JPH0429582Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention relates to a semiconductor laser device, and is useful as a light source for an optical disk device, for example.

(b) Prior art A three-beam type semiconductor is used as a light source for optical disk devices, in which individual beam generation sources that can independently emit erasing, reading, and writing laser beams are arranged in parallel at intervals of approximately 100 μm. A laser device has been proposed (Utility Model Application Publication No. 152474/1983).

Since semiconductor laser beam sources emit beams in two directions, one of the emitted beams is typically used to monitor the output intensity. Therefore, in the case of a three-beam type, as disclosed in Japanese Patent Laid-Open No. 58-102590, semiconductor light receiving sections for monitoring are arranged close to one side of each of the beam generation sources.

However, since the horizontal spread angle θ of the beam emitted from the semiconductor laser beam source is at least about 10°, accurate monitoring cannot be performed unless the arrangement interval between the beam source and the light receiving element is set to 500 μm or less. That is, as shown in FIG. 4, a semiconductor laser means LD having beam generation sources 1 to 3 arranged side by side with the distance between the optical axes 4 of each beam being 100 μm, and semiconductor light receiving parts 5 to 7 facing this are arranged. Furthermore, assuming that the horizontal spread angle θ of each beam is 10°, and the distance between each beam source and the light receiving part is 500 μm or more,
Each of the beams 1a to 3a overlaps in the light receiving sections 5 to 7, making it impossible to monitor each individual beam.

If the distance between each beam source and the light receiving section is made smaller, the overlap of the beams will be eliminated, but placing them close together in this way will cause problems in terms of assembly, such as making it difficult to align the optical axes between the beam generating source and the light receiving section. The problem arises.

In view of this point, as shown in FIG.
A configuration was proposed in which the semiconductor laser means LD and the monitor light receiving means PD were arranged (electronic material).
Vol.26, No.． 6, 1987, P107) That is, the waveguide member 8 is provided with a plurality of waveguide grooves 9 to 11 that direct the laser beams emitted in one direction from the semiconductor laser means LD in mutually discrete directions,
Therefore, the three beams 1a to 3a emitted from the semiconductor laser LD at intervals of 100 μm pass through the waveguide member 8, are spread out at appropriate intervals without overlapping, and enter the corresponding light receiving sections 5 to 7.

(c) Problems to be solved by the invention In the waveguide member 8, the waveguide groove 1 in the center of the waveguide member 8 is
0 coincides with the optical axis 4 of the beam generation source 2, and therefore the beam traveling in the waveguide groove 10 travels almost straight, with almost no beam attenuation within the waveguide groove. On the other hand, since the arrangement direction of the waveguide grooves 9 and 11 on both sides is inclined with respect to the optical axis 4 of the beam generation sources 1 and 3, the beam traveling inside these waveguide grooves is After repeated reflections, beam attenuation within the waveguide groove is observed.

As a result, even if each of the beam generation sources 1 to 3 emits a beam of the same intensity, each of the light receiving sections 5 to 7 cannot obtain an equal output, resulting in a decrease in monitoring accuracy.

The present invention therefore attempts to solve the problem of attenuation within each waveguide groove when using the above-mentioned waveguide member.

(d) Means for solving the problem The feature of the semiconductor laser device of the present invention is that it is equipped with an electrical correction circuit that corrects the output of each light receiving section according to the degree of attenuation of each beam within the waveguide member. There is a particular thing.

Another feature of the semiconductor laser device of the present invention is that the light receiving area of each light receiving portion is determined depending on the degree of attenuation of each beam within the waveguide member.

(E) Effect According to the present invention, for a beam with a large degree of attenuation within the waveguide member, the output of the corresponding light receiving part is electrically increased or the area of the corresponding light receiving part is increased,
As a result, differences in the degree of attenuation within the waveguide member are compensated for.

(F) Embodiment FIG. 1 shows the structure of a first embodiment of the present invention, and FIG. 2 shows an electric circuit diagram thereof. Referring to FIG. 1, the heat sink 20 is made of a semiconductor such as silicon or a good heat dissipator such as metal, and the semiconductor laser means LD and the waveguide member 8 are fixed to the surface thereof via an indium solder layer. Such a heat sink 20 is fixed to the horizontal surface of an L-shaped copper block 21,
On the other hand, a monitoring light receiving means PD is fixedly arranged on the vertical surface of the copper block 21.

The semiconductor laser means LD includes first to third laser beam generation sources 1 to 3, and each of these sources includes:
Parallel laser beams can be emitted in two directions with distances between the optical axes 4 at intervals of 100 μm. Each of the sources 1 to 3 is independently driven and is either constructed from a separate laser diode chip or is constructed integrally in monolithic form.

