JP2021132089A - Semiconductor laser device - Google Patents

Abstract

To provide a highly reliable multi-wavelength semiconductor laser device.SOLUTION: An embodiment of a semiconductor laser device is a semiconductor laser device in which a plurality of semiconductor laser elements having different oscillation wavelengths from each other are electrically connected in series, and at least one of the volume of the gain region in the plurality of semiconductor laser elements and the total length in the direction of progression of the relaxation region in which the optical confinement is relaxed at the edge of the semiconductor laser elements, are different from each other.SELECTED DRAWING: Figure 2

Description

The present invention relates to a semiconductor laser device.

In recent years, semiconductor laser devices having a longer life have come to be used as light sources for displays such as projectors, as opposed to lamps that have been conventionally used. However, since the laser light is coherent light, speckle-like noise called speckle is generated on the screen. This reduction in speckle is required for semiconductor laser devices for displays.

There are several measures to reduce the speckle, and one of them is to use a plurality of semiconductor laser elements having different oscillation wavelengths in the range of several nm to several tens of nm. In order to reduce speckle by this measure, there is a demand for a device equipped with a plurality of semiconductor laser elements included in the same wavelength band but different in oscillation wavelength. For example, in the case of the red wavelength band, there is a demand for a device having not only a semiconductor laser element having an oscillation wavelength of 638 nm but also a semiconductor laser element having an oscillation wavelength of 640 nm, 642 nm, ..., 660 nm and the like.

This speckle reduction can be achieved by preparing semiconductor laser devices in which semiconductor laser devices with different oscillation wavelengths are mounted in different packages, but in order to reduce the size of the device, multiple semiconductor laser devices with different oscillation wavelengths can be realized. Is preferably mounted in one package. Further, mounting a plurality of semiconductor laser elements having different oscillation wavelengths in one package leads to cost reduction as compared with mounting semiconductor laser elements having different oscillation wavelengths in different packages.

For example, Patent Document 1 discloses an apparatus in which a plurality of semiconductor laser elements are arranged on one submount, and describes that the plurality of semiconductor laser elements may be in the same wavelength band or different wavelength bands. ing. Further, Patent Document 1 describes that when a plurality of semiconductor laser elements are arranged, they may be connected in series.

Further, for example, Patent Document 2 discloses a structure in which a plurality of heat sinks (submounts) are arranged in the longitudinal direction of a support block and laser chips are arranged in each heat sink, and the plurality of laser chips are electrically connected in series. It is also disclosed that it will be connected.

Japanese Patent No. 6361293 Special Table 2016-518726

When a plurality of semiconductor laser elements having different oscillation wavelengths are mounted in one package, it is desirable to mount them in series because of the mounting space and wiring structure. Then, the same current flows through the plurality of semiconductor laser elements connected in series.

However, in the case of a GaAs-based red laser, for example, the oscillation wavelength is adjusted by the strain amount of the active layer. Is etc. change. As a result, when viewed at a constant drive current in a package in which a plurality of semiconductor laser elements are mounted, the light output differs between the semiconductor laser elements. Further, as the oscillation wavelength becomes longer, the heterobarrier between the active layer and the p-clad layer becomes higher, and electron overflow is less likely to occur, so that the temperature characteristics are improved. As a result, the higher the operating conditions of the semiconductor laser device and the larger the current, the larger the difference in light output due to the difference in oscillation wavelength in the plurality of semiconductor laser elements.

For this reason, when semiconductor laser elements with different oscillation wavelengths are driven by the same current, the light output tends to differ, and in general, the higher the light output, the more the end face deterioration progresses. The life will vary, leading to a decrease in the reliability of the semiconductor laser device.
Therefore, an object of the present invention is to provide a highly reliable multi-wavelength semiconductor laser device.

In order to solve the above problems, one aspect of the semiconductor laser device according to the present invention is a semiconductor laser device in which a plurality of semiconductor laser elements having different oscillation wavelengths are electrically connected in series. The volumes of the gain regions in the plurality of semiconductor laser elements are different from each other.

