JP2001044554A - Ld stem and optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an LD stem and an optical pickup having high thermal insulation effect which can use even a blue LD having a conspicuously greater heat generation amount than that of a red LD by a method, wherein a heat pipe is airtightly inserted into a through-hole provided in an eyelet and a support member. SOLUTION: In this LD stem, there is provided, in a slab-like eyelet 1 made of soft iron, a laser support member 2 made of copper for supporting a semiconductor laser (LD) 4, an OPIC support member 8 for supporting an OPIC 5 in which PD is integrated with an I-V amplifier, and an airtight terminal 6 which is airtightly sealed by a glass sealing part 7. In the meantime, in the LD system in which there are provided in the slab-like eyelet 1 the support member 2 for supporting the semiconductor laser 4 and the airtight terminal 6 which is made airtight by glass sealing processing, a through-hole 9 substantially in parallel to the airtight terminal 6 is provided in the eyelet 1 and the support member 2, and the heat pipe 3 is inserted airtightly into the through-hole 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an LD stem on which a semiconductor laser is mounted and an optical pickup.

[0002]

2. Description of the Related Art Conventionally, a semiconductor laser (LD) used for an optical pickup such as a CD or DVD has a size of several hundred μm.
Although it is as small as an angle, it generates a large amount of heat per volume, so that the temperature of the light emitting portion easily rises unless it is cooled effectively. In addition, the semiconductor laser causes deterioration in characteristics such as an increase in oscillation threshold, a change in oscillation wavelength, and a shortened life due to self-heating. Therefore, the semiconductor laser is cooled by mounting the semiconductor laser on the LD stem using a supporting member having high thermal conductivity for supporting the semiconductor laser.

FIG. 5 is a view showing a conventional LD stem. In this LD stem, a copper support member 23 for supporting a semiconductor laser 22 and a terminal 24 having a glass sealing process are provided.
a and 24b are provided on an iron plate-like eyelet 25 made of iron.

[0004]

However, in the LD stem of FIG. 5, the support member 23 on which the semiconductor laser 22 is mounted is made of copper and has a high thermal conductivity of about 400 W / m * k, but the eyelet 25 is made of soft iron. Thermal conductivity of 50
As low as about W / m * k, the heat radiation characteristics of the entire LD stem are not very high. In this case, the eyelet 25 is formed using copper having good thermal conductivity,
Although it is conceivable that the support member 5 and the support member 23 are integrally formed, copper cannot be subjected to glass sealing, and in this case, it is difficult to form the hermetic terminals 24a and 24b.

On the other hand, Japanese Patent Application Laid-Open No. Hei 8-242041 discloses a structure in which thermal conductivity is improved as compared with a conventional LD stem. FIG. 6 is a view showing an LD stem disclosed in Japanese Patent Application Laid-Open No. H8-242041, and in the LD stem of FIG. 6, a through hole 39 is provided in an eyelet 37 made of soft iron.
A copper support member 33 having good thermal conductivity is attached to an eyelet 37.
Is inserted into the through hole 39. As a result, heat from the semiconductor laser 32 is transmitted to the eyelet 3 via the support member 33.
7 is dissipated to the bottom surface of the LD 7 and the heat radiation characteristics can be improved as compared with the conventional LD stem.

However, in a blue LD required for a next-generation DVD-RAM pickup, a sufficient cooling effect cannot be obtained even with the above-described heat radiation structure. That is, since the heat generation of the blue LD is more than twice that of the red LD used in the current generation DVD-RAM pickup, the temperature rise of the blue LD can be suppressed by increasing the thermal conductivity to some extent. Can not.

In recent years, an OPIC-integrated LD stem using a hologram has been widely used, and the number of terminals of the LD stem is ten or more. The thermal conductivity of the glass sealing portion for fixing this terminal is about 0.6 W / m * k, which is much lower than that of the eyelet, and therefore the effective thermal conductivity of the LD stem. Is further reduced. As described above, the conventional LD stem has a problem in that it is not possible to effectively radiate heat to the blue LD, which generates much more heat than the red LD.

An object of the present invention is to provide an LD stem and an optical pickup having a high heat radiation effect that can be used even in a blue LD having a much larger heat generation than a red LD.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a support member for supporting a semiconductor laser and an airtight terminal are provided on an eyelet.
In the D stem, a through hole is provided in an eyelet and a support member, and a heat pipe is inserted into the through hole in an airtight manner.

