Semiconductor laser device

Abstract

A semiconductor laser device according to the present disclosure comprises: a stem; a thermoelectric element that is provided to a position which is on an upper surface of the stem and which is displaced to one side with respect to the center of the stem; a semiconductor laser that is subject to temperature control by the thermoelectric element; a heat dissipation block that has a first portion which is provided on said one side on the opposite side from the upper surface of the stem, at least part of which is provided to a rear surface of the stem on the opposite side from the upper surface, a second portion which is provided to the rear surface of the stem, and which extends from the first portion to directly below the thermoelectric element, and a third portion which is provided on said one side on a side surface of the stem; and a plurality of lead pins that pass through the stem from the upper surface to the rear surface and that are provided around the second portion.

Description

[Technical field]

[0001] The present disclosure relates to a semiconductor laser device. [Background technology]

[0002] Patent Document 1 discloses a CAN package type optical module including a stem having a first surface to be connected to a flexible substrate and a second surface opposite to the first surface. A signal pin penetrates the stem from the first surface to the second surface and protrudes from the first surface. An insulating material is filled between the stem and the signal pin. An optical semiconductor is connected to the signal pin on the second surface side of the stem. A ground pin is provided on the first surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6825756 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, in a semiconductor laser device such as that of Patent Document 1, the characteristics of the semiconductor laser change depending on the temperature. In order to keep the characteristics of the semiconductor laser stable even when the environmental temperature changes, a thermoelectric element is generally built into the semiconductor laser device and is controlled so that the temperature of the semiconductor laser is constant. The thermoelectric element needs to exhaust heat not only from the heat of the semiconductor laser, the heat that flows in from the outside via the lead pins and wires, but also from the heat generated by the thermoelectric element itself.

[0005] Even in semiconductor laser devices with built-in thermoelectric elements, a CAN package using a stem may be used to reduce costs. However, heat dissipation from the stem is generally difficult due to its shape. In addition, if the heat generated by the semiconductor laser increases in response to the demand for higher optical output from the semiconductor laser, it is expected that it will become even more difficult to keep the temperature of the semiconductor laser constant over a wide temperature range.

[0006] An object of the present disclosure is to provide a semiconductor laser device that can obtain good heat dissipation characteristics. [Means for solving the problem]

[0007] The semiconductor laser device according to the present disclosure comprises a stem, a thermoelectric element provided on an upper surface of the stem at a position shifted to one side relative to a center of the stem, a semiconductor laser whose temperature is controlled by the thermoelectric element, a heat dissipation block having a first portion provided on the one side opposite the top surface of the stem and at least a portion of the first portion provided on the back surface of the stem opposite the top surface, a second portion provided on the back surface of the stem and extending from the first portion to just below the thermoelectric element, and a third portion provided on the one side of the stem, and a plurality of lead pins penetrating the stem from the top surface to the back surface and provided around the second portion. Effect of the Invention

