JP2001223442A - Light source unit and light pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of a light source unit and light pickup device which emits laser light of different wavelengths by which power can be easily supplied to laser diode chips even if they are laminated, an adjustment of an optical axis can be made easily, and the heat radiation property can be improved. SOLUTION: In the light source unit 10, the laser diode chips 11, 12 are laminated with a conductive heat radiation board 7 made from a metal plate put inbetween. The heat radiation board 7 overhangs the laser diode chips 11, 12 on both sides. One of the overhanging parts 70 is used as a power supplying section 30 which is to be wire-bonded 31. The heat radiation board 7 is so disposed that an end face 77 located on the side of light emission end faces 110, 120 of the laser diode chips 11, 12 recedes in the optical axis direction from the light emission end faces 110, 120.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a light source unit for emitting laser beams having different wavelengths, and an optical pickup device using the light source unit. More specifically, the present invention relates to a technique for arranging laser diode chips used in a light source unit.

[0002]

2. Description of the Related Art Conventionally, as an optical recording disk (optical recording medium), a CD (compact disk) having a thickness of 1.2 mm has been mainly used, but with the practical use of a red laser diode having a short wavelength. Thus, a DVD (digital versatile disk) having a thickness of 0.6 mm, which is about the same size as a CD and has a large capacity, is being commercialized. That is, since the size of the light spot formed on the disk surface of the optical recording medium is proportional to the square of the wavelength, a CD using a 780 nm infrared infrared AlGaAs laser diode is used.
Than 635/650 nm band red light AlG
A DVD using an aInP-based laser diode can realize high-density recording because the wavelength is shorter.

[0003] However, from the viewpoint of utilizing existing data, it is important that a DVD drive device can reproduce data from a CD optical recording disk (hereinafter, referred to as a CD disk). Here, the wavelength is 635
According to the / 650 nm red laser beam, by operating the aperture of the objective lens with respect to the optical recording disk to change the depth of focus, it is basically possible to record and play back DVD-based discs and play back CD-based discs. It is. However, 6
The 35/650 nm red laser beam corresponds to the absorption band of the organic dye used for CD-R (write-once-read-only CD) among CD-based discs, and thus has a wavelength of 635/650 nm.
Recording / reproducing of CD-R is impossible with the 650 nm band red laser light.

Therefore, one optical pickup device has a first laser diode for emitting a first laser beam having a wavelength of 635/650 nm and a second laser diode for emitting a second laser beam having a wavelength of 780 nm. Equipped with
In addition, a laser light emitted from these laser diodes is guided on a common optical path using various optical elements.

For example, Japanese Patent Application Laid-Open No. 10-326428 discloses a first laser diode 1 as shown in FIG.
The first laser beam L1 having a wavelength of 635/650 nm emitted from 1X and the second laser beam L2 having a wavelength of 780 nm emitted from the second laser diode 12X are shared by the prism 31 using a common optical path L0. An optical pickup device configured to be directed above is disclosed.

Japanese Unexamined Patent Application Publication No. 10-289468 discloses a first laser diode 11X as shown in FIG.
A first laser beam L1 having a wavelength of 635/650 nm and a second laser beam L2 having a wavelength of 780 nm emitted from the second laser diode 12X are shared by a common optical path L0 using a diffraction grating 32. An optical pickup device configured to be directed above is disclosed.

According to the optical pickup device having such a configuration, it is possible to reproduce a signal from a DVD using the first laser beam L1 having a short wavelength and to use the second laser beam L2 having a long wavelength. Signal reproduction from a CD-based disc. Further, the first laser light L
Since the first and second laser beams L2 are guided on the common optical path L0, the objective lens and the photodetector can be shared.
Therefore, in such an optical pickup device, the optical system can be simplified.

[0008]

However, like a conventional optical pickup device using two-wavelength laser light,
In the configuration in which the two laser diodes 11X and 12X are arranged at positions separated from each other and oriented in a predetermined direction, when assembling the optical pickup device, it takes time to adjust the optical axes of both, so that the productivity is low. There is a problem.

