JP2003304023A - Semiconductor laser module and method for driving the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress overenergizing current to a thermomodule. <P>SOLUTION: The thermomodule 5 performs heating operation when current in the direction from a lead pin 16f to a lead pin 16a flows, and performs cooling operation when the direction of the current is reversed. A semiconductor laser module comprises an overcurrent limiting means 20 connected in parallel with the thermomodule 5 to suppress the overcurrent in a heating direction of the thermomodule 5. The circuit of the means 20 is formed by interposing a diode 23 in a bypass passage 22 detoured at the thermomodule 5. The direction of the diode 22 is forward in the direction of the current in the heating direction, and a resistor 22 is connected in series with the diode 23. When the current of the heating direction is energized, the diode 23 becomes on, and the current is branched to the thermomodule 5 and the passage 21. The current quantity to the thermomodule 5 is reduced by this branching to suppress the overcurrent. <P>COPYRIGHT: (C)2004,JPO

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 and a method for driving the semiconductor laser module.

[0002]

2. Description of the Related Art FIG. 6 (a) is a sectional view schematically showing an example of the structure of a semiconductor laser module, and FIG. 6 (b) shows an example of the electrical wiring of the semiconductor laser module shown in FIG. 6 (a). It is shown. A semiconductor laser module 1 shown in FIG. 6A is a module in which a semiconductor laser element 2 and an optical fiber 3 are optically coupled.

That is, as shown in FIG. 6 (a), the thermo module 5 is provided on the inner bottom wall surface 4a of the package 4. The thermomodule 5 has a configuration in which a plurality of Peltier elements 5a are sandwiched by plate members 5b and 5c (first substrate, second substrate) made of a high thermal conductor (eg, aluminum nitride). In this example, the plate member 5b
Is fixed on the inner bottom wall surface 4a of the package 4, the heat radiation side of the Peltier element 5a is mounted on the plate member 5b by soldering, and the plate member 5 is attached on the heat absorption side of the Peltier element 5a.
c is fixed by solder.

In such a thermo module 5, the heat generating operation (heating operation) and the heat absorbing operation (cooling operation) change depending on the direction of the current flowing through the Peltier element 5a, and the heat generation amount and the heat absorption amount of the Peltier element are different. It changes according to the amount of current flowing through 5a.

On the upper side of the thermomodule 5 (that is, on the plate member 5c), a substrate 6 which is a component mounting member is soldered (for example, InPbAg eutectic solder (melting point 1)
It is fixedly installed at 48 ° C)). Support members 7 and 8 and a lens 9 are fixed to the upper side of the substrate 6. The support member 7 is provided with the semiconductor laser element 2 and a thermistor 10 for detecting the temperature of the semiconductor laser element 2. The support member 8 is provided with a monitoring photodiode 11 for monitoring the light emitting state of the semiconductor laser element 2. Examples of the semiconductor laser device 2 include a 1310 nm band and a 1
Signal light wavelength band of 550 nm band, 1480 nm band or 9
A wavelength band of pumping light of an optical fiber amplifier such as 80 nm band is generally used.

A through hole 4c is formed in the side wall 4b of the package 4, and the optical fiber supporting member 12 is formed in the through hole 4c.
Are fitted and installed. The optical fiber support member 12 has an insertion hole 12a, and the end portion side of the optical fiber 3 is introduced from the outside of the package 4 into the insertion hole 12a. A lens 14 is arranged inside the insertion hole 12a with a space from the tip of the optical fiber 3.

As shown in FIG. 6B, a plurality of lead pins 16 (14 in the example shown in FIG. 6B) are formed on the package 4 so as to project toward the outside. Also,
Inside the package 4, the semiconductor laser device 2, the thermomodule 5, the thermistor 10, and the photodiode 1 are provided.
Conducting means 17 such as a conductor pattern or a lead wire for electrically connecting 1 to the lead pin 16 is provided.
The semiconductor laser device 2, the thermomodule 5, and the thermistor 1 are connected by the conducting means 17 and the lead pin 16.
0 and the photodiode 11 can be electrically connected to drive control means (not shown) for driving the semiconductor laser module.

