Optical module

Abstract

To provide a low-power consumption optical module that can hold the temperature of an optical semiconductor element within a predetermined range.SOLUTION: The optical module includes a temperature buffer member having a first surface and a second surface opposite the first surface, a self-heating, light-emitting semiconductor device connected to the first surface, and a heat-dissipating member connected to the second surface. The temperature buffer member is composed of a phase-change material whose thermal conductivity changes at a phase-change temperature.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an optical module. [Background technology]

[0002] Patent Document 1 discloses a semiconductor laser module that includes a semiconductor laser and controls the wavelength of light emitted from the semiconductor laser. Patent Document 1 discloses that in the semiconductor laser module, the wavelength is controlled by a heating element that does not involve Peltier cooling.

[0003] Patent Document 2 discloses a submount having a mounting surface on which three or more semiconductor laser elements are mounted in a first direction. Patent Document 1 discloses that the submount includes a heating element for increasing the temperature of the three or more semiconductor laser elements. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-094200 A [Patent Document 2] JP 2018-160520 A Summary of the Invention [Problem to be solved by the invention]

[0005] In optical modules, there is a demand for maintaining the temperature of optical semiconductor elements within a predetermined range while consuming low power.

[0006] The present disclosure provides an optical module that can maintain the temperature of an optical semiconductor element within a predetermined range with low power consumption. [Means for solving the problem]

[0007] The present disclosure relates to an optical module comprising a temperature buffering member having a first surface and a second surface opposite the first surface, a self-heating optical semiconductor element connected to the first surface, and a heat dissipation member connected to the second surface, wherein the temperature buffering member is made of a phase change material whose thermal conductivity changes across a phase change temperature. Effect of the Invention

[0008] According to the optical module of the present disclosure, the temperature of the optical semiconductor element can be maintained within a predetermined range with low power consumption. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an outline of an optical module according to the present embodiment. [Diagram 2] FIG. 2 is a diagram for explaining a state in which the optical module according to this embodiment is used. [Diagram 3] FIG. 3 is a diagram illustrating the temperature of the temperature buffer member included in the optical module according to this embodiment. [Figure 4] FIG. 4 is a diagram illustrating the thermal resistance of the temperature buffer member included in the optical module according to this embodiment. [Diagram 5] FIG. 5 is a diagram for explaining the operation result of the optical module according to the present embodiment. [Figure 6] FIG. 6 is a diagram for explaining the operation result of the optical module according to the present embodiment. [Figure 7] FIG. 7 is a diagram for explaining the operation result of the optical module according to the present embodiment. [Figure 8] FIG. 8 is a diagram for explaining the operation result of the optical module according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described.

[0011] (1) The optical module of the present disclosure includes a temperature buffering member having a first surface and a second surface opposite to the first surface, a self-heating optical semiconductor element connected to the first surface, and a heat dissipation member connected to the second surface. The temperature buffering member is made of a phase change material whose thermal conductivity changes across a phase change temperature.

[0012] According to the optical module of the present disclosure, the temperature of the optical semiconductor element can be maintained within a predetermined range with low power consumption.

[0013] (2) In the above (1), the thermal conductivity of the heat dissipation member may be greater than that of the temperature buffer member. By increasing the thermal conductivity of the heat dissipation member, the change in temperature of the optical semiconductor element caused by the phase change material can be relatively increased.

[0014] (3) In the above (1) or (2), the first surface may have a first temperature higher than the phase transformation temperature when the temperature of the second surface is equal to the phase transformation temperature. Also, the second surface may have a second temperature lower than the phase transformation temperature when the temperature of the first surface is equal to the phase transformation temperature. Furthermore, the first temperature difference between the first temperature and the phase transformation temperature may be set smaller than the second temperature difference between the phase transformation temperature and the second temperature. This is to promote heat dissipation when the temperature of the optical semiconductor element is high.

[0015] (4) In the above (3), the first temperature may be set to a temperature lower than an upper limit operating temperature of the optical semiconductor element, because this allows the optical semiconductor element to operate stably.

[0016] (5) In the above (3) or (4), the temperature buffering member may have a first thermal resistance between the first surface and the second surface when the temperature of the second surface is equal to the phase transformation temperature. Also, the temperature buffering member may have a second thermal resistance between the first surface and the second surface that is larger than the first thermal resistance when the temperature of the second surface is equal to the second temperature. This is because the optical semiconductor element can operate stably.

[0017] (6) In the above (5), the resistance value of the second thermal resistor may be more than twice the resistance value of the first thermal resistor, because this allows the optical semiconductor element to operate stably.

