JPS6214759Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for cooling an electro-optical conversion element of an optical repeater.

In recent years, optical communication systems using optical fibers are being put into practical use, and various problems are being investigated. Among these various problems,
The present invention describes a light emitting device for generating optical signals. Specifically, this light emitting element is an electrical-to-optical conversion element, and after each optical repeater converts the optical signal received via the optical fiber cable into an electrical signal, it is amplified, equalized, and identified and reproduced for reproduction. It is an important element used when converting the processed electrical signal into an optical signal and retransmitting it to the optical fiber cable. Generally, a semiconductor laser diode, a light emitting diode, etc. are used as this electro-optical conversion element. These electro-optical conversion elements are small,
It has several excellent features such as high efficiency, low cost, and easy direct modulation. However, its reliability is still not sufficient, and it must be said that the reliability of semiconductor laser diodes in particular is extremely low. The current model has an estimated lifespan of tens of thousands of hours at room temperature (time when the light output level becomes 1/2), or 70 hours.
It has a short lifespan of several thousand hours at ℃. Currently at room temperature
There are reports of 1 million hours, but even in this case the temperature is 70℃.
It is thought that it will take several 100,000 hours or less.

On the other hand, considering that optical repeaters are installed on pillars or in manholes, the temperature around the electrical-to-optical conversion elements used therein is expected to reach 60 to 70 degrees Celsius at worst. Under such worst-case conditions,
The life of the electrical-to-optical conversion element becomes extremely short, and the reliability of the optical repeater and, ultimately, the reliability of the optical communication system is extremely reduced. Therefore, in an optical communication system, which has excellent advantages such as a spatial multiplicity greater than other transmission media due to the small diameter of the optical fiber itself and no influence from electromagnetic dielectricity, these advantages can be fully utilized. In order to
One of the important issues is to substantially increase the lifetime of the above-mentioned electro-optical conversion element.

Therefore, it is an object of the present invention to propose a cooling device for an electro-optical conversion element that substantially increases the life of the electro-optical conversion element.

In accordance with the above-mentioned objective, the present invention focuses on the fact that optical repeaters are generally supplied with power from a feeder line that is laid in parallel with an optical fiber cable, and by extracting power from the feeder line, the present invention More specifically, in optical repeaters that are powered by constant current, low impedance electricity that has almost no effect on the constant current power supply even if directly inserted into the constant current power supply line. The cooling means is characterized by using a heat conversion element, for example, an electro-thermal conversion element having a Peltier effect.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a block diagram for explaining a general power supply method in an optical communication system. In this figure, 11 and 12 are terminal stations, and terminal station 11
A large number of optical repeaters 14 are inserted at predetermined intervals into the optical fiber cable 13 that is wired between the optical fiber cable 13 and the optical fiber cable 12 . A data optical signal or audio optical signal sent from the terminal station 11 is once converted into an electrical signal in each optical repeater 14, and after processing such as amplification, equalization, identification and reproduction, etc., it is converted back into an optical signal. , is sent out to the optical fiber cable 13. An electrical-to-optical conversion element (not shown), which is the object of the present invention, performs the conversion into an optical signal. As described above, various electrical processes are performed within each optical repeater 14, so power supply for that purpose is required.
For this power supply, constant current power supply from the terminal station, constant voltage power supply, or local power supply for each optical repeater is possible, but it is possible to minimize the variation in the voltage used by each optical repeater. Constant current power feeding is common, and is carried out by a constant current power feeding device shown at 15 in FIG. The constant current I from the constant current power supply device 15 is passed through the power supply line 16 to each optical repeater 1.
It is divided into 4. This distribution is performed by a voltage generating circuit 17 inserted into the power supply line 16. The voltage generating circuit 17 is usually composed of a Zener diode, and a voltage is applied to each optical repeater 14 using the Zener voltage at both ends of the Zener diode.

The present invention is intended to use part of the power supplied through the feeder line 16 for cooling the electro-optical conversion element, and for this purpose, a device for cooling the element is required. , it must not interfere with the power supply of the power supply line 16. As something that satisfies this, Peltier effect type electricity
A heat conversion element can be mentioned. Even if this Peltier effect electro-thermal conversion element is inserted in series with the voltage generating circuit 17 into the feeder line 16, it not only has a current capacity sufficient to pass the constant current I, but also exhibits an extremely low impedance. It is something. It is well known that one surface of a Peltier effect electro-thermal conversion element becomes a heat absorption surface and the other surface becomes a heat radiation surface when a current is passed therethrough.

