes, terminals, and mount can be made simply and easily. 
     The third semiconductor layer device may include an active laser composed of a nitride-based semiconductor. In this case, a blue-violet beam of light is emitted from the active layer of the third semiconductor laser device. 
     The length of the third terminal may be shorter than the length of each of the first and second terminals, the first, second, and third terminals extending from one side to another side along a third direction that crosses with the first direction and the second direction, the first, second, and third semiconductor laser devices being arranged to emit main laser beams toward the other side along the third direction, the first, second, and third semiconductor laser devices being arranged between the first terminal and the second terminal in the first direction, and the length of the third terminal being set such that the third terminal does not overlap with a facet opposite to a laser beam emitting side of each of the first, second, and third semiconductor laser devices. This allows the first, second, and third semiconductor laser devices to be easily mounted on the mount without being prevented by the third terminal. 
     A semiconductor laser apparatus according to yet another aspect of the present invention comprises: an electrically conducting package; an electrically conducting mount that is provided on the package; first and second terminals that are provided on the package and isolated from the package; and first and second semiconductor laser devices that are provided on the mount, each having a first electrode and a second electrode, wherein the first semiconductor laser device is provided on the second semiconductor laser device, the first terminal and the second terminal are arranged along a first direction, the first terminal and the first electrode of the first semiconductor laser device are connected through a first wire, while the second terminal and the first electrode of the second semiconductor laser device are connected through a second wire, and at least one of the second electrodes of the first and second semiconductor laser devices is electrically connected to the mount through a wire on the mount side. 
     In the semiconductor laser apparatus, the first terminal and the first electrode of the first semiconductor laser device are connected through the first wire, while the second terminal and the first electrode of the second semiconductor laser device are connected through the second wire. This allows each of the first semiconductor laser device and second semiconductor laser device to be driven independently. 
     It is preferred that the first semiconductor laser device is located closer to the first terminal than the second terminal on the second semiconductor laser device. This allows the first electrode of the first semiconductor laser device and the first terminal to be connected simply and easily through the first wire, while preventing the first wire and the second wire from crossing each other. 
     The second semiconductor laser device may include an active layer composed of a nitride-based semiconductor. In this case, a blue-violet beam of light is emitted from the active layer of the second semiconductor laser device. 
     At least one of the second electrodes of the first and second semiconductor laser devices may be electrically connected to the mount through the wire on the mount side in a position on a laser beam emitting side of the first semiconductor laser device, relative to a first connection position of the first wire and the first electrode of the first semiconductor laser device or a second connection position of the second wire and the first electrode of the second semiconductor laser device. This prevents the wire on the mount side from crossing each of the first wire and second wire. 
     In the first to third inventions, each of the first semiconductor laser device, second semiconductor laser device, and third semiconductor laser device can be driven independently, while the first electrode of each of the first to third semiconductor laser devices can be connected with each of the terminals through a wire simply and easily. 
     In the fourth embodiment, each of the first semiconductor laser device and second semiconductor laser device can be driven independently, while the first electrode of each of the first and second semiconductor laser devices can be connected with each of the terminals through a wire simply and easily. 
     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 a schematic cross-section showing an example of a semiconductor laser apparatus according to a first embodiment; 
         FIG. 2  ( a ) is a schematic cross-section showing the semiconductor laser apparatus of  FIG. 1  when assembled on a mount; 
         FIG. 2  ( b ) is a top view of the semiconductor laser apparatus of  FIG. 1  when assembled on the mount; 
         FIG. 3  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a second embodiment; 
         FIG. 4  ( a ) is a schematic cross-section showing the semiconductor laser apparatus of  FIG. 3  when assembled on a mount; 
         FIG. 4  ( b ) is a top view showing the semiconductor laser apparatus of  FIG. 3  when assembled on the mount; 
         FIG. 5  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a third embodiment; 
         FIG. 6  ( a ) is a schematic cross-section showing the semiconductor laser apparatus of  FIG. 5  when assembled on a mount; 
         FIG. 6  ( b ) is a top view of the semiconductor laser apparatus of  FIG. 5  when assembled on the mount; 
         FIG. 7  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a fourth embodiment; 
         FIG. 8  ( a ) is a schematic cross-section showing the semiconductor laser apparatus of  FIG. 7  when assembled on a mount; 
         FIG. 8  ( b ) is a top view of the semiconductor laser apparatus of  FIG. 7  when assembled on the mount; and 
         FIG. 9  is a schematic cross-section showing a semiconductor laser apparatus according to a fifth embodiment when assembled on a mount. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A semiconductor laser apparatus according to an embodiment of the present invention will now be described with reference to the drawings. 
     First Embodiment 
       FIG. 1  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a first embodiment. 
     The semiconductor laser apparatus  100  according to the embodiment comprises a semiconductor laser apparatus (hereinafter referred to as a red semiconductor laser device)  1  that emits a laser beam with a wavelength of approximately 650 nm, a semiconductor laser apparatus (hereinafter referred to as an infrared semiconductor laser device)  2  that emits a laser beam with a wavelength of approximately 780 nm, and a semiconductor laser apparatus (hereinafter referred to as a blue-violet semiconductor laser device)  3  that emits a laser beam with a wavelength of approximately 400 nm. The blue-violet semiconductor laser device  3  includes an active layer composed of a nitride-based semiconductor (not shown). 
