JPH05235486A - Multi-beam semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain easily a multi-beam semiconductor laser device of high performance, wherein the effects of the thermal interferences caused between respective single substantial laser elements are reduced, and the temperature of a chip is prevented from rising, and further, it can be kept constant. CONSTITUTION:A plurality of single substantial laser elements 11, 12,..., 13 are integrated in a monolithic way, separating from each other by predetermined distances, and a multi-beam semiconductor laser chip 1 is constituted. A plurality of Peltier elements 41 are provided on the top surface of a submount 2, separating from each other by predetermined distances. Then, the multi-beam semiconductor laser chip 1 is assembled in a joining-up way on the submount 2 via the Peltier elements 41.

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, and more particularly to parallel data transfer of an optical disk,
The present invention relates to a multi-beam semiconductor laser device used for ATM (Air turbine motor) node wiring in an exchange, interconnection of a supercomputer, and the like.

[0002]

2. Description of the Related Art FIG. 4 is an assembly sectional structural view of a conventional multi-beam semiconductor laser device for an optical disk reported in, for example, 1988 IEICE Research Group (OQE88-6, p39-44). 4 (a) shows the cross-sectional structure obtained by the junction-up assembly, and FIG. 4 (b) shows the cross-sectional structure obtained by the junction-down assembly. In the figure, 1 is a plurality of single laser elements (LD1, LD2, ..., LDn) 1
A multi-beam semiconductor laser chip in which 1, 12, ..., 13 are monolithically integrated, 2 is a heat sink (hereinafter referred to as a submount) which is a radiator, and 3 is a multi-beam semiconductor laser chip 1 and a submount 2 bonded together. .., 13 are soldering materials, respectively. Each of the single laser elements (LD1, LD
2, ..., LDn), 31, 32, and 33 are a front electrode, an active region, and a back electrode of each single laser element 11, 12 ,.

Next, the operation will be described. The multi-beam semiconductor laser device is an array laser that outputs a plurality of light by monolithically integrating a plurality of single laser elements at positions of light emitting points at equal intervals of several tens of μm to 250 μm. Each single laser element (LD1, LD
, ..., LDn) 11, 12, ..., 13 each independently have a p-electrode 31 and an n-electrode 33, and currents are independently injected into these, so that the single laser element 1
, 12, 13 operate independently and can output laser from each active region 32.

In such a monolithic multi-beam semiconductor laser device, each single laser element 11, 12,
.., 13 are integrated close to each other, so that when each single laser element operates at a high output of 30 mW or more, heat generated by laser oscillation causes thermal interference between the single laser elements. This thermal interference causes changes in the optical output, oscillation wavelength, etc. of the other single laser elements, making the operation unstable and causing a decrease in reliability of each single laser element due to temperature rise due to heat generation. Therefore, reduction of this thermal interference is important in the multi-beam semiconductor laser device.

The thermal interference generated between the individual laser elements changes depending on the method of assembling the multi-beam semiconductor laser device. Conventional semiconductor laser assembly methods include
As shown in FIG. 4A, a junction-up assembly (Ju) in which the back electrode 33 on the substrate side of the multi-beam semiconductor laser chip 1 and the heat sink 2 are fused by using the solder material 3
p assembly), and as shown in FIG. 4B, the surface of the front electrode 31 near the active region 32 and the heat sink 2 are connected to the solder material 3
Junction down assembly (J-do)
wn assembly).

FIG. 5 is a diagram for explaining a temperature rise in driving a conventional multi-beam semiconductor laser device. FIG. 5 (a) shows a case where each single laser element integrated on the multi-beam semiconductor laser chip 1 is operated alone, and all single laser elements (here, the total number of single laser elements is 4) are operated. The case shows the temperature rise. In the case of a multi-beam semiconductor laser device (when all the single laser elements are operated), unlike the single laser device, not only the heat generated by itself but also the temperature rise due to heat interference from other single laser elements, A single laser element LD2 located at the center of the multi-beam semiconductor laser chip 1
In the LD3, the number of single laser elements that give rise to thermal interference is larger than that of the single laser elements located at the ends, so the temperature rise rate is large.