[0018] (7) In any one of the above (1) to (6), the phase-change material may have a phase-change temperature of 70° C. or more and 100° C. or less. This is to promote heat dissipation when the temperature of the optical semiconductor element is high.

[0019] (8) In any one of the above (1) to (7), the phase change material may include any one of silver sulfide, a silver chalcogenide, and copper gallium telluride, because the temperature of the optical semiconductor element can be maintained within a predetermined range with low power consumption.

[0020] (9) In any of the above (1) to (8), any of thermal grease, solder, and metal paste may be further provided between the second surface of the temperature buffering member and the heat dissipating member, because this can improve the efficiency of heat transfer between the temperature buffering member and the heat dissipating member.

[0021] [Details of the embodiment of the present disclosure] Specific examples of the optical module of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0022] In the description of the specification and drawings of each embodiment, components having substantially the same or corresponding functions may be denoted by the same reference numerals to avoid repetitive explanations. In addition, the scale of each part in the drawings may differ from the actual scale in order to facilitate understanding.

[0023] The following embodiments will be described, and at least some of the embodiments described below may be combined in any desired manner.

[0024] The optical module according to the present embodiment includes a temperature buffering member having a first surface and a second surface opposite to the first surface, a self-heating optical semiconductor element connected to the first surface, and a heat dissipation member connected to the second surface. The temperature buffering member in the optical module according to the present embodiment is made of a phase change material whose thermal conductivity changes across a phase change temperature.

[0025] <Configuration of the optical module according to this embodiment> The optical module according to this embodiment will be described using a specific example. Fig. 1 is a perspective view showing an outline of an optical module 1, which is an example of the optical module according to this embodiment.

[0026] The optical module 1 includes an optical semiconductor element 10, a temperature buffer member 20, and a heat dissipation member 30.

[0027] [Optical semiconductor element 10] The optical semiconductor element 10 is an element including a semiconductor that converts light and electricity. The optical semiconductor element 10 also generates heat by itself. The optical semiconductor element 10 is, for example, a laser diode. A laser diode generates heat when it emits light.

[0028] For example, the oscillation wavelength of a laser diode changes with operating temperature at a rate of 0.1 nm / ° C. Therefore, particularly in wavelength division multiplexing communications, it is necessary to maintain the laser diode within a predetermined temperature range.

[0029] Although an example using a laser diode as the optical semiconductor element 10 will be described, the optical semiconductor element 10 is not limited to a laser diode, and may be, for example, an LED (Light Emitting Diode). The optical semiconductor element 10 may be an electroabsorption modulator integrated laser in which a laser diode that outputs continuous light and an electroabsorption modulator that modulates the continuous light are integrated on a single semiconductor chip. The optical semiconductor element 10 is not limited to a light emitting element, and may be applied to all optical semiconductor elements that require temperature adjustment.

[0030] [Temperature buffer material 20] The temperature buffering member 20 is a member whose thermal resistance changes with temperature. The temperature buffering member 20 is made of, for example, a phase change material whose thermal conductivity changes across a phase change temperature. The phase change material includes, for example, any of silver sulfide, a silver chalcogen compound, and copper gallium telluride. Considering the operating range of the optical module 1, the temperature buffering member 20 may have a phase change temperature of, for example, 70°C or more and 100°C or less. The thermal resistance referred to here is the thermal resistance when heat generated in the optical semiconductor element 10 is transferred to the heat dissipation member 30 via the temperature buffering member 20.

[0031] The phase-changing material constituting the temperature buffer member 20 is a material whose state changes between a high-temperature phase and a low-temperature phase at the phase-changing temperature. For example, the thermal conductivity of the phase-changing material when it is in the high-temperature phase is different from the thermal conductivity of the phase-changing material when it is in the low-temperature phase. In other words, the thermal resistance of the phase-changing material when it is in the high-temperature phase is different from the thermal resistance of the phase-changing material when it is in the low-temperature phase. The phase-changing material constituting the temperature buffer member 20 may have an intermediate layer having intermediate properties between the high-temperature phase and the low-temperature phase near the phase-changing temperature.

[0032] The phase change material may be, for example, a silver chalcogenide containing sulfur and selenium. More specifically, the phase change material may be a silver chalcogenide, Ag 2 S 0.2 Se 0.8、 Ag 2 S 0.4 Se 0.6、 Ag 2 S 0.6 Se 0.4 and Ag 2 S 0.8 Se 0.2 Either of the above may be used.