     In the embodiment, the blue-violet semiconductor laser device  3  is fabricated by forming semiconductor layers on the GaN substrate. The red semiconductor laser device  1  and the infrared semiconductor laser device  2  are fabricated by forming semiconductor layers on the GaAs substrate. 
     As shown in  FIG. 1 , the blue-violet semiconductor laser device  3  has a stripe-like ridge portion Ri on an upper surface. An insulating film  4  is formed on both sides of the ridge portion Ri in the blue-violet semiconductor laser device  3 , and a p-electrode  32  is formed to cover an upper surface of the ridge portion Ri. An n-electrode  35  is formed on a lower surface of the blue-violet semiconductor laser device  3 . In the blue-violet semiconductor laser device  3 , a p-n junction surface  30  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     The red semiconductor laser device  1  has an n-electrode  13  formed on an upper surface and a p-electrode  12  formed on a lower surface. In the red semiconductor laser device  1 , a p-n junction surface  10  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     The infrared semiconductor laser device  2  has an n-electrode  23  formed on an upper surface and a p-electrode  22  formed on a lower surface. In the infrared semiconductor laser device  2 , a p-n junction surface  20  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     On the insulating film  4  of the blue-violet semiconductor laser device  3 , p-type pad electrodes  12   a ,  22   a  are formed at a distance from the p-type electrode  32 . 
     Solder films H are formed on upper surfaces of the p-type pad electrodes  12   a ,  22   a , respectively. In the red semiconductor laser device  1 , the p-electrode  12  is joined to the p-type pad electrode  12   a  with the solder film H therebetween. In the infrared semiconductor laser device  2 , the p-electrode  22  is joined to the p-type pad electrode  22   a  with the solder film H therebetween. 
     This allows for an electrical connection between the p-electrode  12  and the p-type pad electrode  12   a  in the red semiconductor laser device  1 , and an electrical connection between the p-electrode  22  and the p-type pad electrode  22   a  in the infrared semiconductor laser device  2 . 
     In  FIG. 1 , the arrows X, Y, Z indicate three directions, X-direction, Y-direction, and Z-direction, which are orthogonal to one another. The X- and Y-directions are in parallel with the p-n junction surfaces  30 ,  10 ,  20  in the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2 . The Z-direction is vertical to the p-n junction surfaces  30 ,  10 ,  20  in the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2 . 
     The red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  are arranged to emit main laser beams toward one side along the X-direction. 
     When a voltage is applied between the p-electrode  32  and the n-electrode  35  in the blue-violet semiconductor laser device  3 , a laser beam with a wavelength of approximately 400 nm is emitted in the X-direction from a region  31  (hereinafter referred to as a blue-violet-beam-emission point) below the ridge portion Ri in the p-n junction surface  30 . 
     When a voltage is applied between the p-electrode  12  and the n-electrode  13  in the red semiconductor laser device  1 , a laser beam with a wavelength of approximately 650 nm is emitted in the X-direction from a prescribed region  11  (hereinafter referred to as a red-beam-emission point) in the p-n junction surface  10 . 
     When a voltage is applied between the p-electrode  22  and the n-electrode  23  in the infrared semiconductor laser device  2 , a laser beam with a wavelength of approximately 780 nm is emitted in the X-direction from a prescribed region  21  (hereinafter referred to as an infrared-beam-emission point) in the p-n junction surface  20 . 
       FIG. 2  ( a ) is a schematic cross-section showing the semiconductor laser apparatus  100  of  FIG. 1  when assembled on a mount.  FIG. 2  ( b ) is a top view of the semiconductor laser apparatus  100  of  FIG. 1  when assembled on the mount. 
     When the semiconductor laser apparatus  100  of  FIG. 1  is used in an optical pick-up, it is mounted on amount  500  which is composed of a conducting metal such as Cu, CuW, or Al. Then, using wires  3 W,  1 Wa,  1 Wb,  2 Wa,  2 Wb, the p-electrodes  32 ,  12   a ,  22   a  and the n-electrodes  13 ,  23  are wired. 
     In this case, the n-electrode  35  is joined to an upper surface of the mount  500 . This allows for an electrical connection between the n-electrode  35  and the mount  500 . 
     The n-electrode  13  in the red semiconductor laser device  1  is electrically connected to the upper surface of the mount  500  through the wire  1 Wb. The n-electrode  23  in the infrared semiconductor laser device  2  is electrically connected to the mount  500  through the wire  2 Wb. 
     This makes the mount  500  a common n-electrode among the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2 , so as to realize a common-cathode wire connection. 
     The mount  500  having the semiconductor laser apparatus  100  mounted thereon is provided on a conducting stem  501 . 
     The stem  501  is provided with a first terminal  1 P, a second terminal  2 P, a third terminal  3 P, and a fourth terminal  4 P. The length of the third terminal  3 P is shorter than the length of each of the first terminal  1 P and the second terminal  2 P. 
