JP2892812B2 - Semiconductor laser device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device used for optical information processing, optical measurement, optical communication, and the like.

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 side surface of the heat sink 2 and The upper surface of the element fixing base 1 is aligned, a photodiode for detecting a laser output light 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. It is a thing.

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 detection 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 is fixed in a plane that is horizontal and nearly horizontal with respect to the element fixing table 1, whereas the laser chip 3 must be fixed in a vertical plane. However, there was a serious problem in alignment accuracy.

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

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

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. Thereby, a photodiode for signal detection (not shown) and a photodiode for laser output detection (not shown) can be mounted on the main surface of the silicon substrate 8, and the alignment accuracy can be improved.

Problems to be Solved by the Invention When a V-shaped groove whose slope is formed by the (111) plane is formed in the (100) plane silicon substrate 8, the groove is inclined with respect to the reflection mirror surface 9 and the surface of the silicon substrate 8. Since θ is about 55 °, there is a problem that the central axis of the emitted light is inclined about 20 ° from the direction perpendicular to the main surface of the silicon substrate.

In addition, photodiodes for various applications have to be mounted on a silicon substrate, and there is a problem that the assembly process is complicated.

Means for Solving the Problems A semiconductor laser device according to the present invention has a (100) plane silicon substrate having an off-angle of 5 ° to 15 ° about the <110> direction as an axis, and a slope on both sides is (111). A V-shaped or trapezoidal groove formed by a plane or a quadrangular pyramid or a truncated pyramid-shaped recess surrounded by four (111) planes is formed, and the inclination of the (111) plane with respect to the silicon substrate surface is formed. A surface close to 45 ° is a reflection mirror surface for reflecting laser light, and the semiconductor laser is so arranged that a front end surface of the semiconductor laser chip is substantially parallel to an upper edge line of the concave portion on a surface opposite to the reflection mirror surface. A chip is fixed to the silicon substrate, and signal detection photodiodes are formed on the silicon substrate in both directions of extension of the upper edge of the reflection mirror surface, respectively. The arm is divided into a plurality of parts, the direction of division is only in a direction parallel to the upper edge of the reflection mirror surface, and on a silicon substrate in the reflection mirror surface or on the silicon substrate behind the semiconductor laser chip. A photodiode for detecting laser output light is formed, and further, at least one of a photodiode for signal detection, a laser driving circuit, an amplifier circuit, and an optical signal processing circuit is formed on the silicon substrate.

Operation According to this configuration, the main surface of the silicon substrate is a surface provided with an off angle of 5 to 15 ° from the (100) plane, and thus the V-shaped or quadrangular pyramid formed by the (111) plane is formed. Angle θ between the reflection mirror surface of the 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 photodiode for detecting a laser output light is provided in a silicon substrate for a heat sink on which a laser chip is mounted.
Since the laser drive circuit, the amplifier circuit, and the optical signal processing circuit are formed, it is possible to eliminate the angle correction at the time of assembly and the complexity of the assembly process.

Embodiment An embodiment of the semiconductor laser device of the present invention will be described with reference to the perspective view and the cross-sectional view shown in FIG.

This is because a V-shaped groove (hereinafter referred to as V-shaped groove) in which both slopes 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.
A groove 11) is formed. Of these inclined surfaces, a surface having a slope θ closer to 45 ° with respect to the surface of the silicon substrate 10 is defined as a reflection mirror surface 12, and a surface opposite to this surface is formed with respect to a groove top ridge line. The structure is such that the laser chip 13 is fixed to the surface of the silicon substrate 10 so that the front end face of the semiconductor laser chip 13 is parallel. The surface of the reflection mirror surface 12 is 3000 to 5000
金 gold thin film 14 is formed, the mirror reflectivity is 90%
That's all. Further, 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, travels in the vertical or near vertical direction, and is extracted as output light.

In the embodiment, the V-groove has been described, but the apex of the V-groove may be flattened to form a trapezoidal groove.

In addition, although a (100) plane having an off angle of 10 ° was used as the surface of the silicon substrate, 5 to 15
A (100) plane having an off angle of ゜ may be used.
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.

Next, another embodiment of the semiconductor laser device of the present invention will be described with reference to the perspective view shown in FIG.

This provides the off-angle described in FIG.
A quadrangular pyramid-shaped concave portion 16 surrounded by four (111) planes is formed on the (0) plane silicon substrate 10, and the inclination of the four (111) planes with respect to the silicon substrate surface is set at 45 °. The nearest surface is a reflecting mirror surface 17 for reflecting the laser light, and the upper edge 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 face of the laser chip 13 is parallel to the laser chip 13. The structures of the reflection mirror surface 17 and the laser chip 13 are as described with reference to FIG.

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

In the embodiment, the concave portion having the shape of a quadrangular pyramid is described.

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

This is because a V-groove shown in FIG. 1 or a four-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 having a 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 reflection mirror surface 21 for reflecting laser light. An n-type diffusion region 22 is formed on the side, a silicon oxide film 23 for insulation and a gold thin film 24 are laminated on the reflection mirror surface 21, and a laser chip is formed on the upper edge of the surface facing the reflection mirror surface 21. In this structure, the laser chip 13 is fixed to the silicon substrate 20 so that the front end faces of the laser chips 13 are parallel.

The gold thin film 24 has a thickness of 500 to 1000 ° and is a semi-transmissive film, and a part of the laser light is incident on the photodiode constituted by the p-type silicon substrate 20 and the n-type diffusion region 23.

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

The light incident on the photodiode is changed into a current signal in accordance with the light intensity, and the current signal is fed back to the laser chip drive circuit and used to keep the output of the laser light constant.