According to a second aspect of the present invention, in the LD stem according to the first aspect, a center axis of the heat pipe is shifted from a center axis of the eyelet.

According to a third aspect of the present invention, in the LD stem of the first aspect, the heat pipe is disposed inside a hermetic terminal.

According to a fourth aspect of the present invention, in the LD stem of the first aspect, the LD stem and the heat pipe are meshed in a conical shape.

According to a fifth aspect of the present invention, in the LD stem of the first aspect, a semiconductor laser is directly mounted on the heat pipe.

According to a sixth aspect of the present invention, in the LD stem of the first aspect, a mounting board for mounting the LD stem is further provided.
It is characterized in that a hole through which the heat pipe penetrates is formed.

According to a seventh aspect of the present invention, there is provided an optical pickup using the LD stem according to any one of the first to sixth aspects.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 (a) and 1 (b) show L according to the present invention.
FIG. 3 is a diagram illustrating a first configuration example of a D stem. FIG.
1A is a plan view, and FIG. 1B is a cross-sectional view taken along line AA ′ of FIG. 1A. Referring to FIG. 1, the LD stem includes a copper laser support member 2 for supporting a semiconductor laser (LD) 4 on a flat-shaped eyelet 1 made of soft iron.
An OPIC support member 8 for supporting an OPIC 5 in which a PD and an IV amplifier are integrated, and a hermetic terminal 6 hermetically sealed by a glass sealing portion 7 are provided.

According to the present invention, in the LD stem in which the support member 2 for supporting the semiconductor laser 4 and the hermetic terminal 6 hermetically sealed by glass sealing are provided on the flat eyelet 1, the hermetic terminal is provided. A through hole 9 substantially parallel to 6 is provided in the eyelet 1 and the support member 2,
The heat pipe 3 is hermetically inserted into the through hole 9.

That is, the easiest way to increase the thermal conductivity of the LD stem is to use a material having a high thermal conductivity. However, silver or diamond can be considered as a material having a higher thermal conductivity than copper. However, if these are used for the LD stem, they become extremely expensive. On the other hand, the heat pipe has an effective thermal conductivity that is at least one order of magnitude higher than that of copper. However, the structure of the conventional LD stem cannot sufficiently bring out the performance of the heat pipe. This is because the LD stem and the heat pipe have conventionally been treated as independent parts, and therefore little consideration has been given to the LD stem for extracting the capability of the heat pipe.

Therefore, in the present invention, a through hole 9 substantially parallel to the airtight terminal 6 is provided in the eyelet 1 and the support member 2, and the heat pipe 3 is inserted into the through hole 9 in an airtight manner, so that a heat source is provided. Thus, the LD stem and the evaporating section of the heat pipe 3 can be brought close to each other, so that the heat conducting ability of the heat pipe 3 can be sufficiently extracted.

Here, the heat pipe 3 is in the form of a copper pipe and has a small amount of hydraulic fluid inside.
(Water or alcohol) is sealed in a vacuum. The operating principle of the heat pipe 3 is as follows. That is, a groove or a net called a wick is provided on the inner wall of the heat pipe 3, and the working fluid spreads over the entire inner wall by a capillary phenomenon. When a part of the heat pipe 3 is heated, the working fluid evaporates at that part, the steam moves in a vacuum, and agglomerates in a low temperature part. Since the working fluid is replenished one after another due to the capillary phenomenon, heat transfer is continuously performed. Conventionally, as the heat pipe 3, only a relatively large one could be made, so that its application range was limited.
m, and a heat pipe having a thickness of 1 mm has also been developed. Therefore, a small heat pipe can be used as the heat pipe 3 used in the present invention.

In the examples of FIGS. 1A and 1B, the LD stem is configured as an OPIC-integrated LD stem using a hologram.
Considering the ease of mounting the (PIC) 5, the semiconductor laser 4
Are mounted near the center axis of the eyelet 1. Therefore,
1A and 1B, the center axis of the heat pipe 3 is shifted from the center axis of the eyelet 1. As a result, the heat pipe 3 does not spatially overlap with the semiconductor laser 4 on the center axis of the eyelet 1, so that the evaporating portion of the heat pipe 3 can be brought close to the vicinity of the semiconductor laser 4, and the semiconductor laser 4 It can be cooled effectively. That is, in the configuration examples of FIGS. 1A and 1B,
Since the semiconductor laser 4 and the heat pipe 3 are very close to each other, the semiconductor laser 4 can be cooled effectively.

