JP3582173B2 - Semiconductor laser device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor laser device capable of obtaining high-power laser light, and more particularly to a semiconductor laser device for distance measurement that constitutes a robot eye, a laser radar system, or the like. Things.
[0002]
[Prior art]
In a semiconductor laser, the connection between the upper electrode of the element and the lead of the stem is made by wire bonding. Usually, in the case of a single stripe electrode structure, it is configured as shown in FIG. 5A or FIG. 5B.
[0003]
Referring to FIG. 5A, a semiconductor laser device 3 having a predetermined stripe width is bonded on a heat sink 2 provided on a stem 1. The semiconductor laser device 3 is connected to a drive circuit 7 via a wire 4 bonded to the center of a stripe-shaped electrode, a stem lead 5, and a stem lead 6.
[0004]
Further, in the semiconductor laser device having the structure shown in FIG. 5B, wires 4a and 4b are bonded to two places on the left and right outside the active layer region in order to avoid damage to the active layer of the semiconductor laser element 3. ing.
[0005]
However, in each of the semiconductor laser devices shown in FIGS. 5A and 5B, only one drive circuit is provided for one laser element. Then, even in the case of the semiconductor laser device having the configuration shown in FIG. 5B, current flows evenly through the left and right wires 4a and 4b.
[0006]
As means for deflecting the laser beam, a semiconductor laser having two independent injection electrodes is conventionally formed as disclosed in, for example, Japanese Patent Publication No. 1-22753, and the laser beam is applied to the two electrodes. A technique for deflecting a beam by changing the current ratio to be injected has been proposed.
[0007]
[Problems to be solved by the invention]
However, in the case of a semiconductor laser device having one drive circuit for one semiconductor laser element as shown in FIGS. 5A and 5B, the beam of the laser is deflected. It couldn't be done. Further, in the technique disclosed in Japanese Patent Publication No. 1-22753, two injection electrodes must be formed for one laser element, and the process and the element structure become complicated. Had.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor laser device capable of deflecting a beam without forming two injection electrodes for one laser element. is there.
[0009]
[Means for Solving the Problems]
The present inventors have found that the horizontal beam shape is related to the current distribution in the horizontal direction due to the resistance component of the upper electrode. In particular, it has been found that this tendency appears strongly in a semiconductor laser having a stripe width of 100 μm or more used as a high-output pulse laser.
[0010]
Therefore, the invention according to claim 1, a plurality of semiconductor laser including an active layer on a semiconductor substrate - are stacked The components, semiconductor laser having one upper electrode of the stripe structure - The a, the semiconductor laser A current supply means connected to the current supply means, and a drive means connected to the current supply means and supplying a drive current to the semiconductor laser to cause the semiconductor laser to emit light. Comprises first and second current supply means connected to two positions at both ends parallel to the cleavage plane with respect to the light emitting surface of the stripe structure of the upper electrode, and the driving means comprises the first and second current supply means. And first and second drive means connected to the second current supply means and independently supplying a drive current to the semiconductor laser.
[0011]
According to a second aspect of the present invention, in the first aspect, a stripe width of a light emitting region in the active layer is 100 μm or more.
[0012]
Further, the invention according to claim 3 is characterized in that, in the invention according to claims 1 and 2, the stripe electrode is made of Cr / Au.
[0013]
According to the first aspect of the present invention, the current flowing through the wires connected to the two positions at both ends parallel to the cleavage plane is independently controlled with respect to the light emitting surface of the stripe structure of the upper electrode. , Beam deflection can be controlled. As shown in FIGS. 3B and 3C, when the currents flowing through the two wires are made asymmetric, the injection current density in the active layer can be inclined by the resistance component of the upper electrode, and the horizontal beam shape can be obtained. Is deflected to the lower density side of the current density distribution.
[0014]
According to the second aspect of the present invention, it is possible to apply the present invention to a high-power semiconductor laser having an optical output of several tens of watts in pulse driving. Further, the current density distribution becomes more remarkable due to the wide stripe width, and the deflection of the horizontal beam can be increased.