[0008] In the semiconductor laser device according to the present disclosure, the heat dissipation path from the thermoelectric element to the side surface of the stem can be shortened, and a large contact area between the stem and the heat dissipation block can be secured, thereby obtaining good heat dissipation characteristics. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view of a semiconductor laser device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of a semiconductor laser device according to a first embodiment. [Diagram 3]1 is a bottom view of a semiconductor laser device according to a first embodiment. [Figure 4] FIG. 1 is a side view of a semiconductor laser device according to a comparative example. [Diagram 5] FIG. 1 is a cross-sectional view of a semiconductor laser device according to a comparative example. [Figure 6] FIG. 4 is a bottom view of a semiconductor laser device according to a comparative example. [Figure 7] FIG. 11 is a cross-sectional view of a semiconductor laser device according to a second embodiment. [Figure 8] FIG. 11 is a bottom view of a semiconductor laser device according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a semiconductor laser device according to a modification of the second embodiment. [Figure 10] FIG. 11 is a cross-sectional view of a semiconductor laser device according to a third embodiment. [Figure 11] FIG. 11 is a bottom view of a semiconductor laser device according to a third embodiment. [Figure 12] FIG. 11 is a cross-sectional view of a semiconductor laser device according to a fourth embodiment. [Figure 13] FIG. 11 is a bottom view of a semiconductor laser device according to a fourth embodiment. [Figure 14] FIG. 13 is a side view of a semiconductor laser device according to a fifth embodiment. [Figure 15] FIG. 11 is a cross-sectional view of a semiconductor laser device according to a fifth embodiment. [Figure 16] FIG. 13 is a bottom view of a semiconductor laser device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A semiconductor laser device according to each embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0011] Embodiment 1 FIG. 1 is a side view of a semiconductor laser device 100 according to the first embodiment. FIG. 2 is a cross-sectional view of the semiconductor laser device 100 according to the first embodiment. FIG. 3 is a bottom view of the semiconductor laser device 100 according to the first embodiment. The semiconductor laser device 100 is configured in a CAN package. In the semiconductor laser device 100, a thermoelectric element 12 is mounted on the upper surface of a stem 10. A carrier 14 on which a semiconductor laser 16 is mounted, and a thermistor 18 are mounted on the upper surface of the thermoelectric element 12.

[0012] The semiconductor laser 16 converts an electric signal into an optical signal. The temperature of the semiconductor laser 16 is controlled by the thermoelectric element 12. Specifically, the thermoelectric element 12 is provided to heat or cool the semiconductor laser 16 and keep the temperature of the semiconductor laser 16 constant. The thermistor 18 is mounted near the semiconductor laser 16 and changes its resistance value depending on the temperature.

[0013] A number of lead pins 40 penetrate the stem 10 from the top surface to the back surface opposite the top surface. The lead pins 40 are provided to supply power to the semiconductor laser 16 or the thermoelectric element 12. An insulator 42 such as glass is filled between the lead pins 40 and the stem 10. The stem 10 and the number of lead pins 40 are separated by the insulator 42 and are not electrically connected. The ground pin 41 is electrically connected to the stem 10.

[0014] The flexible substrate 44 is connected to the lead pins 40 and the ground pin 41. A wiring pattern for electrically connecting to an optical transceiver is formed on the flexible substrate 44. A heat dissipation block 30 for dissipating heat from the thermoelectric element 12 is provided on the side and bottom of the stem 10. On the upper surface side of the stem 10, the semiconductor laser 16 is covered with a cap 20. The cap 20 has an extraction window for an optical signal such as a lens, and hermetically seals the semiconductor laser 16. In the following bottom views, the flexible substrate 44 may be omitted in order to explain the shape of the heat dissipation block 30 on the back surface side of the stem 10.

[0015] The thermoelectric element 12 is provided on the upper surface of the stem 10 at a position offset to one side with respect to the center of the stem 10. The one side is the side indicated by arrow A in Figures 2 and 3. The heat dissipation block 30 has a first portion 31, a second portion 32 and a third portion 33. The first portion 31 is provided on the one side indicated by arrow A on the back surface side of the stem 10. At least a part of the first portion 31 is provided on the back surface of the stem 10. The second portion 32 is provided on the back surface of the stem 10 and extends from the first portion 31 to directly below the thermoelectric element 12. The first portion 31 is a portion extending in the Y direction in Figure 3, and the second portion 32 is a portion extending in the X direction in Fig. 3. The heat dissipation block 30 is T-shaped on the back surface of the stem 10. The third portion 33 is provided on one side of the side surface of the stem 10 indicated by arrow A. As shown in Fig. 2, the heat dissipation block 30 is L-shaped in cross section.

[0016] The multiple lead pins 40 are arranged around the second portion 32 in a plan view. The multiple lead pins 40 are arranged, for example, on a circumference in a plan view. The multiple lead pins 40 may be arranged in an arc shape. The second portion 32 is arranged so as to enter an area surrounded by the multiple lead pins 40. The first portion 31 is arranged outside the multiple lead pins 40. The thermoelectric element 12 is mounted offset from the center of the stem 10 in a direction where the lead pins 40 are not arranged, that is, in the direction where the circle formed by the multiple lead pins 40 opens out.