[0033] The silver chalcogen compound is solid in the operating temperature range of the optical module 1, for example, a temperature range from -20°C to 80°C. In addition, in the high-temperature phase of the silver chalcogen compound, the chalcogen atoms form a cubic lattice. In the high-temperature phase of the silver chalcogen compound, the silver atoms move easily. That is, in the high-temperature phase, the silver chalcogen compound becomes a superionic conductor. Furthermore, the thermal conductivity of the silver chalcogen compound changes significantly as it transforms from the low-temperature phase to the high-temperature phase. In addition, the thermal conductivity of the silver chalcogen compound changes significantly in a narrow temperature range.

[0034] The temperature buffering member 20 has a first surface 20S1 (see FIG. 2) and a second surface 20S2 (see FIG. 2) provided opposite to the first surface 20S1. The optical semiconductor element 10 is connected to the first surface 20S1. The heat dissipation member 30 is connected to the second surface 20S2. Therefore, the heat generated in the optical semiconductor element 10 is conducted inside the temperature buffering member 20 from the first surface 20S1 toward the second surface 20S2, and is transferred to the heat dissipation member 30. When the above-mentioned thermal resistance becomes relatively large, the amount of heat conducted from the first surface 20S1 to the second surface 20S2 decreases, and when the above-mentioned thermal resistance becomes relatively small, the amount of heat conducted from the first surface 20S1 to the second surface 20S2 increases. When the heat dissipation member 30 is connected to the temperature buffering member 20, any one of heat dissipation grease, solder, and metal paste may be further provided between the second surface 20S2 and the heat dissipation member 30. This reduces the thermal resistance between the second surface 20S2 and the heat dissipation member 30. With regard to dissipating heat generated in the optical semiconductor element 10, it is preferable that the thermal resistance between the second surface 20S2 and the heat dissipation member 30 is small.

[0035] [Heat dissipation member 30] The heat dissipation member 30 dissipates heat generated by the optical semiconductor element 10 to the outside. The heat dissipation member 30 is made of, for example, a metal. The heat dissipation member 30 is made of, for example, aluminum nitride. The heat dissipation member 30 may be, for example, a part of a housing that houses the optical semiconductor element 10.

[0036] The thermal conductivity of the heat dissipation member 30 may be greater than that of the temperature buffering member 20. By making the thermal conductivity of the heat dissipation member 30 greater than that of the temperature buffering member 20, it is possible to lower the operating temperature of the optical semiconductor element 10 when the thermal conductivity of the temperature buffering member 20 is high. Generally, an upper limit is set for the operating temperature of the optical semiconductor element 10, and it is preferable to efficiently dissipate the generated heat to the outside to lower the operating temperature.

[0037] Heat dissipation member 30 should have sufficient heat capacity and heat dissipation capability to reduce an increase in the operating temperature of optical semiconductor element 10 when dissipating heat generated in optical semiconductor element 10 to the outside.

[0038] <Temperature characteristics of the optical module according to this embodiment> The temperature characteristics of the optical module according to this embodiment will be described using the optical module 1, which is an example of the optical module according to this embodiment. Fig. 2 is a diagram for explaining the use state of the optical module 1, which is an example of the optical module according to this embodiment.

[0039] 2, a case will be described in which the temperature (operating temperature) of the optical semiconductor element 10 is higher than the temperature of the heat dissipation member 30. When the optical semiconductor element 10 generates heat by itself, the operating temperature becomes higher than the temperature of the heat dissipation member 30. In a configuration in which the temperature buffering member 20 is sandwiched between the optical semiconductor element 10 and the heat dissipation member 30, heat generated in the optical semiconductor element 10 is transferred from the optical semiconductor element 10 to the heat dissipation member 30 via the temperature buffering member 20. At this time, the direction in which the heat is transferred is equal to the direction in which the optical semiconductor element 10, the temperature buffering member 20, and the heat dissipation member 30 are arranged (first direction).

[0040] When the optical module 1 is operated, the optical semiconductor element 10 generates heat by itself, causing the temperature to rise. It is assumed that the heat dissipation member 30 is maintained at a substantially constant temperature. For example, if the thermal resistance between the heat dissipation member 30 and the outside is sufficiently smaller than the thermal resistance of the temperature buffer member 20, and the heat capacity of the heat dissipation member 30 is sufficiently large compared to the amount of self-heat generated by the optical semiconductor element 10, the temperature fluctuation of the heat dissipation member 30 can be ignored. Note that, here, it is assumed that the temperature of the heat dissipation member 30 is substantially equal to the outside temperature (for example, the case temperature of the housing or the environmental temperature around the optical module 1).

