JP2007194502A - Optical communication module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical communication module capable of suppressing change fluctuations between a temperature in a temperature sensor disposed in a housing and an ambient temperature, and of estimating the ambient temperature with higher degree of precision. <P>SOLUTION: The optical communication module 1 comprises an optical functional unit (subassembly) 3 for incorporating a semiconductor optical device 31 such as a laser diode, a temperature sensor 51 disposed outside the optical functional unit 3, a housing 2 for housing the optical functional unit 3 and temperature sensor 51, a bimetallic element 7 disposed between the temperature sensor 51 and one longitudinal end of the housing 2, and a heat dissipation sheet 8 disposed between the bimetallic element 7 and one longitudinal end of the housing 2. The temperature sensor 51 is embedded in an electronic component 5. The electronic component 5 and the optical function unit 3 are mounted on a wiring board 4. If the temperature in the housing 2 rises, then the bending of the bimetallic element 7 from a reference state increases, thus increasing the compression ratio of the heat dissipation sheet 8 and reducing the thermal resistance value between the one longitudinal end of the housing 2 and the temperature sensor 51. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical communication module provided with a semiconductor optical device.

  In an optical communication module such as a semiconductor laser module for optical communication, in order to stably operate a semiconductor optical element (semiconductor laser element or the like), a temperature control device such as a Peltier element is monitored while monitoring the ambient temperature of the semiconductor optical element. May be used to control the temperature of the semiconductor optical device. For example, Patent Document 1 discloses a semiconductor laser module in which a thermoelectric cooling element and a temperature sensor (thermistor) are mounted in order to perform such temperature control.

JP-A-9-232679

  Conventionally, a temperature sensor for monitoring the temperature of a semiconductor optical device is disposed in the vicinity of the semiconductor optical device in a package containing the semiconductor optical device. However, the temperature of the semiconductor optical device itself and the temperature sensor due to the fact that the position of the semiconductor optical device to be measured is far from the position of the temperature sensor, or heat flows in from the wire connected to the semiconductor optical device. There is a difference between This is an obstacle to improving the accuracy of temperature control.

  In order to solve the above-described problems, in an optical communication module including a package containing a semiconductor optical device as one component (subassembly), another temperature is provided outside the subassembly and within the housing of the optical communication module. A method for estimating an accurate temperature of a semiconductor optical device by measuring the ambient temperature by further arranging a sensor and correcting the temperature sensor measurement value inside the package using the ambient temperature is becoming mainstream. is there.

  However, the amount of current flowing through a semiconductor optical device such as a semiconductor laser device may vary greatly depending on the temperature. That is, at a high temperature, the threshold current increases and at the same time the photoelectric conversion efficiency (slope efficiency) decreases. Therefore, it is necessary to supply a larger current to maintain a constant light emission intensity. Conversely, a smaller current is sufficient at low temperatures. Therefore, the power consumption (heat generation amount) of electronic components (laser drive ICs, etc.) electrically connected to the semiconductor optical device also varies depending on the temperature, and the temperature in the optical communication module housing also varies accordingly. It becomes. From this, the difference between the temperature of the temperature sensor arranged in the housing of the optical communication module and the ambient temperature of the optical communication module fluctuates, so that the ambient temperature can be accurately estimated based on the measurement result of the temperature sensor. Difficult to improve the accuracy of temperature control.

  The present invention has been made in view of the above problems, and provides an optical communication module capable of estimating the ambient temperature more accurately by suppressing fluctuations in the difference between the temperature of the temperature sensor disposed in the housing and the ambient temperature. For the purpose.

  In order to solve the above problems, an optical communication module of the present invention includes an optical functional unit having a semiconductor optical element, a temperature sensor disposed outside the optical functional unit, and a housing for housing the optical functional unit and the temperature sensor. A bimetal element disposed in a space between the temperature sensor and the housing, a heat dissipation sheet disposed in at least one of the temperature sensor and the bimetal element, and between the bimetal element and the housing; It is characterized by providing.

