JP3074092B2 - Semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device mainly used for an optical disk pickup or a light source for optical communication.

[0002]

2. Description of the Related Art Conventionally, there is a so-called unit type semiconductor laser device as shown in FIGS. FIG. 12 is a vertical sectional view at the center, and FIG. 13 is an external view of the protective resin layer removed.

[0003] At the center of one end of a substrate 62 formed by applying nickel plating and gold plating on the surface of an aluminum plate,
The submount 63 is mounted and fixed by a connection material such as indium. The submount 63 is basically made of a rectangular material made of silicon, and has aluminum wirings 65 and 66 formed on its surface. The aluminum wiring 65 is a wiring for supplying power to the laser diode chip 69 via the silicon dioxide film 64. The aluminum wiring 66 is a wiring for taking out a current generated in the submount 63 by the operation of the monitor element 67 described later in detail.

The aluminum wiring 65 provided at the center on the submount 63 forms a bonding surface, on which a laser diode chip 69 is bonded by a conductive brazing material 70. The two laser light emitting end faces 69a and 69b of the laser diode chip 69 are installed so as to face outward and inward, respectively. Further, a monitor element 67 is integrally formed at a position adjacent to the laser light emitting end face 69b on the inner side of the laser diode chip 69 at the center of the surface of the submount 63. This monitor element 67
Is formed of a photodiode element in which a P-type impurity is diffused from the surface of the submount 63 to form a PN junction, and the aluminum wiring 66 is connected to the photodiode element.

[0005] The aluminum wirings 65 and 66 are connected to corresponding leads 71a and 71b formed on a flexible circuit 71 connected to the substrate 62 by wires W1 and W, respectively.
2 is wire-bonded. The negative electrode of the laser diode chip 69 is electrically connected to the substrate 62 by opening the silicon dioxide film 64 on the submount 63 and wire-bonding it to the pad 68 that is internally conductive with the wire W4. Further, the substrate 62 is wire-bonded to the leads 71c of the flexible circuit 71 by wires W3.

The laser diode chip 69 is covered with a transparent resin 72. The transparent resin 72 is provided on the laser light emitting end surface 69 a outside the laser diode chip 69.
Not only coat the laser diode chip 69
To form a solid waveguide 72a connecting the inner laser light emitting end face 69b and the monitor element 67.

As the transparent resin 72, an epoxy resin, a silicon resin, or the like is used. These resins are made into a liquid state and adhere to the laser diode chip 69. Then, this liquid resin is applied to the outer laser light emitting end face 69.
In a, a flat surface is formed by the surface tension. Then, when the resin is cured in this state, the resin is cured while the flatness of the resin surface is maintained on the outer laser beam emitting end surface 69a side, and a flat emitting surface is formed.

Further, the laser diode chip 69
Submount 6 to which the monitor element 67 is bonded
The entire area from 3 to the end of the flexible circuit 71 is sealed with the protective resin layer 73, and the submount 63, the wires W1 to W4, and the like are covered and protected.

[0009]

However, the above-described conventional semiconductor laser device has the following problems. That is, the thickness of the transparent resin 72 covering the outer laser light emitting end surface 69a of the laser diode chip 69 cannot be particularly defined. However, the transparent resin 7
When the thickness of the laser diode 2 is increased, the laser light emission characteristics are disturbed due to the multiple reflection between the outer laser light emitting end surface 69a of the laser diode chip 69 and the surface of the transparent resin 72, and the light source is used as an optical disk light source There is a problem that it cannot be used.

FIG. 14 shows the laser diode chip 6.
9, the thickness of the transparent resin 72 (hereinafter, simply referred to as resin thickness) coated on the outer laser light emitting end surface 69a is 1000
An example of a laser light emission characteristic in the case of μm is shown. In this case, the single peak of the laser light is lost due to multiple reflection between the outer laser light emitting end surface 69a of the laser diode chip 69 and the surface of the transparent resin 72, and the laser light cannot be used as a light source for an optical disk. There is a problem that there is. Here, “θ‖” is the intensity distribution in the horizontal direction with respect to the active layer, and “θ⊥” is the intensity distribution in the vertical direction.

Further, when the state of application of the transparent resin 72 is not parallel to the outer laser beam emitting end surface 69a, there is a problem that the optical axis is shifted due to a lens effect or the like.

FIG. 15 shows an example of laser light emission characteristics when the surface state of the transparent resin 72 is not parallel to the outer laser light emission end surface 69a of the laser diode chip 69. As is clear from FIG. 15, the optical axis shift is so large that it cannot be used as an optical disk light source.

Further, the outer laser light emitting end surface 69a of the laser diode chip 69 is made of a transparent resin
In the case where the resin thickness at the time of coating with 2 is 500 μm or more, it is conceivable that the transparent resin 72 is composed of two different resins for the purpose of stress relaxation. However, laser light causes multiple reflections at the interface between the resins, and cannot be used as a light source for optical disks.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser device which can be used as a light source for an optical disk without losing unimodal laser light emission characteristics or causing an optical axis shift. .

[0015]

To achieve the above object, according to an aspect of the first invention, a semiconductor laser chip mounted on the base is a semiconductor laser device comprising be coated with an trees fat,
At least one type of resin covers the base including the semiconductor laser chip, and the thickness is 500 μm or less.
In addition, it has a substantially uniform thickness, and its surface is parallel to the laser light emitting end face on the outer side.

According to a second aspect, in the semiconductor laser device of the first aspect, the base is a stem, and a monitoring photodiode is mounted on the stem inside the semiconductor laser chip. Features.

According to a third aspect, in the semiconductor laser device according to the first aspect, the base is a lead frame, and the semiconductor laser chip is mounted on a lead of the lead frame via a submount. A monitoring photodiode is mounted on the lead inside the semiconductor laser chip, and the direction of extension of the light receiving surface of the monitoring photodiode is perpendicular to the laser light emitting end face inside the semiconductor laser chip. It is characterized by:

According to a fourth aspect of the present invention, in the semiconductor laser device of the first aspect, the base is a lead frame, and the mounting position of the monitoring photodiode on the lead inside the semiconductor laser chip is the semiconductor laser. The laser light emitting end surface inside the chip is inclined in a desired direction, and a monitoring photodiode is mounted on the inclined surface.

According to a fifth aspect of the present invention, in the semiconductor laser device of the first aspect, the base is a lead frame, and a recess is formed in the lead inside the semiconductor laser chip, and a monitor is provided in the recess. A photodiode is mounted, and the direction in which the light receiving surface of the monitoring photodiode extends is perpendicular to the laser light emitting end face inside the semiconductor laser chip.

[0020]

According to the first aspect of the present invention, the laser light is emitted from the outer laser light emitting end face of the semiconductor laser chip mounted on the base and covered with one kind of resin to have a substantially uniform thickness. At this time, the thickness of the resin covering the outer laser light emitting end face of the semiconductor laser chip is 500 μm or less. Therefore, there is no influence of the multiple reflection on the emitted laser light, and the single-peak property is not lost in the laser light emission characteristics.
Further, the surface of the resin covering the outer laser light emitting end face is parallel to the outer laser light emitting end face. Therefore, there is no lens effect or the like for the emitted laser light, and the optical axis does not shift in the laser light emission characteristics.

In the second invention, laser light is emitted from the outer laser light emitting end face and the inner laser light emitting end face of the semiconductor laser chip mounted on the stem and covered with one type of resin. The laser light emitted from the inner laser light emitting end face is incident on a monitoring photodiode mounted on the stem inside the semiconductor laser chip, and the power of the laser light is monitored. At this time, the thickness of the resin covering the outer laser light emitting end face of the semiconductor laser chip is 500 μm or less, and the surface of the resin is parallel to the outer laser light emitting end face. . Therefore, the laser light emitted outward from the outer laser light emission end face does not lose its single-peak property and the optical axis does not shift.

In the third invention, the laser beam emitted from the outer laser beam emitting end face of the semiconductor laser chip mounted on the lead of the lead frame via the submount and covered with one kind of resin is Since the thickness of the resin is 500 μm or less with respect to the outer laser light emitting end face and its surface is parallel, the single-peak property is not lost and the optical axis is not shifted. On the other hand, the laser light emitted from the inner laser light emitting end face is incident on a monitoring photodiode mounted on the lead inside the semiconductor laser chip, and the power and the like of the laser light are monitored.

According to the fourth aspect of the present invention, the resin mounted on the lead of the lead frame and having a resin thickness of 5
The laser light emitted from the outer laser light emitting end face of the semiconductor laser chip coated in parallel with a thickness of not more than 00 μm does not lose its single-peak property or shift its optical axis. On the other hand, the laser light emitted from the inner laser light emitting end face is a monitoring photodiode mounted on an inclined surface of the lead in which the inner laser light emitting end face is inclined in a desired direction inside the semiconductor laser chip. And the power of the laser beam is monitored better.

According to the fifth aspect of the present invention, a resin having a resin thickness of 5
The laser light emitted from the outer laser light emitting end face of the semiconductor laser chip coated in parallel with a thickness of not more than 00 μm does not lose its single-peak property or shift its optical axis. On the other hand, the laser light emitted from the inner laser light emitting end face is incident on a monitoring photodiode mounted in a recess formed in the lead inside the semiconductor laser chip, and the power of the laser light and the like is increased. Well monitored.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a sectional view of the semiconductor laser device of the first embodiment. In the present embodiment, a laser diode chip 1 is die-bonded to one outer end on a stem 3 (or a lead frame).

The resin 2 covers the one end surface of the stem 3 to the upper surface of the stem 3 covering the surface of the laser diode chip 1. At this time, the resin 2 is provided on an outer laser light emitting end face (hereinafter referred to as a forward laser light emitting end face) 1 of the laser diode chip 1.
With respect to a, the resin is coated so that the resin thickness is 500 μm or less and its surface is parallel. In addition, as the resin 2, one kind of transparent resin made of silicon resin or polyimide resin is used.

FIG. 2 is a sectional view of a semiconductor laser device according to a second embodiment. In this embodiment, the tip of the stem 13 having a T-shaped cross section, which corresponds to the vertical bar of the "T", is formed such that the end face of the tip and the front laser beam emitting end face 11a are flush with each other. The laser diode chip 11 is die-bonded. Also, stem 1
In the vicinity of the intersection of the portion corresponding to the horizontal bar of the "T" with the portion corresponding to the vertical bar in FIG.
Is die bonded.

Also in the case of the present embodiment, the laser diode chip 11 and the monitoring photodiode 15 are covered from the end face of the stem 13 corresponding to the vertical bar of the "T", and the stem 13 extends horizontally. The portion corresponding to the rod is covered with the resin 2. Also at this time, the resin 2 is coated so that the resin thickness is 500 μm or less and parallel to the front emission end face 11 a of the laser diode chip 11.

FIGS. 3 and 4 show a semiconductor laser device according to a third embodiment. In this embodiment, the laser diode chip 21 and the monitoring photodiode 25 are mounted on the lead 24 to improve the productivity. At this time, the laser diode chip 21 is die-bonded via the submount 26 in consideration of the amount of incidence on the monitoring photodiode 25. Incidentally, 21a
Is a front laser light emitting end face of the laser diode chip 21, and 28 is a tie bar.

In the semiconductor laser device shown in FIG. 3, leads of insert type lead frames 24 and 27 (in which a lead frame and a holding member 27 made of plastic or the like are integrally formed) are connected via a submount 26 to the leads. The laser chip 21 and the monitoring photodiode 25 are mounted. Although omitted in the figure,
The resin is coated so that the resin thickness is 500 μm or less and the surface is parallel to the front laser light emitting end face 21 a of the laser diode chip 21.

On the other hand, in the semiconductor laser device shown in FIG.
The laser diode chip 21 and the monitoring photodiode 25 are mounted on the lead 24 from which the tie bar has been cut. Then, the laser diode chip 21
The resin 2 is coated so that the resin thickness is not more than 500 μm and the surface is parallel to the front laser light emitting end face 21a in the above.

A structure in which the monitoring photodiode 25 and the submount 26 are integrated is also possible.

FIGS. 5 and 6 show a semiconductor laser device according to a fourth embodiment. In the semiconductor laser device shown in FIG. 5, the position where the monitoring photodiode 35 is die-bonded at the tip of the lead 34 is processed into a V-shape by punching, and the upper surface of the lead 34 outside the punched V-shaped recess 39 is formed. Laser diode chip 3
On the other hand, a monitoring photodiode 35 is die-bonded on the inner slope of the recess 39 in hope of the laser diode chip 31.

The resin 2 is coated so that the resin thickness is 500 μm or less and the surface is parallel to the front laser light emitting end face 31a of the laser diode chip. FIG. 6 is a diagram showing the shape of the lead frame in FIG. Note that 37 is a holding member, and 38 is a tie bar.

As described above, in the present embodiment, the monitoring photodiode 35 is die-bonded on the slope inside the punched V-shaped recess 39 at the tip of the lead 34 in the hope of the laser diode chip 31. Therefore, the laser light from the laser diode chip 31 is easily incident on the monitoring photodiode 35. Therefore, a submount as in the case of the third embodiment is unnecessary.

