JP2616469B2 - Semiconductor laser module - Google Patents

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 having a semiconductor laser used in an optical fiber transmission system and the like, and more particularly to a semiconductor laser module suitable for a case having a modulation frequency band of 20 GHz or more.

[0002]

2. Description of the Related Art Semiconductor laser modules are used to convert electric signals into optical signals in, for example, an optical fiber transmission system. A semiconductor laser and a semiconductor laser drive circuit are arranged in the semiconductor laser module, and a modulated signal light can be obtained by driving the semiconductor laser with a predetermined electric signal.

FIG. 3 shows an example of a conventionally proposed semiconductor laser module. For example, JP-A-62-2
In such a semiconductor laser module disclosed in JP-A-205683 and JP-A-4-101484, a carrier 12 made of a substrate or the like is arranged slightly off to the right of the center of the module package 11 in the drawing.
A semiconductor laser 13 is disposed thereon. Laser light output from the semiconductor laser 13 is condensed by a lens 14 and coupled to an optical fiber 15 whose axis coincides with its optical axis. Further, the microstrip line 17 shared with one of the external terminals of the module package 11 and the semiconductor laser 13 are connected by a bonding wire 18, and a modulation signal 19 supplied from a modulation circuit (not shown) allows the semiconductor laser 13 to be driven. Modulation is performed.

FIG. 1 shows a module package 1
The other external terminals implanted in the device 1 and other circuit portions in the module package 11 connected to these external terminals are not shown in order to avoid complexity.

In such a conventional semiconductor laser module, the microstrip line 17 and the semiconductor laser 13
The microstrip line 17 is arranged close to the side wall of the package on which the optical fiber 15 is attached and the lens 14 in such a manner that the optical fiber 15 is attached to the lens 14. For this reason, there has been a problem that wire bonding is difficult. Also, the module package 11
In this figure, the pin arrangement cannot be changed so that the modulation signal is applied from an external terminal (not shown) arranged at a position closer to the left side, and there is a problem that the degree of freedom in design is small.

FIG. 4 shows a structure of another semiconductor laser module proposed to solve such a problem. The same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. Also in this figure, illustration of the external terminals and parts of the module package 11 not related to the present invention are omitted.

The semiconductor laser module shown in FIG. 4 is disclosed, for example, in JP-A-5-110210. In this module, a carrier 21 is arranged at a substantially central position in the module package 11. A first microstrip line 22 is formed on the surface of the carrier 21 as a transmission path for a modulation signal. The semiconductor laser 13 is arranged on the first microstrip line 22. The first microstrip line 22 is bent at a right angle at the direction changing portion 24 to change the propagation direction of the modulated signal to a right angle.

A second microstrip line 25 passes through the module package 11 so as to face the end of the first microstrip line 22 bent at a right angle, and is shared with an external terminal. The modulation signal 19 is input to the second microstrip line 25 from outside the module package 11.
Further, an inner end of the second microstrip line 25 and an opposite end of the first microstrip line 22 are connected by a bonding wire 26, and the modulation signal 19 is supplied to the second microstrip line 22. Track 2
5 to the first microstrip line 22. The semiconductor laser 14 is modulated by the modulation signal 19, and the modulation signal light is coupled to the optical fiber 15 and travels in the optical axis direction 27 shown by the arrow.

As described above, in the semiconductor laser module shown in FIG. 4, the second microstrip line 22 has a length corresponding to the length of the portion parallel to the optical axis of the optical fiber 15 in the second microstrip line 22.
Of the microstrip line 25 can be arranged on the left side in the drawing of the module package 11. This facilitates wire bonding and increases the degree of freedom in arranging external terminals for applying the modulation signal 19.

[0010]

By the way, in the optical fiber transmission system, the speed of the semiconductor laser module has been demanded in response to the demand for the speed. Especially G
In order to realize a high-speed semiconductor laser module in the (giga) Hz band, it is necessary to suppress loss and reflection in electrical connection between the semiconductor laser drive circuit and the semiconductor laser. For this purpose, it is effective to use the strip lines 17, 22, 25 as shown in FIGS.

