JPH0719932B2 - Laser diode module - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electronic component, particularly an electronic component for optical communication having a light emitting element and an optical fiber.

[Conventional technology]

A laser diode module (hereinafter referred to as an LD module) is used as one of the light sources for optical communication.

FIG. 3 is a cross-sectional view showing a conventional LD module described in, for example, Proceeding C-215 of the Autumn National Convention of the Institute of Electronics, Information and Communication Engineers in 1988. In the figure, (1) indicates a laser diode (hereinafter referred to as LD). ), (2) is the first lens that uses the light emitted from this LD as a collimated beam, and (3) is this
An optical isolator that passes the light emitted from the LD but conversely blocks the light that is about to enter the LD, (4) is a second lens that collects the light that passes through the optical isolator, and (5) is the above-mentioned A single mode fiber for propagating the condensed beam by the lens of (2), (6) is a monitor photodiode for receiving the rear emission light from the LD, (7) is the LD,
Lens, a chip carrier holding a monitor photodiode, (8) a thermistor for detecting the temperature of the chip carrier, (9) a Peltier element for controlling the temperature of the chip carrier, and (10) the LD. It is a package that hermetically seals elements such as.

Next, the operation will be described. The laser beam emitted by the LD (1) passes through the first lens (2), the optical isolator (3), and the second lens (4), and becomes the propagation light of the single mode fiber (5). This propagating light output is
The back light from the LD (1), which is almost proportional to this, is received by the monitor photodiode and monitored. Moreover, since the light emitted from LD (1) depends on the temperature of LD,
The temperature of the LD can be controlled by the thermistor (8) for temperature detection and the Peltier element (9) for temperature control. A package (10) hermetically seals an element such as an LD (1).

Next, the chip carrier (7) holding the LD (1) and the like will be described in more detail. The LD module shown in Fig. 3 is often used as a light source for high-speed digital optical communication of 2.4 gigabits or more and microwave optical transmission of 1 GHz or more. At this time, the power supply system to the LD (1) is important. Is. Figure 4 shows a schematic diagram of a chip carrier that has a power supply system to the LD that is suitable for such applications. In FIG. 4, (1) is an LD, (13) is a submount for mounting the LD, (14) is a heat sink for fixing the submount,
(15) is a ceramic substrate brazed to the heat sink (14), (16) is an Au pattern formed on the ceramic substrate, (17) is an LD (1) and Au pattern (1
It is a bonding wire that electrically connects between 6). The monitor photodiode and the like shown in FIG. 3 are omitted.

The submount (13) and the heatsink (14) are made conductive by means such as Au metallization, and the power is supplied to the LD by passing a current between the Au pattern (16) and the heatsink (14). It is realized by At this time, since the micro strip line is formed by the Au pattern (16) and the heat sink (14), the characteristic impedance of the feeding system to the chip carrier is changed to the characteristic of the micro strip line formed on the chip carrier. By matching the impedance, the effects of the parasitic inductance and parasitic capacitance of the power feeding system to the LD can be eliminated. By incorporating the chip carrier with this structure, the high frequency characteristics of the LD module are also improved. However, as the characteristic impedance of the micro strip line formed on the chip carrier,
Due to material restrictions, only values of 25 to 75 Ω are practical. Therefore, an LD whose impedance is about several Ω
And, of course, signal reflection occurs due to impedance matching between the micro strip line and the above.

As a means for preventing such signal reflection, a method using a resistor is generally used. 5 and 6 can be easily inferred as specific examples.

Figure 5 shows that part of the Au pattern (16) is a thin film resistor (1
The structure is the same as that shown in Fig. 4 except that it is 8). By adopting such a configuration, the impedance generated in the chip carrier shown in FIG. 4 can be obtained by making the sum of the impedances of the resistor (18) and the LD (1) and the characteristic impedance of the pattern (16) almost match. The problem of inconsistency can be eliminated.
FIG. 6 shows that a resistor chip (19) is soldered in place of the resistor (18) in FIG.
Except for that, FIGS. 5 and 6 have the same structure.