A light source which can simplify the adjustment of the optical axis of the two laser diode chips when assembling the optical pickup device by housing the hybrid mounting of the two laser diode chips in a single package. The unit is being considered.

As a light source unit having such a configuration, for example, as shown in FIG. 8, a unit in which two laser diode chips 11 and 12 are stacked in two stages is considered.

However, when the two laser diode chips 11 and 12 are stacked, the heat dissipation of both the laser diode chips 11 and 12 is significantly reduced, so that there is a problem that the light emission characteristics and reliability are reduced.

In the configuration shown in FIG. 8, when two laser diode chips 11 and 12 having the same size are used, each electrode 11 formed on the upper and lower surfaces is used.
Even when power is supplied to two electrodes 112, 121 overlapping one another among the electrodes 1, 112, 121, 122, these electrodes 112, 121 have no space for wire bonding. Therefore, an area 125 for applying the wire bonding 31 to the lower laser diode chip 11 is secured.
Since it is necessary to supply power to the electrodes 112 and 121 of 1 and 12, there is a problem that the size of the lower laser diode chip 11 becomes considerably large.

Further, in the light source unit 10 shown in FIG. 8, the two laser diode chips 11 and 12 are joined using a joining material such as an adhesive or a fusing agent so that the light emitting end faces 110 and 120 face in the same direction. At this time, as shown in FIG.
It goes around to the light emitting end faces 110 and 120 of 1 and 12,
The laser diode chips 11 and 12 may malfunction. Such a problem occurs even when the light emitting end face 120 is positioned forward of the light emitting end face 110 by shifting the laser diode chips 11 and 12 back and forth as shown in FIG.
It is impossible to completely prevent the joining material 40 from wrapping around 10.

In view of these problems, an object of the present invention is to provide a light source unit and an optical pickup device that emit laser beams having different wavelengths, even if laser diode chips are stacked, on these laser diodes easily. An object of the present invention is to propose a configuration capable of supplying power, simplifying the adjustment work of the optical axis, and improving heat dissipation.

Another object of the present invention is to propose a configuration in this kind of light source unit and optical pickup device that can prevent a bonding material from wrapping around a light emitting end face of a laser diode chip.

[0016]

According to the present invention, there is provided at least a first laser diode chip for emitting a first laser beam, and a first laser diode chip having a wavelength different from that of the first laser diode chip. In a light source unit including a second laser diode chip that emits a second laser beam, the first laser diode chip and the second laser diode chip are stacked with a conductive heat sink interposed therebetween. It is characterized by the following.

In the light source unit to which the present invention is applied, the first
Since the laser diode chip and the second laser diode chip are mounted with the heat sink interposed therebetween, the relative positions of the first laser diode chip and the second laser diode chip are fixed. For this reason, the optical axis can be easily adjusted between the first laser diode chip and the second laser diode chip. Therefore, in the manufacturing process of the light source unit and the manufacturing process of the optical pickup device, the operation of adjusting the optical axis can be simplified. Further, since the first laser diode chip and the second laser diode chip are stacked with a heat radiating plate interposed therebetween, heat radiation from these laser diode chips is high.

Since the heat radiating plate is conductive, the first laser diode chip is connected to the heat radiating plate through the heat radiating plate by wiring connection such as wire bonding. Power can be supplied to the electrodes that are connected and the electrodes that are joined to the heat sink in the second laser diode chip.

In the present invention, the radiator plate is provided with the first heat sink.
It is preferable to protrude from between the laser diode chip and the second laser diode chip. With this configuration, the protruding portion of the heat sink can be used as a space for wiring connection such as wire bonding. Further, since the heat dissipation area increases, the heat dissipation of the heat dissipation plate can be improved.

