JP2001177031A - Optical transmitter-receiver having cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce temperature changes and distributions within an optical transmitter-receiver. SOLUTION: This optical transmitter-receiver module has an upper lid 5 and a lower box 6. The lower box 6 is equipped therein with a semiconductor laser as a light source, an optical modulator, an optical fiber amplifier and a photoelectron element mounting board 2, on which photoelectron elements such as electronic circuits controlling these elements are mounted. A pipe 1, in which a thermal fluid 4 for absorbing heat generated from the elements within the module and carrying the heat outside is circulated, is formed inside the upper lid 5 and the lower box 6. The pipe 1 is spread over inside the upper lid 5 and the lower box 6 in a shape with which internal heat can be collected efficiently. The upper lid 5 and the lower box 6 are provided with thermal fluid gateways 7, 8, respectively. The thermal fluid gateways 7, 8 are connected to a temperature maintenance mechanism outside the module by pipes so that the thermal fluid is circulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed and large-capacity optical transmission / reception apparatus having a cooling device.

[0002]

2. Description of the Related Art In an optical communication network, an optical signal is relayed between a transmitting end and a receiving end in order to compensate for attenuation or waveform disturbance that occurs when an optical pulse signal propagates over a distance of several hundred km. An optical transmitting / receiving device is arranged.

Such an optical transmission / reception device includes an element having a simple optical transmission / reception function and, if necessary, an optical amplification device, an optical phase compensator, an optical retiming device, and a high-speed control AS.
It is configured as one optical transmission / reception module accommodating elements such as an IC and a power supply, or as an optical transmission / reception system accommodating a plurality of optical transmission / reception modules in one housing.

[0004] Optical fibers used in optical communication networks are mainly silica glass fibers, and the wavelength that minimizes transmission loss is 1.31 µm or 1.55 µm. At these wavelengths, the transmission loss is about 0.5 dB / km. However, even if the wavelength slightly changes from this value, the transmission loss exceeds 1 dB / km. Therefore, it is necessary to precisely control the oscillation wavelength of a semiconductor laser used as a light source.

In recent years, the speed of optical communication has been increased, and a transmission rate of 2.4 Gbps to 10 Gbps is currently being put to practical use. In addition, 40 Gbps optical transmission is being researched and developed as next-generation high-speed optical communication.

In order to realize such high-speed optical communication,
Some suggestions have been made. One of them is called wavelength division multiplexing communication, which uses light of different wavelengths centered at 1.31 μm or 1.55 μm and having an interval of 1 to 0.1 μm, to several tens to several tens of waves. One hundred optical signals are transmitted by one optical fiber. In this method, the transmission rate per wavelength is set to the current 2.4G.
The speed can be further increased by keeping the bps to 10 Gbps. For example, at a transmission rate of 10 Gbps, 8
When wavelength multiplexing of 0 waves is performed, a transmission capacity of 800 Gbps can be realized as a whole. But in this case, 8
Since a laser light source for each wavelength of the 0 wave, an optical element for multiplexing / demultiplexing signal lights having different wavelengths, a photodiode for receiving light for each wavelength, and the like are required, the amount of heat generated in the apparatus also increases. In such wavelength multiplexing, it is necessary to control the wavelength of each laser more strictly.

The oscillation wavelength of a semiconductor laser is determined by the energy difference between the valence band and the conduction band of the semiconductor material forming the light emitting layer, that is, the forbidden band width. When the temperature rises, the number of electrons thermally excited from the valence band to the conduction band increases and the forbidden band changes, so that a semiconductor laser for wavelength division multiplex communication requires precise temperature control.

[0008] In order to remove the heat generated in the electronic equipment and suppress the temperature rise, it is necessary to provide a cooling device in the electronic equipment.
For example, JP-A-6-5753, JP-A-7-142
Conventionally, as described in JP-A-886-886 and JP-A-8-288681.

The above publication describes a configuration in which a coolant is circulated between a specific heat generating element and a heat radiating member to suppress a rise in temperature of the specific heat generating element.

