JP3148283B2 - Multi-beam semiconductor laser device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam semiconductor laser device having a plurality of light-emitting portions, and more particularly to a multi-beam semiconductor laser device having a light-receiving element for monitoring in each light-emitting portion.

[0002]

2. Description of the Related Art This type of multi-beam semiconductor laser device is used for applications such as laser beam printers and reading / writing of magneto-optical disks. FIG. 3 is a perspective view of a conventional multi-beam semiconductor laser device of this kind. As shown in the figure, a laser pellet 30 is mounted on a heat sink 32, and a light receiving element pellet 3 for detecting the intensity of laser light emitted from the pellet to the outside of the apparatus.
1 is arranged behind the laser pellet 30. In the example shown here, the laser pellet has three light emitting portions, and the light receiving element pellet 31 has three light emitting portions correspondingly.
The photodiodes are formed.

In order to drive a plurality of semiconductor lasers independently, it is necessary that light emitted from a plurality of light-emitting portions be incident on individual photodiodes without being mixed. An optical waveguide 33 connecting between the two pellets is provided between the light-receiving pellet 31 and the light-receiving pellet 31 (Sanyo Technical Review Vol. 2).
0, No. 1, pp. 7-13, 1988)

Alternatively, in order to separate one set of a light emitting unit and a photodiode from another set in place of the optical waveguide,
There were partitions between pairs.

[0005]

In the above-mentioned conventional example,
Since it is necessary to couple the light emitting unit and the light receiving element with an optical waveguide or to separate them from each other by a partition, there is a problem that the number of parts increases. Also,
The assembly also required precision, making it difficult to manufacture, and the yield did not increase.

[0006]

SUMMARY OF THE INVENTION A multi-beam semiconductor laser device according to the present invention comprises a plurality of semiconductor laser pellets or a plurality of semiconductor laser pellets each having a plurality of light emitting portions, each of which can be independently driven; And the same number of light receiving elements corresponding to are contained in the same package, and each light receiving element has a filter, and the selectivity of each filter and
The angle of incidence of the emitted light on the filter of the light receiving element is
Even if the oscillation frequency of
The emitted light can pass through the filter of the corresponding light receiving element.
When adjacent light emitting units oscillate at the same frequency
Even if the light emitted from each light emitting unit is
It is configured to transmit only the filter of the element .
This filter is constituted by, for example, a multilayer interference film.

[0007]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. This embodiment is an example in which two semiconductor laser pellets each having one light emitting unit and two light receiving element pellets each having one light receiving unit are provided.

To assemble the laser device of the present embodiment,
The screened non-defective semiconductor laser pellets 3 a and 3 b are die-bonded on the heat sink 2 on the package 1 using the solder 4. As the solder material for die bonding, a material obtained by extending In to a thickness of 5 μm is used. Similarly, the light receiving element pellets 5a and 5b for monitoring are packaged in the package 1.
Mount on top. Subsequently, the bonding wire 7 connects between the electrode portion of each pellet and the electrode 6 of the package.

Here, the semiconductor laser pellets 3a, 3b
Use AlGaInP-based visible light laser pellets having the same oscillation frequency. These two semiconductor laser pellets and two light receiving element pellets can all be independently electrically driven. When driving the laser one by one, the oscillation wavelength of the output 5mW are both 671.0Nm, when simultaneously 5 m W driven both by thermal mutual interference, the two lasers together oscillation wavelength 0.6nm Shift to longer wavelength side.

As shown in FIG. 2, the surface of the semiconductor substrate 5 for the light-receiving element pellet is coated with a multilayer thin film by vacuum evaporation. The breakdown of the multilayer thin film is, in order from the surface of the semiconductor substrate 5, cryolite (N
a ₃ AlF ₆ , a refractive index of 1.35) 8 and three layers of zinc sulfide (ZnS, refractive index of 2.4) 9 having a thickness of 700 ° are provided,
After depositing 2486 mm of cryolite 8 thereon, another 700 mm thick zinc sulfide 9 and 1243 mm thick cryolite 8 were deposited thereon.
Are laminated three by three.

This multilayer thin film has a center value of a transmission wavelength of 671 n with respect to light vertically irradiated on the light receiving element pellet.
m, a narrow band filter having a half width of 1 to 2 nm is configured.