[Problems to be Solved by the Invention]

In the embodiment as shown in FIG. 5 in which the power feeding system to the LD is taken into consideration in order to improve the high frequency characteristics of the LD module, the power consumption of the resistor becomes larger than that of the LD, and the power consumption of the resistor becomes large. When used in the LD module shown in (1), there was a problem that extra power was required to cool the chip carrier (7). In addition, as a matter of course, in order to use such an LD module for communication, the LD
It was necessary to use a higher output drive circuit.

For the above reasons, LD is used for high frequency signals such as microwaves.
LD modules with a resistor placed in series with the LD are suitable for direct modulation, and when operating at frequencies below that, the resistor does not have a built-in resistor in terms of power consumption. LD module is suitable.

The chip carrier shown in FIG. 6 seems to be able to meet such two purposes, and by using a conductor instead of the resistor (19), the power consumption is small.
An LD module can be provided. However, the parasitic capacitance of the soldered part of the register chip cannot be ignored and the frequency characteristics are limited.

An object of the present invention is to provide an LD module in which a resistor is arranged in series with the LD in order to prevent reflection of an electric signal input to the LD from the LD module, and an LD module in which a resistor is not built in to prioritize reduction of power consumption. The point is to obtain a chip carrier that can be used in common with the module.

[Means for Solving the Problems]

The LD module according to the present invention uses, as a chip carrier incorporated in the LD module, a microstrip line and a vapor-deposited resistor made of a thin film, and a wire wired to short-circuit the resistor.

The LD module according to the present invention uses, as a chip carrier incorporated in the LD module, a microstrip line, a vapor-deposited resistor made of a thin film, and a wire wired to short-circuit the resistor. The LD module used at low frequencies can be handled as if there is no series resistance to the LD by incorporating the chip carrier as it is, and it consumes less power than the LD and resistor connected in series. Few. In addition, for the LD module used at high frequencies such as the microwave band, by using the chip carrier in which the wire shorting the resistor is cut, the characteristic impedance of the feed line to the LD and the LD and the resistor are formed. The impedance of the parts to be matched can be matched, making it an LD module suitable for directly modulating an LD with a high-frequency signal. The same chip carrier can be used for such incompatible purposes.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, (1) is an LD, (5) is a single mode fiber for propagating the light emitted from the LD (1), (6) is a monitor photodiode for receiving the rear light emitted from the LD, (14) ) Is a heat sink for holding the LD and the photodiode for monitoring, (15) is a ceramic substrate brazed by the heat sink (14), (16) is an Au pattern formed on the ceramic substrate (15), (17) is a bonding wire for electrically connecting the LD (1) and the Au pattern (16), (18) is a thin film resistor inserted in a part of the Au pattern (16), and (20) is The second bonding wire (21) wired to short-circuit the thin film resistor (18) is the Au pattern (16).
A second ceramic substrate connected to the (22) is the second ceramic substrate.
Second Au pattern formed on the ceramic substrate of
(23) is a third bonding wire for connecting the Au pattern (16) and the second Au pattern (22),
(8) is a thermistor for detecting the temperature of the heat sink, (9) is a Peltier element for controlling the temperature of the heat sink, (10) is a package for hermetically sealing elements such as the LD, and (24) is the package Electrode pins (25) penetrating through are fiber fixing members for fixing the optical fiber (5) penetrating the package onto the heat sink (14).

Next, the operation will be described. The laser beam emitted by the LD (1) becomes propagation light of the single mode fiber (5). This propagating light output is almost proportional to this LD
It is monitored by receiving the back light from (1) with a monitoring photodiode. Since the light emitted from the LD (1) depends on the temperature of the LD, the temperature of the LD can be controlled by the thermistor (8) for temperature detection and the Peltier element (9) for temperature control. LD (1)
The package (10) hermetically seals the elements such as.

