JPH0662560U - Semiconductor laser device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent abnormal temperature rise of the laser diode module. [Structure] In addition to the first heat sink 16 closely fixed to the laser diode module 1, a second heat sink 22 separate from the first heat sink 16 is provided. Then, by using the second cooling element 21 sandwiched between the two, the first heat sink 16 is forcibly deprived of heat and radiated to the second heat sink 22 side. The first heat sink 16 is
The temperature is maintained at a substantially stable temperature due to a sudden rise in the outside air temperature and the like, and the laser diode module 1 closely fixed to the temperature is also maintained at a constant appropriate temperature. Therefore, even if the first cooling element 8 inside the laser diode module 1 is driven when the outside air temperature is high, there is no possibility that the temperature of the entire module will rise.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a semiconductor laser device having a cooling function for thermally protecting a laser diode widely used in the field of optical communication for converting an electric signal into an optical signal.

[0002]

[Prior art]

 Semiconductor laser devices are widely used in the fields of optical communication and the like, and are used for converting electric signals into optical signals and inputting them into optical fibers or the like. FIG. 2 shows a schematic view of a main part of a laser diode module used for such an application. An optical fiber 3 is connected to the laser diode module 1 via a connector 2. A laser diode 4 is provided to input an optical signal to the optical fiber 3. In addition, a light receiving element 5 for monitoring an optical signal, an isolator 6 used for coupling an optical signal between the laser diode 4 and the connector 2 and the like are housed inside the module.

When the laser diode module 1 having such a configuration is driven, the laser diode 4 emits light by a signal current, and the light is transmitted through the optical fiber 3. However, during this light emission, the laser diode 4 generates heat due to the signal current. Usually, the laser diode module 1 has a hermetically sealed structure in order to prevent the entry of foreign matter. Therefore, if the laser diode 4 generates heat, the temperature of the laser diode 4 itself rises. The usable temperature of the laser diode 4 is determined, and if the temperature rises abnormally, the characteristics of the laser diode 4 deteriorate, and eventually the laser diode 4 is damaged. Therefore, conventionally, a thermistor 7 for temperature detection and a cooling element 8 for cooling are built in the laser diode module 1 to forcibly cool the inside of the laser diode module 1. There is. A Peltier element or the like is adopted as the cooling element 8.

FIG. 3 shows a schematic diagram of a semiconductor laser device including the above laser diode module and a circuit for cooling control thereof. As shown in the figure, a cooling control unit 10 is provided outside the laser diode module 1 for cooling control of the laser diode module 1. The cooling control unit 10 includes a temperature detection unit 11, a reference value setting unit 12, a comparison unit 13, and a cooling element drive unit 14.

The temperature detection unit 11 is a unit that receives the output signal of the thermistor 7 shown in FIG. 2 and detects the temperature of the laser diode module 1 by the signal. It consists of a load resistor that converts the signal current into a voltage. The reference value setting unit 12 is a circuit that outputs a signal corresponding to the reference temperature in order to keep the laser diode 4 shown in FIG. 2 at the set temperature, and is composed of a variable resistor or the like. The comparison unit 13 is composed of a differential amplifier or the like that compares the voltage signals output from the temperature detection unit 11 and the reference value setting unit 12 and outputs a signal corresponding to the difference. The cooling element drive unit 14 is composed of a voltage-current conversion circuit or the like that outputs a current for driving the cooling element 8 shown in FIG. 2 according to the output signal of the comparison unit 13.

When the cooling element 8 is driven inside the laser diode module 1, one end of the cooling element 8 absorbs heat from the laser diode 4 and the other end radiates heat. In order to dissipate this heat to the outside, the laser diode module 1 is fixed so as to be in direct contact with the heat sink 16 composed of an aluminum plate or the like.

[0007]

[Problems to be solved by the device]

 By the way, also in the CATV system (television joint viewing system) and the like, an optical cable is used for relaying a broadcast signal. In this system, a semiconductor laser device is also incorporated in a CATV repeater or the like installed outdoors. However, when the above semiconductor laser device is incorporated in a repeater suspended and fixed to a utility pole or the like, conventionally, the following problems to be solved have occurred in controlling the temperature thereof.

