JP2008187082A - Laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser device efficiently radiating heat generated by a laser element to a base when the element is driven. <P>SOLUTION: The laser device 30 comprises the base 1, two semiconductor laser elements 10 and 20 fixed onto the base while having a predetermined gap D1, and a heat conduction portion 2 which is made of an insulating material having larger heat conductivity than air and connects the two semiconductor laser elements to each other. Insulating layers 60 and 80 are provided on a predetermined gap side of the two semiconductor laser elements which are connected by the heat conduction portion 2 through the insulating layers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laser device, and more particularly, to a laser device including a plurality of semiconductor laser elements.

There is an optical pickup as one form of a laser device for recording and reproducing information on an optical disc such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and a next-generation optical disc (for example, Blu-ray Disc).
A semiconductor laser element is generally used as the light source of the optical pickup.
Since the oscillation wavelength of a semiconductor laser element varies depending on the type of optical disk, for example, a semiconductor laser element having a near-infrared oscillation wavelength of 780 nm band is used for CD, and a red oscillation of 635 nm band or 650 nm band is used for DVD. A semiconductor laser element having a blue wavelength in the 405 nm band is used for a Blu-ray Disc.
In view of this, a laser apparatus is generally provided with a plurality of semiconductor laser elements having different oscillation wavelengths so as to correspond to these optical discs.

An example of a laser apparatus including a plurality of semiconductor laser elements having different oscillation wavelengths is disclosed in Patent Document 1.
Japanese Patent Laid-Open No. 11-112089

However, when the semiconductor laser element used in the laser apparatus is downsized in accordance with the recent miniaturization of the laser apparatus, the contact between the semiconductor laser element and a base such as a submount on which the semiconductor laser element is mounted is fixed. Since the area becomes small, it becomes difficult to efficiently dissipate heat generated from this element to the base when the semiconductor laser element is driven.
In particular, in the case of a semiconductor laser device in which the light emitting points described in Patent Document 1 are arranged so as to be offset toward one surface, the heat conductivity of air in contact with this one surface is poor, and therefore the heat dissipation efficiency is further deteriorated. Improvement is desired.
If the heat dissipation efficiency when the semiconductor laser element is driven is poor, the temperature characteristics of the semiconductor laser element are deteriorated and the aging life is shortened.

  Therefore, the problem to be solved by the present invention is to provide a laser device capable of efficiently dissipating heat based on the heat generated from the element when the semiconductor laser element is driven.

In order to solve the above problems, each invention of the present application has the following means.
1) a base (1), two semiconductor laser elements (10, 20) fixed on the base with a predetermined gap (D1), and an insulating material having a higher thermal conductivity than air And a heat conducting part (2) for connecting the two semiconductor laser elements to each other.
2) A base (41), two semiconductor laser elements (50, 70) fixed on the base with a predetermined gap (D2), and a material having a higher thermal conductivity than air. A heat conducting portion (42) for connecting the two semiconductor laser elements, and the two semiconductor laser elements each have an insulating layer (60, 80) on the predetermined gap side, A heat conduction part is a laser apparatus (90) characterized by connecting said two semiconductor laser elements through each said insulating layer.

  According to the present invention, it is possible to efficiently dissipate heat generated from the element when the semiconductor laser element is driven to the base.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to FIGS. 1 and 2 according to a first embodiment and a second embodiment which are preferred embodiments.
1 and 2 are schematic perspective views for explaining a first embodiment and a second embodiment of the laser apparatus of the present invention, respectively.
In the first and second embodiments, an optical pickup will be described as an example of the laser device.

<First embodiment>
As shown in FIG. 1, an optical pickup 30 as a laser device includes a submount 1 as a base, and a first semiconductor laser having a near-infrared emission wavelength of 780 nm band mounted and fixed on the submount 1. An element 10, a second semiconductor laser element 20 having a red emission wavelength of 650 nm band mounted and fixed with a predetermined gap D 1 in the vicinity of the first semiconductor laser element 10 on the submount 1; And a heat radiating material 2 having an insulating property filled in a predetermined gap D1 in contact with each of the first semiconductor laser element 10 and the second semiconductor laser element 20.
The first semiconductor laser element 10 is a light source for recording / reproducing information on a DVD (Digital Versatile Disc), and the second semiconductor laser element 20 is a light source for recording / reproducing information on a CD (Compact Disc). .
In general, a semiconductor laser element used for a DVD has a substantially parallelogram-shaped cross-sectional shape depending on its crystal orientation.
In the first embodiment, the width W1 of the predetermined gap D1 is 30 μm.

In the first semiconductor laser element 10, an n-type cladding layer 12, an active layer 13, and a p-type cladding layer 14 are sequentially stacked on an n-type semiconductor substrate 11 (the downward direction in FIG. 1 is the stacking direction). It has a laminated structure. On the p-type cladding layer 14, a p-type ridge 15 and an n-type current blocking layer 16 formed so as to fill the step between the p-type ridge 15 are formed. A p-type contact layer 17 and a p-side electrode 18 are laminated on 16. An n-side electrode 19 is formed on the surface opposite to the stacking direction of the n-type semiconductor substrate 11.
Then, by flowing a predetermined current from an external power source toward the n-side electrode 19 from the p-side electrode 18, a laser beam having an oscillation wavelength of 650 nm band from the light emitting region corresponding to the p-type ridge 15 in the active layer 13. L10 is emitted.
By the way, the n-type current blocking layer 16 is provided so that a current applied from an external power source flows intensively to the p-type ridge 15 without flowing to the n-type current blocking layer 16.

In the second semiconductor laser element 20, an n-type cladding layer 22, an active layer 23, and a p-type cladding layer 24 are sequentially stacked on an n-type semiconductor substrate 21 (the downward direction in FIG. 1 is the stacking direction). It has a laminated structure. On the p-type cladding layer 24, an n-type current blocking layer 26 is formed so as to fill a step between the p-type ridge 25 and the p-type ridge 25, and on the p-type ridge 25 and the n-type current blocking layer 26. The p-type contact layer 27 and the p-side electrode 28 are stacked. An n-side electrode 29 is formed on the surface opposite to the stacking direction of the n-type semiconductor substrate 21.
Then, by passing a predetermined current from the external power source toward the n-side electrode 29 from the p-side electrode 28, a laser beam having an oscillation wavelength of 780 nm band from the light emitting region corresponding to the p-type ridge 25 in the active layer 23. L20 is emitted.
Similarly, the n-type current blocking layer 26 is provided so that a current applied from an external power supply flows intensively to the p-type ridge 25 without flowing to the n-type current blocking layer 26.

Further, the p-type ridge 15 and the p-type ridge 25 are provided so as to be offset in a direction approaching each other.
By providing the p-type ridge 15 and the p-type ridge 25 so as to be close to each other in the approaching direction, the light emitting region of the first semiconductor laser device 10 and the light emitting region of the second semiconductor laser device 20 are brought close to each other. Therefore, when the optical pickup 30 is used to record and reproduce information on the optical disk, the optical paths of the laser beams of the semiconductor laser elements 10 and 20 irradiated on the optical disk can be made closer to each other. For this reason, since a common optical system can be used, the number of parts can be reduced.
The first semiconductor laser element 10 and the second semiconductor laser element 20 can be manufactured using a known semiconductor process.

The submount 1 has a function of efficiently radiating heat generated from the element driven when the first semiconductor laser element 10 or the second semiconductor laser element 20 is driven. It is preferable to use a large material. Silicon (Si), copper (Cu), aluminum nitride (AlN), or the like can be used as a material having high thermal conductivity.
In the first example, the submount 1 was obtained by cutting a silicon wafer into a predetermined dimension.

