JPH08286016A - Optical element and semiconductor laser device - Google Patents

Abstract

PURPOSE: To reduce a stray noise by making the optical axis of an incident laser beam and inside surfaces of the recessed part of an optical element almost parallel. CONSTITUTION: In a semiconductor laser device provided with an optical element 11 having a recessed part whose inside surfaces become almost parallel with the optical axis or the part, a semiconductor laser chip 1 and a light receiving element 3, the semiconductor laser chip 1 and the optical element 11 are arranged so that the optical axis of the laser beam 13 emitted from the semiconductor laser chip 1 and the optical axis of the optical element 11 almost coincide. Then, since the parts made to be incident on the inside surfaces of the optical element having the recessed part among the laser beam from the semiconductor laser chip 1 are reflected to directions going out to the outside of the semiconductor laser device, the parts are prevented from being made incident on the light receiving element 3.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional optical element and semiconductor laser device will be described below. FIG. 8 is an exploded perspective view of a conventional optical element and semiconductor laser device. In FIG.
1 is a semiconductor laser chip, 2 is a heat sink, 3 is a light receiving element for signal detection, 4 is a light receiving element for monitoring, 5 is an optical element, 6 is a stem, 7 is an electrode terminal, 8 is an insulating member, 9 is a chip mounting portion. is there. Reference numeral 10 denotes a cap, which is usually made of a metal material, but is not necessarily limited to the metal material.

As shown in FIG. 8, the stem 6 has a chip mounting portion 9 and an electrode terminal 7 insulated by an insulating member 8.
And are mounted, and the monitor light receiving element 4 is mounted. The semiconductor laser chip 1 is mounted on the chip mounting portion 9 mounted on the stem 6 via the heat sink 2, and the light receiving element 3 for signal detection is further mounted. The semiconductor laser device is obtained by attaching the cap 10 having the optical element 5 attached thereto to the stem 6 and surrounding the above-mentioned constituent members.

In the semiconductor laser device having such a structure,
Since the laser light emitted from the semiconductor laser chip 1 spreads radially, a part of the laser light is diffusely reflected on the inner metal surface of the cap 10 and is incident on the light receiving element 4, which causes a problem that stray light noise is large.

In order to solve this problem, an optical element having a structure in which a material transparent to laser light, such as glass, is used to provide a concave portion for making the optical element also function as a cap, and the optical element A semiconductor laser device equipped with the same has been developed. An example of the structure is shown in the sectional view of FIG.

As shown in FIG. 9, this semiconductor laser device has a structure in which an optical element is integrated with a cap. That is, the light receiving element 4 for monitoring laser light is mounted on the stem 6, the semiconductor laser chip 1 is mounted on the chip mounting portion 9 attached to the stem 6 via the heat sink 2, and the light receiving element for signal detection. 3 has been implemented. Further, an optical element 11 having a recess is attached to the stem 6.

[0007]

However, in the above-mentioned conventional structure, the optical element 11 having the concave portion is usually formed with a taper on the inner surface of the concave portion so that the mold can be easily removed after molding. To do. Further, in order to prevent reflection, a non-reflection coating film is formed on the laser beam passage surface of the optical element 11, but at this time, the film thickness of the non-reflection coating film becomes uneven on the inner surface of the recess. A part of the laser beam emitted from the semiconductor laser chip 1 and radially spread reaches the inner side surface of the concave portion of the optical element 11 and has a lower reflectance than the reflection by the metal. And is incident on the light receiving element 3. For this reason, there is a problem that the stray light noise cannot be sufficiently reduced.

The present invention solves these conventional problems,
An object of the present invention is to provide a semiconductor laser device with reduced stray light noise.

[0009]

In order to achieve this object, the optical element of the present invention has a recess, and the inner surface of the recess is substantially parallel to the optical axis. Further, the semiconductor laser device of the present invention is provided with a structure in which the inner surface of the optical element having the concave portion and the optical axis when the laser light emitted from the semiconductor laser chip enters the optical element are substantially parallel to each other.

[0010]

With this structure, the laser light emitted from the semiconductor laser chip is reflected in the direction toward the outside of the semiconductor laser device on the inner surface of the recess of the optical element, so that the light is incident on the light receiving element and becomes stray light noise. Can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical element and a semiconductor laser device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of this embodiment. In FIG. 1, 1 is a semiconductor laser chip, 12 is a silicon substrate for heat sink, 3 is a light receiving element for signal detection, 4 is a light receiving element for monitoring, 11 is an optical element having a recess, 6 is a stem,
9 is a chip mounting part.

