JPH10326933A - High-frequency signal conductor for loading semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-frequency signal conductor for loading a semiconductor laser module, capable of transmitting high-frequency signals to the semiconductor laser module with little losses. SOLUTION: On a base 10 which is composed of a highly thermally conductive and low intrinsic electric resistance material, a signal transmission substrate 20 is fixed. The signal transmission substrate 20 is composed of a microstrip line 22 formed on a dielectric substrate 24. Also, to the base 10, a connector 30 is fixed. The semiconductor laser module 50 is loaded onto the base 10 and further, by using a press contact member 40, an electric signal lead 52 of the semiconductor module 50 is brought into press-contact with the microstrip line 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency signal conductor for mounting a light-emitting element module and transmitting a high-frequency electric signal to the module, and more particularly to a semiconductor laser module suitable for use in an optical communication system or the like. For high frequency signal conductors.

[0002]

2. Description of the Related Art An optical transmitter used in an optical communication system generally includes a control circuit board installed in a housing and a semiconductor light emitting element (laser) module driven by the control circuit board. . In an optical transmitter for transmitting a high-frequency optical signal, a high-frequency electric signal is
It is supplied to a semiconductor laser module or an external modulator connected outside the semiconductor laser module.

[0003] In recent years, the frequency of high-frequency signals used has been increased in accordance with the needs for high-speed and large-capacity transmission of optical communications. Recently, optical transmitters for transmitting high-frequency optical signals of 2.5 Gbit / s have been put into practical use. It is getting.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have developed a 10G communication system to meet the needs of higher speed and larger capacity optical communication.
We have developed an optical transmitter that transmits a high-frequency optical signal of bit / s. As described above, the basic configuration of the optical transmitter is the same as that of 2.5 Gbit / s, and the control circuit board installed in the housing and the semiconductor laser module driven by the control circuit board It is composed of For an optical transmitter having such a configuration, 10 Gbit /
When a high-frequency electric signal of s was applied to evaluate the characteristics of the optical transmitter, it was found that the electric signal was not effectively transmitted to the semiconductor laser in the semiconductor laser module. Since both the failure of the control circuit board and the failure of the semiconductor laser module can be considered as the cause of the ineffective transmission of the electric signal to the semiconductor laser, the control circuit board and the semiconductor laser module must be individually examined.

The inventors of the present application evaluated a semiconductor laser module alone by connecting a connector for inputting a high-frequency electric signal to an input terminal (lead) of the semiconductor laser module by soldering. As a result, it has been found that there is a problem that the loss of the high-frequency signal given to the semiconductor laser module is large and the signal amplitude of the high-frequency signal is deteriorated.

An object of the present invention is to provide a high-frequency signal conductor for mounting a semiconductor laser module, which can transmit a high-frequency signal with a small loss to the semiconductor laser module.

[0007]

Means for Solving the Problems In order to achieve the above object, the inventors of the present application have further studied the causes of the deterioration of the signal amplitude. It turned out that there was a problem with the soldered connection between the two. The characteristic impedance of a high-frequency electric signal fluctuates due to the influence of a parasitic capacitance and a parasitic inductance in a transmission path thereof. Therefore, reflection of a high-frequency electric signal occurs, and the frequency of a signal that can be transmitted is limited, and the loss of the electric signal occurs. . When the leads of the semiconductor laser module are fixed by soldering, the electric capacity (reactance) increases in proportion to the amount of solder in the soldered portion, and the characteristic impedance for high-frequency electric signals fluctuates. In particular, in transmitting a high-frequency electric signal in the gigahertz band, the parasitic capacitance of the soldered portion cannot be ignored, and a characteristic impedance mismatch caused by this occurs. The variation in the characteristic impedance causes an increase in the reflection loss of the high-frequency signal, and the signal amplitude of the high-frequency signal applied to the semiconductor laser module deteriorates. For this reason, the S / N ratio (signal / signal) of the high-frequency electric signal and the high-frequency optical signal output from the semiconductor laser module
It has been found that the noise ratio is degraded, which is an obstacle to accurate optical signal transmission.