  The optical communication module includes an optical function unit as a subassembly including a semiconductor optical device. In addition, the ambient temperature can be measured (or estimated) by a temperature sensor arranged outside the optical function unit. A bimetal element and a heat radiating sheet are disposed between the temperature sensor and the housing, and the temperature of the housing is transmitted to the temperature sensor through the bimetal and the heat radiating sheet. When the temperature inside the housing rises due to an increase in power consumption, etc., the deflection of the bimetal element from the reference state increases, the compression rate of the heat dissipation sheet increases, and the thermal resistance value between the housing and the temperature sensor decreases. Become. In addition, when the temperature inside the housing decreases due to a decrease in power consumption or the like, the bending of the bimetal element is reduced (approaching the reference state), the compression ratio of the heat dissipation sheet is reduced, and the space between the housing and the temperature sensor is reduced. The thermal resistance value increases. As described above, according to the optical communication module, the thermal resistance value between the temperature sensor and the housing is automatically adjusted according to the temperature inside the housing. Difference fluctuation can be suppressed (close to a constant value). Therefore, the ambient temperature of the optical communication module can be estimated with higher accuracy based on the measured value of the temperature sensor.

  In the optical communication module, the optical function unit may further include a second temperature sensor therein. In the optical communication module, a temperature sensor arranged outside the optical function unit can be used to correct the temperature measurement value by the temperature sensor inside the optical function unit. Since the ambient temperature can be accurately estimated by the temperature sensor arranged outside the optical function unit as described above, the measured value in the second temperature sensor in the optical function unit is corrected, and the semiconductor optical element is more accurately Can be estimated.

  Further, the optical communication module may be characterized in that the disposition position of the heat dissipation sheet and the disposition position of the temperature sensor as seen from the thickness direction of the bimetal element are shifted from each other. As a result, the change in the compression ratio of the heat dissipation sheet with respect to the bending of the bimetal element can be increased. it can.

  Note that when the temperature fluctuation inside the housing is moderate, the optical communication module has a heat dissipating sheet disposition position and a temperature sensor disposition position viewed from the thickness direction of the bimetal element. Good. As a result, the change in the compression ratio of the heat-dissipating sheet with respect to the bending of the bimetal element can be reduced, so that the difference between the temperature of the temperature sensor and the ambient temperature can be accurately brought close to a constant value when the temperature fluctuation inside the housing is moderate. it can.

  The optical communication module may further include a heat transfer plate at least one of between the temperature sensor and the bimetal element and between the bimetal element and the housing. The material of the heat transfer plate is preferably a metal such as copper, iron, aluminum, and kovar. By arbitrarily setting the thickness of the heat transfer plate, the thickness of the bimetal element and the heat radiating sheet can be selected regardless of the distance between the temperature sensor and the casing. The amount of change in the thermal resistance value with the body can be set to some extent freely. Therefore, the difference between the temperature of the temperature sensor and the ambient temperature can be brought closer to a constant value with higher accuracy.

  According to the optical communication module of the present invention, variation in the difference between the temperature of the temperature sensor arranged in the housing and the ambient temperature can be suppressed, and the ambient temperature can be estimated more accurately.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an optical communication module according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a side sectional view showing a configuration of an embodiment of an optical communication module according to the present invention. The optical communication module 1 includes a housing 2, an optical function unit 3 housed in the housing 2, a wiring board 4, an electronic component 5, a heat transfer plate 6, a bimetal element 7, and a heat dissipation sheet 8. The casing 2 is a hollow container having a rectangular cross section extending in a predetermined direction, and includes a top plate 21 and a bottom plate 22. One end of the housing 2 serves as a housing 23 for accommodating an optical connector provided at the tip of the optical fiber.

