WO2021166215A1

WO2021166215A1 - Semiconductor laser device

Info

Publication number: WO2021166215A1
Application number: PCT/JP2020/007022
Authority: WO
Inventors: 亮輔宮越; 尚希小坂; 端佳畑
Original assignee: 三菱電機株式会社
Priority date: 2020-02-21
Filing date: 2020-02-21
Publication date: 2021-08-26
Also published as: JPWO2021166215A1; TW202133517A

Abstract

This semiconductor laser device is provided with: a stem (1) having a lead pin (7) inserted so as to be sealed by an insulative member (8) in a through hole that penetrates from the reverse to the obverse of the stem; a heat dissipation block (2) having a lateral surface perpendicular to the obverse of the stem (1); a high-frequency substrate (3) that is fixed to the lateral surface of the heat dissipation block (2) and has mounted thereto a semiconductor laser element (4) having a rear end surface opposing the obverse of the stem (1); a photodiode submount (5) that is disposed on the obverse of the stem (1) and that has fixed thereto a photodiode element (6) for receiving a laser beam emitted from the rear end surface of the semiconductor laser element (4); and a wire (9) that is directed to the lead pin (7) and that is connected to a position deviated in a direction parallel to the lateral surface of the heat dissipation block (2) from a position on the photodiode submount (5) where the photodiode element (6) is disposed.

Description

Semiconductor laser device

This application relates to a semiconductor laser device.

In the semiconductor laser device for communication, a semiconductor laser (LD: Laser Diode) is mounted on a high-frequency substrate in order to wire a signal for high-speed modulation. Some high-frequency boards are fixed to a heat-dissipating block vertically provided on a stem provided with lead pins for electrical wiring from the outside. Further, in order to monitor the output of the LD, a photodiode (PD: Photo Diode) for monitoring that receives the laser beam leaking from the rear end surface of the LD is often provided.

In Patent Document 1, an LD is mounted on the side surface of a metal block on a stem via a high-frequency substrate, a monitor light is emitted from the rear end surface of the LD, and the monitor light is mounted in a groove on the upper surface of the stem. A semiconductor laser device that receives light is disclosed. Further, Patent Document 2 discloses a semiconductor laser device having a configuration in which a PD element is provided in a shallow recess having a sloped bottom surface.

Japanese Unexamined Patent Publication No. 2000-323779 Japanese Unexamined Patent Publication No. 2006-310889

For example, in FIGS. 1 and 3 of Patent Document 1, a bonding wire is directly bonded and wired from the PD element to the lead pin on the side of the PD element away from the high frequency substrate. Further, in FIG. 1 of Patent Document 2, a bonding wire is directly bonded and wired from the center of the PD element to the lead pin in a direction parallel to the high frequency substrate of the PD element. Further, the groove in which the PD element is arranged in Patent Document 1 and the shallow recess in which the PD element is arranged in Patent Document 2 are provided at a position in contact with the surface of the high frequency substrate or away from the surface of the high frequency substrate.

On the other hand, when the PD element is provided on the surface of the stem, it is preferable from the viewpoint of mounting that the PD element is mounted on the PD submount and the lead pin is wired to the PD element via the PD submount. Patent Document 1 and Patent Document 2 do not disclose a PD submount on which a PD element is mounted.

The purpose of this application is to obtain a semiconductor laser device having a small stem and easy mounting of a photodiode element.

The semiconductor laser device disclosed in the present application has a stem having a lead pin inserted so as to be sealed with an insulating member in a through hole penetrating from the back surface to the front surface, and the side surface is perpendicular to the surface of the stem. From the heat radiating block, a high-frequency substrate on which a semiconductor laser element fixed to the side surface of the heat radiating block and having a rear end surface facing the surface of the stem is mounted, and a high-frequency substrate arranged on the surface of the stem, from the rear end surface of the semiconductor laser element. A photodiode submount to which a photodiode element that receives emitted laser light is fixed is provided, and a side surface of the heat dissipation block is provided on the photodiode submount from a position where the photodiode element is arranged. It has a wire to the lead pin connected to a position shifted in a direction parallel to the lead pin.

According to the semiconductor laser device disclosed in the present application, a semiconductor laser device having a small stem and easy mounting of a photodiode element can be obtained.