Since power can be supplied from the heat radiating plate to each electrode of the laser diode chip bonded to the heat radiating plate, it is not necessary to increase the size of one laser diode chip. Therefore, in the present invention, the first laser diode chip and the second laser diode chip having substantially the same area can be used.

In the present invention, the first laser diode chip and the second laser diode chip are stacked so that the light emitting end faces face in the same direction, and the heat sink has an end on the light emitting end face side. The first laser diode chip and the second laser diode chip are arranged so as to be located behind the light emitting end face of the first laser diode chip and the light emitting end face of the second laser diode chip in the optical axis direction. It is preferable to be bonded to the laser diode chip by a bonding material. With such a configuration, even if the bonding material reaches the end on the light emitting end face side of the heat sink, the end of the heat sink is connected to the light emitting end face of the first laser diode chip and the second laser diode chip. Since it is located at the position retracted from the light emitting end face, the bonding material does not wrap around to the light emitting end face of the laser diode chip. Therefore, it is possible to avoid a problem that the laser diode chip malfunctions due to the wraparound of the bonding material.

Such a light source unit includes, for example, an objective lens for converging laser light emitted from a laser light source on an optical recording medium, and a photodetector for receiving return light reflected on the optical recording medium. In an optical pickup device having the same, it is preferable to use it as the laser light source.

For such an optical pickup device,
When the light source unit according to the present invention is used, the wavelength of the first laser light is 635 nm or 650 nm,
If the wavelength of the second laser beam is 780 nm, a single optical pickup device can suitably reproduce signals from both DVD and CD discs.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

[Configuration Example of Optical Pickup Device] Before describing a light source unit to which the present invention is applied, an example of an optical pickup device using this light source unit will be described with reference to FIG.

FIG. 1 is a schematic diagram showing an example of an optical pickup device on which a light source unit to which the present invention is applied is mounted.

In FIG. 1, the optical pickup device 1 according to the present embodiment has 635 nm (or 650 nm) and 780 nm.
Signals can be reproduced from both DVD and CD discs using a laser beam of nm.

More specifically, the optical pickup device 1 of this embodiment has a wavelength of 635 nm (or 650 nm).
m), a light source unit 10 for emitting the first laser light L1 and the second laser light L2 having a wavelength of 780 nm. The first laser light L1 and the second laser light L2 emitted from the light source unit 10 are transmitted through a common optical system to the DVD as the optical recording disk 2 (optical recording medium).
Alternatively, it is led to a CD-based disc. The return light from the optical recording disk 2 is also guided to a common photodetector 115 (photodiode or phototransistor) via a common optical system. The common optical system includes a diffraction grating 103 that generates three beams from the first laser light L1 and the second laser light L2, a half mirror 104 that partially reflects light that has passed through the diffraction grating 103, and a half mirror 1
A collimating lens 105 for converting the light reflected from the light source 04 into a parallel light beam, and a total reflection mirror 1 for bending the traveling direction of the light emitted from the collimating lens 105 at a right angle.
06, and an objective lens 107 for converging the light reflected from the total reflection mirror 106 on the disk surface of the optical recording disk 2. Also in the example shown here, the diffraction grating 103 is used, but this diffraction grating 103 generates only three beams, and the first laser light L1
Is not combined with the optical axis of the second laser beam L2.

The common optical system includes an optical recording disk 2
A sensor lens 109 that converges the return light reflected from the object by being guided by the objective lens 107, the total reflection mirror 106, the collimating lens 105, and the half mirror 104, and astigmatism is given by the sensor lens 109. Photodetector 1 for detecting return light
15 is also included.

In the above example, in the light source unit 10, the optical axis of the first laser light L1 and the second laser light L
The optical system for guiding the first laser light L1 and the second laser light L2 to the common optical system is not provided, assuming that the separation distance from the second optical axis is substantially negligible. If the distance between the optical axis of the laser light L1 and the optical axis of the second laser light L2 cannot be neglected, the first laser light L1 and the second laser light L2 are overlapped on the optical axis and shared. An optical system for guiding the system may be provided.