[0041] The operating temperature of the optical semiconductor element 10 is defined as temperature Tld, and the temperature of the heat dissipation member 30 is defined as temperature Tcase. The temperature Tld, which is the operating temperature of the optical semiconductor element 10, is, for example, the temperature at the surface of the optical semiconductor element 10 that is in contact with the first surface 20S1. The temperature Tcase of the heat dissipation member 30 is, for example, the temperature at the surface of the heat dissipation member 30 that is in contact with the second surface 20S2. The phase transformation temperature of the phase change material constituting the temperature buffer member 20 is defined as phase transformation temperature Tpt. As a temperature condition, a case is assumed in which the phase transformation temperature Tpt is higher than the temperature Tcase of the heat dissipation member 30 and lower than the temperature Tld of the optical semiconductor element 10.

[0042] In the optical module 1, the temperature (internal temperature) inside the temperature buffering member 20 between the optical semiconductor element 10 and the heat dissipation member 30 is considered to change depending on the distance from the self-heating optical semiconductor element 10. That is, the internal temperature is higher at a position closer to the optical semiconductor element 10 and is lower at a position farther from the optical semiconductor element 10. Therefore, as shown in FIG. 2, the temperature buffering member 20 is separated into a high temperature layer 20u and a low temperature layer 20d. The high temperature layer 20u is a layer of the temperature buffering member 20 that is at a temperature higher than the phase transformation temperature Tpt. In other words, the high temperature layer 20u is a layer in which the phase change material is in the high temperature phase. The low temperature layer 20d is a layer of the temperature buffering member 20 that is at a temperature lower than the phase transformation temperature Tpt. In other words, the low temperature layer 20d is a layer in which the phase change material is in the low temperature phase.

[0043] When the temperature of the heat dissipation member 30 is kept constant, the thickness Lu of the high-temperature layer 20u increases as the temperature Tld of the optical semiconductor element 10 increases. Conversely, the thickness Lu of the high-temperature layer 20u decreases as the temperature Tld of the optical semiconductor element 10 decreases. Note that when the temperature Tld of the optical semiconductor element 10 is lower than the phase transformation temperature Tpt, the high-temperature layer 20u does not exist. In that case, the temperature buffer member 20 consists only of the low-temperature layer 20d.

[0044] When the temperature of the heat dissipation member 30 is kept constant, the thickness Ld of the low-temperature layer 20d becomes thicker as the temperature Tld of the optical semiconductor element 10 decreases. Also, when the temperature Tld of the optical semiconductor element 10 increases, the thickness Ld becomes thinner. When the temperature Tcase of the heat dissipation member 30 is higher than the phase transformation temperature Tpt, the low-temperature layer 20d does not exist. In that case, the temperature buffering member 20 consists only of the high-temperature layer 20u. The thickness Lu of the high-temperature layer and the thickness Ld of the low-temperature layer increase and decrease inversely to each other. That is, when the thickness Lu of the high-temperature layer increases, the thickness Ld of the low-temperature layer decreases, and when the thickness Lu of the high-temperature layer decreases, the thickness Ld of the low-temperature layer increases. The sum of the thickness Ld of the high-temperature layer and the thickness Lu of the low-temperature layer is equal to the thickness of the temperature buffering member 20 (the distance between the first surface 20S1 and the second surface 20S2).

[0045] The relationship between the temperature Tld of the optical semiconductor element 10 when the optical semiconductor element 10 is operated and the temperature Tcase of the heat dissipation member 30 will be described. Fig. 3 is a diagram illustrating the temperature of the temperature buffer member 20 included in the optical module 1, which is an example of the optical module according to this embodiment.

[0046] The horizontal axis in FIG. 3 indicates the temperature Tcase (unit: °C) of the heat dissipation member 30. The vertical axis in FIG. 3 indicates the temperature Tld (unit: °C) of the optical semiconductor element 10. The phase transformation temperature Tpt of the phase transformation material constituting the temperature buffer member 20 is 60°C. The thermal conductivity TCu of the high-temperature phase (part where the internal temperature is higher than the phase transformation temperature Tpt) in the temperature buffer member 20 is higher than the thermal conductivity TCd of the low-temperature phase (part where the internal temperature is higher than the phase transformation temperature Tpt). To be precise, for example, even in the high-temperature phase, the thermal conductivity changes depending on the distance from the optical semiconductor element 10, so the value of the thermal conductivity TCu can change depending on the change in thickness Lu, but here it is treated as a constant value. Similarly, the thermal conductivity TCd is also treated as a constant value. In other words, the thermal resistance value TRu of the high-temperature phase in the temperature buffer member 20 is lower than the thermal resistance value TRd of the low-temperature phase. The thermal resistance values ​​TRu and TRd are also treated as constant values.

[0047] When the temperature Tld of the optical semiconductor element 10 is lower than 60°C, in other words, when the temperature Tcase of the heat dissipation member 30 is lower than 0°C, the temperature buffering member 20 is composed of only the low-temperature layer 20d. Therefore, the thermal resistance of the temperature buffering member 20 is the thermal resistance when the entire phase change material constituting the temperature buffering member 20 is in the low-temperature phase. As shown in FIG. 3, when the temperature Tld is 60°C or lower, the thermal resistance of the temperature buffering member 20 is a constant value when only the low-temperature layer is present, so that the temperature Tld of the optical semiconductor element 10 and the temperature Tcase of the heat dissipation member 30 are in a proportional relationship. Note that when the temperature Tcase of the heat dissipation member 30 is 0°C, the temperature Tld of the optical semiconductor element 10 becomes 60°C depending on the relationship between the amount of heat generated by the optical semiconductor element 10 and the thermal resistance of the temperature buffering member 20. For example, when the thermal resistance of the temperature buffering member 20 is 60° C. / W, and the amount of heat generated per unit time by the optical semiconductor element 10 is 1 W, the temperature Tld of the optical semiconductor element 10 is calculated to be 60° C. when the temperature Tcase of the heat dissipation member 30 is 0° C. (Note that even if the thermal resistance is 120° C. / W and the amount of heat generated is 0.5 W, the temperature is the same.) In FIG. 2, when the area of ​​the first surface 20S1 and the area of ​​the second surface 20S2 are equal and the cross-sectional area of ​​the temperature buffering member 20 between the first surface 20S1 and the second surface 20S2 is also equal to the area, the thermal resistance of the temperature buffering member 20 can be found by multiplying the reciprocal of the thermal conductivity of the temperature buffering member 20 by the length of the temperature buffering member 20 (the distance between the area of ​​the first surface 20S1 and the second surface 20S2) and dividing by the area.

[0048] When the temperature Tld of the optical semiconductor element 10 is higher than 60° C. and lower than 85° C., in other words, when the temperature Tcase of the heat dissipation member 30 is higher than 0° C. and lower than 60° C., the temperature buffer member 20 is composed of a high temperature layer 20u and a low temperature layer 20d.

[0049] When the temperature Tld of the optical semiconductor element 10 is 60° C., the temperature Tld of the optical semiconductor element 10 becomes equal to the phase transformation temperature Tpt of the temperature buffering member 20. Therefore, when the temperature Tld of the optical semiconductor element 10 is lower than 60° C., the entire temperature buffering member 20 becomes the low temperature layer 20d. When the temperature Tld of the optical semiconductor element 10 is higher than 60° C., a part of the temperature buffering member 20 close to the optical semiconductor element 10 becomes the high temperature layer 20u.

[0050] 3, when the temperature Tld of the optical semiconductor element 10 is 60° C., the temperature Tcase of the heat dissipation member 30 is 0° C. Whether the temperature Tld of the optical semiconductor element 10 becomes 60° C. when the temperature Tcase of the heat dissipation member 30 is 0° C. is determined by the amount of heat generated per unit time of the optical semiconductor element and the thermal resistance of the temperature buffer member 20, as described above.

[0051] The thickness of the high-temperature layer 20u in the temperature buffering member 20 becomes thicker when the temperature Tcase of the heat dissipation member 30 becomes higher than 0°C, and as a result, the temperature Tld of the optical semiconductor element 10 becomes higher than the phase transformation temperature Tpt. Therefore, when the temperature Tld becomes higher than the phase transformation temperature Tpt, the thermal conductivity of the temperature buffering member 20 becomes higher. In other words, when the temperature Tld becomes higher than the phase transformation temperature Tpt, the thermal resistance value of the temperature buffering member 20 becomes lower.

[0052] When the temperature Tld of the optical semiconductor element 10 is higher than 60°C and lower than 85°C, the thermal resistance of the temperature buffering member 20 gradually decreases. Therefore, as shown in Fig. 3, the temperature Tld of the optical semiconductor element 10 and the temperature Tcase of the heat dissipation member 30 are proportional to each other, but the slope is gentler than when the temperature Tld of the optical semiconductor element 10 is lower than 60°C. This is because the difference between the temperature Tld of the optical semiconductor element 10 and the temperature Tcase of the heat dissipation member 30 decreases as the temperature Tcase increases due to the smaller thermal resistance value of the temperature buffering member 20. Note that it is assumed here that the amount of heat generated by the optical semiconductor element 10 is constant and does not depend on the temperature Tld of the optical semiconductor element 10.