It is a schematic side sectional view which shows the structure of the semiconductor laser apparatus by Embodiment 1. FIG. It is a schematic top view which shows the structure of the semiconductor laser apparatus by Embodiment 1. FIG. It is a schematic side sectional view for demonstrating the structure of the main part of the semiconductor laser apparatus according to Embodiment 1. FIG. It is the 2nd schematic side sectional view for demonstrating the structure of the main part of the semiconductor laser apparatus by Embodiment 1. FIG. It is a 3rd schematic side sectional view for demonstrating the structure of the main part of the semiconductor laser apparatus according to Embodiment 1. FIG. FIG. 5 is a schematic side sectional view showing another configuration of the semiconductor laser device according to the first embodiment. It is a schematic side sectional view which shows the structure of the semiconductor laser apparatus by Embodiment 2. FIG. It is a schematic top view which shows the structure of the semiconductor laser apparatus by Embodiment 2. FIG. It is a schematic enlarged top view which shows the structure of the photodiode submount of the semiconductor laser apparatus by Embodiment 2. FIG. FIG. 5 is a schematic enlarged top view showing another configuration of the photodiode submount of the semiconductor laser device according to the second embodiment.

The semiconductor laser apparatus according to each embodiment disclosed in the present application will be described with reference to the drawings. The same or corresponding components may be designated by the same reference numerals and the description may be omitted.
Embodiment 1.
FIG. 1 is a side sectional view schematically showing the configuration of the semiconductor laser device according to the first embodiment, and FIG. 2 is a top view. The semiconductor laser device according to the first embodiment includes a stem 1, a heat radiating block 2 on the stem 1 whose side surface is perpendicular to the upper surface of the stem 1, and a high frequency substrate 3 fixed to the side surface of the heat radiating block 2. have. The semiconductor laser element 4 is mounted on the high frequency substrate 3. The photodiode element 6 is mounted via the photodiode submount 5 in the groove 10 formed on the surface of the stem 1 on the side where the heat dissipation block 2 is arranged and whose bottom surface is inclined with respect to the upper surface of the stem 1. ing. Since the electric wiring is introduced from the outside, the stem 1 includes a plurality of

lead pins

7, 11 and 12, which are fixed to a plurality of through holes penetrating the front surface from the back surface via an insulating member 8, respectively. The lead pin 7 is a lead pin for electrically connecting the outside and the wiring pattern provided on the photodiode submount 5, and the lead pin 11 and the lead pin 12 are provided on the high frequency substrate 3 on which the external and the semiconductor laser element 4 are mounted. It is a lead pin for electrically connecting the wiring pattern. In such a semiconductor laser device, low melting point glass is often used as the insulating member 8 from the viewpoint of high frequency loss and sealing property. The semiconductor laser element 4 is mounted so that the front end surface faces the vertical upward direction and the rear end surface faces the upper surface direction of the stem 1 in FIG. 1, and signal light is emitted from the front end surface and coupled to a lens (not shown). .. Further, monitor light is emitted from the rear end surface of the semiconductor laser element 4, received by the photodiode element 6, and output as a monitor current from the photodiode element 6.

Stem 1 is, for example, an SPCC (cold rolled steel plate) disk, and each lead pin is, for example, an alloy of Ni—Fe. The semiconductor laser element 4 and the high-frequency substrate 3, the photodiode element 6, the photodiode submount 5, the lead pin 11, the lead pin 12, and the high-frequency substrate 3 are each fixed by a brazing material such as solder. Further, the terminals connected to the conductor of the high frequency substrate 3, the surface electrode of the semiconductor laser element 4, and the anode electrode of the photodiode element 6 and the lead pin 7 are connected by a wire 9 such as gold. In FIG. 1, the stem 1 and the heat radiating block 2 are made of separate members, but both may be made of the same material, and the stem 1 and the heat radiating block 2 may be integrally formed.

Describe an example of member dimensions. The stem 1 has a circular plate shape with an outer diameter of φ5.6 mm, the through hole is φ0.95 mm, and the lead pin 7 is φ0.43 mm. The semiconductor laser device 4 has a width of 300 μm, a length of 200 μm, and a thickness of 90 μm, and the photodiode element 6 has a width of 400 μm, a length of 400 μm, and a thickness of 150 μm. The high frequency substrate 3 has a width of 2.6 mm, a length of 1.25 mm, and a thickness of 200 μm. The photodiode submount 5 needs to be large enough to be balanced when the photodiode element 6 is mounted, and has a thickness of 0.24 mm.

