WO2024095405A1 - Optical electric power supply converter - Google Patents

Optical electric power supply converter Download PDF

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Publication number
WO2024095405A1
WO2024095405A1 PCT/JP2022/041024 JP2022041024W WO2024095405A1 WO 2024095405 A1 WO2024095405 A1 WO 2024095405A1 JP 2022041024 W JP2022041024 W JP 2022041024W WO 2024095405 A1 WO2024095405 A1 WO 2024095405A1
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WO
WIPO (PCT)
Prior art keywords
heat transfer
receiving element
transfer member
base
light receiving
Prior art date
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PCT/JP2022/041024
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French (fr)
Japanese (ja)
Inventor
卓郎 山中
悦司 大村
Original Assignee
デクセリアルズ株式会社
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Application filed by デクセリアルズ株式会社 filed Critical デクセリアルズ株式会社
Priority to PCT/JP2022/041024 priority Critical patent/WO2024095405A1/en
Publication of WO2024095405A1 publication Critical patent/WO2024095405A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0232—Optical elements or arrangements associated with the device

Definitions

  • the present invention relates to an optical power converter that converts light input through an optical fiber cable into electricity and supplies it.
  • optical power supply converters are used, which receive light sent via optical fiber cables to the vicinity of the electronic devices, generate photocurrent through photoelectric conversion, and supply power to them.
  • An optical power supply converter has a semiconductor light receiving element for photoelectric conversion.
  • the output voltage of this semiconductor light receiving element is usually less than 1V.
  • an optical power supply converter with a high output voltage is used. For example, as shown in Patent Document 1, by dividing the circular photodiode of the semiconductor light receiving element into multiple equal sector-shaped segments by multiple grooves and connecting these in series, it is possible to increase the output voltage while reducing the output current.
  • the photoelectric conversion efficiency of a semiconductor light receiving element is generally a maximum of around 40%, so part of the input light is converted into electricity and output, and the remainder becomes heat, causing the temperature of the semiconductor light receiving element to rise.
  • the higher the temperature of the semiconductor light receiving element the lower the photoelectric conversion efficiency and the lower the output characteristics of the optical power supply converter.
  • the output characteristics at room temperature represented by curve A1 shift to curve A2 at temperatures higher than room temperature.
  • the higher the temperature the more the maximum operating point Pmax (maximum output power) shifts closer to the origin, resulting in a decrease in output power, so there is a need to promote heat dissipation from the optical power supply converter.
  • Patent Document 2 describes a technology in which a semiconductor laser element is sandwiched between a block and a heat sink to promote heat dissipation from the semiconductor laser element, which generates heat when it emits light.
  • One electrode of the semiconductor laser element is connected to the block, and the other electrode is connected to the heat sink.
  • Patent Document 2 light is emitted from the end face of the semiconductor laser element that is not in contact with the block or heat sink. Therefore, even if the block and heat sink do not transmit light, the block and heat sink can be brought into contact with the front and back sides of the semiconductor laser element, which have a large area, without impeding the emission of light. This makes it easier for heat from the semiconductor laser element to be transferred to the block and heat sink, suppressing the decrease in light emission efficiency and durability caused by heat from the semiconductor laser element.
  • a substrate on which the semiconductor light receiving element is mounted is disposed on the front side or the opposite side (back side) of the semiconductor light receiving element of the optical power supply converter where the photodiode is formed, and light is input to the semiconductor light receiving element from the opposite side of the substrate. Therefore, it is difficult to place a member equivalent to a heat sink on the opposite side of the substrate to the semiconductor light receiving element, as this would block the input light.
  • the present invention aims to provide an optical power converter that can suppress the temperature rise of the semiconductor light receiving element.
  • the optical power supply converter of the invention of claim 1 is an optical power supply converter having a semiconductor light receiving element that photoelectrically converts input light input through an optical fiber cable, and a base for fixing the semiconductor light receiving element, characterized in that the semiconductor light receiving element has a photodiode on a first surface side of a semiconductor substrate that is transparent to the input light, and the first surface side is fixed to the base, and a heat transfer member that is transparent to the input light and is in close contact with a second surface side facing the first surface of the semiconductor substrate is fixed to the base, the input light is configured to pass through the heat transfer member and be incident on the semiconductor light receiving element, and a portion of the heat of the semiconductor light receiving element is configured to be transferred to the base via the heat transfer member.
  • the input light input through the optical fiber cable passes through the heat transfer member attached to the semiconductor light receiving element and enters the semiconductor light receiving element, and a portion of the heat of the semiconductor light receiving element is transferred to the base via the heat transfer member. Therefore, the heat of the semiconductor light receiving element is transferred to the base not only from the first surface side on which the photodiode is formed, but also from the second surface side via the heat transfer member, so that the heat dissipation of the semiconductor light receiving element 10 can be promoted to reduce the temperature rise, and the output reduction of the optical power supply converter can be suppressed.
  • the optical power supply converter of the invention of claim 2 is the invention of claim 1, characterized in that the heat transfer member is integrally formed with legs that extend toward the base and are fixed to the base. According to the above configuration, since the legs are integrally formed with the heat transfer member, the interface between the legs and the base is generally the only interface at which heat transfer is difficult, making it easier to transfer heat to the base.
  • the optical power supply converter of the invention of claim 3 is the invention of claim 1, characterized in that a support portion extending toward the heat transfer member and to which the heat transfer member is fixed is integrally formed on the base. According to the above configuration, the support part to which the heat transfer member is fixed is formed integrally with the base, so that the only interface that generally has difficulty in transferring heat is the interface between the heat transfer member and the support part, making it easier to transfer heat to the base.
  • the optical power supply converter of the present invention is the optical power supply converter of the first aspect, characterized in that the heat transfer member is fixed to the base via a spacer member. According to the above configuration, by fixing the heat transfer member to the base via the spacer member, when the spacer member is formed from a material with excellent thermal conductivity, it is possible to easily transfer heat from the heat transfer member to the base, and it also becomes easier to form the heat transfer member and the base.
  • the optical power supply converter of the invention of claim 5 is characterized in that, in the invention of claim 1, the photodiode is formed by connecting in series a plurality of equal segments divided by grooves extending radially from a center through which the optical axis of the input light passes in a direction perpendicular to the optical axis, and the heat transfer member has a conical concave surface formed so that its axis of symmetry coincides with the optical axis in an area where the input light is irradiated on the opposite side to a contact surface that is in close contact with the second surface side of the semiconductor substrate.
  • the photodiode in order to increase the output voltage, is formed by connecting a plurality of segments, each of which is equally divided by a plurality of grooves extending radially from the center, in series.
  • the irradiation area of the input light from the optical fiber cable is circular, and the light intensity distribution is rotationally symmetrical with respect to the optical axis and the light intensity decreases as it moves away from the optical axis. Therefore, in order to make the light evenly incident on the plurality of segments, the input light is input so that the optical axis passes through the center of the photodiode.
  • the heat transfer member Since the heat transfer member has a conical concave surface formed in the area where the input light is irradiated, the circular irradiation area of the input light incident on this concave surface is converted into an annular shape and incident on the photodiode. Therefore, the input light is effectively utilized by making the part of the input light near the optical axis, which has a high light intensity, incident on the photodiode while avoiding the vicinity of the center of the photodiode where the grooves that cannot be photoelectrically converted are concentrated. This also makes it possible to promote heat dissipation from the semiconductor light receiving element.
  • the optical power converter of the present invention can suppress the temperature rise of the semiconductor light receiving element, and can suppress the decrease in output due to the temperature rise.
  • FIG. 1 is an external view of an optical power supply converter according to an embodiment of the present invention.
  • FIG. 2 is a perspective view of the optical power supply converter with the cover removed.
  • 3 is a cross-sectional view of a main part of the optical power supply converter shown in FIG. 2 taken along line III-III.
  • FIG. 11 is an exploded perspective view showing another example of the heat transfer member. 13 is a graph showing the effect of a heat transfer member.
  • FIG. 4 is a cross-sectional view showing an example of a heat transfer member and a base. 7 is a graph showing the effect of the heat transfer member of FIG. 6 .
  • 11 is a cross-sectional view showing another example of the heat transfer member and the base.
  • FIG. 2 is a plan view showing a first surface side of a semiconductor substrate of the semiconductor light receiving element; 10 is a plan view showing a wiring portion of a substrate on which the semiconductor light receiving element of FIG. 9 is mounted.
  • 11 is a cross-sectional view of a main part of the semiconductor light receiving element of FIG. 9 mounted on the substrate of FIG. 10 taken along the line XI-XI.
  • FIG. 4 is an explanatory diagram of a light intensity distribution of input light.
  • FIG. 2 is an explanatory diagram of a heat transfer member having a conical concave surface.
  • 10 is an explanatory diagram of input light entering a semiconductor light receiving element through a conical concave surface of a heat transfer member; 1 is a diagram illustrating a decrease in output characteristics due to a rise in temperature of a photovoltaic power supply converter.
  • the optical power supply converter 1 has a pair of output terminals 2a, 2b for converting light (input light L1) input via, for example, a single-mode optical fiber cable OC into a current and supplying power to the outside.
  • a substrate 4 is fixed to a base 3 (stem) equipped with the pair of output terminals 2a, 2b, on which a semiconductor light receiving element 10 is mounted for generating a current from the input light L1 by photoelectric conversion.
  • a cover 5 is fixed to the base 3 to protect and block light from the semiconductor light receiving element 10.
  • the input light L1 which is input to the semiconductor light receiving element 10 from the opening 5a provided in the cover 5 via the optical fiber cable OC, is often infrared light with a wavelength in the range of, for example, 1 to 1.6 ⁇ m. After being emitted from the output end E of the optical fiber cable OC, this input light L1 is a conical beam whose irradiation range increases as it travels.
  • the semiconductor light receiving element 10 is a back-illuminated type light receiving element, and as shown in Figs. 2 and 3, a photodiode 12 is formed on the first surface 11a (front side) of a semiconductor substrate 11 that is transparent to the input light L1, and this first surface 11a side is fixed to the substrate 4.
  • the substrate 4 has a wiring portion 4a for extracting the photocurrent generated by the semiconductor light receiving element 10, and the wiring portion 4a is connected to the output terminal portions 2a and 2b by, for example, conductive wires 6a and 6b, respectively.
  • the semiconductor light receiving element 10 has the first surface 11a side facing the base 3, and the first surface 11a side is fixed to the base 3 via the substrate 4.
  • the input light L1 is input from the second surface 11b side (back side) facing the first surface 11a of the semiconductor substrate 11.
  • the substrate 4 is preferably a ceramic substrate, which has better thermal conductivity than an epoxy substrate.
  • the output terminals 2a and 2b are fixed to the base 3, which is made of Kovar, a material that is mainly composed of iron and has a low thermal expansion coefficient, via insulating members 3a and 3b.
  • a heat transfer member 7 is also fixed to the base 3, which is in close contact with the second surface 11b of the semiconductor light receiving element 10, so as to cover the semiconductor light receiving element 10 and the substrate 4.