However, in the conventional semiconductor laser module shown in FIG. 4, in order to solve the problem existing in the semiconductor laser module shown in FIG. 3, a direction changing section 24 is provided in the first microstrip line 22. The direction of propagation of the modulated signal is changed to a right angle. For this reason, reflection or loss of the modulation signal may occur in this portion. Therefore, in order to avoid such a problem, it is necessary to set the modulation frequency of the semiconductor laser module to a frequency lower than about 20 GHz, which has been a serious obstacle in increasing the speed.

An object of the present invention is to provide a semiconductor laser module that can reduce the reflection and loss of a modulation signal in a module even when the modulation frequency is high, and can sufficiently cope with high speed operation. .

[0013]

According to the first aspect of the present invention, there are provided (a) a module package, (b) a first linear microstrip line provided inside the module package, and (c) a first microstrip line. A semiconductor laser which is disposed on the first microstrip line and whose signal propagation direction matches the direction in which laser light is emitted; and (d) a signal propagation direction different from the signal propagation direction of the first microstrip line. (E) an optical fiber disposed outside the module package, (e) an optical fiber disposed outside the module package, and (f) an optical fiber disposed outside the module package.
Coupling means for coupling the semiconductor laser and the optical fiber;
(G) A semiconductor laser module is provided with a bonding wire connecting between the first microstrip line and the second microstrip line.

That is, according to the first aspect of the invention, while the semiconductor laser is arranged on the first microstrip line so that the signal propagation direction and the laser light emission direction coincide with each other, the semiconductor laser is arranged in a direction different from this. By disposing two microstrip lines and connecting them with a bonding wire, a bent direction conversion unit is not required, and even if the modulation frequency is high, the reflection and loss of the modulation signal in the module can be reduced. Made it possible.

According to the second aspect of the present invention, the second microstrip line is disposed substantially perpendicular to the first microstrip line, and is connected to an external terminal or the second microstrip line. And external terminals are easily shared.

According to the third aspect of the present invention, the second microstrip line is formed integrally with one of the external terminals protruding from the module package to the outside, thereby simplifying the configuration.

[0017]

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

FIG. 1 shows the configuration of a semiconductor laser module according to an embodiment of the present invention. 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In the semiconductor laser module of this embodiment, a carrier 31 made of a metal plate or the like is disposed on a Peltier element (not shown) on the incidence side of the lens 14 in the module package 11, and a ceramic plate and a metal plate are placed thereon. Are arranged in parallel with the optical axis direction of the optical fiber 15. Further, a semiconductor laser 13 is disposed on the surface near the end of the first microstrip line 32 on the side of the lens 14 so that the light axis of the lens 14 coincides with the emission direction.

The first microstrip line 32
And one end of a second microstrip line 34 is arranged so as to be close to the other end of the second microstrip line 32 and perpendicular to the first microstrip line 32. The second microstrip line 34 is a module package 11
One of a plurality of external terminals (other external terminals and circuit parts related to them are not shown) projecting to the outside through the side wall of the package 11 and projecting from both sides of the package 11. I have. The modulation signal 19 is externally applied to the second microstrip line 34. The other end of the first microstrip line 32 and the inner end of the second microstrip line 34 are connected by a bonding wire 36.

The second microstrip line 34
The external terminal for applying the modulation signal 19 and the external signal need not be formed integrally, but may be formed separately.

In the semiconductor laser module of this embodiment having such a configuration, the modulation signal applied from the outside to the second microstrip line 34 is
Accordingly, the light is propagated to the first microstrip line 32. Then, the direction in which the modulated signal propagates is rotated by 90 degrees by the first microstrip line 32 and transmitted to the semiconductor laser 13. The semiconductor laser 13 receives the modulation signal and outputs a modulation signal light. This modulated signal light is condensed by the lens 14 and
Will be combined.

