JP2002009384A - Semiconductor laser module, driving method of semiconductor laser module and communication equipment using semiconductor laser module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the passage of anaovercurrent through a thermomodule. SOLUTION: A thermomodule 5 performs a heating operation when a current in the direction to turn from a lead pin 16f to a lead pin 16a is passed through the thermomodule 5 and to the contrary, the thermomodule 5 performs a cooling operation when a current in the direction to turn from the lead pin 16a to the lead pin 16f is passed through the thermomodule 5. An overcurrent limiting circuit 20 for suppressing the passage of an overcurrent in the heating direction through the thermomodule 5 is provided. The circuit 20 has a by-pass passage 21, a Zener diode 22 and a diode 23 and the Zener diode 22 and the diode 23 are reversely connected with each other. When a current in the heating direction is passed through the thermomodule 5, the diode 23 turns on and when the Zener voltage of the Zener diode 22 exceeds its set value, the current is shunted into the thermomodule 5 and the passage 21 to flow. Hereby, the passage of the overcurrent through the thermomodule 5 can be suppressed.

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 in the field of optical communication, a method of driving the semiconductor laser module, and a communication device using the semiconductor laser module.

[0002]

2. Description of the Related Art FIG. 7A schematically shows an example of a structure of a semiconductor laser module by a cross section, and FIG. 7B shows an example of electric wiring of the semiconductor laser module shown in FIG. It is shown. The semiconductor laser module 1 shown in FIG. 7A is a module in which a semiconductor laser element 2 and an optical fiber 3 are optically coupled.

[0005] That is, as shown in FIG. 7 (a), a thermo module 5 is provided on an inner bottom wall surface 4 a of a package 4. In the thermo module 5, a plurality of Peltier elements 5a are plate members 5b and 5c (first substrate, second substrate) made of an insulating substrate such as alumina or aluminum nitride.
It is in a form sandwiched by. In this example,
The plate member 5b is fixed on the inner bottom wall surface 4a of the package 4. The radiating side of the Peltier element 5a is mounted on the plate member 5b by soldering. The plate member 5c is fixed on the heat absorbing side of the Peltier element 5a by soldering. Have been.

In such a thermo module 5, a heating operation (heating operation) and a heat absorbing operation (cooling operation) change according to the direction of the current flowing through the Peltier element 5a. It changes according to the amount of current flowing in 5a.

On the upper side of the thermo module 5 (that is, on the plate member 5c), a substrate 6 as a component mounting member is soldered (for example, InPbAg eutectic solder (having a melting point of 1).
48 ° C.)). Support members 7, 8 and a lens 9 are fixed above the substrate 6. The semiconductor laser element 2 is disposed on the support member 7 and a thermistor 10 for detecting the temperature of the semiconductor laser element 2 is provided. The support member 8 is provided with a monitoring photodiode 11 for monitoring the light emitting state of the semiconductor laser element 2. As the semiconductor laser device 2, for example, a 1310 nm band and 1
550 nm band signal light wavelength band, 1480 nm band or 9
The wavelength band of the pump light of the optical fiber amplifier such as the 80 nm band is generally used.

A through hole 4c is formed in a side wall 4b of the package 4, and an optical fiber supporting member 12 made of Kovar (trade name) or the like is fitted into the through hole 4c.
The optical fiber support member 12 has an insertion hole 12a, and the end side of the optical fiber 3 is introduced from the outside of the package 4 into the inside of the insertion hole 12a. Also, the insertion hole 12a
A lens 14 is disposed inside the optical fiber 3 with an interval from the tip of the optical fiber 3.

As shown in FIG. 7B, a plurality of lead pins 16 (14 in the example shown in FIG. 7B) are formed on the package 4 so as to protrude outward. Also,
Inside the package 4, the semiconductor laser element 2, the thermo module 5, the thermistor 10, the photodiode 1
Conductive means 17 such as a conductor pattern or a lead wire for electrically connecting the lead wire 1 to the lead pin 16 is provided.
The semiconductor laser device 2, the thermomodule 5, the thermistor 1 are connected to the conducting means 17 and the lead pins 16 by the conducting means 17 and the lead pins 16.
0, the photodiodes 11 can be electrically connected to drive control means (not shown) for driving the semiconductor laser module.

More specifically, in the example shown in FIG. 7B, the semiconductor laser element 2 is connected to the conducting means 17 and the lead pins 16 (16g, 16h), and the thermomodule 5 is connected to the conducting means 17 and the lead pins. 16 (16a,
16f), the thermistor 10 is conductively connected to the drive control means by the conductive means 17 and the lead pins 16 (16b, 16e), and the photodiode 11 is conductively connected to the drive control means by the conductive means 17 and the lead pins 16 (16c, 16d). You.

The semiconductor laser module 1 shown in FIG. 7 is configured as described above. When such a semiconductor laser module 1 is conductively connected to the drive control means and a current is supplied from the drive control means to the semiconductor laser element 2 of the semiconductor laser module 1, laser light is emitted from the semiconductor laser element 2. The emitted laser light is condensed by the coupling optical system composed of the lenses 9 and 14, is incident on the optical fiber 3, propagates in the optical fiber 3, and is used for a desired application.