The optical pickup device 1 configured as described above
In reproducing the signal from the DVD as the optical recording disk 2, the light source unit 10 outputs
A first laser beam L1 of 5 nm (or 650 nm) is emitted. The first laser light L1 emitted from the light source unit 10 has its traveling direction bent by 90 degrees by the half mirror 104 and enters the collimator lens 105. The first laser light L1 incident on the collimator lens 105 is converted by the collimator lens 105 into a substantially parallel light beam. The first laser light L1 converted into a parallel light flux is converged as a light spot on the DVD disk surface by the total reflection mirror 106 and the objective lens 107.

The return light of the first laser light L1 reflected by the DVD disk surface passes through the common optical system again and is guided to the photodetector 115. That is, the return light from the DVD 2 is focused on the photodetector 115 via the objective lens 107, the total reflection mirror 106, the collimator lens 105, the half mirror 104, and the sensor lens 109. The photodetector 115 has, for example, a four-divided light-receiving surface, and a light-receiving signal detected on this light-receiving surface is subjected to signal reproduction processing by a control device (not shown).

On the other hand, as the optical recording disk 2, C
When reproducing a signal from a D-system disc, the light source unit 10 outputs a second laser beam L2 having a wavelength of 780 nm.
Is emitted. The second laser light L2 emitted from the light source unit 10 is also a half laser light similarly to the first laser light L1.
The light is converged as a light spot on the disc surface of the CD disc by the mirror 104, the collimating lens 105, the total reflection mirror 106, and the objective lens 107.

The return light of the second laser beam L2 reflected on the disk surface of the CD disk also passes through the common optical system again, is guided to the photodetector 115, and is detected on the light receiving surface of the photodetector 115. The received light signal is subjected to signal reproduction processing by a control device (not shown).

[Embodiment 1] FIGS. 2 and 3 show
FIG. 2 is a perspective view and a side view showing a schematic configuration of a main part of a light source unit used in the optical pickup device shown in FIG. 1 and the like. In FIG. 3, the wire bonding is omitted. In the following description, portions common to the conventional configuration will be denoted by the same reference numerals.

As shown in FIGS. 2 and 3, in the light source unit 10 used as a laser light source in the optical pickup device, AlGaIn which emits a first laser light L1 (red light) having a wavelength of 635 nm (or 650 nm) is used.
P-type first laser diode chip 11 and wavelength 7
A that emits the second laser light L2 (infrared light) of 80 nm
The lGaAs-based second laser diode chip 12 is mounted on a common heat sink 8 (submount) made of a metal plate or the like, and is housed in a common package (not shown) in this state to be hybridized. ing.

In the present embodiment, the first laser diode chip 11 and the second laser diode chip 12 are stacked with a predetermined thickness of the heat radiating plate 7 made of a metal plate interposed therebetween. Chip 1
1, heat sink 7, and second laser diode chip 1
2 are stacked in this order from bottom to top. Therefore, the first
Of the electrodes 111 and 112 formed on both surfaces of the laser diode chip 11, the electrode 111 is bonded to the upper surface 81 of the heat sink 8, and the electrode 112 is electrically conductive to the lower surface 71 of the heat sink 7. It is joined by a joining material. Also, the second laser diode chip 12
Of the electrodes 121 and 122 formed on both surfaces thereof, the electrode 121 is bonded to the upper surface 72 of the heat sink 7 by a conductive bonding material, and the electrode 122 is open upward. For this reason, if the wire bonding 33 is performed on the upper surface 81 of the heat sink 8, the electrode 111 of the first laser diode chip 11 is
Can be powered. Further, the wire bonding 32 can be directly performed on the electrode 122 of the second laser diode chip 12.

The bonding material used here is a conductive adhesive or a conductive fusing agent.