[0017] Next, the operation of the semiconductor laser device 100 will be described. The semiconductor laser 16 converts an electrical signal input from an optical transceiver via the flexible substrate 44 and the lead pins 40 into an optical signal. The semiconductor laser 16 transmits the converted optical signal from the window of the cap 20. The characteristics of the semiconductor laser 16, such as optical output and wavelength, change depending on the temperature. For this reason, depending on the modulation method of the optical signal, there is a risk of significant deterioration in signal quality. The thermoelectric element 12 heats or cools so that the resistance value of the thermistor 18, that is, the detected temperature, becomes constant. This makes it possible to keep the temperature of the semiconductor laser 16 constant, and control the semiconductor laser 16 so that its characteristics do not change even if the environmental temperature changes.

[0018] FIG. 4 is a side view of a semiconductor laser device 800 according to a comparative example. FIG. 5 is a cross-sectional view of the semiconductor laser device 800 according to the comparative example. FIG. 6 is a bottom view of the semiconductor laser device 800 according to the comparative example. In the comparative example, a plurality of lead pins 40 are arranged in a circular shape in a plan view. The thermoelectric element 12 is mounted at the center of the stem 810. The heat dissipation block 830 is in thermal contact with the side of the stem 810, but is not in contact with the back surface. The surface of the heat dissipation block 830 opposite to the surface in contact with the stem 810 is a heat dissipation surface that is in thermal contact with a heat sink of an optical transceiver and dissipates heat generated in the semiconductor laser device 800.

[0019] The heat discharged from the thermoelectric element 12 mainly includes heat generated by the semiconductor laser 16, heat flowing in through the lead pins and the like by thermal conduction, and heat generated by the thermoelectric element 12 itself. The heat dissipation path from the thermoelectric element 12 is a path from the side of the stem 810 to the heat dissipation block 830 via the thermoelectric element 12 and the stem 810 as shown by the arrow 83. In the semiconductor laser device 800 according to the comparative example, there is only one heat dissipation path as shown by the arrow 83. In addition, since the thermoelectric element 12 is mounted in the center of the stem 810, the heat dissipation path from the thermoelectric element 12 to the side of the stem 810 is long. Furthermore, a glass insulator 42 with extremely low thermal conductivity is present in the middle of the heat dissipation path. For this reason, the heat dissipation path becomes narrow, and there is a risk that the heat cannot be discharged efficiently.

[0020] In contrast, in this embodiment, the heat dissipation block 30 is in thermal contact with the back surface and side surface of the stem 10. Therefore, a large contact area between the stem 10 and the heat dissipation block 30 can be secured. Therefore, the thermal resistance can be reduced and the heat can be dissipated efficiently. In addition, the first portion 31 and the second portion 32 of the heat dissipation block 30 are in contact with the back surface of the stem 10. Therefore, a larger contact area between the stem 10 and the heat dissipation block 30 can be secured. In addition, in this embodiment, the surface of the third portion 33 of the heat dissipation block 30 opposite to the stem 10 becomes a heat dissipation surface that thermally contacts the heat sink of the optical transceiver. As shown by the arrow 81, there is a heat dissipation path from the side surface of the stem 10 to the heat dissipation block 30 via the thermoelectric element 12 and the stem 10. Furthermore, as shown by the arrow 82, there is a path from the back surface of the stem 10 to the heat dissipation block 30 via the thermoelectric element 12 and the stem 10. In this way, in this embodiment, two types of heat dissipation paths can be secured.

