JPH05315700A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To improve an assembling accuracy by emitting light from a semiconductor laser toward a normal of a photodetector substrate and disposing the laser and the photodetector on the same flat surface. CONSTITUTION:A V-shaped groove 11 having oblique surfaces in a (111) plane is formed on a silicon substrate 10 in (511) plane having an off-angle of 1-11 deg. with a direction <110> as an axis, the oblique surface close to 45 deg. is used as a reflecting mirror surface 12, and a main surface 33 of the substrate 10 of the oblique surface side opposed to the surface 12 is formed lower than the other main surface 32, and further so disposed that the front end face of a semiconductor laser chip 13 becomes substantially parallel to a ridge of an end of the groove of the oblique surface opposed to the surface 12.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional semiconductor laser device will be described with reference to the 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 the light emitting surface of the laser chip 3 and the heat sink 2 are fixed. And the upper surface of the element fixing base 1 are aligned, 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 and is input to the signal detection photodiode 5 as reflected light 7 to be signal-processed. 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 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 laser light.

In this conventional configuration, the signal detecting photodiode 5 and the laser output light detecting photodiode 4 are fixed to the element fixing base 1 in a horizontal plane and a plane close to the horizontal plane, whereas the laser chip 3 is fixed. Since it has to be fixed in a vertical plane, the assembly work efficiency is poor and there is a big 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.

According to this structure, a V-shaped groove is formed on the (100) plane silicon substrate 8 with slopes on both sides formed by the (111) plane, and one surface of the slopes of the groove emits laser light. Is set as a reflection mirror surface 9 for reflecting light, and the main surface of the silicon substrate 8 on both sides facing the reflection mirror surface 9 is made lower than the other main surface, and the ridgeline at which 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 laser chip 3 from which the laser light is emitted is parallel.

According to this structure, the emitted light emitted from the laser chip 3 in the horizontal direction can be reflected by the reflecting mirror surface 9 and taken out substantially upward. As a result, a signal detection photodiode (not shown) and a laser output detection photodiode (not shown) can be formed on the main surface of the silicon substrate 8 and can be accurately formed by photolithography. ..

[0009]

In such a conventional configuration, for example, in the configuration of FIG. 7, the signal detection photodiode 5 and the laser output light detection photodiode 4 are arranged horizontally with respect to the element fixing base 1. The laser chip 3 must be fixed in a vertical plane, whereas the laser chip 3 must be fixed in a vertical plane, which complicates the assembling process, lowers the efficiency of the assembling work, and causes poor alignment accuracy. was there.

In the configuration shown in FIG. 8, (10
When a V-shaped groove having an inclined surface formed by the (111) surface is formed in the (0) plane silicon substrate 8, the inclination θ of the groove with respect to the reflection mirror surface 9 and the surface of the silicon substrate 8 is about 54 °. However, there is a problem that the central axis of the emitted light is tilted by about 18 ° with respect to the vertical direction of the main surface of the silicon substrate.

An object of the present invention is to solve the above problems, and an object thereof is to provide a semiconductor laser device in which the alignment of the emission direction of the laser beam is simple and the angle correction during the assembly and the assembly process are easy.

[0012]

In order to achieve the above object, the semiconductor laser device of the present invention comprises a (511) plane silicon substrate having an off-angle of 1 to 11 ° about the <110> direction as an axis. The slope is (111) and the cross-sectional shape is V
Of the (111) plane, which has an inclination close to 45 ° with respect to the surface of the silicon substrate, is used as a reflection mirror surface for reflecting laser light. The main surface is made lower than the other main surface, and the semiconductor laser chip is fixed to the silicon substrate so that the front end surface of the semiconductor laser chip is parallel to the upper edge of the surface facing the reflection mirror surface. The adopted configuration is adopted. Also, a configuration in which a photodiode for laser output light detection is formed on the silicon substrate on the side of the reflection mirror surface or on the silicon substrate behind the semiconductor laser chip, or a photodiode for signal detection on the silicon substrate, laser drive A configuration in which at least one of a circuit, an amplifier circuit, and an optical signal processing circuit is formed is adopted.

