JP3169917B2 - Semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser device used for optical information processing, optical measurement, optical communication and the like.

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described with reference to a sectional view shown in FIG.

In this structure, a heat sink 2 is fixed above one side surface of an element fixing base 1, a semiconductor laser chip (hereinafter referred to as a laser chip) 3 is fixed thereon, and a light emitting surface of the laser chip 3 and a heat sink 2 are fixed. The laser output light detecting photodiode 4 is mounted on the side opposite to the light emitting surface of the laser chip 3, and the signal detecting photodiode 5 is mounted on the upper surface of the element fixing base 1. Is placed.

Next, the operation of this structure will be described. The emitted light 6 emitted from the laser chip 3 to the upper side of the drawing is reflected by the object, input to the photodiode 5 for signal detection as reflected light 7, and subjected to signal processing. On the other hand, the laser light emitted from the opposite side of the emission light surface of the laser chip 3 is input to the laser output light detecting photodiode 4, and is converted into a current signal corresponding to the intensity of the laser light. This signal is fed back to the laser chip drive circuit to stably control the output of the laser light.

In this conventional configuration, the signal detecting photodiode 5 and the laser output light detecting photodiode 4 are fixed in a plane that is horizontal and nearly horizontal with respect to the element fixing base 1, while the laser chip 3 Must be fixed in a vertical plane, the assembly work efficiency is poor, and there is a major problem in alignment accuracy.

As a structure for solving this problem, there is a semiconductor laser device as shown in a sectional view of FIG.

In this structure, a V-shaped groove whose both slopes are formed by the (111) plane is formed in the (100) plane silicon substrate 8, and one of the slopes of the groove is formed by the laser emission light. The main surface of the silicon substrate 8 on the side facing the mirror surface 9 is made lower than the other main surface, and the lowered main surface of the silicon substrate intersects the slope of the V-shaped groove. The laser chip 3 is fixed so that the front end face from which the laser light of the laser chip 3 is emitted is parallel to the ridge line.

According to this structure, the light emitted in the horizontal direction from the laser chip 3 can be reflected by the reflecting mirror surface 9 and taken out substantially upward. As a result, a photodiode for signal detection (not shown) and a photodiode for laser output light detection (not shown) are connected to the silicon substrate 8.
Can be placed on the main surface, and the alignment accuracy can be improved.

[0009]

When a V-shaped groove whose slope is formed by the (111) plane is formed in the (100) plane silicon substrate 8, the reflection mirror surface 9 of the groove and the surface of the silicon substrate 8 are formed. Is about 55 °, the center axis of the emitted light is about 20 ° from the direction perpendicular to the main surface of the silicon substrate.
There was a problem of tilting.

In addition, there has been a problem that photodiodes for various uses have to be mounted on a silicon substrate, which complicates an assembling process.

[0011]

According to the semiconductor laser device of the present invention, on a (100) silicon substrate having an off angle of 5 to 15 ° with respect to the <110> direction as an axis, both slopes are (111). A) trapezoidal groove formed by the surface or a truncated quadrangular pyramid-shaped recess surrounded by four (111) surfaces, and a surface of the (111) surface whose inclination with respect to the silicon substrate surface is close to 45 °. Is a reflection mirror surface for reflecting laser light, and the semiconductor laser chip is fixed to the silicon substrate such that a front end surface of the semiconductor laser chip is parallel to an upper edge line of a surface facing the reflection mirror surface. It is.

According to this structure, since the main surface of the silicon substrate is a surface provided with an off angle of 5 to 15 degrees from the (100) plane, the trapezoidal groove or the trapezoidal groove formed by the (111) plane is formed. The angle θ between the reflecting mirror surface of the truncated quadrangular pyramid-shaped concave portion and the main surface of the silicon substrate can be in the range of 40 ° ≦ θ ≦ 50 °. Therefore, the central axis of the laser light emitted from the laser chip after being reflected by the reflection mirror surface can be made substantially perpendicular to the main surface of the silicon substrate.