Further, by configuring the heat dissipating material 2 with an insulating material having a thermal conductivity higher than that of air, heat generated from the element driven when the first semiconductor laser element 10 or the second semiconductor laser element 20 is driven can be generated. Heat can be efficiently radiated to other elements that are not driven.
In the first embodiment, an insulating material in which silicon powder is contained in a resin is used as the heat dissipating material 2, and the heat dissipating material 2 is filled in a predetermined gap D1 using a dispenser.

  According to the optical pickup 30 described above, when the optical pickup 30 is used to record / reproduce information on, for example, a CD, the first semiconductor laser element 10 is driven, which is generated in the first semiconductor laser element 10. Heat can be directly released to the submount 1, and the heat dissipating material 2 located in the vicinity of the light emitting region and in contact with the first semiconductor laser element 10 and the second semiconductor laser element 20 in contact with the heat dissipating material 2 are used. Thus, the heat can be released to the submount 1 indirectly, so that the heat radiation efficiency can be improved as compared with the conventional case.

  Further, according to the optical pickup 30 described above, when information is recorded on and reproduced from, for example, a DVD using the optical pickup 30, the second semiconductor laser element 20 is driven. The generated heat can be directly released to the submount 1, and the heat dissipating material 2 located in the vicinity of the light emitting region and in contact with the second semiconductor laser element 20, and the first semiconductor laser element 10 in contact with the heat dissipating material 2, Therefore, the heat dissipation efficiency can be improved as compared with the conventional case.

  Therefore, according to the optical pickup described above, since the heat generated from the element when the semiconductor laser element is driven can be radiated more efficiently than the conventional one, the temperature characteristic of the semiconductor laser element is improved. The aging life is improved.

  Further, according to the optical pickup described above, even when the semiconductor laser element is downsized, the heat generated from the element when the semiconductor laser element is driven can be directly radiated to the base, and the heat radiating material and the drive can be driven. Since heat can be radiated to the base indirectly through other semiconductor laser elements that are not present, the efficiency of heat radiation is improved as compared with the prior art, so that the temperature characteristics of the semiconductor laser elements are improved and the aging life is improved. There is an effect.

<Second embodiment>
Next, an optical pickup 90 which is a laser apparatus of the second embodiment will be described with reference to FIG.
As shown in FIG. 2, an optical pickup 90 as a laser device includes a submount 41 as a base, and a third semiconductor laser having a near-infrared emission wavelength of 780 nm band mounted and fixed on the submount 41. An element 50, a fourth semiconductor laser element 70 having a red emission wavelength of 650 nm band mounted and fixed with a predetermined gap D 2 in the vicinity of the third semiconductor laser element 50 on the submount 41; 3 and the fourth semiconductor laser element 70 are in contact with each other, and a heat radiation material 42 filled in a predetermined gap D2 is provided.
The third semiconductor laser element 50 is a light source for recording / reproducing information on a DVD (Digital Versatile Disc), and the fourth semiconductor laser element 70 is a light source for recording / reproducing information on a CD (Compact Disc). .
In general, a semiconductor laser element used for a DVD has a substantially parallelogram-shaped cross-sectional shape depending on its crystal orientation.
In the second embodiment, the width W2 of the predetermined gap D2 is 30 μm.

In the third semiconductor laser element 50, an n-type cladding layer 52, an active layer 53, and a p-type cladding layer 54 are sequentially stacked on an n-type semiconductor substrate 51 (the downward direction in FIG. 2 is the stacking direction). It has a laminated structure. On the p-type cladding layer 54, a p-type ridge 55 and an n-type current blocking layer 56 formed so as to fill the step between the p-type ridge 55 are formed. A p-type contact layer 57 and a p-side electrode 58 are laminated on 56. An n-side electrode 59 is formed on the surface opposite to the stacking direction of the n-type semiconductor substrate 51.
An insulating layer 60 that electrically insulates the third semiconductor laser element 50 and the heat dissipation material 42 is formed on the surface of the third semiconductor laser element 50 that contacts the heat dissipation material 42.
Then, by flowing a predetermined current from an external power source toward the n-side electrode 59 from the p-side electrode 58, a laser beam having an oscillation wavelength of 650 nm band from the light emitting region corresponding to the p-type ridge 55 of the active layer 53. L50 is emitted.
By the way, the n-type current block layer 56 is provided so that a current applied from an external power source flows intensively in the p-type ridge 55 without flowing into the n-type current block layer 56.