FIGS. 7 and 8 are views showing a semiconductor laser device according to the fifth embodiment. In this embodiment, the homing process is performed so that the portion of the lead 44 where the monitoring photodiode 45 is installed faces outward. Thus, the amount of light incident on the monitoring photodiode 45 from the laser diode chip 41 mounted on the leading end of the lead 44 is improved. FIG. 7 shows a state before the portion of the semiconductor laser chip 41 is covered with a resin. Also in this embodiment, when the laser diode chip 41 is covered with resin, the resin thickness is not more than 500 μm with respect to the front laser light emitting end face 41a of the laser diode chip 41 and the surface is parallel. It is coated. FIG. 8 is a diagram showing the shape of the lead frame. Incidentally, 47 is a holding member, and 48 is a tie bar.

FIGS. 9 and 10 show a semiconductor laser device according to a sixth embodiment. In the present embodiment, the tip of the lead 54 is bent in a U-shape to form a concave portion 59, and the monitoring photodiode 55 is mounted in the concave portion 59. Thus, the monitoring photodiode 55
Is parallel to the mounting surface of the laser diode chip 51, and the laser light from the laser diode chip 51 can be incident on the monitoring photodiode 45. FIG. 9 shows a state before the portion of the laser diode chip 51 is covered with a resin. Also in this embodiment, when coating the laser diode chip 51 with resin, the laser diode chip 51 is coated so that the resin thickness is 500 μm or less and parallel to the front laser light emitting end face 51a of the laser diode chip 51. FIG. 10 is a diagram showing the shape of the lead frame. Incidentally, 57 is a holding member, and 58 is a tie bar.

FIG. 11 shows that, as shown in each of the above embodiments, the resin thickness is 500 μm or less with respect to the front laser light emitting end face of the laser diode chip, and the surface is parallel. 1 shows an example of a laser light emission characteristic of a semiconductor laser device covered with. As can be seen from FIG. 11, since the front emission end face of the semiconductor laser chip is covered with one kind of resin with a resin thickness of 500 μm, the light intensity distribution “θ‖” in the horizontal direction with respect to the active layer for laser oscillation. Also, the light intensity distribution “θ⊥” in the direction perpendicular to the active layer has a single-peak characteristic. Further, since the surface of the resin covering the front emission end face of the semiconductor laser chip is parallel to the front emission end face, both of the light intensity distributions have a characteristic that the optical axis is not shifted. .

That is, according to each of the above embodiments, it is possible to provide a semiconductor laser device that can be used as a light source for an optical disk.

The resin thickness may be 500 μm or less. For example, the resin thickness is 400 μm, 300 μm, 200 μm.
Good characteristics are obtained even in the case of μm and 100 μm. However, if the thickness of the resin is too small, corrosion of the end face occurs due to ambient humidity, and deterioration occurs. Therefore, a large fluctuation occurs in the operating current of the laser, which causes a problem in the reliability of the laser.

[0041]

As is clear from the above description, in the semiconductor laser device of the first invention, the outer laser light emitting end face of the semiconductor laser chip is made of one kind of resin with a resin thickness of 50%.
Since the surface is coated so as to be parallel at 0 μm or less, the laser light emitted from the outer laser light emission end face has a laser light emission characteristic in which monomodality is not lost or the optical axis is not shifted. . Therefore, according to the present invention, a semiconductor laser device that can be used as a light source for an optical disk can be provided.

Further, a semiconductor laser device according to a second aspect of the present invention
Since the monitoring photodiode is mounted on the stem inside the semiconductor laser chip, the power and the like of the laser light emitted from the semiconductor laser chip can be monitored by the monitoring photodiode. Therefore, according to the present invention, it is possible to monitor the laser light having the laser light emission characteristic without losing the single-peak property in the laser light emission characteristic or causing a shift in the optical axis.

The semiconductor laser device according to the third aspect of the present invention
The semiconductor laser chip is mounted on a lead via a submount, and a monitoring photodiode is mounted on the lead inside the semiconductor laser chip, and the extending direction of the light receiving surface of the monitoring photodiode is set to the semiconductor laser chip. The monitor photodiode can easily receive laser light from the inner laser light emitting end face of the semiconductor laser chip because the laser light is directed perpendicular to the inner laser light emitting end face of the semiconductor laser chip. Therefore, according to the present invention, it is possible to reliably monitor the power and the like of the laser light having the laser light emission characteristics without losing the single-peak property in the laser light emission characteristics or causing a shift in the optical axis.

A semiconductor laser device according to a fourth aspect of the present invention comprises:
Since the mounting position of the monitoring photodiode on the lead inside the semiconductor laser chip is inclined in the direction in which the laser light emitting end face inside the semiconductor laser chip is desired, the monitoring photodiode mounted on the inclined surface Can reliably receive laser light from the inner laser light emitting end face of the semiconductor laser chip. Therefore, according to the present invention, it is possible to more reliably monitor the power and the like of the laser light having the laser light emission characteristics without losing the single-peak property of the laser light emission characteristics or causing a shift in the optical axis.

