Optical transceiver

Abstract

A Peltier element (PD) includes a first aluminum nitride substrate (211), a second aluminum nitride substrate (212), and a body part (301) supported therebetween. The body part (301) includes at least one semiconductor member (30), at least one first metal member (35), and at least one second metal member (35) sandwiching the at least one semiconductor member with the at least one first metal member. A laser chip (101) is mounted on a first surface of the first aluminum nitride substrate (211). A lens (110) is disposed apart from the first aluminum nitride substrate (211) in a planar layout, and is disposed so as to intersect a virtual plane (IP) including the first surface. A wiring pattern (280) is electrically connected to the laser chip (101) and is provided directly on the first surface.

Description

Optical Transceiver

[0001] The present invention relates to an optical transceiver.

[0002] Japanese Patent Laid-Open Publication No. 2006-229067 (Patent Document 1) discloses an optical transceiver module for transmitting and receiving signal light to and from an optical fiber. This optical transceiver module includes a laser diode that generates the signal light, a Peltier element for adjusting the temperature of the laser diode, and a package that houses the laser diode and the Peltier element.

[0003] U.S. Patent Application Publication No. 2021 / 0063685 (Patent Document 2) discloses several forms of optical devices, one form of which includes a housing having an optical aperture, an optical component disposed within the housing for emitting or receiving light through the aperture, and a cooling element thermally coupled to the housing for providing a constant temperature environment for the optical component.

[0004] JP 2006-229067 A U.S. Patent Application Publication No. 2021 / 0063685

[0005] In recent years, there has been a demand for reducing the power consumption, size, and material costs of optical transceivers. However, sufficient consideration has not been given to the cooling configurations of optical transceivers from these perspectives.

[0006] The present disclosure has been made to solve the above problems, and one object of the present disclosure is to provide an optical transceiver that can reduce the energy consumption associated with cooling of the optical transceiver. Another object of the present disclosure is to provide an optical transceiver that can reduce the size of the optical transceiver including the cooling configuration. Still another object of the present disclosure is to provide an optical transceiver that can reduce the material costs associated with cooling.

[0007] Aspect 1 is an optical transceiver for emitting output light in response to an input electrical signal, the Peltier element comprising: a first aluminum nitride substrate having a single-layer structure and having a first surface and a second surface opposite to the first surface; a second aluminum nitride substrate having a single-layer structure and disposed apart from the first aluminum nitride substrate in one direction and facing the second surface; and a body supported between the first aluminum nitride substrate and the second aluminum nitride substrate, the body comprising at least one semiconductor member, at least one first metal member in contact with the at least one semiconductor member, and a metal member in contact with the at least one semiconductor member and the at least one first metal member. and at least one second metal member sandwiching the at least one semiconductor member therebetween, and the optical transceiver further includes a laser chip for generating laser light mounted on the first surface of the first aluminum nitride substrate of the Peltier element, a lens positioned away from the first aluminum nitride substrate in a planar layout perpendicular to the one direction, positioned so as to intersect with an imaginary plane including the first surface of the first aluminum nitride substrate of the Peltier element, and positioned so as to allow the laser light from the laser chip to pass through, and a wiring pattern electrically connected to the laser chip and provided directly on the first surface of the first aluminum nitride substrate.

[0008] Aspect 2 is the optical transceiver according to aspect 1, wherein the first surface of the first aluminum nitride substrate is a flat surface.

[0009] Aspect 3 is the optical transceiver according to aspect 1 or 2, further comprising a heat sink made of metal and supporting the second aluminum nitride substrate.

[0010] Aspect 4 is an optical transceiver for emitting output light in response to an input electrical signal, comprising: a laser chip for generating laser light; a lens disposed apart from the laser chip in a planar layout and disposed so that the laser light from the laser chip passes through; and at least one aluminum nitride substrate, wherein the at least one aluminum nitride substrate includes a first aluminum nitride substrate having a first surface on which the laser chip is mounted and a second surface opposite to the first surface, and both of the at least one aluminum nitride substrates are disposed apart from the lens in a planar layout, and the optical transceiver The optical transceiver further comprises a support substrate supporting the first aluminum nitride substrate, the support substrate including at least one metal via and an insulator layer in which the at least one metal via is embedded, the at least one metal via having a first end directed toward the first aluminum nitride substrate and a second end opposite to the first end, the first end of the at least one metal via at least partially overlapping the first aluminum nitride substrate in a planar layout, the optical transceiver further comprises a cooler connected to the second end of the at least one metal via, and the first aluminum nitride substrate is not provided with any metal vias.

[0011] Aspect 5 is the optical transceiver according to aspect 4, wherein the cooler includes a Peltier element.

[0012] Aspect 6 is an optical transceiver according to aspect 5, wherein the Peltier element has at least one semiconductor element, and either all of the at least one semiconductor element are p-type and the at least one semiconductor element does not include an n-type semiconductor element, or all of the at least one semiconductor element are n-type and the at least one semiconductor element does not include a p-type semiconductor element, and the at least one semiconductor element has a surface to be bonded to a metal material, and the surface to be bonded is electrically connected to the at least one metal via.