     The first terminal  1 P is isolated from the stem  501  by an insulating ring  1 I. The second terminal  2 P is isolated from the stem  501  by an insulating ring  2 I. The third terminal  3 P is isolated from the stem  501  by an insulating ring  3 I. The fourth terminal  4 P, which is provided inside the mount  500 , is electrically conducting to the mount  500 . 
     The first terminal  1 P and the second terminal  2 P are arranged along the Y-direction, while the third terminal  3 P and the fourth terminal  4 P are arranged along the Z-direction that crosses with the Y-direction. The first terminal  1 P, second terminal  2 P, and third terminal  3 P extend from one side to another along the X-direction. 
     The red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  are arranged in the Y-direction between the first terminal  1 P and the second terminal  2 P. 
     The length of the third terminal  3 P is set such that the third terminal  3 P does not overlap with a facet opposite to an emission side of a facet that emits the main laser beam in each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3 . 
     As used herein, the facet that emits the main laser beam refers to a facet whereby a greater amount of light is emitted than the opposite facet (hereinafter referred to as a facet on the emission side). 
     Now, description is made of the positions of the p-type pad electrode  12   a , p-type pad electrode  22   a , and p-electrode  32  in the blue-violet semiconductor laser device  3 , and the positions of the first terminal  1 P, second terminal  2 P, and third terminal  3 P. 
     The red semiconductor laser device  1 , the infrared semiconductor laser device  2 , and the blue-violet semiconductor laser device  3 , respectively, are arranged such that the p-type pad electrode  12   a  is located closer to the first terminal  1 P than the p-type pad electrode  22   a  and the p-electrode  32  in the blue-violet semiconductor laser device  3 , the p-type pad electrode  22   a  is located closer to the second terminal  2 P than the p-type pad electrode  12   a  and the p-electrode  32  in the blue-violet semiconductor laser device  3 , and the p-electrode  32  in the blue-violet semiconductor laser device  3  is located between the p-type pad electrode  12   a  and the p-type pad electrode  22   a  in the Y-direction. 
     Thus, as shown in  FIG. 2  ( b ), the first terminal  1 P and the p-type pad electrode  12   a  are connected through the wire  1 Wa simply and easily. Similarly, the second terminal  2 P and the p-type pad electrode  22   a  are connected through the wire  2 Wa simply and easily, and the third terminal  3 P and the p-electrode  32  in the blue-violet semiconductor laser device  3  are connected through the wire  3 W simply and easily. 
     Note also that when the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  are viewed in the Z-direction, the wires  1 Wa,  2 Wa,  3 W,  1 Wb,  2 Wb are not crossing one another. 
     In the present embodiment as described above, application of voltage between the mount  500  and the wire  3 W enables driving the blue-violet semiconductor laser device  3 . Similarly, application of voltage between the mount  500  and the wire  1 Wa enables driving the red semiconductor laser device  1 , and the application of voltage between the mount  500  and the wire  2 Wa enables driving the infrared semiconductor laser device  2 . 
     In this manner, each of the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2  can be driven independently. 
     In addition, the blue-violet-beam-emission point  31  in the blue-violet semiconductor laser device  3  that emits a laser beam with a wavelength shorter than the wavelengths of the laser beams emitted from the red semiconductor laser device  1  and the infrared semiconductor laser device  2  is located in the Y-direction between the red-beam-emission point  11  in the red semiconductor laser device  1  and the infrared-beam-emission point  21  in the infrared semiconductor laser device  2 . This allows the blue-violet semiconductor laser device  3  to be easily positioned on a lens when the semiconductor laser apparatus  100  is used in an optical device such as an optical pick-up. 
     As a result, the effect of aberration around the periphery of the lens can be decreased, while the light utilization efficiency can be improved in the blue-violet semiconductor laser device  3 . 
     It is also preferred that the connection position of the wire  1 Wa and the p-type pad electrode  12   a  in the red semiconductor laser device  1 , the connection position of the wire  3 W and the p-electrode  32  in the blue-violet semiconductor laser device  3 , and the connection position of the wire  2 Wa and the p-type pad electrode  22   a  in the infrared semiconductor laser device  2  are arranged in this order between the first terminal  1 P and the second terminal  2 P in the Y-direction. This prevents the wires  1 Wa,  2 Wa,  3 W from crossing one another. 
     Further, the length of the third terminal  3 P is shorter than the length of each of the first terminal  1 P and second terminal  2 P. The red semiconductor laser device  1 , the infrared semiconductor laser device  2 , and the blue-violet semiconductor laser device  3  are arranged between the first terminal  1 P and the second terminal  2 P in the Y-direction. Also, the length of the third terminal  3 P is set such that it does not overlap in the X-direction with the facet opposite to the facet on the laser beam emitting side of each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3 . This allows the p-electrode  32  in the blue-violet semiconductor laser device  3  and the third terminal  3 P to be connected simply and easily through the wire  3 W. 
     Furthermore, it is preferred that the connection position of the p-electrode  32  in the blue-violet semiconductor laser device  3  and the third terminal  3 P is set on the opposite side of the laser beam emitting side of each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  relative to at least one of the connection position of the p-type pad electrode  12   a  in the red semiconductor laser device  1  and the first terminal  1 P and the connection position of the p-type pad electrode  22   a  in the infrared semiconductor laser device  2  and the second terminal  2 P. This allows the wire  3 W to be shorter with a smaller inductance component, thereby driving the blue-violet semiconductor laser device  3  at high speed. 
