Optical module

Abstract

To provide an optical module that can control the temperature of an opto-semiconductor element with low power consumption.SOLUTION: The optical module includes 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, a heater member connected to the first surface and generating heat by receiving power from the outside, and a heat dissipation 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 temperature control of optical semiconductor elements with low power consumption.

[0006] The present disclosure provides an optical module capable of adjusting the temperature of an optical semiconductor element 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; an optical semiconductor element connected to the first surface; a heater member connected to the first surface and receiving power from an external source to generate heat; 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 an optical semiconductor element can be adjusted 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 an outline of the functional configuration of the optical module according to this 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 illustrating a modified example 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, an optical semiconductor element connected to the first surface, a heater member connected to the first surface and receiving electric power from an external source to generate heat, 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 an optical semiconductor element can be adjusted 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, it is possible to suppress a rise in temperature of the optical semiconductor element and adjust the temperature to a desired value.

[0014] (3) In the above (1) or (2), the first surface has a first temperature higher than the phase transformation temperature when the temperature of the second surface is equal to the phase transformation temperature. Also, when the temperature of the second surface is lower than the phase transformation temperature, the temperature of the first surface may be maintained at the first temperature by adjusting the power of the heater member. This is because the temperature of the optical semiconductor element can be adjusted with low power consumption.

[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 any of (1) to (4) above, the second surface has a second temperature lower than the phase transformation temperature when the temperature of the first surface is equal to the phase transformation temperature. The temperature buffer 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, and 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 to promote heat dissipation when the temperature of the optical semiconductor element is high.

[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 adjusted with low power consumption.

[0020] (9) In any one of (1) to (8) above, a temperature detection element may be further provided that is connected to the first surface and generates a detection signal in response to the temperature of the first surface. This is because the temperature of the optical semiconductor element can be adjusted with low power consumption.

[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 redundant explanation. 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, an optical semiconductor element connected to the first surface, a heater member connected to the first surface and receiving electric power from the outside to generate heat, and a heat dissipation member connected to the second surface. The temperature buffering member of 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, a heat dissipation member 30, and a heater member 40.

[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 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 in the high-temperature phase is different from the thermal conductivity of the phase-changing material in the low-temperature phase. In other words, the thermal resistance of the phase-changing material in the high-temperature phase is different from the thermal resistance of the phase-changing material 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, Ag2S 0.2 Se 0.8、 Ag2S 0.4 Se 0.6、 Ag2S 0.6 Se 0.4 and Ag2S 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. A temperature adjustment target 45 described later is connected to the first surface 20S1. The heat dissipation member 30 is connected to the second surface 20S2. Therefore, heat generated in the temperature adjustment target 45 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 in the temperature adjustment target 45 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, the operating temperature of the optical semiconductor element 10 can be lowered when the thermal conductivity of the phase change material is high. Generally, an upper limit is set for the operating temperature of the optical semiconductor element 10, and it is preferable to lower the operating temperature by efficiently dissipating the generated heat to the outside.

[0037] The heat dissipation member 30 preferably has sufficient heat capacity and heat dissipation capability to reduce an increase in temperature of the temperature adjustment target 45 (particularly the optical semiconductor element 10) when dissipating heat generated in the temperature adjustment target 45 to the outside.

[0038] [Heater member 40] The heater member 40 generates heat when power is applied from the outside. The heater member 40 is, for example, a resistive element. The heater member generates Joule heat when a current flows through it.

[0039] <Temperature characteristics of the optical module according to this embodiment> The temperature characteristics of the optical module according to the present embodiment will be described using an optical module 1, which is an example of the optical module according to the present 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 the present embodiment. In FIG. 2, the optical semiconductor element 10 and the heater member 40 will be collectively described as a temperature control target 45. Although the temperature of the optical semiconductor element 10 and the temperature of the heater member 40 may differ from each other to be exact, in the following description, they are considered to be the same as the temperature of the temperature control target 45. As shown in FIG. 1, the heater member 40 may be disposed so as to be in contact with the temperature buffer member 20 together with the optical semiconductor element 10, or the heater member 40 may be placed on the optical semiconductor element 10 so that the heater member 40 and the temperature buffer member 20 sandwich the optical semiconductor element 10.

