JPH05150146A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To reduce the optical axis deviation of optical components which constitute an optical coupling system, to facilitate wiring operation, and to reduce the overall size. CONSTITUTION:The projection light of a semiconductor laser 2 is made incident on an optical fiber 4 thorugh a lens body 3 and this projection state is monitored by a photodetecting element 5. Those semiconductor laser 2, lens body 3, photodetecting element 3, etc., are arranged and fixed on a substrate 6. Those parts 6a and 6b are formed on the substrate 6 on both side parts which are parallel to an optical axis and the deformation of the substrate due to the heat radiation of the semiconductor laser 2 is reducible in the direction of the optical axis. The substrate 6 is cooled by a lower electronic cooling element 7.

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 optical measurement.

[0002]

2. Description of the Related Art FIGS. 5A and 5B are a side sectional view and a plan sectional view of a semiconductor laser module (hereinafter abbreviated as LD module) used in optical communication and the like. An LD (semiconductor laser) 3 as a light emitting element is provided in the housing 31.
2 is provided, and the light emitted from this LD 32 is the lens body 3.
It is incident on the end portion of the optical fiber 34 via the light source 3. A ferrule 34a is provided at the end of the optical fiber 34. A light receiving element 35 for monitoring (hereinafter abbreviated as PD) is provided on the back of the LD 32, and an optical coupling system including the LD 32, the lens body 33, the optical fiber 34, and the light receiving element 35 is an airtight casing. It is built into the body 31. The optical coupling system excluding the optical fiber 34 is mounted on a single substrate 36 as shown in the figure, so that the mounting can be facilitated and stability over time can be obtained after fixing each optical component. ing.

By the way, since the LD 32 generates heat at the same time as infrared light emission, sufficient heat radiation is required. Therefore, the LD 32 is held and fixed to the housing 31 via the electronic cooling element 37 for cooling the LD 32 and a heat radiation block (not shown). Here, when the heat radiation of the LD 32 is not sufficient, the oscillation wavelength of the LD 32 shifts, the output deteriorates, and the life is shortened.

On the substrate 36, the LD among the optical components is used.
32, a relay terminal 38 of the PD 35 is provided, and each optical component is connected to the lead terminal 40 via the relay terminal 38 and the gold wire 39 to form a predetermined electric circuit. Further, the electronic cooling element 37 includes a relay terminal 38,
It is wired directly to the lead terminal 40 without passing through the gold wire 39.

[0005]

A problem with the reliability of the LD module is the misalignment of the optical axis, which significantly reduces the optical output. As a factor of the optical axis shift, each optical component constituting the optical coupling system, the mismatch of material constants such as the linear expansion coefficient of the substrate, and each optical component due to thermal stress caused by temperature change,
There is a deformation of the substrate and their joints. Therefore, in selecting each optical component, substrate, etc. constituting the optical coupling system, it is necessary to suppress the thermal stress by considering the heat radiation property, the bonding property, the workability, etc., while minimizing the difference in the material constants.
In addition, it is impossible to completely remove the deformation due to the uneven temperature distribution on the substrate 36 and the subtle difference in the material constants.

Therefore, in the conventional LD module,
The thickness of the substrate 36 is increased to increase the rigidity against deformation to reduce the optical axis shift, but when the substrate 36 is thick, the upper end position of each optical component becomes high. In addition, PD35
Since the wiring of the gold wire 39 to the terminals of the housing 3 is performed in the upper space of the housing 31, as shown in the drawing, the housing 3
A predetermined gap S had to be provided so that the gold wire 39 did not come into contact with the lid 31a of No. 1 to cause a short circuit. This gap S also causes the height of the housing 31 to increase. Therefore, the conventional LD module has a high housing 31 and a large volume.

By the way, the recent environment for mounting LD modules is high-density mounting on an array of printed boards such as a board for mounting a large computer and mounting on transportation equipment such as aircraft and automobiles, thus saving space. In order to meet this requirement, downsizing of LD modules is becoming an essential condition. In this respect, the conventional LD module is large in size and cannot be accommodated, and the LD module cannot be mounted on various device substrates or the like.