In the fourth semiconductor laser element 70, an n-type cladding layer 72, an active layer 73, and a p-type cladding layer 74 are sequentially stacked on an n-type semiconductor substrate 71 (the downward direction in FIG. 2 is the stacking direction). It has a laminated structure. On the p-type cladding layer 74, an n-type current blocking layer 76 is formed so as to fill the step between the p-type ridge 75 and the p-type ridge 75, and on the p-type ridge 75 and the n-type current blocking layer 76. The p-type contact layer 77 and the p-side electrode 78 are stacked. An n-side electrode 79 is formed on the surface opposite to the stacking direction of the n-type semiconductor substrate 71.
An insulating layer 80 that electrically insulates the fourth semiconductor laser element 70 and the heat dissipation material 42 is formed on the surface of the fourth semiconductor laser element 70 that contacts the heat dissipation material 42.
Then, by flowing a predetermined current from an external power source toward the n-side electrode 79 from the p-side electrode 78, laser light having an oscillation wavelength of 780 nm band from the light emitting region corresponding to the p-type ridge 75 in the active layer 73. L70 is emitted.
Similarly, the n-type current blocking layer 76 is provided so that a current applied from an external power supply flows intensively to the p-type ridge 75 without flowing to the n-type current blocking layer 76.

Further, the p-type ridge 55 and the p-type ridge 75 are provided so as to be offset in a direction approaching each other.
By providing the p-type ridge 55 and the p-type ridge 75 so as to be offset from each other in a direction approaching each other, the light emitting region of the third semiconductor laser element 50 and the light emitting region of the fourth semiconductor laser element 70 are brought close to each other. Therefore, when information is recorded on and reproduced from the optical disk using the optical pickup 90, the optical paths of the laser beams of the semiconductor laser elements 50 and 70 irradiated onto the optical disk can be made closer to each other. For this reason, since a common optical system can be used, the number of parts can be reduced.

The third semiconductor laser element 50 and the fourth semiconductor laser element 70 can be manufactured using a known semiconductor process.
In the second embodiment, the insulating layer 60 and the insulating layer 80 are formed by depositing silicon nitride (SiN) using a sputtering method.
In the second embodiment, the thickness of the insulating layer 60 and the insulating layer 80 is 100 mm.

The submount 41 has a function of efficiently dissipating heat generated from the element driven when the third semiconductor laser element 50 or the fourth semiconductor laser element 70 is driven. It is preferable to use a large material. Silicon (Si), copper (Cu), aluminum nitride (AlN), or the like can be used as a material having high thermal conductivity.
In the second embodiment, the submount 41 was obtained by cutting a silicon wafer into a predetermined dimension.

Further, the heat radiation member 42 is made of a material having a higher thermal conductivity than air, thereby driving heat generated from the element driven when the third semiconductor laser element 50 or the fourth semiconductor laser element 70 is driven. It is possible to efficiently dissipate heat to other elements that do not.
Since the third semiconductor laser element 50, the fourth semiconductor laser element 70, and the heat dissipation material 42 are electrically insulated by the insulating layers 60 and 80, respectively, the heat dissipation material 42 has a higher thermal conductivity than air. Any material may be an insulating material or a conductive material.
In the second embodiment, gold (Au) is used as the heat dissipation material 42.