[0040] 2, a case will be described in which the temperature of the temperature adjustment target 45 is higher than the temperature of the heat dissipation member 30. When the temperature adjustment target 45 generates heat, the temperature of the temperature adjustment target 45 becomes higher than the temperature of the heat dissipation member 30. In a configuration in which the temperature buffer member 20 is sandwiched between the temperature adjustment target 45 and the heat dissipation member 30, heat generated in the temperature adjustment target 45 is transferred from the temperature adjustment target 45 to the heat dissipation member 30 via the temperature buffer member 20. At this time, the direction in which the heat is transferred is equal to the direction in which the temperature adjustment target 45, the temperature buffer member 20, and the heat dissipation member 30 are arranged (first direction).

[0041] When the optical module 1 is operated, the temperature of the optical semiconductor element 10 increases, for example, by self-heating. The heat dissipation member 30 is assumed to be kept 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-heating of 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). The heater member 40 heats the optical semiconductor element 10 so that the temperature (operating temperature) of the optical semiconductor element 10 is kept constant. For example, when the operating temperature of the optical semiconductor element 10 is 50°C, the heater member 40 heats the optical semiconductor element 10 so that the operating temperature increases by 40°C to 90°C. Also, for example, when the operating temperature of the optical semiconductor element 10 is 70° C., the heater member 40 heats the optical semiconductor element 10 such that the operating temperature rises by 20° C. to 90° C. In this manner, when the temperature of the optical semiconductor element 10 is kept constant by the heat generated by the heater member 40, the temperature of the temperature adjustment target 45 is approximately equal to the operating temperature of the optical semiconductor element 10.

[0042] The temperature of the temperature control target 45 is defined as temperature Tld, and the temperature of the heat dissipation member 30 is defined as temperature Tcase. The temperature Tld of the temperature control target 45 is, for example, the temperature at a surface of the temperature control target 45 that contacts the first surface 20S1. The temperature Tcase of the heat dissipation member 30 is, for example, the temperature at a surface of the heat dissipation member 30 that contacts 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 temperature control target 45.

[0043] In the optical module 1, the temperature (internal temperature) inside the temperature buffering member 20 between the temperature control target 45 and the heat dissipation member 30 is considered to change depending on the distance from the temperature control target 45. That is, the closer the position is to the temperature control target 45, the higher the internal temperature is, and the farther the position is from the temperature control target 45, the lower the internal temperature is. 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.

[0044] 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 temperature control target 45 increases. Also, the thickness Lu of the high temperature layer 20u decreases as the temperature Tld of the temperature control target 45 decreases. Note that when the temperature Tld of the temperature control target 45 is lower than the phase transformation temperature Tpt, the high temperature layer 20u of the temperature buffering member 20 does not exist. In that case, when the temperature Tld of the temperature control target 45 becomes lower than the phase transformation temperature Tpt, the temperature buffering member 20 consists only of the low temperature layer 20d.

[0045] The thickness Ld of the low-temperature layer 20d becomes thicker when the temperature Tld of the temperature control target 45 becomes lower. Also, the thickness Ld of the low-temperature layer 20d becomes thinner when the temperature Tld of the temperature control target 45 becomes higher. When the temperature Tcase of the heat dissipation member 30 is higher than the phase transformation temperature Tpt due to heat from the temperature control target 45, the low-temperature layer 20d of the temperature buffering member 20 does not exist. In that case, when the temperature Tcase of the heat dissipation member 30 becomes higher than the phase transformation temperature Tpt, the temperature buffering member 20 becomes only 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 in opposition 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).

[0046] The relationship between the temperature Tld of the temperature adjustment target 45 and the temperature Tcase of the heat dissipation member 30 when the optical semiconductor element 10 and the heater member 40 are operated will be described. Fig. 3 is a diagram for explaining the temperature of the temperature buffer member 20 provided in the optical module 1, which is an example of the optical module according to this embodiment.