Thus, the heat capacity of the mounted parts and the housing 31
When the volume of the electronic cooling element 37 becomes large, the capacity of the electronic cooling element 37 must be improved in order to control the temperature according to the change of the external environment temperature from the viewpoint of thermal design. Therefore, the electronic cooling element 3
Although it is sufficient to increase the number of Peltier elements that configure 7, the electronic cooling element 37 becomes larger and the operating power increases.

The present invention has been made in view of the above problems, and does not cause an optical axis shift due to strength deterioration of each optical component, a substrate or the like which constitutes an optical coupling system or a restriction of wiring work. It is an object of the present invention to provide a semiconductor laser module that can be downsized and that is easy to radiate heat and advantageous in terms of heat radiation design.

[0010]

In order to achieve the above object, the semiconductor laser module of the present invention is characterized in that, in claim 1, the semiconductor laser 2 that generates heat with the emission of light and the emitted light of the semiconductor laser 2 are provided. Optical fiber 4 for transmission
A lens body 3 provided between the optical axes of the semiconductor laser 2 and the optical fiber 4 for condensing the light, and a light receiving element 5 for monitoring the optical output of the emitted light from the semiconductor laser 2. The semiconductor laser 2, the lens body 3, and the light receiving element 5
And a substrate 6 having thick portions 6a and 6b each having a predetermined thickness on both sides parallel to the optical axis, and mounted on the substrate to control cooling of the electronic cooling element. It is characterized by including a thermistor 21 for doing so and a casing 1 for accommodating these components.

Further, as in claim 2, a wiring board 15 may be provided, which is stacked on the substrate 6 and has a predetermined wiring pattern 16 formed thereon, and on which at least the light receiving element 5 is arranged. ..

Further, as described in claim 3, a groove portion 1b having a predetermined depth L1 is formed in the bottom portion of the housing 1 for accommodating the respective components, and a part of the electronic cooling element 7 is loosely fitted in the groove portion 1b. It may be a structure that does.

[0013]

The emitted light from the semiconductor laser 2 enters the optical fiber 4 through the lens body 3. The semiconductor laser 2 emits light and radiates heat to the substrate 6, but the substrate 6 is provided with thick portions 6a and 6b of a predetermined thickness on both sides parallel to the optical axis. Becomes higher,
The optical axis shift can be reduced without the substrate 6 being deformed in the optical axis direction. Further, by using the wiring board 15, the light receiving element 5 which is an active body among the components forming the optical coupling system has a part of its wiring printed on the printed pattern 1.
6, the wiring can be eliminated, and therefore the height can be reduced without requiring the space for wiring. Further, a groove 1b is formed on the bottom of the housing 1, and a part of the electronic cooling element 7 is loosely fitted in the groove 1b, so that the height of each component mounted on the electronic cooling element 7 can be reduced. Groove 1b
The depth can be lowered, and the entire device can be downsized. Also,
By loosely fitting a part of the electronic cooling element in the groove formed in the bottom of the housing 1, it is only necessary to mainly adjust the optical axis in the optical axis direction, and workability is improved.

[0014]

1 (a) and 1 (b) are respectively a side sectional view and a plan sectional view of a semiconductor laser module of the present invention,
FIG. 1C is a sectional view taken along the line AA of FIG. An upper portion of the housing 1 is opened, and a lid 1a is detachably provided in this opening. The end of the optical fiber 4 having the ferrule 4a is fixed to one end of the housing 1. Specifically, the optical fiber 4 is fixed by the holder 4b, but the optical fiber 4 may be detachably attached to the housing 1 by using a connector. In addition, in the lower part of the housing 1,
A groove 1b having a predetermined depth L1 and a predetermined width L2 is formed parallel to the optical axis direction.

