JPH11251689A - Semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor laser module the coolability of which is not deteriorated even when the thickness of the package of the module itself is reduced. SOLUTION: A carrier 23 and a heat sink are arranged between the cooling- side substrate of an electronic cooling element and a semiconductor laser. The semiconductor laser is faced oppositely to the light entrance end of a hemispherical-ended optical fiber 32. The carrier 25 has a recessed section formed by making the surface of the part of the carrier 25 having the same width as the heat sink has lower than the surface of the other part. Therefore, the electric cooling element is combinedly used with a low first electronic cooling element, and a tall second electronic cooling element and an endothermic reaction efficiently occurs even in the part immediately below the semiconductor laser. In addition, the package of a semiconductor laser module itself can be reduced because of the recessed section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module used for optical communication and information processing, for example, and more particularly to a semiconductor laser module having an electronic cooling element for cooling the inside of the module.

[0002]

2. Description of the Related Art Semiconductor lasers are used not only in the field of optical communication using optical fibers but also in various applications such as printers and compact disks. In the field of optical communication, such a semiconductor laser is usually used as a semiconductor laser module in the form of a module in order to stabilize the output of a light source and facilitate connection with an optical fiber.

For example, in the field of optical communication, transmission devices using optical fibers have been miniaturized, and high integration of circuit boards has been demanded. At the same time, various components incorporated in the circuit board have become smaller and their height has also been reduced. In relation to such components, semiconductor laser modules are also required to be thinner.

FIG. 5 shows an example of a conventionally proposed semiconductor laser module. One end of an optical fiber 13 for transmitting an optical signal is accommodated in one side wall of the module package 12 of the semiconductor laser module 11. An electronic cooling element 14 is arranged on the bottom inside the module package 12. Electronic cooling element 1
A semiconductor laser 16 and a lens 17 for optically coupling a light beam emitted from the semiconductor laser 16 to an optical fiber 13 are disposed on the substrate 4 via a substrate 15.

In this semiconductor laser module, the following contrivance has been made to reduce the height of the module package 12 as much as possible. The electronic cooling element 14 is minimized in thickness to exhibit the required cooling capacity. The substrate 15 disposed thereon is processed so that the portion on which the lens 17 is placed is as thin as possible.
Since the height of the portion on which the semiconductor laser 16 is mounted is set so that the laser beam coincides with the optical axis of the lens 17, this portion requires a certain thickness (height).
The smaller the diameter of the lens 17 is, the lower the height of the module package 12 can be. However, in practice, it is necessary to secure a predetermined aperture angle (NA). Therefore, the smallest diameter that satisfies this requirement is set.

[0006]

As described above, as the thickness of the semiconductor laser module has been reduced, the heat generated by the semiconductor laser itself due to high-density mounting and the rise in the environmental temperature due to the heat generated by components such as ICs (integrated circuits) have been increasing. It is a problem.
This problem becomes more remarkable as the density of the semiconductor laser module increases. Therefore, with the increase in the density, there is also a demand for an improvement in the cooling capacity of the semiconductor laser module.

For example, Japanese Patent Application Laid-Open No. H02-299281 discloses that a concave portion is formed in a substrate on which a semiconductor laser is mounted,
A technology has been disclosed in which a semiconductor laser is embedded in the semiconductor laser to reduce the thickness, and a heat insulating material is applied to a substrate on which the semiconductor laser is mounted to block heat transfer and improve cooling performance. However, in this proposed technique, a semiconductor laser is arranged in a concave portion of a substrate via a heat insulating material. The electronic cooling element is arranged on both sides of the concave part, and the electronic cooling element does not exist in the concave part of the substrate in order to reduce the height of the module. Therefore, there is no electronic cooling element under the semiconductor laser, and there is a problem that the cooling capacity is reduced.
In addition, since the heat insulating material is used, there is a problem that when the heat generation amount of the semiconductor laser itself becomes large, it becomes an obstacle in releasing the generated heat, and the temperature of the semiconductor laser module itself rises.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser module which achieves a reduction in the thickness of the package itself and does not impair the cooling ability.

[0009]

According to the first aspect of the present invention, there are provided (a) a semiconductor laser, (b) a package accommodating the semiconductor laser, and (c) a thermal conductivity for disposing the semiconductor laser. A temperature-controlling substrate which is a good plate-like member having a concave portion recessed toward the bottom surface of the package, the portion corresponding to the semiconductor laser; and (d) the temperature-controlling substrate and the bottom surface of the package. The semiconductor laser module is provided with a temperature adjusting member which is disposed therebetween and whose height is reduced corresponding to the depression of the concave portion, with the element disposed in the concave portion being smaller than the element disposed in the other portion.