FIG. 2 shows the modulation frequency characteristics of the semiconductor laser module of this embodiment in comparison with the conventional semiconductor laser module shown in FIG. In this figure, the horizontal axis shows the modulation frequency (GHz) applied to the corresponding pin of the module package 11, and the vertical axis shows the relative intensity when the light intensity is set to "0" when the frequency is relatively low. The intensity is expressed in dB (decibel).
One characteristic curve 41 shows the characteristics of the semiconductor laser module of the present embodiment, and the other characteristic curve 42 shows the characteristics of the conventional semiconductor laser module shown in FIG.

As shown by the broken line in this figure, the 3 dB band of the conventional semiconductor laser module shown in FIG.
Hz. On the other hand, the semiconductor laser module of this embodiment has a frequency of 25 GHz. For the former,
The modulation frequency band is thus limited to 20 GHz or less due to the influence of reflection and loss of the modulation signal in the direction conversion unit 24 of the first microstrip line 22 shown in FIG.

On the other hand, in the semiconductor laser module of the present embodiment, the first and second microstrip lines 32 and 34 are connected by bonding wires 36.
Therefore, the direction change of the modulation signal is performed at the bonding wire 36. The bonding wire 36 is 3
It has a transmission characteristic that hardly depends on the propagation direction of the modulated signal up to about 0 GHz. Therefore, even if the first and second microstrip lines 32 and 34 are arranged so as to be perpendicular to each other, the direction conversion of the modulated signal is performed without deteriorating the transmission characteristics. As a result, in the semiconductor laser module of the present embodiment, 20 GHz
The above modulation frequency band can be obtained.

[0025]

As described above, according to the first aspect of the present invention, while the semiconductor laser is arranged on the first microstrip line so that the signal propagation direction and the laser light emission direction are matched, Arranged the second microstrip lines in different directions and connected them with bonding wires, so that there was no direction change part bent from the microstrip lines, and even if the modulation frequency was high, The reflection and loss of the modulation signal can be reduced. Therefore, the modulation frequency can be increased to the upper limit of the frequency of the modulation signal received due to the transmission characteristics of the modulation signal at the bonding wire portion, as compared with the case where the direction conversion unit is present, and the modulation frequency band is widened.

According to the second aspect of the present invention, the first
Since the second microstrip line is arranged in a direction substantially perpendicular to the microstrip line,
Connection with the external terminal or sharing of the second microstrip line with the external terminal can be facilitated.

According to the third aspect of the present invention, the second microstrip line is integrally formed with one of the external terminals protruding from the module package to the outside, so that the cost of the semiconductor laser module can be reduced. Can be planned.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a main part of a semiconductor laser module according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a modulation frequency characteristic of the semiconductor laser module of the present embodiment in comparison with a conventional semiconductor laser module.

FIG. 3 is a cross-sectional view illustrating the configuration of an example of a conventionally proposed semiconductor laser module.

FIG. 4 is a cross-sectional view showing the configuration of another example of a conventionally proposed semiconductor laser module.

[Explanation of symbols]

 11 Module Package 13 Semiconductor Laser 14 Lens 15 Optical Fiber 19 Modulated Signal 31 Carrier 32 First Microstrip Line 34 Second Microstrip Line 36 Bonding Wire

Claims (3)

(57) [Claims] 1. A module package, a first linear microstrip line provided inside the module package, a signal propagation direction and a laser light emitting direction disposed on the first microstrip line. And a linear shape for setting a signal propagation direction to a direction different from the signal propagation direction of the first microstrip line and transmitting a semiconductor laser modulation signal supplied from outside the module package to the inside. A second microstrip line, an optical fiber disposed outside the module package, coupling means for coupling the semiconductor laser to the optical fiber, and a first microstrip line and a second microstrip line. And a bonding wire connected between them. Conductor laser module. 2. The semiconductor laser module according to claim 1, wherein the second microstrip line is disposed substantially perpendicular to the first microstrip line. 3. The semiconductor laser module according to claim 1, wherein said second microstrip line is integrally formed with one of external terminals projecting outside from a module package.