[0013]

According to this structure, the main surface of the silicon substrate is (5
Since the surface has an off angle of 1 to 11 ° with respect to the (11) surface, the angle θ between the reflection mirror surface of the V-shaped groove formed by the (111) surface and the main surface of the silicon substrate is 40.
The angle can be set in the range of ° ≦ θ ≦ 50 °, and the central axis of the laser light emitted from the semiconductor laser chip and reflected by the reflection mirror surface can be made substantially vertical to the main surface of the silicon substrate. it can.

A signal detection photodiode, a laser output light detection photodiode, a laser drive circuit, an amplifier circuit and an optical signal processing circuit are formed in a silicon substrate for a heat sink on which a semiconductor laser chip is mounted. Therefore, it is possible to reduce the number of parts as compared with a configuration in which they are individually arranged, and it is possible to reduce the cost because the angle correction during assembly and the complexity of the assembly process can be eliminated.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor laser device according to a first embodiment of the present invention will be described with reference to the perspective views shown in FIGS. 1 (a) and 1 (b) and the sectional view taken along the line AA.

This is a V-shaped groove formed by (111) planes on both sides on a (511) plane silicon substrate 10 having an off angle of about 6 ° with the <110> direction as a rotation axis. (Hereinafter, referred to as V groove) 11 is formed, and one of these slopes whose inclination θ with respect to the surface of the silicon substrate 10 is close to 45 ° is defined as a reflection mirror surface 12, and the surface of the silicon substrate opposite to this surface is formed. The main surface 33 to the other main surface 32
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 to the groove upper edge line of the surface facing the reflection mirror surface 12. is there. Such (1
11) The V-shaped groove 11 having the inclined surface can be easily realized by forming an oxide film etching mask on the silicon substrate 10 and etching with an anisotropic etching solution such as an aqueous potassium hydroxide solution or ethylenediamine. The surface of the reflection mirror surface 12 is 3000 to 5000 Å
The gold thin film 14 is formed, and the reflectance of the mirror is 90.
% Or more. Further, the leather chip 13 is fixed with a solder material so that the light emitting portion is on the lower side.

With this structure, the laser light emitted from the laser chip 13 in the horizontal direction is reflected by the reflection mirror as shown in the optical path 15, travels in the vertical direction or in the direction close to the vertical direction, and is taken out as output light.

Although the (511) plane having an off angle of about 6 ° was used as the surface of the silicon substrate, it has an off angle of 1 to 11 ° in actual use (511).
It may be a surface one. At this time, the inclination θ of the reflection mirror surface 12 with respect to the surface of the silicon substrate 10 is 40 ° ≦ θ ≦ 50 °.
Can be controlled within the range of, and a reflection mirror close to 45 ° can be obtained, and the same effect can be obtained. Further, a substrate equivalent to the silicon substrate 10 has an off-angle of 4 to 14 ° about the <110> direction as an axis (10
0) Similar effects can be obtained by setting an appropriate off angle from a silicon substrate or another crystal plane and adopting an equivalent substrate. The same applies to other embodiments described later.

Further, as shown in FIG. 1, the semiconductor laser chip 13 may be fixed with the light emitting surface side as the upper surface, without fixing the light emitting surface side (crystal growth surface side) as the adhesive surface. Since the manufacturing variation of the chip thickness is as large as ± 20 μm, the positional variation of the light emitting point becomes large. Therefore, when the semiconductor laser chip 13 is fixed with the light emitting surface as the adhesive surface, the distance from the silicon substrate 10 to the light emitting point has less variation and can be suppressed to about ± 2 μm. The effect of increasing the accuracy is obtained. The same can be said for other embodiments described later.

Next, a semiconductor laser device according to a second embodiment of the present invention will be described with reference to the perspective views and sectional views shown in FIGS. 2 (a) and 2 (b).

This is because the area of the main surface 33 which is lower than the main surface 32 of the (100) surface of the silicon substrate 10 provided with the off angle described with reference to FIG. 1 is an end surface of the silicon substrate 10. The structure is not limited to the above, but at least the region where the semiconductor laser chip 13 can be accommodated is formed. The structures of the reflection mirror surface 12 and the semiconductor laser chip 13 are as shown in FIG.