FIG. 5B shows the temperature rise of a single laser element (central element) located in the central portion of the multi-beam semiconductor laser chip 1 and the single laser element integrated in the multi-beam semiconductor laser chip 1. , And the case where the multi-beam semiconductor laser device is operated at an output of P = 20 mW is shown here. As shown in the figure, the temperature of the central element rises as the number of integrated single laser elements increases. Further, as compared with the J-up assembly, the J-down assembly in which the surface close to the active region 32 serving as the heat source is fused to the heat-dissipating submount 2 has a smaller temperature increase rate, which is advantageous. I understand.

FIG. 6 is a diagram showing a light output-current characteristic which is one of the typical optical characteristics of a semiconductor laser. Here, for convenience, the number of single laser elements integrated in the multi-beam semiconductor laser chip 1 is four. I am trying. FIG. 6 (a) shows the optical output-current characteristics when each single laser element is driven independently, and FIG. 6 (b) shows the case where all single laser elements (LD1 to LD4) are driven simultaneously. There is. As shown in FIG. 6, it can be seen that when all the elements are driven at the same time, the optical output that is output with the same current is reduced as compared with the case where each single laser element is driven independently. Further, in the central elements LD2 and LD3 having a particularly high rate of temperature rise, the degree of decrease in light output is large.

As shown in FIG. 5 (a), in the case of the multi-beam semiconductor laser device, the temperature of the central element of the multi-beam semiconductor laser chip 1 is increased due to thermal interference from other single laser elements in addition to self-heating. , The central element LD has a constant driving current in all the single laser elements, as shown in FIG.
2, LD3 causes a decrease in light output. So APC
If an attempt is made to keep the optical output constant in all single laser elements by (auto-power control) driving, an increase in driving current causes a shift in oscillation wavelength. Therefore, in general, a J-down assembly is used for assembling the multi-beam semiconductor laser device so that thermal interference can be reduced as much as possible. Further, in order to improve the efficiency of heat diffusion, the submount 2 has a thermal conductivity. It uses good materials.

[0010]

Since the conventional multi-beam semiconductor laser device is constructed as described above, the J-down assembly is carried out in order to reduce the thermal interference between the individual laser elements. However, in order to J-down assemble a multi-beam semiconductor laser device in which each single laser element is electrically separated, a pattern electrode corresponding to each single laser element is also provided on the submount 2 side, and each single laser element is provided. It is necessary to assemble the laser elements with high precision so as not to short-circuit them, but there has been a problem that the assembling precision becomes strict as the number of single laser elements integrated on the multi-beam semiconductor laser chip increases. Further, the effect of thermal interference cannot be completely reduced even in the J-down assembly. Particularly, as the multi-beam semiconductor laser has a higher output or the number of integrated laser elements is increased, the thermal interference is further reduced. Since it is easy, the optical output is lowered, and the oscillation wavelength is also changed, so that there is a problem that the reliability is lowered.

The present invention has been made to solve the above problems, and is integrated on a chip in a multi-beam semiconductor laser device in which individual laser elements are electrically separated from each other. Even if the number of single laser elements to be used increases, thermal interference between the single laser elements does not increase, and the assembling work is easy, and the heat diffusion can be efficiently performed even if the J-up assembly is performed. The object is to obtain such a multi-beam semiconductor laser device.

[0012]

A multi-beam semiconductor laser device according to the present invention is a multi-beam semiconductor laser chip in which a plurality of single laser elements are monolithically integrated with a predetermined distance from each other, and on the upper surface thereof. A submount having a plurality of Peltier element elements provided at a predetermined distance, and a multi-beam semiconductor laser chip is junction-assembled on the submount via the plurality of Peltier element elements. ..

Further, in the multi-beam semiconductor laser device according to the present invention, in the above-mentioned multi-beam semiconductor laser device, the number of Peltier element elements and the number of single laser elements are the same, and the positions are opposite to each other at equal intervals. It is the one.

Further, the multi-beam semiconductor laser device according to the present invention is a multi-beam semiconductor laser chip in which a plurality of single laser elements are monolithically integrated with a predetermined distance from each other, and a predetermined surface region of the upper surface thereof. And a submount in which elements having the Peltier effect are formed by pn-junctions at intervals, and a multibeam semiconductor laser chip is junction-assembled on the submount.

Further, in the multi-beam semiconductor laser device according to the present invention, in the above-mentioned multi-beam semiconductor laser device, the maximum current is supplied to the Peltier element corresponding to the central portion of the multi-beam semiconductor laser chip or the element exhibiting the Peltier effect. The current corresponding to both ends is made to flow a minimum current.