[0015]
According to the third aspect of the present invention, the sheet resistance can be controlled by the conditions of the heat treatment of the Cr / Au electrode. Here, if the sheet resistance value is relatively large, for example, about 150 to 200 mΩ / □, as shown in FIG. 3A, even when the current flows evenly through the two wires. Then, the current density distribution in the active layer is inclined, and the current density in the central portion is reduced. In such a state, when the value of the current flowing through the two wires is changed, the deflection of the horizontal beam occurs more remarkably. Thus, by controlling the sheet resistance value, the degree of beam deflection can be controlled.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
1 and 2 show a first embodiment of the present invention. FIG. 1 is a configuration diagram of a high-power beam deflecting semiconductor laser device, and FIG. 2 is a diagram of the semiconductor laser of FIG. It is sectional drawing seen from the light emitting surface.
[0018]
1 and 2, a stem 10 is provided with a copper heat sink 11 having a gold-plated surface. Then, a semiconductor laser element 12 having a predetermined stripe width is bonded on the heat sink 11 using a bonding material 13.
[0019]
The semiconductor laser element 12 is formed by forming a lower electrode 14, a clad layer 15, an active layer (light emitting layer) 16, a clad layer 17, an insulating film 18, and an upper electrode 19 on a bonding material 13. . In order to supply an external electrode to the semiconductor laser element 12, gold wires 20a and 20b are bonded to two ends of the upper electrode 19 having a stripe structure parallel to the cleavage plane. They are electrically connected to stem leads 21 and 22, respectively. The lower electrode 14 is electrically connected to the stem lead 23 through the heat sink 11.
[0020]
The above-mentioned semiconductor laser is usually manufactured by a well-known method for manufacturing a semiconductor laser device. That is, as described above, after laminating a plurality of semiconductor laser components including an active layer on a semiconductor substrate, an upper electrode 19 and a lower electrode 14 are formed above and below the element, and the It is joined using the material 13. Note that the present inventors used Au / Sn solder produced by electron beam evaporation as the bonding material 13.
[0021]
The semiconductor laser element 12 is bonded to the heat sink 12 by melting the bonding material 13 at a temperature of about 400 ° C. using a die bonding apparatus. Thereafter, wires 20a and 20b are bonded to the left and right two places outside the stripe electrode region of the upper electrode 19 of the semiconductor laser element 12 by a wire bonding apparatus, and the other is bonded to stem leads 21 and 22, respectively. Is done.
[0022]
A drive circuit 24 for causing the semiconductor laser element 12 to emit light is electrically connected to the stem leads 21 and 23. Similarly, a drive circuit 25 is electrically connected to the stem leads 22 and 23. By using these two drive circuits 24 and 25 to supply currents to the left and right wires 20a and 20b independently, the beam can be deflected.
[0023]
In this semiconductor laser device, when the drive circuits 24 and 25 uniformly supply current to the left and right wires 20a and 20b, the beam becomes symmetric as shown in FIG. . Here, Cr / Au is used as the upper electrode 19, but with this metal, the sheet resistance can be changed to 50 to 200 mΩ / □ depending on the conditions of the heat treatment.
[0024]
For example, under a heat treatment condition of 360 ° C. for 2 minutes, the sheet resistance value can be increased to about 150 to 200 mΩ / □, the current density distribution is not uniform, and the current density in the central portion of the element decreases. Reflecting this, the horizontal beam shape has a bimodal shape with a concave center.
[0025]
Next, a case is considered in which the current values flowing through the left and right wires 20a and 20b are asymmetric. The drive circuits 24 and 25 are independently controlled to make the current flowing through the left and right wires 20a and 20b asymmetric. Then, as shown in FIGS. 3B and 3C, the current density distribution is inclined, and the beam is deflected to a lower current density. As described above, the beam can be deflected in a desired direction by controlling the left and right currents of the upper electrode 19 independently by the drive circuits 24 and 25.