  • the heat transfer member 7 has a main body 7a formed in a rectangular plate shape and two legs 7b extending from both longitudinal ends of the main body 7a toward the base 3.
  • the main body 7a is a plate made of, for example, silicon (Si) that is transparent to the input light L1 and has excellent thermal conductivity.
  • the thermal conductivity of silicon is lower than that of, for example, gold, copper, aluminum, etc., which are used as wiring materials, but is higher than that of, for example, glass, which is transparent to the input light L1.
  • the two legs 7b are formed integrally with the main body 7a, making it easy for heat to be transferred from the main body 7a to the legs 7b.
  • the two legs 7b are fixed to the base 3 by, for example, a thermally conductive paste as an adhesive.
  • the semiconductor light receiving element 10 and the substrate 4 sandwiched between the heat transfer member 7 and the base 3 are accommodated between the two legs 7b.
  • the main body 7a of the heat transfer member 7 has a portion (contact surface) that is brought into close contact with the second surface 11b of the semiconductor substrate 11 of the semiconductor light receiving element 10, which is polished flat, for example.
  • the second surface 11b of the semiconductor substrate 11 of the semiconductor light receiving element 10 that is brought into close contact with the heat transfer member 7 is also polished flat, for example.
  • the input light L1 passes through the heat transfer member 7 and the semiconductor substrate 11 of the semiconductor light receiving element 10 and enters the photodiode 12. A part of this input light L1 is converted into a current by photoelectric conversion and output, and the rest becomes heat, which increases the temperature of the semiconductor light receiving element 10. Most of the heat from the semiconductor light receiving element 10 is transferred to the base 3.
  • the heat transfer path is a path that transfers to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and a path that transfers to the base 3 via the heat transfer member 7 on the second surface 11b side as shown by arrow H2.
  • the only part of the path indicated by arrow H2 where heat transfer is difficult is the interface between the leg 7b of the heat transfer member 7 and the base 3, but the heat transfer is improved by, for example, a thermal conductive paste.
  • the heat transferred to the base 3 is dissipated from the base 3 to the outside (air, etc.), and is also dissipated to the outside from the cover 5 fixed to the base 3. Heat is transferred to the base 3 from the first surface 11a and the second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation and minimizing the temperature rise of the semiconductor light receiving element 10.
  • the heat transfer member 7 may be formed integrally with a rectangular flat body 7a that is in close contact with the semiconductor light receiving element 10 and legs 7c that run along the outer periphery of the body 7a. This increases the contact area between the heat transfer member 7 and the base 3, making it easier to transfer heat from the semiconductor light receiving element 10 to the base 3 via the heat transfer member 7.
  • the inside of the legs 7c houses the substrate 4 on which the semiconductor light receiving element 10 is mounted, including the portion that electrically connects the output terminals 2a, 2b to the substrate 4.
  • the heat transfer member 7 may have multiple legs that are formed integrally with the rectangular flat body 7a so as to run along the outer periphery of the body 7a.
  • the temperature of the base 3 is maintained at a constant temperature.
  • ⁇ is the type having two legs 7b in Figure 2
  • ⁇ is the type having the leg 7c in Figure 4, where the body 7a of the heat transfer member 7 is the same in size, and the thickness of the leg 7b is the same as the thickness of the leg 7c.
  • the thickness of the leg refers to the length from the side of the leg facing the semiconductor light receiving element 10 (inside) to the opposite side (outside) in the direction away from the semiconductor light receiving element 10.
  • the height of the legs 7b and 7c which corresponds to the total thickness of the semiconductor light receiving element 10 and the substrate 4, is, for example, 0.8 mm.
  • the contact area of the leg 7c in FIG. 4 with the base 3 is approximately twice the contact area of the two legs 7b in FIG. 2 with the base 3.
  • the heat transfer member 7 is formed in a rectangular plate shape, and the two support parts 3c on which both ends of the heat transfer member 7 in close contact with the semiconductor light receiving element 10 are placed and fixed may be formed integrally with the base 3 so as to protrude from the base 3 toward the heat transfer member 7.
  • the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and is also transferred to the base 3 via the heat transfer member 7 on the second surface 11b side that is in close contact with the semiconductor light receiving element 10 and the two support parts 3c as shown by arrow H3.
  • the only place where heat transfer is difficult in the path of arrow H3 is the interface between the heat transfer member 7 and the support parts 3c, but the heat transfer is improved by, for example, a thermally conductive paste that fixes the heat transfer member 7 to the support parts 3c.
  • Heat can be transferred to the base 3 from the first surface 11a and second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation and minimizing temperature rise.
  • Figure 7 shows the results of a simulation showing the relationship between the thickness t of the heat transfer member 7 and the temperature rise ⁇ T of the semiconductor light receiving element 10 when 1 W of input light L1 is input to the optical power supply converter 1 having the heat transfer member 7 and base 3 of Figure 6.
  • the size of the support 3c is equal to the leg 7b of Figure 2. In this case as well, it can be seen that up to a thickness t of about 0.8 mm of the main body 7a, the thicker the heat transfer member 7 is, the smaller the temperature rise ⁇ T of the semiconductor light receiving element 10 becomes, and the easier it is for the heat of the semiconductor light receiving element 10 to be transferred to the base 3 via the heat transfer member 7.
  • the support protruding from the base 3 so as to follow the outer periphery of the heat transfer member 7 formed in a rectangular flat plate shape may be formed integrally with the base 3.
  • metal spacer members 8 made of, for example, aluminum or copper, which have better thermal conductivity than the heat transfer member 7, may be disposed on both ends of the heat transfer member 7 formed in a rectangular plate shape, or along the outer periphery of the heat transfer member 7, and the heat transfer member 7 in close contact with the semiconductor light receiving element 10 may be fixed to the base 3 via the spacer members 8.
  • the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and is transferred to the base 3 via the heat transfer member 7 and spacer member 8 on the second surface 11b side as shown by arrow H4.
  • the path of arrow H4 includes the interface between the spacer member 8 and the heat transfer member 7 and the interface between the spacer member 8 and the base 3, but the heat transfer is improved by, for example, a thermally conductive paste, and the heat is transferred from the heat transfer member 7 to the base 3 via the spacer member 8, which has high thermal conductivity. Therefore, heat can be transferred to the base 3 from the first surface 11a and second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation, minimizing temperature rise, and facilitating the formation of the heat transfer member 7 and base 3.
  • the photodiode 12 of the semiconductor light receiving element 10 has a plurality of segments equally divided in the circumferential direction by a plurality of grooves 13 extending radially from the center C of the photodiode 12, as shown in Fig. 9.
  • the photodiode 12 is equally divided into eight segments, but the number of divisions is appropriately set according to the required voltage.
  • Each of the plurality of segments has a pair of electrodes, and the electrode covering most of the surface of each segment is the second electrode 15, and the other electrode is the first electrode 14.
  • a wiring section 4a is formed on the substrate 4 on which the semiconductor light receiving element 10 is mounted.
  • the wiring section 4a is formed to correspond to the second electrode 15 of each segment and has a wiring pattern that extends to connect to the first electrode 14 of the adjacent segment, and has wiring patterns for connecting the conductive wires 6a, 6b at both ends of the series connection.
  • the multiple first and second electrodes 14, 15 of the semiconductor light receiving element 10 are aligned with the corresponding wiring portion 4a of the substrate 4 and connected, for example, by a lead-free solder paste. This fixes the semiconductor light receiving element 10 to the substrate 4 and forms a photodiode 12 in which multiple segments are connected in series.
  • Figure 11 is a cross-sectional view of a main part of this series-connected photodiode 12, and is a cross-sectional view corresponding to the XI-XI line in Figures 9 and 10.
  • the multiple segments constituting the photodiode 12 are formed on the first surface 11a side of the semiconductor substrate 11, with a circular PIN photodiode formed by stacking a first semiconductor layer 16, a light absorbing layer 17, and a second semiconductor layer 18, and divided equally in the circumferential direction by multiple grooves 13.
  • An insulating layer 19 is formed to cover the inside of the grooves 13 and the second semiconductor layer 18, and a second electrode 15 connected to the second semiconductor layer 18 through an opening formed in the insulating layer 19 is formed so as to cover most of the second semiconductor layer 18.
  • the first electrode 14 is connected to the first semiconductor layer 16 through a connection hole that penetrates the second semiconductor layer 18 and the light absorbing layer 17.
  • An insulating layer 19 is also formed on the inner wall of the connection hole.
  • the semiconductor substrate 11 is, for example, a semi-insulating InP substrate, and the first semiconductor layer 16 is, for example, an n-InP layer.
  • the light absorbing layer 17 is, for example, an InGaAs layer
  • the second semiconductor layer 18 is, for example, a p-InP layer
  • the insulating layer 19 is, for example, a SiO2 layer.
  • the first and second electrodes 14, 15 are formed of a metal containing, for example, gold as a main component.
  • the wiring portion 4a of the substrate 4 is formed of a metal containing, for example, gold or copper as a main component.
  • the first and second electrodes 14, 15 and the corresponding wiring portion 4a are connected by solder paste 20.
  • the optical fiber cable OC is fixed so that the optical axis OA of the input light L1 is perpendicular to the photodiode 12 and passes through the center C of the photodiode 12.
  • the photodiode 12 which has multiple segments connected in series and equally spaced circumferentially, generates heat in response to the input light L1, causing the temperature of the semiconductor light receiving element 10 to rise.
  • a heat transfer member 7 is provided in close contact with the semiconductor light receiving element 10.
  • the input light L1 input through the optical fiber cable OC spreads out in a cone shape.
  • the light intensity distribution of this input light L1 decreases the further away from the optical axis OA of the input light L1, and becomes a Gaussian distribution that is rotationally symmetrical about the optical axis OA.
  • the photodiode 12 has multiple grooves 13 that extend radially from its center C in a direction perpendicular to the optical axis OA, and since photoelectric conversion is not possible in these grooves 13, the areas of high light intensity near the optical axis OA cannot be used near the center C where the multiple grooves 13 are concentrated.
  • a conical concave surface 7d is formed in the area of the heat transfer member 7 where the input light L1 is irradiated.
  • This concave surface 7d is formed by conically recessing the surface of the rectangular, flat body portion 7a of the heat transfer member 7 opposite the surface that is brought into close contact with the semiconductor light receiving element 10.
  • the conical concave surface 7d may be formed by a known etching technique, or the conical concave surface 7d may be formed by polishing.
  • the input light L1 spreads away from the optical axis OA by the conical concave surface 7d, and the circular irradiation area becomes annular. Then, the light with the annular irradiation area is incident on the photodiode 12.
  • the heat transfer member 7 having a conical concave surface 7d prevents the input light L1 from entering near the center C of the photodiode 12 where the multiple radial grooves 13 gather, allowing the input light L1 to be used effectively.