(1) In order to achieve the above object, the present invention provides a base made of a material having high thermal conductivity and low specific electric resistance, a base fixed on the base and formed on a dielectric substrate. A signal transmission board having a microstrip line, and a connector fixed to the base and transmitting a high-frequency electric signal to the signal transmission board, and a semiconductor laser module is mounted on the base, whereby the semiconductor An electrical signal lead of the laser module is brought into mechanical contact with the microstrip line to be electrically connected. With this configuration, a high-frequency signal can be transmitted to the semiconductor laser module with a small loss.

(2) In the above (1), preferably,
Further, a pressure contact member is provided between the base and the base for pressing the electric signal lead of the semiconductor laser module and the microstrip line therebetween, and the contact pressure by the pressure contact member can be adjusted. With this configuration, the reproducibility when the semiconductor laser module is mounted can be improved.

(3) In the above (1), preferably,
Further, the base is provided with a radiation fin. With this configuration, the operation state of the semiconductor laser in the semiconductor laser module can be stabilized. (4) In the above (1), preferably, the base further includes a guide mechanism for fixing a semiconductor laser module on a surface on which the semiconductor laser module is mounted. With this configuration, the reproducibility of the mounting state of the semiconductor laser module can be improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
The configuration of the high-frequency signal conductor for mounting a semiconductor laser module according to one embodiment of the present invention will be described. FIG.
FIG. 2 is an exploded perspective view of a high-frequency signal conductor showing a state where the semiconductor laser module according to one embodiment of the present invention is mounted, and FIG. 2 is a high-frequency signal conductor on which the semiconductor laser module is mounted as shown in FIG. 3 is a partial vertical sectional view of FIG.

A signal transmission board 20 comprising a microstrip line 22 and a dielectric board 24 is mounted and fixed to the first convex portion 12 of the base 10 by a semi-permanent fixing method such as soldering or brazing. Base 1
On the surface of the base 10, the signal transmission board 20 is fitted, and the upper surface of the microstrip line 22 is formed on the base 10 on which the signal transmission board 20 is fitted. The height is the same as the upper surface of the first protrusion 12.

The base 10 ensures heat dissipation from the semiconductor laser module 50 mounted thereon, and prevents impedance mismatch due to stray electric capacitance with respect to the ground potential of the high-frequency electric signal.
It is made of copper or copper-tungsten alloy which is a material having high thermal conductivity and low specific electric resistance.

The dielectric substrate 24 is formed of a ceramic such as aluminum oxide. The microstrip line 22 is a metal plating film formed on the dielectric substrate 24. Micro strip line 22
Is formed, for example, from a Ni plating film formed on the dielectric substrate 24 and an Au plating film formed on the Ni plating film. An Au plating film is also formed on the back side of the dielectric substrate 24, that is, on the side opposite to the surface on which the microstrip lines 22 are formed, and on the surface in contact with the base 10. Since the base 10 is maintained at the ground potential, the Au plating film on the back side of the dielectric substrate 24 is also maintained at the ground potential.

Here, the characteristic impedance of the signal transmission board 20 is determined by the thickness of the dielectric board 24 and the width of the microstrip line 22. Therefore,
When the characteristic impedance of the signal transmission substrate 20 is matched with the high-frequency signal source, for example, 50Ω, the thickness of the dielectric substrate 24 is 0.5 mm, and the width of the microstrip line 22 is 0.5 mm. And In addition,
The thickness of the Ni plating film constituting the microstrip line 22 is 0.2 μm, and the thickness of the Au plating film is 2 μm.
And

A connector 30 is screwed into a screw hole formed in the second convex portion 14 of the base 10.
Fixed. The connector 30 is, for example, 40 Gbi
This is a low-reflection high-frequency connector having a reflection loss of 15 dB or more with respect to a high-frequency signal of t / s or less, for example, a 3.5 mm high-frequency connector standard called SMA. For this reason, it has compatibility with various power supplies such as a high-frequency signal source having an input / output interface conforming to the SMA, and electrical connection with control circuit devices and measuring devices. The end of the center pin of the connector 30 is soldered to the microstrip line 22. The end of the pin at the center of the connector 30 is spherical, and the gap formed between the spherical end and the flat microstrip line 22 is joined by solder.