[0010]

In the above-mentioned conventional configuration,
Certain heating elements within the device, such as semiconductor lasers, can be cooled. However, the optical transmitting and receiving device includes many optoelectronic devices whose temperature is to be controlled, in addition to the semiconductor laser. For example, elements such as an optical multiplexer / demultiplexer and a wavelength filter have temperature characteristics, and it is necessary to perform temperature management because a change in temperature affects the phase of an optical signal. As an optical amplifier, an optical fiber type amplifier doped with Er ions is often used. This type of amplifier is a high-power semiconductor for exciting an optical signal having a wavelength different from the optical signal to be amplified. Includes elements such as lasers, optical couplers, and optical isolators. An optical fiber doped with Er ions also has a temperature characteristic. When the temperature changes, the refractive index changes, which affects the phase, amplitude, and polarization state of an optical signal.

In the optical transmission / reception device, an optical signal received from the outside is once converted into an electric signal by a photodiode. At the time of the conversion, a part of the signal is converted into heat. Differences occur.

As described above, in the optical transmitting / receiving device, it is necessary to minimize the temperature change and temperature distribution inside the device, but this is not possible with the above-mentioned conventional cooling device. In addition, in a large computer or the like, the entire apparatus is installed in a section where the temperature is kept constant to ensure performance, but it is difficult to place an optical transmitting and receiving apparatus in various environments in such a section. The situation.

For these reasons, it is difficult at present to carry out wavelength multiplex communication of 100 or more waves with an optical transceiver.

SUMMARY OF THE INVENTION It is an object of the present invention to minimize a temperature change and a temperature distribution inside the optical transmitting and receiving apparatus placed in various environments.

[0015]

The above object is achieved by the following means. That is, an optical transmitting and receiving module including an optoelectronic element and an optical waveguide having at least a function of amplifying or shaping a received optical signal and transmitting the optical signal, and a cooling device for removing heat generated inside the module are provided. A heat transfer layer having a fluid inlet and a fluid outlet and having a conduit formed therein communicating with the fluid inlet and the fluid outlet, wherein the fluid inlet and the fluid outlet of the heat transfer layer are connected to the fluid outlet of the cooling device. And an optical transmission / reception device connected to the fluid recovery port by a conduit, wherein the cooling device sends out the fluid whose temperature is controlled from the fluid delivery port.

In the above-described optical transceiver having the cooling device of the present invention, since the heat transfer layer through which the cooling fluid flows inside the module is disposed, the inside of the module can be maintained at a uniform temperature. Therefore, the entire optical fiber having temperature characteristics and other optoelectronic elements can be uniformly cooled, and the wavelength and phase of light oscillated from a semiconductor laser or the like can be precisely controlled, so that circuit operation is stable. However, signal errors and noise are reduced, and wavelength multiplex communication of 100 or more waves can be performed.

The photoelectric element and the optical waveguide can be mounted on the surface of the heat transfer layer facing the inside of the module. Thereby, the heat removal efficiency can be further improved.

The outer wall of the module can be constituted by the heat transfer layer. Thereby, the heat removal efficiency can be further increased.

A heat insulating layer for preventing heat from entering from outside can be provided on the surface of the heat transfer layer facing the outside of the module. By doing so, the device can be installed in an environment where the temperature changes drastically.

[0020] The fluid inlet and outlet of the heat transfer layer can be connected by one non-branched communication passage. This facilitates the production of the heat transfer layer.

The fluid inlet and outlet of the heat transfer layer can be branched into a plurality of narrow tubes near the fluid inlet and connected by a communication passage that rejoins near the outlet. By doing so, the contact area between the fluid and the heat transfer layer increases, and the heat removal efficiency increases.

The arrangement density of the thin tubes on the surface of the heat transfer layer can be changed according to the mounting position of each element having a different calorific value in the module. By doing so, the heat removal effect of the heat transfer layer near the element generating a large amount of heat can be enhanced, and the overall heat removal efficiency can be increased.

In the module, two heat transfer layers are arranged to face each other, and an optoelectronic device and an optical waveguide are mounted on one of the heat transfer layers.
The outer wall of the module can be constituted by the other heat transfer layer. By doing so, the mounted element is cooled from its lower and upper parts, and a large heat removal effect can be obtained.