Specifically, in the example shown in FIG. 6B, the semiconductor laser device 2 is provided with the conducting means 17 and the lead pins 16 (16g, 16h), and the thermomodule 5 is provided with the conducting means 17 and the lead pins. 16 (16a,
16f), the thermistor 10 is conductively connected to the drive control means by the conducting means 17 and the lead pins 16 (16b, 16e), and the photodiode 11 is conductively connected to the drive control means by the conducting means 17 and the lead pins 16 (16c, 16d). It

The semiconductor laser module 1 shown in FIG. 6 is constructed as described above. When such a semiconductor laser module 1 is electrically 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, the semiconductor laser element 2 emits laser light. The emitted laser light is condensed by the coupling optical system composed of the lenses 9 and 14, enters the optical fiber 3, propagates in the optical fiber 3, and is used for a desired purpose.

By the way, the intensity and wavelength of the laser light emitted from the semiconductor laser element 2 vary depending on the temperature of the semiconductor laser element 2 itself. Therefore, in order to control the intensity and wavelength of the laser light to be constant, the drive control means controls the temperature of the semiconductor laser element 2 to be constant based on the output value output from the thermistor 10. The heating operation or the cooling operation of the thermo module 5 is controlled by controlling the direction and the amount of the energizing current of the module 5. By the temperature control by the thermo module 5, the semiconductor laser element 2 is kept 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]

[Patent Document 1] Japanese Patent Laid-Open No. 7-288351

[Patent Document 2] Japanese Patent Laid-Open No. 11-126939

[0012]

However, an abnormal situation may occur in which an overcurrent in the heating direction for heating the thermomodule 5 energizes the thermomodule 5 due to, for example, an operation error or the occurrence of an overvoltage. . In this case, the thermo module 5 is heated to an abnormally high temperature, and parts such as the semiconductor laser element 2, the substrate 6, the lens 9 and the like arranged on the thermo module 5 are rapidly (for example,
The thermistor 10 is heated suddenly such that the indicated temperature rises to 200 ° C. or higher in 10 seconds.

By the way, the plate member 5c of the thermomodule 5 is provided on the side wall of the package 4 and the optical fiber supporting member 12.
When it is thermally connected to, part of the heat generated from the thermo module 5 is radiated to the outside through the side wall of the package 4 and the optical fiber support member 12. Therefore, when the thermomodule 5 is heated to an abnormally high temperature as described above, part of the high-temperature heat is radiated from the thermomodule 5 to the outside 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. 6, the components on the thermomodule 5 and the side wall of the package 4 and the optical fiber support member 12 are in a thermally independent state. For this reason, the heat of the components on the thermo module 5 is transferred to the package 4
4 through the side wall of the optical fiber support member 12
There is almost no heat dissipation to the outside. In such a case, when abnormally high temperature heating of the thermo module 5 occurs, the high temperature heat of the thermo module 5 is transferred to and accumulated in the parts on the thermo module 5. For this reason, the temperature rise of the parts 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 thermomodule 5 caused by the overcurrent energization in the heating direction, defects inside the crystal of the semiconductor laser element 2 may occur. There is a problem that the semiconductor laser device 2 grows and the characteristics of the semiconductor laser device 2 are significantly deteriorated.

Further, the substrate 6 is fixed to the plate member 5c of the thermomodule 5 with solder (a hot-melt connection material) such as InPbAg eutectic solder (melting point 148 ° C.) as described above. Therefore, when the thermomodule 5 is heated to an abnormally high temperature as described above, the solder may melt and the substrate 6 may be displaced. Due to the positional displacement of the substrate 6, the semiconductor laser device 2 and the lens 9 are displaced from their normal positions, and the semiconductor laser device 2 and the lens 9 are displaced from the optical fiber 3 to cause optical coupling displacement (alignment displacement). The problem arises. In particular, when the semiconductor laser element 2 causes an angular displacement with respect to the optical fiber 3 due to the positional displacement of the substrate 6, for example, 0.2 °.
The optical output is significantly reduced, such that the optical output is reduced by 95% due to the angle deviation of.

Further, the glass lens 9 is adhered and fixed to, for example, a metal holder using a low melting point glass, and the lens-equipped metal holder 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 thermomodule 5 is abruptly abnormally heated, due to a large difference in the coefficient of thermal expansion between the glass and the metal, the joint portion (low melting glass) between the lens 9 and the metal holder may be affected. A crack will occur. Due to this crack, the lens 9 comes off the metal holder, and the optical coupling between the semiconductor laser element 2 and the optical fiber 3 is impaired.

