JP3040252B2 - Semiconductor laser device - Google Patents

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 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 with respect to the other main surface, and the lower main surface of the silicon substrate 8 and the slope of the V-shaped groove are formed. The laser chip 3 is fixed such that the front end face from which the laser light of the laser chip 3 is emitted is parallel to the intersecting 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.
And can be formed with high precision by photolithography.

[0009]

In such a conventional configuration, for example, in the case of the configuration shown in FIG. 6, the signal detection photodiode 5 and the laser output light detection photodiode 4 are horizontal with respect to the element fixing base 1. The laser chip 3 must be fixed in a vertical plane, while the laser chip 3 must be fixed in a vertical plane. Therefore, the assembling process is complicated, the assembling work efficiency is low, and the positioning accuracy is poor. was there.

In the configuration shown in FIG.
When a V-shaped groove having an inclined surface formed by the (111) plane 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 °. In addition, there is a problem that the central axis of the emitted light is inclined by about 18 ° from the direction perpendicular to the main surface of the silicon substrate.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser device in which the positioning of a laser beam emitting direction is easy, the angle is corrected at the time of assembly, and the assembly process is easy.

[0012]

In order to achieve the above object, a semiconductor laser device according to the present invention comprises a (511) plane silicon substrate having an off angle of 1 to 11 ° with respect to a <110> direction as an axis. The slope is (111) plane and the cross-sectional shape is V
A groove or a quadrangular pyramid-shaped recess is formed.
1) The inclination of the surface to the silicon substrate surface is 45
The surface close to ° is the reflection mirror surface that reflects the laser light,
A configuration is adopted in which the semiconductor laser chip is fixed to the silicon substrate such that the front end face of the semiconductor laser chip is parallel to the upper edge of the slope facing the surface. Also,
A configuration in which a laser output light detection photodiode is formed on a silicon substrate on the reflection mirror surface side or on a silicon substrate behind the semiconductor laser chip, a signal detection photodiode on the silicon substrate, a laser driving circuit,
A configuration in which one or more of the amplifier circuit and the optical signal processing circuit are formed is employed.

[0013]

According to this structure, the main surface of the silicon substrate is (5
11) Since the surface has an off angle of 1 to 11 ° from the surface, the reflection mirror surface of the V-shaped groove or the quadrangular pyramid-shaped recess formed by the (111) surface and the main surface of the silicon substrate Can be in the range of 40 ° ≦ θ ≦ 50 °, and the central axis of the laser beam emitted from the semiconductor laser chip and reflected by the reflecting mirror surface is substantially perpendicular to the main surface of the silicon substrate. Direction.

Further, a photodiode for detecting a laser output light, a photodiode for detecting a signal, a laser driving 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, the number of components can be reduced as compared with a configuration in which these components are individually arranged, and angle correction at the time of assembly and the complexity of the assembly process can be eliminated, so that cost reduction can be achieved.

[0015]

DETAILED 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 and cross-sectional views shown in FIGS.

This is because a V-shaped groove in which both inclined surfaces are formed by the (111) plane on the (511) plane silicon substrate 10 having an off angle of about 6 ° with the <110> direction as the rotation axis. (Hereinafter referred to as a V-groove) 11 is formed, and a surface having a slope θ closer to 45 ° with respect to the surface of the silicon substrate 10 among these slopes is defined as a reflection mirror surface 12. Semiconductor laser chip 1
The laser chip 13 is fixed to the surface of the silicon substrate 10 so that the front end faces of the laser chips 3 are parallel to each other.

The V-groove having such a (111) slope is formed by forming an oxide film etching mask on a silicon substrate.
This can be easily realized by etching with an anisotropic etching solution such as an aqueous solution of potassium hydroxide or ethylenediamine.

The surface of the reflecting mirror surface 12 has a thickness of 300
The gold thin film 14 of 0 to 5000 ° is formed, and the reflectance of the mirror is 90% or more. 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 and travels in the vertical or nearly vertical direction, and is extracted as output light. It is.

In this embodiment, the V-groove has been described.
The same effect can be obtained by making the apex of the V groove flat and trapezoidal groove.

Although the surface (511) having an off-angle of about 6 ° was used as the surface of the silicon substrate, it actually has an off-angle of 1 to 11 ° (511).
It may be a surface thing. At this time, the inclination θ of the reflection mirror surface 12 with respect to the surface of the silicon substrate 10 is set to 40 ° ≦ θ ≦ 50 °.
And a reflection mirror close to approximately 45 ° can be obtained, and the same effect can be obtained. Further, as a substrate equivalent to the silicon substrate 10, an off-angle of 4 to 14 ° with the <110> direction as an axis (10
0) A similar effect can be obtained by setting an appropriate off-angle from a silicon substrate or another crystal plane and using an equivalent substrate. The same can be said for the other embodiments described later.

Further, the semiconductor laser chip 13 may be fixed with the light emitting surface side as the upper surface instead of fixing the light emitting surface side (crystal growth surface side) as an adhesive surface as shown in FIG. Since the chip thickness has a large manufacturing variation of ± 20 μm, the position variation of the light emitting point becomes large. Therefore, when the semiconductor laser chip 13 is fixed with the light emitting surface side as the adhesive surface, the distance from the silicon substrate to the light emitting point has less variation and is kept to about ± 2 μm, so that the positioning of the light emitting point is more accurate. Is obtained. The same can be said for the 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 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 is formed, and a reflection mirror that reflects a laser beam on a surface of the four (111) surfaces that is closest to the surface of the silicon substrate 10 at an inclination of 45 ° is reflected. The laser chip 1 is defined as a surface 17 and a top edge line 18 of the quadrangular pyramid-shaped recess 16 on a surface facing the surface 17.
The laser chip 13 is fixed to the silicon substrate 10 so that the front end faces of the laser chips 3 are parallel to each other. 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 an optical path 19 and travels in a vertical or nearly vertical direction, and is output as light. Taken out.