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

This is because the V groove shown in FIG. 1 is formed on the (511) plane P-type silicon substrate 20 having an off-angle of about 6 ° with the <110> direction as the rotation axis. The surface of the groove whose inclination is closer to 45 ° with respect to the surface of the silicon substrate 20 is the reflection mirror surface 21 for reflecting the laser beam, and the main surface 33 of the silicon substrate 20 on the side facing this surface.
Is lower than the other main surface 32, an n-type diffusion region 22 is formed on the P-type silicon substrate 20 side of the reflection mirror surface 21, and the insulating silicon oxide film 2 is formed on the reflection mirror surface 21.
3 and a gold thin film 24 are laminated, and the semiconductor laser chip 13 is fixed to the silicon substrate 20 so that the front end face of the semiconductor laser chip 13 is parallel to the upper edge line of the surface facing the reflection mirror surface 21. is there.

The gold thin film 24 has a thickness of 500 to 100.
In this structure, a semi-transmissive film is used as 0Å, and a part of the laser light is incident on the photodiode composed of the P-type silicon substrate 20 and the n-type diffusion region 22.

With this structure, the semiconductor laser chip 13
Part of the laser light emitted horizontally from the gold thin film 2
The light passes through the semi-transmissive film formed in 4 and is incident on the photodiode, and the rest is reflected by the semi-transmissive film and 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 changed into a current signal according to the light intensity, and this current signal is fed back to the laser chip drive circuit to be used to make the output of the laser light constant. It The same effect can be obtained even if the conductivity types of the silicon substrate 20 and the diffusion region 22 are reversed.

Next, a semiconductor laser device according to a fourth embodiment of the present invention will be described with reference to the sectional views shown in FIGS.

This is because the V groove shown in FIG. 1 is formed on the (100) plane P-type silicon substrate 20 having an off angle of about 6 ° about the <110> direction as a rotation axis. The surface of the groove whose inclination with respect to the surface of the silicon substrate 20 is 45 ° is defined as the reflection mirror surface 21 for reflecting the laser beam, and the main surface 33 of the silicon substrate on the side facing this surface is set to the other main surface 32. The semiconductor laser chip 13 is fixed to the silicon substrate 20 so that the front end surface of the semiconductor laser chip 13 is parallel to the upper edge of the surface facing the reflection mirror surface. This is a structure in which the n-type diffusion region 26 is formed over the main surface 33 of the silicon substrate 20 or a step formed by the main surface 32 and the main surface 33 as shown in FIG.

P-type silicon substrate 20 and n-type diffusion region 26
The photodiode formed in 1 receives the laser light emitted from the rear end surface of the semiconductor laser chip 13 and generates a current signal that changes according to the light intensity. This current signal is fed back to the laser chip drive circuit and used as a monitor for making the intensity of the laser light emitted from the front end face of the semiconductor laser chip 13 constant. This effect is the same even if the conductivity types of the silicon substrate 20 and the diffusion region 26 are reversed.

The laser light emitted from the front end face of the semiconductor laser chip 13 in the horizontal direction is reflected by the reflection mirror surface 21 coated with the gold thin film and travels in the vertical or nearly vertical direction to be extracted as output light. Be done.

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

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

In this structure, a V-shape is formed on the (511) plane of the P-type silicon substrate 20 having an off-angle of about 6 ° about the <110> direction as a rotation axis, and the slopes on both sides are formed by the (111) plane. The groove 11 is formed, and one of these slopes whose inclination with respect to the surface of the silicon substrate 20 is closer to 45 ° is used as the reflection mirror surface 12, and the main surface 33 of the silicon substrate 20 on the side facing this surface is the other surface. The semiconductor laser chip 13 is fixed to the surface of the silicon substrate 20 so that the front end face of the semiconductor laser chip 13 is parallel to the groove upper end ridge line of the surface which is lower than the main surface 32 and faces the reflection mirror surface 12, A laser output light detection photodiode 29 is formed by forming an n-type diffusion region behind the semiconductor laser chip 13, and a signal detection photodiode is further formed on the silicon substrate 20. The cord 30 is formed.

With this configuration, the semiconductor laser chip 13
The laser light emitted in the horizontal direction from the front end face of is reflected by the reflection mirror surface 12 coated with the gold thin film and advances in the vertical direction or a direction close to the vertical direction as shown in the optical path 15, and is extracted as output light. The signal light 31 in which the output light is reflected by the object is input to the signal detection photodiode 30 and signal-processed. On the other hand, the semiconductor laser chip 13
The laser light emitted from the rear end face is input to the laser output light detection photodiode 29 and converted into a current signal according to the light intensity. This current signal is fed back to the laser chip drive circuit and 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 provided.
Since they are formed on the same substrate, they can be integrated in a small size.