FIG. 2 is a diagram showing a configuration when the present invention is applied to the area within circle A in FIG. 1. Note that the same components as in FIG. 1 are designated with the same reference numerals. In this figure, 10 is an electro-optical conversion element to be cooled, which is connected to an optical-electrical conversion element 18 that converts an optical signal into an electric signal, and a processing circuit 19 that performs amplification, equalization, and discrimination/regeneration. There is. Now, the cooling means based on the present invention is a Peltier effect type electric-to-optical conversion element, which is shown in 2 in the figure.
It is indicated by 1. The electrothermal conversion element 21 is electrically connected in series with the voltage generation circuit 17. However, when connecting to the power supply line 16, the polarity is set so that the contact surface with the electro-optical conversion element 10 becomes the heat absorption surface 22 (the other surface is the heat radiation surface 23). In this way, the temperature rise of the electro-optical conversion element 10 is suppressed by contact with the heat absorption surface 22, and is dissipated to the outside through the heat radiation surface 23, thereby being efficiently cooled. What should be noted here is that the insertion of the Peltier effect electro-thermal conversion element 21 does not require any design changes to the existing optical communication system, so it has sufficient practical value, and also has sufficient cooling capacity. It is a certain thing. Therefore, the cooling device not only utilizes the inherent cooling function of the Peltier effect electro-thermal conversion element 21 but also fully utilizes its electrical characteristics.

In FIG. 2, the connection between the Peltier effect electro-thermal conversion element 21 and the electro-optical conversion element 10 is merely depicted in principle, and in reality, in order to enhance the cooling effect, a cross-sectional view is shown in FIG. 3. It is preferable to take a structure like this. According to the structure shown in FIG. 3, only the heat of the electro-optical conversion element 10 can be effectively extracted. That is, the electro-optical conversion element 10, which is placed on the electro-thermal conversion element 21 and its heat absorption surface 22 in good thermal contact but electrically insulated, is housed integrally in the package 31. be done. Electricity
The heat radiation surface 23 of the heat conversion element 21 is connected to the package 31.
is bonded to the bottom with good thermal contact but electrical isolation. Furthermore, package 31
A cover 32 is attached to the top surface of the package 31, and the inside of the package 31 is hermetically sealed from the outside. Therefore, the conversion element 21 absorbs only the heat generated by the conversion element 10. As the above-mentioned member for making a good thermal contact and an electrically insulating contact, for example, there is a thin piece of ceramic. Further, numeral 33 in the figure is a rod protruding from the bottom of the package 31, which functions as a support rod for the package 31 and also functions as a heat radiation rod. Therefore, it is desirable that the package 31 and the rod 33 be integrally formed of metal. One lead 34 of the conversion element 10 is grounded to the package 31, and the other lead 35 leads to the processing circuit 19 in FIG. 2 via a bushing 36. If the light output from the conversion element 10 is to be emitted horizontally, a transparent window (not shown) is provided on the side of the package 31. If the light output is emitted upwards, the cover 32 is formed of a transparent plate. Alternatively, one end of the optical fiber cable 13 may be drawn into the package 31. Leads 37 of conversion element 21 are connected to feeder line 16 (FIG. 2) through bushings 38.

As explained above, according to the present invention, it is possible to cool the electro-optical conversion element with a relatively simple device and with almost no changes to existing equipment, thereby improving the life of the optical repeater. At the same time, the reliability of the optical communication system can be greatly improved.

[Brief explanation of the drawing]

Figure 1 is a block diagram for explaining a general power supply method in an optical communication system, and Figure 2 is a block diagram for explaining a general power supply method in an optical communication system.
FIG. 3 is a cross-sectional view showing an example of the structure of the cooling device of the present invention. In the figure, 10 is an electro-optical conversion element, 11 and 12 are terminal stations, 13 is an optical fiber cable,
14 is an optical repeater, 15 is a power supply device, 16 is a power supply line, 17 is a voltage generation circuit, 21 is a Peltier effect electro-thermal conversion element, 22 and 23 are a heat absorption surface and a heat radiation surface thereof, respectively, and 31 is a package. .

Claims (1)

[Scope of Claim for Utility Model Registration] A plurality of optical repeaters inserted into an optical fiber cable laid between terminal stations and having an electrical-to-optical conversion element at each output stage; and a power supply line that supplies power to each of the repeaters via a voltage generating circuit configured to cool the electro-optical conversion element using a Peltier effect electro-thermal conversion element, the optical communication system comprising: An effect-type electro-thermal conversion element is connected in series to the power supply line and bonded to the electro-optical conversion element, with polarity such that the joint surface with the electro-optical conversion element becomes a heat-absorbing surface. Further, the electro-optical conversion element and the Peltier effect electro-thermal conversion element are housed together in a package, these elements are hermetically sealed, and the Peltier effect electro-thermal conversion element is disposed on its heat dissipation surface. 1. An electro-optical conversion element cooling device for an optical repeater, characterized in that it is joined to the package.