The space inside the module surrounded by the heat transfer layer and the outer wall can be filled with an inert gas or an inert liquid. In this case, the temperature distribution inside the module can be made more uniform.

A plurality of optical transmitting / receiving modules are provided, and a cooling device is provided with a fluid sending port and a collecting port for each module, and the temperature and flow rate of the fluid sent from each sending port are determined by the internal temperature of each module or the optical signal transmitting / receiving operation. Can be controlled according to the situation. By doing so, temperature control can be performed according to the heat generation status of each module.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the optical transmitting / receiving apparatus of the present invention. FIG. 1A is a perspective view showing the optical transmitting and receiving module with a partially open interior.
(B) is an external view thereof. The module comprises a module upper lid 5 and a module lower box 6. Inside the lower module box 6, an optoelectronic element mounting board 2 on which optoelectronic elements such as a semiconductor laser as a light source, an optical modulator, an optical fiber amplifier, and an electronic circuit for controlling these are mounted is mounted. A conduit 1 for circulating a thermal fluid 4 for absorbing heat generated from elements inside the module and transporting the module to the outside is arranged inside the module upper cover 5 and the module lower box 6.

The conduit 1 has a module upper lid 5 and a module lower box 6 in such a shape that the internal heat can be efficiently recovered.
It is stretched inside. Also, the module cover 5
The module lower box 6 is provided with thermal fluid ports 7 and 8, respectively. The thermal fluid ports 7 and 8 are connected to a temperature holding mechanism 8 outside the module by a conduit. A thermal fluid controlled to a desired temperature by the temperature holding mechanism is supplied to the module. The heat fluid whose temperature has risen by absorbing the heat generated inside the module is collected by the temperature holding mechanism, cooled, turned into a heat fluid of a desired temperature again, and circulated.

The temperature inside the module is determined by the upper lid 5 and the lower box 6
Is maintained at a constant temperature throughout by a thermal fluid circulating inside the. For this reason, the various optoelectronic elements mounted inside the module are also kept at a constant temperature, and it is possible to suppress a fluctuation in temperature and an optical operation fluctuation caused by a temperature distribution inside the module.

The module is covered with a heat insulating material,
Transmission and reception of optical signals between elements inside the module and the outside are performed via the optical fiber 3. In addition, since the area for attaching the electric signal input terminal and the power supply terminal (not shown) is also set to the minimum necessary area, the invasion of heat from the external environment can be minimized.

The optical transmitting and receiving apparatus may be constituted by one module mounted with an optical transmitting and receiving element for transmitting an optical signal of a single wavelength of 10 Gbps, and each of the optical transmitting and receiving elements for transmitting an optical signal having a different wavelength. It may be composed of one housing incorporating a plurality of mounted modules. Alternatively, an element for collectively transmitting and receiving 10 wavelength multiplexed signals of 10 wavelengths is mounted on one module, and an element for collectively transmitting and receiving 10 wavelength multiplexed signals of another band is mounted on another module. An optical circuit for multiplexing / demultiplexing all the wavelength multiplexed signals into one optical fiber may be mounted in one module, so that one optical transmission / reception device may be configured as a whole.

Since the temperature holding mechanism can perform temperature management on a module basis, it is possible to control the temperature of the module on which an electronic / electric element for multiplexing / demultiplexing an electric signal is mounted separately from the optical transmitting / receiving module. It can also be used for heat removal.

Next, the shape of the thermal fluid conduit arranged in the module will be described. FIG. 2A shows an arrangement pattern of hot fluid conduits arranged inside the upper cover or lower box of the optical transceiver module of the above embodiment, and FIG.
Shows the cross section. The thermal fluid conduit 10 is formed from a groove formed in the heat transfer layer 9 which becomes the substrate surface of the upper lid or the lower box. In order to effectively recover the heat generated inside the module and make the temperature inside the module uniform, the ratio of the portion occupied by the thermal fluid conduit on the entire substrate surface (the surface of the heat transfer layer) should be 80% or more. Is preferred.

Here, a hot fluid inlet 11 and an outlet 12 are formed at one end of the rectangular substrate, and conduits communicating with the inlet and the outlet are formed so as to be folded on each side of the substrate and extend in parallel. Thus, the entire substrate surface is cooled. By circulating a hot fluid through the conduit, the temperature inside the module can be made uniform.