High-speed operation is required for semiconductor laser devices. The lead pin contains a parasitic inductance, and if the length of the lead pin itself becomes long, it is disadvantageous for high-speed operation. In order to shorten the length of the lead pin, conventionally, the length is shortened so that the upper end of the lead pin does not protrude much from the upper surface of the stem, and instead, the lower end of the high frequency substrate is lowered to near the upper surface of the stem and bonded. .. When the lower end of the high-frequency board is near the upper surface of the stem, the photodiode element and the high-frequency board are separated so that the collet for holding the photodiode element and carrying it to the mounting position does not interfere with the high-frequency board when mounting the photodiode element. I have no choice but to keep a distance. Therefore, the distance between the photodiode element and the semiconductor laser element becomes long, and the monitor light from the rear end surface of the semiconductor laser element at the position of the photodiode element is weak and cannot receive light efficiently. In the semiconductor laser apparatus of the first embodiment, a groove 10 is formed on the surface of the stem 1 up to a portion located under the high-frequency substrate 3, and a photodiode element 6 is fixed to the bottom surface of the groove 10. The sub mount 5 is fixed. As a result, the distance between the photodiode element 6 and the lower end of the high-frequency substrate 3 can be increased, the collet is less likely to interfere with the high-frequency substrate 3, and the photodiode element 6 is mounted closer to the heat dissipation block 2 side than before. be able to. Thereby, for example, the distance from the rear end surface of the semiconductor laser element 4 to the photodiode element 6 can be made closer than before, and the photodiode element 6 can efficiently receive the monitor light from the rear end surface of the semiconductor laser element.

The configuration of the photodiode submount 5 will be described. When the lead pin 7 is arranged away from the photodiode element 6, the outer shape of the stem 1 becomes larger by that amount. In order to reduce the size of the stem 1, the lead pin 7 should be as close to the photodiode element 6 as possible. When the lower end of the high-frequency substrate is close to the upper surface of the stem as in a conventional semiconductor laser device, the space between the surface of the high-frequency substrate and the lead pin 7 facing the surface of the high-frequency substrate is narrow, and the clearance for mounting the photodiode element is small. Becomes smaller. Therefore, it is necessary to reduce the area of the photodiode submount, and it is difficult to mount the wire from the lead pin to the photodiode submount. In the semiconductor laser apparatus according to the first embodiment, the wire 9 for wiring from the lead pin 7 to the photodiode submount 5 is radiated from the position on the photodiode submount 5 where the photodiode element 6 is arranged. It was made to connect at a position shifted in the direction parallel to the side surface of. As a result, the mounting space for the wire can be secured. In this case, the wire 9 for electrical connection to the photodiode element 6 is mounted diagonally, and the wire length may become long. However, the photodiode element 6 is used by applying a direct current. Therefore, the influence of the parasitic inductance contained in the wire 9 can be ignored.

The formation of the groove 10 will be described. When forming the groove 10 on the stem 1, the stem 1 is processed by using a die press. The deeper the groove 10, the greater the distance between the lower end of the high-frequency substrate 3 and the photodiode element 6, and the more interference can be suppressed during mounting. In order to mount the high frequency substrate 3 at a distance of about 0.1 mm from the upper surface of the stem 1, it can be assumed that the mounting variation of the high frequency substrate 3 is about 0.1 mm in the upward direction and about 0.05 mm in the downward direction, and downward. Considering the case of deviation, the depth of the groove 10 should be deep. On the other hand, when the groove 10 is formed close to the lead pin 7, if the groove 10 becomes too deep, the area where the insulating member 8 comes into contact with the stem 1 becomes small, and the airtightness of the stem 1 deteriorates. For example, in the case of the depth of the groove 10 as shown in FIG. 3, the length of contact between the insulating member 8 and the stem is AA'. If the groove 10 is further deepened as shown in FIG. 4, the length becomes BB', the adhesive area between the insulating member 8 and the stem 1 is small, and it becomes difficult to maintain the airtightness of the stem 1. Specifically, for example, assuming that the thickness of the stem 1 shown in FIG. 3 is 1.2 mm, the length of BB'is preferably longer than 0.8 mm. In order to obtain the same groove depth as in FIG. 3, it is conceivable to process as shown in FIG. In FIG. 5, since the length of CC'is the same as that of AA', it is possible to increase the depth of the groove 10 while maintaining the adhesive area between the insulating member 8 and the stem 1. On the other hand, the processing of the groove as shown in FIG. 5 is more difficult than the processing of the groove as shown in FIGS. In this case, the area of the bottom surface of the groove 10 becomes smaller as the groove 10 becomes deeper. Therefore, it is necessary to reduce the area of the photodiode submount 5, and the wire mounting space on the photodiode submount 5 is reduced, which makes mounting difficult. Therefore, in the first embodiment, as described above, the photodiode submount 5 is extended in the direction parallel to the side surface of the heat dissipation block 2 to secure the wire mounting space. Regarding the depth of the groove 10, the total thickness of the photodiode submount 5 and the photodiode element 6 and the depth of the groove 10 do not have to match, and the photodiode element 6 does not have to be completely filled in the groove 10. .. If the thickness of the photodiode submount 5 is 0.24 mm and the thickness of the photodiode element 6 is 0.15 mm, the total thickness is about 0.40 mm. When a groove for filling the photodiode element 6 is formed, a stem is formed. It is difficult to ensure airtightness.