[0013] Aspect 7 is an optical transceiver described in any one of aspects 4 to 6, wherein the support substrate has at least one through hole, and the at least one metal via completely fills the at least one through hole.

[0014] Aspect 8 is the optical transceiver according to any one of aspects 4 to 7, wherein the lens is supported by the support substrate, and the insulating layer of the support substrate is made of alumina.

[0015] Aspect 9 is an optical transceiver for emitting output light in response to an input electrical signal, comprising: a laser chip for generating laser light; and a support substrate supporting the laser chip, wherein the support substrate includes at least one metal via and an insulator layer in which the at least one metal via is embedded, the at least one metal via having a first end directed toward the laser chip and a second end opposite the first end; the optical transceiver further comprises a cooler connected to the second end of the at least one metal via; the laser chip is mounted on the support substrate and is positioned in front of the support substrate in a planar layout; The first end of the at least one metal via at least partially overlaps the laser chip, the cooler includes a Peltier element having at least one semiconductor member, each of the at least one semiconductor member having a p-type and the at least one semiconductor member not including an n-type semiconductor member, or each of the at least one semiconductor member having an n-type and the at least one semiconductor member not including a p-type semiconductor member, the at least one semiconductor member having a joining surface joined with a metal material, the joining surface being electrically connected to the at least one metal via.

[0016] According to the present disclosure, it is possible to reduce the energy consumption associated with cooling of an optical transceiver, reduce the size of the optical transceiver including the cooling configuration, and reduce the cost of components associated with cooling.

[0017] The objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

[0018] 16 is a block diagram showing a schematic configuration of an optical transceiver; FIG. 17 is a cross-sectional view showing a schematic configuration of an optical transceiver in a comparative example; FIG. 18 is a plan view showing a laser chip in the optical transceiver and a wiring pattern, components, and a temperature sensor arranged around the laser chip; FIG. 19 is a cross-sectional view showing a schematic configuration of an optical transceiver in a first embodiment; FIG. 19 is a cross-sectional view showing a schematic configuration of an optical transceiver in a second embodiment; FIG. 19 is a cross-sectional view showing a schematic configuration of an optical transceiver in a third embodiment; FIG. 20 is a cross-sectional view showing a schematic configuration of an optical transceiver in a fourth embodiment; FIG. 21 is a cross-sectional view showing a schematic configuration of an optical transceiver in a fifth embodiment; FIG. 22 is a cross-sectional view showing a schematic configuration of an optical transceiver in a sixth embodiment; FIG. 23 is a cross-sectional view showing a schematic configuration of an optical transceiver in a seventh embodiment; FIG. 24 is a perspective view showing simulation conditions for a comparative example; FIG. 25 is a side view showing simulation conditions for a comparative example; FIG. 26 is a perspective view showing simulation conditions for Example A; FIG. 27 is a side view showing simulation conditions for Example A; FIG. 28 is a perspective view showing simulation conditions for Example B; FIG. 29 is a side view showing simulation conditions for Example B; FIG. 29 is a cross-sectional view of Example B corresponding to the field of view of FIG. 15; 15A and 15B are partial perspective views showing the simulation conditions of Example B; FIG. 16A is a perspective view showing heat dissipation points under the simulation conditions of Example B; FIG. 16B is a cross-sectional view showing the simulation results of temperature distribution for a comparative example; FIG. 16C is a cross-sectional view showing the simulation results of temperature distribution for Example A; FIG. 16D is a cross-sectional view showing the simulation results of temperature distribution for Example B; FIG. 16F is a cross-sectional view showing the simulation results of heat flux distribution for a comparative example; FIG. 16G is a cross-sectional view showing the simulation results of heat flux distribution for Example A; FIG. 16H is a cross-sectional view showing the simulation results of heat flux distribution for Example B;

[0019] 1 is a block diagram showing a schematic configuration of an optical transceiver 1000. The optical transceiver 1000 has a transmitter optical subassembly (TOSA) 910, a receiver optical subassembly (ROSA) 920, an electrical circuit 930, and a housing that houses these components.

[0020] The TOSA 910 outputs an optical transmission signal SLT in response to an electrical signal from the electrical circuit 930. The TOSA 910 has a laser chip as a light-emitting element for generating the optical transmission signal SLT. The laser chip is, for example, an EML (Electro-absorption Modulator Laser Diode) laser chip.

[0021] The ROSA 920 outputs an electrical signal to the electrical circuit 930 in response to the optical reception signal SLR. The ROSA 920 has a light receiving element for converting the optical reception signal SLR into an electrical signal. The light receiving element is, for example, a photodiode element.