Further, the heat radiating plate 7 protrudes from both sides between the first laser diode chip 11 and the second laser diode chip 12, and these protruding portions 7 are formed.
One of the 0s is used as the power supply unit 30 to which the wire bonding 31 has been applied. Therefore, power can be supplied to the electrodes 112 and 121 of the first laser diode chip 11 and the second laser diode chip 12 via the heat sink 7. Therefore, in the present embodiment, unlike the one described with reference to FIG. 8, the first laser diode chip 11 and the second laser diode chip 12 have the same size, such as the same area. ing.

In the present embodiment, the first laser diode chip 11 and the second laser diode chip 12 have their light emitting end faces 110 and 1 so that their optical axes are parallel to each other.
20 are stacked in the same direction, and the light emitting end faces 110 and 120 are on the same plane.

On the other hand, the heat radiating plate 7 is
The end faces 77 located on the 0 and 120 sides are arranged behind the light emitting end face 110 of the first laser diode chip 11 and the light emitting end face 120 of the second laser diode chip 12 in the optical axis direction. For this reason, even if the bonding material 40 goes around to the end face 77 of the heat sink 7 between the first laser diode chip 11 and the heat sink 7, the bonding material 40 is connected to the end face 77 and the first laser diode chip. It stops at the corner formed by the eleventh electrode 112 and does not reach the light emitting end face 110 of the first laser diode chip 11. In addition, the bonding material 40 is provided between the second laser diode chip 12 and the heat sink 7 so that the end face 7 of the heat sink 7 is closed.
7, the bonding material 40 stops at the corner formed by the end face 77 and the electrode 121 of the second laser diode chip 12, and goes to the light emitting end face 120 of the second laser diode chip 12. There is no.

As described above, in the light source unit 10 of the present embodiment, the first laser diode chip 11 and the second laser diode chip 12 are integrally mounted on the heat sink 8, so that when the optical pickup device is assembled, The adjustment of the optical axis between the first laser diode chip 11 and the second laser diode chip can be simplified. Further, the distance between the first laser diode chip 11 and the second laser diode chip 12 can be controlled with high accuracy by the thickness of the heat sink 7.
Therefore, the operation of adjusting the optical axis when manufacturing the light source unit 10 and the optical pickup device can be simplified.

Also, the first laser diode chip 11
And the second laser diode chip 12 are stacked with the heat radiating plate 7 interposed therebetween, so that the heat generated by the first laser diode chip 11 and the second laser diode chip 12 is efficiently transmitted through the heat radiating plate 7. Dissipates heat well. Moreover, since the heat radiation plate 7 protrudes from between the first laser diode chip 11 and the second laser diode chip 12, the heat radiation of the heat radiation plate 7 is in a considerably high state. Therefore, the temperature rise of the first laser diode chip 11 and the second laser diode chip 12 can be suppressed, so that the first laser diode chip 11
In addition, it is possible to prevent a malfunction and a decrease in reliability of the second laser diode chip 12.

Further, the heat sink 7 has a first laser diode chip 11 and a second laser diode chip 12.
The wire bonding 31 is performed here by using the protruding portion 70 extending from the space between them as the power supply portion 30. Therefore,
The electrode 11 joined to the heat sink 7 in the first laser diode chip 12 using the heat sink 7 as a common electrode
In the second and second laser diode chips 12, power can be supplied to the electrode 121 bonded to the heat sink 7. Therefore, the first laser diode chip 11 disposed on the lower side does not need to be formed into a large size to secure an area for performing the wire bonding 31, so that the second laser diode chip 12 Small ones of the same size can be used.

Further, since the heat radiating plate 7 is disposed at a position retracted from the first laser diode chip 11 and the second laser diode chip 12, the first
The bonding material 40 does not reach the light emitting end faces 110 and 120 of the laser diode chip 11 and the second laser diode chip 12. Therefore, the first laser diode chip 11 and the second laser diode chip 12 do not malfunction due to the wraparound of the bonding material 40.

