JPH02230783A - semiconductor laser equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device that emits multiple laser beams. [Prior Art] Consideration has begun to be given to the use of multi-beam semiconductor laser devices in optical application equipment such as optical disks. By assigning different functions to multiple laser beams, we aim to increase the functionality and speed of optical applications. Conventional multi-beam semiconductor laser devices are described, for example, in Proceedings of the International Symposium on Optical Memory; 1987, Japanese Journal of Applied Physics, Vol. 26 (1987), Sublument 2, 6-4.
Proc. Int. Symp. on Optical
Memory, 1987, Japanese Jo
urnal of Applied Physics,
Vol. 26 (1987) Supplement 2
6-4, Proceedings of the 35th Applied Physics Association Conference, Spring 1988, p. El98, lecture number 3 0 p.
- Z Q - A hybrid laser array as described in 31C is known. This laser device is characterized by a structure in which the electrode surfaces of a pair of semiconductor lasers face each other, and the beam spacing can be made close to several tens of μm without causing thermal interference. It is desirable to keep the beam spacing as close as possible in order to miniaturize the optical system for optical application functions. By the way, in the above-mentioned optical application equipment, each beam has a different function, so the optical output of each beam must be detected independently and each laser must be controlled individually. However, since the above device itself does not have a photodetection function, it is necessary to install a photodetection element (light receiving element) and an optical system to guide the beam outside the device, which causes the problem of increasing the size of the device. Ta. In order to miniaturize optical equipment, it is essential to provide a light receiving element inside the laser device. Regarding the method of arranging a light receiving element inside a laser device, a method for a conventional single beam semiconductor laser device is known.
For example, as described in JP-A-60-12786,
Light receiving element (chip size approx. 1cm) relative to the beam emission direction
The light-receiving surface (several 100 μm in diameter) of the corner) was arranged so that it was approximately vertical. This method is applied to the above-mentioned multi-beam semiconductor laser device, and FIG. 6 shows a diagram in which the light receiving elements are arranged in parallel. In FIG. 6, 101 and 102 are lasers, and 103 and 104 are submounts. 105 and 106 are mounts, 1o7 is a pedestal, and 108 and 109 are light receiving elements 110 and 111 are light receiving surfaces of the light receiving elements 108 and 109, respectively. As is clear from the figure, in this method, the beam distance between the lasers 101 and 102 is about 1 mm. Therefore, there is a problem that it is not possible to reduce the size of the laser device itself and the optical system of the optical application equipment. Furthermore, since the beam is emitted at a spread angle of several tens of degrees, there is a problem in that the beam of the laser 101 is incident on the light receiving surface 111 and the beam of the laser 102 is incident on the light receiving surface 110, resulting in large crosstalk. That is, even if the conventional method of arranging light receiving elements is applied to a multi-beam semiconductor laser device, each beam cannot be detected independently.

As a method of arranging the light receiving element inside the laser device, a new method as shown in FIG. 7 can be considered.

In FIG. 7, 120, 121 are lasers, 122, 1
23 is a submount, 124 and 125 are mounts, 12
6 is the pedestal. 127, 128 are light receiving elements, 129, 130
are the light-receiving surfaces of the light-receiving elements 127 and 128, respectively. Lasers 120, 121 and light receiving elements 127, 128 are mounted on common submounts 122, 123, respectively. According to this method, the beam spacing can be reduced to several tens of μm.
can be brought close to each other.

However, since the beam of the laser 120 is incident on the light receiving surface 130 and the beam receiving surface 129 of the laser 121, the problem of crosstalk still remains. Figure 8 is a graph with beam spacing on the horizontal axis and gross talk on the vertical axis. Crosstalk is expressed in dB as the amount of crosstalk light relative to the amount of signal light incident on the light receiving surface. The results in FIG. 7 are shown in the line b (the distances between the end faces of the lasers 120 and 121 and the centers of the light receiving surfaces 129 and 130 are respectively 5
00μm. Electrode surfaces of lasers 120 and 121 and light receiving surface 12
9,130 is 100 μm). As can be seen from this result, for example, when the beam spacing is 50 μm, the crosstalk is as high as −3.4 dB, which is a practical problem.