The mounting screw holes 16a, 16b, 16c, 1 of the semiconductor laser module 50 are formed on the base 10 according to the package size of the semiconductor laser module 50.
6d is formed by processing. Semiconductor laser module 5
0 is placed on the base 10. Holes formed at four corners of the semiconductor laser module 50 and mounting screw holes 16a, 16b, 16c, 1 formed in the base 10.
The semiconductor laser module 50 is fixed on the base 10 by performing alignment of 6d and using screws (not shown). The electrical signal leads 52a,..., 52n are fixed to both side surfaces of the semiconductor laser module 50. The electric signal leads 52a,..., 52n are respectively provided with a semiconductor laser (not shown) arranged in the semiconductor laser module 50, a photodiode for monitoring light intensity, a thermistor for monitoring temperature, and a thermistor for monitoring temperature. It is connected to an electronic cooling element and the like. Here, the electric signal leads 52h,..., 52n fixed to one side surface of the semiconductor laser module 50 are arranged with terminals for inputting and outputting DC component electric signals. The electrical signal leads 52h,..., 52n are, for example, output terminals of a photodiode for monitoring light intensity and a thermistor for monitoring temperature, and are input terminals of a thermoelectric cooling element for adjusting temperature. Also, electrical signal leads 52a,..., 52g fixed to the other side surface of the semiconductor laser module 50.
The terminal to which the high-frequency component electric signal is input and the ground terminal are collectively arranged. Electrical signal lead 52c
Is an input terminal for a high-frequency signal. Electrical signal lead 5
2b, 52d, 52f, and 52g are ground terminals.
Note that the electrical signal leads 52a and 52e are not used.

The height of the first projection 12 is determined in accordance with the height of the electrical signal leads 52a,..., 52g. Therefore, the semiconductor laser module 50 is
The electrical signal lead 52c, which is an input terminal for a high-frequency signal, is in mechanical contact with the microstrip line 22 and is electrically conductive.

Further, in this embodiment, a press-contact member 40 having an L-shaped cross section is used. Pressing member 40
Is formed of an insulating material such as a glass epoxy composite material or an acrylic resin. The press contact member 40 is placed on the first protrusion 12 and the second protrusion 14. Two holes 40a and 40b formed in the press-contact member 40 and mounting screw holes 14 formed in the second convex portion of the base 10.
The press-contact member 40 is fixed on the base 10 using the screws (not shown) after the alignment with the positions a and b.
At this time, the lower surface 42 of the press contact member 40 is opposed to the upper surface of the first convex portion of the base 10, and between these two surfaces, the electrical signal leads 52a,. Since 52g is sandwiched, the electrical signal lead 52c, which is the input terminal of the high-frequency signal, and the microstrip line 22 are pressed against each other. Here, the pressing member 40 for pressing the contact portion between the high-frequency signal input lead 52c of the semiconductor laser module 50 and the microstrip line 22 has a structure in which the contact pressure can be adjusted by controlling the tightening torque of the mounting screw. I have. Also, electrical signal leads 52b, 5 for the ground terminal are provided.
2d, 52f, and 52g are the first convex portions 12 of the base 10.
And the electrical signal leads 52b, 52d,
52f, 52g and the base 10 are electrically connected. Since the base 10 is maintained at the ground potential as described above, the electrical signal leads 52b, 52d, 52f,
52 g can be the ground potential.

Next, the press-contact state between the electrical signal lead of the semiconductor laser module and the microstrip line will be described with reference to FIG. A signal transmission substrate 20 including a microstrip line 22 and a dielectric substrate 24 is fixed to the first convex portion 12 of the base 10. The connector 30 is screwed and fixed in a screw hole formed in the second convex portion 14 of the base 10. The end of the pin 32 at the center of the connector 30 is soldered to the microstrip line 22.

The semiconductor laser module 50 has a base 1
0, is positioned on a mounting screw hole formed in the base 10, and is fixed by a screw. When the semiconductor laser module 50 is fixed on the base 10, the electrical signal lead 52c, which is an input terminal for a high-frequency signal, comes into mechanical contact with the microstrip line 22 and becomes electrically conductive.

Further, the press-contact member 40 having an L-shaped cross section.
Is mounted on the first convex portion 12 and the second convex portion 14, and is fixed on the base 10 by screws. Therefore, the electrical signal leads 5 of the semiconductor laser module 50
2 c is sandwiched between the pressure contact member 40 and the first convex portion 12 of the base 10, and the electrical signal lead 52 c, which is an input terminal for a high-frequency signal, and the microstrip line 22
It is pressed.