As described above, the number of the terminals 6 of the OPIC-integrated LD stem using the hologram is 10 or more, and the thermal conductivity of the glass sealing portion 7 for fixing the terminals 6 is made. Is about 0.6 W / m * k, which is much lower in thermal conductivity than the eyelet 1, and therefore, the thermal resistance between the inside and the outside of the terminal 6 of the LD stem is large. Therefore, in order to effectively cool the semiconductor laser (LD) 4 mounted inside the terminal 6, the heat pipe 3 may be mounted on the same side as the semiconductor laser 4. 1A and 1B, the heat pipe 3 is disposed inside the terminal 6, whereby the semiconductor laser 4 is effectively disposed without passing through the terminal 6 having a large thermal resistance. Can be cooled.

FIGS. 2A and 2B show LDs according to the present invention.
It is a figure showing the 2nd example of composition of a stem. FIG. 2 (a)
FIG. 2B is a plan view, FIG. 2B is a cross-sectional view taken along line BB ′ of FIG. 2A, and FIG. 2A and FIG.
Parts corresponding to (a) and (b) are denoted by the same reference numerals.

In the configuration examples of FIGS. 2A and 2B, FIG.
The heat pipe 3 has the same configuration as the basic structure of the LD stem shown in FIG. 3B, but has a conical shape at the end sealing portion due to a process during processing. 3 has a conical shape. That is, when the size of the support member 2 that supports the semiconductor laser 4 is not large enough to completely penetrate the heat pipe 3, the engagement between the LD stem and the heat pipe 3 is made conical, so that the heat pipe 3 can be as close as possible to the semiconductor laser 4. As described above, since the engagement between the LD stem and the heat pipe 3 is conical, even when the size of the support member 2 that supports the semiconductor laser 4 is not large enough to completely penetrate the heat pipe 3. Thus, the heat pipe 3 can be brought close to the semiconductor laser 4. That is, even when the support member 2 of the semiconductor laser 4 is small and the through-hole of the heat pipe 3 cannot be provided, the heat pipe 3 and the heat pipe 3
, And the semiconductor laser 4 can be effectively cooled.

FIGS. 3A and 3B show an LD according to the present invention.
It is a figure showing the 3rd example of composition of a stem. FIG. 3 (a)
3B is a plan view, FIG. 3B is a cross-sectional view taken along line CC ′ of FIG. 3A, and FIG. 3A and FIG.
The same parts as in (a) and (b) are denoted by the same reference numerals.

In the configuration examples of FIGS. 3A and 3B, FIG.
The configuration is the same as the basic configuration of the LD stem of FIG. 2B, except that the semiconductor laser 4 is directly mounted on the heat pipe 3. That is, heat pipe 3
If fine processing is possible, the maximum cooling effect can be obtained by directly mounting the semiconductor laser 4 on the heat pipe 3. Therefore, in the configuration examples of FIGS. 3A and 3B, a substantially flat surface is formed at the end of the heat pipe 3, and the semiconductor laser 4 can be directly mounted on the heat pipe 3. Thereby, the heat from the semiconductor laser 4 is directly transmitted to the evaporating section of the heat pipe 3, and the maximum cooling effect can be obtained. That is, since the semiconductor laser 4 and the heat pipe 3 are in direct contact, the semiconductor laser 4 can be effectively cooled.

FIG. 4 is a diagram showing a fourth configuration example of the LD stem according to the present invention. It should be noted that in FIG.
Parts corresponding to (b) are denoted by the same reference numerals. In the configuration example of FIG. 4, the mounting substrate 19 for mounting the LD system is provided.
The mounting board 19 is provided with a hole 18 through which the heat pipe 3 penetrates. As described above, in the configuration example of FIG. 4, since the hole 18 through which the heat pipe 3 penetrates is formed in the mounting board 19, the heat pipe 3 does not interfere with the mounting.