     As shown in  FIG. 2  ( a ), it is preferred that the first terminal  1 P, second terminal  2 P, third terminal  3 P and fourth terminal  4 P are provided substantially concentrically on the stem  501 . This prevents each of the wires that connects each semiconductor laser device and each terminal from crossing one another. 
     Note that the positions in which the red semiconductor laser device  1  and infrared semiconductor laser device  2  are arranged may be reversed. 
     The red semiconductor laser device  1  and infrared semiconductor laser device  2  may each have a monolithic structure. 
     A submount composed of silicon carbide or aluminum nitride may also be provided between the blue-violet semiconductor laser device  3  and the mount  500 . In this manner, dissipation of heat from the blue-violet semiconductor laser device  3  is achieved. 
     Second Embodiment 
       FIG. 3  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a second embodiment.  FIG. 4  ( a ) is a schematic cross-section showing the semiconductor laser apparatus of  FIG. 3  when assembled on a mount.  FIG. 4  ( b ) is a top view showing the semiconductor laser apparatus of  FIG. 3  when assembled on the mount. 
     The semiconductor laser apparatus  200  according to the present embodiment differs from the semiconductor laser apparatus  100  according to the first embodiment as follows. 
     As shown in  FIG. 3 , in the semiconductor laser apparatus  200  according to the embodiment, a p-electrode  32  in a blue-violet semiconductor laser device  3  extends closer to a second terminal  2 P in the Y-direction than a side surface of an infrared semiconductor laser device  2  on the second terminal  2 P side. 
     Moreover, a p-type pad electrode  22   a  is formed on a p-electrode  32  with an insulating film  4   b  therebetween. On top of the p-type pad electrode  22   a  is inserted a solder film H, on which is formed an infrared semiconductor laser device  2 . 
     In addition, as shown in  FIGS. 4  ( a ) and  4  ( b ), the p-type pad electrode  22   a  in the infrared semiconductor laser device  2  and a third terminal  3 P are connected through a wire  2 Wa, while the p-electrode  21  in the blue-violet semiconductor laser device  3  and the second terminal  2 P are connected through a wire  3 W. 
     In the present embodiment as described above, application of voltage between the mount  500  and the wire  3 W enables driving the blue-violet semiconductor laser device  3 . Similarly, application of voltage between the mount  500  and the wire  1 Wa enables driving the red semiconductor laser device  1 , and the application of voltage between the mount  500  and the wire  2 Wa enables driving the infrared semiconductor laser device  2 . 
     In this manner, each of the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2  can be driven independently. 
     Also, the blue-violet-beam-emission point  31  in the blue-violet semiconductor laser device  3  that emits a laser beam with a wavelength shorter than the wavelengths of laser beams emitted from the red semiconductor laser device  1  and the infrared semiconductor laser device  2  is located in the Y-direction between the red-beam-emission point  11  in the red semiconductor laser device  1  and the infrared-beam-emission point  21  in the infrared semiconductor laser device  2 . This allows the blue-violet semiconductor laser device  3  to be easily positioned on a lens when the semiconductor laser apparatus  200  is used in an optical device such as an optical pick-up. 
     As a result, the effect of aberration around the periphery of the lens can be decreased, while the light utilization efficiency can be improved in the blue-violet semiconductor laser device  3 . 
     Moreover, the p-electrode  32  in the blue-violet semiconductor laser device  3  extends in the Y-direction closer to the second terminal  2 P than the side surface of the infrared semiconductor laser device  2  on the second terminal  2 P side, so that the length of the wire  3 W can be shorter which connects the second terminal  2 P and the p-electrode  32  in the blue-violet semiconductor laser device  3  that emits the laser beam with a wavelength shorter than the wavelengths of a laser beam emitted from the red semiconductor laser device  1  and the infrared semiconductor laser device  2 . This decreases the inductance component of the wire  3 W, thereby driving the blue-violet semiconductor laser device  3  at high speed. 
     Further, the p-type pad electrode  12   a  in the red semiconductor laser device  1  and the first terminal  1 P can be connected through the wire  1 Wa simply and easily. Similarly, the p-electrode  32  in the blue-violet semiconductor laser device  3  and the second terminal  2 P can be connected through the wire  3 W simply and easily, and the p-type pad electrode  22   a  in the infrared semiconductor laser device  2  and the third terminal  3 P can be connected through the wire  2 Wa simply and easily. 
     Furthermore, it is preferred that the connection position of the p-type pad electrode  22   a  in the infrared semiconductor laser device  2  and the third terminal  2 P is set on the opposite side of the laser beam emitting side of each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  relative to at least one of the connection position of the p-type pad electrode  12   a  in the red semiconductor laser device  1  and the first terminal  1 P and the connection position of the p-electrode  32  in the blue-violet semiconductor laser device  3  and the second terminal  2 P. This prevents the wires  1 Wa,  2 Wa,  3 W from crossing one another. 
     Note that the positions in which the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  are arranged may also be set symmetrically, with the longitudinal direction of the third terminal  3 P at the center. 