[Problem to be solved by the invention]

The conventional multi-beam semiconductor laser device described above does not take into account the photodetection function. Furthermore, even if conventional photodetection technology was applied to this device, multiple beams would be incident on the same photodetector, so crosstalk would be large and each beam could not be detected independently. SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-beam semiconductor laser device having a function of detecting each beam independently, and to further reduce the size of the device. [Means for Solving the Problems] In order to achieve the above object, the present invention makes two beams emitted from the above-mentioned pair of conventional lasers enter a pair of optical waveguides obliquely with respect to the optical axis. Two beams reflected by the light output end face of the processed optical waveguide are incident on a pair of light receiving elements, respectively. [Operation] The two beams emitted from the pair of lasers travel through separate optical paths and reach separate light-receiving elements, so they are detected independently. Since each beam is confined by an optical waveguide, no angular spread occurs and crosstalk between photodetectors is prevented. In addition, since the direction of the optical path is changed by the diagonally processed surface, it is possible to arrange the light-receiving elements so that their light-receiving surfaces face each other.
The laser device can be made smaller compared to when the photodetectors are arranged in parallel. [Examples] Examples of the present invention will be described below with reference to the drawings. FIG. 1 is an overall perspective view showing a first embodiment of the present invention, and FIG. 2 is a partially enlarged view of the first embodiment. First, we will discuss the overall configuration. In FIGS. 1 and 2, a pair of semiconductor laser chips 1 and 2 are arranged so that their electrode surfaces face each other. Furthermore, the lasers 1 and 2 are provided with submounts 3 and 3, respectively.
・Two mounts 5 facing each other across space via 4
,6 are loaded separately. Mounts 5 and 6 are fixed to pedestal ↓2, and pedestal 12 is welded to the plate. Holes 20 and 21 in plate 22 are for screwing. The cap 8 is welded to a plate 22, and two laser beams 1 and 2 are emitted from the window 7. Electrode pin 13 is for driving laser 1,
14 is for light detection of laser 1, 17 is for driving laser 2, 1
6 is for light detection of laser 2, and 15 is a ground pin. 1
8.19, the sealing glass mount 5 side (laser 1 side) and the mount 6 side (laser 2 side) for electrically insulating the plate 22 and pins 13 and 14 have almost the same structure and component configuration. (although the mount 6 side is in the shadows and cannot be seen), and they face each other in pairs. Figure 2 shows mount 5.
Only the sides are shown enlarged. The beam of the laser 1 is emitted upward and downward from the active layer 31.

The beam emitted downward enters the optical waveguide 9 from the surface 32, is reflected by the obliquely processed surface 33, and enters the light-receiving surface 35 of the light-receiving element 11. The optical waveguide 9 is fixed to the submount 10 by adhesive injection 34, and the optical waveguide 10 is fixed to the mount 5. Next, we will explain the details of each part. When the first embodiment is used, for example, in an optical disc device, the laser 1 has an oscillation wavelength of 78 cm.
0nm low noise reproduction laser, laser 2 has an oscillation wavelength of 83
Employs a 0nm high-power writing laser. The size of the laser chip is several hundred μm square and approximately 100 μm thick. Submount 3.4 is made of electrically insulating and highly thermally conductive SiC
It is made of ceramics (thickness: 200 μm), and A u / P t / Ti metallized patterns 36 and 37 for electrode wiring are formed on its surface. The upper electrode of the laser is connected to the pin 18 via a wire 38, a pattern 36, and a wire 39, and the lower electrode is grounded to the mount 5 via a pattern 37 and a wire 40. All wires used were Au wires. The optical waveguide 9 is made of a glass material with good light transmittance, such as quartz glass. The creation method is to first process a glass plate vertically and diagonally (32 sides each).
and 33) and cut it out to the desired size. The size of the optical waveguide 9 used in the first embodiment is a width of 2
00μm. The thickness was 100μ, the length was 1.35m, and the diagonal processing angle was 45°. Incidentally, in order to reduce the light reflected back from the surface 32 to the laser 1, a non-reflection coating was applied to the surface 32. The distance between laser 1 and surface 32 was set to 50 μm.
The submount 10 was created by cutting out a 200 μm thick Si wafer. The light receiving element 11 is a PIN type photodiode, and the size of the light receiving surface 35 is 300 μmφ. The upper electrode of the light receiving element is connected to the bottle 14 by a wire 41, and the lower electrode is grounded to the mount 5. The mounts 5 and 6 are made of Cu, which has good thermal conductivity. The surfaces of the mounts 5 and 6 are covered with the submounts 3 and 4 and the photodetector element 1.
A u to improve wettability when soldering 1st grade.
/Ni-plated. Mounts 5 and 6 are
After the positions of the light emitting points of lasers 1 and 2 are relatively aligned, they are fixed to the pedestal 12 by soldering. In order to reduce solder fatigue, the pedestal 12 is made of the same <Cu as the mounts 5 and 6, and its surface is plated. The reason why the pedestal 12 is stepped is that it has a stepped shape (see Figure 1). This is to facilitate the work of attaching wires such as 39 and 41.