In addition, a flat surface is formed at the bottom in order to make the groove trapezoidal or the truncated square pyramid, and stray light that is different from normal light emitted from the laser chip is emitted from the flat surface. Thus, the light can be reflected and separated in a direction different from the normal light. When stray light is included in the regular light, optical interference occurs and the characteristics of the optical system are significantly deteriorated.

[0014]

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

(First Embodiment) A first embodiment of a semiconductor laser device according to the present invention will be described with reference to the perspective view and the sectional view shown in FIG.

This is because a V-shaped groove in which both inclined surfaces are formed by the (111) plane on the (100) plane silicon substrate 10 having an off angle of about 10 ° with the <110> direction as the rotation axis. (Hereinafter referred to as V-grooves) 11 are formed, and of these slopes, the inclination θ with respect to the surface of the silicon substrate 10 is formed.
Is the reflection mirror surface 12, and the laser chip 13 is placed on the surface of the silicon substrate 10 so that the front end surface of the semiconductor laser chip 13 is parallel to the upper edge of the groove on the surface facing this surface. Is fixed. In addition,
A gold thin film 14 of 3000 to 5000 ° is formed on the surface of the reflection mirror surface 12, and the reflectance of the mirror is 90% or more. The laser chip 13 is fixed with a solder material so that the light emitting portion is on the lower side.

With this structure, about half of the laser light emitted from the laser chip 13 in the horizontal direction is reflected by the reflection mirror as shown by the optical path 15 and travels in the vertical or near vertical direction, and is extracted as output light. It is.

Although the V-groove has been described in the embodiment, the trapezoidal groove may be formed by flattening the apex of the V-groove.
In this case, since the stray light can be separated from the regular light, optical interference can be eliminated and the characteristics of the optical system can be improved.

The (100) plane having an off angle of about 10 ° was used as the surface of the silicon substrate.
It has an off-angle of 5 to 15 ° in actual use (10
0) plane. At this time, the inclination θ of the reflection mirror surface with respect to the surface of the silicon substrate can be kept within the range of 40 ° ≦ θ ≦ 50 °. The same can be said for the other embodiments described later.

(Embodiment 2) Next, a second embodiment of the semiconductor laser device of the present invention will be described with reference to the perspective view shown in FIG.

This is because four (1) are provided on the (100) plane silicon substrate 10 provided with the off-angle described in FIG.
11) A quadrangular pyramid-shaped concave portion 16 surrounded by a surface, and a reflection mirror for reflecting a laser beam on a surface of the four (111) surfaces which is inclined closest to 45 ° with respect to the silicon substrate surface. A laser chip 13 with respect to the upper ridge 18 of the quadrangular pyramid-shaped recess 16 on the surface facing this surface.
The laser chip 13 is fixed to the silicon substrate 10 so that the front end faces are parallel. The structures of the reflection mirror surface 17 and the laser chip 13 are as shown in FIG.

With this structure, about half of the laser light emitted in the horizontal direction from the laser chip 13 is reflected by the reflecting mirror surface 17 as shown by an optical path 19 and travels in the vertical or nearly vertical direction, and is output as light. Taken out.

Although the embodiment has been described with a quadrangular pyramid-shaped concave portion, the vertex of this concave portion may be flattened to have a truncated quadrangular pyramid shape. In this case, since the stray light can be separated from the regular light, optical interference can be eliminated and the characteristics of the optical system can be improved.

(Embodiment 3) Next, a third embodiment of the semiconductor laser device of the present invention will be described with reference to the sectional view shown in FIG.