[0026]
Further, a metal such as Cr / Pt / Au or Ti / Pt / Au may be used as the upper electrode. In this case, even if the heat treatment is performed, the resistance value of the electrode hardly changes and the resistance becomes low, so that the current density distribution becomes nearly uniform. Therefore, the horizontal beam shape becomes unimodal, and the degree of beam deflection is reduced.
[0027]
As described above, by changing the conditions of the heat treatment of the upper electrode, or by changing the material and thickness of the upper electrode, the resistance value of the electrode can be changed, thereby controlling the degree of beam deflection. it can.
[0028]
Next, a second embodiment of the present invention will be described.
[0029]
In the second embodiment, in order to avoid repetition of the description, the description will focus on the differences from the first embodiment.
[0030]
FIG. 4 is a sectional view of a semiconductor laser device according to the second embodiment.
[0031]
This embodiment is characterized in that the active layer 16 is formed in a mesa-shaped (trapezoidal) portion of the semiconductor laser element 12 '. In this mesa portion, a cladding layer 17 ', an insulating film 18', and an upper electrode 19 'are formed.
[0032]
Also in this case, wires 20a and 20b are bonded to two places on both left and right sides of the upper electrode 19 'having a stripe width. Then, similarly to the above-described first embodiment, the currents flowing through the wires 20a and 20b are controlled by being electrically connected to the drive circuits 24 and 25 in the configuration shown in FIG. be able to. Therefore, the beam can be deflected similarly to the first embodiment.
[0033]
Further, in the second embodiment, since the active layer 16 is formed in the mesa portion, it is possible to prevent the damage from entering the active layer 16 from the side surface when forming the device, and to improve the reliability. Can be improved.
[0034]
In the above-described embodiment, the case where Cr / Au is used as the upper electrode has been described. However, the present invention is not limited to this. For example, Cr / Pt / Au, Ti / Pt / Au, Ti / Ni / Any material such as Au may be used as long as it is normally used as a GaAs p-type electrode.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to provide a semiconductor laser capable of deflecting a beam by controlling currents independently of two wires connected to an upper electrode having a stripe structure. it can.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of the present invention and is a configuration diagram of a high-power beam deflecting semiconductor laser device.
FIG. 2 shows a first embodiment of the present invention and is a cross-sectional view of the semiconductor laser device of FIG. 1 as viewed from the light emitting surface.
FIG. 3 is a characteristic diagram for explaining a relationship between a current density distribution and horizontal beam deflection.
FIG. 4 is a sectional view of a semiconductor laser device showing a configuration of a second embodiment of the present invention.
FIG. 5 is a diagram showing a configuration of a conventional semiconductor laser device.
[Explanation of symbols]
1, 10, stem, 2, 11, heat sink, 3, 12, 12 ', semiconductor laser element, 4, 4a, 4b, 20a, 20b, wire, 5, 6, 21, 22, 23, stem lead, 7, 24, 25 drive circuit, 13 bonding material, 14 lower electrode, 15, 17, 17 'clad layer, 16 active layer (light emitting layer), 18, 18' insulating film, 19, 19 ' ... the upper electrode.

Claims (3)

A plurality of semiconductor laser including an active layer on a semiconductor substrate - The components are stacked, semiconductor laser having one upper electrode of the stripe structure - The a, a current supply means connected to the semiconductor laser, the current A driving means connected to a supply means, and a driving means for supplying a driving current to the semiconductor laser and causing the semiconductor laser to emit light,
The current supply means includes first and second current supply means connected to two places at both ends parallel to the cleavage plane with respect to the light emitting surface of the stripe structure of the upper electrode,
Wherein the driving means comprises first and second driving means connected to the first and second current supply means and supplying a driving current independently to the semiconductor laser. The equipment. 2. The semiconductor laser device according to claim 1, wherein a stripe width of a light emitting region in the active layer has a width of 100 [mu] m or more. 3. The semiconductor laser device according to claim 1, wherein said stripe electrode is made of Cr / Au.

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