According to the first embodiment, two beams emitted from a pair of semiconductor laser chips are guided by separate optical waveguides and detected by a pair of light receiving elements. In other words, the effect is that the two beams can be detected independently. The size of the entrance surface of the optical waveguide is small enough to suppress inter-beam crosstalk within an acceptable range, and large enough to obtain sufficient optical coupling efficiency with each beam. The desired value of optical coupling efficiency can be obtained by adjusting the position of the optical waveguide (submount) with respect to the laser chip. In addition, since the optical path is changed in direction by the diagonally machined surface, the light-receiving elements can be placed facing each other, making it possible to achieve compact integration. Furthermore, since it has a hybrid structure, you can choose any combination of laser chip and photodetector, and
This has the advantage that the relative positional relationship between optical waveguides can be easily changed as necessary. The effects of the first embodiment are shown in the graph of FIG. In Figure 8, the horizontal axis is the beam spacing and the vertical axis is the crosstalk. The results of this first example are shown on line a. From the figure, according to the first embodiment, even if the beam spacing is narrowed to 50 μm or less, crosstalk is still suppressed to -20 dB or less.
There is no practical problem at all, and each beam can be detected independently. When compared with the result of the technique shown in FIG. 7 (line b) described above, the effect of the first embodiment is clear. In the first embodiment described above, the submounts for the laser chip and the optical waveguide were different. In the second embodiment, a case in which a common submount is used will be described below. Figure 3 is a partially enlarged view of the second embodiment. The overall configuration is the same as that of the first embodiment shown in FIG. 1, so a description thereof will be omitted. 50 is a submount common to the laser 1, the optical waveguide 9, and the light receiving element 11. Made of SiC ceramics. A step is provided at the light receiving element 11. The surface is partially covered with A u / P t / Ti metallization (51
, 52, 53) have been applied. The upper electrode of the laser 1 is connected to the electrode pins via the wire 54, the pattern 51, and the wire 55, and the lower electrode is grounded to the mount 5 for the pattern 52 and the wine 56. The upper electrode of the light receiving element 11 is grounded to the electrode bin via a wire 58, and the lower electrode is grounded to the mount 5 via a pattern 53 and a wire 57. The optical waveguide 9 has a surface partially coated with Au/Ni
/ Ti metallization 59 is applied and fixed to the submount 50 with solder 6o. The pattern 52 serves both as electrode wiring and soldering. Since the laser 1 and 2 sides have a symmetrical structure, the 2
We omitted the explanation of the sides. According to the second embodiment,
The laser 1, the light receiving element 11, and the optical waveguide 9 are assembled on the submount 50 in advance, and the submount 50 is assembled later.
Just fix it to mount 5. Compared to the first embodiment, in which each element had to be assembled on the mount 5 one after another, work efficiency is improved. Furthermore, even if the polarity of the laser 1 or the light receiving element 11 is changed,
This can be achieved by slightly changing the metallization pattern on the submount 50 and the wire attachment (in the first embodiment, the polarity of the lower electrode of the light receiving element 11 was fixed to ground). In the first embodiment, the leading waveguide 9 is
However, in the second embodiment, the optical waveguide 9 is also fixed by soldering, which has good heat resistance characteristics and has the effect of improving reliability. FIG. 4 is a side view of a third embodiment of the present invention, and the overall configuration is similar to FIG. 1. Since the mount 5 and 6 sides are symmetrical, only the 5 side is shown. In the third embodiment, a lens 71 is formed on the incident surface of the optical waveguide 70 in order to increase the efficiency of optical coupling between the laser 1 and the optical waveguide 70. The beam emitted from the laser 1 is focused by a lens 71, reflected by a surface 72 (arrow in the figure), and enters a light receiving element. According to the fourth example, the laser beam can be detected independently with high sensitivity. FIG. 5 is a side view of a fourth embodiment of the present invention. The overall configuration is similar to Figure 1. The mount 5 and 6 sides are symmetrical, so only the 5 side is shown. In the fourth embodiment, in order to increase the incidence efficiency of the beam propagating through the optical waveguide 73 into the light receiving element 11, the surface 74 is curved to condense the reflected light onto the light receiving surface of the light receiving element 11 ( (arrow in figure). According to the fifth embodiment, there is an effect that the light reception efficiency of the laser beam is improved. The present invention has been explained above using the drawings. The requirements of the present invention are that two laser beams emitted from a pair of semiconductor laser chips are incident on a pair of optical waveguides, and two laser beams are reflected by the light output end face of the optical waveguides that is processed obliquely with respect to the optical axis. The reason is that two laser beams are detected by a pair of photodetectors. Therefore, the present invention is not limited by the characteristics and types of the laser chip, photodetector, and optical waveguide, nor by the materials, sizes, etc. of each component of the device. As the optical waveguide, a glass square material was used in the examples, but it is also possible to use a fiber or channel type optical waveguide.
It is also possible to adopt a configuration in which a laser chip, a light receiving element, and an optical waveguide are monolithically integrated and arranged so as to face each other. Furthermore, although a pair of laser chips is shown in the embodiment, the effects of the present invention are obvious even when there are multiple pairs of chips. Furthermore, by using the semiconductor laser device of the present invention, it was possible to independently control each laser chip in optical application equipment such as optical disk devices, laser beam printers, and optical measurement sensors, thereby achieving multifunctionality and high speed. [Effects of the Invention] According to the semiconductor laser device of the present invention, it is possible to independently detect a plurality of laser beams, so each laser can be independently controlled. This has the effect of easily increasing the functionality of optical application equipment using this device. Furthermore, since this device is small despite its added functions, optical application equipment itself can also be made smaller.