  The optical function unit 3 is disposed as a subassembly in the optical communication module 1 and includes a semiconductor optical element 31 such as a laser diode or a photodiode. The semiconductor optical device 31 is built in, for example, a coaxial package 32. One end of the package 32 is provided with a sleeve 33 that fits with an optical connector provided at the tip of the optical fiber, and the sleeve 33 is exposed from one end side of the housing 2. A lead pin 34 for electrically connecting the semiconductor optical device 31 and the wiring pattern of the wiring substrate 4 protrudes from the other end of the package 32. The optical function unit 3 of this embodiment further includes a temperature sensor 35 for monitoring the temperature of the semiconductor optical device 31. The temperature sensor 35 is disposed in the vicinity of the semiconductor optical element 31.

  The wiring board 4 is a board for mounting (mounting) the optical functional unit 3 and electronic components electrically connected to the optical functional unit 3. The wiring board 4 is disposed along the top plate 21 and the bottom plate 22 of the housing 2. A lead pin 34 of the optical function unit 3 is fixed to one end of the wiring board 4. The other end of the wiring board 4 is exposed to the outside of the housing 2 and constitutes an electrical connector for inserting the optical communication module 1 into a communication slot of an external device.

  The electronic component 5 is mounted on the wiring board 4 and is electrically connected to the optical function unit 3 through a wiring pattern on the wiring board 4. The electronic component 5 is an IC (for example, a laser driver IC) that is electrically connected to the semiconductor optical device 31 and extracts the function of the semiconductor optical device 31, and includes a temperature sensor 51. That is, the temperature sensor 51 is a temperature sensor arranged outside the optical function unit 3.

  The bimetal element 7 is disposed in a space between the electronic component 5 incorporating the temperature sensor 51 and the top plate 21 of the housing 2. The heat transfer plate 6 is disposed between the bimetal element 7 and the electronic component 5. The back surface 7 b of the bimetal element 7 is fixed to the electronic component 5 via the heat transfer plate 6. Examples of the material of the heat transfer plate 6 include metal materials having good thermal conductivity, such as Cu whose surface is plated with Ni.

  The heat radiation sheet 8 is disposed between the bimetal element 7 and the top plate 21 of the housing 2. The surface 7 a of the bimetal element 7 is joined to the top plate 21 via the heat dissipation sheet 8. In the present embodiment, the disposition position of the heat dissipation sheet 8 viewed from the thickness direction of the bimetal element 7 and the disposition position of the electronic component 5 (temperature sensor 51) viewed from the same direction are shifted from each other. , Not overlapping. That is, the joint surface between the heat transfer plate 6 on the electronic component 5 and the back surface 7b of the bimetal element 7 is close to one end side of the bimetal element 7, and the joint surface between the heat radiation sheet 8 and the surface 7a of the bimetal element 7 is bimetal. The other end of the element 7 is approached.

  As the heat-dissipating sheet 8, a sheet that is softer (has flexibility or compressibility) than a metal is preferable. For example, the hardness of the heat dissipation sheet 8 is preferably 50 or more in terms of penetration, and the thermal conductivity is preferably 1 W / mK or more. In addition, as such a thermal radiation sheet | seat 8, (alpha) GEL (trademark) of a gel material is mentioned, for example.

  Here, FIG. 2A is a side view showing the configuration of the bimetal element 7. The bimetal element 7 is formed by sticking two plate-like bodies 71 and 72 made of different materials. In the case of this embodiment, the thermal expansion coefficient of the plate-like body 71 provided on the front surface 7a side of the bimetal element 7 is larger than the thermal expansion coefficient of the plate-like body 72 provided on the back surface 7b side. Therefore, when the temperature of the bimetal element 7 rises, the plate-like body 71 expands more than the plate-like body 72, and therefore, as shown in FIG. 7 bends.