The intensity and wavelength of the laser light emitted from the semiconductor laser device 2 fluctuate according to the temperature of the semiconductor laser device 2 itself. For this reason, in order to control the intensity and wavelength of the laser light to be constant, the drive control means operates based on the output value output from the thermistor 10 so that the temperature of the semiconductor laser element 2 becomes constant. The heating operation or the cooling operation of the thermomodule 5 is controlled by controlling the direction and amount of current supplied to the module 5. By the temperature control by the thermo module 5, the semiconductor laser element 2 is maintained at a substantially constant temperature, and the intensity and wavelength of the laser light emitted from the semiconductor laser element 2 can be made constant.

[0011]

However, an abnormal situation may occur in which an overcurrent in the heating direction for heating the thermomodule 5 is supplied to the thermomodule 5 due to, for example, an operation error or occurrence of an overvoltage. . In this case, the thermo-module 5 is heated to an abnormally high temperature, and the components such as the semiconductor laser device 2, the substrate 6, the lens 9 and the like disposed on the thermo-module 5 are changed to a temperature of 200 ° C. for 10 seconds, for example. It is heated rapidly as it rises above.

By the way, the plate member 5c of the thermo module 5 is connected to the side wall of the package 4 or the optical fiber supporting member 12a.
When the thermal module 5 is thermally connected, a part of the heat generated from the thermo module 5 is released to the outside via the side wall of the package 4 and the optical fiber supporting member 12. For this reason, when the thermo module 5 is abnormally heated to a high temperature as described above, a part of the high temperature heat is radiated to the outside from the thermo module 5 via the optical fiber supporting member 12, and the semiconductor The amount of heat transferred to the components on the thermo module 5 such as the laser element 2 and the lens 9 is suppressed, and the temperature rise of the components on the thermo module 5 can be reduced.

However, in the example shown in FIG. 7, the components on the thermo module 5 and the side wall of the package 4 and the optical fiber supporting member 12 are in a thermally independent state. For this reason, the heat of the components on the
Package 4 through side wall of optical fiber support member 12
The heat is hardly radiated outside. In such a case, when abnormal high-temperature heating of the thermo-module 5 occurs, the high-temperature heat of the thermo-module 5 is transmitted to components on the thermo-module 5 and accumulated. For this reason, the temperature rise of the components on the thermo module 5 becomes remarkable, and the following situation is likely to occur, which is a problem.

For example, as described above, when the temperature of the semiconductor laser element 2 rises to a high temperature due to the high temperature heating of the thermo module 5 caused by the overcurrent flow in the heating direction, the defect inside the crystal of the semiconductor laser element 2 becomes defective. This causes a problem that the characteristics of the semiconductor laser element 2 are greatly deteriorated.

As described above, the substrate 6 is fixed to the plate member 5c of the thermo module 5 by a solder (hot-melt connection material) such as, for example, InPbAg eutectic solder (melting point: 148 ° C.). For this reason, when the thermo module 5 is abnormally heated to a high temperature as described above, the solder may be melted and the substrate 6 may be displaced. Due to the displacement of the substrate 6, the semiconductor laser element 2 and the lens 9 are displaced from their normal positions, and a displacement of optical coupling (alignment deviation) occurs in which the semiconductor laser element 2 and the lens 9 are displaced with respect to the optical fiber 3. The problem arises. In particular, when the semiconductor laser element 2 causes an angular shift with respect to the optical fiber 3 due to the positional shift of the substrate 6, for example, 0.2 °
As a result, the optical output is greatly reduced, for example, the optical output is reduced by as much as 95% due to the angular deviation.

Further, the glass lens 9 is adhered and fixed to a metal holder using low-melting glass, for example. The metal holder with the lens is fixed to the substrate 6 so that the lens 9 is attached to the substrate 6. May be attached to. In this case, as described above, when the thermo module 5 suddenly abnormally heats, a large difference in the coefficient of thermal expansion between the glass and the metal causes a large difference in the thermal expansion coefficient between the lens 9 and the metal holder (low-melting glass). Cracks occur. Due to the occurrence of the crack, the lens 9 comes off from the metal holder, causing a problem that optical coupling between the semiconductor laser element 2 and the optical fiber 3 is impaired.

Further, as described above, the Peltier element 5
a and the plate members 5b and 5c are connected by using solder, so that the abnormal melting of the thermo module 5 causes the solder to melt and the Peltier element 5a to come off, for example, to break the thermo module 5 itself. There is a risk of doing so.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to prevent an overcurrent from flowing to a thermo module in a heating direction and avoid a problem caused by the overcurrent. It is an object of the present invention to provide a semiconductor laser module and a driving method of the semiconductor laser module that can be used.

[0019]

Means for Solving the Problems In order to achieve the above object, the present invention has the following structure to solve the above problems. That is, a semiconductor laser module according to a first aspect of the present invention includes a semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device, and an optical fiber optically coupled to laser light emitted from the semiconductor laser device. In the semiconductor laser module having a configuration, the thermo module changes a heating operation and a cooling operation in accordance with the direction of an energizing current, and variably adjusts the temperature of the semiconductor laser element in accordance with the amount of current applied to the thermo module. A bypass path for short-circuiting the upstream and downstream sides of the thermo module by bypassing the thermo module is provided on a current path for flowing a current in a heating direction for heating the thermo module to the thermo module. In the passage, a diode whose heating direction is the forward direction, and a reverse direction to the diode The bypass path, the diode and the Zener diode shunt the current in the heating direction to the thermo module and the bypass path to prevent overcurrent in the heating direction from flowing to the thermo module. The present invention is a means for solving the problem with a configuration serving as an overcurrent limiting means for suppressing.

Further, in the semiconductor laser module according to the second aspect of the invention, in addition to the configuration of the first aspect, the thermo module is configured by sandwiching a Peltier element between a first substrate and a second substrate. A semiconductor laser device is disposed on one of the substrate and the second substrate, and is thermally connected to the thermo module. The laser beam emitted from the semiconductor laser device is collected and collected. It has a lens for introduction into the fiber, and the lens is thermally connected to the substrate on the side where the semiconductor laser element of the thermo module is arranged via a hot-melt connection material fixing the mounting member of the lens. The configuration to be connected is a means for solving the problem.

Further, in the semiconductor laser module according to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the optical fiber transmits laser light emitted from the semiconductor laser element to an end where the laser light is incident. The configuration is an optical fiber with a lens on which a converging lens is formed.

Further, in the semiconductor laser module according to a fourth aspect of the invention, in addition to the configuration of the first, second, or third aspect of the invention, the thermo module includes a Peltier element sandwiched between a first substrate and a second substrate. A semiconductor laser element is disposed on one of the first substrate and the second substrate and is thermally connected to a thermo module. The semiconductor laser element and the thermo module are The package is accommodated and arranged, and the package is provided with a through hole communicating from the inside of the package to the outside, and an optical fiber supporting member is fitted and mounted in the through hole, and provided in the optical fiber supporting member. The end side of the optical fiber is introduced from outside to inside of the package through the insertion hole, and the substrate on the side where the semiconductor laser element of the thermo module is arranged The problem is solved by a configuration in which heat release from the substrate on the side on which the semiconductor laser element of the thermo module is disposed to the outside of the package via the optical fiber supporting member is thermally independent of the optical fiber supporting member. Means to do that.

Further, a driving method for a semiconductor laser module according to a fifth aspect of the present invention is a semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device, and a laser light emitted from the semiconductor laser device. In the method of driving a semiconductor laser module having an optical fiber to be coupled, the thermomodule changes a heating operation and a cooling operation in accordance with the direction of an energizing current, and changes a semiconductor laser in accordance with an amount of current supplied to the thermomodule. The temperature of the element is variably adjusted. This thermo module is thermally connected to the semiconductor laser element, and the current in the heating direction for heating the thermo module flows through the thermo module. With a bypass passage that shorts the thermometer module and the downstream side In this bypass passage, a diode having the heating direction as the forward direction and a Zener diode in the opposite direction to the diode are provided in series, and the voltage at both ends of the Zener diode exceeds a threshold value preset for the Zener diode. Sometimes, the current in the heating direction is diverted to the bypass passage to suppress the overcurrent from flowing to the thermo module in the heating direction.

Further, a communication device according to a sixth aspect of the present invention is a communication device, comprising: a semiconductor laser element, a thermo module for adjusting the temperature of the semiconductor laser element, and a light optically coupled to the laser light emitted from the semiconductor laser element. In a communication device including a semiconductor laser module having a fiber,
The thermo module changes the heating operation and the cooling operation in accordance with the direction of the supplied current, and variably adjusts the temperature of the semiconductor laser element in accordance with the amount of current supplied to the thermo module. A bypass path that short-circuits the upstream and downstream sides of the thermo module by bypassing the thermo module is provided on a current path that causes the current in the heating direction to be heated to flow to the thermo module,
In this bypass passage, a diode whose heating direction is the forward direction, and a Zener diode that is opposite to the diode are provided in series, and the bypass passage, the diode and the Zener diode pass current in the heating direction to the thermo module. The present invention is a means for solving the problem by providing a configuration in which a branch current is supplied to the bypass passage to prevent overcurrent in the heating direction from being supplied to the thermo module.

Further, in a communication device according to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect of the invention, the overcurrent limiting means is a means for solving the problem by having a configuration provided in a power supply device of the semiconductor laser module.

In the invention having the above-described structure, the semiconductor laser module bypasses the thermomodule with the upstream and downstream sides of the thermomodule on a current path through which a current in a heating direction for heating the thermomodule flows through the thermomodule. A short-circuited bypass passage, a diode whose forward direction is the heating direction, and a zener diode connected in series with the diode in a direction opposite to the diode are provided.

The bypass passage, the diode and the zener diode constitute overcurrent limiting means for suppressing overcurrent in the heating direction from flowing to the thermo module. The voltage at both ends of the zener diode is applied to the zener diode in advance. When the set threshold is exceeded (that is, when the Zener voltage of the Zener diode is exceeded)
Then, the current in the heating direction is divided and supplied to the bypass passage to suppress the overcurrent in the heating direction from flowing to the thermo module. Therefore, in the present invention, the overcurrent in the heating direction to the thermomodule can be suppressed by the overcurrent limiting means having a simple configuration having the bypass passage, the diode, and the zener diode.

In a semiconductor laser module equipped with a thermo module, if an over current in the heating direction is applied to the thermo module, the thermo module is heated to an abnormally high temperature, causing various problems. By adopting a configuration in which the limiting means is provided to suppress the overcurrent in the heating direction, it is possible to prevent various problems caused by the application of the overcurrent to the thermomodule in the heating direction. Therefore, the present invention can prevent problems such as deterioration of the characteristics of the semiconductor laser device due to abnormal heating of the thermomodule, problems of optical coupling shift, problems of optical coupling loss due to detachment of the lens, and problems of breakage of the thermomodule.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of electric wiring of a semiconductor laser module which is characteristic in the first embodiment. The feature of the first embodiment is that an overcurrent limiting circuit 20 as an overcurrent limiting means (reverse current limiting means) is provided as shown in FIG. The overcurrent limiting circuit 20 includes a bypass passage 21 and a Zener diode 2.
2 and a diode 23, and are provided inside the package 4.

The semiconductor laser module according to the first embodiment has the same configuration as that of the semiconductor laser module shown in FIG. 7 except for the above. Are denoted by the same reference numerals, and redundant description thereof will be omitted.

In many cases, the semiconductor laser module 1 is used in an environment at room temperature or higher, and it is often assumed that the thermo module 5 only performs a cooling operation. 5 is assumed to also perform the operation in the heating direction. That is, the first
In the embodiment, the thermo module 5 changes the heating operation and the cooling operation in accordance with the direction of the supplied current, and
The configuration is such that the temperature of the semiconductor laser element 2 is variably adjusted according to the amount of current supplied to the thermomodule 5.

In the first embodiment, when a current flows from the lead pin 16f to the lead pin 16a, the thermo module 5 performs a heating operation. Conversely, the thermo module 5 performs a heating operation from the lead pin 16a to the lead pin 1a.
When current flows in the direction toward 6f, the thermo module 5 is configured to perform a cooling operation.

In FIG. 1, one end of the bypass passage 21 is connected to a point X closer to the lead pin 16a than the thermo module 5, and the other end of the bypass passage 21 is connected to a point Y closer to the lead pin 16f than the thermo module 5. It is connected. With this configuration, the bypass passage 21 short-circuits the upstream side Y and the downstream side X of the thermomodule 5 in the current path in the heating direction to the thermomodule 5, bypassing the thermomodule 5.

The diode 23 is provided in the bypass passage 21 with the heating direction being the forward direction. Therefore, as shown in FIG. 2A, the diode 23 has a current flowing in the heating direction of the thermo module 5. It is configured to be in a conduction-on state when flowing, and to be in a conduction-off state when current flows in the cooling direction of the thermomodule 5.

The Zener diode 22 is provided in the bypass passage 21 in a direction opposite to the direction of the diode 23 (in other words, the cooling direction of the thermo module 5 is set to the forward direction). Therefore, the Zener diode 22
As shown in FIG. 2B, when a current flows in the cooling direction of the thermo module 5, the conduction is turned on. However, in the first embodiment, the Zener diode 2
2 is connected in series with the diode 23, so that when a current in the cooling direction flows through the thermomodule 5, the overcurrent limiting circuit 20 is configured to be kept off.

On the other hand, when a current flows in the thermo module 5 in the heating direction, the voltage at both ends of the thermo module 5, that is, the voltage at both ends of the zener diode 22 is set to a threshold value preset in the zener diode 22 (the zener of the zener diode 22). Voltage), the Zener diode 22 is turned off, and when the threshold value is exceeded, the Zener diode 22 is turned on.

Therefore, in the first embodiment,
Normally (when no overcurrent occurs), the overcurrent limiting circuit 20 is kept off during the operation of the thermomodule 5 in the heating direction, and when an overcurrent occurs in the heating direction, the diode 23 and the zener diode 22 are actuated. Are both in a conduction ON state, and a current in the heating direction is divided and supplied to the thermomodule 5 and the bypass passage 21 to suppress the overcurrent in the heating direction from being supplied to the thermomodule 5. .

The semiconductor laser module 1 according to the first embodiment is configured as described above.
An example of the circuit operation of the overcurrent limiting circuit 20 will be briefly described.

For example, the semiconductor laser module 1 is electrically connected to drive control means for driving the semiconductor laser module using the lead pins 16. In this state, when a current in a direction from the lead pin 16a to the lead pin 16f, that is, a current in a cooling direction for cooling the thermomodule 5 is supplied by the drive control means, the overcurrent limiting circuit 20 The diode 23 is turned off. Thus, the current in the cooling direction is
All flow into the thermo module 5 without supplying electricity to the bypass passage 21.

On the contrary, the current (reverse current) in the direction from the lead pin 16f to the lead pin 16a, that is,
When a current in the heating direction for heating the thermomodule 5 is applied, the diode 23 is turned on, but the voltage across the Zener diode 22 is lower than the threshold value (Zener voltage of the Zener diode 22). Until it exceeds, the conduction is off. Therefore, when the overcurrent in the heating direction does not occur, the current in the heating direction does not flow through the bypass passage 21 but all flows into the thermomodule 5.