In other words, according to the first aspect of the present invention, the portion corresponding to the semiconductor laser in the temperature adjustment substrate in which the semiconductor laser accommodated in the package is fixed directly or indirectly via a predetermined member is positioned in the direction of the bottom surface of the package. Depressed. Then, a low-profile element is disposed as a temperature-controlling member between the concave portion (recess) and the bottom surface of the package corresponding to the concave portion of the temperature-controlling substrate, and a high-profile device is provided in other places. I'm trying to use
Therefore, the portion corresponding to the semiconductor laser on the temperature adjustment substrate is in contact with the element as the temperature adjustment member in the same manner as the other portions, so that the heat energy for adjusting the temperature can be smoothly transferred. In addition, the height of the package can be reduced by the amount corresponding to the depression of the concave portion.

According to the second aspect of the present invention, (a) a semiconductor laser, (b) a plate-shaped heat sink to which the semiconductor laser is fixed, (c) a module package for housing the semiconductor laser therein, and (d) A) a temperature-adjusting substrate which is a plate-like member having good heat conductivity to which a heat sink is fixed and whose portion corresponding to the semiconductor laser is a concave portion recessed toward the bottom surface of the module package; A temperature adjusting member arranged between the substrate and the bottom surface of the module package, wherein the element arranged in the concave portion has a lower height corresponding to the concave portion of the concave portion than the element arranged in the other portion; A laser module is provided.

That is, according to the second aspect of the present invention, the semiconductor laser accommodated in the package is fixed to the substrate for temperature adjustment via the heat sink, and the portion of the substrate for temperature adjustment corresponding to the semiconductor laser is oriented in the direction of the bottom surface of the package. Depressed. Then, a low-profile element is disposed as a temperature-controlling member between the concave portion (recess) and the bottom surface of the package corresponding to the concave portion of the temperature-controlling substrate, and a high-profile device is provided in other places. I'm trying to use Therefore, the portion corresponding to the semiconductor laser on the temperature adjustment substrate is in contact with the element as the temperature adjustment member in the same manner as the other portions, so that the heat energy for adjusting the temperature can be smoothly transferred. In addition, the height of the package can be reduced by the amount corresponding to the depression of the concave portion.

According to a third aspect of the present invention, in the semiconductor laser module according to the first or second aspect, the temperature adjusting member includes two types of electronic cooling elements having different heights. That is, the height of the electronic cooling element corresponding to the concave portion is lower than that of the electronic cooling elements corresponding to the other portions by the depression of the concave portion. However, since the electronic cooling element is in contact with the temperature adjusting member even in the concave portion, the semiconductor laser can be efficiently cooled.

According to the fourth aspect of the present invention, since the concave portion is formed along the shape of the heat sink in the semiconductor laser module according to the second or third aspect, the temperature adjusting member has a high height. Alternatively, more electronic cooling elements can be arranged, and the cooling capacity can be more effectively exerted.

According to the fifth aspect of the present invention, in the semiconductor laser module according to the second or third aspect, since the concave portion is formed as a groove equal to the length of one side of the heat sink, the temperature adjusting member has a high temperature. The adjusting member or the electronic cooling element can be efficiently arranged, and the cooling capacity can be effectively exhibited.

According to the sixth aspect of the present invention, in the semiconductor laser module according to the first or second aspect, the optical fiber disposed to face the emission side of the semiconductor laser is a spherical optical fiber whose end face is spherical. In addition, there is an advantage that it is not necessary to arrange an optical lens between the optical fiber and the semiconductor laser, and the adjustment is easy.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 is a perspective view of the inside of a semiconductor laser module without a module package according to one embodiment of the present invention. In the semiconductor laser module 21 of the present embodiment, the semiconductor laser 22 is disposed on a thin heat sink 23 for improving heat radiation. The heat sink 23 is fixed to the central portion 25A of the carrier 25 arranged on the electronic cooling element 24 by soldering. The width of the central portion 25A is such that it matches the length of the heat sink 23 in this direction. The thermoelectric cooler 24 is used for stabilizing the light output level of the semiconductor laser 22 and for stabilizing the output wavelength. The thermoelectric cooler 24 is fixed to the bottom of a module package (not shown). It has a structure sandwiched between a substrate 26 and a cooling-side substrate 27 fixed to a carrier 25.