Further, as described above, the Peltier element 5
Since a and the plate members 5b and 5c are joined by using solder, the abnormal heating of the thermo module 5 causes the solder to melt, and the thermo module 5 itself is damaged by, for example, the Peltier element 5a coming off. There is a risk of

The present invention has been made to solve the above problems, and an object thereof is to prevent overcurrent conduction in the thermomodule in the heating direction and to avoid the occurrence of problems due to the overcurrent conduction. It is an object of the present invention to provide a semiconductor laser module and a method for driving the semiconductor laser module that can perform the operation.

[0020]

In order to achieve the above object, the present invention has the following constitution as means for solving the above problems. That is, the semiconductor laser module of the first invention comprises a semiconductor laser device, a substrate for fixing the semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device via the substrate, and the semiconductor laser device. In a semiconductor laser module having an optical fiber optically coupled with the emitted laser light, and a package accommodating the semiconductor laser element and a thermo module, the substrate is placed on the thermo module via a heat fusion connecting material. The thermomodule is fixed, and is configured to variably adjust the temperature of the semiconductor laser element by changing the heating operation and the cooling operation according to the direction and the amount of current flowing through the thermomodule, and Overcurrent in the heating direction for heating the thermomodule in the package Flow the hot melt connection material is a means of solving the problem with a configuration in which the overcurrent limiting means prevents the melt.

The semiconductor laser module of the second invention is
According to the first aspect of the invention, the overcurrent limiting means is connected in parallel to the thermomodule and bypasses at least a part of a current in a direction in which an optical component fixed on the thermomodule is heated. Is configured to prevent overcurrent from flowing in the thermomodule.

A semiconductor laser module according to the third invention is
The thermomodule has the configuration of the first or second invention, and the thermomodule is configured by sandwiching a Peltier element between a first substrate and a second substrate, and either one of the first substrate and the second substrate is provided. A semiconductor laser element is disposed on the side and is thermally connected to a thermo module, and also has a lens for condensing the laser light emitted from the semiconductor laser element and introducing it into an optical fiber. The lens is configured to be thermally connected to the substrate on the side where the semiconductor laser element of the thermomodule is arranged, through the hot-melt connection material that fixes the mounting member of the lens. And

A semiconductor laser module according to the fourth invention is
The optical fiber is a lensed optical fiber having the configuration of the first or second invention, wherein the optical fiber has a lens for condensing the laser light emitted from the semiconductor laser element at the end where the laser light is incident. Is configured.

The semiconductor laser module of the fifth invention is
The thermomodule comprises the configuration of any one of the first to fourth inventions, and the thermomodule is configured by sandwiching a Peltier element between a first substrate and a second substrate. A semiconductor laser device is disposed on one side of the semiconductor laser device and is thermally connected to a thermo module, and the semiconductor laser device and the thermo module are housed in a package, and the package is provided in the package. Is provided with a through hole communicating from the inside to the outside, and an optical fiber support member made of a heat conductive material is fitted and mounted in the through hole, and an end portion of the optical fiber is inserted through an insertion hole provided in the optical fiber support member. Side is introduced from the outside of the package to the inside, and the substrate of the thermomodule on which the semiconductor laser element is arranged is thermally independent of the optical fiber supporting member. And characterized in that it has a structure in which the thermo-module of the semiconductor laser element from a substrate of the arrangement to the side of the heat to the outside of the package via the optical fiber supporting member release is limited.

The semiconductor laser module of the sixth invention is
A semiconductor laser device, a substrate for fixing the semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device through the substrate, and a laser beam emitted from the semiconductor laser device optically coupled. In a semiconductor laser module having an optical fiber and a package accommodating the semiconductor laser element and a thermomodule, the substrate is fixed on the thermomodule via a hot melt connecting material, and the thermomodule is the thermomodule. The heating operation and the cooling operation are changed according to the direction of the current flowing in the energization path of
A current is supplied to the energizing path in the cooling direction, and the cooling amount is adjusted according to the energizing amount to adjust the temperature of the semiconductor laser element to a constant temperature. The thermomodule is provided in parallel with the overcurrent limiting means. The overcurrent limiting means is provided with a bypass passage that bypasses the thermomodule and short-circuits the energization path at both ends of the thermomodule; and a current passage in the heating direction, which is interposed in the bypass passage, is defined as a forward direction. And the overcurrent limiting unit divides the overcurrent into the bypass passage when the overcurrent in the heating direction flows in the energizing path to suppress melting of the hot-melt connection material. It is characterized by