  The effects of the optical communication module 1 having the above configuration will be described. FIG. 3 is a diagram showing a thermal equivalent circuit in the optical communication module 1. In FIG. 3, the temperature Tj is the temperature of the temperature sensor 51 (electronic component 5), the temperature Tc is the temperature of the housing 2 (more precisely, the temperature of the top plate 21), and the temperature Ta is the optical communication module 1. Ambient temperature. Θj-c is a thermal resistance value between the temperature sensor 51 (electronic component 5) and the housing 2 (top plate 21), and θc-a is the housing 2 (top plate 21) and the optical communication module 1. It is a thermal resistance value between the surroundings.

In FIG. 3, the difference (Tj−Tc) between the temperature Tj of the temperature sensor 51 and the temperature Tc of the housing 2 is expressed by the following formula (1). In the following formula, Pw is a power consumption value of the optical communication module 1.
Tj−Tc = θj−c × Pw (1)
Further, the difference (Tc−Ta) between the temperature Tc of the housing 2 and the ambient temperature Ta is expressed by the following formula (2).
Tc−Ta = θc−a × Pw (2)
Therefore, the difference (Tj−Ta) between the temperature Tj of the temperature sensor 51 and the ambient temperature Ta is expressed by the following formula (3).
Tj−Ta = (θj−c + θc−a) × Pw (3)

  If (θj−c + θc−a) × Pw is a constant value, the ambient temperature Ta can be easily converted and estimated from the value of the temperature Tj (that is, the measured value of the temperature sensor 51). However, when the current consumption amount of the semiconductor optical device 31 depends on the temperature, the power consumption Pw of the optical communication module 1 also depends on the temperature. For example, when the semiconductor optical device 31 is a laser diode, when the temperature rises, the threshold current value of the laser diode increases and the photoelectric conversion efficiency (slope efficiency) decreases. Therefore, a larger driving current is required, and the power consumption of the driver IC for driving the laser diode increases. Even when the semiconductor optical device 31 is a light receiving device such as a photodiode, the power consumption of an amplifier or the like increases as the temperature rises. For this reason, conventionally, it has been difficult to accurately estimate the ambient temperature Ta from the temperature Tj of the temperature sensor 51.

  For example, it is possible to correct the measured value of the temperature sensor 51 by measuring the power consumption Pw of the optical communication module 1, but a large-scale analog circuit or CPU is required to perform the correction calculation, and the circuit The scale will expand. Further, when the power supply IC is not provided, it is difficult to measure the power consumption Pw. There is also a method of measuring the potential difference between both ends of the optical communication module 1 by interposing a resistor, but this is not practical because the power supply voltage in the optical communication module 1 is lowered.

  The optical communication module 1 according to the present embodiment includes the bimetal element 7 and the heat dissipation sheet 8 to solve the above problem. That is, when the internal temperature of the housing 2 rises, the bimetal element 7 bends as shown in FIG. At this time, the heat radiation sheet 8 is compressed by the bimetal element 7. Here, the heat resistance value of the heat radiation sheet 8 depends on the compression rate, and the heat resistance value becomes smaller (that is, the heat conductivity becomes larger) as it is more strongly compressed. The thermal resistance value of the heat radiation sheet 8 also depends on the contact area between the housing 2 and the bimetal element 7, and the thermal resistance value decreases as the contact area increases. In the optical communication module 1 of the present embodiment, when the internal temperature of the housing 2 is low, the bending of the bimetal element 7 from the reference state is small, and the compression rate and the contact area of the heat dissipation sheet 8 are small. Further, as the internal temperature of the housing 2 increases, the deflection of the bimetal element 7 from the reference state increases, and the compression rate and the contact area of the heat dissipation sheet 8 increase. Therefore, contrary to the power consumption Pw of the optical communication module 1, the thermal resistance value against the temperature decrease inside the casing 2 is in the direction in which the thermal resistance value θj-c decreases with respect to the temperature increase inside the casing 2. Each acts in the direction in which θj-c increases.