Lead terminals 20 are provided on both sides of the housing 1 to electrically connect the optical components provided in the housing 1 to the outside. And this case 1
Nitrogen gas or an inert gas is enclosed in the inside of the to keep the airtightness. A part of the heat dissipation surface 7a of the electronic cooling element 7 composed of a Peltier element is loosely fitted and fixed in the groove portion 1b. The electronic cooling element 7 radiates the heat of a part of the heat absorbing surface 7b to the housing 1 side via the heat radiating surface 7a.

On the heat absorbing surface 7b of the electronic cooling element 7, a substrate 6 formed to have a predetermined thickness and a thin thickness is fixed. The substrate 6 is generally formed of a material having a good heat dissipation effect such as copper tungsten. 2A and 2B are views showing the substrate 6, where FIG. 2A is a plan view, FIG. 2B is a rear view, FIG. 2C is a side view, and FIG. 2D is a cross section taken along line BB in FIG. Figure,
(E) is a cross-sectional view taken along the line CC of FIG.
FIG. 7 is a sectional view taken along line D-D in FIG. 2 (b),
As shown in (e), thick-walled portions 6a and 6b having a predetermined thickness are formed on the lower portions of both sides of the substrate 6, respectively. The thick portions 6a and 6b are provided on both sides of the substrate 6 corresponding to the width of the heat absorption surface 7b of the electronic cooling element 7, and are oriented in the optical axis direction.

Further, as shown in FIGS. 2 (a) and 2 (f), the thick portions 6 having a predetermined thickness are formed on the upper portions of both sides of the substrate 6, respectively.
aa and 6ba are provided. Furthermore, as shown in FIG.
As shown in (c), (d), (e) and (f), the fixing portion 6 having the same height as the thick portions 6aa and 6ba is provided at the end of the substrate 6.
c is provided. The PD 5 is placed on the fixing portion 6c via a wiring board 15 described later. Therefore, as shown in FIG. 1C, the heat absorption surface 7 of the electronic cooling element 7 is
A substrate 6 is placed on the surface b, and thick portions 6a, 6b, 6aa, 6ba are provided on both sides parallel to the optical axis. In addition, the thick portion 6 is provided only on the lower portion of the substrate 6.
a and 6b are provided, and the thick parts 6aa and 6b are provided on the upper part.
It may be a flat surface excluding a and the fixing portion 6c.

On this substrate 6, a wiring substrate 15 made of a material having a small thermal resistance such as alumina ceramics is fixed. FIG. 3 is a plan view showing the wiring board 15.
As shown in the figure, the wiring board 15 is formed in a substantially U-shape in plan view, and the protruding portions 15a, 15 that are continuous at the upper positions of the thick portions 6aa, 6ba and the fixed portion 6c of the substrate 6 are formed.
It has a shape having an opening b at the center. Then, the wiring patterns 16a and 16b are formed on the front surface 15c, and the entire back surface is subjected to a metallizing treatment so that it can be soldered to the substrate 6.

As shown in FIG. 1, a wiring board 15 is provided on the board 6, and the back surface of the wiring board 15 is soldered and fixed on the board 6. On the substrate 6, the LD 2 is arranged in the central portion as a light emitting element. This LD2
Are fixed on the chip carrier 2a. Also, LD2
And a lens body 3 is provided between the ends of the optical fiber 4,
An optical coupling system is formed. The emitted light of the LD 2 is incident on the end portion of the optical fiber 4 via the lens body 3.

The lens body 3 includes an abutting block 3a provided in advance on the substrate 6, and the abutting block 3a.
It is composed of a lens holder 3b which is positioned by abutting on a. As shown in FIG. 1, the butting block 3a is formed by fixing two pillars on the substrate 6. Lens holder 3b
Has a cylindrical shape, holds the lens 3c therein, and has abutting portions 3d formed on both sides. For this lens 3c,
A spherical lens, a Selfoc lens, etc. are used. By abutting the abutting portion 3d of the lens holder 3b against the abutting block 3a, the position of the lens 3c in the optical axis direction is automatically positioned. After that, the lens holder 3b is fixed to the butting block 3a by finely adjusting the vertical and horizontal directions orthogonal to the optical axis with a jig or the like.