In the semiconductor laser device according to the first embodiment, the groove 10 is formed until it penetrates under the high frequency substrate 3. Therefore, the distance between the photodiode element 6 and the high-frequency substrate 3 in the direction directly above can be increased. Regarding the inclination of the bottom surface of the groove 10, in FIG. 3, the inclination of the photodiode submount on the high frequency substrate 3 side is set to rise, but as shown in FIG. 6, the inclination is such that the high frequency substrate 3 side is lowered, or in any other direction. It may be tilted. The photodiode element 6 may be tilted so that the laser beam radiated from the rear end surface of the semiconductor laser element 4 is not reflected by the photodiode element 6 and returned to the rear end surface of the semiconductor laser element 4 again. That is, the bottom surface of the groove 10 may be inclined in any direction with respect to the surface perpendicular to the optical axis of the laser beam radiated from the rear end surface of the semiconductor laser element 4. In the case of an inclination such that the high-frequency substrate 3 side shown in FIG. 6 is lowered, the distance between the photodiode submount 5 and the lead pin 7 becomes short, so that the wire length can be shortened, which leads to cost reduction. Further, since the lower end of the high frequency substrate 3 and the bottom surface of the groove 10 can be separated from each other, there is an advantage that the mountability is improved. On the other hand, in the structures described in Patent Document 1 and Patent Document 2, since the groove does not penetrate under the high frequency substrate, the distance between the photodiode element 6 and the high frequency substrate 3 in the vertical direction with respect to the upper surface of the stem cannot be separated. , It is difficult to reduce interference during mounting.

Further, by digging the groove 10, the dimensions of the heat dissipation block 2 and the high frequency substrate 3 in the height direction are reduced, and the mounting position of the semiconductor laser element 4 is lowered, so that the amount of light received by the photodiode element 6 can be reduced. Can be increased. In addition, cost reduction is expected due to the reduction of parts. Here, considering the interference when the semiconductor laser element 4 is mounted, it is preferable that the reduction in the dimensions of the heat dissipation block 2 and the high frequency substrate 3 in the height direction is about the same as or less than the depth of the groove 10 formed in the stem 1. For example, when the depth of the groove 10 on the high frequency substrate 3 side is 0.2 mm, it is considered possible to reduce the heights of the heat dissipation block 2 and the high frequency substrate 3 by 0.2 mm as well.

As described above, according to the semiconductor laser apparatus according to the first embodiment, the size of the heat radiating block 2 and the high frequency substrate 3 can be reduced, so that cost reduction can be expected. Further, since the mounting position of the semiconductor laser element 4 can be brought closer to the upper surface of the stem 1, the amount of monitor light received by the photodiode element 6 can be increased.

As described above, in the semiconductor laser device according to the first embodiment, the wire 9 for wiring from the lead pin 7 is placed on the photodiode submount 5 from the position where the photodiode element 6 is arranged. It is connected at a position shifted in the direction parallel to the side surface of the heat dissipation block. Therefore, even if the lead pin 7 and the photodiode element 6 are brought close to each other in order to reduce the size of the stem 1, the wire 9 can be easily mounted from the lead pin 7. Further, since the photodiode submount 5 to which the photodiode element 6 is fixed is arranged on the bottom surface of the groove 10 that penetrates to the bottom of the high frequency substrate 3, the photodiode submount 5 can be easily mounted. Further, since the bottom surface of the groove 10 is inclined with respect to the surface perpendicular to the optical axis of the laser light emitted from the rear end surface of the semiconductor laser element 4, the reflected light from the photodiode element 6 returns to the semiconductor laser element 4. Can be suppressed. Further, since the dimension of the high frequency substrate 3 in the height direction can be reduced by the depth of the groove 10, the area of the high frequency substrate 3 can be reduced and the distance from the semiconductor laser element 4 to the photodiode element 6 can be shortened. The amount of monitor light received by the photodiode element 6 can be increased, and the light receiving efficiency can be increased.