  Thus, according to the optical communication module 1 of the present embodiment, the thermal resistance value θj between the temperature sensor 51 (electronic component 5) and the housing 2 (top plate 21) according to the temperature inside the housing 2. -c is automatically adjusted and acts in a direction to cancel the influence of fluctuations in the power consumption Pw, so that fluctuations in the difference (Tj-Ta) between the temperature Tj of the temperature sensor 51 and the ambient temperature Ta are suppressed (constant value). Can be brought close to). Therefore, the ambient temperature Ta of the optical communication module 1 can be estimated with higher accuracy based on the measured value of the temperature sensor 51. Further, according to the optical communication module 1 of the present embodiment, when the internal temperature of the housing 2 becomes high, the amount of heat transfer through the heat dissipation sheet 8 increases. Therefore, the operating temperature range on the high temperature side of the optical communication module 1 can be expanded.

  In the present embodiment, the heat dissipation sheet 8 is disposed between the bimetal element 7 and the housing 2 (top plate 21). However, the heat dissipation sheet 8 includes the temperature sensor 51 (electronic component 5) and the bimetal. It may be arranged between the element 7 or may be arranged both between the bimetal element 7 and the housing 2 and between the temperature sensor 51 and the bimetal element 7. The effect of this embodiment can be suitably obtained even by such deformation.

  Further, as in the present embodiment, the optical function unit 3 may include a temperature sensor (second temperature sensor) 35 different from the temperature sensor 51. In the optical communication module 1, a temperature sensor 51 disposed outside the optical function unit 3 is used to correct a measurement value by the temperature sensor 35 of the optical function unit 3 (that is, a temperature measurement value of the semiconductor optical element 31). be able to. According to the optical communication module 1 of the present embodiment, since the ambient temperature Ta can be accurately estimated by the temperature sensor 51, the measurement value in the temperature sensor 35 built in the optical function unit 3 can be corrected more accurately.

  Further, as in the present embodiment, it is preferable that the disposition position of the heat dissipation sheet 8 and the disposition position of the electronic component 5 (temperature sensor 51) viewed from the thickness direction of the bimetal element 7 are shifted from each other. . Thereby, since the change in the compression ratio of the heat dissipation sheet 8 with respect to the bending of the bimetal element 7 can be increased, for example, even when the temperature variation inside the housing 2 is severe, the difference between the temperature Tj of the temperature sensor 51 and the ambient temperature Ta (Tj -Ta) can be brought close to a constant value quickly.

  Further, as in the present embodiment, the optical communication module 1 preferably includes a metal heat transfer plate 6 between the temperature sensor 51 (electronic component 5) and the bimetal element 7. By arbitrarily setting the thickness of the heat transfer plate 6, the thickness of the bimetal element 7 and the heat radiating sheet 8 can be selected regardless of the distance between the temperature sensor 51 and the case 2 (top plate 21). The amount of change in the thermal resistance value θj-c between the temperature sensor 51 and the casing 2 (top plate 21) with respect to temperature fluctuations inside the body 2 can be set to some extent freely. Therefore, the difference (Tj−Ta) between the temperature Tj of the temperature sensor 51 and the ambient temperature Ta can be brought closer to a constant value with higher accuracy.

  In the present embodiment, the heat transfer plate 6 is disposed between the temperature sensor 51 and the bimetal element 7, but the heat transfer plate 6 is disposed between the bimetal element 7 and the housing 2 (top plate 21). May be. In this case, when the optical communication module 1 is manufactured, the bimetal element 7 may be attached to the top plate 21 of the housing 2 via the metal heat transfer plate 6, and the assembly of the optical communication module 1 is further facilitated. . Further, the heat transfer plate 6 may be disposed both between the bimetal element 7 and the top plate 21 and between the temperature sensor 51 and the bimetal element 7.

(Modification)
FIG. 4 is a side sectional view showing a configuration of the optical communication module 11 as a modification of the embodiment. The difference in configuration between the optical communication module 11 of this modification and the optical communication module 1 of the above embodiment is the shape of the bimetal element. That is, the optical communication module 11 of this modification includes a bimetal element 9 instead of the bimetal element 7 of the above embodiment.