[0016]

Since the multi-beam semiconductor laser device according to the present invention uses the submount provided with a plurality of Peltier elements which can be independently operated, the inter-unit laser elements integrated on the multi-beam semiconductor laser chip are separated from each other. Alternatively, it is possible to independently control the temperature in a region divided into a plurality of chips, the temperature distribution in the chip can be kept uniform, and a multi-beam semiconductor laser is mounted on a submount by J-up assembly. Since the chips are assembled, a multi-beam semiconductor laser device that is easy to assemble and has high reliability can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an assembled sectional structure of a multi-beam semiconductor laser device according to an embodiment of the present invention. In the drawing, 1 is a plurality of single laser elements (LD1,
LD2, ..., LDn) 11, 12, ..., 13 are monolithically integrated multi-beam semiconductor laser chips, 2
Is a heat-dissipating submount (heat sink) having a plurality of Peltier element elements 41 provided on the upper surface of the multi-beam semiconductor laser chip 1 and the Peltier element element 41, or Solder material for adhering the submount 2 and the Peltier element 41 to each other, and 11, 12, ...
1, LD2, ..., LDn, 31, 32, 33 are front electrodes, active regions, back electrodes of the individual laser elements 11, 12, ..., 13 and 41 is a multi-beam semiconductor laser chip 1.
And a Peltier element element inserted between the submount 2 and the submount 2.

FIG. 1A is a cross section of a multi-beam semiconductor laser in which the number of Peltier element elements 41 provided on the submount 2 is smaller than the number of single laser elements (n) in the multi-beam semiconductor laser chip 1. Structure
Further, in FIG. 1 (b), the number and position of the Peltier device elements 41 correspond to the number and position of the individual laser elements, that is, the numbers of both are the same and the positions are opposite to each other at equal intervals. 1 shows a cross-sectional structure of a multi-beam semiconductor laser in a case. The multi-beam semiconductor laser chip 1 in which a plurality of single laser elements are integrated on the submount 2 via the plurality of Peltier element elements 41 is J-up assembled. The Peltier element 41 is made to correspond to the number and position of each single laser element, as shown in FIGS. 1 (a) and 1 (b), according to the integration degree, the beam interval, and the laser light output. Or, the number of laser elements is set to be smaller than the number of single laser elements so as to correspond to a plurality of single laser elements.

Next, the operation will be described. The Peltier device element 41 utilizes the Peltier effect that heat and heat are generated at the interface between different metals when they are joined and an electric current is passed between the metals, and has a two-layer structure of different metals. There is. By passing an electric current through the Peltier element 41, there can be formed a side where an endothermic reaction occurs inside the Peltier element 41 to be cooled and a side where an exothermic reaction occurs to raise the temperature. The heat generating side is bonded to the sub-mount 2 side by bonding the one side to the multi-beam semiconductor laser chip 1 to suppress the temperature rise due to heat generation of the chip 1. The heat is radiated to. Also,
The Peltier device element 41 is formed by observing the multi-beam semiconductor laser device shown in FIG.
One or both sides of the element 41 are provided outside the semiconductor laser chip 1 and the submount 2, and the + and-electrodes of the element 41 are provided on the upper and lower surfaces of the portion exposed to the outside. Therefore, by changing the direction of the current flowing between these electrodes, the desired one of the two-layer metal constituting the Peltier element 41 can be used as the heat generating side or the heat absorbing side, and the Peltier element can be changed depending on the amount of current flowing. You can adjust the degree of effect.

In this embodiment, as in the conventional example, the individual laser elements 11, 12, ..., 13 are independently operated by injecting currents independently.
At this time, since the Peltier element 41 has a + electrode and a − electrode independently of each other, by changing the amount of current flowing in each element 41 and the direction of the current,
The temperature of the portion of the multi-beam semiconductor laser chip 1 that contacts the Peltier element 41 can be adjusted.