In the light source unit 10 of this embodiment, as shown in FIG. 3, the light emitting end face 110 of the first laser diode chip 11 and the end face 80 of the heat sink 8 are on the same plane. When a conductive bonding material is also used to bond the chip 11 and the heat sink 8, the heat sink 8 may be connected to the first laser diode chip 11 in order to prevent the bonding material from reaching the light emitting end face 110. The end face 80 on the light emitting end face 110 side may be retracted to the position shown by the dashed line L1 in FIG.

[Embodiment 2] FIGS. 4 and 5 show
It is the perspective view and the top view which show schematic structure of the principal part of the light source unit used for the optical pick-up apparatus. In FIG. 5, the wire bonding is omitted.

As shown in FIGS. 4 and 5, in the light source unit 10 of this embodiment, the wavelength is 635 nm (or 65 nm).
0 nm) and a first laser diode chip 11 for emitting a first laser beam L1 (red light) having a wavelength of 780 nm.
The second laser diode chip 12 for emitting the second laser light L2 (infrared light) is mounted on a common insulating submount 8 ', and in this state, a common package (not shown) is used. It is housed in a hybrid.

Also in this embodiment, the first laser diode chip 11 and the second laser diode chip 12 are stacked with the conductive heat radiating plate 7 made of a metal plate interposed therebetween. Laser diode chip 1
1, heat sink 7, and second laser diode chip 1
2 are stacked in this order in the horizontal direction. Therefore, the electrode 112 of the first laser diode chip 11 is
Is bonded to the other surface 71 'by a conductive bonding material, and the electrode 111 is open laterally. Also, the second
The electrode 121 of the laser diode chip 12 is bonded to the other surface 72 ′ of the heat sink 7 by a conductive bonding material, and the electrode 122 is open laterally. For this reason, the electrode 111 of the first laser diode chip 11,
And the electrode 122 of the second laser diode chip 12
In this case, wiring connection can be made directly by wire bonding 36, 37 or the like.

The heat radiating plate 7 protrudes upward and backward from between the first laser diode chip 11 and the second laser diode chip 12, and the protruding portions 78 are subjected to wire bonding 31. Used as the power supply unit 30. Therefore, power can be supplied to the electrodes 112 and 121 of the first laser diode chip 11 and the second laser diode chip 12 via the heat sink 7. For this reason, in this embodiment,
Unlike the one described with reference to FIG. 8, the first laser diode chip 11 and the second laser diode chip 12 have the same size, such as equal areas.

Also in this embodiment, the first laser diode chip 11 and the second laser diode chip 12
The light emitting end faces 110 of each other so that their optical axes are parallel,
120 are stacked in the same direction, and the light emitting end faces 110 and 120 are on the same plane.

On the other hand, the heat radiating plate 7 is
The end faces 77 located on the 0 and 120 sides are arranged behind the light emitting end face 110 of the first laser diode chip 11 and the light emitting end face 120 of the second laser diode chip 12 in the optical axis direction. For this reason, even if the bonding material 40 goes around to the end face 77 of the heat sink 7 between the first laser diode chip 11 and the heat sink 7, the bonding material 40 is connected to the end face 77 and the first laser diode chip. It stops at the corner formed by the eleventh electrode 112 and does not reach the light emitting end face 110 of the first laser diode chip 11. In addition, the bonding material 40 is provided between the second laser diode chip 12 and the heat sink 7 so that the end face 7 of the heat sink 7 is closed.
7, the bonding material 40 stops at the corner formed by the end face 77 and the electrode 121 of the second laser diode chip 12, and goes to the light emitting end face 120 of the second laser diode chip 12. There is no.

As described above, also in the light source unit 10 of the present embodiment, the distance between the first laser diode chip 11 and the second
Can be controlled with high precision by the thickness of the light source unit 10 and the optical pickup device can be simplified in adjusting the optical axis when the light source unit 10 and the optical pickup device are manufactured. It has the same effect as.