A seventh aspect of the present invention relates to a method for driving a semiconductor laser module, which includes a semiconductor laser element, a substrate for fixing the semiconductor laser element, and a temperature of the semiconductor laser element which is fixed to the substrate via a hot-melt connection material. In a method of driving a semiconductor laser module having a thermomodule to be adjusted and an optical fiber optically coupled with laser light emitted from the semiconductor laser element, a current for energizing the temperature of the semiconductor laser element to the thermomodule Is adjusted according to the direction and the amount of current, and an overcurrent limiting means for limiting an overcurrent in the heating direction that raises the temperature of the semiconductor laser element is provided in the current-carrying path of the current to the thermomodule. A structure is provided that suppresses melting of the hot-melt connection material by suppressing overcurrent conduction. The features.

In the invention of the above structure, the overcurrent limiting means suppresses the energization of the thermomodule to the overcurrent when the overcurrent is generated due to an operation error or an overvoltage. As described above, since the overcurrent conduction to the thermomodule is suppressed, it is possible to prevent the above-mentioned various problems caused by the overcurrent conduction to the thermomodule in the heating direction. As a result, the reliability of optical coupling and durability of the semiconductor laser module can be significantly improved.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION 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 of the first embodiment. A characteristic of the first embodiment is that an overcurrent limiting circuit 20 which is an overcurrent limiting unit (reverse current limiting unit) is provided as shown in FIG. The other structure is the same as that of the semiconductor laser module shown in FIG. 6, and in the description of the first embodiment, the structure shown in FIG.
The same components as those of the semiconductor laser module shown in FIG.

The semiconductor laser module 1 is often used in an environment of room temperature or higher, and it is often assumed that the thermo module 5 performs only the cooling operation. In the first embodiment, the thermo laser module 5 is used. In consideration of the case where the module 5 performs not only the cooling operation but also the heating operation, the following overcurrent limiting circuit 20 is provided inside the package 4.

That is, in the first embodiment, the overcurrent limiting circuit 20 is constructed to have the bypass passage 21, the resistor 22 and the diode 23.

In FIG. 1, one end of the bypass passage 21 is connected to a point X on the lead pin 16a side of the thermo module 5, and the other end of the bypass passage 21 is connected to a point Y on the lead pin 16f side of the thermo module 5. It is connected.

In the first embodiment, the lead pin 1
When a current flows in the direction from 6f to the lead pin 16a, the thermomodule 5 performs a heating operation, and
On the contrary, the thermomodule 5 is configured to perform the cooling operation when the current is applied in the direction from the lead pin 16a to the lead pin 16f. From this,
In other words, the bypass passage 21 is connected to the thermomodule 5 in the heating current path to the thermomodule 5.
The upstream side Y and the downstream side X are short-circuited by bypassing the thermo module 5.

A resistor 22 is provided in the bypass passage 21, and a diode 23 having a forward heating current direction for heating the thermomodule 5 is provided in series with the resistor 22.

The semiconductor laser module 1 shown in the first embodiment is constructed as described above. less than,
A circuit operation example of the overcurrent limiting circuit 20 will be briefly described. For example, the semiconductor laser module 1 is conductively connected to the drive control means for driving the semiconductor laser module by using the lead pin 16. In this state, when the drive control means supplies the current in the direction from the lead pin 16a to the lead pin 16f, that is, the current in the cooling direction for cooling the thermomodule 5, the overcurrent limiting circuit 20 operates. The diode 23 is turned off. As a result, all the current in the cooling direction flows into the thermo module 5 without energizing the bypass passage 21.

On the contrary, a 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. As a result, the current in the heating direction depends on the ratio of the resistance value of the thermo module 5 to the resistance value of the resistor 22 and the thermo module 5 and the bypass passage 21.
Divide into and energize.

When an overcurrent in the heating direction is generated, the overcurrent is divided into the thermomodule 5 and the bypass passage 21 and flows as described above. As a result, compared with the case where all of the above-mentioned overcurrent is energized to the thermomodule 5, it is possible to mitigate overcurrent energization to the thermomodule 5. The resistance value of the resistor 22 is appropriately set according to the specifications.

In the first embodiment, as described above, the substrate (the plate member (here, the plate member 5c)) on the side where the semiconductor laser device of the thermo module 5 is arranged is the side wall of the package 4 or the optical device. It is thermally independent of the fiber support member 12. Therefore, when an overcurrent in the heating direction is applied to the thermomodule 5, the heat of high temperature heating of the thermomodule 5 caused by the overcurrent application is passed through the side wall of the package 4 and the optical fiber support member 12 to the package 4 Is not radiated to the outside, but is accumulated in the components on the thermo module 5 and various problems due to overcurrent conduction in the heating direction are likely to occur.

On the other hand, in the first embodiment, the overcurrent limiting circuit 20 is provided and the overcurrent limiting circuit 20 is provided.
With this configuration, since the overcurrent energization in the heating direction to the thermo module 5 is relaxed, various problems caused by the overcurrent energization in the heating module 5 can be avoided.

That is, abnormal heating of the thermo module 5 due to overcurrent conduction in the heating direction can be suppressed,
This can prevent the semiconductor laser element 2 from being heated to a high temperature. Therefore, it is possible to prevent the growth of defects inside the crystal of the semiconductor laser element 2 due to high temperature heating, and prevent the characteristic deterioration of the semiconductor laser element 2.

Further, the heat-melting connection material such as solder for connecting the substrate 6 which is a member for mounting the semiconductor laser element 2 and the lens 9 and the like to the thermomodule 5 is melted due to the high temperature heating of the thermomodule 5. It is possible to avoid this, and thus it is possible to prevent the displacement of the substrate 6. As a result, the positional displacement of the semiconductor laser element 2 and the lens 9 with respect to the optical fiber 3 can be avoided, the occurrence of the optical coupling deviation between the optical fiber 3 and the semiconductor laser element 2 can be suppressed, and the reduction of the optical output can be prevented.

Furthermore, 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 of the thermo module 5. As a result, it is possible to prevent the lens 9 from coming off due to the occurrence of cracks, and it is possible to avoid a situation in which the optical coupling between the semiconductor laser element 2 and the optical fiber 3 is impaired.

Further, the Peltier element 5a and the plate member 5b,
Since the melting of the solder between 5c can be prevented, the damage of the thermo module 5 itself can be avoided.

As described above, by providing the overcurrent limiting circuit 20 which is characteristic in the first embodiment, various problems caused by the overcurrent conduction in the heating direction to the thermomodule 5 can be prevented. You can As a result, the reliability of optical coupling and durability of the semiconductor laser module 1 can be significantly improved.

The second embodiment will be described below. The characteristic of the second embodiment is different from that of the first embodiment, as shown in FIG.
That is, the capacitor 25 for energizing the surge current is provided in parallel. The rest of the configuration is the same as that of the first embodiment, and in the description of this second embodiment, the first embodiment will be described.
The same components as those of the embodiment example are designated by the same reference numerals, and duplicate description thereof will be omitted.

In the second embodiment, since the capacitor 25 is provided in parallel with the thermomodule 5 as described above, when a surge current, which is a large instantaneous current, occurs, the surge current is The capacitor 25 is energized and the thermomodule 5 is not energized. As a result, it is possible to prevent damage to the thermo module 5 due to the energization of the surge current.

That is, the surge current has a high frequency, and the impedance of the capacitor becomes smaller as the frequency becomes higher. Therefore, even if the surge current is generated and the thermomodule 5 is energized,
Most of the surge current will flow into the capacitor 25. As a result, it is possible to suppress the surge current from being applied to the thermo module 5, and it is possible to prevent the problem of damage to the thermo module 5 due to the supply of 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 momentarily rise in temperature, causing various problems as described above. However, this second embodiment example Then, as described above, since the surge current conduction to the thermo module 5 is suppressed by the capacitor 25, the characteristic deterioration problem of the semiconductor laser device 2 and the semiconductor laser device 2 as described above are suppressed.
It is possible to prevent various problems such as the problem of optical coupling deviation of the optical fiber 3 and the problem of optical coupling being lost due to the lens 9 coming off.

According to this second embodiment, the first
Since the overcurrent limiting circuit 20 is provided as in the first embodiment, the overcurrent conduction in the heating direction to the thermomodule 5 is performed by the overcurrent limiting circuit 20 as in the first embodiment. Can be suppressed, and various problems due to overcurrent conduction in the heating direction can be prevented. Moreover, since the capacitor 25 is provided in parallel with the thermomodule 5 as described above, the capacitor 25 can prevent the occurrence of problems due to the surge current energization.

The present invention is not limited to the above embodiments, but various embodiments can be adopted. For example, in each of the above-described embodiments, in consideration of the fact that the semiconductor laser module 1 is used not only in an environment at room temperature or higher, but also in a low temperature environment lower than room temperature, the thermomodule 5 is not limited to the cooling operation. It is assumed that the heating operation is also performed. Therefore, the resistor 22 is provided in the bypass passage 21 in order to supply the heating module 5 with the current in the heating direction. However, for example, when it is assumed that the semiconductor laser module 1 is used in an environment at room temperature or higher, that is, when the thermo module 5 is assumed to perform only the cooling operation, the resistor 22 is not provided. Good.

In this case, almost all of the current in the heating direction is passed through the bypass passage 21 and is hardly passed through the thermomodule 5. As a result, it is possible to reliably prevent an overcurrent in the heating direction from being applied to the thermomodule 5. As a result, the thermo module 5
It is possible to more reliably avoid the occurrence of various problems as described above due to the overcurrent energization in the heating direction.

Further, when it is assumed that the thermomodule 5 performs only the cooling operation in the same manner as described above, it is not necessary to supply a current in the heating direction to the thermomodule 5.
Instead of providing the bypass passage 21, a diode whose cooling current direction is the forward direction may be provided in series with the thermo module 5. In other words, the diode may be configured to block all current flow in the heating module 5 in the heating direction.

In each of the above embodiments, the overcurrent limiting circuit 20 is provided in the package 4, and the example of the semiconductor laser module with the overcurrent limiting function is shown.
For example, as shown in FIG. 3, between the semiconductor laser module 1 having the same structure as the conventional one and the drive control means for the semiconductor laser module, a bypass passage 21 surrounded by a dotted line in FIG. An overcurrent limiting circuit 20 including a resistor 22 and a diode 23 may be provided to drive the semiconductor laser module. Furthermore, similarly,
A capacitor 25 similar to that shown in the second embodiment.
Alternatively, it may be provided outside the semiconductor laser module 1 as shown by the chain line in FIG. The overcurrent limiting circuit 20 and the capacitor 25 provided outside the semiconductor laser module 1 shown in FIG. 3 perform the same functions as the overcurrent limiting circuit 20 and the capacitor 25 shown in each of the above embodiments, and each of the above embodiments. The same effect as the example can be obtained.

Further, in each of the above embodiments, FIG.
As shown in FIG. 4A, the coupling optical system is formed by using the lenses 9 and 14 which are separate from the optical fiber 3.
As shown in FIG. 3, the coupling optical system may be formed by using the optical fiber with lens 3 without using the lenses 9 and 14. The lens-attached optical fiber 3 is an optical fiber provided with a lens 3a for condensing the laser light emitted from the semiconductor laser element 2.

The lens-attached optical fiber 3 is incorporated in the semiconductor laser module 1 as shown below. For example, as shown in FIG. 4, 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 the c
It is fixed by a bonding material 30 such as solder. The optical fiber support members 28 and 29 are respectively provided with through holes, and the optical fiber 3 is introduced into the package 4 from the outside through the through holes, and the tip of the optical fiber 3 and the semiconductor laser element 2 are separated from each other. They are arranged with an appropriate interval for optical coupling. The configuration other than the above is the same as the configuration shown in FIG. 6A, and the duplicated description will be omitted here.

The optical fiber support members 28 and 29 are made of a heat conductive material such as Fe-Ni-Co alloy. In the configuration shown in FIG. 4, the substrate (that is, the plate member 5c) on the side where the semiconductor laser element 2 is arranged in the thermo module 5 is strictly thermally connected to the optical fiber support member 29 through the optical fiber 3. There is. However, since the optical fiber 3 has a small diameter of, for example, about 125 μm, the amount of heat transferred from the plate member 5c of the thermomodule 5 to the optical fiber support member 29 through the optical fiber 3 is very small.

As a result, the plate member 5c of the thermomodule 5 is the same as being thermally independent of the optical fiber support member 29. That is, in the configuration shown in FIG.
The heat radiation from the plate member 5c of the thermo module 5 to the outside of the package 4 via the optical fiber supporting member 29 is restricted. In such a configuration, as described above, when the thermomodule 5 is abnormally heated to a high temperature due to the overcurrent conduction to the thermomodule 5, the high-temperature heat is accumulated in the components on the thermomodule 5. Various problems arise. On the other hand, by providing a configuration for suppressing overcurrent conduction to the thermomodule 5 as shown in each of the above embodiments, the thermomodule 5
Can prevent problems caused by overcurrent energization to
It is very effective.