     Note also that each of the red semiconductor laser device  1  and the infrared semiconductor laser device  2  may have a monolithic structure. 
     A submount composed of silicon carbide or aluminum nitride may also be provided between the blue-violet semiconductor laser device  3  and the mount  500 . In this manner, dissipation of heat from the blue-violet semiconductor laser device  3  is achieved. 
     In the foregoing first and second embodiments, the wire  1 Wa corresponds to a first wire, the wire  2 Wa corresponds to a second wire, the wire  3 W corresponds to a third wire, the wire  1 Wb corresponds to a fourth wire, and the wire  2 Wb corresponds to a fifth wire. Also, the wires  1 Wb,  2 Wb in the foregoing first and second embodiments correspond to wires on the mount side. 
     Moreover, in the foregoing first and second embodiments, the Y-direction corresponds to a first direction, the Z-direction corresponds to a second direction, and the X-direction corresponds to a third direction. The stem  501  corresponds to a package, the red semiconductor laser device  1  corresponds to a first semiconductor laser device, the infrared semiconductor laser device  2  corresponds to a second semiconductor laser device, and the blue-violet semiconductor laser device  3  corresponds to a third semiconductor laser device. 
     In addition, in the foregoing first and second embodiments, the p-type pad electrode  12   a  corresponds to one electrode of the first semiconductor laser device, the p-type pad electrode  22   a  corresponds to one electrode of the second semiconductor laser device, and the p-electrode  32  corresponds to one electrode of the third semiconductor laser device. The n-electrode  13  corresponds to another electrode of the first semiconductor laser device, the n-electrode  23  corresponds to another electrode of the second semiconductor laser device, and the n-electrode  35  corresponds to another electrode of the third semiconductor laser device. 
     Third Embodiment 
       FIG. 5  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a third embodiment. 
     As shown in  FIG. 5 , the semiconductor laser apparatus  300  of the present embodiment differs from the semiconductor laser apparatus  100  of the first embodiment in that it does not include the infrared semiconductor laser device  2 , solder film H (except the solder film H in the red semiconductor laser device  1 ), and p-type pad electrode  22   a.    
       FIG. 6  ( a ) is a schematic cross-section showing the semiconductor laser apparatus  300  of  FIG. 5  when assembled on a mount.  FIG. 6  ( b ) is a top view of the semiconductor laser apparatus  300  of  FIG. 5  when assembled on the mount. 
     As shown in  FIGS. 6  ( a ) and  6  ( b ), an optical pick-up which is fabricated by assembling the semiconductor laser apparatus  300  of the present embodiment on the mount  500  differs as follows from the optical pick-up which is fabricated by assembling the semiconductor laser apparatus  100  of the first embodiment on the mount  500 . 
     A photodiode  50  is electrically connected to a stem  501 . The photodiode  50  and the third terminal  3 P are connected through a wire  4 W. Also, the p-electrode  32  in the blue-violet semiconductor laser device  3  and the second terminal  2 P are connected through a wire  3 W. 
     Now, description is made of the positions of the p-type pad electrode  12   a  and the p-electrode  32  in the blue-violet semiconductor laser device  3 , and the positions of the first terminal  1 P, second terminal  2 P, and third terminal  3 P. 
     The red semiconductor laser device  1  and the blue-violet semiconductor laser device  3 , are arranged, respectively, such that the p-type pad electrode  12   a  is located closer to the first terminal  1 P than the p-type electrode  32  in the blue-violet semiconductor laser device  3 , and the p-electrode  32  in the blue-violet semiconductor laser device  3  is located closer to the second terminal  2 P than the p-type pad electrode  12   a.    
     This allows the first terminal  1 P and the p-type pad electrode  12   a  to be connected through the wire  1 Wa simply and easily, while allowing the second terminal  2 P and the p-electrode  32  in the blue-violet semiconductor laser device  3  to be connected through the wire  3 W simply and easily. 
     In addition, when the red semiconductor laser device  1  and the blue-violet semiconductor laser device  3  are viewed in the Z-direction, the wires  1 Wa,  3 W,  1 Wb,  4 W are not crossing one another. 
     In the present embodiment as described above, application of voltage between the mount  500  and the wire  3 W enables driving the blue-violet semiconductor laser device  3 , while application of voltage between the mount  500  and the wire  1 Wa enables driving the red semiconductor laser device  1 . In this manner, each of the blue-violet semiconductor laser device  3  and red semiconductor laser device  1  can be driven independently. 
     It is also preferred that the connection position of the wire  1 Wa and the p-type pad electrode  12   a  in the red semiconductor laser device  1  and the connection position of the wire  3 W and the p-electrode  32  in the blue-violet semiconductor laser device  3  are arranged in this order between the first terminal  1 P and the second terminal  2 P in the Y-direction. This prevents the wires  1 Wa,  3 W from crossing each other. 
     It is preferred that the first terminal  1 P, second terminal  2 P, third terminal  3 P, and fourth terminal  4 P are provided substantially concentrically on the stem  501 , as shown in  FIG. 6  ( a ). This prevents each of the wires that connects each semiconductor laser device and each terminal from crossing one another. 