FIG. 2 is a diagram showing the relationship between the temperature rise and the amount of current applied to the Peltier element 41 when the multi-beam semiconductor laser device according to the embodiment of the present invention is driven. 8 point beam laser, the Peltier device element 41 has a single laser element LD1 as shown in FIG. 1 (b).
8 shows the case where eight LDs are provided corresponding to LD8. Hereinafter, the operation of adjusting the temperature rise by the Peltier element 41 will be described. 2 (a) shows the temperature rise in the multi-laser semiconductor chip 1 when the single laser elements LD1 to LD8 are simultaneously operated, and FIG. 2 (b) shows the Peltier element elements corresponding to the single laser elements LD1 to LD8. The amount of current applied to 41 is shown. As shown in the figure, conventionally, the temperature has risen with the single laser elements LD4 and LD5 in the central portion of the multi-beam semiconductor laser chip 1 as apexes. On the other hand, in this embodiment, as shown in FIG.
In the Peltier element element 41 corresponding to the elements LD4 and LD5 whose temperature easily rises, the Peltier element 4 corresponding to the elements LD1 and LD8 is maximum.
1, the amount of current flowing in the Peltier element element 41 is set so as to be the minimum, and the Peltier element element 41 is driven. Therefore, the cooling effect of the Peltier element element 41 becomes smaller toward the end of the multi-beam semiconductor laser chip 1. As a result, the temperature rise is suppressed toward the central portion of the chip 1, the temperature of all the single laser elements becomes constant, and the temperature rise rate of the whole is kept low.

As described above, in the above-described embodiment, the plurality of Peltier element elements 41 are independently provided on the submount 2, and the Peltier element elements 41 are different in the susceptibility to thermal interference depending on the position in the multi-beam semiconductor laser chip 1. The cooling effect of the Peltier element 41 is adjusted so that the temperature is uniform in all the parts of the chip 1 by adjusting the amount of current applied to the Peltier device element 41 corresponding to the part of the chip 1 at that part in the chip 1. Since the degree of is adjusted, it is possible to obtain a high-performance multi-beam semiconductor laser device with stable operation and reduced influence of thermal interference. Moreover, since the assembly can be performed by J-up assembly, the assembly can be easily and accurately performed even if the number of single laser elements integrated in the multi-beam semiconductor laser chip 1 increases. Further, in the second embodiment of FIG. 1 (b) in which the Peltier element elements 41 are provided in correspondence with the number and position of each single laser element, the number and position are not shown in FIG.
As compared with the first embodiment (a), the temperature in the same multi-beam semiconductor laser chip 1 can be made more uniform.

In the above embodiment, each Peltier element 41 is provided on the submount 2 in a hybrid manner, but as shown in FIG. 3, a semiconductor material (for example, Si) is used for the submount, Providing a p-type region and an n-type region, the Peltier device element 4 is monolithically
The same effect can be exhibited even with a stack of 1s, and a description will be given below of such a stack.

FIG. 3 is a view showing an assembled sectional structure of a multi-beam semiconductor laser device according to a third embodiment of the present invention. In the figure, the same reference numerals in FIG. 1 designate the same or corresponding parts. In FIG. 3, 52 is an n-type region formed by diffusing n-type impurities in a Si submount, 51 is a p-type region formed in the n-type region 52, and the single laser elements 11, 12, ..., When a current is passed between the electrode of 13, the p-type region 51, and the n-type region 52, the p-type region 51 and the n-type region 52
A Peltier effect between the p-type region 51 and the n-type region 52
Thus, the Peltier element 41 is formed.
As a result, by adjusting the direction and magnitude of the current, the single laser elements 11, 12, ...
The temperature of the back electrode 33 of No. 3 can be adjusted, and as a result, the temperature of the multi-beam semiconductor laser chip 1 can be adjusted.

In both of the above embodiments, the amount of current flowing through the Peltier device element 41 is controlled by providing a single thermistor for each single laser element 11, 12, ..., 13 or each Peltier device element 41, or
If the control is performed while monitoring the oscillation wavelength or the optical output of each single laser element 11, 12, ..., 13, the control accuracy can be further improved, and the stable multi-beam in which the influence of thermal interference is reduced. A semiconductor laser device can be obtained.

[0026]

As described above, according to the multi-beam semiconductor laser device of the present invention, when the multi-beam semiconductor laser chip is assembled, the Peltier element elements are divided into the same number as the number of single laser elements. Since the multi-beam semiconductor laser chip is assembled on the submount by J-up assembly, by controlling and operating each Peltier element independently, each single laser element is divided into a plurality of divided regions. The temperature can be controlled independently, and the temperature distribution in the chip can be kept uniform. Further, even if the J-up assembly is performed, the heat generated in the chip can be efficiently diffused. Therefore, even if the number of single laser elements integrated on the chip is increased, the assembly accuracy is not required so much. Further, the J-up assembly reduces the stress on the active region due to the J-down assembly, and as a result,
There is an effect that it is possible to easily obtain a high-performance multi-beam semiconductor laser device in which the influence of thermal interference between the individual laser elements is greatly reduced.