The cooling-side substrate 27 is bent so that its central portion is one step lower than both sides. Since the carrier 25 also has a shape along the cooling-side substrate 27, the above-mentioned central portion 25A is further lower than its surroundings. The electronic cooling element 24 is composed of first and second electronic cooling elements 24A and 24B having different heights corresponding to such shapes of the carrier 25 and the cooling side substrate 27. That is, the first electronic cooling element 24A having a relatively short height is disposed immediately below the central portion 25A of the carrier, and the second electronic cooling element 24B having a relatively high height is disposed in other portions. ing.

FIG. 2 shows the semiconductor laser module of this embodiment in a state where the lid is opened and viewed from above, and FIG. 3 shows the cross-sectional structure of the semiconductor laser module in the direction of AA in FIG. Things. In these figures, the module package 31 of the semiconductor laser module is:
Bottom plate 31A, side wall 31B and lid 31 disposed thereon
C. The lid is not shown in FIG.

As shown in FIG. 3, the package side substrate 26 of the electronic cooling element 24 described in FIG. 1 is fixed on the bottom plate 31A of the module package by soldering. Semiconductor laser 22 arranged via cooling side substrate 27 of electronic cooling element 24, carrier 25 and heat sink 23
Are arranged such that the light emission side faces the light incident end of the spherical optical fiber 32. This tip optical fiber 32
Is fixed to the fiber holder 33 by YAG laser welding, and is fitted into the side wall 31B. The tip of the spherical optical fiber 32 has a spherical shape, and condenses the light emitted from the semiconductor laser 22 to realize optical coupling with high efficiency.

The light emitted from the semiconductor laser 22 in the semiconductor laser module according to the present embodiment enters the spherical optical fiber 32 in a spread state. It is taken out by an optical component such as an optical connector (not shown) attached to the camera. Semiconductor laser 2 in module package 31
2 is controlled so as to be cooled by the electronic cooling element 24 to be in a predetermined temperature range. Since the first electronic cooling element 24A is disposed immediately below the heat sink 23 to which the electronic cooling element 24 is attached, the cooling of the semiconductor laser 22 together with the second electronic cooling element 24B disposed around the carrier 25 is performed. Done quickly and efficiently.

Further, in the semiconductor laser module of the present embodiment, the central portion 25A of the carrier corresponding to the position where the semiconductor laser 22 is mounted is lower than the peripheral portion. For this reason, the height of the semiconductor laser 22 can be reduced correspondingly, and the position of the spherical optical fiber 32 can be correspondingly reduced. This makes it possible to reduce the thickness of the semiconductor laser module.

Further, in the semiconductor laser module of this embodiment, the cooling side substrate 27 of the electronic cooling element 24 and the carrier 25
Are formed into a bent shape having a step. As a result, there is no positional shift between the electronic cooling element 24 and the carrier 25. In addition, since the width of the central portion 25A of the carrier is set so as to coincide with the length of the heat sink 23 in this direction, misalignment between components can be prevented as much as possible, and the reliability of the semiconductor laser module can be improved. Become.

Modification

FIG. 4 is a perspective view of the inside of a semiconductor laser module from which a module package according to a modification of the present invention has been removed. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In this modification, the carrier 41 is the semiconductor laser 22
Is formed in the shape of a recess 41A, which is the same size as the portion of the heat sink 23 to which is attached, and is one step lower than the remaining portion. The cooling-side substrate 43 of the electronic cooling element 42 is formed along the shape of the carrier 41 so that only the portion corresponding to the heat sink 23 is concave.

The electronic cooling element 42 has first and second electronic cooling elements 42A and 42B having different heights corresponding to such a shape of the carrier 41 and the cooling side substrate 43.
It is composed of That is, the first electronic cooling element 42A having a relatively short height is disposed immediately below the concave portion 41A of the carrier, and the second electronic cooling element 42A having a relatively high height is provided in other portions.
Of the electronic cooling element 42B are arranged. Compared with the case of the previous embodiment, the ratio of the first electronic cooling element 42A is smaller and the ratio of the second electronic cooling element 42B is larger. Therefore, the cooling capacity for the semiconductor laser 22 is improved as compared with the previous embodiment.

Moreover, since the heat sink 23 has the same size as the surface of the concave portion 41A, the mounting position of the heat sink 23 is fixed not only in the direction orthogonal to the axial direction of the optical fiber but also in the axial direction. The reliability of the semiconductor laser module is further improved.