[0047] 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 temperature control target 45. 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.

[0048] When the temperature Tld of the temperature control target 45 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 phase is present, so that the temperature Tld of the temperature control target 45 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 temperature control target 45 becomes 60°C, depending on the relationship between the amount of heat generated by the temperature control target 45 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 of the temperature adjustment target 45 is 1W, the temperature Tld of the temperature adjustment target 45 is calculated to be 60°C when the temperature Tcase of the heat dissipation member 30 is 0°C (even if the thermal resistance is 120°C / W and the amount of heat generated is 0.5W, 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 is calculated by multiplying the inverse 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.

[0049] When the temperature Tld of the temperature adjustment target 45 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.

[0050] When the temperature Tld of the temperature control target 45 is 60° C., the temperature Tld of the temperature control target 45 becomes equal to the phase transformation temperature Tpt of the temperature buffering member 20. Therefore, when the temperature Tld of the temperature control target 45 is lower than 60° C., the entire temperature buffering member 20 becomes the low temperature layer 20d. When the temperature Tld of the temperature control target 45 is higher than 60° C., a part of the temperature buffering member 20 close to the temperature control target 45 becomes the high temperature layer 20u.

[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 temperature control target 45 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 temperature control target 45 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 temperature control target 45 and the temperature Tcase of the heat dissipation member 30 are in a proportional relationship, but the slope is gentler than when the temperature Tld of the temperature control target 45 is lower than 60°C. This is because the difference between the temperature Tld of the temperature control target 45 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, here, it is assumed that the amount of heat generated by the temperature control target 45 is constant and does not depend on the temperature Tld of the temperature control target 45.

[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 temperature control target 45 is 85°C. That is, the temperature difference between the temperature Tld of the temperature control target 45 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 temperature control target 45 is 60°C. The temperature Tld of the temperature control target 45 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 above-mentioned 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] 3, when the temperature Tld of the temperature adjustment target 45 is 60° C., the temperature Tcase of the heat dissipation member 30 is 0° C. The temperature of the heat dissipation member 30 when the temperature Tld of the temperature adjustment target 45 is 60° C. is determined by, for example, the thermal resistance of the temperature buffer member 20.

[0059] When the temperature Tld of the temperature adjustment target 45 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 temperature adjustment target 45 and the temperature Tcase of the heat dissipation member 30 are in a proportional relationship, but the slope is gentler than when the temperature Tld of the temperature adjustment target 45 is lower than 60° C.

[0060] When the temperature Tld of the temperature control target 45 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 temperature control target 45 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 entire phase-transforming 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 temperature control target 45 and the temperature Tcase of the heat dissipation member 30 are in a proportional relationship.

[0061] The relationship between the thermal resistance of the temperature buffering member 20 and the temperature Tcase of the heat dissipation member 30 when the temperature adjustment target 45 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.

[0062] 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 buffer 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 buffer member 20. The phase change temperature Tpt of the phase change material constituting the temperature buffer member 20 is 60°C. The thermal conductivity TCu of the high temperature phase of the temperature buffer member 20 is higher than the thermal conductivity TCd of the low temperature phase. In other words, the thermal resistance value TRu of the temperature buffer member 20 when the entire temperature buffer member 20 is in the high temperature phase is lower than the thermal resistance value TRd of the temperature buffer member 20 when the entire temperature buffer member 20 is in the low temperature phase. The thermal resistance value TRd of the temperature buffer member 20 in the low temperature phase may be more than twice the thermal resistance value TRu of the high temperature phase.

[0063] 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. Furthermore, 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 of the high temperature phase, and becomes a constant value.

[0064] 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.

[0065] <Functional configuration of the optical module according to this embodiment> Regarding the optical module according to this embodiment, the function of adjusting the temperature of the optical semiconductor element will be described. Fig. 5 is a diagram for explaining an outline of the functional configuration of an optical module 1, which is an example of the optical module according to this embodiment.

[0066] The optical module 1 further includes a temperature detection element 50 and a control unit 60. The control unit 60 may be provided outside the optical module 1.