     A submount composed of silicon carbide or aluminum nitride may also be provided between the blue-violet semiconductor laser device  3  and the mount  500 . In this manner, dissipation of heat from the blue-violet semiconductor laser device  3  is achieved. 
     Note that the red semiconductor laser device  1  may be replaced by an infrared semiconductor laser device. 
     In the foregoing third embodiment, the wire  1 Wa corresponds to a first wire, the wire  3 W corresponds to a second wire, and the wire  1 Wb corresponds to a wire on the mount side. The Y-direction corresponds to a first direction, the Z-direction corresponds to a second direction, and the X-direction corresponds to a third direction. The stem  501  corresponds to a package, the red semiconductor laser device  1  corresponds to a first semiconductor laser device, and the blue-violet semiconductor laser device  3  corresponds to a second semiconductor laser device. 
     In the foregoing third embodiment, the p-type pad electrode  12   a  corresponds to one electrode of the first semiconductor laser device, and the p-electrode  32  corresponds to one electrode of the second semiconductor laser device. The n-electrode  13  corresponds to another electrode of the first semiconductor laser device, and the n-electrode  35  corresponds to another electrode of the second semiconductor laser device. 
     Fourth Embodiment 
       FIG. 7  is a schematic cross-section showing an example of a semiconductor laser apparatus according to a fourth embodiment. 
     As shown in  FIG. 7 , the semiconductor laser apparatus  400  of the present embodiment differs from the semiconductor laser apparatus  100  of the first embodiment as follows. 
     A p-electrode  32  is formed to cover the insulating film  4  which is formed on an upper surface and both sides of a ridge portion Ri. Thus, the p-type pad electrodes  12   a ,  22   a  are not provided in the embodiment. 
     Then, on both sides of the p-electrode  32 , a red semiconductor laser device  1  and an infrared semiconductor laser device  2 , respectively, are formed with solder films H therebetween. 
     In this manner, the p-electrode  12  in the red semiconductor laser device  1 , the p-electrode  22  in the infrared semiconductor laser device  2 , and the p-electrode  32  in the blue-violet semiconductor laser device  3  are electrically connected in the semiconductor laser apparatus  400  of the embodiment 
     An insulative submount  60  is provided between the above-mentioned blue-violet semiconductor laser device  3  and a mount  500 . 
     Note that a conductive adhesive is applied to each of the electrode on the rear surface of the blue-violet semiconductor laser device  3  and a surface of the insulative submount  60 , and then the blue-violet semiconductor laser device  3  and the insulative submount  60  are bonded by laminating them with the conductive adhesive. In this embodiment, the electrode on the rear surface of the blue-violet semiconductor laser device  3  and the conductive adhesive are the n-electrode  35 . 
     As described above, the n-electrode  35  is formed such that its ends protrude outwardly from the blue-violet semiconductor laser device  3  when the insulative submount  60  is laminated with the n-electrode  35 . 
       FIG. 8  ( a ) is a schematic cross-section showing the semiconductor laser apparatus  400  of  FIG. 7  when assembled on a mount.  FIG. 8  ( b ) is a top view of the semiconductor laser apparatus  400  of  FIG. 7  when assembled on the mount. 
     As shown in  FIGS. 8  ( a ) and  8  ( b ), an optical pick-up which is fabricated by assembling the semiconductor laser apparatus  400  of the present embodiment on the mount  500  differs as follows from the optical pick-up which is fabricated by assembling the semiconductor laser apparatus  100  of the first embodiment on the mount  500 . 
     As described above, in the blue-violet semiconductor laser device  3 , an insulative submount  60  is provided between an n-electrode  35  and the mount  500 . Thus, the n-electrode  35  and the mount  500  are isolated by the insulative submount  60 . 
     Also, the n-electrode  13  in the red semiconductor laser device  1  and the first terminal  1 P are connected through the wire  1 Wa, then-electrode  23  in the infrared semiconductor laser device  2  and the second terminal  2 P are connected through the wire  2 Wa, and the n-electrode  35  in the blue-violet semiconductor laser device  3  and the third terminal  3 P are connected through the wire  3 W. 
     Further, the p-electrode  32  in the blue-violet semiconductor laser device  3  and the mount  500  are connected through the wire  1 Wb. The wire  1 Wb corresponds to a wire on the mount side. 
     With the above-described structure, when the red semiconductor laser device  1 , the infrared semiconductor laser device  2 , and the blue-violet semiconductor laser device  3  are viewed in the Z-direction, the wires  1 Wa,  2 Wa,  3 W,  1 Wb are not crossing one another. 
     In the present embodiment as described above, application of voltage between the mount  500  and the wire  3 W enables driving the blue-violet semiconductor laser device  3 . Similarly, application of voltage between the mount  500  and the wire  1 Wa enables driving the red semiconductor laser device  1 , and application of voltage between the mount  500  and the wire  2 Wa enables driving the infrared semiconductor laser device  2 . 
     In this manner, each of the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2  can be driven independently. 