In the embodiment and the modification, the spherical optical fiber 32 is opposed to the emission side of the semiconductor laser 22.
Naturally, one or a plurality of optical lenses may be arranged between them using a normal optical fiber.

[0031]

As described above, according to the first aspect of the present invention, the portion of the temperature adjusting substrate corresponding to the semiconductor laser is depressed toward the bottom surface of the package, so that the temperature adjusting member comes into contact with the temperature adjusting member. The surface will also be depressed toward the bottom in response to this, not only contributing to the thinning of the package, but also stabilizing the positional relationship between the temperature adjustment substrate and the temperature adjustment member and improving the reliability of the semiconductor laser module. Can be improved.

According to the second aspect of the invention, the same effect as that of the first aspect of the invention can be obtained. In addition, since the heat sink is arranged between the semiconductor laser and the substrate for temperature adjustment, Can be dissipated more effectively.

Further, according to the third aspect of the present invention, since the temperature adjusting member is composed of two types of electronic cooling elements having different heights, various types of electronic cooling elements having different heights are prepared. Without cooling, the semiconductor laser can be efficiently cooled.

According to the fourth aspect of the present invention, since the concave portion is formed along the shape of the heat sink, more temperature adjusting members or electronic cooling elements are arranged on the temperature adjusting member. And the cooling capacity can be more effectively exerted.

According to the fifth aspect of the present invention, the recess is formed as a groove having a length equal to the length of one side of the heat sink, so that a high temperature adjusting member or an electronic cooling element can be used as the temperature adjusting member. It is possible to arrange the heat sink efficiently and not only to exert the cooling capacity effectively, but also to freely set the length of the other side of the heat sink.

According to the sixth aspect of the present invention, the optical fiber disposed opposite to the emission side of the semiconductor laser is a spherical optical fiber having a spherical end surface. There is no need to dispose lenses, which facilitates adjustment and further contributes to downsizing of the module.

[Brief description of the drawings]

FIG. 1 is a perspective view of a semiconductor laser module without a module package according to an embodiment of the present invention.

FIG. 2 is a plan view showing a state in which a lid of the semiconductor laser module of the present embodiment is opened and viewed from above.

FIG. 3 is a cross-sectional view illustrating a cross-sectional structure of the semiconductor laser module taken along a line AA in FIG. 2;

FIG. 4 is a perspective view of a semiconductor laser module without a module package according to a modification of the present invention.

FIG. 5 is a schematic configuration diagram illustrating an example of a conventionally proposed semiconductor laser module.

[Explanation of symbols]

 Reference Signs List 22 semiconductor laser 23 heat sink 24, 42 thermoelectric cooling element 24A first thermoelectric cooling element 24B second thermoelectric cooling element 25, 41 carrier 25A central part (recess) of carrier 25 27, 43 cooling side substrate 31 module package 32 front sphere Optical fiber

Claims (6)

[Claims] 1. A semiconductor laser, a package accommodating the semiconductor laser therein, and a plate-like member having good thermal conductivity on which the semiconductor laser is disposed, the portion corresponding to the semiconductor laser being a bottom surface of the package. A temperature adjusting substrate that is a concave portion that is depressed in the direction, disposed between the temperature adjusting substrate and the bottom surface of the package, and an element disposed in the concave portion is smaller than an element disposed in other portions. A semiconductor laser module comprising: a temperature adjusting member having a height corresponding to a depression of a recess. 2. A semiconductor laser, a plate-like heat sink to which the semiconductor laser is fixed, a module package for housing the semiconductor laser therein, and a plate-like member having good thermal conductivity to which the heat sink is fixed. A substrate for adjusting the temperature, the portion corresponding to the semiconductor laser being a concave portion recessed toward the bottom surface of the module package; and a substrate disposed between the temperature adjusting substrate and the bottom surface of the module package, and disposed in the concave portion. A semiconductor laser module, comprising: a temperature adjusting member having a lower height corresponding to a depression of a concave portion than an element disposed in another portion. 3. The semiconductor laser module according to claim 1, wherein the temperature adjusting member comprises two types of electronic cooling elements having different heights. 4. The semiconductor laser module according to claim 2, wherein the recess is formed along the shape of the heat sink. 5. The semiconductor laser module according to claim 2, wherein the heat sink has a rectangular parallelepiped shape, and the recess is formed as a groove having a length equal to one side of the heat sink. 6. The semiconductor laser module according to claim 1, wherein the optical fiber arranged to face the emission side of the semiconductor laser is a spherical optical fiber having a spherical end surface.