Further, as an application example of the present invention, a structure as shown in FIG. 5 may be adopted. In the example shown in FIG. 5, the thermomodule 5 is controlled not by current control but by voltage control, and it is possible to avoid the occurrence of a problem caused by applying an overvoltage to the thermomodule 5. That is, in FIG. 5, the overvoltage limiting means 31 is provided in series with the thermomodule 5. The above-mentioned overvoltage limiting means 31
Is a diode 32 whose forward direction is the cooling direction.
And a resistor 33 in parallel connection.

In the configuration shown in FIG. 5, when the voltage in the cooling direction is applied to the thermo module 5, the diode 3
2 is in a conduction ON state, and almost no current flows through the resistor 33, but almost all flows through the diode 32. As a result, almost all the voltage applied between the lead pins 16a and 16f is applied to the thermo module 5.

On the other hand, when the voltage in the heating direction is applied to the thermo module 5, the diode 32 is turned off and the current flows to the resistor 33.
The voltage applied between the lead pins 16a and 16f is divided and applied to the thermo module 5 and the resistor 33. Therefore, when an overvoltage is generated between the lead pins 16a and 16f, the overvoltage is generated by the thermomodule 5
Then, the voltage is divided and applied to the resistor 33. Therefore, the overvoltage application to the thermo module 5 can be mitigated, and the problem caused by the overvoltage application to the thermo module 5 can be prevented. Such overvoltage limiting control and overcurrent limiting means as shown in each of the above embodiments may be provided together.

[0060]

According to the semiconductor laser module and the method for driving the semiconductor laser module of the present invention, the overcurrent limiting means for suppressing the overcurrent in the heating direction of the semiconductor laser module is provided, and the thermomodule is provided by the overcurrent limiting means. It is configured to suppress overcurrent conduction to the. With this configuration, it is possible to avoid various problems caused by abnormally high temperature heating due to overcurrent conduction to the thermomodule.

In the case where the overcurrent limiting means is provided on the current path for flowing the current in the heating direction for heating the thermomodule to the thermomodule, the overcurrent limiting means causes the overcurrent in the heating direction to the thermomodule. Can be suppressed. When an overcurrent in the heating direction is applied to the thermomodule, the thermomodule is heated to an abnormally high temperature and causes various problems. On the other hand, as described above, by providing the overcurrent limiting device to suppress the overcurrent in the heating direction, various problems caused by the overcurrent conduction in the heating module to the thermomodule are prevented. You can In other words, it prevents the problem of characteristic deterioration of the semiconductor laser device due to abnormal heating of the thermomodule, the problem of optical coupling deviation due to melting of the hot-melt bonding material, the problem of optical coupling loss due to lens detachment, and the problem of thermomodule damage. be able to.

When the overcurrent limiting means has the bypass passage, the overcurrent conduction to the thermomodule can be suppressed with a simple structure.

The substrate of the thermomodule on which the semiconductor laser device is arranged is thermally independent of the optical fiber supporting member, and heat from the substrate of the thermomodule to the outside of the package via the optical fiber supporting member. In the case of limited emission, the high temperature heat generated from the thermo module is not radiated to the outside of the package when an overcurrent is applied to the thermo module in the heating direction. Heat may be transferred to and accumulated in parts such as semiconductor laser devices that are thermally connected to the module, causing a rapid temperature rise of the parts, and causing various serious situations such as melting of the hot-melt connection material. There is. By providing an overcurrent limiting means characteristic of the present invention in such a configuration, it is possible to suppress overcurrent conduction in the heating direction to the thermomodule, thereby preventing the occurrence of the serious situation. It can be prevented and is very effective.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram showing an example of electrical wiring of a semiconductor laser module, which is a characteristic of the second embodiment.

FIG. 3 is an explanatory diagram showing another embodiment example.

FIG. 4 is an explanatory diagram showing another embodiment example.

FIG. 5 is an explanatory diagram showing another embodiment example.

FIG. 6 is an explanatory view showing one structural example of a semiconductor laser module and a conventional electrical wiring example of the semiconductor laser module.