In order to evaluate the semiconductor laser module 50, the semiconductor laser module 50 is mounted on the base 10 and fixed with screws. Further, by fixing the pressure contact member 40 on the base 10, the electrical signal lead 52c and the microstrip line 22 are pressed against each other.

By connecting the connector of the cable connected to the high-frequency source to the connector 30, the high-frequency electric signal is transmitted to the signal transmission board 20 and the electric signal leads 52c.
To the semiconductor laser in the semiconductor laser module 50.

The microstrip line 22 of the signal transmission board 20 is mechanically connected to the electrical signal lead 52c, and is not soldered. Therefore, the characteristics are affected by the influence of the parasitic capacitance and the parasitic inductance due to the soldered connection. Since the impedance does not fluctuate and the reflection of the high-frequency electric signal can be reduced, the frequency limitation of the signal that can be transmitted and the loss of the electric signal do not occur. That is, a high-frequency electric signal in the gigahertz band can be transmitted with very little reflection loss.

When the evaluation of the semiconductor laser module 50 is completed and the semiconductor laser module 50 is removed,
It is only necessary to remove the screw for fixing the press-contact member 40 and the screw for fixing the semiconductor laser module 50, so that the removal is easier than in the case of solder connection. Similarly, the mounting of the semiconductor laser module 50 is also facilitated.

When the solder connection is performed, the mounting state (solder amount, solder contact state, etc.) of the soldering part changes as the semiconductor laser module 50 is mounted and removed, so that the impedance mismatch at the mounting part. However, such an inconvenience does not occur in the case of attachment using the press contact member 40.

Examples of mounting and dismounting of the semiconductor laser module include, for example, replacement when the semiconductor laser module is deteriorated or damaged, a characteristic test on the semiconductor laser module alone, and a control circuit in the initial adjustment stage. And adjusting the characteristics by changing the combination of the semiconductor laser module and the semiconductor laser module. Since both the semiconductor laser and the laser driving IC (integrated circuit) are semiconductor elements, their characteristics are inevitable. However, when evaluating the characteristics of a single semiconductor laser module, and when combining a control circuit and a semiconductor laser module. In the work for optimizing the work, the work of attaching to and removing from the substrate is easy, and the repetition of the work is high.

In particular, the high frequency signal input lead 52c of the semiconductor laser module 50 and the microstrip line 2
The contact pressure by the pressure contact member 40 that presses the contact portion with 2 is
The reproducibility can be improved by controlling with the tightening torque of the mounting screw.

As described above, according to the present embodiment, it is possible to transmit a high-frequency signal to the semiconductor laser module with a small loss.

Also, when the semiconductor laser module is electrically connected to various power sources such as a high-frequency signal source, control circuit devices and measuring instruments, the semiconductor laser module is more electrically connected than when the electrical connection is made by soldering. The attachment and detachment of the laser module can be easily performed, and the reproducibility of the connection state accompanying the attachment and detachment is improved.

The input part of the high-frequency electric signal to the high-frequency signal conductor is a low-reflection high-frequency connector conforming to the standard, and the characteristic impedance of the dielectric substrate on which the microstrip line is formed is matched with the high-frequency signal source. This makes it possible to minimize the transmission loss of high-frequency electric signals and to cope with connections to various power supplies, control circuit devices, measuring devices, and the like. Therefore, mounting and dismounting can be facilitated when a large number of characteristics of the semiconductor laser module alone are evaluated (for example, a characteristic test process at a production stage) or when the semiconductor laser module is frequently replaced and evaluated. In addition, reproducibility of the mounting state can be secured.

Next, the configuration of a high-frequency signal conductor for mounting a semiconductor laser module according to another embodiment of the present invention will be described with reference to FIG. FIG. 3 is a perspective view of a high-frequency signal conductor on which a semiconductor laser module according to another embodiment of the present invention is mounted. The same reference numerals as those in FIG. 1 indicate the same parts.

A signal transmission substrate 20 including a microstrip line 22 and a dielectric substrate 24 is fixed to the first convex portion 12 of the base 10A. A screw hole formed in the second projection 14 of the base 10A has a connector 3
0 is screwed in and fixed. The end of the center pin of the connector 30 is soldered to the microstrip line 22.