[0067] [Temperature detection element 50] The temperature detection element 50 is an element for measuring the temperature in the vicinity of the optical semiconductor element 10. The temperature detection element 50 is, for example, a thermistor, a resistance temperature detector, or a thermocouple.

[0068] [Control unit 60] The control unit 60 controls the heater member 40 based on the temperature detected by the temperature detection element 50 so that the temperature of the optical semiconductor element 10 falls within a desired range. The control unit 60 calculates the temperature of the optical semiconductor element 10, for example, from a change in the resistance value of the temperature detection element 50. For example, the control unit 60 adjusts the power supplied to the heater member 40 by, for example, PID (Proportional-Integral-Differential) control so that the temperature of the optical semiconductor element 10 falls within the desired range. The control unit 60 causes the heater member 40 to generate heat, for example, by applying a predetermined voltage to the heater member 40 and passing a predetermined current therethrough.

[0069] The control unit 60 may control the heater member 40 so that the temperature Tld of the first surface 20S1 is maintained at the temperature Tld of the first surface 20S1 when the temperature Tcase of the second surface 20S2 is equal to the phase transformation temperature Tpt, for example. In other words, the control unit 60 may control the heater member 40 so that the temperature Tld of the first surface 20S1 is maintained at the temperature Tld of the first surface 20S1 when the temperature Tcase of the second surface 20S2 is equal to the phase transformation temperature Tpt, when the temperature Tcase of the second surface 20S2 becomes lower than the phase transformation temperature Tpt. Thereby, for example, even if the temperature Tcase of the second surface 20S2 changes, the temperature Tld of the first surface 20S1 can be maintained at the temperature Tld=85°C of the first surface 20S1 when the temperature Tcase of the second surface 20S2 is equal to the phase transformation temperature Tpt=60°C.

[0070] <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. Fig. 6 is a diagram for explaining the operation of the optical module 1, which is an example of the optical module according to this embodiment.

[0071] 6 is a diagram showing the relationship between the temperature Tcase of the heat dissipation member 30 when the optical module 1 is operated and the power (unit: mW) supplied to the heater member 40. The power is controlled so that the temperature of the optical semiconductor element 10 becomes 90°C. The optical semiconductor element 10 consumes power during operation to generate heat. For example, when the temperature Tcase is 70°C, if the temperature of the optical semiconductor element 10 becomes 90°C due to self-heating of the optical semiconductor element 10, when the temperature Tcase becomes lower than 70°C, the temperature of the optical semiconductor element 10 drops below 90°C. Therefore, the heater member 40 is made to generate heat to maintain the temperature of the optical semiconductor element 10 at 90°C. As the temperature Tcase becomes lower, the power of the heater member 40 increases in order to increase the amount of heat generated by the heater member 40.

[0072] The horizontal axis of FIG. 6 indicates the temperature Tcase (unit: ° C.) of the heat dissipation member 30. The vertical axis of FIG. 6 indicates the power (unit: mW) supplied to the heater member 40. The line Lex indicates a temperature buffer member 20 made of a silver chalcogen compound (AgS 0.4 Se 0.6) is used. Line Lref shows the result when glass is used instead of the temperature buffering member 20.

[0073] As shown in FIG. 6, when controlling the temperature of the optical semiconductor element 10 in the range of, for example, 70° C. or less, the optical module 1 can reduce power consumption in the heater member 40 compared to the case where glass is used instead of the temperature buffer member 20.

[0074] The optical module 1 according to the present embodiment includes the temperature buffering member 20, and as shown in FIG. 4, the temperature Tcase decreases and the thermal resistance of the temperature buffering member 20 increases. As a result, when the temperature Tcase of the optical module is lower than the phase transformation temperature Tpt, the temperature of the optical semiconductor element 10 can be efficiently increased by the heat generated by the heater member 40. Therefore, when the temperature Tcase of the optical module 1 is lower than the phase transformation temperature Tpt, the optical module 1 according to the present embodiment can reduce the power required for heating by the heater member 40 compared to when the temperature buffering member 20 is not used. Furthermore, when the temperature Tcase of the optical semiconductor element 10 is higher than the phase transformation temperature Tpt, the optical module 1 according to the present embodiment includes the temperature buffering member 20, and therefore the thermal resistance of the temperature buffering member 20 is reduced, and the heat generated by the self-heating of the optical semiconductor element 10 can be dissipated by the heat dissipation member 30. As a result, the operating temperature of the optical semiconductor element 10 can be prevented from rising excessively.