When an overcurrent is generated in the heating direction, the current in the heating direction is divided and supplied to the thermomodule 5 and the bypass passage 21, so that all of the overcurrent is supplied to the thermomodule 5. Unlike this case, overcurrent supply to the thermomodule 5 can be suppressed.

In the first embodiment, as described above, the plate member 5c of the thermo module 5 on which the semiconductor laser element 2 is disposed is thermally connected to the side wall of the package 4 and the optical fiber support member 12. be independent. For this reason, when an overcurrent in the heating direction is supplied to the thermo module 5,
The heat of the high-temperature heating of the thermomodule 5 caused by the overcurrent conduction is generated by the side wall of the package 4 and the optical fiber supporting member 12.
The heat is not radiated to the outside of the package 4 through the components, but is stored in the components on the thermomodule 5, and various problems are likely to occur.

On the other hand, in the first embodiment, the overcurrent limiting circuit 20 is provided.
Thus, the configuration is such that overcurrent is supplied to the thermo module 5 in the heating direction, so that various problems due to overcurrent supplied to the thermo module 5 in the heating direction can be avoided.

That is, in the first embodiment, abnormal heating of the thermomodule 5 due to overcurrent in the heating direction can be suppressed.
Can be prevented from being heated to a high temperature. For this reason, in the first embodiment, it is possible to avoid the growth of defects inside the crystal of the semiconductor laser device 2 due to high-temperature heating, and to prevent the characteristic deterioration of the semiconductor laser device 2.

Further, in the first embodiment, a thermo-melting connection material such as solder for connecting the substrate 6 and the thermo-module 5, which are members for mounting components such as the semiconductor laser element 2 and the lens 9, is used. Can be prevented from being melted due to high-temperature heating of the substrate 6, whereby the displacement of the substrate 6 can be prevented. As a result, the first embodiment prevents the semiconductor laser device 2 and the lens 9 from being displaced with respect to the optical fiber 3, and the optical fiber 3
Optical coupling between the semiconductor laser device 2 and the semiconductor laser device 2 can be suppressed,
Light output can be prevented from lowering.

Further, in the first embodiment, it is possible to suppress the occurrence of cracks in the joint portion between the lens 9 and the metal holder due to the rapid temperature rise on the substrate (plate member) 5c side of the thermo module 5. . Thus, in the first embodiment, it is possible to prevent the lens 9 from coming off due to the occurrence of a crack, and to avoid a situation in which the optical coupling between the semiconductor laser element 2 and the optical fiber 3 is impaired. it can.

Further, in the first embodiment, the melting of the solder between the Peltier element 5a and the plate members 5b and 5c can be prevented, so that the thermo module 5 itself can be prevented from being damaged.

As described above, in the first embodiment, by providing the characteristic overcurrent limiting circuit 20, it is possible to prevent various problems caused by overcurrent supply to the thermo module 5 in the heating direction. Can be. Thus, in the first embodiment, the reliability of optical coupling and durability of the semiconductor laser module 1 can be remarkably improved.

In the first embodiment, the overcurrent limiting circuit 20 is provided with a bypass path 21, a diode 23 and a Zener diode 22. The voltage across the Zener diode 22 is equal to the voltage of the Zener diode 22. Until the Zener voltage is reached, the control of the heating direction of the thermo module 5 can be performed in the same manner as the control of the cooling direction. Therefore, the cooling operation and the heating operation of the thermo module 5 can be controlled as appropriate. As described above, an excellent semiconductor laser module capable of suppressing overcurrent in the heating direction can be obtained.

Further, in the first embodiment, the overcurrent limiting circuit 20 is formed with a simple configuration including the bypass passage 21, the diode 23, and the zener diode 22, so that such a very simple configuration is provided. Thus, the above excellent effects can be obtained.

Hereinafter, a second embodiment will be described. The feature of the second embodiment different from the first embodiment is that, as shown in FIG.
And a capacitor 25 for supplying a surge current. Other configurations are the same as those of the first embodiment. In the description of the second embodiment, the first embodiment will be described.
The same components as those of the embodiment are denoted by the same reference numerals, and the description thereof will not be repeated.

In the second embodiment, as described above, since the capacitor 25 is provided in parallel with the thermo module 5, when a surge current which is an instantaneous large current occurs, the surge current is reduced. The capacitor 25 is energized and the thermo module 5 is not energized. Thus, it is possible to prevent the thermo module 5 from being damaged due to the surge current supply.

That is, the surge current has a high frequency, and the impedance of the capacitor decreases as the frequency increases. For this reason, even if the surge current is generated and the thermo module 5 is to be energized,
Most of the surge current flows through the capacitor 25. Thereby, it is possible to suppress the surge current from flowing through the thermomodule 5, and it is possible to prevent the thermomodule 5 from being damaged due to the surge current.