As shown in the cross-sectional view of FIG. 2B, an outer surface of the heat transfer layer 9 opposite to the surface on which the elements are mounted is provided to cut off heat transfer between the inside and the outside of the module. Is provided with a heat insulating layer 13, thereby facilitating temperature control inside the module.

Next, an example of a procedure for manufacturing the substrate of the optical transceiver module will be described with reference to FIG. First, a metal flat plate (14) having a thickness of 2 mm, which is a material of a substrate, is prepared ((a) of FIG. 3). The material is preferably a material having high thermal conductivity and easy to process, such as copper, aluminum, and brass. Next, a groove (15) having a width and a depth of 1 mm serving as a thermal fluid conduit is formed in the flat plate using a processing tool such as dicing or an electric file according to the above-described pattern. ((B) of FIG. 3). In the figure, six grooves are shown for simplicity, but a required number of grooves are formed according to the size of the substrate and the like. Next, a metal flat plate 16 having the same material and the same area and a thickness of 1 mm is placed on the metal flat plate 14 (FIG. 3C). These flat plates are joined and integrated with an adhesive or solder to form a thermal fluid conduit (17) (FIG. 3 (d)). Further, a heat insulating plate 18 having the same area and a thickness of 1 mm is bonded (FIG. 3E). Glass, plastic,
Styrofoam or the like can be used. A metal frame for facilitating attachment of the module to the system rack may be further formed thereon, but the description thereof is omitted here. Next, an adapter screw hole 19 for attaching an external conduit for circulating the hot fluid between the hot fluid and the temperature holding mechanism is formed in a portion serving as an inlet / outlet of the hot fluid (FIG. 3 (f)). Next, an adapter 20 to which an external conduit can be attached is inserted into the screw hole 19, and adhered by a seal tape or an adhesive so as not to cause leakage (FIG. 3 (g)).

An element is mounted on the metal surface side of the substrate in which the thermal fluid circulates formed in this way, and if necessary, a plurality of substrates are combined to form a module upper cover or a module lower box. A transmission / reception module can be obtained.

FIG. 4A shows an external view of an optical transmitting / receiving apparatus having a housing including a plurality of optical transmitting / receiving modules. In this configuration, the housing 21 houses ten optical transmission / reception modules A to J and one temperature holding mechanism 23. In this figure, the conduits 24a and 24b for connecting the module A at the upper left end of the housing and the temperature holding mechanism are shown, but other modules and the temperature holding mechanism can also be connected by the conduit. In this example, one temperature holding mechanism 23
Manages the temperature of ten modules, and enables each module to transmit and receive optical signals.

FIG. 4B is a view for explaining circulation of the hot fluid between the module A and the temperature holding mechanism 23. In this configuration, the conduit on the upper lid side of the module A and the conduit on the lower box side are connected in series. That is, the thermal fluid delivered from the module A outlet of the temperature holding mechanism reaches the lower box side inlet via the conduit 24a, circulates through the lower box side conduit, and reaches the outlet. The thermal fluid exiting from the outlet on the lower box side is led to the inlet on the upper lid side by another conduit, circulates through the conduit on the upper lid side, and reaches the upper lid side outlet. The thermal fluid that has exited from the upper lid side outlet is
Through the module A of the temperature holding mechanism.

It is also possible to mount an optoelectronic device on the substrate surface on the upper lid side. In this case, the conduit on the upper lid side and the conduit on the lower box side can be connected in parallel. If the heat value of the modules is not so large, the conduits of several modules can be connected in series.

Hereinafter, some arrangement patterns different from the arrangement pattern of the conduits inside the substrate will be described. FIG.
Shows a simple pattern in which a single conduit with a large cross section is formed between the fluid inlet 25 and the fluid outlet 26 of the substrate. In this pattern, the flow of the thermal fluid inside the substrate is slow, and convection tends to occur. This pattern can be used for a module in which a device that generates a large amount of heat is not mounted on a substrate.