As shown in FIG. 1, in the present embodiment, the optical element 11 having the concave portion has its optical axis substantially aligned with the optical axis of the incident laser light 13, and further the laser light 1
3 has a recess whose inner surface is substantially parallel to the optical axis. The optical element 11 is attached to the stem 6, and the optical axis of the laser beam 13 incident from the semiconductor laser chip 1 is substantially parallel to the inner surface of the optical element 11 having the recess in the space surrounded by the recess and the stem 6. The semiconductor laser chip 1 is mounted and arranged on the chip mounting portion 9 via the silicon substrate 12 for heat sink so that Further, the signal detecting light receiving element 3 is attached to the chip mounting portion 9, and the laser light monitoring light receiving element 4 is attached to the stem 6 to form a semiconductor laser device.

In the optical element and the semiconductor laser device configured as described above, the laser light emitted from the semiconductor laser chip 1 spreads radially, and a part of the laser light is formed on the inner surface of the concave portion of the optical element 11. Since the light is reflected toward the outside of the device, it is prevented from entering the signal detection light receiving element 3 and the laser light monitoring light receiving element 4, and stray light noise can be reduced.

Next, an embodiment in which a holographic grating and a diffraction grating are formed on an optical element having a recess will be described. FIG. 2 is a cross-sectional view of an optical element having a holographic grating and a diffraction grating formed on the optical element having a recess, and a semiconductor laser device.

In the optical element and the semiconductor laser device shown in FIG. 2, the holographic grating 14 and the diffraction grating 15 are formed in the optical element 11 having the concave portion. It should be noted that either one of the holographic grating 14 and the diffraction grating 15 may be formed in the optical element 11. Further, a plurality of holographic gratings 14 and a plurality of diffraction gratings 15 may be formed. With such a configuration, functions such as beam splitting and light focusing can be realized, and the functions can be easily controlled by the patterns of the holographic grating 14 and the diffraction grating 15.

Next, an embodiment in which the light receiving element is multi-divided will be described. FIG. 3 is a sectional view of a semiconductor laser device in which the light receiving region of the signal detecting light receiving element is divided into a plurality of regions.

In the embodiment shown in FIG. 3, the light receiving region 16 of the signal detecting light receiving element 3 is divided into two or more. With such a configuration, it is possible to detect the size of the spot of the incident laser light, its shape, and the like. In addition, the light receiving element 3 for signal detection and the light receiving element 4 for monitoring laser light
It suffices that at least one of them is mounted as needed, and a plurality of each may be mounted. In the mounted light receiving elements, the light receiving areas of all the light receiving elements 4 may be multi-divided, or a part of the light receiving areas of the light receiving elements 4 may be multi-divided. Further, either one or both of the holographic grating and the diffraction grating may be formed in the optical element 11 having the concave portion, or both of them may be formed, or a plurality of each may be formed. With this configuration, the beam split,
Functions such as light collection can be realized, and the functions can be easily controlled by the pattern of the holographic grating and the diffraction grating.

Next, an embodiment in which the semiconductor laser chip is a surface emitting laser will be described. FIG. 4 is a sectional view of this embodiment.

In the semiconductor laser device shown in FIG. 4, the light receiving element 4 for monitoring is formed on the silicon substrate 12 for heat sink, and the surface emitting semiconductor laser chip 17 is mounted on the stem 6 via the silicon substrate 12 for heat sink. Has been done. With such a configuration, the semiconductor laser chip 17, the laser light monitor light-receiving element 4, and the signal detection light-receiving element 3 can be arranged two-dimensionally, which facilitates assembly. In the present embodiment, the monitor light receiving element 4 and the signal detecting light receiving element 3 are formed on the heat sink silicon substrate 12, but a plurality of chips may be mounted. As for the signal detection light-receiving element 3 and the monitor light-receiving element 4, at least one of them may be mounted as necessary.
In the mounted light receiving element 3, the light receiving areas of all the elements may be divided, or the light receiving areas of some of the elements may be divided. With such a configuration, it is possible to detect the size of the spot of the incident laser light, its shape, and the like. Furthermore, only one of the holographic grating and the diffraction grating may be formed in the optical element 11, or both of them may be formed. Further, a plurality of each may be formed. With such a configuration, functions such as beam splitting and focusing can be realized, and the functions can be easily controlled by the pattern of the holographic grating and the diffraction grating.