  The embodiment of the present invention is not limited to the configuration and procedure described above, and it goes without saying that modifications may be made without departing from the scope of the present invention.

For example, in the first embodiment, the first semiconductor laser element 10 is a DVD light source and the second semiconductor laser element 20 is a CD light source. However, the present invention is not limited to this, and the first semiconductor laser is used. The element 10 may be a CDCD light source, the second semiconductor laser element 20 may be a CD light source, and at least one of the first semiconductor laser element 10 and the second semiconductor laser element 20 may be another optical disk light source. It is good.
Similarly, in the second embodiment, the third semiconductor laser element 50 is a DVD light source and the fourth semiconductor laser element 70 is a CD light source. However, the present invention is not limited to this. The third semiconductor The laser element 50 may be a CD light source, the fourth semiconductor laser element 70 may be a DVD light source, and at least one of the third semiconductor laser element 50 and the fourth semiconductor laser element 70 is for another optical disk. A light source may be used.

Here, a modification of the first embodiment will be described with reference to FIG.
FIG. 3 is a schematic perspective view for explaining a modification of the first embodiment.
As shown in FIG. 3, even when the opposing surfaces of the first semiconductor laser element 10a and the second semiconductor laser element 20 are substantially parallel to each other, the first semiconductor laser element 10a and the second semiconductor laser element 10a By filling the predetermined gap D1a with the semiconductor laser element 20 with the heat dissipating material 2, the same effect as in the first embodiment can be obtained.

In the first and second embodiments and the modification, the predetermined gaps D1, D2, and D1a are filled with the heat radiating materials 2 and 42. However, the present invention is not limited to this.
By connecting adjacent semiconductor laser elements through at least a heat dissipation material, the same effects as those of the first and second embodiments and the modification can be obtained, but the contact area between each semiconductor laser element and the heat dissipation material can be obtained. Since the heat radiation effect can be obtained more as the value is larger, it is desirable to fill a predetermined gap with a heat radiating material as in the first and second embodiments and modifications.

  Moreover, each layer structure of the 1st-4th semiconductor laser element 10, 10a, 20, 50, 70 shown by the 1st-2nd Example and the modification is an example, and is not limited to this. .

  In the first and second embodiments, the optical pickup has been described as an example of the laser device. However, the present invention is not limited to this, and the present invention is applied to all laser devices having a plurality of light sources. be able to.

It is a typical perspective view for demonstrating the 1st Example of the laser apparatus of this invention. It is a typical perspective view for demonstrating 2nd Example of the laser apparatus of this invention. It is a typical perspective view for demonstrating the modification of the laser apparatus of this invention.

Explanation of symbols

1, 41 submount, 2, 42 heat dissipation material, 10, 20, 50, 70 semiconductor laser element, 11, 21, 51, 71 n-type semiconductor substrate, 12, 22, 52, 72 n-type cladding layer, 13, 23 , 53, 73 active layer, 14, 24, 54, 74 p-type cladding layer, 15, 25, 55, 75 p-type ridge, 16, 26, 56, 76 n-type current blocking layer, 17, 27, 57, 77 Contact layer, 18, 28, 58, 78 p-side electrode, 19, 29, 59, 79 n-side electrode, 30, 90 optical pickup, 60, 80 insulating layer, D1, D2 predetermined gap, L10, L20, L50, L70 laser light

Claims (2)

The base,
Two semiconductor laser elements fixed on the base with a predetermined gap;
It is made of an insulating material having a thermal conductivity larger than that of air, and a heat conducting part that connects the two semiconductor laser elements;
A laser device comprising: The base,
Two semiconductor laser elements fixed on the base with a predetermined gap;
Made of a material having a higher thermal conductivity than air, and a heat conductive portion for connecting the two semiconductor laser elements;
Have
The two semiconductor laser elements each have an insulating layer on the predetermined gap side,
The laser device characterized in that the heat conducting section connects the two semiconductor laser elements through the insulating layers.

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