FIG. 6 shows a pattern in which one conduit exiting from the fluid inlet 25 branches symmetrically into a number of parallel thin tubes, and joins again near the fluid outlet 26 into one conduit. This pattern has a high heat recovery efficiency because the contact area between the heat transfer layer and the fluid is large, and each thin tube has the same heat recovery efficiency, so that the effect of keeping the temperature inside the module uniform is high.

FIG. 7 shows another arrangement pattern of the conduits. In FIG. 7A, reference numeral 27 denotes a substrate on which the optoelectronic device is mounted, and reference numerals 28 and 29 denote the optoelectronic devices mounted on the substrate. It is assumed that the element 28 generates a large amount of heat and the element 29 generates a small amount of heat. FIG. 7B shows an arrangement pattern of conduits inside the substrate. The heat fluid introduced from the heat fluid inlet branches off in the middle, one flows so as to circulate under the element 28, the other flows so as to circulate under the element 29, and joins near the outlet 31. In this pattern, the amount of heat removed from the element 28 is increased by arranging a conduit below the element 28 that generates a large amount of heat near the inlet and the outlet. As described above, it is desirable to determine the arrangement pattern of the conduits according to the difference in the amount of heat generated by the elements, and to increase the overall heat recovery efficiency.

Next, the temperature holding mechanism of the optical transceiver according to the present invention will be described. FIG. 8 is a diagram illustrating a heat recovery cycle in which a volatile liquid is circulated as a heat fluid between the optical transceiver module and the temperature holding mechanism. Various optoelectronic devices as heat generating sources are mounted on the optical transmitting and receiving module. Among them, a semiconductor laser as a pumping light source included in an optical fiber amplifier generates a large amount of heat. The output of a semiconductor laser used as a signal light source is several mW, whereas the output of a semiconductor laser used as an excitation light source ranges from several hundred mW to several W, and
The semiconductor laser itself and its power supply are extremely large heat sources.

In order to cool a module having such a large heat generating source, it is necessary to use a heat fluid having a large heat recovery characteristic. For example, it is preferable to configure a system that efficiently recovers heat by using a low-boiling liquid such as petroleum ether, alkanes, or alcohols as a heat fluid and vaporizing it in a conduit.

In such a system, the heat generated by the optoelectronic devices in the module is transferred from the heat transfer layer 33 to the hot fluid conduit 34. On the other hand, the hot fluid is delivered from the hot fluid delivery section 35 of the temperature holding mechanism and reaches the hot fluid conduit 34 via the hot fluid delivery path 37. The heat fluid which has recovered heat and vaporized in the conduit passes through a heat fluid recovery path 38 and a heat fluid condensing section 36.
, Where it is cooled, agglomerated, becomes liquid again, and sent to the thermal fluid delivery unit 35. Heat is efficiently recovered by such a circulation cycle.

The temperature holding mechanism is provided with a fluid sending section and an aggregating section for each module to control the temperature and flow rate of the hot fluid sent according to the internal temperature of each module or the operating condition of optical transmission and reception. Is also good. In this case, it is necessary to provide a sensor for measuring the temperature inside the module, a sensor for detecting the presence / absence of transmission / reception of the optical signal, and a control device for controlling the temperature and the flow rate of the thermal fluid based on the outputs of these sensors.

In addition to the above-described circulation cycle utilizing the phase change of the thermal fluid, the thermal fluid is simply used between the module and the external heat radiating portion without using the phase change for cooling the module having a small calorific value. The cycle of circulating can be used together.

Further, since the optical transmitting / receiving module has a sealed structure, the inside thereof can be filled with an inert gas or liquid to make the temperature inside the module more uniform. When the apparatus is installed at a very low temperature, the thermal fluid may be heated by a temperature holding mechanism.

[0049]

According to the present invention, the inside of the optical transceiver module can be maintained at a uniform temperature, and the optical fiber having temperature characteristics and other optoelectronic elements can be uniformly cooled. As a result, the wavelength, phase, and the like of light oscillated from a semiconductor laser or the like can be precisely controlled.
Wavelength multiplex communication over waves can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical transceiver module according to the present invention.

FIG. 2 is an example of an arrangement pattern of thermal fluid conduits in a substrate inside an optical transceiver module.