The V-groove shown in FIG. 1 or the V-groove shown in FIG. 2 is formed on a (100) plane P-type silicon substrate 20 having an off angle of about 10 ° with the <110> direction as a rotation axis. A concave portion of a quadrangular pyramid is formed, and the surface of the V groove or the concave portion whose inclination with respect to the surface of the silicon substrate 20 is closest to 45 ° is a reflecting mirror surface 21 for reflecting a laser beam. An n-type diffusion region 22 is formed on the side 20, a silicon oxide film 23 for insulation and a gold thin film 24 are laminated on the reflection mirror surface 21, and a laser is applied to the upper edge of the surface facing the reflection mirror surface 21. Chip 13
The laser chip 13 is fixed to the silicon substrate 20 so that the front end faces are parallel.

The thickness of the gold thin film 24 is set to 500 to 100.
This is a structure in which a semi-transmissive film is set as 0 °, and a part of the laser light is incident on a photodiode constituted by the P-type silicon substrate 20 and the n-type diffusion region 22.

With this structure, a part of the laser light emitted from the laser chip 13 in the horizontal direction passes through the semi-transmissive film formed of the gold thin film 24 and enters the photodiode, and the rest is a semi-transmissive film. The reflected light travels in the vertical or nearly vertical direction as shown in the optical path 25, and is extracted as output light.

The light incident on the photodiode is converted into a current signal according to the light intensity, and this current signal is fed back to the laser chip driving circuit to be used for keeping the output of the laser light constant. You.

Embodiment 4 Next, a fourth embodiment of the semiconductor laser device of the present invention will be described with reference to the sectional view shown in FIG.

The V-groove shown in FIG. 1 or the V-groove shown in FIG. 2 is formed on a (100) plane P-type silicon substrate 20 having an off angle of about 10 ° with the <110> direction as a rotation axis. A concave portion of a quadrangular pyramid is formed, and the surface of the V groove or the concave portion whose inclination with respect to the surface of the silicon substrate 20 is closest to 45 ° is a reflecting mirror surface 21 for reflecting laser light. The laser chip 13 is positioned such that the front end face of the laser chip 13 is parallel to the upper edge line.
Are fixed to the silicon substrate 20, and an n-type diffusion region 26 is formed on the P-type silicon substrate 20 behind the laser chip 13.

P-type silicon substrate 20 and n-type diffusion region 26
Receives the laser light emitted from the rear end face of the laser chip 13 and generates a current signal converted according to the light intensity. This current signal is fed back to the laser chip driving circuit, so that the laser chip 13
It is used for monitoring to make the intensity of the laser light emitted from the front end face of the laser light constant.

The laser light emitted in the horizontal direction from the front end face of the laser chip 13 is reflected by the reflecting mirror surface 21 coated with a thin gold film, travels in a vertical or nearly vertical direction, and is extracted as output light. .

Reference numeral 27 denotes an optical path of the laser light emitted from the rear end face of the laser chip 13, and reference numeral 28 denotes an optical path of the laser light emitted from the front end face of the laser chip 13.

(Embodiment 5) Next, a fifth embodiment of the semiconductor laser device of the present invention will be described with reference to the perspective view shown in FIG.

This structure has a (100) plane P with an off angle of about 10 ° with the <110> direction as a rotation axis.
V-grooves 11 are formed on the die-shaped silicon substrate 20, the slopes of which are formed by the (111) planes on both sides. The laser chip 13 is placed on the surface of the silicon substrate 20 such that the front end face of the laser chip 13 is parallel to the upper edge of the groove on the surface facing this surface.
Are fixed, and an n-type diffusion region is formed behind the laser chip 13 to form a laser output light detection photodiode 29, and a signal detection photodiode 30 is formed on the silicon substrate 20. .

With this configuration, the laser light emitted in the horizontal direction from the front end face of the laser chip 13 is reflected by the reflecting mirror surface 12 coated with the gold thin film, and as shown in the optical path 15, in the vertical or nearly vertical direction. And the light is extracted as output light. The signal light 31 whose output light is reflected by the object is input to the signal detection photodiode 30,
The signal is processed. On the other hand, the laser light emitted from the rear end face of the laser chip 13 is input to the laser output light detecting photodiode 29 and is converted into a current signal according to the light intensity. This current signal is fed back to the laser chip drive circuit, and is used to make the output of the laser light emitted from the front end face of the laser chip constant.