Although the embodiment has been described using a quadrangular pyramid-shaped concave portion, the vertex of this concave portion may be flattened to have a truncated quadrangular pyramid shape.

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.

The V-groove shown in FIG. 1 or the V-groove shown in FIG. 2 is formed on a (511) plane P-type silicon substrate 20 having an off-angle of about 6 ° 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 reflection mirror surface 21 for reflecting laser light. 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 a reflection mirror surface 21, and a laser is applied to the upper edge of the surface facing the reflection mirror surface 21. Chip 13
Has a structure in which 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 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 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 changed 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. 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 view shown in FIG.

The V-groove shown in FIG. 1 or the V-groove shown in FIG. 2 is formed on the (511) plane P-type silicon substrate 20 having an off angle of about 6 ° 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 reflection mirror surface 21 for reflecting laser light, and a surface facing the surface is formed. 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
The photodiode formed by receives the laser light emitted from the rear end face of the semiconductor laser chip 13 and generates a current signal changed according to the light intensity. This current signal is fed back to the semiconductor laser chip drive circuit, and is used for monitoring to make the intensity of laser light emitted from the front end face of the semiconductor laser chip 13 constant. This effect is the same even when the conductivity types of the silicon substrate 20 and the diffusion region 26 are reversed.

The laser light emitted in the horizontal direction from the front end face of the semiconductor 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. It is.

Reference numeral 27 denotes an optical path of laser light emitted from the rear end face of the semiconductor laser chip 13, and reference numeral 28 denotes an optical path of 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, both slopes are formed by the (111) plane on the (511) plane P-type silicon substrate 20 having an off angle of about 6 ° with the <110> direction as the rotation axis. A groove 11 is formed, and a surface of the inclined surface, the inclination of which is closer to 45 ° with respect to the surface of the silicon substrate 20, is defined as a reflection mirror surface 12. The semiconductor laser chip 13 is fixed to the surface of the silicon substrate 20 so that the front end faces of the semiconductor laser chip are parallel to each other, and a laser output light detecting photodiode 29 is formed by forming an n-type diffusion region behind the semiconductor laser chip 13. In addition, a photodiode 30 for signal detection is formed on a silicon substrate 20.

With this configuration, the semiconductor laser chip 13
The laser light emitted in the horizontal direction from the front end face of the laser light is reflected by the reflecting mirror surface 12 coated with the gold thin film, travels in the vertical or nearly vertical direction as shown by the optical path 15, and 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 semiconductor laser chip 13
The laser light emitted from the rear end face 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 used to make the output of the laser light emitted from the front end face of the semiconductor 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. The amplifier circuit for the signal obtained from the photodiode, the driving circuit for the semiconductor laser chip and An optical signal processing circuit and the like can be formed over the same substrate. These effects are the same even when the conductivity types of the substrate and the diffusion region are reversed. Further, the photodiode for detecting laser output light may have a structure as shown in FIG. 3 described above.

[0042]

As is clear from the above embodiments, the semiconductor laser device of the present invention has a structure of 1 to 10 with the <110> direction as an axis.
Using a (511) plane silicon substrate having an off angle of 11 °, a groove having a slope of (111) plane and a V-shaped cross section or a 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 is used as a reflection mirror surface, so that the laser light emitted in the horizontal direction from the laser chip is reflected by the reflection mirror surface, It is possible to provide a semiconductor laser device that can be taken out in a substantially vertical direction and that can easily be aligned in the emission direction.

Further, on a silicon substrate for a heat sink on which a semiconductor laser chip is mounted, at least one of a photodiode for detecting laser output light, a photodiode for detecting a signal, a laser driving circuit, an amplifier circuit, and an optical signal processing circuit. Are formed, so that they can be integrated, can eliminate angle correction at the time of assembly and the complexity of the assembly process, and can provide a low-cost semiconductor laser device.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of a semiconductor laser device according to a second embodiment of the present invention.

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

FIG. 6 is a sectional view of a conventional semiconductor laser device.

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

[Explanation of symbols]

 DESCRIPTION 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-253983 (JP, A) JP-A 61-153360 (JP, U) JP-A 61-166863 (JP, U) JP-A 63-153 75063 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (6)

(57) [Claims] 1. An off- axis with respect to a (511) plane silicon substrate.
The main surface is formed with an angle and (11
1) having a silicon substrate having a slope formed of a surface,
The angle between the slope and the main surface is 40 degrees or more and 50 degrees or less
And the laser light is directed to the concave portion so as to be directed to the slope.
Along which a semiconductor laser device is mounted on the main surface
Laser device. 2. The method according to claim 2, wherein the surface of the concave portion is a side surface or a quadrangular pyramid.
2. The semiconductor laser device according to claim 1, including a side surface of the truncated pyramid. 3. A cut in a plane perpendicular to the main surface of the recess.
2. The semiconductor laser according to claim 1, wherein the cross-sectional shape is V-shaped.
apparatus. 4. A coating film is formed on the slope.
The semiconductor laser device according to claim 1. 5. A pn junction is provided along the slope.
2. A light receiving element for detecting a laser output is formed.
Semiconductor laser device. 6. A light receiving element is provided on said silicon substrate.
The light receiving element is formed in both extension directions of the upper edge line of the slope.
Claims and divided by a line parallel to the top edge line
2. The semiconductor laser device according to 1.