FIG. 3 is a diagram illustrating a procedure for manufacturing a substrate inside the optical transceiver module.

FIG. 4 is a diagram showing an overall configuration of an optical transmitting / receiving device of the present invention.

FIG. 5 is another example of the arrangement pattern of the thermal fluid conduits in the substrate inside the optical transceiver module.

FIG. 6 is another example of the arrangement pattern of the thermal fluid conduits in the substrate inside the optical transceiver module.

FIG. 7 is an example of an arrangement of optoelectronic devices on a substrate inside an optical transceiver module and an arrangement pattern of thermal fluid conduits in the substrate corresponding to the arrangement.

FIG. 8 is a diagram illustrating a temperature holding mechanism of the optical transceiver of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat fluid conduit 2 Optoelectronic element mounting board 3 Optical fiber 4 Heat fluid 5 Optical transmission / reception module upper lid 6 Optical transmission / reception module lower box 7, 8 Thermal fluid inlet / outlet 9 Heat transfer layer 10 Thermal fluid conduit 11 Thermal fluid inlet 12 Thermal fluid outlet Reference Signs List 13 heat insulating layer 14, 16 metal flat plate 15 conduit groove 17 heat fluid conduit 18 heat insulating plate 19 screw hole 20 adapter 21 optical transceiver housing 22 optical transceiver module 23 temperature holding mechanism 24a, 24b thermal fluid conduit 25 thermal fluid inlet 26 Thermal Fluid Outlet 27 Substrate 28, 29 Opto-Electronic Device 30 Thermal Fluid Inlet 31 Thermal Fluid Outlet 32 Opto-Electronic Device 33 Heat Transfer Layer 34 Thermal Fluid Pipe 35 Thermal Fluid Delivery Portion 36 Thermal Fluid Aggregation Portion 37 Thermal Fluid Delivery Path 38 Collection route

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04B 10/14 10/04 10/06

Claims (10)

[Claims] An optical transceiver having at least a function of amplifying or shaping a received optical signal and transmitting the same, and an optical transceiver module including an optical waveguide; and a cooling device for removing heat generated inside the module. A heat transfer layer having a fluid inlet and a fluid outlet and having therein a conduit communicating with the fluid inlet and the fluid outlet is disposed in the module, and the fluid inlet and the fluid outlet of the heat transfer layer are provided in the cooling device. The optical transmitting and receiving device is connected to the fluid outlet and the fluid recovery port by conduits, respectively, and the cooling device sends out the fluid whose temperature is controlled from the fluid outlet. 2. The optical transceiver according to claim 1, wherein the photoelectric element and the optical waveguide are mounted on a surface of the heat transfer layer facing the inside of the module. 3. The optical transceiver according to claim 1, wherein the heat transfer layer forms an outer wall of the module. 4. The optical transceiver according to claim 1, wherein a heat insulating layer for preventing heat from entering from outside is provided on a surface of the heat transfer layer facing the outside of the module. . 5. The optical transmitting and receiving device according to claim 1, wherein the fluid inlet and the fluid outlet of the heat transfer layer are connected by a single non-branched communication path. 6. The communication passage according to claim 1, wherein the fluid inlet and the fluid outlet of the heat transfer layer are branched into a plurality of narrow tubes near the fluid inlet, and merge again near the fluid outlet. An optical transmission / reception device connected by: 7. The optical transceiver according to claim 6, wherein an arrangement density of the thin tubes on the heat transfer layer is changed in accordance with a mounting position of each element having a different calorific value. 8. The module according to claim 1, wherein two heat transfer layers are disposed opposite to each other in the module, one of the heat transfer layers is provided with an optoelectronic element and an optical waveguide, and the other heat transfer layer is provided with the other heat transfer layer. An optical transmission / reception device comprising a module outer wall. 9. The optical transceiver according to claim 1, wherein a space inside the module surrounded by the heat transfer layer and the outer wall is filled with an inert gas or an inert liquid. 10. The method according to claim 1, wherein
A plurality of optical transmitting and receiving modules are provided, and the cooling device is provided with a fluid sending port and a fluid collecting port for each module. An optical transmission / reception device controlled according to a situation.