The waveguide member 8 has first to second beams corresponding to each of the above beams.
It includes third waveguide grooves 9 to 11. Second waveguide groove 1
0 is aligned with the optical axis 4 of the second source 2,
It extends in the direction of its optical axis. first and third waveguide grooves 9,
11 are aligned with the respective optical axes 4 of the corresponding first and third sources 1 and 3 on their entrance sides, but their exit sides are biased outward. As a result, each beam in one direction emitted from the semiconductor laser means LD is
oriented in mutually discrete directions. The waveguide member 8 is made of silicon, and is created by forming grooves 9 to 11 by etching and depositing a light reflecting material such as gold on the inner wall surface of the grooves. The appropriate width of each groove 9 to 11 is 60 μm.

The light receiving sections 5 to 7 are formed on a common silicon substrate by diffusion, and constitute a normal photodiode. The light-receiving area of the light-receiving sections 5 to 7 is approximately equal to the width of each waveguide groove of the waveguide member 8.

Referring to FIG. 2, the first to third light receiving sections 5 to
After each output of 7 is detected by the detection unit 30, it is compared with the common reference voltage Vc by the comparison unit 31, and based on the comparison result, the drive unit 32 selects the corresponding generation source 1 to 3.
drive. Note that the detection unit 30 is a fixed resistor 40.
and a variable resistor 41, the comparing section 31 mainly includes an operational amplifier 42, and the driving section 32 mainly includes a transistor 43, which are themselves of well-known configuration.

Each waveguide groove 9 to 11 of the waveguide member 8 shown in FIG.
The beam intensity derived from the second waveguide groove 10 is the highest for the reason described above, and the beam intensity derived from other areas is small due to attenuation within the waveguide groove. Therefore, depending on the degree of attenuation, each detection unit 30
variable resistor 41 is adjusted. That is, the resistance value of the variable resistor 41 is adjusted so that the same output is obtained at the output terminal 50 of each detection section 30 in a state where each of the beam generation sources 1 to 3 generates a beam of the same intensity. . As a result, differences in attenuation within each waveguide groove 9 to 11 are compensated for, allowing accurate monitoring operation.

In addition, the configuration of the detection unit 30 can also be a circuit whose amplification degree can be adjusted by using a transistor, an operational amplifier, or the like.

FIG. 3 shows the characteristic parts of the second embodiment of the present invention. In this case, the light receiving area of each light receiving section 5-7 is set according to the degree of attenuation within each waveguide groove 9-11. That is, the light-receiving area of the second light-receiving section 6 corresponding to the second waveguide groove 10 with the least attenuation is made the smallest to reduce the amount of light incident thereon, and each of the beam generation sources 1 to 3 emits the same intensity beam. In the situation that occurs,
Each of the light receiving sections 5 to 7 is made to give the same output value.
In this case, the output adjustment using the variable resistor 41 described in FIG. 2 is not necessary.

(g) Effects of the invention According to the invention, there is provided a semiconductor laser means including a plurality of laser beam generation sources that emit laser beams in two directions, and a semiconductor laser means that directs each of the laser beams emitted in one direction to directions that are discrete from each other. In a semiconductor laser device including a waveguide member having a plurality of oriented waveguide grooves and a plurality of monitoring light receiving sections that individually receive each laser beam emitted from the waveguide member, This compensates for the attenuation of the beam intensity at

[Brief explanation of the drawing]

Figures 1 and 2 show a first embodiment of the present invention, Figure 1A is a sectional view taken on a horizontal plane, Figure 1B
1B-1B line sectional view, Figure 2 is an electric circuit diagram,
FIG. 3 is a sectional view showing a second embodiment of the present invention, FIG. 4 is a plan view showing a conventional example, and FIG. 5 is a sectional view showing another conventional example. LD... Semiconductor laser means, 1-3... Laser beam generation source, PD... Light receiving means, 5-7... Light receiving section, 8... Wave guide member, 9-11... Wave guide groove.

Claims (1)

[Claims for Utility Model Registration] (1) Semiconductor laser means including a plurality of laser beam generation sources that emit laser beams in two directions, and directing each of the laser beams emitted in one direction in discrete directions. A waveguide member including a plurality of waveguide grooves, a plurality of monitoring light receiving sections that individually receive each laser beam derived from the waveguide member, and an output of each of these light receiving sections is transmitted into the waveguide member. A semiconductor laser device comprising an electrical correction circuit that corrects according to the degree of attenuation of a corresponding beam. (2) Semiconductor laser means including a plurality of laser beam generation sources that emit laser beams in two directions, and a plurality of waveguide grooves that direct the laser beams emitted in one direction in discrete directions. It is equipped with a waveguide member and a plurality of monitoring light-receiving parts that individually receive each laser beam derived from the waveguide member, and the light-receiving area of each of these light-receiving parts is the same as that of the corresponding beam within the waveguide member. A semiconductor laser device characterized in that the degree of attenuation is determined according to the degree of attenuation.