Further, if the Peltier element is provided in correspondence with the number and position of each beam element, temperature control can be performed more accurately, and a high-performance multi-beam semiconductor laser device can be obtained. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a diagram showing an assembled sectional structure of a multi-beam semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a temperature rise and a current amount applied to a Peltier device element during driving of a multi-beam semiconductor laser device according to an embodiment of the present invention.

FIG. 3 is a view showing an assembled sectional structure of a multi-beam semiconductor laser device according to a second embodiment of the present invention.

FIG. 4 is a view showing an assembled sectional structure of a conventional multi-beam semiconductor laser device.

FIG. 5 is a diagram showing a temperature rise when a conventional multi-beam semiconductor laser device is driven.

FIG. 6 is a diagram showing an optical output-current characteristic of a conventional multi-beam semiconductor laser device.

[Explanation of symbols]

 1 Multi-Beam Semiconductor Laser Chip 2 Submount (Heat Sink) 3 Solder Material 11 Single Laser Element (LD1) 12 Single Laser Element (LD2) 13 Single Laser Element (LDn) 31 Front Electrode 32 Active Region 33 Back Electrode 41 Peltier Element Element 51 p-type region 52 n-type region

[Procedure amendment]

[Submission date] May 14, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Further, the multi-beam semiconductor laser device according to the present invention includes a multi-beam semiconductor laser chip in which a plurality of single laser elements are monolithically integrated with a predetermined distance from each other, and a surface region of the upper surface thereof.
It is a semiconductor material in which a p-type region or an n-type region having a Peltier effect with the back electrode of the semiconductor laser chip is formed .
A et consisting submount is made by junction-up assembled multi-beam semiconductor laser chip on the submount.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction content]

FIG. 3 is a view showing an assembled sectional structure of a multi-beam semiconductor laser device according to a third embodiment of the present invention. In the figure, the same reference numerals in FIG. 1 designate the same or corresponding parts. In FIG. 3, reference numeral 52 is an n-type region formed by diffusing n-type impurities in a Si submount, 51 is a p-type region formed in the n-type region 52, and the p-type region 51 and the single laser element 11 are shown. , 12, ..., back electrodes 33 of 13 ,
When a current is passed between the n-type regions 52, a Peltier effect is generated between the back electrode 33 and the p-type region 51 or the n-type region 52, and the back electrode
33 and the p-type region 51 or the n-type region 52 form the Peltier element 41. Thus, the temperature of the back electrode 33 of the single laser element 11, 12, ..., 13 to be joined can be adjusted by adjusting the direction and magnitude of the current, and as a result, the multi-beam semiconductor laser chip 1 can be adjusted. The temperature can be adjusted.

Claims (4)

[Claims] 1. A multi-beam semiconductor laser chip in which a plurality of single laser elements are monolithically integrated with a predetermined distance from each other, and a plurality of Peltier element elements provided on a top surface thereof with a predetermined distance from each other. A multi-beam semiconductor laser device, comprising: a sub-mount having the sub-mount, wherein the multi-beam semiconductor laser chip is junction-up assembled on the sub-mount via the plurality of Peltier element elements. 2. The multi-beam semiconductor laser device according to claim 1, wherein the Peltier element element and the single laser element have the same number and the positions are opposite to each other at equal intervals. Laser device. 3. A multi-beam semiconductor laser chip in which a plurality of single laser elements are monolithically integrated at a predetermined distance from each other, and an element which exhibits a Peltier effect by a pn junction at a predetermined interval in a surface region of an upper surface thereof. A multi-beam semiconductor laser device, comprising: a sub-mount formed by forming a multi-beam semiconductor laser chip. 4. The multi-beam semiconductor laser device according to claim 1, wherein a maximum current is supplied to a Peltier element corresponding to a central portion of the multi-beam semiconductor laser chip or an element exhibiting a Peltier effect. A multi-beam semiconductor laser device characterized in that a minimum current is made to flow to those corresponding to both ends.