Further, when a surge current in the heating direction is applied to the thermo module 5, the components on the thermo module 5 may instantaneously rise in temperature and cause various problems as described above. In the embodiment, as described above, since the surge current is suppressed from flowing through the thermo module 5 by the capacitor 25, the characteristic deterioration of the semiconductor laser device 2 as described above,
Various problems such as a problem of optical coupling deviation between the optical fiber 3 and the optical fiber 3 and a problem of optical coupling being lost due to the detachment of the lens 9 can be prevented.

According to the second embodiment, the first
Since the overcurrent limiting circuit 20 is provided in the same manner as in the first embodiment, the overcurrent limiting circuit 20 supplies overcurrent to the thermomodule 5 in the heating direction, as in the first embodiment. Can be suppressed, and various problems caused by overcurrent application in the heating direction can be prevented. In addition, since the capacitor 25 is provided in parallel with the thermo module 5 as described above, the capacitor 25 can also prevent a problem caused by surge current conduction.

It should be noted that the present invention is not limited to the above embodiments, but can take various embodiments. For example, in each of the above embodiments, the overcurrent limiting circuit 20
Is an example of a semiconductor laser module having an overcurrent limiting function provided in a package 4. For example, FIG.
As shown in FIG. 4, a bypass passage 21 and a Zener diode 22 surrounded by a dotted line in FIG. An overcurrent limiting circuit 20 including a diode 23 may be provided to drive the semiconductor laser module.

Further, similarly, the same capacitor 25 as that shown in the second embodiment may be provided outside the semiconductor laser module 1 as shown by a chain line in FIG.
The overcurrent limiting circuit 20 and the capacitor 25 provided outside the semiconductor laser module 1 shown in FIG. 4 are the overcurrent limiting circuit 20 and the capacitor 25 shown in each of the above embodiments.
And the same effects as those of the above embodiments can be obtained.

Further, in each of the above embodiments, FIG.
As shown in FIG. 5A, the coupling optical system is formed by using lenses 9 and 14 separate from the optical fiber 3.
As shown in (1), the coupling optical system may be formed by using the optical fiber with lens 3 without using the lenses 9 and 14. The optical fiber with lens 3 is an optical fiber provided with a lens 3a for condensing laser light emitted from the semiconductor laser device 2.

The optical fiber with lens 3 is incorporated in the semiconductor laser module 1 as shown below. For example, as shown in FIG. 5, a fixing member (for example, made of stainless steel) 27 is attached to the substrate 6, and an optical fiber supporting member 28 is fixed to the fixing member 27 by YAG laser welding or the like. In addition, the through hole 4 formed in the package 4
The optical fiber support member 29 is fitted and mounted on
It is fixed by a bonding material 30 such as solder. The optical fiber supporting members 28 and 29 are provided with insertion holes, respectively, and the optical fiber 3 is introduced into the package 4 from the outside through the insertion holes. They are arranged at appropriate intervals where optical coupling is achieved. The configuration other than the above is the same as the configuration shown in FIG. 7A, and the description thereof will not be repeated.

The optical fiber supporting members 28 and 29 are made of a heat conductive material such as an Fe-Ni-Co alloy. In the configuration shown in FIG. 5, the substrate (that is, the plate member 5c) of the thermo module 5 on which the semiconductor laser element 2 is disposed is strictly thermally connected to the optical fiber support member 29 through the optical fiber 3. I have. However, since the optical fiber 3 is made of quartz glass having a small diameter of, for example, about 125 μm, the optical fiber supporting member 29 passes through the optical fiber 3 from the plate member 5 c of the thermomodule 5.
Is very small.

As a result, the plate member 5c of the thermo module 5 is thermally independent from the optical fiber support member 29. That is, in the configuration shown in FIG.
The configuration is such that the release of heat from the plate member 5c of the thermo module 5 to the outside of the package 4 via the optical fiber support member 29 is restricted.

In such a configuration, as described above, when the thermo module 5 is abnormally heated to a high temperature due to the overcurrent flow to the thermo module 5, the high temperature heat is applied to the components on the thermo module 5. It accumulates and causes various problems. On the other hand, by providing a configuration for suppressing overcurrent supply to the thermomodule 5 as shown in each of the above embodiments, it is possible to prevent problems caused by overcurrent supply to the thermomodule 5. Can and is very effective.

FIG. 6 shows an optical fiber amplifier which is an example of the communication equipment of the present invention. The optical fiber amplifier 40 includes a signal light input unit 41 for inputting signal light, an EDF (erbium-doped fiber) 44 for amplifying the signal light input from the signal light input unit 41, and a signal light amplified by the EDF 44. A signal light output unit 42 for outputting, a semiconductor laser module for excitation (excitation semiconductor laser module) 1 for exciting the EDF 44, a power supply circuit (power supply device) 46 controlled by a control circuit 47 serving as drive control means; At least.

The power supply circuit 46 has a power supply section 45 for supplying power to the excitation semiconductor laser module 1 and an overcurrent limiting circuit 20 connected in parallel to the power supply section 45 and the excitation semiconductor laser module 1. And The overcurrent limiting circuit 20 includes a bypass passage 21, a zener diode 22, and a diode 23, as in the configuration shown in FIGS. In FIG. 6, reference numeral 43 denotes an optical coupler functioning as an optical wavelength multiplexer / demultiplexer.