[0021] In addition, the thermoelectric element 12 is provided at a position shifted toward the third portion 33 of the heat dissipation block 30 from the center of the stem 10. This makes it possible to shorten the heat dissipation path from the thermoelectric element 12 to the side surface of the stem 10. Furthermore, the multiple lead pins 40 are of The insulator 42 is provided so as to avoid a position that overlaps with the heat dissipation block 30 in a plan view. In other words, the insulator 42 is not provided in the position of the stem 10 that overlaps with the heat dissipation block 30 in a plan view. Therefore, there is no glass insulator 42 with extremely low thermal conductivity in the middle of the heat dissipation path, and heat can be dissipated efficiently. Furthermore, since the rear surface shape of the heat dissipation block 30 is T-shaped, the second portion 32 can cover the part of the rear surface of the stem 10 directly below the thermoelectric element 12. Therefore, heat can be efficiently transferred from directly below the thermoelectric element 12 to the heat dissipation surface. From the above, good heat dissipation characteristics can be obtained in this embodiment.

[0022] Furthermore, since the cross-sectional shape of the heat dissipation block 30 is L-shaped, it is possible to easily attach the heat dissipation block 30 to the stem 10. The heat dissipation block 30 of this embodiment is capable of contacting the side and back surface of the stem 10 with a single member.

[0023] A gel or adhesive with excellent thermal conductivity may be filled between the heat dissipation block 30 and the side and back surface of the stem 10 to improve thermal contact. Also, in Fig. 1, the heat dissipation block 30 extends up to near the upper surface of the cap 20. This allows the slight heat dissipation from the cap 20 to be transmitted to the heat dissipation block 30, and ensures the stability of the attachment of the semiconductor laser device 100 to the optical transceiver.

[0024] As a modification of this embodiment, the multiple lead pins 40 do not have to be arranged circumferentially. The multiple lead pins 40 only need to be arranged so as not to overlap with the heat dissipation block 30. Furthermore, the number of multiple lead pins 40 is not limited. Furthermore, the structure of the heat dissipation block 30 is not limited to that shown in FIGS. 1 to 3. The heat dissipation block 30 does not have to be T-shaped on the back surface of the stem 10. Furthermore, depending on the required heat dissipation characteristics, the second portion 32 does not have to extend to directly below the thermoelectric element 12.

[0025] The above-mentioned modifications can be appropriately applied to the semiconductor laser devices according to the following embodiments. Note that the semiconductor laser devices according to the following embodiments have many points in common with the first embodiment, so the following description will focus on the differences from the first embodiment.

[0026] Embodiment 2 Fig. 7 is a cross-sectional view of a semiconductor laser device 200 according to the second embodiment. Fig. 8 is a bottom view of the semiconductor laser device 200 according to the second embodiment. In this embodiment, the structures of a stem 210 and a heat dissipation block 230 are different from those of the stem 10 and the heat dissipation block 30 of the first embodiment. The other configurations are the same as those of the first embodiment. The portion of the stem 210 where the back surface contacts the heat dissipation block 230 is thinner than the other portions of the stem 210.

[0027] The heat dissipation block 230 has a first portion 231, a second portion 232, and a third portion 233, similar to the first embodiment. The heat dissipation block 230 has a higher thermal conductivity than the stem 210. The material of the stem 210 is, for example, iron with a thermal conductivity of 80 W / m / K. In this case, the material of the heat dissipation block 230 can be, for example, copper with a thermal conductivity of 398 W / m / K or aluminum with a thermal conductivity of 237 W / m / K.

[0028] By using a material having a higher thermal conductivity than the stem 210 for the heat dissipation block 230 and thinning the stem 210, heat can be efficiently dissipated from the rear surface of the stem 210. In addition, the protrusion of the heat dissipation block 230 from the rear surface of the stem 210 can be reduced. This allows the flexible substrate 44 to be connected to the bases of the lead pins 40 and the ground pin 41. Therefore, the modulation characteristics of the semiconductor laser device 200 can be made faster.