According to this structure, the laser output light detecting photodiode 29 and the signal detecting photodiode 30
Are formed on the same substrate, so that they can be compactly integrated.

In the embodiment, the photodiodes for detecting the laser output light and for detecting the signal have been described. However, the present invention is not limited to this, and an amplifier circuit for a signal obtained from the photodiode, a driving circuit for a laser chip, and An optical signal processing circuit and the like can be formed over the same substrate.

[0039]

According to the semiconductor laser device of the present invention,
Using a (100) plane silicon substrate having an off angle of 5 to 15 ° with respect to the <110> direction as an axis, (11)
1) Since a trapezoidal groove or a truncated pyramid-shaped recess formed by the surface is formed, one of the (111) surfaces has an inclination of about 45 ° with respect to the surface of the silicon substrate. Plane. As a result, the laser light emitted in the horizontal direction from the laser chip is reflected by the reflection mirror surface and can be taken out substantially in the vertical direction, and the alignment in the emission direction is simplified.

Further, since the groove is trapezoidal or the recess is truncated square pyramid, a flat surface is formed at the bottom, so that stray light different from normal light emitted from the laser chip is leaked to this bottom. Because the flat surface can reflect and separate light in a direction different from that of the normal light, stray light is not included in the normal light, so that light interference is eliminated and characteristics of the optical system can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view and a sectional view of a semiconductor laser device of the present invention having a V-groove.

FIG. 2 is a perspective view of the semiconductor laser device of the present invention having a quadrangular pyramid-shaped concave portion;

FIG. 3 is a cross-sectional view of a semiconductor laser device of the present invention in which a photodiode is formed on a reflection mirror surface side.

FIG. 4 is a cross-sectional view of a semiconductor laser device of the present invention in which a photodiode is formed behind a laser chip.

FIG. 5 is a perspective view of a semiconductor laser device of the present invention in which various elements are formed on a silicon substrate on which a laser chip is mounted.

FIG. 6 is a sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a fixed base.

FIG. 7 is a sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a silicon substrate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Silicon substrate 11 V-shaped groove | channel (V groove) 12,17,21 Reflection mirror surface 13 Semiconductor laser chip 14,24 Gold thin film 15,19,25 Optical path 16 Square pyramid concave part 18 Four surfaces facing a reflection mirror surface Top ridge line of pyramidal recess 20 P-type silicon substrate 22, 26 n-type diffusion region 23 silicon oxide film 27 optical path of laser light emitted from rear end face of laser chip 28 optical path of laser light emitted from front end face of laser chip 29 laser Output light detecting photodiode 30 Signal detecting photodiode 31 Signal light

Continuation of front page (72) Inventor ▲ Yoshi ▼ Akio Kawa1-1, Sachimachi, Takatsuki-shi, Osaka Prefecture Inside Matsushita Electronics Corporation (72) Inventor Yuichi Shimizu 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics (56) References JP-A-61-42981 (JP, A) JP-A-62-23163 (JP, A) JP-A-61-153360 (JP, U) JP-A-56-96665 (JP, U) (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50 G11B 7/125 G11B 7/135

Claims (1)

(57) [Claims] 1. An angle of 5 ° to 15 ° about a <110> direction as an axis.
On a (100) silicon substrate having an off-angle of, a trapezoidal groove having slopes on both sides formed by a (111) surface or a truncated square pyramid-shaped recess surrounded by four (111) surfaces. A surface of the (111) surface, the inclination of which is close to 45 ° with respect to the surface of the silicon substrate, is defined as a reflection mirror surface for reflecting laser light, and a semiconductor laser chip is formed with respect to an upper edge of the surface facing the reflection mirror surface. Wherein the semiconductor laser chip is fixed to the silicon substrate such that front end faces thereof are substantially parallel to each other.