Next, the operation of the optical fiber amplifier 40 will be described. For example, 1550 nm from the signal light input unit 41
The band signal light is input, and this signal light is input into the EDF 44 via the optical coupler 43. The pumping semiconductor laser module 1 generates pumping light in the 980 nm band or 1480 nm band, and converts this pumping light to E through the optical coupler 43.
Supply to DF44. The EDF 44 is excited by the pumping light output from the pumping semiconductor laser module 1, and amplifies the power of the input signal light. EDF
The signal light amplified at 44 is output from the signal light output unit 42.

Here, the semiconductor laser module for excitation 1
Is constantly input to the control circuit 47, and the control circuit 47 outputs a control signal based on the temperature information. The control signal is input to the power supply unit 45 of the power supply circuit 46. The power supply unit 45 supplies power to a thermo module (not shown in FIG. 6) in the semiconductor laser module 1 for excitation based on the control signal, and Module 1
An operation for keeping the internal temperature constant is performed.

In the optical fiber amplifier 40, as in the case of FIGS. 1, 3, and 4, when a current flows in the cooling direction of the thermo module of the semiconductor laser module 1 for excitation, the overcurrent limiting circuit 20 It is off,
When an excessive current flows in the heating direction of the thermomodule, the overcurrent limiting circuit 20 is turned on.

As described above, it is possible to suppress the overcurrent from flowing to the thermo module of the semiconductor laser module 1 for excitation.
The light output from the output is prevented from lowering,
The optical fiber amplifier 40 can stably amplify the signal light.

The semiconductor laser module, the driving method thereof, and the communication device according to the present invention can be applied to any device provided with a semiconductor laser module whose temperature is controlled by a thermo module.
Particularly used in optical fiber amplifiers as described above 98
In a semiconductor laser module for excitation in a 0 nm band or a 1480 nm band, a large amount of heat is generated from a semiconductor laser element and the semiconductor laser module is often used in a high temperature environment. The current is large. Therefore, the semiconductor laser module of the present invention, the driving method thereof, and the communication device are suitable as an excitation semiconductor laser module, a driving method thereof, and an optical fiber amplifier.

[0071]

According to the semiconductor laser module and the method of driving the semiconductor laser module of the present invention, overpower limiting means for suppressing the application of overcurrent in the heating direction to the thermomodule is provided. When the voltage exceeds a preset threshold value in the Zener diode, the current in the heating direction is shunted to the bypass passage to suppress the overcurrent in the heating direction from flowing to the thermo module. The overcurrent limiting means can suppress the overcurrent in the heating direction to the thermo module.

That is, when an overcurrent in the heating direction is applied to the thermo module, the thermo module is heated to an abnormally high temperature, causing various problems.
By providing an overcurrent limiting means to suppress overcurrent in the heating direction, various problems caused by overcurrent application to the thermomodule in the heating direction can be prevented.

Therefore, the present invention can prevent problems such as deterioration of the characteristics of the semiconductor laser device due to abnormal heating of the thermo module, problems of optical coupling shift, problems of optical coupling loss due to lens detachment, and problems of thermo module breakage. it can.

Further, in the semiconductor laser module of the present invention, the overcurrent limiting means is provided with a bypass path, a diode and a Zener diode, and the voltage across the Zener diode is set to a threshold value set to the Zener diode. Until the temperature reaches, the control of the heating direction of the thermo module can be performed in the same manner as the control of the cooling direction, so that the cooling operation and the heating operation of the thermo module can be freely controlled according to the application, and An excellent semiconductor laser module capable of suppressing current can be obtained.

Further, the substrate on the side of the thermo module on which the semiconductor laser element is disposed is thermally independent of the optical fiber supporting member, and the substrate from the thermo module substrate to the outside of the package via the optical fiber supporting member. In the case where the heat release is limited, when overcurrent is applied to the thermo module in the heating direction, the high temperature heat generated from the thermo module is not radiated to the outside of the package, Is transferred to and accumulated in components such as a semiconductor laser device that is thermally connected to the thermo module, which may cause a rapid rise in temperature of the components, causing various serious situations.

By providing an overcurrent limiting means characteristic of the present invention to such a configuration, it is possible to suppress the overcurrent from flowing to the thermo module in the heating direction. This is very effective because it can prevent a situation from occurring.

Further, according to the communication device of the present invention, overcurrent in the heating direction of the semiconductor laser module to the thermomodule can be suppressed by the overcurrent limiting means having a simple configuration, so that safe and accurate operation can be achieved. Excellent communication equipment can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of an electrical wiring of a semiconductor laser module which is characteristic in the first embodiment.

FIG. 2 is an explanatory diagram of an operation (a) of a diode 23 and an operation (b) of a zener diode 22 provided in the embodiment.

FIG. 3 is an explanatory diagram showing an example of electrical wiring of a semiconductor laser module which is characteristic in the second embodiment.

FIG. 4 is an explanatory diagram showing another embodiment.

FIG. 5 is an explanatory view showing still another embodiment.

FIG. 6 is an explanatory diagram showing an embodiment of a communication device according to the present invention.