FIG. 4 shows a temperature characteristic diagram of the semiconductor laser device. CATV repeaters are exposed to direct sunlight outdoors during the day. Therefore, the temperature around the semiconductor laser device also rises rapidly as the outside air temperature rises. Similarly, the temperature of the heat sink 16 itself shown in FIG. 3 also rises. This FIG. 4 is a graph in which the vertical axis represents temperature and the horizontal axis represents time. Here, the temperature TL of the laser diode is controlled so as to be maintained at the preset temperature T1 in advance. At this time, for example, when the outside air temperature TS gradually rises due to direct sunlight or the like, the temperature of the heat sink 16 shown in FIG. 3 also rises, and the temperature TM of the laser diode module 1 in close contact with the heat sink 16 also rises.

On the other hand, the isolator 6 and the like housed in the laser diode module 1 as shown in FIG. 2 are composed of a lens system for guiding the light emitted by the laser diode 4 to the optical fiber 3. Therefore, precise mechanical characteristics are required, and there is a possibility that reliability and performance may deteriorate due to an abnormal temperature rise in the entire laser diode module. The present invention has been made in view of the above points, and an object thereof is to provide a semiconductor laser device configured to prevent an abnormal temperature rise of the laser diode module itself as described above.

[0010]

[Means for Solving the Problems]

 The semiconductor laser device of the present invention comprises a laser diode, a laser diode module containing a first cooling element for cooling the laser diode, and the first cooling element for maintaining the laser diode at a preset temperature. A first cooling control section for controlling the heat sink, a first heat sink closely adhered to the laser diode module, a second heat sink separated from the first heat sink, and a first heat sink. The second cooling element, which is sandwiched between the second heat sinks and closely adhered to them, absorbs heat from the first heat sink and releases the heat to the second heat sink side, and the laser diode at a set temperature. And a second cooling control section for controlling the second cooling element so as to keep the above.

[0011]

[Action]

 In this semiconductor laser device, in addition to the first heat sink closely fixed to the laser diode module, a second heat sink that is separate from the first heat sink is provided. Then, by using the second cooling element sandwiched between the two, the first heat sink is forcibly deprived of heat and radiated to the second heat sink side. As a result, the first heat sink is maintained at a substantially stable temperature due to a sudden rise in the outside air temperature and the like, and the laser diode module closely fixed to the first heat sink is also maintained at a constant appropriate temperature. Therefore, even if the first cooling element inside the laser diode module is driven when the outside air temperature is high, there is no possibility that the temperature of the entire module will rise.

[0012]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. FIG. 1 is an external perspective view showing an embodiment of a semiconductor laser device of the present invention. As shown in this figure, in the semiconductor laser device of the present invention, the first heat sink 16 is closely fixed to the laser diode module 1 as described above with reference to FIG. In addition to 16, a second heat sink 22 is further provided. The configurations of the laser diode module 1 and the first heat sink 16 are the same as those of the conventional one as already described with reference to FIG. Further, in order to drive the first cooling element 8 provided inside the laser diode module 1, a first cooling controller 10 having the same configuration as that shown in FIG. 3 is provided.

The laser diode module 1 is also connected to the connector 2 and the optical fiber 3 as described with reference to FIGS. 2 and 3, and is configured to guide the light of the laser diode (not shown) to the outside. . Here, in the device of the present invention, as described above, the second heat sink 22 is provided in addition to the first heat sink 16. As the second heat sink 22, a case for accommodating the semiconductor laser device, or another suitable large-sized substrate made of metal is used.

A second cooling element 21 is arranged and sandwiched between the first heat sink 16 and the second heat sink 22 so as to be in close contact with both. The second cooling element 21 is composed of a Peltier element, and its heat absorbing side surface is in close contact with the first heat sink 16 and its heat radiating side surface is in close contact with the second cooling element 22. A second cooling controller 20 is provided to drive the second cooling element 21, and a thermistor 23 for temperature control is fixed to the side surface of the laser diode module 1. The configuration of the second cooling control unit 20 is completely the same as that of the first cooling control unit 10, and the illustration and description of the internal circuit thereof are omitted because they are duplicated.

FIG. 5 shows a temperature characteristic explanatory diagram of the semiconductor laser device as described above. Similar to FIG. 4, this figure is a graph in which time is plotted on the horizontal axis and temperature is plotted on the vertical axis. Here, it is assumed that the temperature TL of the laser diode (not shown) used inside the laser diode module 1 shown in FIG. 1 is set to the temperature T1 as shown in the figure, for example. This temperature setting is performed by the first cooling controller 10. On the other hand, in the present invention, the temperature of the main body of the laser diode module 1 is set to the temperature T2 in advance, for example. This temperature setting is performed by the second cooling control unit 20.

