JP2000294868A - Semiconductor laser module and Peltier module used for semiconductor laser module - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a semiconductor laser module that can be used under high output and high environmental temperature. SOLUTION: When a substrate 16 on which a semiconductor laser element 13 is fixed is fixed to a cooling-side substrate of a Peltier module 12 fixed to a package 11, the semiconductor laser element 13 is arranged at a substantially central portion of the Peltier module 12. Fixed. The Peltier module 12 has a larger heat absorption amount in the peripheral part than in the central part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor laser module, and more particularly to a semiconductor laser module suitable for use in a high-temperature environment and a Peltier module suitable for a semiconductor laser module.

[0002]

2. Description of the Related Art In recent years, semiconductor lasers have been used in large quantities as signal light sources and optical fiber amplifier excitation light sources in optical communications. When a semiconductor laser is used as a signal light source or an excitation light source in optical communication, it is often used as a semiconductor laser module that is a device in which laser light from a semiconductor laser is optically coupled to an optical fiber.

FIG. 6 shows an example of the structure of such a semiconductor laser module. In a semiconductor laser module 40 shown in FIG. 6, a Peltier module 42 is fixed to a package bottom plate 11a in a package 11. The substrate 16 on which the semiconductor laser element 13, the thermistor 14, and the lens 15 are fixed is fixed on the Peltier module 42. Package 11
An optical fiber 17 is fixed to a through hole 11c provided in the side wall 11b. In FIG. 6, reference numeral 50 denotes a heat sink.

In the semiconductor laser module 40, the laser light emitted from the semiconductor laser
The light is condensed by the optical fiber 17 and is incident on the end face of the optical fiber 17, which is guided through the optical fiber 17 and used for a desired application.

In the semiconductor laser module 40, when a current is applied to drive the semiconductor laser element 13, the temperature of the semiconductor laser element 13 rises due to heat generation. This rise in temperature causes a change in the oscillation wavelength and light output of the semiconductor laser device 13.

For this reason, the semiconductor laser device 13 is fixed by a thermistor 14 fixed near the semiconductor laser device 13.
By controlling the current flowing through the Peltier module 42 using the measured value, the temperature of the semiconductor laser element 13 is kept constant to stabilize the characteristics.

A Peltier module 42 used in a semiconductor laser module 40 generally has a structure as shown in FIG.
A P-type thermoelectric conversion element 18 as a P-type semiconductor and an N-type thermoelectric conversion element 19 as an N-type semiconductor are alternately arranged and arranged between two insulating layers 12 a and 12 b made of, for example, ceramic. A thermoelectric conversion element 18 and an N-type thermoelectric conversion element 19 are electrically connected in series. By applying a DC voltage to the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19, heat is generated or absorbed on the surfaces of the insulating layers 12a and 12b, thereby heating or cooling the object.

FIG. 7 (a) shows a cross section of the Peltier module 42.
A P-type thermoelectric conversion element 18 is provided between two ceramic insulating substrates 12a and 12b made of alumina or aluminum nitride.
And an N-type thermoelectric conversion element 19 are sandwiched. These thermoelectric elements 18 and 19 are electrically connected by electrodes 12c formed on the surfaces of the insulating substrates 12a and 12b.

FIG. 7B is a perspective view of the Peltier module 42 with the insulating substrates 12a and 12b omitted. The Peltier module 42 includes a large number of thermoelectric conversion elements 1.
8 and 19 are formed on the insulating substrates 12a and 12b so as to be uniformly arranged two-dimensionally.

FIG. 7 (c) shows each thermoelectric effect element 18, 19
Of the P-type thermoelectric conversion element 18 and N
The thermoelectric conversion elements 19 are alternately connected in series.

Although the number of thermoelectric elements 18 and 19 to be connected varies depending on the application, for example, a semiconductor laser module in which the number of P-type thermoelectric conversion elements 18 and N-type thermoelectric conversion elements 19 is 20 to 40 is used. It is commonly used for applications.

Such a Peltier module 42 is manufactured as follows. First, an ingot is prepared from a raw material powder mainly containing bismuth (Bi) and tellurium (Te) by a single crystal method or a hot press method, and cut into chips to form a P-type thermoelectric conversion element 18 and an N-type thermoelectric element. The conversion element 19 is manufactured (for example, a known technique disclosed in JP-A-1-202343 or JP-A-1-106478).

Next, as shown in FIG. 8A, a plurality of electrodes 12c are provided on an insulating substrate 12a and each electrode 1c is provided.
A solder paste 12e is applied on 2c. Next, FIG.
As shown in (b), the chip-shaped P-type thermoelectric conversion elements 18 are mounted one by one on each electrode 12c. Thereafter, as shown in FIG. 8 (c), the chip-shaped N-type thermoelectric conversion elements 19 are mounted one by one on each electrode 12c, whereby the P-type thermoelectric conversion elements 18 and the N-type thermoelectric conversion elements 19 are formed. Are arranged alternately.

A plurality of electrodes 12c are provided on the insulating substrate 12b and a solder paste 12e is applied on each of the electrodes 12c in the same manner as in FIG. ), The P-type thermoelectric conversion element 18
And on the insulating substrate 12a on which the N-type thermoelectric conversion elements 19 are mounted, the electrodes 12c are arranged so as to straddle each other,
The upper insulating substrate 1 is attached to the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19 on the electrode 12c of the lower insulating substrate 12a.
The adjacent electrode 12c of 2b is overlapped.

In this state, the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19 are joined between the two insulating substrates 12a and 12b by reflowing the solder paste 12e in a solder reflow furnace (not shown). At the same time, the P-type thermoelectric conversion element 18 and the N-type
Peltier module 42 as shown in FIG.

The reason why the heating and cooling effects are generated by energizing the Peltier module is explained as follows. That is, when a DC voltage is externally applied to the Peltier module 42 as shown in FIG. 7A, the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19 are sandwiched between the two insulating substrates 12a and 12b and Since they are electrically connected in series alternately, a current flows from the insulating substrate 12a to the insulating substrate 12b in the P-type thermoelectric conversion element 18 and from 12b to 12a in the N-type thermoelectric conversion element 19. Flows.

However, holes are majority carriers in the P-type thermoelectric conversion element 18 and electrons are majority carriers in the N-type thermoelectric conversion element 19. The movement of the particles carrying the current occurs in the direction from the insulating substrates 12a to 12b. On the other hand, holes and electrons that carry this current also carry heat transfer. For this reason, while the current flows in the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19 in opposite directions to each other, the heat flow always occurs in one direction. Cooling occurs on one side and heating occurs on the other side.

The thermal environment during operation of the semiconductor laser module 40 shown in FIG. 6 having such a Peltier module 42 will be described below.

When the semiconductor laser module 40 is mounted and used in a communication device such as an optical fiber amplifier, heat is generated from other semiconductor laser modules and electric circuit elements to be mounted at the same time, and the location of the communication device is set. Depending on the environment, it is often used at an environmental temperature higher than room temperature. For this reason, the semiconductor laser module 40 is usually used by being fixed to the heat sink 50 in order to use the semiconductor laser module 40 in a state of high heat dissipation efficiency.

FIG. 9 shows that the semiconductor laser module 40
This is a diagram schematically showing a thermal environment when used while being fixed to the heat sink 50. In the drawing, the lens 15 and the optical fiber 17 are omitted for the sake of explanation.

As shown in FIG. 9, the ambient temperature where the semiconductor laser module 40 is placed is Ta, and the temperature of the heat sink 50 is Ths. Here, when a current is supplied to the semiconductor laser element 13 while keeping the temperature (thermistor temperature) Ts of the thermistor 14 constant, the amount of heat QLD generated from the semiconductor laser element 13 is transmitted through the substrate 16 to the cooling side of the Peltier module 42. , And then the heat is discharged toward the insulating substrate 12b on the heating side.

At the same time, the heat generation QTM of the Peltier module itself due to the current flowing through the Peltier module 42 is also discharged to the insulating substrate 12b. Then, the heat (QLD + QTM) is discharged to the heat sink 50 via the bottom plate 11a of the package 11.

The temperature of the insulating substrate 12a on the cooling side and the temperature of the insulating substrate 12b on the heating side of the Peltier module 42 are set to T, respectively.
c, Th, semiconductor laser element 13 and cooling side insulating substrate 12
Assuming that the thermal resistance between the heat sink and the heat sink 50 is K1 and the thermal resistance between the heating side insulating substrate 12b and the heat sink 50 is K2, Th = Ths + K2 (QLD + QTM) (1) Tc = Ts−K1QLD · (2) Since there is a relationship, the temperature difference ΔT = Th−Tc between the insulating substrates 12 a and 12 b of the Peltier module 42 is ΔT = (Ths−Ts) + (K1 + K2) QLD + K2 QTM (3)

In the equation (3), (Ths−
Ts) means an inside / outside temperature difference when used as the semiconductor laser module 40.

That is, according to the equation (1), the presence of the thermal resistor K 2 between the insulating substrate 12 b on the heating side and the heat sink 50 allows the heating side substrate 12 of the Peltier module 42 to be mounted.
The temperature Th of b is K2 compared to the temperature Ths of the heat sink.
(QLD + QTM).

From the equation (2), the semiconductor laser element 13
The thermal resistance K1 exists between the cooling side insulating substrate 12a and the temperature Tc of the cooling side insulating substrate 12a.
Is lower by K1 QLD than the thermistor temperature (temperature of the semiconductor laser element) Ts.

Thus, the temperature difference between inside and outside (Ths-Ts) when the semiconductor laser module 40 is used.
Is the temperature difference ΔT between the insulating substrates of the Peltier module 42
Is smaller by (K1 + K2) QLD + K2QTM.

[0028]

By the way, recently, the above-mentioned semiconductor laser module has been required to operate at a high optical output and a high environmental temperature in accordance with an increase in the output of the entire system. Have been.

When the output power of the semiconductor laser device is increased to increase the output power of the semiconductor laser module, the heat generation (QLD) necessarily increases. In order to use such a high-output semiconductor laser module in a high-temperature environment, heat generated from the semiconductor laser element must be efficiently discharged as compared with the related art.

However, the above-described conventional semiconductor laser module has the following problems.

Referring to the semiconductor laser module 40 shown in FIG. 9, the heat quantity QLD generated from the semiconductor laser element 13 is discharged to the heat sink 50 via the substrate 16, the Peltier module 42, and the package bottom plate 11a.

Here, since the thickness of the entire semiconductor laser module 40 is designed to be thin to a predetermined thickness for the reason of mounting on a device, the substrate 16 and the package bottom plate 11a are also designed to be thin. Therefore, while the heat QLD generated from the semiconductor laser element 13 is conducted through the substrate 16 in the thickness direction and through the bottom plate 11a of the package, the heat sink 50
Is not sufficiently spread in the lateral direction (direction parallel to the surface of the insulating substrate 12a or 12b of the Peltier module) until the heat is exhausted.

Further, since heat is transferred by the Peltier module 42 through holes and electrons inside the thermoelectric conversion element, it does not spread in the horizontal direction in principle.

That is, the amount of heat QLD generated from the semiconductor laser device 13 flows intensively immediately below the semiconductor laser device and in the vicinity thereof and is discharged to the outside. For this reason, the effective thermal resistance of the path of the discharged heat is larger than when it is assumed that the heat spreads sufficiently and is uniformly discharged.

This is because K in equations (1) to (3)
It means that the effective values of 1 and K2 are large. When the semiconductor laser module is used in such a situation where the effective heat resistance of the exhaust heat is large, the temperature difference caused by the heat resistance becomes larger than when it is assumed that the heat is uniformly exhausted. .

This temperature difference is caused by the
3 becomes more remarkable as the calorific value QLD generated increases and the semiconductor laser module 40 is used under a higher ambient temperature (when QTM is larger).

When the semiconductor laser module 40 is used in such a situation, the temperature difference ΔT between the heating-side and cooling-side insulating substrates 12a and 12b of the Peltier module 42 becomes very large, and the load of the Peltier module 42 becomes large. And its power consumption increases, which causes a vicious cycle of further raising the environmental temperature.

Therefore, in order to increase the output of the semiconductor laser module and use it in a higher temperature environment, it is necessary to make the flow of heat from the semiconductor laser element 13 to the heat sink 50 uniform. For this purpose, the thickness of components existing on the path of exhaust heat, such as the substrate 16 and the bottom plate 11a of the package, may be increased so that the heat is diffused in the lateral direction. As described above, since the thickness of the component is limited by the mounting condition of the semiconductor laser module to the device, such a measure cannot be practically adopted.

The present invention has been made to solve the problem of heat exhaustion of the above-described conventional semiconductor laser module, and has as its object to increase the thickness of parts used in the semiconductor laser module. Uniform heat flow from the semiconductor laser element to the heat sink reduces the temperature difference between the heat sink and the heating-side substrate of the Peltier module and the temperature difference between the thermistor and the cooling-side substrate of the Peltier module, thus reducing the load on the Peltier module. It is another object of the present invention to provide a semiconductor laser module which consumes less power and has a higher light output and can be used at a higher ambient temperature.

[0040]

In order to achieve the above-mentioned object, the present invention has the following structure to solve the problem.

That is, the first invention of the semiconductor laser module comprises: a semiconductor laser device; a substrate on which the semiconductor laser device is mounted; an optical fiber for receiving light emitted from the semiconductor laser device; An optical coupling means interposed between a laser element and the optical fiber for optically coupling laser light emitted from the semiconductor laser element to the optical fiber; and cooling the substrate on which the semiconductor laser element is mounted. A semiconductor laser module having a Peltier module, a package for accommodating the semiconductor laser element, the substrate, and the Peltier module, wherein the semiconductor laser element is disposed substantially above a central portion of the Peltier module, and the Peltier module Heat absorption is small at the center and large at the periphery. And a means for solving the problems with the configuration that is.

Further, the second invention of the semiconductor laser module includes a semiconductor laser device, a substrate on which the semiconductor laser device is mounted, a Peltier module for cooling the substrate, the semiconductor laser device, the substrate and A semiconductor laser module having a package containing a Peltier module, wherein the heat is discharged from the semiconductor laser element formed including the substrate, the Peltier module, and a bottom plate of the package on which the Peltier module is mounted. The problem is solved by a configuration in which at least a part of the heat discharge path is formed with a heat diffusion portion having a higher thermal conductivity of heat in a direction perpendicular to the direction from the semiconductor laser device to the Peltier module than in the direction. Means.

According to a third aspect of the semiconductor laser module, in addition to the configuration of the second aspect, a heat diffusion portion is formed in a Peltier module fixing region on the bottom plate of the package, and a fiber is formed as the heat diffusion portion. This is a means for solving the problem by using a structure in which a reinforced composite material is used and an airtight holding portion having no air permeability is formed outside the Peltier module fixing region.

According to the fourth aspect of the semiconductor laser module, in addition to the configuration of any one of the first to third aspects, the Peltier module includes a plurality of P-type and N-type thermoelectric conversion element pairs. Solving the problem with a configuration having two ceramic plates sandwiching the plurality of thermoelectric conversion element pairs, wherein the plurality of thermoelectric conversion element pairs are arranged on the ceramic plate such that the peripheral portion is more densely arranged than the substantially central portion. Means to do that.

According to a fifth aspect of the semiconductor laser module, in addition to the configuration of any one of the first to fourth aspects, the Peltier module includes a plurality of P-type and N-type thermoelectric conversion element pairs. Having two ceramic plates sandwiching the plurality of thermoelectric conversion element pairs, wherein the plurality of thermoelectric conversion element pairs include a plurality of first thermoelectric conversion element pairs electrically connected in series with a first portion. And a second part connected in parallel, and a thermoelectric conversion element pair corresponding to the first part is disposed around the ceramic plate and corresponds to a second part. The configuration is such that the pair is arranged at a substantially central portion of the ceramic plate as a means for solving the problem.

Further, the first aspect of the present invention of the Peltier module is a means for solving the problem with a configuration in which the heat absorption is small in the substantially central portion and large in the peripheral portion.

Further, according to the second aspect of the Peltier module, in addition to the first aspect, a plurality of P-type and N-type thermoelectric conversion element pairs, and a plurality of P-type and N-type thermoelectric conversion element pairs sandwiching the plurality of thermoelectric conversion element pairs are provided.
Means for solving the problem include a structure having a plurality of insulating layers, wherein the plurality of thermoelectric conversion element pairs are arranged such that the peripheral portion is more densely arranged than the substantially central portion between the insulating layers.

Further, according to the third invention of the Peltier module, in addition to the first invention, a plurality of P-type and N-type thermoelectric conversion element pairs and a pair of the Peltier module sandwiching the plurality of thermoelectric conversion element pairs are provided.
A plurality of thermoelectric conversion element pairs, wherein the plurality of thermoelectric conversion element pairs were connected in parallel with a first portion in which individual thermoelectric conversion element pairs were electrically connected in series and a plurality of thermoelectric conversion element pairs. A thermoelectric conversion element pair corresponding to the first part is disposed at a peripheral part between the insulating layers, and a thermoelectric conversion element pair corresponding to the second part is substantially at a central part between the insulating layer insulating layers. The means for solving the problem is provided by the configuration arranged in the above.

In the present invention having the above structure, the heat absorption of the Peltier module is formed so as to be larger at the peripheral portion than at the substantially central portion where the semiconductor laser device is arranged. The temperature distribution on the substrate is lower in the peripheral portion, so that the heat transfer based on the temperature gradient from the substantially central portion to the peripheral portion on the substrate occurs more effectively.

If the thermal conductivity in the plane parallel to the cooling surface of the Peltier module of the substrate on which the semiconductor laser element is fixed is larger than the thermal conductivity in the direction perpendicular to the cooling surface of the Peltier module, In the above, it is possible to increase the amount of heat transfer from the substantially central portion to the peripheral portion.

Further, the thermal conductivity in a plane parallel to the heating surface of the Peltier module of the fiber reinforced composite material provided in the bottom plate of the package to which the heating side substrate of the Peltier module is fixed or the Peltier module fixing region of the bottom plate is vertical. If the thermal conductivity is larger than the thermal conductivity in a certain direction, it is possible to increase the amount of heat transfer from the substantially central portion to the peripheral portion on the bottom plate of the package.

For this reason, heat generated from the semiconductor laser element is discharged in a more uniform state in a plane parallel to the insulating substrate surface of the Peltier module.
The above-mentioned problem is solved by reducing the effective thermal resistance of the exhaust heat path.

[0053]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the overlapping description will be omitted.

FIG. 1 shows an example to which an embodiment of a semiconductor laser module according to the present invention is applied.

As shown in FIG. 1, the semiconductor laser module 10 of this embodiment has a semiconductor laser element 13 fixed to a substrate 16. (Although not shown, the semiconductor laser element 13 may be fixed to the substrate 16 via a heat sink such as AlN (aluminum nitride)). The substrate 16 is solder-fixed on the Peltier module 12 fixed on the bottom plate 11a of the package 11 by soldering at a position where the semiconductor laser element 13 is arranged above a substantially central portion of the Peltier module 12.

The through hole 11 in the side wall 11b of the package 11
The optical fiber 17 is fixed to c. The optical fiber 17 is fixed at a position where the light from the semiconductor laser element 13 condensed by the lens fixed on the substrate 16 is coupled.

A thermistor 14 is fixed on the substrate 16 near the semiconductor laser device 13. The semiconductor laser module 10 includes a substrate 16, a Peltier module 12, and a bottom plate 11a of the package 11,
A heat discharge path for discharging heat from the semiconductor laser element 13 is formed.

Here, in the Peltier module 12 used in the semiconductor laser module 10 according to the present invention, the heat absorption amount in the peripheral portion is larger than the heat absorption amount in the substantially central portion immediately below the semiconductor laser element 13. FIG. 2 shows an example of the arrangement of thermoelectric conversion elements on the heating-side substrate 12b and the cooling-side substrate 12a of the Peltier module 12 and an example of an electrode pattern.

FIG. 2A shows the heating side substrate 12b viewed from the cooling side substrate 12a, and FIG. 2B shows the cooling side substrate 12a.
FIG. 5 is a view as viewed from a heating-side substrate 12b.

2 (a) and 2 (b), the P-type thermoelectric conversion elements 18 and the N-type thermoelectric conversion elements 19 are arranged closer to the periphery and sparser to the center, and they are connected in series by the electrode 12c. Have been. Here, each thermoelectric conversion element 1
8 and 19 are the same, the thermoelectric conversion elements 18 and 19 are moved from the cooling side substrate 12a to the heating side substrate 1a.
The amount of heat transferred to 2b is equal in each of the P-type thermoelectric conversion element 18 and the N-type thermoelectric conversion element 19. Therefore,
The peripheral portion where the thermoelectric conversion elements 18 and 19 are densely arranged has a larger heat absorption amount, and the center portion where the thermoelectric conversion elements 18 and 19 are sparsely arranged has a smaller heat absorption amount in the Peltier module 12.

Note that such a Peltier module 12
Can be manufactured by the same method as a conventionally known method of manufacturing a Peltier module, except that the formation positions of the electrode patterns on the insulating substrates 12a and 12b and the arrangement of the thermoelectric conversion elements are changed.

FIG. 3 shows another example of the arrangement of the thermoelectric conversion elements 18 and 19 and the electrode pattern on the heating side substrate 12b and the cooling side substrate 12a of the Peltier module 22 used in the semiconductor laser module of the present invention. It is shown. 3A is a view of the heating-side substrate 12b viewed from the cooling-side substrate 12a, FIG. 3B is a view of the cooling-side substrate 12a viewed from the heating-side substrate 12b, and FIG. 4 is FIG. FIG. 3 is a diagram illustrating electrical wiring of each thermoelectric conversion element of a Peltier module. In the present embodiment, the thermoelectric conversion elements are arranged and fixed two-dimensionally uniformly. The electrical connection between the thermoelectric conversion elements 18 and 19 is, as shown in FIG.
There is a first portion 20 connected in series, and a second portion 21 connected in parallel.
As shown in FIG. 3A and FIG. 3B, the first portion 20 is arranged at a peripheral portion, and the second portion 21 is arranged at a substantially central portion.

In such a Peltier module 22, the current flowing per thermoelectric conversion element in the second portion 21 is smaller than the current flowing per thermoelectric conversion element in the first portion 20. Therefore, the second part 2
The amount of heat carried by one thermoelectric conversion element in the first portion 20 is smaller than the amount of heat carried by one thermoelectric conversion element in the first portion 20. Therefore, the thermoelectric conversion elements 18 and 19 of the first portion 20 are located in the peripheral portion, and the thermoelectric conversion elements 1 and 2 of the second portion are
By arranging 8 and 19 in the substantially central portion, a Peltier module 22 having a small heat absorption amount in the substantially central portion and a large heat absorption in the peripheral portion can be obtained.

The Peltier module 1 shown in FIG. 2 (or FIG. 3) has a small heat absorption amount at a substantially central portion and a large heat absorption amount at a peripheral portion.
2 (or the Peltier module 22) is used for the semiconductor laser module 10, the semiconductor laser element 13
To the Peltier module 12 (or Peltier module 2
It is desirable to dispose it in the substantially central part of 2).

That is, since the heat absorption of the Peltier module 12 (or the Peltier module 22) is formed to be larger at the peripheral portion than at the substantially central portion where the semiconductor laser element 13 is fixed, the conventional Peltier module is used. 42 compared with the case where the semiconductor laser device 13 is used.
The temperature distribution on the substrate 16 to which is fixed is lower at the peripheral portion of the semiconductor laser device 13.

Therefore, the heat transfer based on the temperature gradient from the substantially central portion where the semiconductor laser element 13 is fixed on the substrate 16 toward the peripheral portion occurs more effectively.

As a result, the flow of the exhaust heat can be extended to the peripheral portion, and the effective heat resistance of the exhaust heat path decreases. Then, the heating-side substrate 12b and the cooling-side substrate 1 of the Peltier module 12 (or the Peltier module 22)
The temperature difference of 2a is reduced and the Peltier module 12
The load on the (or Peltier module 22) is reduced, and the semiconductor laser module 10 that can operate at a higher temperature and consumes less power is obtained.

The Peltier module used in the semiconductor laser module 10 of the present embodiment is not limited to the Peltier module 12 or the Peltier module 22 shown in FIG. 2 or FIG. Needless to say, the above operation can be achieved as long as it is small in the part and large in the peripheral part.

For example, the thermoelectric conversion elements 18, 1 shown in FIG.
It goes without saying that, as the wiring method 9, various combinations of serial and parallel connection methods are also possible.

Further, in the present invention, the thermal conductivity in a plane parallel to the cooling surface of the Peltier module is larger than the thermal conductivity in a direction perpendicular to the cooling surface of the Peltier module (that is, from the semiconductor laser device to the Peltier module). (The thermal conductivity in the direction perpendicular to the direction is larger than that in the direction.) By manufacturing the substrate 16 for fixing the semiconductor laser element 13 with a material having thermal conduction anisotropy, the heat from the semiconductor laser element 13 is also transferred in the horizontal direction. Thus, the same operation as the above-described operation can be obtained.

The substrate 16 having such heat conduction anisotropy
As a material of the above, a fiber reinforced composite material using a metal as a matrix can be used. Examples of such a composite material include carbon (C) and alumina (Al ₂ O).
₃ ) A material in which silicon carbide (SiC) or the like is used as a dispersing material and copper (Cu), molybdenum (Mo), tungsten (W), aluminum (Al), titanium (Ti), or the like is used as a matrix is known. .

The method for producing such a composite material is as follows, for example, as a composite material using copper or a copper alloy as a matrix and carbon fibers as a dispersing material. That is,
A powder of copper powder or copper alloy powder, molybdenum powder or tungsten powder or a mixture thereof is mixed with carbon and / or graphitic fiber by a method such as a ball mill, and the raw material mixture is pressed to form a compression molded product of the mixture. This is further compressed uniaxially by hot isostatic pressing. In the composite material produced in this manner, fibers made of carbon and / or graphite are randomly oriented in the two-dimensional plane direction perpendicular to the compression direction of the metal matrix. Such a composite material and a method for producing the same are disclosed in, for example, JP-A-11-140559.

By using the above-described composite material to form the upper surface and the lower surface of the substrate 16 so as to be parallel to the orientation surface of the carbon fiber, the thermal conductivity in the plane parallel to the cooling surface of the Peltier module 12 can be improved. A substrate having heat conduction anisotropy that is higher than the heat conductivity in the direction perpendicular to the cooling surface of the Peltier module 12 is obtained. Note that it is not necessary to form the entirety of the substrate 16 with the above-described composite material, and a sufficient effect can be obtained simply by forming a part of the substrate 16 with the above-described composite material.

In the case where the entire substrate 16 is formed of a composite material, the thermal conductivity in the plane parallel to the cooling surface of the Peltier module 12 and the thermal conductivity in the direction perpendicular thereto are about 250 W, for example.
/ MK, 100 W / mK. In addition, it is also possible to make the orientation direction of the fiber one-dimensional instead of two-dimensional, and in this case, a larger heat conduction anisotropy can be obtained.

As the heat conductive anisotropic material, for example, a carbon material having heat conductive anisotropy such as that sold by Advanced Ceramics (USA) can be used. As such a carbon material, a material having a maximum thermal conductivity of about 1700 W / mK is also available. Such a carbon material may be coated with a metal, or the insulating substrate of the Peltier module 12 such as alumina or aluminum nitride may be used. By coating the carbon material with SiC / Al (thermal expansion coefficient: 6.7 ppm / ° C.) having a thermal expansion coefficient close to that of the above, the present invention can be suitably applied to the present invention.

By using the substrate 16 having the heat conduction anisotropy as described above, the semiconductor laser device 1
3 efficiently spreads in a direction parallel to the cooling surface of the Peltier module 12, so that the effective thermal resistance of the exhaust heat is reduced. As a result, the load on the Peltier module 12 is reduced, the semiconductor laser module 10 can operate even in a high-temperature environment, and consumes less power. Further, the substrate 1 made of a material having such heat conduction anisotropy
If the Peltier module 6 is used simultaneously with the Peltier module 12 having a small heat absorption amount in the central portion and a large heat absorption amount in the peripheral portion, the effect of the present invention becomes more remarkable.

Further, in addition to the substrate 16 on which the semiconductor laser element 13 is fixed, the bottom plate 11a of the package 11 is made of a material having such heat conduction anisotropy by using a material parallel to the heating surface of the Peltier module 12. If the thermal conductivity is higher than the thermal conductivity in the direction perpendicular to the heating surface of the Peltier module 12, the effect of the present invention becomes more remarkable.

When the bottom plate 11a is formed of a material having the above-described heat conduction anisotropy, for example, a fiber-reinforced composite material such as Cu-C in which copper or a copper alloy is used as a matrix and carbon dispersion materials are arranged. It is possible that the package 11 cannot be airtight. This is because such a fiber-reinforced composite material has fine holes caused by holes formed in accordance with the arrangement of the dispersing materials, and has air permeability.

Therefore, as shown in FIGS. 5A and 5B, for example, a fiber-reinforced composite having heat conduction anisotropy such as Cu-C is provided on the bottom plate 11a of the package 11 in the region where the Peltier module 12 is fixed. The fiber reinforced composite material 30 is provided with a copper tungsten alloy (Cu-W) or a Kovar (F
It is good to arrange | position on the bottom plate 11a (the airtight holding | maintenance part of this invention) of the board | plate material which consists of a material which does not have air permeability like metal materials, such as a trademark of e-Ni-Co alloy. That is, it is preferable to form an airtight holding portion having no air permeability outside the fixing region of the Peltier module 12. And the bottom plate 11 of this metal material
If the package 11 is formed by adhering and fixing the side wall 11b to a, the airtightness of the package 11 can be ensured, and the above effects of the present invention can be remarkably exhibited.

In the configuration example shown in FIG. 9A, a region where the Peltier module 12 is fixed on the bottom plate 11a is cut out, and a fiber reinforced composite material 30 made of a plate material such as Cu-C is embedded in the cutout portion. The fixing of the fiber reinforced composite material 30 to the bottom plate 11a is performed by, for example, silver brazing. In addition, the configuration example shown in FIG.
This is an example in which a fiber reinforced composite material 30 is bonded and fixed to the upper side of the Peltier module 12, and the Peltier module 12 is fixed on the fiber reinforced composite material 30. To simplify the drawing, the Peltier module 12 is fixed to the bottom plate 11a. Only the configuration around the part is shown.

[0081]

As described above, according to the semiconductor laser module of the present invention, the heat absorption of the Peltier module is formed to be larger at the peripheral portion than at the substantially fixed central portion of the semiconductor laser device. Therefore, the temperature distribution on the substrate on which the semiconductor laser device is fixed is lower at the peripheral portion of the semiconductor laser device, and the temperature gradient from the substantially central portion where the semiconductor laser device is fixed on the substrate toward the peripheral portion is reduced. The heat transfer based on the heat generation occurs more effectively.
As a result, the flow of the discharged heat can be extended to the peripheral portion without increasing the thickness of the semiconductor laser module, and the effective heat resistance of the heat discharge path is reduced. As a result, the temperature difference between the insulating substrate on the cooling side and the insulating substrate on the heating side of the Peltier module is reduced and the load on the Peltier module is reduced. As a result, a semiconductor laser module that can operate at a higher temperature and consumes less power can be manufactured. .

Further, at least a part of a heat discharging path for discharging heat from the semiconductor laser element, which is formed including a substrate, a Peltier module, and a bottom plate of a package on which the Peltier module is mounted, includes the semiconductor laser. According to the present invention, in which the heat diffusion portion having a higher thermal conductivity of heat in a direction perpendicular to the direction from the element toward the Peltier module is formed, the heat diffusion portion efficiently diffuses heat. The above effects can be exhibited.

As an example of the configuration of the heat diffusing unit, for example, a thermal conductivity such that the thermal conductivity in a plane parallel to the cooling surface of the Peltier module is larger than the thermal conductivity in a direction perpendicular to the cooling surface of the Peltier module. There is an example in which a substrate for fixing a semiconductor laser element is formed using a material having anisotropy. In this case, heat from the semiconductor laser element can be efficiently spread in the lateral direction. The same effect as the effect can be obtained.

Further, as another configuration example of the heat diffusion unit, for example, the bottom plate of the package to which the Peltier module is fixed is such that the heat conductivity in a plane parallel to the heating surface of the Peltier module is perpendicular to the heating surface of the Peltier module. In this case, the flow of heat discharged to the heat sink can be extended to the peripheral portion, and the effective heat resistance of the heat discharge path can be increased. Becomes smaller. As a result, the temperature difference between the insulating substrate on the heating side of the Peltier module and the heat sink is reduced, and the load on the Peltier module is reduced. As a result, a semiconductor laser module that can operate at higher temperatures and consumes less power can be manufactured. It becomes.

Further, a heat diffusion portion is formed in the Peltier module fixing region on the bottom plate of the package, a fiber reinforced composite material is used as the heat diffusion portion, and air permeability is provided outside the Peltier module fixing region. According to the present invention having the configuration in which the hermeticity-free portion is formed without air, similarly to the above, the flow of heat discharged to the heat sink is extended to the peripheral portion to reduce the effective thermal resistance of the heat discharge path. In addition, the semiconductor laser module which can operate at a higher temperature and consumes less power can be exhibited, and the airtightness of the package can be reliably maintained.

Further, according to the Peltier module of the present invention, since the heat absorption is larger in the peripheral portion than in the substantially central portion, when used in a semiconductor laser module, for example, the semiconductor laser The heat transfer based on the temperature gradient from the fixed substantially central portion to the peripheral portion of the element occurs more effectively.

As a result, the flow of the discharged heat can be extended to the peripheral portion without increasing the thickness of the semiconductor laser module, and the effective heat resistance of the heat discharge path is reduced.

Further, the temperature difference between the insulating substrate on the cooling side and the insulating substrate on the heating side of the Peltier module is reduced, the load on the Peltier module is reduced, and a semiconductor laser module that can operate at a higher temperature and consumes less power can be manufactured. Become.

[Brief description of the drawings]

FIG. 1 is a sectional view of a semiconductor laser module according to an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing an arrangement and a wiring pattern of a thermoelectric effect element of a Peltier module used in the semiconductor laser module according to the embodiment of the present invention, wherein FIG. (b) is a view of the cooling-side substrate viewed from the heating-side substrate.

FIGS. 3A and 3B are diagrams showing an arrangement and a wiring pattern of a thermoelectric effect element of a Peltier module used in a semiconductor laser module according to another embodiment of the present invention, and FIG. (B) is a view of the cooling-side substrate viewed from the heating-side substrate.

FIG. 4 is a wiring diagram of a thermoelectric effect element of a Peltier module used in a semiconductor laser module according to another embodiment of the present invention.

FIG. 5 is an explanatory view showing a structure for fixing a Peltier module to a bottom plate used in a semiconductor laser module according to another embodiment of the present invention.

FIG. 6 is a sectional view of a conventional semiconductor laser module.

7A and 7B are views showing a Peltier module used in a conventional semiconductor laser module, wherein FIG. 7A is a cross-sectional view of the Peltier module, FIG. 7B is a perspective view in which upper and lower insulating substrates are omitted, and FIG. () Is a wiring diagram of the thermoelectric effect element.

FIG. 8 is an explanatory diagram showing a method for manufacturing a Peltier module.

FIG. 9 is an explanatory diagram for explaining a thermal environment of the semiconductor laser module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Semiconductor laser module 11 Package 12 Peltier module 13 Semiconductor laser element 14 Thermistor 15 Lens 16 Substrate 17 Optical fiber 18 P-type thermoelectric conversion element 19 N-type thermoelectric conversion element 22 Peltier module 30 Fiber-reinforced composite material 50 Heat sink

Claims (8)

[Claims] 1. A semiconductor laser device, a substrate on which the semiconductor laser device is mounted, an optical fiber for receiving light emitted from the semiconductor laser device, and an optical fiber interposed between the semiconductor laser device and the optical fiber. Optical coupling means for optically coupling laser light emitted from the semiconductor laser element to the optical fiber, a Peltier module for cooling the substrate on which the semiconductor laser element is mounted, the semiconductor laser element, and the substrate A semiconductor laser module having a package for accommodating the Peltier module, wherein the semiconductor laser element is disposed above a substantially central portion of the Peltier module, and the heat absorption of the Peltier module is small in a substantially central portion; Semiconductor laser module characterized in that it is formed so as to be large in a portion . 2. A semiconductor laser comprising: a semiconductor laser element; a substrate on which the semiconductor laser element is mounted; a Peltier module for cooling the substrate; and a package containing the semiconductor laser element, the substrate, and the Peltier module. A module, wherein the substrate, the Peltier module, and a bottom plate of a package on which the Peltier module is mounted are formed, and at least a part of a heat exhaust path for exhausting heat from the semiconductor laser element includes the semiconductor. A semiconductor laser module, wherein a heat diffusion portion having a higher thermal conductivity of heat in a direction perpendicular to the direction from the laser element to the Peltier module is formed. 3. A heat diffusion portion is formed on a bottom plate of the package in a Peltier module fixing region, a fiber reinforced composite material is used as the heat diffusion portion, and air permeability is provided outside the Peltier module fixing region. 3. The semiconductor laser module according to claim 2, wherein a hermetic holding portion having no gap is formed. 4. A Peltier module includes a plurality of P-type and N-type thermoelectric conversion element pairs, and two ceramic plates sandwiching the plurality of thermoelectric conversion element pairs, wherein the plurality of thermoelectric conversion element pairs are ceramic plates. The semiconductor laser module according to any one of claims 1 to 3, wherein the peripheral portion is arranged more densely than the substantially central portion. 5. A Peltier module includes a plurality of P-type and N-type thermoelectric conversion element pairs, and two ceramic plates sandwiching the plurality of thermoelectric conversion element pairs. Thermoelectric conversion element pair comprises a first part electrically connected in series and a second part in which a plurality of thermoelectric conversion element pairs are connected in parallel, and a thermoelectric conversion element corresponding to the first part A pair is arranged on the periphery of the ceramic plate and a second
The semiconductor laser module according to any one of claims 1 to 4, wherein a thermoelectric conversion element pair corresponding to the portion (1) is disposed substantially at the center of the ceramic plate. 6. A Peltier module, wherein a heat absorption amount is small in a substantially central portion and large in a peripheral portion. 7. A plurality of P-type and N-type thermoelectric conversion element pairs, and two insulating layers sandwiching the plurality of thermoelectric conversion element pairs, wherein the plurality of thermoelectric conversion element pairs are peripherally located between the insulating layers. The Peltier module according to claim 7, wherein the parts are arranged more densely than a substantially central part. 8. A thermoelectric conversion element comprising: a plurality of P-type and N-type thermoelectric conversion element pairs; and two insulating layers sandwiching the plurality of thermoelectric conversion element pairs. The conversion element pair is composed of a first part electrically connected in series and a second part in which a plurality of thermoelectric conversion element pairs are connected in parallel, and a thermoelectric conversion element pair corresponding to the first part is provided. The Peltier module according to claim 7, wherein a thermoelectric conversion element pair corresponding to a second portion and disposed at a peripheral portion between the insulating layers is disposed at a substantially central portion between the insulating layer insulating layers.