     Moreover, the blue-violet-beam-emission point  31  in the blue-violet semiconductor laser device  3  that emits a laser beam with a wavelength shorter than the wavelengths of the laser beam from the red semiconductor laser device  1  and the infrared semiconductor laser device  2  is located in the Y-direction between the red-beam-emission point  11  in the red semiconductor laser device  1  and the infrared-beam-emission point  21  in the infrared semiconductor laser device  2 . This allows the blue-violet semiconductor laser device  3  to be easily positioned on a lens when the semiconductor laser apparatus  400  is used in an optical device such as an optical pick-up. 
     As a result, the effect of aberration around the periphery of the lens can be decreased, while the light utilization efficiency can be improved in the blue-violet semiconductor laser device  3 . 
     In addition, it is preferred that the connection position of the wire  1 Wa and the n-electrode  13  in the red semiconductor laser device  1 , the connection position of the wire  3 W and the n-electrode  35  in the blue-violet semiconductor laser device  3 , and the connection position of the wire  2 Wa and the n-electrode  23  in the infrared semiconductor laser device  2  are arranged in this order between the first terminal  1 P and the second terminal  2 P in the Y-direction. This prevents the wires  1 Wa,  2 Wa,  3 W from crossing one another. 
     Further, the length of the third terminal  3 P is shorter than the length of each of the first terminal  1 P and second terminal  2 P. The red semiconductor laser device  1 , the infrared semiconductor laser device  2 , and the blue-violet semiconductor laser device  3  are arranged between the first terminal  1 P and the second terminal  2 P in the Y-direction. Also, the length of the third terminal  3 P is set such that it does not overlap in the X-direction with the facet opposite to the facet on the laser beam emitting side of each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3 . This allows the n-electrode  35  in the blue-violet semiconductor laser device  3  and the third terminal  3 P to be connected simply and easily through the wire  3 W. 
     It is preferred that the first terminal  1 P, second terminal  2 P, third terminal  3 P, and fourth terminal  4 P are provided substantially concentrically on the stem  501 , as shown in  FIG. 8  ( a ). This prevents each of the wires that connects each semiconductor laser device and each terminal from crossing one another. 
     Note that the positions in which the red semiconductor laser device  1  and infrared semiconductor laser device  2  are arranged may be reversed. 
     Note also that each of the red semiconductor laser device  1  and infrared semiconductor laser device  2  may have a monolithic structure. 
     In the foregoing fourth embodiment, the wire  1 Wa corresponds to a first wire, the wire  2 Wa corresponds to a second wire, the wire  3 W corresponds to a third wire, and the wire  1 Wb corresponds to a fourth wire. 
     Moreover, in the foregoing fourth embodiment, the Y-direction corresponds to a first direction, the Z-direction corresponds to a second direction, and the X-direction corresponds to a third direction. The stem  501  corresponds to a package, the red semiconductor laser device  1  corresponds to a first semiconductor laser device, the infrared semiconductor laser device  2  corresponds to a second semiconductor laser device, and the blue-violet semiconductor laser device  3  corresponds to a third semiconductor laser device. 
     In addition, in the foregoing fourth embodiment, the n-electrode  13  corresponds to one electrode of the first semiconductor laser device, the n-electrode  23  corresponds to one electrode of the second semiconductor laser device, and the n-electrode  35  corresponds to one electrode of the third semiconductor laser device. The p-electrode  12  corresponds to another electrode of the first semiconductor laser device, the p-electrode  22  corresponds to another electrode of the second semiconductor laser device, and the p-electrode  32  corresponds to another electrode of the third semiconductor laser device. 
     Fifth Embodiment 
       FIG. 9  is a schematic cross-section showing a semiconductor laser apparatus according to a fifth embodiment when assembled on a mount. 
     The semiconductor laser apparatus  550  of the present embodiment differs from the semiconductor laser apparatus  100  of the first embodiment as follows. 
     As shown in  FIG. 9 , the blue-violet semiconductor laser device  3  has a stripe-like ridge portion on a lower surface side. An insulating film  4  is formed on both sides of the ridge portion Ri. A p-electrode  32  is formed to cover a lower surface of the ridge portion Ri, and an n-electrode  35  is formed on an upper surface of the blue-violet semiconductor laser device  3 . In the blue-violet semiconductor laser device  3 , a p-n junction surface  30  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     The red semiconductor laser device  1  has an n-electrode  13  formed on a lower surface and a p-electrode  12  formed on an upper surface. In the red semiconductor laser device  1 , a p-n junction surface  10  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     The infrared semiconductor laser device  2  has an n-electrode  23  formed on a lower surface and a p-electrode  22  formed on an upper surface. In the infrared semiconductor laser device  2 , a p-n junction surface  20  is formed where a p-type semiconductor and an n-type semiconductor are joined together. 
     The red semiconductor laser device  1  and the infrared semiconductor laser device  2 , respectively, are formed on the n-electrode  35  with solder films H therebetween. 
     In this manner, in the semiconductor laser apparatus  550  of the present embodiment, the n-electrode  13  in the red semiconductor laser device  1 , then-electrode  23  in the infrared semiconductor laser device  2 , and the n-electrode  35  in the blue-violet semiconductor laser device  3  are electrically connected. 
     An optical pick-up fabricated by assembling the semiconductor laser apparatus  550  of the embodiment on the mount  500  differs as follows from the optical pick-up fabricated by assembling the semiconductor laser apparatus  100  of the first embodiment on the mount  500 . 