Further, in this embodiment, the base 1
0A, on the mounting position of the semiconductor laser module,
Guide pins 18a, 18b, 18 for alignment guidance
c, 18d are provided. Guide pins 18a to 18
Since the tip of d has a tapered shape, the semiconductor laser module can be easily positioned by engaging the holes formed at the four corners of the semiconductor laser module with the guide pins 18a to 18d. It becomes possible. Therefore, the high-frequency signal input lead of the semiconductor laser module matches the microstrip line 22 with good reproducibility. This makes it possible to improve the reproducibility of the contact position between the high-frequency signal input lead of the semiconductor laser module and the microstrip line 22 during attachment and detachment.

When the semiconductor laser module is positioned on the base 10A, the press-contact member is placed on the first convex portion 12 and the second convex portion 14 as described with reference to FIG. It is fixed on the base 10A by screws. Therefore, the electrical signal lead of the semiconductor laser module is sandwiched between the pressure contact member and the first convex portion 12 of the base 10A, and the electrical signal lead, which is an input terminal for a high-frequency signal, and the microstrip line 22 are pressed against each other. Is done.

Further, in this embodiment, the base 1
0A is on the back side of the mounting surface of the semiconductor laser module,
The radiation fin 19 is formed. The semiconductor laser module has a temperature control function to keep the operating state of the semiconductor laser constant inside, and the bottom surface (bottom flange) of the semiconductor laser module is a heat radiation surface.
The bottom (bottom flange) of this semiconductor laser module
In order to enhance the heat radiation effect of the base 10A that comes in contact with the fin, a heat radiation fin 19 is provided. Thereby, the thermal load on the temperature control function of the semiconductor laser module can be reduced, and the stability of the operation state of the semiconductor laser can be ensured.

Although the radiation fin 19 has been described as being integrally formed with the base 10A, the heat radiation fin 19 is formed on the back side of the base 10 having the structure shown in FIG. By joining the radiating fins, it is possible to make the structure more inexpensive.

As described above, according to the present embodiment, it is possible to transmit a high-frequency signal to the semiconductor laser module with a small loss.

Further, the repeatability of the contact position between the high frequency signal input lead of the semiconductor laser module and the microstrip line can be improved.

Further, by providing a radiation fin,
The stability of the operation state of the semiconductor laser can be ensured.

[0042]

As described above, according to the present invention,
It is possible to transmit a high-frequency signal to the semiconductor laser module with a small loss.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a high-frequency signal conductor showing a state in which a semiconductor laser module according to an embodiment of the present invention is mounted.

FIG. 2 is a partial longitudinal sectional view of a high-frequency signal conductor on which the semiconductor laser module is mounted as shown in FIG.

FIG. 3 is a perspective view of a high-frequency signal conductor on which a semiconductor laser module according to another embodiment of the present invention is mounted.

[Explanation of symbols]

 10, 10A Base 12 First protrusion 14 Second protrusion 18 Guide pin 19 Heat radiation fin 20 Signal transmission board 22 Microstrip line 24 Dielectric substrate 30 High frequency connector 40 Pressure contact Member 50: Semiconductor laser module 52: Electric signal lead

Claims (4)

[Claims] 1. A base made of a material having high thermal conductivity and low specific electric resistance, a signal transmission substrate fixed on the base and having a microstrip line formed on a dielectric substrate, and fixed to the base. And a connector for transmitting a high-frequency electric signal to the signal transmission board. By mounting the semiconductor laser module on the base, an electric signal lead of the semiconductor laser module is mechanically connected to the microstrip line. A high-frequency signal conductor for mounting a semiconductor laser module, wherein said high-frequency signal conductor is brought into contact and electrically connected. 2. The high-frequency signal conductor for mounting a semiconductor laser module according to claim 1, further comprising a press-contact member for pressing said electric signal lead of said semiconductor laser module and said microstrip line between said base and said base. A high-frequency signal conductor for mounting a semiconductor laser module, wherein a contact pressure of the pressure contact member is adjustable. 3. The high-frequency signal conductor for mounting a semiconductor laser module according to claim 1, wherein said base further comprises a radiation fin. 4. The high-frequency signal conductor for mounting a semiconductor laser module according to claim 1, further comprising a guide mechanism for fixing a position of the semiconductor laser module on a surface on which the semiconductor laser module is mounted. A high-frequency signal conductor for mounting a semiconductor laser module.