  • the heat of the semiconductor light receiving element 10 is transferred to the base 3 not only through the substrate 4 but also through the heat transfer member 7, promoting heat dissipation from the semiconductor light receiving element 10 and suppressing a rise in temperature of the semiconductor light receiving element 10.
  • the conical concave surface 7d can also be formed on the heat transfer member 7 of the type shown in FIG. 4, FIG. 6, or FIG. 8.
  • curve A1 shows the output characteristics of the optical power converter at a certain temperature (e.g. room temperature), and curve A2 shows the output characteristics when the temperature rises.
  • An increase in temperature causes the maximum output power Pmax to shift closer to the origin, i.e. the maximum output power Pmax decreases.
  • the optical power converter 1 equipped with the heat transfer member 7 can reduce the temperature rise by promoting heat dissipation by transferring some of the heat from the semiconductor light receiving element 10 to the base 3 via the heat transfer member 7, thereby reducing this decrease in output.
  • the input light L1 input to the optical power supply converter 1 via the optical fiber cable OC passes through the heat transfer member 7 that is in close contact with the semiconductor light receiving element 10 and enters the semiconductor light receiving element 10, and a part of the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the heat transfer member 7. Therefore, the heat of the semiconductor light receiving element 10 is transferred to the base 3 not only from the first surface 11a side on which the photodiode 12 is formed, but also from the second surface 11b side to the base 3 via the heat transfer member 7. Therefore, it is possible to promote heat dissipation from the semiconductor light receiving element 10, reduce a temperature rise, and suppress a decrease in the output of the optical power supply converter 1.
  • the only interface where heat transfer is generally difficult is the interface between the legs 7b and the base 3, making it easier to transfer heat to the base 3.
  • the support 3c to which the heat transfer member 7 is fixed is formed integrally with the base 3, the only interface where heat transfer is difficult is the interface between the heat transfer member 7 and the support 3c, making it easier to transfer heat to the base 3.
  • the heat transfer member 7 is fixed to the base 3 via a spacer member 8 made of a material with excellent thermal conductivity, it is easier to transfer heat to the base 3 and it becomes easier to form the heat transfer member 7 and the base 3.
  • the photodiode 12 is formed by connecting multiple segments in series, each segment being equally divided by multiple grooves 13 extending radially from its center C.
  • the irradiation area of the input light L1 from the optical fiber cable OC is circular, and its light intensity distribution is rotationally symmetrical with respect to the optical axis OA, with the light intensity decreasing the farther away from the optical axis OA. Therefore, in order to make the input light L1 evenly incident on the multiple segments, the input light L1 is input so that its optical axis OA passes through the center C of the photodiode 12.
  • the part of the input light L1 with high light intensity near the optical axis OA is not photoelectrically converted, resulting in a large amount of waste.
  • a conical concave surface 7d is formed in the area of the heat transfer member 7 where the input light L1 is irradiated, the circular irradiation area of the input light L1 incident on this concave surface 7d is converted into an annular shape and incident on the photodiode 12. Therefore, the part of the input light L1 with high light intensity is made incident on the photodiode 12, avoiding the vicinity of the center C of the photodiode 12 where the grooves 13 are concentrated, and the input light L1 can be used effectively.
  • the substrate 4 may be a silicon substrate having an insulating layer and a wiring portion 4a on the insulating layer.
  • the wiring portion 4a of the substrate 4 may be formed on the insulating layer of the base 3, and the substrate 4 may be omitted and the semiconductor light receiving element 10 may be fixed to the base 3 to promote heat dissipation.
  • a person skilled in the art may implement the above embodiment in various modified forms without departing from the spirit of the present invention, and the present invention also includes such modified forms.

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  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

[Problem] To provide an optical electric power supply converter that makes it possible to suppress any increase in the temperature of a semiconductor light-receiving element. [Solution] An optical electric power supply converter (1) has: a semiconductor light-receiving element (10) that converts, into electricity, an input light (L1) that has been inputted via an optical fiber cable; and a base (3) for securing the semiconductor light-receiving element (10). In the semiconductor light-receiving element (10), a photodiode (12) is provided on a first surface (11a) side of a semiconductor substrate (11) that is transparent with respect to the input light (L1), the first surface (11a) being secured to the base (3). A heat-conducting member (7) that is in close contact with a second surface (11b) side on the opposite side of the semiconductor substrate (11) from the first surface (11a) is secured to the base (3), the heat-conducting member (7) being transparent with respect to the input light (L1). The input light (L1) passes through the heat-conducting member (7) and enters the semiconductor light-receiving element (10), and part of the heat of the semiconductor light-receiving element (10) is transferred to the base (3) via the heat-conducting member (7).

Description

光給電コンバータOptical power converter
　本発明は、光ファイバケーブルを介して入力される光を電力に変換して給電する光給電コンバータに関する。 The present invention relates to an optical power converter that converts light input through an optical fiber cable into electricity and supplies it.
　給電設備がない遠隔地、給電による微弱な電磁界がノイズとなる環境、防爆を必要とする環境、電気的相互影響がある超高電圧設備内等、特殊な環境では電源ケーブルを介して電子機器類を作動させる電力を供給できない場合がある。そのため、電子機器類の傍まで光ファイバケーブルを介して送られる光を受けて、光電変換によって光電流を生成して給電する光給電コンバータが利用されている。 In special environments, such as remote locations with no power supply facilities, environments where weak electromagnetic fields caused by power supply create noise, environments requiring explosion protection, and ultra-high voltage facilities where electrical interactions occur, it may not be possible to supply power to operate electronic devices via a power cable. For this reason, optical power supply converters are used, which receive light sent via optical fiber cables to the vicinity of the electronic devices, generate photocurrent through photoelectric conversion, and supply power to them.
　光給電コンバータは光電変換用の半導体受光素子を有する。この半導体受光素子の出力電圧は、通常１Ｖ未満である。光給電コンバータからの給電を受ける機器が高い入力電圧を必要とする場合には、出力電圧を高くした光給電コンバータが利用される。例えば特許文献１のように、半導体受光素子の円形のフォトダイオードを複数の溝によって扇形の複数のセグメントに等分し、これらを直列に接続することによって、出力電流は小さくなるが出力電圧を高くすることが可能である。 An optical power supply converter has a semiconductor light receiving element for photoelectric conversion. The output voltage of this semiconductor light receiving element is usually less than 1V. When a device receiving power from an optical power supply converter requires a high input voltage, an optical power supply converter with a high output voltage is used. For example, as shown in Patent Document 1, by dividing the circular photodiode of the semiconductor light receiving element into multiple equal sector-shaped segments by multiple grooves and connecting these in series, it is possible to increase the output voltage while reducing the output current.
　半導体受光素子の光電変換効率は一般的には最大４０％程度であるため、入力光の一部が電力に変換されて出力され、残りは熱となって半導体受光素子の温度が上昇する。そして、半導体受光素子が高温になるほど光電変換効率が低下し、光給電コンバータの出力特性が低下する。例えば図１５の出力特性の例に示すように、曲線Ａ１で表される室温での出力特性が、室温よりも高温では曲線Ａ２のようにシフトする。高温になるほど最大動作点Ｐｍａｘ（最大出力電力）が原点に近づく方向にシフトし、出力電力が低下することになるので、光給電コンバータの放熱を促進させることが求められている。 The photoelectric conversion efficiency of a semiconductor light receiving element is generally a maximum of around 40%, so part of the input light is converted into electricity and output, and the remainder becomes heat, causing the temperature of the semiconductor light receiving element to rise. The higher the temperature of the semiconductor light receiving element, the lower the photoelectric conversion efficiency and the lower the output characteristics of the optical power supply converter. For example, as shown in the example of output characteristics in Figure 15, the output characteristics at room temperature represented by curve A1 shift to curve A2 at temperatures higher than room temperature. The higher the temperature, the more the maximum operating point Pmax (maximum output power) shifts closer to the origin, resulting in a decrease in output power, so there is a need to promote heat dissipation from the optical power supply converter.
　例えば特許文献２には、半導体レーザ素子をブロックとヒートシンクで挟持して、発光時に発熱する半導体レーザ素子の放熱を促進させる技術が記載されている。半導体レーザ素子の一方の電極はブロックに接続され、他方の電極はヒートシンクに接続されている。 For example, Patent Document 2 describes a technology in which a semiconductor laser element is sandwiched between a block and a heat sink to promote heat dissipation from the semiconductor laser element, which generates heat when it emits light. One electrode of the semiconductor laser element is connected to the block, and the other electrode is connected to the heat sink.
米国特許出願公開第２０１１／０１０８０８１号明細書US Patent Application Publication No. 2011/0108081 特開平１－２３５９２号公報Japanese Patent Application Laid-Open No. 1-23592
　特許文献２では、ブロック又はヒートシンクに接触していない半導体レーザ素子端面から光が出射される。それ故、ブロック及びヒートシンクが光を透過させなくても、光の出射を妨げずに、半導体レーザ素子の面積が大きい表面側と裏面側にブロックとヒートシンクを接触させることができる。これにより、半導体レーザ素子の熱がブロックとヒートシンクに伝わりやすくなり、半導体レーザ素子の熱による発光効率の低下、耐久性の低下が抑制される。 In Patent Document 2, light is emitted from the end face of the semiconductor laser element that is not in contact with the block or heat sink. Therefore, even if the block and heat sink do not transmit light, the block and heat sink can be brought into contact with the front and back sides of the semiconductor laser element, which have a large area, without impeding the emission of light. This makes it easier for heat from the semiconductor laser element to be transferred to the block and heat sink, suppressing the decrease in light emission efficiency and durability caused by heat from the semiconductor laser element.
　一方、光給電コンバータの半導体受光素子のフォトダイオードが形成された表面側又はその反対側（裏面側）には、半導体受光素子が搭載される基板が配設され、この基板と反対側から光が半導体受光素子に入力される。従って、半導体受光素子に対して基板と反対側にヒートシンクに相当する部材を配設することは、入力光を遮ることになるので困難である。 On the other hand, a substrate on which the semiconductor light receiving element is mounted is disposed on the front side or the opposite side (back side) of the semiconductor light receiving element of the optical power supply converter where the photodiode is formed, and light is input to the semiconductor light receiving element from the opposite side of the substrate. Therefore, it is difficult to place a member equivalent to a heat sink on the opposite side of the substrate to the semiconductor light receiving element, as this would block the input light.
　それ故、半導体受光素子の熱は、空気に僅かに放熱されること以外は、基板を介して外部に伝わるのみであった。基板に熱が伝わり易くなるようにフォトダイオードが形成された表面側を基板に固定する裏面入射型の半導体受光素子を使用しても、温度上昇を十分に抑制することができず、温度上昇による出力電力の低下が課題となっていた。 As a result, the heat from the semiconductor light receiving element was only transferred to the outside via the substrate, with a small amount dissipated into the air. Even when using a back-illuminated semiconductor light receiving element in which the front side on which the photodiode is formed is fixed to the substrate so that heat can be easily transferred to the substrate, the temperature rise could not be sufficiently suppressed, and the decrease in output power due to the temperature rise became an issue.
　そこで、本発明は、半導体受光素子の温度上昇を抑制することができる光給電コンバータを提供することを目的としている。 The present invention aims to provide an optical power converter that can suppress the temperature rise of the semiconductor light receiving element.
　請求項１の発明の光給電コンバータは、光ファイバケーブルを介して入力される入力光を光電変換する半導体受光素子と、前記半導体受光素子を固定するための基台を有する光給電コンバータにおいて、前記半導体受光素子は、前記入力光に対して透明な半導体基板の第１面側にフォトダイオードを備え、且つ前記第１面側が前記基台に固定され、前記入力光に対して透明な伝熱部材であって、前記半導体基板の前記第１面に対向する第２面側に密着させた伝熱部材が前記基台に固定され、前記入力光が前記伝熱部材を透過して前記半導体受光素子に入射するように構成されると共に、前記半導体受光素子の熱の一部が前記伝熱部材を介して前記基台に伝わるように構成されたことを特徴としている。 The optical power supply converter of the invention of claim 1 is an optical power supply converter having a semiconductor light receiving element that photoelectrically converts input light input through an optical fiber cable, and a base for fixing the semiconductor light receiving element, characterized in that the semiconductor light receiving element has a photodiode on a first surface side of a semiconductor substrate that is transparent to the input light, and the first surface side is fixed to the base, and a heat transfer member that is transparent to the input light and is in close contact with a second surface side facing the first surface of the semiconductor substrate is fixed to the base, the input light is configured to pass through the heat transfer member and be incident on the semiconductor light receiving element, and a portion of the heat of the semiconductor light receiving element is configured to be transferred to the base via the heat transfer member.
　上記構成によれば、光ファイバケーブルを介して入力される入力光が、半導体受光素子に密着させた伝熱部材を透過してこの半導体受光素子に入射し、半導体受光素子の熱の一部が伝熱部材を介して基台に伝わる。従って、半導体受光素子の熱が、フォトダイオードが形成された第１面側から基台に伝わるだけでなく、第２面側からも伝熱部材を介して基台に伝わるので、半導体受光素子１０の放熱を促進させて温度上昇を小さくすることができ、光給電コンバータの出力低下を抑制することができる。 With the above configuration, the input light input through the optical fiber cable passes through the heat transfer member attached to the semiconductor light receiving element and enters the semiconductor light receiving element, and a portion of the heat of the semiconductor light receiving element is transferred to the base via the heat transfer member. Therefore, the heat of the semiconductor light receiving element is transferred to the base not only from the first surface side on which the photodiode is formed, but also from the second surface side via the heat transfer member, so that the heat dissipation of the semiconductor light receiving element 10 can be promoted to reduce the temperature rise, and the output reduction of the optical power supply converter can be suppressed.
　請求項２の発明の光給電コンバータは、請求項１の発明において、前記伝熱部材には、前記基台に向かって延びてこの基台に固定される脚部が一体的に形成されたことを特徴としている。
　上記構成によれば、脚部が伝熱部材と一体的に形成されているので、一般的に伝熱し難くなる界面が脚部と基台の界面のみになり、基台に熱を伝え易くすることができる。 The optical power supply converter of the invention of claim 2 is the invention of claim 1, characterized in that the heat transfer member is integrally formed with legs that extend toward the base and are fixed to the base.
According to the above configuration, since the legs are integrally formed with the heat transfer member, the interface between the legs and the base is generally the only interface at which heat transfer is difficult, making it easier to transfer heat to the base.
　請求項３の発明の光給電コンバータは、請求項１の発明において、前記基台には、前記伝熱部材に向かって延びてこの伝熱部材が固定される支持部が一体的に形成されたことを特徴としている。
　上記構成によれば、伝熱部材が固定される支持部が基台と一体的に形成されているので、一般的に伝熱し難くなる界面が伝熱部材と支持部の界面のみになり、基台に熱を伝え易くすることができる。 The optical power supply converter of the invention of claim 3 is the invention of claim 1, characterized in that a support portion extending toward the heat transfer member and to which the heat transfer member is fixed is integrally formed on the base.
According to the above configuration, the support part to which the heat transfer member is fixed is formed integrally with the base, so that the only interface that generally has difficulty in transferring heat is the interface between the heat transfer member and the support part, making it easier to transfer heat to the base.
　請求項４の発明の光給電コンバータは、請求項１の発明において、前記伝熱部材は、スペーサ部材を介して前記基台に固定されたことを特徴としている。
　上記構成によれば、スペーサ部材を介して伝熱部材を基台に固定することにより、スペーサ部材が熱伝導性に優れた材料で形成されている場合に伝熱部材から基台に熱を伝え易くすることができると共に、伝熱部材及び基台の形成が容易になる。 The optical power supply converter of the present invention according to a fourth aspect is the optical power supply converter of the first aspect, characterized in that the heat transfer member is fixed to the base via a spacer member.
According to the above configuration, by fixing the heat transfer member to the base via the spacer member, when the spacer member is formed from a material with excellent thermal conductivity, it is possible to easily transfer heat from the heat transfer member to the base, and it also becomes easier to form the heat transfer member and the base.
　請求項５の発明の光給電コンバータは、請求項１の発明において、前記フォトダイオードは、前記入力光の光軸が通る中心からこの光軸に直交する方向に放射状に延びる溝によって等分された複数のセグメントが直列接続されて形成され、前記伝熱部材は、前記半導体基板の前記第２面側に密着させる接触面と反対側の前記入力光が照射される領域に、前記光軸に対称軸が一致するように形成された円錐状の凹面を備えたことを特徴としている。
　上記構成によれば、出力電圧を高くするために、フォトダイオードは、その中心から放射状に延びる複数の溝によって等分された複数のセグメントが直列接続されて形成されている。光ファイバケーブルからの入力光の照射領域は円形であり、その光強度分布は光軸から離隔するほど光強度が低下すると共に光軸に対して回転対称なので、複数のセグメントに均等に入射させるために光軸がフォトダイオードの中心を通るように入力光が入力される。伝熱部材には入力光が照射される領域に円錐状の凹面が形成されているので、この凹面に入射した入力光の円形の照射領域が円環状に変換されてフォトダイオードに入射する。従って、光電変換できない溝が集中するフォトダイオードの中心近傍を避けて入力光の光軸近傍の光強度が高い部分をフォトダイオードに入射させて、入力光を有効に利用することができると共に、この半導体受光素子の放熱を促進させることができる。 The optical power supply converter of the invention of claim 5 is characterized in that, in the invention of claim 1, the photodiode is formed by connecting in series a plurality of equal segments divided by grooves extending radially from a center through which the optical axis of the input light passes in a direction perpendicular to the optical axis, and the heat transfer member has a conical concave surface formed so that its axis of symmetry coincides with the optical axis in an area where the input light is irradiated on the opposite side to a contact surface that is in close contact with the second surface side of the semiconductor substrate.
According to the above configuration, in order to increase the output voltage, the photodiode is formed by connecting a plurality of segments, each of which is equally divided by a plurality of grooves extending radially from the center, in series. The irradiation area of the input light from the optical fiber cable is circular, and the light intensity distribution is rotationally symmetrical with respect to the optical axis and the light intensity decreases as it moves away from the optical axis. Therefore, in order to make the light evenly incident on the plurality of segments, the input light is input so that the optical axis passes through the center of the photodiode. Since the heat transfer member has a conical concave surface formed in the area where the input light is irradiated, the circular irradiation area of the input light incident on this concave surface is converted into an annular shape and incident on the photodiode. Therefore, the input light is effectively utilized by making the part of the input light near the optical axis, which has a high light intensity, incident on the photodiode while avoiding the vicinity of the center of the photodiode where the grooves that cannot be photoelectrically converted are concentrated. This also makes it possible to promote heat dissipation from the semiconductor light receiving element.
　本発明の光給電コンバータによれば、半導体受光素子の温度上昇を抑制することができ、温度上昇による出力低下を抑制することができる。 The optical power converter of the present invention can suppress the temperature rise of the semiconductor light receiving element, and can suppress the decrease in output due to the temperature rise.
本発明の実施例に係る光給電コンバータの外観図である。1 is an external view of an optical power supply converter according to an embodiment of the present invention. カバーを外した光給電コンバータの斜視図である。FIG. 2 is a perspective view of the optical power supply converter with the cover removed. 図２の光給電コンバータのIII－III線要部断面図である。3 is a cross-sectional view of a main part of the optical power supply converter shown in FIG. 2 taken along line III-III. 伝熱部材の他の例を示す分解斜視図である。FIG. 11 is an exploded perspective view showing another example of the heat transfer member. 伝熱部材の効果を示すグラフである。13 is a graph showing the effect of a heat transfer member. 伝熱部材及び基台の１例を示す断面図である。FIG. 4 is a cross-sectional view showing an example of a heat transfer member and a base. 図６の伝熱部材の効果を示すグラフである。7 is a graph showing the effect of the heat transfer member of FIG. 6 . 伝熱部材及び基台の他の例を示す断面図である。11 is a cross-sectional view showing another example of the heat transfer member and the base. FIG. 半導体受光素子の半導体基板の第１面側を示す平面図である。2 is a plan view showing a first surface side of a semiconductor substrate of the semiconductor light receiving element; 図９の半導体受光素子が搭載される基板の配線部を示す平面図である。10 is a plan view showing a wiring portion of a substrate on which the semiconductor light receiving element of FIG. 9 is mounted. 図１０の基板に搭載された図９の半導体受光素子のXI－XI線要部断面図である。11 is a cross-sectional view of a main part of the semiconductor light receiving element of FIG. 9 mounted on the substrate of FIG. 10 taken along the line XI-XI. 入力光の光強度分布の説明図である。FIG. 4 is an explanatory diagram of a light intensity distribution of input light. 円錐状の凹面を備えた伝熱部材の説明図である。FIG. 2 is an explanatory diagram of a heat transfer member having a conical concave surface. 伝熱部材の円錐状の凹面を介して半導体受光素子に入射する入力光の説明図である。10 is an explanatory diagram of input light entering a semiconductor light receiving element through a conical concave surface of a heat transfer member; 光給電コンバータの温度上昇による出力特性の低下の説明図である。1 is a diagram illustrating a decrease in output characteristics due to a rise in temperature of a photovoltaic power supply converter.
　以下、本発明を実施するための形態について実施例に基づいて説明する。 Below, the form for implementing the present invention will be explained based on the examples.
　図１、図２に示すように、光給電コンバータ１は、例えばシングルモードの光ファイバケーブルＯＣを介して入力される光（入力光Ｌ１）を電流に変換して外部に給電するための１対の出力端子部２ａ，２ｂを有する。この１対の出力端子部２ａ，２ｂが装備された基台３（ステム）には、光電変換によって入力光Ｌ１から電流を生成するための半導体受光素子１０が搭載された基板４が固定されている。また、半導体受光素子１０の保護及び遮光のために、カバー５が基台３に固定されている。 As shown in Figures 1 and 2, the optical power supply converter 1 has a pair of output terminals 2a, 2b for converting light (input light L1) input via, for example, a single-mode optical fiber cable OC into a current and supplying power to the outside. A substrate 4 is fixed to a base 3 (stem) equipped with the pair of output terminals 2a, 2b, on which a semiconductor light receiving element 10 is mounted for generating a current from the input light L1 by photoelectric conversion. In addition, a cover 5 is fixed to the base 3 to protect and block light from the semiconductor light receiving element 10.
　カバー５に設けられた開口部５ａから光ファイバケーブルＯＣを介して半導体受光素子１０に入力される入力光Ｌ１には、波長が例えば１～１．６μｍ程度の範囲内の赤外光が使用される場合が多い。この入力光Ｌ１は、光ファイバケーブルＯＣの出射端Ｅから出射された後は、進行するほど照射範囲が広がる円錐状のビームである。 The input light L1, which is input to the semiconductor light receiving element 10 from the opening 5a provided in the cover 5 via the optical fiber cable OC, is often infrared light with a wavelength in the range of, for example, 1 to 1.6 μm. After being emitted from the output end E of the optical fiber cable OC, this input light L1 is a conical beam whose irradiation range increases as it travels.
　半導体受光素子１０は裏面入射型の受光素子であり、図２、図３に示すように、入力光Ｌ１に対して透明な半導体基板１１の第１面１１ａ側（表面側）にフォトダイオード１２が形成され、この第１面１１ａ側が基板４に固定されている。基板４は、半導体受光素子１０が生成する光電流を取り出すための配線部４ａを有し、配線部４ａが出力端子部２ａ，２ｂに例えば導電性ワイヤ６ａ，６ｂによって夫々接続されている。第１面１１ａ側を基台３に向けて、第１面１１ａ側が基板４を介して基台３に固定された半導体受光素子１０には、半導体基板１１の第１面１１ａに対向する第２面１１ｂ側（裏面側）から入力光Ｌ１が入力される。基板４は、エポキシ基板よりも熱伝導性に優れたセラミックス基板が好ましい。 The semiconductor light receiving element 10 is a back-illuminated type light receiving element, and as shown in Figs. 2 and 3, a photodiode 12 is formed on the first surface 11a (front side) of a semiconductor substrate 11 that is transparent to the input light L1, and this first surface 11a side is fixed to the substrate 4. The substrate 4 has a wiring portion 4a for extracting the photocurrent generated by the semiconductor light receiving element 10, and the wiring portion 4a is connected to the output terminal portions 2a and 2b by, for example, conductive wires 6a and 6b, respectively. The semiconductor light receiving element 10 has the first surface 11a side facing the base 3, and the first surface 11a side is fixed to the base 3 via the substrate 4. The input light L1 is input from the second surface 11b side (back side) facing the first surface 11a of the semiconductor substrate 11. The substrate 4 is preferably a ceramic substrate, which has better thermal conductivity than an epoxy substrate.
　例えば鉄を主成分とする熱膨張率が小さいコバール製の基台３には、絶縁部材３ａ，３ｂを介して出力端子部２ａ，２ｂが固定されている。また、この基台３には、半導体受光素子１０の第２面１１ｂに密着させた伝熱部材７が、半導体受光素子１０及び基板４を覆うように固定されている。 The output terminals 2a and 2b are fixed to the base 3, which is made of Kovar, a material that is mainly composed of iron and has a low thermal expansion coefficient, via insulating members 3a and 3b. A heat transfer member 7 is also fixed to the base 3, which is in close contact with the second surface 11b of the semiconductor light receiving element 10, so as to cover the semiconductor light receiving element 10 and the substrate 4.
　伝熱部材７は、矩形平板状に形成された本体部７ａと、本体部７ａの長手方向両端部から基台３に向かって延びる２つの脚部７ｂを有する。本体部７ａは、入力光Ｌ１に対して透明であり且つ熱伝導性に優れた例えばシリコン（Ｓｉ）製の板である。シリコンの熱伝導性は、例えば配線材料として用いられる例えば金、銅、アルミニウム等よりも低いが、例えば入力光Ｌ１に対して透明なガラス等よりも高い。２つの脚部７ｂは、本体部７ａと一体的に形成され、本体部７ａから脚部７ｂに熱が伝わり易くなっている。この２つの脚部７ｂが、接着剤として例えば熱伝導ペーストによって基台３に固定されている。伝熱部材７と基台３の間に挟まれる半導体受光素子１０と基板４は、２つの脚部７ｂの間に収容される。 The heat transfer member 7 has a main body 7a formed in a rectangular plate shape and two legs 7b extending from both longitudinal ends of the main body 7a toward the base 3. The main body 7a is a plate made of, for example, silicon (Si) that is transparent to the input light L1 and has excellent thermal conductivity. The thermal conductivity of silicon is lower than that of, for example, gold, copper, aluminum, etc., which are used as wiring materials, but is higher than that of, for example, glass, which is transparent to the input light L1. The two legs 7b are formed integrally with the main body 7a, making it easy for heat to be transferred from the main body 7a to the legs 7b. The two legs 7b are fixed to the base 3 by, for example, a thermally conductive paste as an adhesive. The semiconductor light receiving element 10 and the substrate 4 sandwiched between the heat transfer member 7 and the base 3 are accommodated between the two legs 7b.
　伝熱部材７の本体部７ａは、半導体受光素子１０の半導体基板１１の第２面１１ｂに密着させる部分（接触面）が、例えば研磨されて平坦になっている。また、伝熱部材７に密着させる半導体受光素子１０の半導体基板１１の第２面１１ｂも同様に、例えば研磨されて平坦になっている。半導体受光素子１０と伝熱部材７とを密着させる際に、この密着させる部分の微細な隙間を埋めるために、入力光Ｌ１に対して透明な熱伝導グリスが塗布されてもよい。 The main body 7a of the heat transfer member 7 has a portion (contact surface) that is brought into close contact with the second surface 11b of the semiconductor substrate 11 of the semiconductor light receiving element 10, which is polished flat, for example. Similarly, the second surface 11b of the semiconductor substrate 11 of the semiconductor light receiving element 10 that is brought into close contact with the heat transfer member 7 is also polished flat, for example. When the semiconductor light receiving element 10 and the heat transfer member 7 are brought into close contact with each other, a thermally conductive grease that is transparent to the input light L1 may be applied to fill in any minute gaps in the contacting portion.
　入力光Ｌ１は、伝熱部材７と半導体受光素子１０の半導体基板１１を透過してフォトダイオード１２に入射する。この入力光Ｌ１の一部が光電変換により電流となって出力され、残りは熱となって半導体受光素子１０の温度が上昇する。この半導体受光素子１０の熱の大部分は基台３に伝わる。その伝熱経路は、矢印Ｈ１で示すように第１面１１ａ側の基板４を介して基台３に伝わる経路と、矢印Ｈ２で示すように第２面１１ｂ側の伝熱部材７を介して基台３に伝わる経路である。矢印Ｈ２の経路で伝熱し難いのは、伝熱部材７の脚部７ｂと基台３の界面のみであるが、例えば熱伝導ペーストによって伝熱性を向上させている。基台３に伝わった熱は、基台３から外部（空気等）に放熱され、基台３に固定されたカバー５からも外部に放熱される。半導体受光素子１０の面積が大きい第１面１１ａ側と第２面１１ｂ側から基台３に熱が伝わるので、放熱が促進され、半導体受光素子１０の温度上昇が小さく抑制される。 The input light L1 passes through the heat transfer member 7 and the semiconductor substrate 11 of the semiconductor light receiving element 10 and enters the photodiode 12. A part of this input light L1 is converted into a current by photoelectric conversion and output, and the rest becomes heat, which increases the temperature of the semiconductor light receiving element 10. Most of the heat from the semiconductor light receiving element 10 is transferred to the base 3. The heat transfer path is a path that transfers to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and a path that transfers to the base 3 via the heat transfer member 7 on the second surface 11b side as shown by arrow H2. The only part of the path indicated by arrow H2 where heat transfer is difficult is the interface between the leg 7b of the heat transfer member 7 and the base 3, but the heat transfer is improved by, for example, a thermal conductive paste. The heat transferred to the base 3 is dissipated from the base 3 to the outside (air, etc.), and is also dissipated to the outside from the cover 5 fixed to the base 3. Heat is transferred to the base 3 from the first surface 11a and the second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation and minimizing the temperature rise of the semiconductor light receiving element 10.
　図４に示すように、伝熱部材７は、半導体受光素子１０に密着させる矩形平板状の本体部７ａと、この本体部７ａの外周に沿う脚部７ｃとが一体的に形成されたものであってもよい。伝熱部材７と基台３の接触面積が大きくなり、伝熱部材７を介して基台３に半導体受光素子１０の熱を一層伝え易くすることができる。脚部７ｃの内側には、出力端子部２ａ，２ｂと基板４を電気的に接続する部分を含めて半導体受光素子１０が搭載された基板４が収容される。また、図示を省略するが、伝熱部材７は、矩形平板状の本体部７ａの外周に沿うように複数の脚部が本体部７ａと一体的に形成されていてもよい。 As shown in FIG. 4, the heat transfer member 7 may be formed integrally with a rectangular flat body 7a that is in close contact with the semiconductor light receiving element 10 and legs 7c that run along the outer periphery of the body 7a. This increases the contact area between the heat transfer member 7 and the base 3, making it easier to transfer heat from the semiconductor light receiving element 10 to the base 3 via the heat transfer member 7. The inside of the legs 7c houses the substrate 4 on which the semiconductor light receiving element 10 is mounted, including the portion that electrically connects the output terminals 2a, 2b to the substrate 4. Although not shown, the heat transfer member 7 may have multiple legs that are formed integrally with the rectangular flat body 7a so as to run along the outer periphery of the body 7a.
　図５は、伝熱部材７を有する光給電コンバータ１に入力光Ｌ１を入力して１Ｗ（＝１Ｊ／ｓ）で発熱する場合に、伝熱部材７の本体部７ａの厚さｔと半導体受光素子１０の温度上昇幅ΔＴの関係を示すシミュレーション結果である。基台３の温度は一定温度に維持されている。厚さｔ＝０ｍｍは、伝熱部材７がない場合を示している。●は図２の２つの脚部７ｂを有するタイプ、◇は図４の脚部７ｃを有するタイプの伝熱部材７であり、伝熱部材７の本体部７ａの大きさは等しく、脚部７ｂの厚さと脚部７ｃの厚さは等しい。脚部の厚さとは、半導体受光素子１０から離隔する方向において、脚部の半導体受光素子１０に臨む側（内側）から、対向する側（外側）までの長さのことである。半導体受光素子１０と基板４の合計の厚さに相当する脚部７ｂ，７ｃの高さは例えば０．８ｍｍである。図４の脚部７ｃの基台３との接触面積は、図２の２つの脚部７ｂの基台３との接触面積の概ね２倍である。 Figure 5 shows the results of a simulation showing the relationship between the thickness t of the body 7a of the heat transfer member 7 and the temperature rise width ΔT of the semiconductor light receiving element 10 when input light L1 is input to the optical power supply converter 1 having the heat transfer member 7 and heats up at 1 W (= 1 J/s). The temperature of the base 3 is maintained at a constant temperature. The thickness t = 0 mm indicates the case where there is no heat transfer member 7. ● is the type having two legs 7b in Figure 2, and ◇ is the type having the leg 7c in Figure 4, where the body 7a of the heat transfer member 7 is the same in size, and the thickness of the leg 7b is the same as the thickness of the leg 7c. The thickness of the leg refers to the length from the side of the leg facing the semiconductor light receiving element 10 (inside) to the opposite side (outside) in the direction away from the semiconductor light receiving element 10. The height of the legs 7b and 7c, which corresponds to the total thickness of the semiconductor light receiving element 10 and the substrate 4, is, for example, 0.8 mm. The contact area of the leg 7c in FIG. 4 with the base 3 is approximately twice the contact area of the two legs 7b in FIG. 2 with the base 3.
　図５によれば、本体部７ａの厚さｔが０．８ｍｍ程度までは、本体部７ａが厚いほど半導体受光素子１０の温度上昇幅ΔＴが小さくなり、伝熱部材７を介して半導体受光素子１０の熱が基台３に伝わり易くなることがわかる。また、基台３との接触面積が大きい図４の脚部７ｃを有するタイプの方が、図２の２つの脚部７ｂを有するタイプよりも温度上昇幅ΔＴが小さくなり、伝熱性能が向上することがわかる。尚、本体部７ａの大きさ、半導体受光素子１０の大きさ等によって温度上昇幅ΔＴの値は変動するが、上記と同様の傾向になることが容易に推察される。 According to Figure 5, up to a thickness t of the main body 7a of about 0.8 mm, the thicker the main body 7a, the smaller the temperature rise ΔT of the semiconductor light receiving element 10, and the easier it is for heat from the semiconductor light receiving element 10 to be transferred to the base 3 via the heat transfer member 7. It can also be seen that the type with the leg 7c in Figure 4, which has a larger contact area with the base 3, has a smaller temperature rise ΔT than the type with two legs 7b in Figure 2, and thus has improved heat transfer performance. Note that the value of the temperature rise ΔT varies depending on the size of the main body 7a, the size of the semiconductor light receiving element 10, etc., but it can be easily inferred that the same tendency as above will be observed.
　図６に示すように、伝熱部材７が矩形平板状に形成され、基台３には半導体受光素子１０に密着させた伝熱部材７の両端部分が載置、固定される２つの支持部３ｃが、伝熱部材７に向かって基台３から突出するように基台３と一体的に形成されてもよい。この場合も、半導体受光素子１０の熱は、矢印Ｈ１で示すように第１面１１ａ側の基板４を介して基台３に伝わると共に、矢印Ｈ３で示すように半導体受光素子１０に密着させた第２面１１ｂ側の伝熱部材７と２つの支持部３ｃを介して基台３に伝わる。矢印Ｈ３の経路で伝熱し難いのは、伝熱部材７と支持部３ｃの界面のみであるが、支持部３ｃに伝熱部材７を固定する例えば熱伝導ペーストによって伝熱性を向上させている。半導体受光素子１０の面積が大きい第１面１１ａ側と第２面１１ｂ側から基台３に伝熱させることができるので、放熱が促進され、温度上昇が小さく抑制される。 6, the heat transfer member 7 is formed in a rectangular plate shape, and the two support parts 3c on which both ends of the heat transfer member 7 in close contact with the semiconductor light receiving element 10 are placed and fixed may be formed integrally with the base 3 so as to protrude from the base 3 toward the heat transfer member 7. In this case, too, the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and is also transferred to the base 3 via the heat transfer member 7 on the second surface 11b side that is in close contact with the semiconductor light receiving element 10 and the two support parts 3c as shown by arrow H3. The only place where heat transfer is difficult in the path of arrow H3 is the interface between the heat transfer member 7 and the support parts 3c, but the heat transfer is improved by, for example, a thermally conductive paste that fixes the heat transfer member 7 to the support parts 3c. Heat can be transferred to the base 3 from the first surface 11a and second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation and minimizing temperature rise.
　図７は、図６の伝熱部材７と基台３を有する光給電コンバータ１に１Ｗの入力光Ｌ１を入力した場合に、伝熱部材７の厚さｔと半導体受光素子１０の温度上昇幅ΔＴの関係を示すシミュレーション結果である。厚さｔ＝０ｍｍは、伝熱部材７がない場合である。支持部３ｃの大きさは図２の脚部７ｂと等しい。この場合も本体部７ａの厚さｔが０．８ｍｍ程度までは、伝熱部材７が厚いほど半導体受光素子１０の温度上昇幅ΔＴが小さくなり、伝熱部材７を介して半導体受光素子１０の熱が基台３に伝わり易くなることがわかる。図示を省略するが、矩形平板状に形成された伝熱部材７の外周に沿うように基台３から突出する支持部が、基台３と一体的に形成されてもよい。 Figure 7 shows the results of a simulation showing the relationship between the thickness t of the heat transfer member 7 and the temperature rise ΔT of the semiconductor light receiving element 10 when 1 W of input light L1 is input to the optical power supply converter 1 having the heat transfer member 7 and base 3 of Figure 6. The thickness t = 0 mm is the case when there is no heat transfer member 7. The size of the support 3c is equal to the leg 7b of Figure 2. In this case as well, it can be seen that up to a thickness t of about 0.8 mm of the main body 7a, the thicker the heat transfer member 7 is, the smaller the temperature rise ΔT of the semiconductor light receiving element 10 becomes, and the easier it is for the heat of the semiconductor light receiving element 10 to be transferred to the base 3 via the heat transfer member 7. Although not shown, the support protruding from the base 3 so as to follow the outer periphery of the heat transfer member 7 formed in a rectangular flat plate shape may be formed integrally with the base 3.
　図８に示すように、矩形平板状に形成された伝熱部材７の両端に、又は伝熱部材７の外周に沿うように、伝熱部材７よりも熱伝導性に優れた例えばアルミニウム又は銅を主成分とする金属製のスペーサ部材８が配設され、半導体受光素子１０に密着させた伝熱部材７がスペーサ部材８を介して基台３に固定されてもよい。この場合も、半導体受光素子１０の熱は、矢印Ｈ１で示すように第１面１１ａ側の基板４を介して基台３に伝わると共に、矢印Ｈ４で示すように第２面１１ｂ側の伝熱部材７とスペーサ部材８を介して基台３に伝わる。矢印Ｈ４の経路には、スペーサ部材８と伝熱部材７の界面とスペーサ部材８と基台３の界面があるが、例えば熱伝導ペーストによって伝熱性を向上させて、伝熱部材７から熱伝導性が高いスペーサ部材８を介して基台３に熱が伝わる。従って、半導体受光素子１０の面積が大きい第１面１１ａ側と第２面１１ｂ側から基台３に伝熱させることができるので、放熱が促進され、温度上昇が小さく抑制されると共に、伝熱部材７及び基台３の形成が容易になる。 8, metal spacer members 8 made of, for example, aluminum or copper, which have better thermal conductivity than the heat transfer member 7, may be disposed on both ends of the heat transfer member 7 formed in a rectangular plate shape, or along the outer periphery of the heat transfer member 7, and the heat transfer member 7 in close contact with the semiconductor light receiving element 10 may be fixed to the base 3 via the spacer members 8. In this case, too, the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the substrate 4 on the first surface 11a side as shown by arrow H1, and is transferred to the base 3 via the heat transfer member 7 and spacer member 8 on the second surface 11b side as shown by arrow H4. The path of arrow H4 includes the interface between the spacer member 8 and the heat transfer member 7 and the interface between the spacer member 8 and the base 3, but the heat transfer is improved by, for example, a thermally conductive paste, and the heat is transferred from the heat transfer member 7 to the base 3 via the spacer member 8, which has high thermal conductivity. Therefore, heat can be transferred to the base 3 from the first surface 11a and second surface 11b, which have larger areas of the semiconductor light receiving element 10, promoting heat dissipation, minimizing temperature rise, and facilitating the formation of the heat transfer member 7 and base 3.
　次に半導体受光素子１０について説明する。
　半導体受光素子１０のフォトダイオード１２は、半導体受光素子１０の出力電圧を高くするために、図９に示すように、フォトダイオード１２の中心Ｃから放射状に延びる複数の溝１３によって周方向に等分された複数のセグメントを有する。ここではフォトダイオード１２は８つに等分されているが、要求される電圧に応じて分割数は適宜設定される。複数のセグメントは１対の電極を夫々有し、各セグメントにおいて表面の大部分を覆う電極を第２電極１５とし、他方の電極を第１電極１４とする。 Next, the semiconductor light receiving element 10 will be described.
In order to increase the output voltage of the semiconductor light receiving element 10, the photodiode 12 of the semiconductor light receiving element 10 has a plurality of segments equally divided in the circumferential direction by a plurality of grooves 13 extending radially from the center C of the photodiode 12, as shown in Fig. 9. Here, the photodiode 12 is equally divided into eight segments, but the number of divisions is appropriately set according to the required voltage. Each of the plurality of segments has a pair of electrodes, and the electrode covering most of the surface of each segment is the second electrode 15, and the other electrode is the first electrode 14.
　フォトダイオード１２の隣り合うセグメント間で一方のセグメントの第１電極１４と他方のセグメントの第２電極１５とを接続して全セグメントを直列接続するために、図１０に示すように、半導体受光素子１０が搭載される基板４には配線部４ａが形成されている。配線部４ａは、各セグメントの第２電極１５に対応するように形成され且つ隣接するセグメントの第１電極１４に接続するように延びた配線パターンと、直列接続の両端となる部分に導電性ワイヤ６ａ，６ｂの接続用の配線パターンを備えている。 In order to connect all the segments in series between adjacent segments of the photodiode 12 by connecting the first electrode 14 of one segment with the second electrode 15 of the other segment, as shown in FIG. 10, a wiring section 4a is formed on the substrate 4 on which the semiconductor light receiving element 10 is mounted. The wiring section 4a is formed to correspond to the second electrode 15 of each segment and has a wiring pattern that extends to connect to the first electrode 14 of the adjacent segment, and has wiring patterns for connecting the conductive wires 6a, 6b at both ends of the series connection.
　基板４の配線部４ａに対して、対応する半導体受光素子１０の複数の第１、第２電極１４，１５が位置合わせされ、例えば鉛を含まないソルダーペーストによって接続される。これにより、半導体受光素子１０が基板４に固定されると共に、複数のセグメントが直列接続されたフォトダイオード１２が形成される。図１１は、この直列接続されたフォトダイオード１２の要部断面図であり、図９及び図１０のＸＩ－ＸＩ線に対応する断面図である。 The multiple first and second electrodes 14, 15 of the semiconductor light receiving element 10 are aligned with the corresponding wiring portion 4a of the substrate 4 and connected, for example, by a lead-free solder paste. This fixes the semiconductor light receiving element 10 to the substrate 4 and forms a photodiode 12 in which multiple segments are connected in series. Figure 11 is a cross-sectional view of a main part of this series-connected photodiode 12, and is a cross-sectional view corresponding to the XI-XI line in Figures 9 and 10.
　フォトダイオード１２を構成する複数のセグメントは、半導体基板１１の第１面１１ａ側に、第１半導体層１６と光吸収層１７と第２半導体層１８が積層されて形成された円形のＰＩＮフォトダイオードが複数の溝１３によって周方向に等分されて形成されている。そして、溝１３内と第２半導体層１８を覆う絶縁層１９が形成され、絶縁層１９に形成された開口部を介して第２半導体層１８に接続される第２電極１５が、第２半導体層１８の大部分を覆うように形成されている。また、第１電極１４は、第２半導体層１８と光吸収層１７を貫通する接続孔を介して第１半導体層１６に接続されている。尚、接続孔の内壁にも絶縁層１９が形成されている。 The multiple segments constituting the photodiode 12 are formed on the first surface 11a side of the semiconductor substrate 11, with a circular PIN photodiode formed by stacking a first semiconductor layer 16, a light absorbing layer 17, and a second semiconductor layer 18, and divided equally in the circumferential direction by multiple grooves 13. An insulating layer 19 is formed to cover the inside of the grooves 13 and the second semiconductor layer 18, and a second electrode 15 connected to the second semiconductor layer 18 through an opening formed in the insulating layer 19 is formed so as to cover most of the second semiconductor layer 18. The first electrode 14 is connected to the first semiconductor layer 16 through a connection hole that penetrates the second semiconductor layer 18 and the light absorbing layer 17. An insulating layer 19 is also formed on the inner wall of the connection hole.
　半導体基板１１は例えば半絶縁性のＩｎＰ基板であり、第１半導体層１６は例えばｎ－ＩｎＰ層である。光吸収層１７は例えばＩｎＧａＡｓ層であり、第２半導体層１８は例えばｐ－ＩｎＰ層であり、絶縁層１９は例えばＳｉＯ２層である。第１、第２電極１４，１５は、例えば金を主成分とする金属で形成されている。基板４の配線部４ａは、例えば金又は銅を主成分とする金属で形成されている。第１、第２電極１４，１５と対応する配線部４ａとは、ソルダーペースト２０によって接続されている。 The semiconductor substrate 11 is, for example, a semi-insulating InP substrate, and the first semiconductor layer 16 is, for example, an n-InP layer. The light absorbing layer 17 is, for example, an InGaAs layer, the second semiconductor layer 18 is, for example, a p-InP layer, and the insulating layer 19 is, for example, a SiO2 layer. The first and second electrodes 14, 15 are formed of a metal containing, for example, gold as a main component. The wiring portion 4a of the substrate 4 is formed of a metal containing, for example, gold or copper as a main component. The first and second electrodes 14, 15 and the corresponding wiring portion 4a are connected by solder paste 20.
　光ファイバケーブルＯＣは、入力光Ｌ１の光軸ＯＡがフォトダイオード１２に対して垂直に且つフォトダイオード１２の中心Ｃを通るように固定される。周方向に等分された複数のセグメントが直列接続されたフォトダイオード１２は入力光Ｌ１によって発熱し、半導体受光素子１０の温度が上昇する。この温度上昇を小さく抑えるために、半導体受光素子１０に密着させる伝熱部材７が配設されている。 The optical fiber cable OC is fixed so that the optical axis OA of the input light L1 is perpendicular to the photodiode 12 and passes through the center C of the photodiode 12. The photodiode 12, which has multiple segments connected in series and equally spaced circumferentially, generates heat in response to the input light L1, causing the temperature of the semiconductor light receiving element 10 to rise. To keep this temperature rise to a minimum, a heat transfer member 7 is provided in close contact with the semiconductor light receiving element 10.
　ここで、図１２に示すように、光ファイバケーブルＯＣを介して入力される入力光Ｌ１は円錐状に広がる。この入力光Ｌ１の光強度分布は、入力光Ｌ１の光軸ＯＡから離隔するほど光強度が低下すると共に光軸ＯＡを中心とした回転対称状のガウス分布になる。しかし、フォトダイオード１２は、その中心Ｃから光軸ＯＡに対して直交する方向に放射状に延びる複数の溝１３を有し、この溝１３では光電変換できないので、複数の溝１３が集中する中心Ｃ近傍では光軸ＯＡ近傍の光強度が高い部分を利用できなくなる。 Here, as shown in FIG. 12, the input light L1 input through the optical fiber cable OC spreads out in a cone shape. The light intensity distribution of this input light L1 decreases the further away from the optical axis OA of the input light L1, and becomes a Gaussian distribution that is rotationally symmetrical about the optical axis OA. However, the photodiode 12 has multiple grooves 13 that extend radially from its center C in a direction perpendicular to the optical axis OA, and since photoelectric conversion is not possible in these grooves 13, the areas of high light intensity near the optical axis OA cannot be used near the center C where the multiple grooves 13 are concentrated.
　そこで、図１３、図１４に示すように、伝熱部材７の入力光Ｌ１が照射される領域に、円錐状の凹面７ｄを形成する。この凹面７ｄは、伝熱部材７の矩形平板状の本体部７ａの半導体受光素子１０に密着させる面と反対側の面を円錐状に凹入させて形成される。例えば公知のエッチング技術によって円錐状の凹面７ｄが形成されてもよく、研磨によって円錐状の凹面７ｄが形成されてもよい。 Therefore, as shown in Figures 13 and 14, a conical concave surface 7d is formed in the area of the heat transfer member 7 where the input light L1 is irradiated. This concave surface 7d is formed by conically recessing the surface of the rectangular, flat body portion 7a of the heat transfer member 7 opposite the surface that is brought into close contact with the semiconductor light receiving element 10. For example, the conical concave surface 7d may be formed by a known etching technique, or the conical concave surface 7d may be formed by polishing.
　円錐状の凹面７ｄを有する伝熱部材７は、入力光Ｌ１の光軸ＯＡが円錐状の凹面７ｄの頂点を通る対称軸に一致し且つフォトダイオード１２の中心Ｃを通るように、半導体受光素子１０に対して位置決めされて基台３に固定される。これにより入力光Ｌ１は円錐状の凹面７ｄによって光軸ＯＡから離隔するように広がり、円形の照射領域が円環状になる。そして、フォトダイオード１２には、照射領域が円環状になった光が入射する。 The heat transfer member 7, which has a conical concave surface 7d, is positioned relative to the semiconductor light receiving element 10 and fixed to the base 3 so that the optical axis OA of the input light L1 coincides with the axis of symmetry passing through the apex of the conical concave surface 7d and passes through the center C of the photodiode 12. As a result, the input light L1 spreads away from the optical axis OA by the conical concave surface 7d, and the circular irradiation area becomes annular. Then, the light with the annular irradiation area is incident on the photodiode 12.
　円錐状の凹面７ｄを有する伝熱部材７によって、入力光Ｌ１は放射状の複数の溝１３が集まるフォトダイオード１２の中心Ｃ近傍には入射しないので、入力光Ｌ１を有効に利用することができる。また、半導体受光素子１０の熱が基板４を介してだけでなく伝熱部材７を介して基台３に伝えられるので、半導体受光素子１０の放熱が促進され、半導体受光素子１０の温度上昇が抑制される。尚、円錐状の凹面７ｄは、図４、図６又は図８のタイプの伝熱部材７にも形成することができる。 The heat transfer member 7 having a conical concave surface 7d prevents the input light L1 from entering near the center C of the photodiode 12 where the multiple radial grooves 13 gather, allowing the input light L1 to be used effectively. In addition, the heat of the semiconductor light receiving element 10 is transferred to the base 3 not only through the substrate 4 but also through the heat transfer member 7, promoting heat dissipation from the semiconductor light receiving element 10 and suppressing a rise in temperature of the semiconductor light receiving element 10. The conical concave surface 7d can also be formed on the heat transfer member 7 of the type shown in FIG. 4, FIG. 6, or FIG. 8.
　図１５には、光給電コンバータのある温度（例えば室温）での出力特性が曲線Ａ１で示され、温度上昇したときの出力特性が曲線Ａ２で示されている。温度上昇によって最大出力電力Ｐｍａｘが原点に近づく方向にシフトする、即ち最大出力電力Ｐｍａｘが低下する。伝熱部材７を備えた光給電コンバータ１は、半導体受光素子１０の熱の一部を伝熱部材７によって基台３に伝えることによって放熱を促進させて、温度上昇を小さくすることができるので、このような出力低下が小さくなる。 In Figure 15, curve A1 shows the output characteristics of the optical power converter at a certain temperature (e.g. room temperature), and curve A2 shows the output characteristics when the temperature rises. An increase in temperature causes the maximum output power Pmax to shift closer to the origin, i.e. the maximum output power Pmax decreases. The optical power converter 1 equipped with the heat transfer member 7 can reduce the temperature rise by promoting heat dissipation by transferring some of the heat from the semiconductor light receiving element 10 to the base 3 via the heat transfer member 7, thereby reducing this decrease in output.
　上記光給電コンバータ１の作用、効果について説明する。
　光ファイバケーブルＯＣを介して光給電コンバータ１に入力される入力光Ｌ１は、半導体受光素子１０に密着させた伝熱部材７を透過してこの半導体受光素子１０に入射し、半導体受光素子１０の熱の一部が伝熱部材７を介して基台３に伝わる。従って、半導体受光素子１０の熱が、フォトダイオード１２が形成された第１面１１ａ側から基台３に伝わるだけでなく、第２面１１ｂ側からも伝熱部材７を介して基台３に伝わる。それ故、半導体受光素子１０の放熱を促進させて温度上昇を小さくすることができ、光給電コンバータ１の出力低下を抑制することができる。 The operation and effects of the optical power supply converter 1 will now be described.
The input light L1 input to the optical power supply converter 1 via the optical fiber cable OC passes through the heat transfer member 7 that is in close contact with the semiconductor light receiving element 10 and enters the semiconductor light receiving element 10, and a part of the heat of the semiconductor light receiving element 10 is transferred to the base 3 via the heat transfer member 7. Therefore, the heat of the semiconductor light receiving element 10 is transferred to the base 3 not only from the first surface 11a side on which the photodiode 12 is formed, but also from the second surface 11b side to the base 3 via the heat transfer member 7. Therefore, it is possible to promote heat dissipation from the semiconductor light receiving element 10, reduce a temperature rise, and suppress a decrease in the output of the optical power supply converter 1.
