JPH11186658A - Semiconductor laser device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-wavelength semiconductor laser device wherein the heat of laser elements is well radiated to reduce the deterioration of the temp. characteristics and the assembling is easy. SOLUTION: Laser elements A, B are closely disposed and fixed on mount faces 52A, 52B of a sub-mount 50, intersecting at about 90 deg. and has light emitting positions 40A, 40B adjacent to a ridge line 56 near the mount sides of substrates 10A, 10B. If the distances L1, L2 from the chip side faces 36A, 36B at the ridge line 56 of the laser elements A, B to the emitting positions 40A, 40B are each about 50 μm, the distance L3 between these positions 40A, 40B can be easily 10 μm or less, thus transferring the heat produced at the emitting positions 40A, 40B to the sub-mount 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser device including a semiconductor laser device for outputting a plurality of different modes of laser light, and for example, a semiconductor laser suitable for an optical pickup for CD-R, DVD, or MD. It relates to improvement of the device.

[0002]

2. Description of the Related Art A semiconductor laser device is generally used as a light source of an optical pickup used for reproducing a disk such as a CD-R or a DVD. The emission wavelength of the laser element is different for CD-R and DVD. That is, DVD
While a short-wavelength visible laser in the 635 nm to 650 nm band is used for reproduction, a near-infrared laser in the 780 nm band is used for CD-R reproduction. As described above, although the wavelength of the laser light used is different, a single player can use a CD or CD-ROM.
It is advantageous to be able to play various discs such as R and DVD. Therefore, in order to enable reproduction of these various discs, an optical pickup incorporating a light source having two wavelengths of 650 nm / 780 nm is being studied.

On the other hand, in an MD player, when recording a signal with respect to a semiconductor laser device of an optical pickup, an equation (1) is used.
A high output of about 0 mW and a small output of about several mW when reading signals are required. In reading a signal, it is also required that the return light noise is small. In order to increase the return light noise, the coherence of the laser output light may be reduced. For this reason, in a semiconductor laser device for CD, self-excited oscillation is used as a measure against return optical noise.

However, a general self-excited oscillation laser cannot obtain linearity of light-current (IL) characteristics up to a high output range. For this reason, the practical high power limit is low, so that these laser devices cannot be used for MD. For this reason, a normal steady-state laser (non-self-excited oscillation laser) having a high output limit is used for the MD, and a high-frequency superposition is applied by an additional circuit at the time of low-output reading, so that the laser output light can be used. A technique for reducing coherence has been adopted. However, also in this case, if a two-wavelength light source of a self-pulsation laser element and a high-output laser element with a high output limit is built in, an optical pickup for MD can be used without requiring an additional circuit for superimposing high frequency. It becomes possible to configure.

[0005] Such a two-wavelength laser device includes:
For example, there is a proximity two-beam hybrid type laser array disclosed in a preprint of "Spring Applied Physics Related Lectures", 1988, "30p-ZQ-3". In this method, two semiconductor laser elements are fixed to individual blocks by a solder via a submount so that a light emitting region is a top portion, and the blocks are arranged to face each other such that the light emitting regions face each other. is there. Thereby, two independently operable laser elements having different wavelengths are arranged close to each other.

[0006]

However, the above background art has the following disadvantages. (1) The mounting is performed so that the light emitting region is on the top, in other words, the substrate side of the laser element is on the block side. For this reason, the light emitting region that generates heat is located at a position distant from the block. Therefore, heat is not sufficiently released,
There is a possibility that the temperature characteristics may be deteriorated. (2) Assembly work is complicated and difficult, such as mounting two laser elements on separate blocks and then arranging the laser elements back to back while adjusting their positions.

The present invention focuses on the above points,
It is an object of the present invention to provide a two-wavelength semiconductor laser device that satisfactorily dissipates heat from a laser element, reduces deterioration in temperature characteristics, and is easy to assemble.