[0053] When the temperature Tcase of the heat dissipation member 30 is 60° C., the temperature Tcase of the heat dissipation member 30 becomes equal to the phase transformation temperature Tpt of the temperature buffering member 20. Therefore, in this case, the entire temperature buffering member 20 becomes the high temperature layer 20u. When the temperature Tcase of the heat dissipation member 30 is lower than 60° C., a part of the temperature buffering member 20 close to the heat dissipation member 30 becomes the low temperature layer 20d.

[0054] In the example of FIG. 3, when the temperature Tcase of the heat dissipation member 30 is 60° C., the temperature Tld of the optical semiconductor element 10 is 85° C. In other words, the temperature difference between the temperature Tld of the optical semiconductor element 10 and the temperature Tcase of the heat dissipation member 30 is 25° C. This is less than half the temperature difference of 60° C. when the temperature Tcase of the heat dissipation member 30 is 0° C. and the temperature Tld of the optical semiconductor element 10 is 60° C. The temperature Tld of the optical semiconductor element 10 when the temperature Tcase of the heat dissipation member 30 is 60° C. is determined by, for example, the thermal resistance of the temperature buffering member 20. Therefore, the decrease in the temperature difference occurs due to a decrease in the thermal resistance of the temperature buffering member 20.

[0055] 3, when the temperature Tcase of the second surface 20S2 is the phase transformation temperature Tpt, that is, 60° C., the temperature Tld of the first surface 20S1 is 85° C. In other words, when the temperature Tcase of the second surface 20S2 is the phase transformation temperature Tpt, the temperature difference (first temperature difference) between the temperature Tld of the first surface 20S1 and the phase transformation temperature Tpt is 25° C. When the temperature Tcase of the second surface 20S2 is the phase transformation temperature Tpt, the temperature Tld of the first surface 20S1 is set to a temperature lower than the upper limit of the operating temperature (upper operating temperature limit) of the optical semiconductor element 10.

[0056] 3, when the temperature Tld of the first surface 20S1 is the phase transformation temperature Tpt, the temperature Tcase is 0° C. In other words, when the temperature Tld of the first surface 20S1 is the phase transformation temperature Tpt, the temperature difference (second temperature difference) between the temperature Tcase of the second surface 20S2 and the phase transformation temperature Tpt is 60 degrees.

[0057] As described above, in the temperature buffer member 20, the thermal conductivity TCu of the high temperature phase is greater than the thermal conductivity TCd of the low temperature phase, so that the first temperature difference described above is smaller than the second temperature difference.

[0058] When the temperature Tld of the optical semiconductor element 10 is higher than 85°C, in other words, when the temperature Tcase of the heat dissipation member 30 is higher than 60°C, the temperature Tcase of the heat dissipation member 30 is higher than the phase transformation temperature Tpt. Therefore, when the temperature Tld of the optical semiconductor element 10 is higher than 85°C, the temperature buffering member 20 is composed of the high-temperature layer 20u. Therefore, the thermal resistance of the temperature buffering member 20 is the thermal resistance when the phase-change material constituting the temperature buffering member 20 is in the high-temperature phase. As shown in FIG. 3, when the temperature Tld is 85°C or higher, the thermal resistance of the temperature buffering member 20 is a constant value, so that the temperature Tld of the optical semiconductor element 10 and the temperature Tcase of the heat dissipation member 30 are in a proportional relationship. More specifically, when the temperature Tcase of the heat dissipation member 30 changes, the temperature Tld of the optical semiconductor element 10 changes by the same amount as the change in the temperature Tcase of the heat dissipation member 30. For example, when the temperature Tcase of the heat dissipation member 30 increases by 5°C, the temperature Tld of the optical semiconductor element 10 increases by 5°C.

[0059] The relationship between the thermal resistance of the temperature buffering member 20 and the temperature Tcase of the heat dissipation member 30 when the optical semiconductor element 10 is operated will be described. Fig. 4 is a diagram illustrating the thermal resistance of the temperature buffering member 20 included in the optical module 1, which is an example of the optical module according to this embodiment.

[0060] The horizontal axis in FIG. 4 indicates the temperature Tcase (unit: °C) of the heat dissipation member 30. The vertical axis in FIG. 4 indicates the thermal resistance (unit: K / W) of the temperature buffering member 20. This thermal resistance represents the thermal resistance related to the heat conduction from the first surface 20S1 to the second surface 20S2 of the temperature buffering member 20. The phase change temperature Tpt of the phase change material constituting the temperature buffering member 20 is 60°C. The thermal conductivity TCu of the temperature buffering member 20 in the high temperature phase is higher than the thermal conductivity TCd of the temperature buffering member 20 in the low temperature phase. In other words, the thermal resistance value TRu of the temperature buffering member 20 when the entire temperature buffering member 20 is in the high temperature phase is lower than the thermal resistance value TRd of the temperature buffering member 20 when the entire temperature buffering member 20 is in the low temperature phase. The thermal resistance value TRd may be more than twice the thermal resistance value TRu.