Next, an embodiment having a reflecting mirror for reflecting the laser beam emitted from the semiconductor laser chip will be described. FIG. 5 is a sectional view of this embodiment.

In the semiconductor laser device shown in FIG. 5, a silicon substrate 12 for heat sink is provided with a light receiving element 4 for monitoring laser light, a light receiving element 3 for signal detection, and a reflecting mirror 18, and the semiconductor laser chip 1 is for a heat sink. It is mounted on the stem 6 via the silicon substrate 12.

In this embodiment, the laser light 13 emitted from the semiconductor laser chip 1 is reflected by the reflecting mirror 18 and enters the optical element 11 having a recess. By making the inner surface of the recess of the optical element 11 having the recess substantially parallel to the optical axis of the laser light 13 reflected by the reflecting mirror 18, the emitted laser light 13 is reflected on the inner surface of the recess of the optical element 11. It is possible to prevent the light from being incident on the light receiving element 3 for signal detection.

With such a configuration, when the numerical aperture of the reflecting mirror 18 for the laser light from the semiconductor laser chip 1 is not sufficiently large, the laser light having a relatively high light intensity is directly applied to the inner surface of the recess of the optical element 11. Since it is incident, it is very effective in reducing stray light noise that the reflected light can be prevented from entering the light receiving element 4. Further, the semiconductor laser chip 1, the light receiving element 4 for monitoring, and the light receiving element 3 for signal detection can be arranged two-dimensionally, which facilitates assembly. In this embodiment, the light receiving element 4 for monitoring the laser light, the light receiving element 3 for signal detection, and the reflecting mirror 18 are formed on the silicon substrate for the heat sink, but a plurality of chips may be mounted. At least one of the signal detection light-receiving element 3 and the laser light monitoring light-receiving element 4 may be mounted as needed, and a plurality of each may be mounted. In the mounted light receiving element 3, the light receiving areas of all the elements may be divided, or the light receiving areas of some of the elements may be divided.
With this configuration, it is possible to detect the spot size of the incident laser light, its shape, and the like. Further, only one of the holographic grating and the diffraction grating may be formed in the optical element 11, or both of them may be formed together, and further, a plurality of each may be formed. . With such a configuration, functions such as beam splitting and focusing can be realized, and the functions can be easily controlled by the pattern of the holographic grating and the diffraction grating.

Next, an embodiment using a lead frame provided with a frame body made of an insulating material on the periphery will be described. Figure 6
6A is a top view thereof, and FIG. 6B is a sectional view thereof.

In the embodiment shown in FIGS. 6 (a) and 6 (b), the light receiving element 4 for monitoring laser light and the light receiving element 3 for signal detection are formed on the main surface of the silicon substrate 12 for heat sink, and the light receiving element 3 for signal detection is formed in the periphery. The surface emitting semiconductor laser chip 1 is mounted on the chip mounting portion of the lead frame 20 provided with the frame body 19 via the silicon substrate 12 for heat sink. With such a structure, a semiconductor laser device can be manufactured at a lower cost than a structure using a stem, and a large number of output terminals can be easily arranged. In addition, the semiconductor laser chip 1, the monitor light receiving element 4, the signal detecting light receiving element 3
Since it can be arranged two-dimensionally, it is easy to assemble. In the present embodiment, the laser light monitoring light receiving element 4 and the signal detecting light receiving element 3 are formed on the heat sink silicon substrate, but a plurality of chips may be mounted.
At least one of the signal detection light-receiving element 3 and the laser light monitoring light-receiving element 4 may be mounted as needed, and a plurality of each may be mounted. Further, in the mounted light receiving elements, the light receiving areas of all the light receiving elements may be multi-divided or some of the light receiving areas may be multi-divided. With this configuration, the size, shape, etc. of the spot of the incident laser light can be detected. Further, only one of the holographic grating and the diffraction grating may be formed on the optical element having the recess, or both of them may be formed, or a plurality of each may be formed. With such a configuration, functions such as beam splitting and focusing can be realized, and the functions can be easily controlled by the pattern of the holographic grating and the diffraction grating. Further, even if the reflecting mirror 18 and the semiconductor laser chip 1 are provided instead of the surface-emitting type semiconductor laser chip 1, the semiconductor laser chip 1 and the light receiving element 3 can be arranged two-dimensionally and the assembling can be easily performed.