[0029] FIG. 9 is a cross-sectional view of a semiconductor laser device 300 according to a modification of the second embodiment. The semiconductor laser device 300 includes a stem 310 and a heat dissipation block 330. The heat dissipation block 330 has a first portion 331, a second portion 332, and a third portion 333, similar to the first embodiment. In the modification, at least a part of the portion of the stem 310 where the back surface is in contact with the heat dissipation block 330 is thinner than other portions of the stem 310. In the example of FIG. 9, only the portion of the stem 310 directly below the thermoelectric element 12 is formed thin. In this case, the same effect as the second embodiment can be obtained.

[0030] Embodiment 3 FIG. 10 is a cross-sectional view of a semiconductor laser device 400 according to the third embodiment. FIG. 11 is a bottom view of the semiconductor laser device 400 according to the third embodiment. The semiconductor laser device 400 includes a stem 410 and a heat dissipation block 430. The heat dissipation block 430 has a first portion 431, a second portion 432, and a third portion 433, as in the first embodiment. This embodiment differs from the first embodiment in that the ground pin 41 is not provided. In addition, the stem 410, the heat dissipation block 430, and the joining member joining the stem 410 and the heat dissipation block 430 have electrical conductivity. The joining member fills the gap between the side and back surface of the heat dissipation block 430 and the stem 410. For good thermal contact and electrical contact, the joining member is preferably a gel or adhesive having thermal conductivity and electrical conductivity.

[0031] The stem 410 of this embodiment does not have a ground pin. However, since the heat dissipation block 430, the stem 410, and the joining member have electrical conductivity, the ground can be taken by the heat dissipation block 430. In other words, the heat dissipation block 430 is a ground terminal for the semiconductor laser 16. Also, since the stem 410 does not have the ground pin 41, the width of the portion where the lead pins 40 are not arranged can be made wider compared to the first embodiment. Therefore, the contact area between the back surface of the stem 410 and the heat dissipation block 430 can be made larger, and heat can be dissipated more efficiently.

[0032] Embodiment 4 Fig. 12 is a cross-sectional view of a semiconductor laser device 500 according to the fourth embodiment. Fig. 13 is a bottom view of the semiconductor laser device 500 according to the fourth embodiment. The semiconductor laser device 500 includes a stem 510 and a heat dissipation block 530. The heat dissipation block 530 has a first portion 531, a second portion 532, and a third portion 533, similar to the first embodiment. A recess 510a is formed on the rear surface of the stem 510 directly below the thermoelectric element 12. A ground pin 541 is inserted into the recess 510a.

[0033] Ground pin 541 is attached to recess 510a of stem 510 in a state in which it is electrically connected to stem 510 by means of welding, brazing, soldering, or the like. Ground pin 541 has a higher thermal conductivity than stem 510. Stem 510 is made of a material such as iron with a thermal conductivity of 80 W / m / K. In this case, ground pin 541 is made of a material such as copper with a thermal conductivity of 398 W / m / K or aluminum with a thermal conductivity of 237 W / m / K.

[0034] The ground pin 541 passes through the heat dissipation block 530. A hole is formed in the heat dissipation block 530 to pass the ground pin 541 through. To ensure thermal contact, a gel or adhesive with excellent thermal conductivity is filled between the ground pin 541 and the heat dissipation block 530.

[0035] In this embodiment, the heat from the thermoelectric element 12 can be dissipated to the heat dissipation block 530 via the ground pin 541. Therefore, the heat can be efficiently dissipated from the back surface of the stem 510. 3 Similarly, it is possible to increase the width of the portion where the lead pins 40 are not arranged. This makes it possible to increase the contact area between the rear surface of the stem 510 and the heat dissipation block 530, thereby enabling more efficient heat dissipation.

[0036] Embodiment 5. FIG. 14 is a side view of a semiconductor laser device 600 according to the fifth embodiment. FIG. 15 is a cross-sectional view of the semiconductor laser device 600 according to the fifth embodiment. FIG. 16 is a bottom view of the semiconductor laser device 600 according to the fifth embodiment. The semiconductor laser device 600 includes a stem 610 and a heat dissipation block 630. The heat dissipation block 630 includes a first portion 631, a second portion 632, and a third portion 633, similar to the first embodiment. A notch 610b is formed in the side surface of the stem 610. The heat dissipation block 630 includes a protrusion 630a in the third portion 633. The protrusion 630a and the notch 610b fit together.