When the number of carriers required to cause light amplification is constant per unit volume, the current required for laser oscillation depends on the volume of the gain region. Therefore, according to the semiconductor laser apparatus according to the present invention, since the oscillation threshold value of the semiconductor laser element can be adjusted by adjusting the volume of the gain region, a plurality of semiconductor lasers have a plurality of semiconductor lasers with respect to the optical output at the desired drive current of the semiconductor laser apparatus. Proximity is possible between the elements. Therefore, the variation in the life of the plurality of semiconductor laser elements is suppressed, and a highly reliable multi-wavelength semiconductor laser device can be obtained.

In the semiconductor laser apparatus, the plurality of semiconductor laser elements may have different widths of the gain regions in a direction intersecting the traveling direction of the laser beam. As such a form in which the widths of the gain regions are different from each other, it is preferable that the plurality of semiconductor laser elements have a ridge stripe structure and the ridge widths in the ridge stripe structure are different from each other.
The volume of the gain region can be adjusted by changing the width of the gain region, and the width of the gain region can be easily and accurately adjusted by changing the width of the ridge.

In the semiconductor laser apparatus, the plurality of semiconductor laser elements may have different lengths of the gain regions in the traveling direction of the laser beam. The volume of the gain region can also be adjusted by changing the length of the gain region.

In the semiconductor laser apparatus, the total length in the traveling direction of the relaxation region in which the light confinement in the direction intersecting the traveling direction of the laser light is loosened at the end of the semiconductor laser element is replaced with the volume of the gain region. Or, with the volume of the gain region, it is preferable that the plurality of semiconductor laser elements are different from each other. However, some semiconductor laser devices may have the above total length of zero.

Since the light confinement becomes weak and the light loss increases in the relaxation region, the oscillation threshold value of the semiconductor laser element can be adjusted by adjusting the length of the relaxation region. Therefore, the light output at the desired drive current of the semiconductor laser device can be brought close to each other by adjusting the length of the relaxation region. Therefore, the variation in the life of the plurality of semiconductor laser elements is suppressed, and a highly reliable multi-wavelength semiconductor laser device can be obtained.

In semiconductor laser devices having different lengths of relaxation regions, it is preferable that the plurality of semiconductor laser elements have a ridge stripe structure and no ridges are present in the relaxation region. The length of the relaxation region can be easily adjusted by adjusting the range in which the ridge is provided.

In semiconductor laser devices having different lengths of relaxation regions, the plurality of semiconductor laser elements may have a ridge stripe structure, and the width of the ridges in the relaxation region may be wider than that of other portions. A wide ridge also provides a relaxation area.

Further, in the semiconductor laser device according to the present invention, it is preferable that the plurality of semiconductor laser elements have oscillation wavelengths in wavelength bands of the same color. By including the oscillation wavelength in the wavelength band of the same color, the speckle can be reduced.

According to the present invention, a highly reliable multi-wavelength semiconductor laser device can be obtained.

It is a figure which shows the 1st Embodiment of the semiconductor laser apparatus of this invention. It is a figure which shows the laser chip on the submount. It is a graph which shows the input / output characteristic of the laser chip in the comparative example. It is a table which shows the resonator length of a laser chip. It is a graph which shows the input / output characteristic of the laser chip in 1st Embodiment. It is a figure which shows the laser chip on the submount in 2nd Embodiment. It is a figure which shows the ridge stripe structure in a laser chip. It is a table which shows the ridge width of a laser chip. It is a figure which shows the ridge stripe structure in the laser chip of 3rd Embodiment. It is a table which shows the length of the relaxation region in a laser chip. It is a graph which shows the input / output characteristic of the laser chip in 3rd Embodiment. It is a figure which shows the structure of the laser chip in 4th Embodiment. It is a figure which shows the structure of the laser chip in 5th Embodiment. It is a figure which shows the structure of the laser chip in 6th Embodiment. It is a figure which shows the structure of the laser chip in 7th Embodiment. It is a figure which shows the structure of the laser chip in 8th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a first embodiment of the semiconductor laser device of the present invention.

The semiconductor laser apparatus 100 includes a stem base 101, a stem block 102, and a plurality of (two in the example shown here) laser chips 103_1 and 103_2. The semiconductor laser device 100 may be an open type, but in the example shown in FIG. 1, it is a closed type provided with a stem cap 110.

The stem block 102 protrudes from the stem base 101, and the stem cap 110 is fixed to the stem base 101 to cover the stem block 102. The stem base 101, the stem block 102, and the stem cap 110 are all made of metal, and a can package is formed by these. The stem block 102 and the stem base 101 do not have to be made of the same material, and may be made of different materials, or a part of the stem base may be made of the material of the stem block. The reverse is also possible, and the present invention is not particularly limited.