[0008]

In order to achieve the above object, the present invention relates to a semiconductor laser device having a plurality of semiconductor laser devices having a stripe structure mounted on a submount, wherein the stripe structure is replaced by a chip of the semiconductor laser device. While being formed at a position deviated from the center, a plurality of mounting surfaces that intersect at substantially 90 degrees are formed on the submount, laser light is emitted substantially in parallel, and the laser light emission position is at the mounting surface side. The semiconductor laser device is disposed on the mounting surface such that the mounting surface is located at a position close to an intersecting ridge line. According to one of the main modes, the interval between the laser beams is set to 100 μm or less.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

[0010]

Embodiments of the present invention will be described below in detail. First, the semiconductor laser device according to the present embodiment will be described with reference to FIG. In the figure,
On the main surface of the n-type GaAs substrate 10, a first cladding layer 12, an active layer 14, and a second cladding layer 16 are sequentially laminated. An insulating layer 18 is formed on the cladding layer 16, and a stripe 20 exists on the insulating layer 18. Further, electrodes 22 and 24 are formed on each of the front and back surfaces.

The basic function of such a semiconductor laser device having a double heterostructure is the same as that of a well-known general device, and a current flows as shown by an arrow FA. This current flows into the stripe 20 by the insulating layer 18. Therefore, current flows only in a portion of the active layer 14 corresponding to the stripe 20, the carrier density in this portion increases, and the threshold current decreases.
A single mode stable laser oscillation indicated by an arrow FB is performed.

The stripe 20 is usually formed at the center of the chip. However, in this embodiment,
It is formed at a position biased to one of the chips.
Such a structure can be easily obtained only by changing the scribe line at the time of manufacturing. In the example of FIG. 3, the stripe 20 is formed so as to be deviated to the left of the figure. Therefore, the light emitting point 26 of the active layer 14 is not located near the center of the element but at a position corresponding to the stripe 20.

Next, referring to FIGS. 1A and 2,
The main configuration of this embodiment will be described. FIG. 1A is a front view of a main part, and FIG. 2 is a perspective view of the main part. In these figures, a semiconductor laser device A and a semiconductor laser device B
These devices output laser light of 650 nm band and 780 nm band, respectively. These are semiconductor laser devices having a double hetero (DH) structure having a general buried ridge stripe structure. And, in both cases, the substrates 10A, 10B
Is obtained by processing a wafer having the above-described double heterostructures 30A and 30B, which perform laser oscillation by the MOCVD method, grown and formed on the main surface into chips of a predetermined shape. Electrodes 32A, 34A, 32B and 34B are formed on the front and back, respectively.

On the other hand, the submount (radiator) 50 on which the laser elements A and B are mounted is formed by, for example, dicing a silicon substrate into a rectangular parallelepiped, and as shown in FIG. 52A and 52B are provided. The electrodes 54 are formed on the mount surfaces 52A and 52B by, for example, sputtering of Al or the like.

The chips of the laser elements A and B are arranged close to each other on the mounting surfaces 52A and 52B of the submount 50 so that the light emission directions are the same.
The 0A and 30B sides are fixed with a joining material using Sn as a brazing material. As a result, the heterostructure electrodes 34A and 34B of the laser elements A and B are connected to the submount electrode 54. After the mounting of the laser chip, wire bonding is performed at a predetermined location as shown in FIG. That is, the other electrodes 32A, 32B of the laser elements A, B
Are bonded to wires 38A and 38B by Au or the like, respectively. The driving voltage of the laser elements A and B is
The voltage is applied between the wires 38A and 38B and the electrode 54 on the submount side. The wires 38A and 38B are negative, and the electrode 54 is positive.

In this embodiment, the laser elements A and B
As shown in FIG. 3, the light emission positions 40A and 40B of
The configuration is biased toward one side of the chip. For this reason, the light emission positions 40A and 40B are positions close to the ridgeline 56 where the mounting surfaces 52A and 52B intersect at approximately 90 degrees. On the other hand, the active layers of the semiconductor laser devices A and B are located on the inside of the chip surface by only a few μm. That is, the light emission positions 40A and 40B are located near the surfaces of the substrates 10A and 10B.

Therefore, when the arrangement as shown in FIG. 1A is adopted, the chip side surface 36 on the side of the twill wire 56 of each of the laser elements A and B is used.
Distance L from A, 36B to light emitting positions 40A, 40B
If both L1 and L2 are about 50 μm, the distance L3 between the light emission positions 40A and 40B of both laser elements A and B is set to L3.
(≒ √2L1) can be easily reduced to 100 μm or less. Further, with such an arrangement, the laser elements A,
The light emission positions 40A and 40B of B are located on the submount 50 side. Therefore, the light emission positions 40A, 4A
The heat generated at 0B is transmitted to the submount 50 side, and the deterioration of the temperature characteristics is reduced.