[0037] The heat dissipation block in the first to fourth embodiments can rotate freely around the central axis of the stem. This can lead to the possibility of the heat dissipation surface being misaligned. In the present embodiment, the notch 610b of the stem 610 and the protrusion of the heat dissipation block 630 fit together, so that the rotation of the heat dissipation block 630 can be prevented. In addition, the heat dissipation surface can be easily oriented in the direction as designed, and the positioning and attachment of the heat dissipation block 630 can be easily performed. In addition, the heat dissipation block 630 may be formed of a material having a higher thermal conductivity than the stem 610. This allows the heat to be efficiently dissipated at the notch 610b of the stem 610.

[0038] The technical features described in each embodiment may be used in appropriate combination. [Explanation of symbols]

[0039] 10 stem, 12 thermoelectric element, 14 carrier, 16 semiconductor laser, 18 thermistor, 20 cap, 30 heat dissipation block, 31 first part, 32 second part, 33 third part, 40 lead pin, 41 ground pin, 42 insulator, 44 flexible substrate, 100, 200 semiconductor laser device, 210 stem, 230 heat dissipation block, 231 first part, 232 second part, 233 third part, 300 semiconductor laser device, 310 stem, 330 heat dissipation block, 331 first part, 332 second part, 333 third part, 400 semiconductor laser device, 410 stem, 430 heat dissipation block, 431 first part, 432 second part, 433 third part, 500 semiconductor laser device, 510 stem, 510a Recess, 530, heat dissipation block, 531, first portion, 532, second portion, 533, third portion, 541, ground pin, 600, semiconductor laser device, 610, stem, 610b, notch, 630, heat dissipation block, 630a, protrusion, 631, first portion, 632, second portion, 633, third portion, 800, semiconductor laser device, 810, stem, 830, heat dissipation block

Claims

1. Stem and a thermoelectric element provided on an upper surface of the stem at a position shifted to one side with respect to a center of the stem; a semiconductor laser whose temperature is controlled by the thermoelectric element; a heat dissipation block having: a first portion provided on the one side of the stem opposite to the top surface, with at least a portion provided on a back surface of the stem opposite to the top surface; a second portion provided on the back surface of the stem, extending from the first portion to immediately below the thermoelectric element; and a third portion provided on the one side of the stem; a plurality of lead pins penetrating the stem from the top surface to the back surface and provided around the second portion; A semiconductor laser device comprising:

2. the stem and the plurality of lead pins are separated by an insulator; 2. The semiconductor laser device according to claim 1, wherein the plurality of lead pins are provided on the stem so as to avoid positions that overlap the heat dissipation block in a plan view.

3. 3. The semiconductor laser device according to claim 1, wherein the plurality of lead pins are arranged circumferentially in a plan view.

4. the heat dissipation block has a higher thermal conductivity than the stem; 3. The semiconductor laser device according to claim 1, wherein at least a portion of the stem, where the back surface of the stem is in contact with the heat dissipation block, is thinner than other portions of the stem.

5. the stem, the heat dissipation block, and a member joining the stem and the heat dissipation block are electrically conductive; 3. The semiconductor laser device according to claim 1, wherein the heat dissipation block is a ground terminal for the semiconductor laser.

6. 3. The semiconductor laser device according to claim 1, further comprising a ground pin that is inserted into a recess formed in a portion of the back surface of the stem directly below the thermoelectric element, penetrates the heat dissipation block, and has a thermal conductivity higher than that of the stem.

7. 3. The semiconductor laser device according to claim 1, wherein a notch is formed in the side surface of the stem, and the third portion and the notch are fitted together.

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