On the surface 15c of the wiring board 15, a PD 5 for monitoring the LD2 is arranged and fixed. This P
The terminal of D5 is directed downward, and is soldered and electrically connected and fixed at one end portion 16aa of the wiring pattern 16a at this fixing position. A relay terminal 8 for the LD 2 is provided on the substrate 6, and the LD 2 is connected to the lead terminal 20 via the relay terminal 8 and the gold wire 9. Further, the electronic cooling element 7 and the thermistor 21 are directly connected to the lead terminal 20. And a predetermined electric circuit is configured. further,
The other end 16ab of the wiring pattern 16 of the wiring board 15
Is also connected to the lead terminal 20 via the gold wire 9. Then, the inside of the housing 1 is hermetically sealed by joining the lid 1a with seam welding in a state where nitrogen gas or an inert gas is enclosed.

Next, the operation of the above configuration will be described. In the state where the above-mentioned components are assembled, the electronic cooling element 7
A part (heat dissipation surface 7a) of the housing 1 has a predetermined depth L1.
It is loosely fitted in the groove portion 1b. Since the groove portion 1b is formed with a diameter (L2) substantially the same as the width of the electronic cooling element 7, all the optical coupling systems having the electronic cooling element 7 at the bottom are
Since the clearance in the direction orthogonal to the optical axis direction is small in the groove portion 1b, the adjustment can be easily performed, and also the slide adjustment can be performed in the optical axis direction when, for example, an optical isotope, a filter, etc. are arranged and housed. .. As described above, since the electronic cooling element 7 is loosely fitted in the groove 1b and the substrate 6 is formed thin, the overall height can be reduced. In addition, since the terminals of the PD 5 are directly joined to the wiring pattern 16 on the wiring board 15 without using gold wires, the height of the PD 5 portion can be increased without taking the space height required for electrical connection of the PD 5. Can be lowered. As a result, the overall height can be reduced, the height of the housing 1 can be reduced, and the size can be reduced.

The light emitted from the LD 2 is incident on the end of the optical fiber 4 via the lens body 3. Also, L
The optical output of the emitted light from D2 is monitored by PD5. The LD2 radiates heat to the substrate 6 due to the heat generated by the light emitted from the LD2. The substrate 6 is formed thin and deforms the substrate 6. However, since the substrate 6 has thick portions 6a and 6b each having a predetermined thickness on both sides thereof, and the thick portions 6a and 6b are formed parallel to the optical axis direction, Deformation due to thermal stress in the axial direction can be reduced. Therefore, even if the substrate 6 is thin, a predetermined rigidity can be obtained in the optical axis direction. In addition,
The heat of the substrate 6 is absorbed by the electronic cooling element 7, so that the deformation can be prevented at the same time.

Further, since a predetermined wiring pattern 16 is formed on the wiring board 15, the PD 5 is electrically connected,
That is, in the wiring between the PD 5 and the lead terminal 20, the wiring pattern 16 is extended to the vicinity of the lead terminal 20, so that the gold wire 9 can be made as short as possible, and the wiring inside the housing 1 can be routed. Can be reduced. The wiring pattern 16 of the wiring board 15 is formed in a pattern corresponding to the lead terminals 20 required by the user, and can be easily changed.

The lens body 3 in the above embodiment is
As shown in the perspective view of FIG. 4, an abutment block 3a fixed in advance on the substrate 6 is formed in a rectangular shape having a cylindrical fitting portion 3aa therein, and the lens holder 3b is formed in the fitting portion 3a.
It may be configured by having a cylindrical portion 3ba having a diameter corresponding to a, and the lens 3c is automatically positioned in the optical axis direction only by abutting the lens holder 3b on the abutting block 3a. Can be done.

Further, the groove 1b has a structure in which only a part of the electronic cooling element 7 is loosely fitted. However, in the groove 1b, another component parallel to the electronic cooling element 7 such as an optical isolator. It is possible to arrange and house a filter and the like at the same time.