A semiconductor laser device according to a fifth aspect of the present invention comprises:
A monitoring photodiode is mounted in a recess formed in a lead inside the semiconductor laser chip, and a light receiving surface of the monitoring photodiode extends in a direction perpendicular to an inner laser light emitting end face of the semiconductor laser chip. Since the direction is set to the direction, the monitoring photodiode can easily receive laser light from the laser light emitting end face inside the semiconductor laser chip. Therefore, according to the present invention, it is possible to reliably monitor the power and the like of the laser light having the laser light emission characteristics without losing the single-peak property in the laser light emission characteristics or causing a shift in the optical axis.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a semiconductor laser device according to a second embodiment.

FIG. 3 is a plan view of a semiconductor laser device according to a third embodiment.

FIG. 4 is a longitudinal sectional view of a semiconductor laser device according to a third embodiment, which is different from FIG. 3;

FIG. 5 is a perspective view of a semiconductor laser device according to a fourth embodiment.

FIG. 6 is a view showing a lead frame shape in FIG. 5;

FIG. 7 is a perspective view of a semiconductor laser device according to a fifth embodiment.

FIG. 8 is a view showing a lead frame shape in FIG. 7;

FIG. 9 is a perspective view of a semiconductor laser device according to a sixth embodiment.

FIG. 10 is a view showing a lead frame shape in FIG. 9;

FIG. 11 is a diagram showing an example of laser light emission characteristics of the semiconductor laser device of the present invention.

FIG. 12 is a longitudinal sectional view of a conventional semiconductor laser device.

13 is an external view of the semiconductor laser device shown in FIG.

FIG. 14 is a diagram illustrating an example of laser light emission characteristics in a semiconductor laser device in which a resin thickness with respect to a front emission end face of a semiconductor laser chip is 1000 μm.

FIG. 15 is a diagram illustrating an example of laser light emission characteristics in a semiconductor laser device in which a resin coating shape is not parallel to a front emission end face of a semiconductor laser chip.

[Explanation of symbols]

1,11,21,31,41,51 ... laser diode chip, 1a, 11a, 21a, 31a, 41a, 51a ... front laser light emitting end face, 2 ... resin, 3,13 ... stem, 4,24,34, 44, 54 ... lead, 15, 25, 35, 45, 55 ... monitor photodiode, 26 ... submount, 27, 37, 47, 57 ... holding member, 28, 38, 48, 58 ... tie bar.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-125688 (JP, A) JP-A-2-159084 (JP, A) JP-A-63-136684 (JP, A) JP-A-4- 48674 (JP, A) JP-A-5-63309 (JP, A) JP-A-4-280487 (JP, A) JP-A-3-53858 (JP, U) (58) Fields investigated (Int. ⁷ , DB name) H01S 3/18

Claims (5)

(57) [Claims] 1. A semiconductor laser chip mounted on the base a semiconductor laser over laser device comprising be coated with an resin, the resin coating the base comprising at least the semiconductor laser chip is one type, the The thickness is less than 500μm
A semiconductor laser device having a substantially uniform thickness and a surface parallel to the outer laser light emitting end face. 2. The semiconductor laser device according to claim 1, wherein said base is a stem, and a monitoring photodiode is mounted on said stem inside said semiconductor laser chip. apparatus. 3. The semiconductor laser device according to claim 1, wherein the base is a lead frame, and the semiconductor laser chip is mounted on a lead of the lead frame via a submount. A monitor photodiode is mounted on the lead inside the chip, and the direction of extension of the light receiving surface of the monitor photodiode is perpendicular to the laser light emitting end face inside the semiconductor laser chip. Semiconductor laser equipment. 4. The semiconductor laser device according to claim 1, wherein the base is a lead frame, and a mounting position of a monitor photodiode on a lead inside the semiconductor laser chip is a laser inside the semiconductor laser chip. A semiconductor laser device having a light emitting end face inclined in a desired direction, and a monitoring photodiode mounted on the inclined face. 5. The semiconductor laser device according to claim 1, wherein the base is a lead frame, and a recess is formed in the lead inside the semiconductor laser chip, and a monitoring photodiode is mounted in the recess. The semiconductor laser device is characterized in that the direction of extension of the light receiving surface of the monitoring photodiode is perpendicular to the laser light emitting end face inside the semiconductor laser chip.