The lead frame 20 in the embodiment of FIG.
By using a resin material as the insulating material of the frame body provided around the lead frame 20, the lead frame 20 provided with the frame body around the lead frame 20 can be manufactured at low cost. Thereby, the semiconductor laser device can be manufactured at low cost.

In the embodiments shown in FIGS. 1 to 6, the optical element having the recess may be made of a resin material which is transparent to the laser light emitted from the semiconductor laser chip.
By using a resin for the optical element having the concave portion, the optical element can be manufactured at low cost. Thereby, the semiconductor laser device can be manufactured at low cost.

[0029]

The present invention provides a semiconductor laser device provided with a semiconductor laser chip, a light receiving element, and an optical element having a recess and made of a material transparent to the laser light emitted from the semiconductor laser light. By configuring the optical axis of the laser beam when the laser beam emitted from the chip enters the optical element having the concave portion and the inner side surface of the concave portion of the optical element to be substantially parallel, it is excellent in reducing stray light noise. An optical element and a semiconductor laser device are provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical element and a semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a sectional view of an optical element and a semiconductor laser device according to another embodiment of the present invention.

FIG. 3 is a sectional view of an optical element and a semiconductor laser device according to still another embodiment of the present invention.

FIG. 4 is a sectional view of an optical element and a semiconductor laser device according to still another embodiment of the present invention.

FIG. 5 is a sectional view of an optical element and a semiconductor laser device according to still another embodiment of the present invention.

FIG. 6A is a top view of a semiconductor laser device of still another embodiment of the present invention, and FIG. 6B is a sectional view thereof.

7A is a top view of a semiconductor laser device of still another embodiment of the present invention, and FIG. 7B is a sectional view thereof.

FIG. 8 is an exploded perspective view of a conventional optical element and a semiconductor laser device.

FIG. 9 is a sectional view of an optical element and a semiconductor laser device using resin.

[Explanation of symbols]

 1 semiconductor laser chip 2 heat sink 3 light receiving element for signal detection 4 light receiving element for monitoring 5 optical element 6 stem 7 electrode terminal 8 insulating member 9 chip mounting part 10 cap 11 optical element 12 heat sink silicon substrate 13 laser light 14 holographic grating 15 Diffraction grating 16 Light receiving area 17 Surface emitting semiconductor laser chip 18 Reflector 19 Frame 20 Lead frame

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yoshikawa 1-1 Sachimachi, Takatsuki City, Osaka Prefecture Matsushita Electronics Industrial Co., Ltd.

Claims (11)

[Claims] 1. An optical element having a recess, wherein at least one of inner surfaces of the recess is substantially parallel to an optical axis. 2. The optical element according to claim 1, comprising one or more holographic gratings or one or more diffraction gratings or the holographic gratings and the diffraction gratings. 3. The optical element according to claim 1, which is made of a resin material. 4. A semiconductor laser chip, a light receiving element, and an optical element having a concave portion and made of an optical material transparent to a laser beam emitted from the semiconductor laser chip. A semiconductor laser device in which, when the emitted laser light is incident on the optical element, the optical axis of the laser light and at least one of the inner surfaces of the recess are substantially parallel to each other. 5. A semiconductor laser device comprising an optical element according to claim 4, comprising one or more holographic gratings, one or more diffraction gratings, or the holographic gratings and the diffraction gratings. 6. One or more light receiving elements are mounted,
The semiconductor laser device according to claim 4, wherein a part or all of the light receiving region is divided into a plurality of parts. 7. The semiconductor laser device according to claim 4, wherein the semiconductor laser chip is a surface emitting laser. 8. The semiconductor laser device according to claim 4, further comprising a reflecting mirror that reflects the laser light emitted from the semiconductor laser chip. 9. The semiconductor laser device according to claim 4, wherein the semiconductor laser and the light receiving element are arranged on a lead frame provided with a frame body on the periphery thereof, and the optical element is arranged on the frame body. 10. The semiconductor laser device according to claim 9, wherein the frame body is made of an insulating material. 11. The semiconductor laser device according to claim 4, wherein the optical element has a concave portion, and an optical element made of a resin transparent to light emitted from the semiconductor laser chip is mounted.