     An insulative submount  60  is provided between the p-electrode  32  in the blue-violet semiconductor laser device  3  and the mount  500 . Thus, the p-electrode  32  and the mount  500  are isolated by the insulative submount  60 . 
     Also, the p-electrode  12  in the red semiconductor laser device  1  and the first terminal  1 P are connected through the wire  1 Wa, the p-electrode  22  in the infrared semiconductor laser device  2  and the second terminal  2 P are connected through the wire  2 Wa, and the p-electrode  32  in the blue-violet semiconductor laser device  3  and the third terminal  3 P are connected through the wire  3 W. 
     In addition, the n-electrode  35  in the blue-violet semiconductor laser device  3  and the mount  500  are connected through the wire  1 Wb. The wire  1 Wb corresponds to a wire on the mount side. 
     With the above-described structure, when the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3  are viewed in the Z direction, the wires  1 Wa,  2 Wa,  3 W,  1 Wb are not crossing one another. 
     In the present embodiment as described above, application of voltage between the mount  500  and the wire  3 W enables driving the blue-violet semiconductor laser device  3 . Similarly, application of voltage between the mount  500  and the wire  1 Wa enables driving the red semiconductor laser device  1 , and the application of voltage between the mount  500  and the wire  2 Wa enables driving the infrared semiconductor laser device  2 . 
     In this manner, each of the blue-violet semiconductor laser device  3 , red semiconductor laser device  1 , and infrared semiconductor laser device  2  can be driven independently. 
     In addition, the blue-violet-beam-emission point  31  in the blue-violet semiconductor laser device  3  that emits a laser beam with a wavelength shorter than the wavelengths of the laser beams from the red semiconductor laser device  1  and the infrared semiconductor laser device  2  is located in the Y-direction between the red-beam-emission point  11  in the red semiconductor laser device  1  and the infrared-beam-emission point  21  in the infrared semiconductor laser device  2 . This allows the blue-violet semiconductor laser device  3  to be easily positioned on a lens when the semiconductor laser apparatus  550  is used in an optical device such as an optical pick-up. 
     As a result, the effect of aberration around the periphery of the lens can be decreased, while the light utilization efficiency can be improved in the blue-violet semiconductor laser device  3 . 
     It is also preferred that the connection position of the wire  1 Wa and the p-electrode  12  in the red semiconductor laser device  1 , the connection position of the wire  3 W and the p-electrode  32  in the blue-violet semiconductor laser device  3 , and the connection position of the wire  2 Wa and the p-electrode  22  in the infrared semiconductor laser device  2  are arranged in this order between the first terminal  12  and the second terminal  2 P in the Y-direction. This prevents the wires  1 Wa,  2 Wa,  3 W from crossing one another. 
     Further, the length of the third terminal  3 P is shorter than the length of each of the first terminal  12  and second terminal  2 P. The red semiconductor laser device  1 , the infrared semiconductor laser device  2 , and the blue-violet semiconductor laser device  3  are arranged between the first terminal  12  and the second terminal  2 P in the Y-direction. Also, the length of the third terminal  3 P is located such that it does not overlap in the X-direction with the facet opposite to the facet on the laser beam emitting side of each of the red semiconductor laser device  1 , infrared semiconductor laser device  2 , and blue-violet semiconductor laser device  3 . This allows the p-electrode  32  in the blue-violet semiconductor laser device  3  and the third terminal  3 P to be connected simply and easily through the wire  3 W. 
     As shown in  FIG. 9 , it is preferred that the first terminal  1 P, second terminal  2 P, third terminal  3 P and fourth terminal  4 P are provided substantially concentrically on the stem  501 . This prevents each of the wires that connects each semiconductor laser device and each terminal from crossing one another. 
     Note that the positions in which the red semiconductor laser device  1  and infrared semiconductor laser device  2  are arranged may be reversed. 
     The red semiconductor laser device  1  and infrared semiconductor laser device  2  may each have a monolithic structure. 
     In the foregoing fifth embodiment, the wire  1 Wa corresponds to a first wire, the wire  2 Wa corresponds to a second wire, the wire  3 W corresponds to a third wire, and the wire  1 Wb corresponds to a fourth wire. 
     Moreover, in the foregoing fifth embodiment, the Y-direction corresponds to a first direction, the Z-direction corresponds to a second direction, and the X-direction corresponds to a third direction. The stem  501  corresponds to a package, the red semiconductor laser device  1  corresponds to a first semiconductor laser device, the infrared semiconductor laser device  2  corresponds to a second semiconductor laser device, and the blue-violet semiconductor laser device  3  corresponds to a third semiconductor laser device. 
     In addition, in the foregoing fifth embodiment, the p-electrode  12  corresponds to one electrode of the first semiconductor laser device, the p-electrode  22  corresponds to one electrode of the second semiconductor laser device, and the p-electrode  32  corresponds to one electrode of the third semiconductor laser device. The n-electrode  13  corresponds to another electrode of the first semiconductor laser device, the n-electrode  23  corresponds to another electrode of the second semiconductor laser device, and the n-electrode  35  corresponds to another electrode of the third semiconductor laser device. 
     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.