[0061] 4, when the temperature Tcase of the heat dissipation member 30 is lower than 0°C, the thermal resistance of the temperature buffering member 20 becomes equal to the thermal resistance value TRd when the entire temperature buffering member 20 is in the low temperature phase, and becomes a constant value. When the temperature Tcase of the heat dissipation member 30 is higher than 0°C and lower than 60°C, the thermal resistance of the temperature buffering member 20 decreases at a constant rate with respect to the temperature Tcase. When the temperature Tcase of the heat dissipation member 30 is higher than 60°C, the thermal resistance of the temperature buffering member 20 becomes equal to the thermal resistance value TRu when the entire temperature buffering member 20 is in the high temperature phase, and becomes a constant value.

[0062] When the thermal resistance is constant at the thermal resistance value TRd or TRu, as described above, the temperature Tld of the optical semiconductor element 10 changes by the same amount of change as the amount of change in the temperature Tcase of the heat dissipation member 30. On the other hand, when the thermal resistance decreases in proportion to the temperature Tcase, the temperature of the optical semiconductor element 10 changes by an amount of change smaller than the amount of change in the temperature Tcase of the heat dissipation member 30. For example, as shown in FIG. 3, when the temperature Tcase of the heat dissipation member 30 increases from 0° C. to 60° C., the increase in the temperature Tld of the optical semiconductor element 10 is 25° C., which is smaller than the increase in the temperature Tcase of 60° C. The values ​​shown above are merely examples, and the temperature and thermal resistance values ​​may be appropriately determined based on the specifications of the optical module 1 and the optical semiconductor element 10.

[0063] <Operational Results of the Optical Module According to the Present Embodiment> The results when the optical module according to this embodiment is operated will be described below. Each of Fig. 5 to Fig. 8 is a diagram for explaining the results of operation of the optical module 1, which is an example of the optical module according to this embodiment.

[0064] 5 and 6 are diagrams each showing the relationship between the temperature Tcase of the heat dissipation member 30 and the temperature Tld of the optical semiconductor element 10 when the optical module 1 is operated. Fig. 6 is an enlarged view of an area A1 in Fig. 5.

[0065] 5 and 6, the horizontal axis indicates the temperature Tcase (unit: ° C.) of the heat dissipation member 30. The vertical axis indicates the temperature Tld (unit: ° C.) of the optical semiconductor element 10. The line Lex indicates a temperature buffer member 20 made of a silver chalcogenide (Ag 2 S 0.4 Se 0.6 ) is used. Line Lref1 shows the result when glass is used instead of the temperature buffering member 20. Line Lref2 shows the result when aluminum nitride is used instead of the temperature buffering member 20.

[0066] 5 and 6, the optical module 1 can suppress a temperature rise in the temperature Tld of the optical semiconductor element 10 relative to a temperature rise in the temperature Tcase of the heat dissipation member 30 in a temperature range of, for example, 50° C. to 70° C. In other words, the change in the temperature Tld of the optical semiconductor element 10 indicated by the line Lex is about half that of the lines Lref1 and Lref2.

[0067] 5 and 6, when glass or aluminum nitride is used instead of the temperature buffer member 20, the temperature Tld of the optical semiconductor element 10 increases in proportion to the temperature Tcase of the heat dissipation member 30. In other words, since the thermal resistance is constant, the temperature Tld of the optical semiconductor element 10 changes by the same amount as the amount of change in the temperature Tcase of the heat dissipation member 30. For example, when the temperature Tcase of the heat dissipation member 30 increases by 10°C, the temperature Tld of the optical semiconductor element 10 increases by 10°C.

[0068] 7 and 8 are diagrams each showing the relationship between the temperature Tcase in the heat dissipation member 30 when the optical module 1 is operated and the peak wavelength of the emitted light from the optical semiconductor element 10. Fig. 8 is an enlarged view of a region A2 in Fig. 7.

[0069] 7 and 8, the horizontal axis indicates the temperature Tcase (unit: ° C.) of the heat dissipation member 30. The vertical axis indicates the peak wavelength (unit: nm) of the emitted light of the optical semiconductor element 10. The line Lex indicates a temperature buffer member 20 made of a silver chalcogen compound (Ag 2 S 0.4 Se 0.6 ) is used. Line Lref1 shows the result when glass is used instead of the temperature buffering member 20. Line Lref2 shows the result when aluminum nitride is used instead of the temperature buffering member 20.