Since the size of the light emitting portion of the laser is very small (5 μm × 1 μm), the angle of light incident on the light receiving element pellet depends on the size of the light receiving element pellet.
Here, the size of the light receiving element pellet is 100 μm × 100
Assuming that the distance between the laser pellet 3a (3b) and the light receiving element pellet 5a (5b) is 3 mm, the angle θ ₁ of the laser beam incident on the light receiving element pellet 5a from the laser pellet 3a is 0. ° ≦ θ ₁ ≦ 1.35
° (the maximum angle is the angle at the corner). The same applies to the laser pellet 3b and the light receiving element pellet 5b.

On the other hand, the incident angle θ ₂ from the laser pellet 3a to the light receiving element pellet 5b is
When the distance between the centers of a and 5b is 0.5 mm, 8.5 ° ≦
θ ₂ ≦ 10.5 ° (the minimum angle is at the side, and the maximum angle is at the corner).

[0014] The above-mentioned filter has a relation of Δ
A filter having a wavelength shifted by λ = (1 / cos θ′−1) λ as a center transmission region.
Here, θ ′ is the refraction angle (sin θ / sin θ ′ = 1.35). Therefore, in the above range of θ ₂ , the wavelength shift Δλ is:
Since 4.1 nm ≦ Δλ ≦ 6.2 nm, the laser beam incident on the light receiving element pellet 5b from the laser pellet 3a is not received even if the oscillation wavelength is shifted to the longer wavelength side by parallel driving. Similarly, laser light incident on the light receiving element pellet 5a from the laser pellet 3b is not received.

In this way, the semiconductor laser pellet 3
The laser beam intensity of a is determined by the photocurrent of the light receiving element pellet 5a, and the laser beam intensity of the laser pellet 3b is
It can be monitored by the photocurrent of the light receiving element pellet 5b, and the two semiconductor lasers can be driven independently. In fact, according to the present embodiment, the crosstalk between the respective light receiving element pellets could be reduced to 1% or less.

In the above embodiment, two laser pellets having one light emitting portion are used. However, a laser pellet having a plurality of light emitting portions and capable of independently driving each light emitting portion is used. Can be replaced. Further, as the light receiving element, a pellet having a plurality of light receiving portions that can be driven independently can be used. In the above embodiment, the two light emitting units oscillate at the same frequency. However, the present invention is not limited to this, and a plurality of light emitting units emit laser beams having different wavelengths. May be used. In that case, it is necessary to make the center value of the filter of each light receiving element different.

[0017]

As described above, the multi-beam semiconductor laser device of the present invention is provided with an incident angle selectable or wavelength selectable filter for each light receiving element for monitoring. For example, it is possible to receive only the light of the light emitting section corresponding to each light receiving element without using an optical waveguide or a partition. Therefore, according to the present invention, a multi-beam laser device capable of independently monitoring a plurality of light-emitting portions can be realized with a small number of parts and without requiring a complicated assembly process. The yield can be improved and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a filter structure of a light receiving element used in the embodiment of FIG.

FIG. 3 is a perspective view of a conventional example.

[Explanation of symbols]

1 ... package, 2 ... heat sink, 3a, 3
b: semiconductor laser pellets, 4: solder, 5:
Semiconductor substrate, 5a, 5b ... light receiving element pellet,
6 ... electrode, 7 ... bonding wire, 8 ... cryolite, 9 ... zinc sulfide, 30 ... laser pellet,
31: light receiving element pellet, 32: heat sink,
33 ... Optical waveguide.

Claims (2)

(57) [Claims] 1. A semiconductor laser pellet having a plurality of semiconductor laser pellets or a plurality of light-emitting portions, and a filter provided for each light-emitting portion and each transmitting light emitted from the corresponding light-emitting portion. a plurality of light receiving elements are, Maruchibi that but housed in the same package
In a semiconductor laser device, the selectivity of each of the filters
And a filter of the light receiving element for the light emitted from the light emitting unit
The angle of incidence to the
However, the light emitted from the light emitting part is
And the adjacent light emitting parts are the same
Even when oscillating at a frequency,
The emitted light will only pass through the filter of the corresponding light receiving element.
A multi-beam semiconductor laser device characterized by being selected as follows . 2. The multi-beam semiconductor laser device according to claim 1, wherein said filter comprises a multilayer interference film.