In the stem block 102, a sub-mount 104 on which the laser chips 103_1 and 103_2 are mounted is fixed by solder to a part of the side surface rising from the stem base 101. The laser beam emitted from the laser chips 103_1 and 103_2 travels upward in FIG. 1, passes through the glass window 111 fitted in the stem cap 110, and is emitted from the semiconductor laser apparatus 100.

The heat generated by the laser chips 103_1 and 103_2 at the time of light emission is transferred to the stem block 102 via the submount 104, and further transferred from the stem block 102 to the stem base 101.

The laser chips 103_1 and 103_2 may be of a multi-emitter type that emits a laser beam of a plurality of spots, or may be a single-emitter type that emits a laser beam of a single spot. The laser chips 103_1 and 103_2 correspond to an example of the semiconductor laser device referred to in the present invention. The laser chips 103_1 and 103_2 in the present embodiment are, for example, laser chips using an AlGaInP-based semiconductor, but the semiconductor laser element referred to in the present invention may be a laser chip using a semiconductor other than the AlGaInP-based semiconductor. ..

In order to supply power to the laser chips 103_1 and 103_2, the semiconductor laser device 100 is provided with a power supply lead pin 105. One end of the power supply lead pin 105 penetrates the stem base 101 and protrudes into the stem cap 110.
The wire 106 is connected to the laser tips 103_1 and 103_2 from one end of the power feeding lead pin 105 protruding into the stem cap 110.
FIG. 2 is a diagram showing a laser chip on a submount.
Here, for convenience of explanation, the upper part of the figure is referred to as "upper" and the lower part of the figure is referred to as "lower" regardless of the direction of gravity.

Two laser chips 103_1 and 103_2 are mounted on the upper surface of the submount 104. Specifically, the laser chips 103_1 and 103_2 are fixed with solder. Each of the laser chips 103_1 and 103_2 has a front end 103a shown on the left front side in the figure and a rear end 103b hidden on the right back side in the figure, and emits a laser beam from the front end 103a.

Of the two laser chips 103_1 and 103_2, the first laser chip 103_1 has an oscillation wavelength of, for example, 643 nm, and the second laser chip 103_2 has an oscillation wavelength of, for example, 638 nm. Each oscillation wavelength is included in the red wavelength band of 550 nm or more and 700 nm or less. That is, these two laser chips 103_1 and 103_2 are included in the wavelength band of the same color (red in the example shown here) and have different oscillation wavelengths. Since the oscillation wavelengths of the two laser chips 103_1 and 103_2 are different in this way, the speckle is reduced in the laser beam emitted from the semiconductor laser apparatus 100 shown in FIG.

Each of the laser chips 103_1 and 103_2 has electrodes on the upper surface and the lower surface, and emits a laser beam when a voltage is applied between the upper and lower electrodes. The operating voltage of each of the laser chips 103_1 and 103_2 is 2 V or more and 4 V or less.

The two laser chips 103_1 and 103_2 are electrically connected in series by a wire 106 on the submount 104. Therefore, the drive voltage of the semiconductor laser device 100 is around 5 V. Due to such electrical series connection, a plurality of electrically partitioned electrode patterns 104a (two in the example shown here) are formed on the upper surface of the submount 104, and each of them is formed on each electrode pattern 104a. The laser chips 103_1 and 103_2 are mounted.

In the first embodiment, the lengths (particularly the resonator lengths) of the two laser chips 103_1 and 103_2 are different from each other, and the second laser chip 103_2 is longer than the first laser chip 103_1.

Here, the input / output characteristics are shown for a comparative example in which the resonator lengths of the two laser chips 103_1 and 103_2 are equal to each other. It is assumed that the resonator lengths of the laser chips 103_1 and 103_2 in the comparative example are the same as those of the second laser chip 103_2 in the first embodiment.
FIG. 3 is a graph showing the input / output characteristics of the laser chip in the comparative example.

The horizontal axis of FIG. 3 represents the input current value, and the vertical axis represents the optical output value. Further, the graph showing the input / output characteristics of the first laser chip 103_1 is shown by a dotted line, and the graph showing the input / output characteristics of the second laser chip 103_1 is shown by a solid line.