[0075] The optical module 1 according to this embodiment includes the temperature buffer member 20, which makes it possible to reduce the power required to adjust the temperature of the optical semiconductor element 10. In particular, when the temperature of the optical semiconductor element 10 is maintained at a predetermined value by the heat generated by the heater member 40, the lower the temperature of the optical module 1, the more the power can be reduced.

[0076] In recent years, the rapid increase in demand at data centers and the global trend toward reducing environmental impact have led to demand for lower power consumption in optical modules. Reducing the power consumption required for temperature control of optical modules will greatly contribute to reducing the power consumption of optical modules.

[0077] According to the optical module of the present embodiment, the temperature buffer member is provided, so that the power consumption can be reduced when adjusting the temperature of the optical semiconductor element. The optical module of the present embodiment can be highly effective in reducing the power consumption by reducing the power consumption when adjusting the temperature of the optical semiconductor element.

[0078] <Modification> A modified example of the optical module according to the present embodiment will be described below. Fig. 7 is a diagram illustrating an optical module 2 which is an example of the optical module according to the present embodiment.

[0079] The optical module 2 includes an optical semiconductor element 10, a carrier 15, a temperature buffering member 20, a heat dissipation member 33, a heater member 40, a temperature detection element 50, and a lens 70. For the optical semiconductor element 10, the temperature buffering member 20, the heater member 40, and the temperature detection element 50, refer to the above descriptions and detailed descriptions thereof will be omitted here.

[0080] [Career 15] The carrier 15 is a substrate on which the optical semiconductor element 10, the heater member 40, and the temperature detection element 50 are mounted. The carrier 15 is made of, for example, a material having low electrical conductivity and high thermal conductivity. More specifically, the carrier 15 is made of aluminum nitride. The carrier 15 is connected to the temperature buffer member 20. The carrier 15 corresponds to the temperature control target 45 illustrated in FIG. 2.

[0081] [Heat dissipation material 33] The heat dissipation member 33 dissipates heat generated in the optical semiconductor element 10. The heat dissipation member 33 includes a plate 31 and a package 32. The plate 31 is connected to the temperature buffer member 20. The package 32 is connected to the plate 31.

[0082] The plate 31 is made of, for example, aluminum nitride. The package 32 is made of, for example, aluminum nitride. The plate 31 and the package 32 may be integrally formed.

[0083] [Lens 70] The lens 70, for example, converts the light emitted from the optical semiconductor element 10 into parallel light. The lens 70 also focuses external light onto the optical semiconductor element 10. The lens 70 is formed of, for example, glass or resin.

[0084] The lens 70 is placed on the temperature buffer member 20, for example.

[0085] 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]

[0086] 1,2 Optical Module 10 Optical semiconductor elements 15 Career 20 Temperature buffer material 20S1 1st page 20S2 2nd page 20d low temperature layer 20u high temperature layer 30, 33 Heat dissipation member 31 Plate 32 Packages 40 Heater parts 45 Temperature Control Target 50 Temperature detection element 60 Control section 70 Lenses Lex, Lref line 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; a heater member connected to the first surface and configured to generate heat by receiving electric power from an external source; 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 temperature of the first surface is maintained at the first temperature by adjusting the power to the heater element when the temperature of the second surface is below the phase transformation temperature.

2. The optical module according to claim 1.

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 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; the temperature buffer member has 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, and has a second thermal resistance between the first surface and the second surface when the temperature of the second surface is equal to the second temperature, the second thermal resistance being greater than the first thermal resistance.

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. Further comprising a temperature detection element connected to the first surface and generating a detection signal in response to a temperature of the first surface. The optical module according to claim 1 .

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