[Explanation of symbols]

1 Semiconductor laser module 2 Semiconductor laser device 3 optical fiber 4 packages 5 Thermo module 9,14 lens 12,29 Optical fiber support member 20 Overcurrent limiting means 21 Bypass passage 22 resistor 23 Diode 25 capacitors

Claims (7)

[Claims] 1. A semiconductor laser device, a substrate for fixing the semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device via the substrate, and a laser beam emitted from the semiconductor laser device and an optical device. In a semiconductor laser module having an optically coupled optical fiber and a package accommodating the semiconductor laser element and a thermo module, the substrate is fixed on the thermo module via a hot melt connecting material, The module is configured to variably adjust the temperature of the semiconductor laser element by changing the heating operation and the cooling operation in accordance with the direction and amount of the current supplied to the thermomodule, and the thermomodule in the package. An overcurrent in the heating direction that causes the heating operation flows to melt the hot-melt connection material. A semiconductor laser module comprising an overcurrent limiting means for suppressing the above. 2. The overcurrent limiting means is connected to the thermomodule in parallel, and bypasses at least a part of a current in a direction in which an optical component fixed on the thermomodule is heated to the thermomodule. 2. An overcurrent is prevented from flowing.
The described semiconductor laser module. 3. The thermo module comprises a Peltier element as the first element.
Is sandwiched between the first substrate and the second substrate, and the semiconductor laser element is disposed on either one of the first substrate and the second substrate and is thermally connected to the thermomodule. A lens for condensing the laser light emitted from the semiconductor laser element and introducing it into an optical fiber, the lens being a thermo-melting connection material through which a fixing member of the lens is fixed. The semiconductor laser module according to claim 1 or 2, wherein the semiconductor laser module is configured to be thermally connected to a substrate on a side where the semiconductor laser element of the module is arranged. 4. The optical fiber with a lens, wherein a lens for condensing the laser light emitted from the semiconductor laser element is formed at an end portion where the laser light is incident. The semiconductor laser module according to claim 2. 5. The thermomodule comprises a Peltier element as the first element.
Is sandwiched between the first substrate and the second substrate, and the semiconductor laser element is arranged on either one of the first substrate and the second substrate and is thermally connected to the thermomodule. The semiconductor laser device and the thermo module are housed and arranged in a package, the package is provided with a through hole communicating from the inside of the package to the outside, and the through hole has an optical fiber made of a heat conductive material. A support member is fitted and mounted, and an end portion side of the optical fiber is introduced into the inside from the outside of the package through an insertion hole provided in the optical fiber support member, and a substrate on the side where the semiconductor laser element of the thermomodule is arranged. Is thermally independent of the optical fiber supporting member, and supports the optical fiber from the substrate on the side where the semiconductor laser device of the thermomodule is arranged. The semiconductor laser module according to any one of claims 1 to 4 characterized in that release of heat to the outside of the package through the wood is restricted. 6. A semiconductor laser device, a substrate for fixing the semiconductor laser device, a thermo module for adjusting the temperature of the semiconductor laser device via the substrate, and a laser beam emitted from the semiconductor laser device and an optical device. In a semiconductor laser module having an optically coupled optical fiber and a package accommodating the semiconductor laser element and a thermo module, the substrate is fixed on the thermo module via a hot melt connecting material, The module is configured to change the heating operation and the cooling operation in accordance with the direction of the current flowing in the energizing path of the thermomodule, and apply a current in the cooling direction to the energizing path,
The temperature of the semiconductor laser device is adjusted to a constant temperature by adjusting the cooling amount in accordance with the amount of energization, and the thermomodule is provided with overcurrent limiting means in parallel. A bypass passage that bypasses the thermomodule and short-circuits the current-carrying path on both sides of the thermomodule, and a diode that is interposed in the bypass passage and that directs the current in the heating direction to the forward direction. A means for suppressing the melting of the hot melt connecting material by diverting the overcurrent to the bypass passage when an overcurrent in the heating direction flows in the energizing path. 7. A semiconductor laser device, a substrate for fixing the semiconductor laser device, a thermo module fixed to the substrate through a heat-melting connection material for adjusting the temperature of the semiconductor laser device, and the semiconductor laser device. In a method of driving a semiconductor laser module having an optical fiber optically coupled with the emitted laser light, the temperature of the semiconductor laser element is adjusted according to the direction and amount of current flowing through the thermomodule, An overcurrent limiting unit that limits an overcurrent in the heating direction that raises the temperature of the semiconductor laser element is provided in a current passage of the current to the thermomodule to suppress the overcurrent conduction to the thermomodule. A method for driving a semiconductor laser module, which is characterized by suppressing melting of a connecting material.