  The bimetal element 9 is disposed between the electronic component 5 incorporating the temperature sensor 51 and the top plate 21 of the housing 2. A heat transfer plate 6 is disposed between the bimetal element 9 and the electronic component 5, and a back surface 9 b of the bimetal element 9 is fixed to the electronic component 5 via the heat transfer plate 6. Further, a heat dissipation sheet 8 is disposed between the bimetal element 9 and the top plate 21, and the surface 9 a of the bimetal element 9 is joined to the top plate 21 via the heat dissipation sheet 8.

  In this modification, the disposition position of the heat dissipation sheet 8 viewed from the thickness direction of the bimetal element 9 and the disposition position of the electronic component 5 (temperature sensor 51) viewed from the same direction overlap each other. That is, the joint surface between the heat transfer plate 6 on the electronic component 5 and the back surface 9 b of the bimetal element 9 is located behind the joint surface between the heat radiation sheet 8 and the front surface 9 a of the bimetal element 9. The electronic component 5, the heat transfer plate 6, the bimetal element 9, the heat radiating sheet 8, and the top plate 21 are stacked on the wiring substrate 4 in this order.

  According to the configuration of this modification, the change in the compression ratio of the heat dissipation sheet 8 with respect to the bending of the bimetal element 9 can be reduced, so that the temperature Tj of the temperature sensor 51 and the ambient temperature when the temperature fluctuation inside the housing 2 is moderate The difference from Ta (Tj−Ta) can be brought close to a constant value with high accuracy. As in the above embodiment, the heat dissipation sheet 8 may be disposed between the electronic component 5 and the bimetal element 9, or between the bimetal element 9 and the top plate 21, and between the electronic component 5 and the bimetal. You may arrange | position in both between the elements 9. The heat transfer plate 6 may be disposed between the bimetal element 9 and the top plate 21, or between the bimetal element 9 and the top plate 21, and between the electronic component 5 and the bimetal element 9. It may be arranged on both sides.

  The optical communication module according to the present invention is not limited to the above-described embodiments and modifications, and various other modifications are possible. For example, although the optical function unit 3 has the temperature sensor 35 in the above embodiment, the present invention accurately measures the ambient temperature in the optical communication module in a form in which the optical function unit does not have the temperature sensor. This is also effective when (estimation) is desired.

FIG. 1 is a side sectional view showing a configuration of an embodiment of an optical communication module according to the present invention. FIG. 2A is a side view showing the configuration of the bimetal element. FIG. 2B is a side view showing a state in which the bimetal element is bent. FIG. 3 is a diagram illustrating a thermal equivalent circuit in the optical communication module. FIG. 4 is a side cross-sectional view showing a configuration of a modified example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 ... Optical communication module, 2 ... Housing | casing, 3 ... Optical function part, 4 ... Wiring board, 5 ... Electronic component, 6 ... Heat-transfer board, 7, 9 ... Bimetal element, 8 ... Radiation sheet, 31 ... Semiconductor Optical element, 32... Package, 35, 51... Temperature sensor, 71, 72.

Claims (4)

An optical functional unit having a semiconductor optical element;
A temperature sensor disposed outside the optical function unit;
A housing for housing the optical functional unit and the temperature sensor;
A bimetal element disposed in a space between the temperature sensor and the housing;
An optical communication module comprising: a heat dissipating sheet disposed between at least one of the temperature sensor and the bimetal element and between the bimetal element and the housing.   The optical communication module according to claim 1, wherein the optical function unit further includes a second temperature sensor therein.   3. The optical communication module according to claim 1, wherein the disposition position of the heat dissipation sheet and the disposition position of the temperature sensor are shifted from each other as viewed from the thickness direction of the bimetal element. 5. The heat transfer plate according to claim 1, further comprising a heat transfer plate between at least one of the temperature sensor and the bimetal element and between the bimetal element and the housing. The optical communication module described.

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