When the first cooling control unit 10 and the second cooling control unit 20 shown in FIG. 1 are driven with the above settings, the outside air temperature TS gradually rises as shown in FIG. 5, for example. Even if it does, not only the temperature of the laser diode but also the temperature of the laser diode module 1 is maintained within a certain range of temperature. That is, in the laser diode module 1 shown in FIG. 1, the laser diode is cooled by the first cooling element as shown in FIG. 2, and the heat is radiated to the first heat sink 16. Conventionally, this has caused the temperature of the first heat sink 16 to gradually rise, but in the present invention, the second cooling element 21 draws heat from the first heat sink 16, and the heat is absorbed by the second heat sink 22. Dissipate heat to. The second cooling control unit 20 measures the temperature of the laser diode module 1 by the thermistor 23 and drives the second cooling element 21 so that the temperature becomes the set temperature T2. As a result, the first heat sink 16 is maintained at a temperature close to the set temperature T2, and has a temperature within a substantially constant range regardless of the rise in the outside air temperature.

As a result, abnormal temperature rises are prevented even with respect to other components such as the isolator other than the laser diode housed inside the laser diode module 1, and the reliability and performance of the entire module are stabilized. Can be planned. The present invention is not limited to the above embodiments. In the above embodiment, the laser diode module 1 is closely fixed to the relatively large first heat sink 16 and then fixed to another second heat sink via the second cooling element 21. However, by adopting the following configuration, the first heat sink 16 can be made sufficiently smaller than the conventional one.

FIG. 6 is a perspective view of an embodiment when the first heat sink is downsized. As shown in the figure, in this embodiment, a first heat sink 16-1 having substantially the same size as the laser diode module 1 is attached to the bottom surface of the laser diode module 1. In this way, the first heat sink 16-1 is integrated with the laser diode module 1, and the first heat sink 16-1 is connected to the first heat sink 16-1 via the second cooling element 21 including a Peltier element or the like. The second heat sink 22-1 is connected and fixed.

In the semiconductor laser device of the present invention, when the first cooling element 8 housed inside the laser diode module 1 cools the laser diode, the first heat sink that can maintain its heat radiation operation. Should be provided. The temperature rise of the first heat sink is suppressed by the second cooling element 21 and the second heat sink 22-1. Therefore, the configuration as shown in FIG. 2 can be used to reduce the size and simplify the configuration as a whole.

[0020]

[Effect of device]

 In the semiconductor laser device of the present invention described above, the laser diode module is adhered and fixed to the first heat sink, and the first cooling element housed inside the laser diode module cools the laser diode module, while the first A second heat sink that is separate from the heat sink is provided, and the first heat sink is sandwiched between the first heat sink and the second heat sink. Since the laser diode module is cooled and the laser diode module is maintained at the set temperature, not only the laser diode but also the entire laser diode module can be maintained within a certain temperature range. As a result, various components housed inside the laser diode module can be kept in a constant temperature range regardless of the rise in outside air temperature, and reliability and performance can be stabilized.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a semiconductor laser device of the present invention.

FIG. 2 is a schematic view of a main part of a laser diode module.

FIG. 3 is a schematic view of a conventional semiconductor laser device.

FIG. 4 is a diagram illustrating temperature characteristics of a conventional semiconductor laser device.

FIG. 5 is an explanatory diagram of temperature characteristics of the semiconductor laser device of the present invention.

FIG. 6 is a perspective view of a modified example of the semiconductor laser device of the present invention.

[Explanation of symbols]

 1 Laser Diode Module 3 Optical Fiber 8 First Cooling Element 10 First Cooling Control Section 16 First Heat Sink 20 Second Cooling Control Section 21 Second Cooling Element 22 Second Heat Sink

Claims (1)

[Scope of utility model registration request] 1. A laser diode module containing a laser diode and a first cooling element for cooling the laser diode; and a first cooling element for controlling the first cooling element so as to keep the laser diode at a preset temperature. No. 1 cooling control unit, and the first fixedly attached to the laser diode module.
A heat sink, a second heat sink separated from the first heat sink, a first heat sink and a second heat sink sandwiched between the first heat sink and the second heat sink, and the first heat sink and the second heat sink. A second cooling element that absorbs heat from a heat sink and radiates heat to the second heat sink side, and a second cooling control unit that controls the second cooling element to keep the laser diode at a set temperature are provided. Characteristic semiconductor laser device.