The first laser chip 103_1 and the second laser chip 103_2, which have different oscillation wavelengths, have different laser oscillation thresholds (that is, because the amount of distortion of the active layer is different even when the resonator lengths are equal to each other. The rising positions of the graphs) are different from each other, and the slopes of the graphs are also different. On the other hand, the two laser chips 103_1 and 103_2 electrically connected in series are driven by the same drive current value D. Further, the drive current value D for a light source for display applications is generally a preset constant value.

Therefore, as shown in FIG. 3, there is a possibility that an output difference ΔL may occur in the optical output values of the laser chips 103_1 and 103_2 at the same drive current value D. In the comparative example in which the resonator lengths are the same, such an output difference ΔL is large, so that the laser chip with the larger output (second laser chip 103_2 in the example of FIG. 3) has a shorter life, and the semiconductor laser apparatus 100 The reliability of the is reduced.

In contrast to such a comparative example, in the semiconductor laser apparatus 100 of the present embodiment, the resonator lengths of the two laser chips 103_1 and 103_2 are different from each other, and thus the difference in optical output between the two laser chips 103_1 and 103_2 is increased. It is suppressed.
FIG. 4 is a table showing the resonator length of the laser chip.

The upper part of FIG. 4 shows the resonator lengths of the first laser chip 103_1 and the second laser chip 103_2, respectively, and the lower part shows the second one based on the resonator length of the first laser chip 103_1. The cavity length of the laser chip 103_2 is shown.

The first laser chip 103_1 (that is, a laser chip having an oscillation wavelength of 643 nm) has a resonator length of, for example, 1385 μm, whereas the second laser chip 103_2 (that is, a laser chip having an oscillation wavelength of 638 nm) has a resonator length of, for example, 1540 μm. ing. Based on the resonator length of the first laser chip 103_1, the resonator length of the second laser chip 103_2 is 11% longer.

As a result, in the first embodiment, the volume of the gain region is different between the first laser chip 103_1 and the second laser chip 103_2, and specifically, the volume of the gain region in the first laser chip 103_1. Is smaller than the volume of the gain region in the second laser chip 103_2.

Generally, in order to obtain the light amplification effect in the gain region of the laser chip, it is necessary that the number of carriers per unit volume in the gain region exceeds a certain number. When the input current value to the laser chip reaches the current value (that is, the oscillation threshold value) capable of supplying the number of carriers exceeding a certain number, the laser oscillation is started. Therefore, if the other conditions are the same, the larger the volume of the gain region, the larger the total number of carriers required for oscillation and the higher the oscillation threshold, and the smaller the volume of the gain region, the larger the total number of carriers required for oscillation. It decreases and the oscillation threshold decreases.

In the first embodiment, since the resonator length of the first laser chip 103_1 is shorter than that of the above-mentioned comparative example, the volume of the gain region is small. Therefore, the oscillation threshold value of the first laser chip 103_1 is lower in the first embodiment than in the above comparative example.
FIG. 5 is a graph showing the input / output characteristics of the laser chip according to the first embodiment.

The horizontal axis of FIG. 5 represents the input current value, and the vertical axis represents the optical output value. Further, the graph showing the input / output characteristics of the first laser chip 103_1 is shown by a dotted line, and the graph showing the input / output characteristics of the second laser chip 103_1 is shown by a solid line.

In the first embodiment, the difference between the laser oscillation thresholds (that is, the rising positions of the graph) between the first laser chip 103_1 and the second laser chip 103_2 is narrower than that of the comparative example shown in FIG. As a result, the optical output value at the set drive current value D is substantially the same for the first laser chip 103_1 and the second laser chip 103_2. Therefore, the semiconductor laser device 100 of the first embodiment is a highly reliable device.

Hereinafter, other embodiments of the semiconductor laser device of the present invention will be described. However, in the following description, the description will be focused on the differences from the embodiments already described, and duplicate description will be omitted.
FIG. 6 is a diagram showing a laser chip on a submount according to the second embodiment.

In the second embodiment as in the first embodiment, the two laser chips 103_1 and 103_2 are mounted on the upper surface of the submount 104 and fixed by soldering. However, in the second embodiment, unlike the first embodiment, the resonator lengths of the two laser chips 103_1 and 103_2 are the same.