[0054]

As described above, in the light source unit according to the present invention, the first laser diode chip and the second laser diode chip are mounted with the heat radiating plate interposed therebetween. And the second laser diode chip has a fixed relative position. Therefore, the optical axis can be easily adjusted between the first laser diode chip and the second laser diode chip, so that the optical axis adjustment work is performed in the light source unit manufacturing process and the optical pickup manufacturing process. Can be simplified. Further, since the first laser diode chip and the second laser diode chip are stacked with a heat radiating plate interposed therebetween, heat radiation from these laser diode chips is high.

If the heat radiating plate protrudes from between the first laser diode chip and the second laser diode chip, this protruding portion is supplied to the first laser diode chip and the second laser diode chip. Since wire bonding or the like can be performed as a part, it is not necessary to increase the size of one laser diode chip in order to secure a place for wire bonding. Therefore, the first laser diode chip and the second
The laser diode chips having the same area can be used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an optical pickup device on which a light source unit to which the present invention is applied is mounted.

FIG. 2 is a perspective view showing a schematic configuration of a main part of a light source unit used in the optical pickup device according to Embodiment 1 of the present invention.

FIG. 3 is a side view showing a schematic configuration of a main part of the light source unit shown in FIG. 2;

FIG. 4 is a perspective view illustrating a schematic configuration of a main part of a light source unit used in an optical pickup device according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a schematic configuration of a main part of the light source unit shown in FIG.

FIG. 6 is an explanatory view showing an arrangement of a laser light source and a prism used in a conventional optical pickup device.

FIG. 7 is an explanatory diagram showing an arrangement of a laser light source and a diffraction grating used in another conventional optical pickup device.

FIG. 8 is a perspective view illustrating a schematic configuration of a light source unit used in an optical pickup device according to a reference example.

FIG. 9 is a side view showing a schematic configuration of the light source unit shown in FIG.

FIG. 10 is a side view showing a schematic configuration of a light source unit used in an optical pickup device according to another reference example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 optical pickup device 2 optical recording disk (optical recording medium) 8 heat sink 8 ′ submount 10 light source unit 11 first laser diode chip 12 second laser diode chip 30 power supply unit 40 bonding material 70, 78 protruding portion of heat sink 103 Diffraction grating 104 Half mirror 105 Collimating lens 106 Total reflection mirror 107 Objective lens 109 Sensor lens 110, 120 Light emitting end face 111, 112, 121, 122 Electrode 31, 32, 33, 36, 37 Wire bonding 115 Photodetector L1 First 1st laser beam L2 2nd laser beam

Claims (6)

[Claims] At least a first laser diode chip that emits a first laser light and a second laser diode chip that emits a second laser light having a wavelength different from that of the first laser diode chip are provided. In the light source unit provided, the first laser diode chip and the second laser diode chip are stacked with a conductive heat radiating plate interposed therebetween. 2. The light source unit according to claim 1, wherein the heat radiating plate protrudes from between the first laser diode chip and the second laser diode chip. 3. The light source unit according to claim 1, wherein the first laser diode chip and the second laser diode chip have substantially the same area. 4. The method according to claim 1, wherein
The first laser diode chip and the second laser diode chip are stacked so that the light emitting end faces thereof face in the same direction, and the heat sink has an end on the light emitting end face side of the first laser diode chip. The first laser diode chip, the second laser diode chip, and the bonding material in a state where the first laser diode chip and the second laser diode chip are disposed so as to be located behind the light emitting end face of the second laser diode chip and the light emitting end face of the second laser diode chip. A light source unit characterized by being joined by. 5. An optical pickup device using the light source unit defined in any one of claims 1 to 4, wherein the light source unit, the first laser beam emitted from the light source unit, and the second An optical pickup device comprising: an objective lens for converging the laser light on an optical recording medium; and a photodetector for receiving return light reflected on the optical recording medium. 6. The optical pickup device according to claim 5, wherein the wavelength of the first laser light is 635 nm or 650 nm, and the wavelength of the second laser light is 780 nm.