That is, as described above, the terminals 6 of the OPIC-integrated LD stem using the hologram are arranged in an elliptical shape, and each terminal 6 is connected to the wiring pattern (not shown) of the mounting board 19. I have. In such a configuration, the heat pipe 3 located inside the terminal 6 becomes an obstacle during mounting. Therefore, by adopting a structure in which the hole 18 through which the heat pipe 3 penetrates is formed in the mounting board 19, even if the heat pipe 3 is located inside the terminal 6, the heat pipe 3 does not interfere with the mounting. It gets sick.

Although not shown in FIGS. 1 to 4, a lid member and a hologram element are attached to the upper part of the LD stem of FIGS. 1 to 4 for use. FIG.
Although not shown in FIG. 4 to FIG.
The PIC 5 is used by being connected to the terminal 6 by a wire.

[0030]

As described above, according to the first to seventh aspects of the present invention, the support member for supporting the semiconductor laser and the hermetic terminal are provided on the eyelet.
In the D stem, a through hole is provided in the eyelet and the support member, and the heat pipe is hermetically inserted into the through hole, so that the semiconductor laser (L
D) and the evaporating part of the heat pipe can be brought close to each other, and the heat conduction ability of the heat pipe can be sufficiently extracted to significantly increase the cooling effect of the semiconductor laser. It is possible to provide an LD stem and an optical pickup having a high heat dissipation effect that can be used even with a blue LD having a large value.

In particular, according to the second aspect of the present invention, since the center axis of the heat pipe is deviated from the center axis of the eyelet, the heat pipe is spatially separated from the semiconductor laser on the center axis. Therefore, the evaporating section of the heat pipe can be brought close to the vicinity of the semiconductor laser, and the semiconductor laser can be cooled effectively.

According to the third aspect of the present invention, since the heat pipe is arranged inside the terminal, the semiconductor laser can be effectively prevented without passing through the terminal having a large thermal resistance. Can be cooled.

According to the fourth aspect of the present invention, the LD
Due to the conical engagement between the stem and the heat pipe, even if the size of the support member that supports the semiconductor laser is not large enough to completely penetrate the heat pipe, the heat pipe can be brought close to the semiconductor laser. It is possible to do.

According to the fifth aspect of the present invention, in the LD stem according to the first aspect, the semiconductor laser is directly mounted on the heat pipe. The heat can be directly transmitted to the evaporating section of the heat pipe, and the maximum cooling effect can be obtained.

According to the sixth aspect of the present invention, since a hole through which the heat pipe penetrates is formed in the mounting board, even if the heat pipe is located inside the terminal, the heat pipe is not mounted during mounting. Is not in the way.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first configuration example of an LD stem according to the present invention.

FIG. 2 is a diagram showing a second configuration example of the LD stem according to the present invention.

FIG. 3 is a diagram showing a third configuration example of the LD stem according to the present invention.

FIG. 4 is a diagram showing a fourth configuration example of the LD stem according to the present invention.

FIG. 5 is a configuration diagram of a conventional LD stem.

FIG. 6 is a configuration diagram of a conventional LD stem.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Eyelet 2 Supporting member 3 Heat pipe 4 Semiconductor laser (LD) 5 OPIC 6 Hermetic terminal 7 Glass sealing part

Claims (7)

[Claims] 1. An LD stem in which a support member for supporting a semiconductor laser and an airtight terminal are provided in an eyelet, wherein a through hole is provided in the eyelet and the support member, and a heat pipe is provided in an airtight manner in the through hole. An LD stem inserted in the LD stem. 2. The LD stem according to claim 1, wherein a center axis of the heat pipe is shifted from a center axis of the eyelet. 3. The LD stem according to claim 1, wherein said heat pipe is disposed inside a hermetic terminal. 4. The LD stem according to claim 1, wherein L
An LD stem, wherein the D stem and the heat pipe are conically engaged with each other. 5. The LD stem according to claim 1, wherein a semiconductor laser is directly mounted on said heat pipe. 6. The LD stem according to claim 1, further comprising a mounting substrate for mounting the LD stem, wherein the mounting substrate has a hole through which a heat pipe passes. Characteristic LD stem. 7. An optical pickup, wherein the LD stem according to claim 1 is used.