Next, the power feeding system to LD (1) will be described. First, the first
When the module shown in the figure is used as it is, there is no resistor between the electrode pin (24) and the LD (1), and therefore the LD module has low power consumption. The anode terminal of the LD (1) is connected to the heat sink (14).
Au metallization is applied to the entire back surface of the second ceramic substrate (21), and the metallized surface is connected to the package (10) and the heat sink (14) by soldering. That is, the LD anode terminal is short-circuited to the package. On the other hand, the cathode terminal of the LD (1) has a bonding wire (17) and a second bonding wire (2
0), the Au pattern (16), the third bonding wire (23), and the Au pattern (22) in FIG. 2 are connected to the electrode pins (24). Therefore, the electrode pin (2
L by applying a current between 4) and the package (10)
Power is supplied to D (1).

In this case, since no current flows through the resistor (18), there is no extra power consumption in the resistor (18). In addition, even when considering high frequency input, the power is fed to the vicinity of LD (1) by a microstrip line, so if the line characteristic impedances are uniform, the effects of the line parasitic inductance and parasitic capacitance Can be removed. Where L
The impedance of D (1) is about several Ω, and impedance mismatch with the line, which has a characteristic impedance of about 25 to 75 Ω, cannot be avoided. Therefore, it is not suitable for high frequency transmission such as microwaves.

In such a case, the second bonding wire (20)
It is good to cut off with tweezers. By doing so, the input impedance is equal to the thin film resistor (18) and LD.
It becomes the sum of the impedances of (1), and it becomes possible to achieve impedance matching with the feed line. That is, the LD module is suitable for high-frequency transmission such as microwaves.

In other words, connect the second bonding wire,
The application field of the LD module can be changed depending on whether to cut.

FIG. 2 shows an enlarged view of the chip carrier portion. In the figure, (1) is an LD, (13) is a submount on which the LD (1) is mounted, (14) is a heat sink for fixing the submount, (15) is a ceramic substrate brazed to the heat sink (14), (16) is an Au pattern formed on the ceramic substrate, (17) is an LD (1) and Au pattern (1
6) Bonding wire for electrical connection between
8) is a thin film resistor inserted at the position of the Au pattern (16), (20) is a second bonding wire wired to short the thin film resistor (18), and (21) is an Au pattern. A second ceramic substrate connected to (16), (22)
Is a second Au pattern formed on the second ceramic substrate, and (23) is a bonding wire for connecting the Au pattern (16) and the second Au pattern (22). LD
Elements that are not related to power feeding to (1) are omitted.

Although the thin film resistor is used as the resistor (18) in the above embodiment, the same effect can be expected even if a thick film resistor is used.

Further, although one resistor (18) is shown, the same effect can be obtained even if it is composed of a plurality of resistors and wires.

Although only one second bonding wire (20) is shown, a plurality of wires or Au ribbons may be used to improve high frequency characteristics and reliability.

〔The invention's effect〕

As described above, according to the present invention, as the chip carrier used in the LD module, the microstrip line, the thin film vapor-deposited resistor, and the one having the wire wired to short-circuit the resistor are used. LD module suitable for high-frequency transmission of waves and low power consumption
There is an effect that the LD module can be obtained with the same chip carrier.

[Brief description of drawings]

FIG. 1 is a perspective view showing an LD module according to an embodiment of the present invention, FIG. 2 is a perspective view showing an LD power feeding portion of the LD module, and FIG. 3 is a sectional view showing a conventional LD module.
FIG. 6 is a perspective view showing an example of a conventional LD module chip carrier, FIG. 5 is a perspective view showing another example of a conventional LD module chip carrier, and FIG. 6 is another perspective view of a conventional LD module chip carrier. It is a perspective view which shows an example. (1) is a laser diode, (5) is a sigle mode fiber, (14) is a heat sink, (15) is a ceramic substrate, (18) is a resistor, and (20) is a second bonding wire. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A laser diode, a heat sink for holding the laser diode, a dielectric substrate fixed on the heat sink, a resistor formed on the dielectric substrate by means such as vapor deposition, and the resistor. A laser diode module, comprising: a conductor such as a wire wired to short-circuit; and an optical fiber that propagates light from the laser diode.