In the case of the second embodiment, since the width of the ridge described later is different between the first laser chip 103_1 and the second laser chip 103_2, the volume of the gain region is different from each other as in the first embodiment. There is.
FIG. 7 is a diagram showing a ridge stripe structure in the laser chip.
A plan view of the laser chips 103_1 and 103_2 is shown in the upper part of FIG. 7, and a cross-sectional view taken along the line AA is shown in the lower part.

The laser chips 103_1 and 103_2 have a structure in which an n-type semiconductor layer 121, an active layer 122, a p-type semiconductor layer 123, an insulating layer 124, and an electrode layer 125 are laminated in this order. A gain region 127 is formed in the active layer 122 by applying a voltage in the stacking direction from the n-type semiconductor layer 121 to the electrode layer 125 and causing a current to flow.

The insulating layer 124 covers the p-type semiconductor layer 123, but the insulating layer 124 does not cover the stripe region 130 along the extending direction of the optical resonator, and the electrode layer 125 is in contact with the p-type semiconductor layer 123. There is. The current flows through the stripe region 130 in the stacking direction (that is, in the vertical direction in the end view), and the edge of the stripe region 130 is formed by the ridge groove 126 along the extending direction of the optical resonator, so that the active layer The gain region 127 of 122 is formed in a range sandwiched by the ridge groove 126.

In the second embodiment, the thickness of each layer in the stacking direction is equal for the first laser chip 103_1 and the second laser chip 103_2. Therefore, the volume of the gain region 127 in the second embodiment is determined by the distance between the ridge grooves 126 (that is, the width of the ridge).
FIG. 8 is a table showing the ridge width of the laser chip.

The upper part of FIG. 8 shows the ridge widths of the first laser chip 103_1 and the second laser chip 103_2, respectively, and the lower part shows the second laser based on the resonator length of the first laser chip 103_1. The ridge width of tip 103_2 is shown.

The ridge width of the first laser chip 103_1 (that is, the laser chip having an oscillation wavelength of 643 nm) is, for example, 71 μm, whereas that of the second laser chip 103_2 (that is, the laser chip having an oscillation wavelength of 638 nm) is, for example, 80 μm. There is. Based on the ridge width of the first laser chip 103_1, the ridge width of the second laser chip 103_2 is 13% wider.

As a result, also in the second embodiment, the volume of the gain region is different between the first laser chip 103_1 and the second laser chip 103_2. Specifically, the volume of the gain region in the first laser chip 103_1 Is smaller than the volume of the gain region in the second laser chip 103_2.

In the second embodiment, since the ridge width of the first laser chip 103_1 is narrower than that of the above-mentioned comparative example, the volume of the gain region is small. As a result, the oscillation threshold value of the first laser chip 103_1 is lower in the second embodiment than in the comparative example, and is substantially the same as the oscillation threshold value in the first embodiment. Further, the input / output characteristics in the second embodiment are substantially the same as the input / output characteristics in the first embodiment shown in FIG. 5, and the optical output value at the set drive current value D is the same as that of the first laser chip 103_1. The values are almost the same as those of the second laser chip 103_2. Therefore, the semiconductor laser device 100 of the second embodiment is also a highly reliable device.

The stripe region 130 may be electrically formed only in the forming range of the insulating layer 124 and the electrode layer 125 without providing the ridge, and in that case, the volume of the gain region 127 is increased by the width of the stripe region 130. It is adjustable. The volume of the gain region 127 can also be adjusted by the thickness of the active layer 122.
Next, a third embodiment of the semiconductor laser device of the present invention will be described.
FIG. 9 is a diagram showing a ridge stripe structure in the laser chip of the third embodiment.
A plan view of the laser chips 103_1 and 103_2 is shown in the upper part of FIG. 9, and a cross-sectional view taken along the line AA is shown in the lower part.

In the third embodiment, unlike the second embodiment, the distance between the ridge grooves 126 is the same between the first laser chip 103_1 and the second laser chip 103_2, but in the third embodiment, the second laser chip 103_2 is used. , The ridge groove 126 is not provided at the end of the laser tip 103_2. On the other hand, since the stripe region 130 is formed beyond the extended range of the ridge groove 126 to near the end portion, the stripe region 130 is formed by the first laser chip 103_1 and the second laser chip 103_2 in the third embodiment as well. The lengths are about the same.