Although the photodiodes for laser output light detection and signal detection are shown in the embodiments, the present invention is not limited to this, and an amplifier circuit for a signal obtained from the photodiode, a drive circuit for a semiconductor laser chip, and an optical circuit. The signal processing circuit and the like can be formed on the same substrate. Further, these effects are the same even when the conductivity types of the substrate and the diffusion region are reversed. The laser output light detecting photodiode may have the structure shown in FIG. 3 described above.

[0037]

As is apparent from the above-described embodiments, the semiconductor laser device of the present invention has 1-1 to 1 axis in the <110> direction.
A (511) plane silicon substrate having an off-angle of 1 ° is used to form a groove having a V-shaped cross section with a (111) plane as a slope, and one of the (111) planes is the surface of the silicon substrate. Is about 45 °, and since this surface is used as a reflection mirror surface, the laser light emitted from the semiconductor laser chip in the horizontal direction is reflected by the reflection mirror surface and can be extracted in a substantially vertical direction. A semiconductor laser device that can be easily aligned can be provided.

Further, one or more of a laser output light detecting photodiode, a signal detecting photodiode, a laser driving circuit, an amplifying circuit and an optical signal processing circuit are provided on a silicon substrate for a heat sink on which a semiconductor laser chip is mounted. Since it is formed, it can be integrated and the angle correction at the time of assembly and the complexity of the assembly process can be eliminated,
A low-cost semiconductor laser device can be provided.

[Brief description of drawings]

FIG. 1A is a perspective view of a semiconductor laser device according to a first embodiment of the present invention, and FIG. 1B is a sectional view of the semiconductor laser device of FIG.

2A is a perspective view of a semiconductor laser device according to a second embodiment of the present invention, and FIG. 2B is a sectional view of the semiconductor laser device of FIG.

FIG. 3 is a sectional view of a semiconductor laser device according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view of a semiconductor laser device according to a fourth embodiment of the present invention.

FIG. 6 is a perspective view of a semiconductor laser device according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view of a conventional semiconductor laser device.

FIG. 8 is a sectional view of another conventional semiconductor laser device.

[Explanation of symbols]

 10 Silicon substrate 11 V-shaped groove 12 Reflection mirror surface 13 Semiconductor laser chip 14 Gold thin film (coating film) 15 Optical path 32 Main surface of silicon substrate (other main surface) 33 Main surface of silicon substrate (lowered main surface)

Claims (6)

[Claims] 1. A (511) plane silicon substrate having an off-angle of 1 to 11 ° about the <110> direction and both side slopes formed on a predetermined portion of the silicon substrate are (111) planes. A groove having a V-shaped cross section and an inclination of the slope forming the groove with respect to the surface of the silicon substrate is 4
The principal surface of the silicon substrate on the side of the inclined surface facing the reflection mirror surface close to 5 ° is made lower than the other principal surface, and the groove top edge line of the inclined surface opposed to the reflection mirror surface is formed on the lowered principal surface. A semiconductor laser device having at least a semiconductor laser chip fixed such that its front end faces are substantially parallel to each other. 2. A semiconductor laser device according to claim 1, wherein at least a region for accommodating a semiconductor laser chip in the main surface of the silicon substrate on the side of the slope facing the reflecting mirror surface is lower than the other main surface. 3. The semiconductor laser device according to claim 1, wherein the reflecting mirror surface is provided with a coating film for increasing the reflectance of the laser light. 4. The semiconductor laser device according to claim 1, wherein a photodiode for detecting laser output light is formed on the surface of the silicon substrate on the reflection mirror surface side. 5. A semiconductor laser device according to claim 1, wherein a photodiode for detecting laser output light is formed on the surface of the silicon substrate behind the semiconductor laser chip. 6. A laser drive circuit, a signal detection photodiode, an amplifier circuit for a signal obtained from the photodiode, and an optical signal processing circuit are formed on a silicon substrate on which a semiconductor laser chip is fixed. Claims 1, 2, 3, 4 or 5 characterized in that
The described semiconductor laser device.