In the semiconductor laser module according to the above-mentioned embodiment, the light emitting source for making the light emitted from the LD 2 incident on the optical fiber 4 is described as an example. However, an LED may be used in place of the LD as a light emitting element, and an arrangement location of the LD The above configuration may be applied to the light receiving module in which the PD is arranged, and in this case as well, the height of the entire module can be reduced, and, of course, the same effect as the above embodiment can be obtained.

[0028]

According to the first aspect of the invention, since the thick portions are provided on both sides of the substrate in parallel with the optical axis direction, the bending stress in the optical axis direction is the same as that of the conventional substrate and the substrate thickness is Can be made thin and is strong against deformation and does not take height. At the same time, since the heat capacity of the substrate is reduced, the power consumption required for cooling the electronic cooling element can be reduced.

According to the second aspect, the wiring board on which the predetermined wiring pattern is formed allows the wire wiring of the active body requiring the electric wiring in the end portion of the wiring pattern in the optical coupling system. The wiring work can be facilitated, and it is not necessary to consider a wiring short-circuit during the wiring work of a bare wire such as a gold wire, so that workability can be improved and assembly time can be shortened. Further, since the wiring substrate is provided on the thin substrate, the substrate can be reinforced and the deformation can be prevented.

According to the third aspect of the invention, since the groove is provided in the bottom of the housing, the total height of the components forming the electronic cooling element and the optical coupling system provided on the groove can be calculated as follows. The module can be made low, the module as a whole can be made compact, and this module can be installed on a printed circuit board in a space-saving manner. Further, since the groove portion and the electronic cooling element are loosely fitted, the adjustment in the optical axis direction may be mainly performed, and the assembling workability is improved.

[Brief description of drawings]

FIG. 1A is a side sectional view showing a semiconductor laser module of the present invention. (B) is a plane sectional view of the module.
(C) is the sectional view on the AA line of the same figure (b).

FIG. 2A is a plan view showing a substrate. (B) is a rear view of the substrate. (C) is the same side view. (D) is the BB line sectional view of the same figure (a). (E) is the CC sectional view taken on the line. (F) is the DD sectional view taken on the line.

FIG. 3 is a plan view showing a wiring board.

FIG. 4 is a perspective view showing a lens body according to another configuration example.

FIG. 5A is a side sectional view showing a semiconductor laser module. (B) is the same plane sectional view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing | casing 1b ... Groove part, 2 ... Semiconductor laser, 3 ... Lens body, 3a ... Abutting block, 3b ... Lens holder, 3
c ... Lens, 4 ... Optical fiber, 5 ... Light receiving element, 6 ... Substrate, 6a, 6b ... Thick portion, 7 ... Electronic cooling element, 8 ... Relay terminal, 9 ... Gold wire, 20 ... Lead terminal.

Claims (3)

[Claims] 1. A semiconductor laser (2) which generates heat as light is emitted; an optical fiber (4) for transmitting light emitted from the semiconductor laser; and an optical axis between the semiconductor laser and the optical fiber. A lens body (3) provided for condensing the emitted light; a light receiving element (5) for monitoring the light output of the emitted light from the semiconductor laser; and the semiconductor laser, the lens body and the light receiving element above the light receiving element. A substrate (6) on which an element is mounted, and thick portions (6a, 6b) having a predetermined thickness are formed on both sides parallel to the optical axis; and a substrate (6) provided below the substrate, An electronic cooling element (7) for cooling the heated semiconductor laser; a thermistor (21) mounted on the upper part of the substrate for controlling the cooling of the electronic cooling element; and a housing containing these components. Characterized by consisting of a body (1) Semiconductor laser module. 2. A wiring board () on which a predetermined wiring pattern (16) is formed, which is stacked on the substrate (6) and in which at least the light receiving element (5) is arranged. 15. The semiconductor laser module according to claim 1, further comprising 15). 3. A predetermined depth (L) at the bottom of the housing (1).
The semiconductor laser module according to claim 1, wherein the groove portion (1b) of 1) is formed, and a part of the electronic cooling element (7) is loosely fitted in the groove portion.