[0070] 7 and 8, the optical module 1 can reduce the variation in the wavelength of the emitted light from the optical semiconductor element 10 with respect to the temperature rise of the temperature Tcase in the heat dissipation member 30 in the temperature range of, for example, 50° C. to 70° C. This is because the temperature change of the temperature Tld of the optical semiconductor element 10 is reduced, as described above.

[0071] On the other hand, as shown in FIGS. 7 and 8, when glass or aluminum nitride is used instead of temperature buffer member 20, the wavelength of the emitted light from optical semiconductor element 10 varies in proportion to temperature Tcase in heat dissipation member 30.

[0072] The optical module according to the present embodiment includes a temperature buffer member, which can reduce the dissipation of heat self-generated in the optical semiconductor element to the heat dissipation member when the operating temperature of the optical semiconductor element is low. Also, the optical module according to the present embodiment includes a temperature buffer member, which can increase the dissipation of heat self-generated in the optical semiconductor element to the heat dissipation member when the operating temperature of the optical semiconductor element is high.

[0073] The optical module according to the present embodiment includes a temperature buffer member, thereby reducing temperature fluctuations in the optical semiconductor element due to temperature changes in the heat dissipation member 30. The optical module according to the present embodiment reduces temperature fluctuations in the optical semiconductor element, thereby suppressing the effects of temperature fluctuations in the optical semiconductor element on the optical characteristics and electrical characteristics of the optical module.

[0074] In recent years, the rapid increase in demand for data centers and the global trend to reduce environmental impact have created a demand for lower power consumption in optical modules. In light of the demand for lower power consumption in optical modules, a significant reduction in power consumption can be expected by eliminating temperature control components, such as Peltier elements, which account for a large proportion of the power consumption in optical modules.

[0075] According to the optical module of this embodiment, by providing a temperature buffering member, it is possible to reduce temperature fluctuations of the optical semiconductor element due to changes in the surrounding environmental temperature. The optical module of this embodiment can maintain the temperature of the optical semiconductor element within a predetermined range without performing temperature control by cooling or heating by reducing temperature fluctuations in the optical semiconductor element. Furthermore, by providing a temperature buffering member to reduce temperature fluctuations in the optical semiconductor element, it is possible to maintain the temperature of the optical semiconductor element within a predetermined range without consuming power required for temperature control. Therefore, the optical module of this embodiment can maintain the operating temperature of the optical semiconductor element within a predetermined range with low power consumption. In other words, the optical module of this embodiment can be significantly effective in reducing power consumption.

[0076] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0077] 1 Optical module 10 Optical semiconductor elements 20 Temperature buffer material 20d low temperature layer 20S1 1st page 20S2 2nd page 20u high temperature layer 30 Heat dissipation material A1, A2 area Lex, Lref1, Lref2 lines Tcase, Tld temperature TCd, TCu Thermal conductivity Tpt Phase transformation temperature TRd, TRu thermal resistance value

Claims

1. a temperature buffer member having a first surface and a second surface opposite the first surface; an optical semiconductor element connected to the first surface and generating heat; A heat dissipation member connected to the second surface; Equipped with The temperature buffer member is made of a phase change material whose thermal conductivity changes at a phase change temperature. Optical module.

2. The thermal conductivity of the heat dissipation member is greater than the thermal conductivity of the temperature buffer member.

2. The optical module according to claim 1.

3. the first surface has a first temperature that is greater than the phase transformation temperature when a temperature of the second surface is equal to the phase transformation temperature; the second surface has a second temperature that is lower than the phase transformation temperature when the temperature of the first surface is equal to the phase transformation temperature; a first temperature difference between the first temperature and the phase transformation temperature is set to be smaller than a second temperature difference between the phase transformation temperature and the second temperature; 3. The optical module according to claim 2.

4. The first temperature is set to a temperature lower than an upper limit operating temperature of the optical semiconductor element.

4. The optical module according to claim 3.

5. The temperature buffer member is a first thermal resistance between the first surface and the second surface when a temperature of the second surface is equal to the phase transformation temperature; a second thermal resistance between the first surface and the second surface that is greater than the first thermal resistance when the temperature of the second surface is equal to the second temperature; 4. The optical module according to claim 3.

6. The resistance value of the second thermal resistor is greater than twice the resistance value of the first thermal resistor.

6. The optical module according to claim 5.

7. The phase change material has a phase change temperature of 70° C. or more and 100° C. or less. The optical module according to claim 1 .

8. The phase change material includes any one of silver sulfide, silver chalcogenide, and copper gallium telluride. The optical module according to claim 1 .

9. Any one of thermal grease, solder, and metal paste is further provided between the second surface of the temperature buffer member and the heat dissipation member. The optical module according to claim 1 .

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