Embodiment 2.
FIG. 7 is a side sectional view schematically showing the configuration of the semiconductor laser device according to the second embodiment, and FIG. 8 is a top view. In the semiconductor laser device according to the second embodiment, as shown in FIG. 7, there is no groove in the portion where the photodiode submount 5 provided in the first embodiment is mounted. Normally, the photodiode submount 5 is mounted in the portion between the lead pin 7 and the heat dissipation block 2, but when the lower end of the high frequency substrate 3 is lowered to near the upper surface of the stem 1, the mounting space of the photodiode submount 5 is large. It becomes smaller. In order to make the size of the stem 1 as small as possible, it is desired that the lead pin 7 and the high frequency substrate 3 be as close as possible. When the distance between the lead pin 7 and the high-frequency substrate 3 is set to be about the same as the dimension of the photodiode element 6, the space for connecting the wire 9 to the photodiode submount 5 becomes small, which makes wire mounting difficult. Even when the photodiode submount 5 is arranged on the upper surface of the stem 1 in which the groove is not formed as shown in FIG. 8, the position where the wire 9 from the lead pin 7 is connected is the same as that described in the first embodiment. Is set to a position deviated from the position where the photodiode element 6 is arranged in a direction parallel to the side surface of the heat dissipation block 2, so that wire mounting becomes easy.

FIG. 9 is a schematic top view showing an enlarged portion of the photodiode submount 5 and the lead pin 7 which are the main parts of the semiconductor laser device according to the second embodiment. FIG. 10 is a schematic top view showing a photodiode submount 5 having a configuration different from that of FIG. The photodiode submount 5 shown in FIG. 10 is changed in shape from, for example, a square having a size of 0.7 mm × 0.7 mm shown in FIG. 9 to a thin rectangle having a size of 0.2 mm × 0.5 mm. By reducing the area of the photodiode submount 5 to about 1/5 in this way, it is expected that the cost of the member will be reduced. The smaller the photodiode submount 5, the better, as long as the shape satisfies the balance when the photodiode element 6 is mounted and the wire mounting portion can be secured. Regarding the wire mounting to the photodiode submount 5, it is considered that the wire can be mounted if there is a space of 0.1 × 0.1 mm, but in the second embodiment, the photodiode element 6 is mounted on the photodiode submount 5. It is desirable that the sub-mount protrudes by 0.3 mm or more from the side end face of the photodiode element 6 in consideration of the step difference due to riding. Needless to say, the photodiode submount 5 having the shape shown in FIG. 10 can also be applied to the semiconductor laser device according to the first embodiment in which the groove 10 is provided.

Although various exemplary embodiments and examples are described in the present application, the various features, embodiments, and functions described in one or more embodiments are of particular embodiments. It is not limited to application, but can be applied to embodiments alone or in various combinations. Therefore, innumerable variations not illustrated are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 stem, 2 heat dissipation block, 3 high frequency substrate, 4 semiconductor laser element, 5 photodiode submount, 6 photodiode element, 7 lead pin, 8 insulation member, 9 wire, 10 groove

Claims

A stem having a lead pin inserted so as to be sealed with an insulating member in a through hole penetrating from the back surface to the front surface.
A heat dissipation block whose sides are perpendicular to the surface of the stem,
A high-frequency substrate fixed to the side surface of the heat dissipation block and mounted with a semiconductor laser element whose rear end surface faces the surface of the stem.
A photodiode submount arranged on the surface of the stem and fixed with a photodiode element that receives laser light radiated from the rear end surface of the semiconductor laser element.
With
A semiconductor laser diode device having a wire to a lead pin connected to a position on the photodiode submount that is displaced in a direction parallel to the side surface of the heat dissipation block from a position where the photodiode element is arranged.
The semiconductor laser device according to claim 1, wherein the photodiode submount is fixed to the bottom surface of a groove formed on the surface of the stem.
The semiconductor laser device according to claim 2, wherein the groove penetrates under the high-frequency substrate.
The semiconductor laser device according to claim 2 or 3, wherein the bottom surface of the groove is inclined with respect to a surface perpendicular to the optical axis of the laser beam radiated from the rear end surface of the semiconductor laser element.