FIG. 7 is an explanatory view showing one structural example of a semiconductor laser module and a conventional example of electric wiring of the semiconductor laser module.

[Description of Signs] 1 Semiconductor laser module 2 Semiconductor laser element 3 Optical fiber 4 Package 5 Thermo module 9, 14 Lens 12, 29 Optical fiber support member 20 Overcurrent limiting circuit 21 Bypass passage 22 Zener diode 23 Diode 25 Capacitor

Continuation of the front page (72) Inventor Takashi Koseki 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. F-term (reference) 2H037 AA01 BA03 DA35 DA38 5F073 AB27 AB28 BA02 BA09 FA07 FA25 GA23 GA32

Claims (7)

[Claims] 1. A semiconductor laser module comprising: a semiconductor laser device; a thermo module for adjusting a temperature of the semiconductor laser device; and an optical fiber optically coupled to laser light emitted from the semiconductor laser device. The thermo module changes the heating operation and the cooling operation in accordance with the direction of the supplied current, and variably adjusts the temperature of the semiconductor laser element in accordance with the amount of current supplied to the thermo module. A bypass path that short-circuits the upstream side and the downstream side of the thermo module by bypassing the thermo module is provided on a current path through which a current in the heating direction for performing the heating operation flows to the thermo module. A diode in the forward direction and a zener diode in the opposite direction are provided in series. The bypass passage, the diode and the Zener diode constitute overcurrent limiting means for dividing the heating direction current into the thermomodule and the bypass passage to suppress the overcurrent in the heating direction from flowing to the thermomodule. A semiconductor laser module characterized in that: 2. The thermo module includes a Peltier element as a first element.
A semiconductor laser element is disposed on one of the first substrate and the second substrate, and is thermally connected to the thermo module. A lens for condensing laser light emitted from a semiconductor laser element and introducing the laser light into an optical fiber, wherein the lens is a thermo-module via a hot-melt connection material fixing a member for mounting the lens. 2. The semiconductor laser module according to claim 1, wherein the semiconductor laser module is configured to be thermally connected to the substrate on which the semiconductor laser element is disposed. 3. The optical fiber according to claim 1, wherein the optical fiber is a lens-equipped optical fiber in which a lens for condensing the laser light emitted from the semiconductor laser element is formed at an end where the laser light is incident. The semiconductor laser module according to claim 2. 4. The thermo module includes a Peltier element as a first element.
And a semiconductor laser element is disposed on one of the first substrate and the second substrate and is thermally connected to the thermo module. The semiconductor laser device and the thermo module are housed and arranged in a package, and the package is provided with a through hole extending from the inside of the package to the outside, and an optical fiber supporting member is fitted and mounted in the through hole. The end of the optical fiber is introduced from the outside of the package to the inside through the insertion hole provided in the optical fiber support member, and the substrate on the side where the semiconductor laser device of the thermo module is arranged is the same as the optical fiber support member. Thermally independent from the substrate on the side where the semiconductor laser element of the thermo module is disposed via the optical fiber support member to the outside of the package. Claim 1 or claim 2 or claim 3 semiconductor laser module according to, characterized in that the release of the heat is limited. 5. A drive of a semiconductor laser module having a semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device, and an optical fiber optically coupled to laser light emitted from the semiconductor laser device. In the method, the thermo module changes a heating operation and a cooling operation in accordance with a direction of an energizing current, and variably adjusts a temperature of a semiconductor laser element in accordance with an amount of current applied to the thermo module. The thermo module is thermally connected to the semiconductor laser element, and a current path in the heating direction for heating the thermo module to flow through the thermo module is short-circuited between the upstream and downstream sides of the thermo module bypassing the thermo module. A bypass passage is provided, and a diode whose heating direction is a forward direction is provided in the bypass passage; In a state where the diode and a zener diode in the opposite direction are provided in series, the current in the heating direction is shunted to the bypass passage when the voltage across the zener diode exceeds a threshold value preset in the zener diode. A method for driving a semiconductor laser module, comprising suppressing overcurrent from flowing to a thermo module in a heating direction. 6. A semiconductor laser module comprising: a semiconductor laser device; a thermo module for adjusting a temperature of the semiconductor laser device; and an optical fiber optically coupled to laser light emitted from the semiconductor laser device. In the communication device, the thermo module changes a heating operation and a cooling operation according to a direction of an energizing current, and
The temperature of the semiconductor laser element is variably adjusted in accordance with the amount of current supplied to the thermomodule, and a current in a heating direction for heating the thermomodule is supplied to the thermomodule on a current path upstream of the thermomodule. A bypass path that short-circuits the downstream side and the thermo module is provided, and in this bypass path, a diode whose forward direction is the heating direction, and a Zener diode that is opposite to the diode are provided in series. The bypass path, the diode, and the Zener diode serve as overcurrent limiting means that causes a current in the heating direction to shunt and flow to the thermomodule and the bypass path, thereby suppressing overcurrent in the heating direction from flowing to the thermomodule. Communication equipment characterized by the following. 7. The communication device according to claim 6, wherein the overcurrent limiting means is provided in a power supply device of the semiconductor laser module.