[Brief explanation of the drawing]

1 is an overall perspective view of the first embodiment of the present invention, FIG. 2 is a partially enlarged perspective view of the first embodiment, FIG. 3 is a partially enlarged perspective view of the second embodiment, and FIG. 4 is a partially enlarged perspective view of the second embodiment. Partial side view of 3rd embodiment, 5th
The figure is a partial side view of the fourth embodiment, both Figures 6 and 7 are diagrams showing conventional photodetection technology, and Figure 8 is a graph diagram showing the relationship between beam spacing and crosstalk. 1, 2... Laser, 3, 4... Submount, 5,
6... Mount, 9... Optical waveguide, 11... Light receiving element, 12... Pedestal, 32.33... Surface. 7.2 3,4 5.6? Racepubumau'/Tomafunt tip 4 liquid bath pedestal 70 Liquid guide 71 L-/x- Submount/03. 109. /27. /273 Shisaki Kueta

Claims (1)

[Claims] 1. In a semiconductor laser device in which the electrode surfaces of at least one pair of semiconductor laser chips are arranged to face each other, two laser beams emitted from the pair of semiconductor laser chips are connected to a pair of optical waveguides. What is claimed is: 1. A semiconductor laser device, characterized in that the semiconductor laser is detected by a pair of light-receiving elements after being incident on the light-emitting end face of the pair of optical waveguides processed obliquely with respect to the optical axis; 2. The semiconductor laser device according to claim 1, wherein the pair of semiconductor laser chips are separately mounted on two mounts facing each other across a space, and the pair of optical waveguides and the pair of light receiving elements are respectively mounted on two mounts facing each other with a space between them. A semiconductor laser device characterized in that it is mounted on the same mount as a corresponding semiconductor laser chip. 3. In the semiconductor laser device according to claim 1 or 2, the pair of semiconductor laser chips are of an edge-emitting type, and the pair of light-receiving elements are of a surface-emitting type, and the optical axes of the pair of semiconductor laser chips correspond to this. The semiconductor laser device is substantially parallel and coincident with the optical axes of the pair of optical waveguides, and substantially orthogonal to the optical axes of the pair of light receiving elements. 4. The semiconductor laser device according to claim 2 or 3, wherein the semiconductor laser chip, the optical waveguide, or the light receiving element is mounted on a mount via a submount made of an electrically insulating material, and a metallized pattern is formed on the surface of the submount. A semiconductor laser device characterized in that: 5. The semiconductor laser device according to any one of claims 2 to 4, wherein the optical waveguide is metallized on a part of a side surface other than a laser light incident surface and an exit surface. . 6. The semiconductor laser device according to claim 1, wherein a lens is formed on the laser incidence surface of the optical waveguide. 7. The semiconductor laser device according to claim 1, wherein the obliquely machined surface of the optical waveguide is curved. 8. independently detecting two laser beams from the pair of semiconductor laser chips using the semiconductor laser device according to claim 1;
An optical application device characterized in that the output of the laser beam is individually controlled.