　基台３に固定される脚部７ｂが伝熱部材７と一体的に形成されている場合には、一般的に伝熱し難くなる界面が脚部７ｂと基台３の界面のみになり、基台３に熱を伝え易くすることができる。一方、伝熱部材７が固定される支持部３ｃが基台３と一体的に形成されている場合には、伝熱し難い界面が伝熱部材７と支持部３ｃの界面のみになり、基台３に熱を伝え易くすることができる。また、熱伝導性に優れた材料で形成されたスペーサ部材８を介して伝熱部材７を基台３に固定した場合には、基台３に熱を伝え易くすることができると共に、伝熱部材７及び基台３の形成が容易になる。 When the legs 7b fixed to the base 3 are formed integrally with the heat transfer member 7, the only interface where heat transfer is generally difficult is the interface between the legs 7b and the base 3, making it easier to transfer heat to the base 3. On the other hand, when the support 3c to which the heat transfer member 7 is fixed is formed integrally with the base 3, the only interface where heat transfer is difficult is the interface between the heat transfer member 7 and the support 3c, making it easier to transfer heat to the base 3. In addition, when the heat transfer member 7 is fixed to the base 3 via a spacer member 8 made of a material with excellent thermal conductivity, it is easier to transfer heat to the base 3 and it becomes easier to form the heat transfer member 7 and the base 3.
　出力電圧を高くするために、フォトダイオード１２は、その中心Ｃから放射状に延びる複数の溝１３によって等分された複数のセグメントが直列接続されて形成されている。光ファイバケーブルＯＣからの入力光Ｌ１の照射領域は円形であり、その光強度分布は光軸ＯＡから離隔するほど光強度が低下すると共に光軸ＯＡに対して回転対称である。それ故、複数のセグメントに均等に入射させるために、入力光Ｌ１は、その光軸ＯＡがフォトダイオード１２の中心Ｃを通るように入力される。フォトダイオード１２の中心Ｃ近傍には光電変換できない溝１３が集中しているので、入力光Ｌ１の光軸ＯＡ近傍の光強度が高い部分が光電変換されず無駄が大きくなる。しかし、伝熱部材７の入力光Ｌ１が照射される領域に円錐状の凹面７ｄが形成されている場合には、この凹面７ｄに入射した入力光Ｌ１の円形の照射領域が円環状に変換されてフォトダイオード１２に入射する。従って、溝１３が集中するフォトダイオード１２の中心Ｃ近傍を避けて入力光Ｌ１の光強度が高い部分をフォトダイオード１２に入射させ、入力光Ｌ１を有効に利用することができる。 In order to increase the output voltage, the photodiode 12 is formed by connecting multiple segments in series, each segment being equally divided by multiple grooves 13 extending radially from its center C. The irradiation area of the input light L1 from the optical fiber cable OC is circular, and its light intensity distribution is rotationally symmetrical with respect to the optical axis OA, with the light intensity decreasing the farther away from the optical axis OA. Therefore, in order to make the input light L1 evenly incident on the multiple segments, the input light L1 is input so that its optical axis OA passes through the center C of the photodiode 12. Since the grooves 13 that cannot be photoelectrically converted are concentrated near the center C of the photodiode 12, the part of the input light L1 with high light intensity near the optical axis OA is not photoelectrically converted, resulting in a large amount of waste. However, if a conical concave surface 7d is formed in the area of the heat transfer member 7 where the input light L1 is irradiated, the circular irradiation area of the input light L1 incident on this concave surface 7d is converted into an annular shape and incident on the photodiode 12. Therefore, the part of the input light L1 with high light intensity is made incident on the photodiode 12, avoiding the vicinity of the center C of the photodiode 12 where the grooves 13 are concentrated, and the input light L1 can be used effectively.
　基板４は、絶縁層とこの絶縁層上に配線部４ａを備えたシリコン基板であってもよい。また、基板４の配線部４ａが基台３の絶縁層上に形成され、基板４を省略して基台３に半導体受光素子１０が固定され、放熱を促進させるようにしてもよい。その他、当業者であれば、本発明の趣旨を逸脱することなく、上記実施形態に種々の変更を付加した形態で実施可能であり、本発明はその種の変更形態も包含するものである。 The substrate 4 may be a silicon substrate having an insulating layer and a wiring portion 4a on the insulating layer. Alternatively, the wiring portion 4a of the substrate 4 may be formed on the insulating layer of the base 3, and the substrate 4 may be omitted and the semiconductor light receiving element 10 may be fixed to the base 3 to promote heat dissipation. In addition, a person skilled in the art may implement the above embodiment in various modified forms without departing from the spirit of the present invention, and the present invention also includes such modified forms.
１　　：光給電コンバータ
２ａ，２ｂ：出力端子部
３　　：基台
３ｃ　：支持部
４　　：基板
４ａ　：配線部
５　　：カバー
５ａ　：開口部
６ａ，６ｂ：導電性ワイヤ
７　　：伝熱部材
７ａ　：本体部
７ｂ，７ｃ：脚部
７ｄ　：凹面
８　　：スペーサ部材
１０　：半導体受光素子
１１　：半導体基板
１１ａ：第１面
１１ｂ：第２面
１２　：フォトダイオード
１３　：溝
１４　：第１電極
１５　：第２電極
１６　：第１半導体層
１７　：光吸収層
１８　：第２半導体層
１９　：絶縁層
２０　：ソルダーペースト
Ｌ１　：入力光
ＯＡ　：光軸
ＯＣ　：光ファイバケーブル 1: Optical power supply converter 2a, 2b: Output terminal section 3: Base 3c: Support section 4: Substrate 4a: Wiring section 5: Cover 5a: Openings 6a, 6b: Conductive wire 7: Heat transfer member 7a: Main body 7b, 7c: Leg section 7d: Concave surface 8: Spacer member 10: Semiconductor light receiving element 11: Semiconductor substrate 11a: First surface 11b: Second surface 12: Photodiode 13: Groove 14: First electrode 15: Second electrode 16: First semiconductor layer 17: Light absorbing layer 18: Second semiconductor layer 19: Insulating layer 20: Solder paste L1: Input light OA: Optical axis OC: Optical fiber cable

Claims (5)

  1. 　光ファイバケーブルを介して入力される入力光を光電変換する半導体受光素子と、前記半導体受光素子を固定するための基台を有する光給電コンバータにおいて、
    　前記半導体受光素子は、前記入力光に対して透明な半導体基板の第１面側にフォトダイオードを備え、且つ前記第１面側が前記基台に固定され、
    　前記入力光に対して透明な伝熱部材であって、前記半導体基板の前記第１面に対向する第２面側に密着させた伝熱部材が前記基台に固定され、
    　前記入力光が前記伝熱部材を透過して前記半導体受光素子に入射するように構成されると共に、前記半導体受光素子の熱の一部が前記伝熱部材を介して前記基台に伝わるように構成されたことを特徴とする光給電コンバータ。     1. An optical power supply converter having a semiconductor light receiving element for photoelectrically converting light inputted through an optical fiber cable, and a base for fixing the semiconductor light receiving element,
    the semiconductor light receiving element includes a photodiode on a first surface side of a semiconductor substrate transparent to the input light, and the first surface side is fixed to the base;
    a heat transfer member that is transparent to the input light and is in close contact with a second surface side of the semiconductor substrate that faces the first surface, the heat transfer member being fixed to the base;
    An optical power supply converter characterized in that the input light is configured to pass through the heat transfer member and be incident on the semiconductor light receiving element, and a portion of the heat of the semiconductor light receiving element is configured to be transferred to the base via the heat transfer member.
  2. 　前記伝熱部材には、前記基台に向かって延びてこの基台に固定される脚部が一体的に形成されたことを特徴とする請求項１に記載の光給電コンバータ。 The optical power converter according to claim 1, characterized in that the heat transfer member is integrally formed with legs that extend toward the base and are fixed to the base.
  3. 　前記基台には、前記伝熱部材に向かって延びてこの伝熱部材が固定される支持部が一体的に形成されたことを特徴とする請求項１に記載の光給電コンバータ。 The photovoltaic converter according to claim 1, characterized in that the base is integrally formed with a support portion that extends toward the heat transfer member and to which the heat transfer member is fixed.
  4. 　前記伝熱部材は、スペーサ部材を介して前記基台に固定されたことを特徴とする請求項１に記載の光給電コンバータ。 The optical power converter according to claim 1, characterized in that the heat transfer member is fixed to the base via a spacer member.
  5. 　前記フォトダイオードは、前記入力光の光軸が通る中心からこの光軸に直交する方向に放射状に延びる溝によって等分された複数のセグメントが直列接続されて形成され、
    　前記伝熱部材は、前記半導体基板の前記第２面側に密着させる接触面と反対側の前記入力光が照射される領域に、前記光軸に対称軸が一致するように形成された円錐状の凹面を備えたことを特徴とする請求項１に記載の光給電コンバータ。
          the photodiode is formed by connecting in series a plurality of equal segments divided by grooves extending radially from a center through which an optical axis of the input light passes in a direction perpendicular to the optical axis,
    The optical power supply converter according to claim 1, characterized in that the heat transfer member has a conical concave surface formed so that its axis of symmetry coincides with the optical axis in an area where the input light is irradiated on the opposite side of the contact surface that is in close contact with the second surface side of the semiconductor substrate.
PCT/JP2022/041024 2022-11-02 2022-11-02 Optical electric power supply converter WO2024095405A1 (en)

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PCT/JP2022/041024 WO2024095405A1 (en) 2022-11-02 2022-11-02 Optical electric power supply converter

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006295222A (en) * 2006-07-20 2006-10-26 Sumitomo Electric Ind Ltd Semiconductor light receiving element module
JP2008304611A (en) * 2007-06-06 2008-12-18 Fujikura Ltd Optical transmitter/receiver
JP2010114235A (en) * 2008-11-06 2010-05-20 Nec Corp Photoelectric transducer, optical power supply, and method for manufacturing photoelectric transducer
US20110108081A1 (en) * 2006-12-20 2011-05-12 Jds Uniphase Corporation Photovoltaic Power Converter
JP6795870B1 (en) * 2020-07-06 2020-12-02 株式会社京都セミコンダクター Optical power converter
JP6836300B1 (en) * 2020-09-10 2021-02-24 株式会社京都セミコンダクター Surface-incident semiconductor light receiving element

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2006295222A (en) * 2006-07-20 2006-10-26 Sumitomo Electric Ind Ltd Semiconductor light receiving element module
US20110108081A1 (en) * 2006-12-20 2011-05-12 Jds Uniphase Corporation Photovoltaic Power Converter
JP2008304611A (en) * 2007-06-06 2008-12-18 Fujikura Ltd Optical transmitter/receiver
JP2010114235A (en) * 2008-11-06 2010-05-20 Nec Corp Photoelectric transducer, optical power supply, and method for manufacturing photoelectric transducer
JP6795870B1 (en) * 2020-07-06 2020-12-02 株式会社京都セミコンダクター Optical power converter
JP6836300B1 (en) * 2020-09-10 2021-02-24 株式会社京都セミコンダクター Surface-incident semiconductor light receiving element

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