As described above, according to this embodiment, the interval between the laser beams emitted almost in parallel from the light emitting positions 40A and 40B of the laser elements A and B can be narrowed, and the heat can be radiated well. Become like Also, the laser elements A and B may be attached along the ridgeline 56 of the mount 50, and subsequent alignment is not required, so that the workability and productivity of assembly are improved.

Note that, as shown in FIG.
When the angle at which A and 52B intersect is 90 degrees or more,
The distance between the light emitting positions 40A and 40B of the laser elements A and B,
That is, the laser beam interval becomes larger than in the above-described embodiment. Further, the intersection angle between the mounting surfaces 52A and 52B is set to 1
The interval when the laser elements A and B are arranged in parallel at 80 degrees is √2 times that of the present embodiment. However, since the submount 50 has a large volume, the heat radiation effect increases. Conversely, as shown in FIG. 1C, when the angle at which the mounting surfaces 52A, 52B intersect is 90 degrees or less, the laser elements A,
Although the distance between the light emitting positions 40A and 40B of B is smaller than that in the above-described embodiment, the heat radiation effect by the submount 50 is reduced. Therefore, as in the above-described embodiment, the intersection angle of the mount surfaces is preferably approximately 90 degrees.

There are many embodiments of the present invention, and various modifications can be made based on the above disclosure.
For example, the following is also included. (1) In the above embodiment, a ridge waveguide type laser device which can be manufactured by the MOCVD method is used, but various manufacturing methods, oscillation modes, device structures, etc. are known.
It is not limited to the above-described embodiment. The same applies to semiconductor materials and electrode materials used. (2) The present invention provides DVD, CD, CD-R compatible playback and M
D is a preferred application example, but is generally applicable if a plurality of laser beams having different modes are obtained.

(3) The semiconductor laser device A is set to a wavelength of 780 nm.
A self-sustained pulsating laser device that is self-oscillating at low power operation, and the semiconductor laser device B is a high-power laser device having a higher output limit than the semiconductor laser device A. Thus, an optical pickup for MD can be configured without requiring an additional circuit for high frequency superposition.

[0022]

As described above, according to the present invention,
The stripe structure is formed at a position deviated from the center of the chip of the semiconductor laser element, and a plurality of mounting surfaces that intersect the submant at approximately 90 degrees are formed, so that the laser light is emitted substantially in parallel, and the laser light emission position is The semiconductor laser device is arranged on the mount surface so as to be located on the mount surface side and at a position close to a ridge line at which the mount surface intersects. To reduce the deterioration of temperature characteristics,
A laser device that outputs two wavelengths of parallel laser light can be easily obtained with high productivity.

[Brief description of the drawings]

FIG. 1 is a front view of one embodiment of the present invention and a comparative example.

FIG. 2 is a perspective view showing a main part of the embodiment.

FIG. 3 is a perspective view showing an example of a semiconductor laser device in which a stripe is biased to one side of a chip.

[Explanation of symbols]

10, 10A, 10B ... substrates 12, 16 ... cladding layer 14 ... active layer 18 ... insulating layer 20 ... stripes 22, 24, 32A, 32B, 34A, 34B, 54 ...
Electrode 26 Light-emitting point 30A, 30B Heterostructure 36A, 36B Ripple-side chip side surface 38A, 38B Wire 40A, 40B Light-emitting position 50 Submount 52A, 52B Mounting surface 56 Ridge A, B Laser element

Claims (2)

[Claims] 1. A semiconductor laser device having a plurality of semiconductor laser elements having a stripe structure mounted on a submount, wherein the stripe structure is formed at a position deviated from the center of a chip of the semiconductor laser element. A plurality of mounting surfaces that intersect at 90 degrees are formed, and the laser light is emitted substantially in parallel, and the laser light emission position is on the mounting surface side and is a position close to a ridge line where the mounting surfaces intersect. A semiconductor laser device having the semiconductor laser element arranged on the mount surface as described above. 2. The semiconductor laser device according to claim 1, wherein an interval between the laser beams is set to 100 μm or less.