The ridge groove 126 has an effect of confining the light reciprocating in the optical resonator in the left-right direction of FIG. 9, and the light is confined within the confinement range 128. In the second laser chip 103_2, since the ridge groove 126 is not provided at the end of the laser chip 103_2, the light confinement at the end is loosened, and a relaxation region 131 in which the confinement range 128 is widened is generated. When the light confinement is loosened in this way, the light loss increases, so that more carriers are required to oscillate the laser, and the oscillation threshold becomes high.
FIG. 10 is a table showing the length of the relaxation region in the laser chip.

The upper part of FIG. 10 shows the length of the relaxation region 131 in each of the first laser chip 103_1 and the second laser chip 103_2, and the lower part shows the length of the second laser chip 103_2 based on the resonator length. The length of the relaxation region 131 is shown.

In the first laser chip 103_1 (that is, the laser chip having an oscillation wavelength of 643 nm), the length of the relaxation region 131 is, for example, 0 μm (that is, a ridge is formed up to the end face), whereas the second laser chip 103_2 (that is, a laser chip with an oscillation wavelength of 643 nm) That is, for a laser chip having an oscillation wavelength of 638 nm), it is, for example, 279 μm. Based on the resonator lengths of the laser chips 103_1 and 103_2, 0% of the first laser chip 103_1 is the relaxation region 131, and 18% of the second laser chip 103_2 is the relaxation region 131.

By forming the relaxation region 131 in this way, the second laser chip 103_2 in the third embodiment has an oscillation threshold value higher than the oscillation threshold value in the above-mentioned comparative example.
FIG. 11 is a graph showing the input / output characteristics of the laser chip according to the third embodiment.

The horizontal axis of FIG. 11 represents the input current value, and the vertical axis represents the optical output value. Further, the graph showing the input / output characteristics of the first laser chip 103_1 is shown by a dotted line, and the graph showing the input / output characteristics of the second laser chip 103_1 is shown by a solid line.

In the third embodiment, the laser oscillation threshold value of the second laser chip 103_2 rises, and the difference between the laser oscillation threshold values (that is, the rising position of the graph) between the first laser chip 103_1 and the second laser chip 103_2 increases. , It is narrower than the comparative example shown in FIG. As a result, the optical output value at the set drive current value D is substantially the same for the first laser chip 103_1 and the second laser chip 103_2. Therefore, the semiconductor laser device 100 of the third embodiment is also a highly reliable device.
Hereinafter, each embodiment having the relaxation region 131 will be described.
FIG. 12 is a diagram showing the structure of the laser chip in the fourth embodiment.
In each of the following figures, a plan view of the laser chips 103_1 and 103_2 is shown in the upper row, and a cross-sectional view taken along the line AA is shown in the lower row.

In the fourth embodiment shown in FIG. 12, unlike the third embodiment shown in FIG. 9, the length of the ridge groove 126 is the same in the first laser chip 103_1 and the second laser chip 103_2. On the other hand, since the stripe region 130 is formed beyond the extended range of the ridge groove 126 to near the end, in the first modification, the gain region is formed by the first laser chip 103_1 and the second laser chip 103_2. The volume is different. Specifically, the volume of the gain region in the second laser chip 103_2 is larger than the volume of the gain region in the first laser chip 103_1.

In the fourth embodiment, the relaxation region 131 is formed at the end of the second laser chip 103_2 as in the third embodiment, and unlike the third embodiment, the gain region in the second laser chip 103_2 is formed. The volume is large. As a result, the second laser chip 103_2 in the fourth embodiment is described above because the decrease in the oscillation threshold due to the increase in the volume of the gain region is smaller than the increase in the oscillation threshold due to the formation of the relaxation region 131. The oscillation threshold is higher than the oscillation threshold in the comparative example.
Therefore, in the fourth embodiment, the input / output characteristics of the second laser chip 103_2 are adjusted by the length of the relaxation region 131, and the highly reliable semiconductor laser device 100 can be obtained.
FIG. 13 is a diagram showing the structure of the laser chip in the fifth embodiment.

In the fifth embodiment, the width of the ridge groove 126 of the second laser chip 103_2 is tapered at the end. Therefore, the confinement range 128 also expands at the end to loosen the light confinement, and the relaxation region 131 is formed at the end. As described above, since the relaxation region 131 is formed even in the structure in which the width of the ridge groove 126 is widened at the end, the input / output characteristics of the second laser chip 103_2 are adjusted by the length of the relaxation region 131, and the reliability is improved. High-quality semiconductor laser device 100 can be obtained.
FIG. 14 is a diagram showing the structure of the laser chip in the sixth embodiment.