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

This is because a V-groove shown in FIG. 1 or a four-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 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, and the upper end of the surface facing this surface A structure in which the laser chip 13 is fixed to the silicon substrate 20 so that the front end face of the laser chip 13 is parallel to the ridge line, and an n-type diffusion region 26 is formed on the P-type silicon substrate 20 behind the laser chip 13 It is.

The photodiode formed by the p-type silicon substrate 20 and the 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 changed according to the light intensity. This current signal is fed back to the laser chip drive circuit, and is used for monitoring to keep the intensity of the laser light emitted from the front end face of the laser chip 13 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 the gold thin film, travels in the vertical or nearly vertical direction, and is extracted as output light.

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

Next, another 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-type silicon substrate 20 having an off angle of about 10 ° with the <110> direction as a rotation axis.
A V-groove 11 having upper and lower slopes formed by the (111) plane is formed on the upper surface. Of these slopes, a surface closer to 45 ° with respect to the surface of the silicon substrate 20 is defined as a reflection mirror surface 12.
Laser chip against the top edge of the groove on the surface facing this surface
The laser chip 13 is fixed to the surface of the silicon substrate 20 so that the front end faces of the laser light 13 are parallel to each other, and a laser output light detection photodiode 29 is formed by forming an n-type diffusion region behind the laser chip 13, Further silicon substrate 20
The signal detection photodiode 30 is formed thereon.

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 reflection mirror surface 12 coated with the gold thin film and travels in the vertical or nearly vertical direction as shown in the optical path 15, It 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 and subjected to signal processing. On the other hand, the laser light emitted from the rear end face of the laser chip 13 is input to the laser output detection photodiode 29,
It 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 photodiode 29 for detecting the laser output light and the photodiode 30 for detecting the signal are formed on the same substrate, so that they can be miniaturized and 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. Can be formed on the same substrate.

Effect of the Invention According to the semiconductor laser device of the present invention, a (100) silicon substrate having an off angle of 5 to 15 ° with respect to the <110> direction is used, and
A groove or quadrangular pyramid-shaped recess is formed.
1) One of the surfaces has an inclination of about 45 ° with respect to the surface of the silicon substrate, and this surface can be used as a reflection mirror surface. As a result, the laser light emitted in the horizontal direction from the laser chip is reflected by the reflecting mirror surface and can be taken out substantially in the vertical direction, so that the alignment in the emission direction is simplified.

In addition, a photodiode for detecting laser output light, a silicon substrate for a heat sink on which a laser chip is mounted,
Since any one of the signal detection photodiode, laser drive circuit, amplifier circuit and optical signal processing circuit is formed, it can be integrated and the angle correction during assembly and the complexity of the assembly process can be eliminated. , Can reduce costs.

[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 a semiconductor laser device of the present invention having a quadrangular pyramid-shaped recess, and FIG. FIG. 4 is a cross-sectional view of the semiconductor laser device of the present invention in which a photodiode is formed on the reflection mirror surface side, FIG. 4 is a cross-sectional view of the semiconductor laser device of the present invention in which a photodiode is formed behind a laser chip, and FIG. FIG. 6 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 cross-sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a fixed base. FIG. 1 is a sectional view of a conventional semiconductor laser device in which a laser chip is mounted on a silicon substrate. 10: Silicon substrate, 11: V-shaped groove (V groove), 12, 17,
21 ... Reflective mirror surface, 13 ... Semiconductor laser chip, 14,2
4 ... Gold thin film, 15, 19, 25 ... Optical path, 16 ... Square pyramid concave part, 18 ... Top ridge line of square pyramidal concave part on the surface facing the reflection mirror surface, 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 ... Photodiode for detecting laser output light, 30.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Daisuke Ueda 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Denshi Kogyo Co., Ltd. Inside of Kogyo Co., Ltd. (72) Inventor Yuichi Shimizu 1006, Kazuma Kadoma, Kadoma, Osaka Prefecture Inside of Matsushita Electronics Corporation (56) References JP-A-61-42981 (JP, A) JP-A-62-23163 (JP) , A) Japanese Utility Model Showa 61-153360 (JP, U) Japanese Utility Model Showa 56-96665 (JP, U)

Claims (5)

(57) [Claims] 1. A V-shaped or trapezoidal shape in which slopes on both sides are formed by a (111) plane on a (100) plane silicon substrate having an off angle of 5 ° to 15 ° about a <110> direction as an axis. Or a quadrangular pyramid-shaped or truncated pyramid-shaped concave portion surrounded by four (111) surfaces, and the laser light is applied to a surface of the (111) surface having an inclination with respect to the silicon substrate surface of about 45 °. The semiconductor laser chip is fixed to the silicon substrate such that a front end surface of the semiconductor laser chip is substantially parallel to a reflection mirror surface to be reflected and an upper edge line of the concave portion on a surface opposite to the reflection mirror surface. A signal detection photodiode is formed on each of the silicon substrates in both directions of extension of the upper edge line of the reflection mirror surface, and the signal detection photodiode is formed by being divided into a plurality of parts. A semiconductor laser device wherein a direction is only a direction parallel to an upper edge line of the reflection mirror surface. 2. The semiconductor laser device according to claim 1, wherein a coating film for increasing the reflectance of the laser beam is provided on the reflection mirror surface. 3. The semiconductor laser device according to claim 1, wherein a photodiode for detecting a laser output is formed on a silicon substrate in a surface of the reflection mirror. 4. The semiconductor laser device according to claim 1, wherein a laser output detecting photodiode is formed behind the semiconductor laser chip on a silicon substrate to which the semiconductor laser chip is fixed. 5. A semiconductor laser driving circuit, a signal amplification circuit obtained from a laser output detection photodiode, and an optical signal processing circuit are formed on a silicon substrate to which a semiconductor laser chip is fixed. 2. The semiconductor laser device according to claim 1, wherein: