JPH04243181A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser module in which a Peltier element scarcely deteriorates even if the temperature changes while the module is operated. CONSTITUTION:For example, in a semiconductor laser module having a Peltier element 2, a base secured onto the element 2 by welding, a chip carrier 6 secured onto the base 4, and a semiconductor laser chip 8 secured onto the carrier 6, at least a part of the base 4 where the chip carrier 6 is secured is thinner than the other part.

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.

[0002] In optical communication systems that have been put to practical use, a semiconductor laser is generally intensity-modulated with time-series current pulses, and this intensity-modulated light is transmitted to the receiving side via an optical fiber. In order to efficiently guide the light emitted from a semiconductor laser chip into an optical fiber, the light emitted from the chip is focused by a lens (in some cases, installed integrally with the optical fiber at the tip of the optical fiber). It is necessary to input it into the fiber. For this reason, on the transmitting side of an optical communication system, a semiconductor laser module is used in which a semiconductor laser chip and an end portion of an optical fiber are held in a predetermined positional relationship.

This type of semiconductor laser module is equipped with a Peltier element for cooling the semiconductor laser chip, and the semiconductor laser chip is fixed onto the Peltier element via a base and a chip carrier.

0004

2. Description of the Related Art Conventionally, as shown in FIG. 9, a Peltier element 2, a base 4 welded and fixed on the Peltier element 2,
A semiconductor laser module is known that includes a chip carrier 6 fixed on a base 4 mainly for heat dissipation, and a semiconductor laser chip 8 fixed on the chip carrier 6.

[0005] A Peltier element uses the Peltier effect, which releases or absorbs heat other than Joule heat, for purposes such as cooling, when current is passed through contacts of different types of conductors or semiconductors.
Structurally, it includes two parallel ceramic substrates 2a and 2b and a conductor or semiconductor 2c interposed between them.

The heat generated when the semiconductor laser chip 8 is driven is absorbed by the Peltier element 2 via the chip carrier 6 and the base 4 in accordance with the control current of the Peltier element 2, and this absorbed heat is It is released to the outside through a module housing (not shown). The light emitted from the semiconductor laser chip 8 is focused by a lens (not shown) fixed on the base 4, for example, and guided into an optical fiber (not shown).

[0007]

[Problems to be Solved by the Invention] Conventionally, in order to fix the base 4 made of, for example, a SUS material to a Peltier element, a Peltier element having a ceramic substrate with a metal land formed on the surface was used, and the base 4 was fixed to the Peltier element on the metal land. This was done by welding.

However, since the linear thermal expansion coefficients of the base and the ceramic substrate generally differ greatly, there is a problem in that when temperature changes are applied to the base and the ceramic substrate during use of the module, thermal stress acts on the base and the ceramic substrate, causing deterioration of the Peltier element. Ta. Specifically, the deterioration of the Peltier element is an increase in contact resistance due to deformation of the ceramic substrate 2a.

The present invention was created in view of the above points, and an object of the present invention is to provide a semiconductor laser module in which the Peltier element does not easily deteriorate even if temperature changes are applied during use of the module.

0010

[Means for solving the problem] The technical problem mentioned above is
This problem is solved by any one of the first to fifth configurations of the semiconductor laser module of the present invention.

FIG. 1 is a diagram illustrating the principle of a first configuration of a semiconductor laser module according to the present invention.

This semiconductor laser module includes a Peltier element 2, a base 4 welded and fixed on the Peltier element 2, a chip carrier 6 fixed on the base 4,
In a semiconductor laser module (hereinafter referred to as a "known module") comprising a semiconductor laser chip 8 fixed on the chip carrier 6, at least the part of the base 4 on which the chip carrier 6 is fixed is separated from other parts. It is constructed thinner than the

A second configuration of the semiconductor laser module of the present invention is a known module in which a notch is formed in the vicinity of the welded portion of the base.

A third configuration of the semiconductor laser module of the present invention is a known module in which a hole penetrating from the front surface to the back surface of the base is formed.

A fourth configuration of the semiconductor laser module of the present invention is a known module in which grooves are alternately formed on the front and back surfaces of the base.

A fifth configuration of the semiconductor laser module of the present invention is a known module in which a counterbore is formed in the vicinity of the welded portion of the base.

[0017]

[Operation] According to the first configuration of the present invention, at least the part of the base to which the chip carrier is fixed is made thinner than other parts, so that when a temperature change is applied during use of the module, the base and Peltier element Thermal stress generated in the base is absorbed by deformation of the base, making it difficult for the Peltier element to deteriorate.

According to the second or third configuration of the present invention, a notch is formed in the vicinity of the welded portion of the base or a hole is formed penetrating from the front surface to the back surface of the base, so that the cost is reduced compared to the conventional configuration. The base becomes easier to deform, and the Peltier element is less likely to deteriorate in the same way as in the first configuration.

According to the fourth aspect of the present invention, since the grooves are formed alternately on the front and back surfaces of the base, the base is easily deformed, and the Peltier element is similarly prevented from deteriorating.

According to the fifth aspect of the present invention, since the counterbore is formed near the welded portion of the base, the base is easily deformed, and the Peltier element is similarly prevented from deteriorating.

[0021]

[Examples] Examples of the present invention will be described below. FIG. 2 is a perspective view of a semiconductor laser module showing an embodiment of the present invention.

Reference numeral 10 denotes a module housing made of Kovar or the like, and a Peltier element 2 is provided on the inside bottom of this housing 10.
is fixed. 12 is an electronic circuit board housed within the housing 10. S welded and fixed on Peltier element 2
On the base 4 made of US material, there is a chip carrier 6 on which a semiconductor laser chip 8 is fixed, a first lens 14 for focusing the forward emitted light of the semiconductor laser chip 8, and a first lens 14 for focusing the forward emitted light of the semiconductor laser chip 8. A light receiving element 16 for monitoring rear emitted light is fixed.

Reference numeral 18 denotes a driver IC mounted on the electronic circuit board 12, and this IC is connected to the semiconductor laser chip 8. 20 is a lead terminal for electrically connecting the inside and outside of the casing 10, and 22 is an optical isolator fixed to the side surface of the casing 10. A fiber assembly 24 includes a second lens (not shown) and an optical fiber 26, and this assembly is fixed to the optical isolator 22 with its position adjusted. Semiconductor laser chip 8
The light emitted from the optical fiber is shaped into a desired beam shape by the first lens 14 and the second lens, and then guided into the optical fiber 26 .

FIG. 3 is a perspective view of a main part of a semiconductor laser module showing a first embodiment of the present invention, in which a Peltier element and parts mounted thereon (the first lens and the light receiving element are not shown) are shown. has been done. In this embodiment, the first configuration is adopted, and the base 4 includes thick portions 4a corresponding to the four corners thereof and thin portions 4b corresponding to the portions excluding the thick portions. The thin wall portion 4b of the base has eight notches 4 adjacent to the thick wall portion 4a from the outside to the inside of the thin wall portion.
c is formed, and the chip carrier 6 is mounted on the thin part 4b of the base so as not to overlap the notch 4c. The semiconductor laser chip 8 has gold deposited on the bottom surface of the chip and the top surface of the chip carrier 6, for example, Au/Sn.
It is fixed onto the chip carrier 6 using solder. The Peltier element 2 consists of two parallel ceramic substrates 2a, 2b and a conductor or semiconductor 2c interposed between them. Reference numeral 28 denotes a metal land made of a copper plate or the like fixed on the surface of the ceramic substrate 2a on which a semiconductor laser chip or the like is mounted.
It is welded and fixed onto the Peltier element 2 by laser welding.

According to this embodiment, since a plurality of notches 4c (8 in the figure) are formed in the thin portion 4b of the base, the base 4 becomes more easily deformed, and the Peltier element becomes more difficult to deteriorate.

FIG. 4 is a perspective view of a main part of a semiconductor laser module showing a second embodiment of the present invention, and the first configuration is also adopted in this embodiment. In this embodiment, a notch 4d is not formed in the thin part 4b of the base, but a notch 4d is formed in the thick part 4a of the base substantially parallel to the ceramic substrate 2a. Two notches 4d are formed in each thick part 4a of the base, and these two
The formation directions of the two cuts are perpendicular to each other.

According to this embodiment, the linear thermal expansion coefficient of the base and the ceramic substrate 2a are similar to the first embodiment.
Thermal stress caused by the difference in linear thermal expansion coefficients is absorbed by deforming the thick portion 4a of the base 4, so that the Peltier element 2 is less likely to deteriorate. In other words, since the ceramic substrate 2a is difficult to deform, undesired stress is less likely to be applied to the joint between the conductor or semiconductor 2c and the ceramic substrate 2a, and there is no fear that contact resistance will increase. In this embodiment, the directions of the cuts formed in the thick portion 4a of the base are perpendicular to each other in order to make it easier for the base 4 to deform uniformly in each direction.

FIG. 5 is a perspective view of a main part of a semiconductor laser module showing a third embodiment of the present invention, in which the second configuration is adopted. That is, the welded part of the base 4 (
The base 4 on the ceramic substrate 2a is formed by forming a notch 4e in the vicinity of the
This makes it easy to transform. In the illustrated example, two notches 4e are formed alternately on both sides of the chip carrier 6. Make a cut at a position like this 4
When the base 4 is deformed due to a temperature change, the positional deviation of the semiconductor laser chip 8 with respect to the module housing can be suppressed to a small value by forming the base 4, thereby making it possible to maintain high optical coupling efficiency.

FIG. 6 is a perspective view of a main part of a semiconductor laser module showing a fourth embodiment of the present invention, in which the third configuration is adopted. That is, by forming a hole 4f penetrating from the front surface to the back surface of the base 4 in a portion of the base 4 other than the portion to which the chip carrier 6 is fixed, deformation of the base 4 on the ceramic substrate 2a is facilitated. In the illustrated example, the holes 4f in the base are formed with the same shape and size on both sides of the chip carrier 6, so that when a temperature change is applied, the holes 4f in the base The laser chip 8 is less likely to be misaligned with respect to the module housing.

FIG. 7 is a perspective view of a main part of a semiconductor laser module showing a fifth embodiment of the present invention, and this embodiment employs the fourth configuration. That is, by forming a plurality of grooves 4g alternately on the front and back surfaces of the base 4, the base 4 can be easily deformed on the ceramic substrate 2a of the Peltier element. On the front side of the base 4, one groove 4g is formed on each side of the chip carrier 6 in parallel with the chip carrier 6, and on the back side of the base 4, two grooves are formed on each side so as to sandwich the groove on the front side. Groove 4
g. The shape, width, and gap of the grooves are set to be equal on both sides of the chip carrier 6, and this configuration makes it difficult for the chip carrier 8 to shift relative to the module housing when a temperature change is applied. .

FIG. 8 is a perspective view of a main part of a semiconductor laser module showing a sixth embodiment of the present invention, in which the fifth configuration is adopted. That is, by forming a counterbore 4h from the surface side of the base 4 near the welding part (indicated by a black dot) of the base 4 to the ceramic substrate 2a,
The substantial thickness of the base at the welded portion is reduced to facilitate deformation of the base 4 on the ceramic substrate 2a. The counterbore 4h is formed corresponding to each welding point. With this configuration as well, the base 4 is easily deformed when a temperature change is applied, so deterioration of the Peltier element 2 is prevented.

In each embodiment, the base 4 is fixed to the metal land (not shown in FIGS. 4 to 8) of the Peltier element by laser welding, so that the fixing work is easy and the fixing process is easy. The accompanying displacement of the base 4 with respect to the Peltier element 2 can be reduced. Further, in the case of the sixth embodiment, by forming the counterbore 4h in the base 4 in advance, it is easy to determine the position to be irradiated with the laser during laser welding, which is convenient in terms of work.

[0033]

[Effects of the Invention] As explained above, according to the present invention,
This has the effect that it is possible to provide a semiconductor laser module in which the Peltier element does not easily deteriorate even if a temperature change is applied during use of the module.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the principle of a first configuration of the present invention.

FIG. 2 is a perspective view of a semiconductor laser module showing an embodiment of the present invention.

FIG. 3 is a perspective view of a main part of a semiconductor laser module showing a first embodiment of the present invention.

FIG. 4 is a perspective view of a main part of a semiconductor laser module showing a second embodiment of the present invention.

FIG. 5 is a perspective view of a main part of a semiconductor laser module showing a third embodiment of the present invention.

FIG. 6 is a perspective view of a main part of a semiconductor laser module showing a fourth embodiment of the present invention.

FIG. 7 is a perspective view of a main part of a semiconductor laser module showing a fifth embodiment of the present invention.

FIG. 8 is a perspective view of a main part of a semiconductor laser module showing a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram of the prior art.

[Explanation of symbols]

2 Peltier element 4 Base 6 Chip carrier 8 Semiconductor laser chip

Claims (8)

[Claims] Claim 1: A Peltier element (2), a base (4) fixed by welding on the Peltier element (2), and a chip carrier (6) fixed on the base (4).
and a semiconductor laser chip (8) fixed on the chip carrier (6), in which at least the part of the base (4) to which the chip carrier (6) is fixed is separated from other parts. A semiconductor laser module characterized by being thinner than the previous model. 2. The semiconductor laser module according to claim 1, wherein a notch (4c) is formed in the thin portion of the base (4) from outside to inside. 3. The semiconductor laser module according to claim 1, wherein a notch (4d) is formed in the thick portion of the base (4). 4. A Peltier element (2), a base (4) fixed by welding on the Peltier element (2), and a chip carrier (6) fixed on the base (4).
and a semiconductor laser chip (8) fixed on the chip carrier (6), characterized in that a notch (4e) is formed in the vicinity of the welded part of the base (4). semiconductor laser module. 5. A Peltier element (2), a base (4) fixed by welding on the Peltier element (2), and a chip carrier (6) fixed on the base (4).
and a semiconductor laser chip (8) fixed on the chip carrier (6), characterized in that a hole (4f) penetrating from the front surface to the back surface of the base (4) is formed. Semiconductor laser module. 6. A Peltier element (2), a base (4) fixed by welding on the Peltier element (2), and a chip carrier (6) fixed on the base (4).
and a semiconductor laser chip (8) fixed on the chip carrier (6), characterized in that grooves (4g) are formed alternately on the front and back surfaces of the base (4). Semiconductor laser module. 7. A Peltier element (2), a base (4) fixed by welding on the Peltier element (2), and a chip carrier (6) fixed on the base (4).
and a semiconductor laser chip (8) fixed on the chip carrier (6), characterized in that a counterbore (4h) is formed near the welding part of the base (4). Semiconductor laser module. 8. The semiconductor laser module according to claim 1, wherein the base (4) is welded and fixed to the Peltier element (2) by laser welding.