In the sixth embodiment, the width of the ridge groove 126 of the second laser chip 103_2 is widened in a stepped shape at the end. Therefore, the confinement range 128 also expands at the end to loosen the light confinement, and the relaxation region 131 is formed at the end. As described above, since the relaxation region 131 is formed even in the structure in which the width of the ridge groove 126 is widened in a stepped shape, the input / output characteristics of the second laser chip 103_2 are adjusted by the length of the relaxation region 131, and the reliability is improved. High-quality semiconductor laser device 100 can be obtained.
FIG. 15 is a diagram showing the structure of the laser chip in the seventh embodiment.

In the seventh embodiment, the width of the ridge groove 126 of the second laser chip 103_2 is tapered at the end. Further, the ridge groove 126 of the second laser chip 103_2 does not reach the end face, and a region without a ridge exists at the end. The tapered ridge groove 126 and the ridgeless region form a relaxation region 131 in which light confinement is loosened at the end of the laser chip 103_2. As described above, since the relaxation region 131 is formed even in the composite structure of the widening of the width of the ridge groove 126 and the region without the ridge, the input / output characteristics of the second laser chip 103_2 are adjusted by the length of the relaxation region 131. Therefore, a highly reliable semiconductor laser device 100 can be obtained.
FIG. 16 is a diagram showing the structure of the laser chip in the eighth embodiment.

In the eighth embodiment, the width of the ridge groove 126 of the second laser chip 103_2 is widened in a stepped shape at the end. Further, the ridge groove 126 of the second laser chip 103_2 does not reach the end face, and a region without a ridge exists at the end. Due to the stepped ridge groove 126 and the ridgeless region, the light confinement is loosened at the end of the laser chip 103_2, and the relaxation region 131 is formed. The input / output characteristics of the second laser chip 103_2 are adjusted by the length of the relaxation region 131, and a highly reliable semiconductor laser device 100 can be obtained.

100 ... semiconductor laser device, 101 ... stem base, 102 ... stem block,
103_1 ... 1st laser chip, 103_2 ... 2nd laser chip,
103a ... front end, 103b ... rear end, 104 ... submount, 104a ... electrode pattern,
105 ... power supply lead pin, 106 ... wire, 110 ... stem cap 121 ... n-type semiconductor layer, 122 ... active layer, 123 ... p-type semiconductor layer, 124 ... insulating layer,
125 ... Electrode layer, 126 ... Ridge groove, 127 ... Gain region, 128 ... Confinement range,
130 ... Striped area, 131 ... Relaxed area

Claims (8)

A semiconductor laser device in which a plurality of semiconductor laser elements having different oscillation wavelengths are electrically connected in series.
A semiconductor laser device characterized in that the volumes of gain regions in the plurality of semiconductor laser elements are different from each other. The semiconductor laser device according to claim 1, wherein the plurality of semiconductor laser elements have different widths of the gain regions in a direction intersecting the traveling direction of the laser light. The semiconductor laser device according to claim 1 or 2, wherein the plurality of semiconductor laser elements have a ridge stripe structure, and the ridge widths in the ridge stripe structure are different from each other. The semiconductor laser device according to any one of claims 1 to 3, wherein the plurality of semiconductor laser elements have different lengths of the gain regions in the traveling direction of the laser light. The total length in the traveling direction of the relaxation region in which the light confinement in the direction intersecting the traveling direction of the laser light is loose at the end of the semiconductor laser element is replaced with the volume of the gain region or the gain region. The semiconductor laser apparatus according to any one of claims 1 to 4, wherein the plurality of semiconductor laser elements differ from each other in addition to the volume of the above. The semiconductor laser device according to claim 5, wherein the plurality of semiconductor laser elements have a ridge stripe structure and no ridge exists in the relaxation region. The semiconductor laser device according to claim 5, wherein the plurality of semiconductor laser elements have a ridge stripe structure, and the width of the ridge in the relaxation region is wider than that of other portions. The semiconductor laser device according to any one of claims 1 to 7, wherein the plurality of semiconductor laser elements include oscillation wavelengths in wavelength bands of the same color.

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