[0022] The electrical circuit 930 outputs an electrical signal for controlling the TOSA 910 in response to the input electrical signal SEI. The electrical circuit 930 also outputs an output electrical signal SEO in response to an electrical signal from the ROSA 920. The electrical circuit 930 may include a DSP (Digital Signal Processor) for processing signals to or from the TOSA 910. The electrical circuit 930 may also include a driver for driving the laser chip of the TOSA 910, in other words, a laser driver. The laser driver may be provided between the TOSA 910 and the DSP. The electrical circuit 930 may also include a microcontroller unit (MCU) (microcontroller). The electrical circuit 930 may also include a power supply.

[0023] As described above, the optical transceiver 1000 is configured to emit an optical transmission signal SLT (output light) in response to an input electrical signal SEI, and to output an output electrical signal SEO in response to an optical reception signal SLR (input light).

[0024] The comparative example and each embodiment described below also have the above-described configuration in common, and description of this configuration will not be repeated.

[0025] 2 is a cross-sectional view showing a schematic configuration of a comparative example optical transceiver 1001. Optical transceiver 1001 includes laser chip 101, lens 110, and a plurality of aluminum nitride substrates 201 to 203 as aluminum nitride substrates 200.

[0026] The laser chip 101 generates laser light LL. The lens 110 is positioned away from the laser chip 101 in the planar layout, and this also applies to each embodiment described below. In this specification, the planar layout refers to a layout in a plane perpendicular to the thickness direction (the vertical direction in FIG. 2 ). The lens 110 is positioned so that the laser light LL from the laser chip 101 passes through it. In the figure, the dashed-dotted line represents the optical axis of the laser light LL. The aluminum nitride substrate 201 has an upper surface on which the laser chip 101 is mounted and an opposite lower surface. The aluminum nitride substrate 202 has an upper surface that supports the lower surface of the aluminum nitride substrate 201 and an opposite lower surface. The lens 110 is stacked on the upper surface of the aluminum nitride substrate 202 without being separated by any of the aluminum nitride substrates 200. Meanwhile, the laser chip 101 is stacked on the upper surface of the aluminum nitride substrate 202, separated by an aluminum nitride substrate 203.

[0027] The optical transceiver 1001 has a Peltier element PD (cooler). The Peltier element PD has a pair of aluminum nitride substrates and a main body 301 supported therebetween. In this embodiment, the pair of aluminum nitride substrates are aluminum nitride substrate 202 and aluminum nitride substrate 203. The aluminum nitride substrate 202 of the Peltier element PD may be adhered to the aluminum nitride substrate 201 by an adhesive layer (not shown) made of a material other than aluminum nitride, such as a silicone adhesive sheet. The aluminum nitride substrate 203 of the Peltier element PD may be adhered to the heat sink 511 by an adhesive layer (not shown) made of a material other than aluminum nitride, such as a silicone adhesive sheet.

[0028] The main body 301 of the Peltier element PD is attached to the underside of the aluminum nitride substrate 202 to cool the laser chip 101. The main body 301 has a plurality of semiconductor members 30 and a plurality of metal members 35. The plurality of metal members 35 includes at least one metal member (first metal member) arranged on one side (upper side in FIG. 2 ) in the thickness direction (vertical direction in FIG. 2 ) and at least one metal member (second metal member) arranged on the other side (lower side in FIG. 2 ) in the thickness direction. Each of the semiconductor members 30 is sandwiched between the metal members 35. Each of the first and second metal members contacts the semiconductor member 30. The first and second metal members sandwich the semiconductor member 30 in the thickness direction. The plurality of semiconductor members 30 has a p-type semiconductor member 31 and an n-type semiconductor member 32. The p-type semiconductor members 31 and the n-type semiconductor members 32 are alternately connected in series via the metal members 35. The aluminum nitride substrate 203 and the aluminum nitride substrate 202 sandwich the main body 301. In other words, the main body 301 is disposed between the aluminum nitride substrate 202 and the aluminum nitride substrate 203. As a result, the main body 301 is supported between the aluminum nitride substrate 202 and the aluminum nitride substrate 203.

[0029] The optical transceiver 1001 has a heat sink 511. The heat sink 511 supports the aluminum nitride substrate 203. The heat sink 511 is made of metal, such as stainless steel (SUS). The heat sink 511, together with a wall 512 and a lid 513, constitutes a housing 510 having a sealed internal space.

[0030] The optical transceiver 1001 has a wiring substrate 410. The wiring substrate 410 has an insulator layer 411 and a wiring pattern 412 provided on the insulator layer 411. The insulator layer 411 may be made of an inexpensive material other than aluminum nitride, such as alumina. The laser chip 101 is electrically connected to the wiring pattern 412. The wiring substrate 410 has a portion that protrudes outside the housing 510, and the wiring pattern 412 is exposed at this portion. The wiring pattern 412 and the housing 510 may be bonded together with a bonding material 530.

[0031] The wiring pattern 280 is provided on the upper surface of the aluminum nitride substrate 201. The wiring pattern 280 is electrically connected to the laser chip 101 via a bonding wire 181. The wiring pattern 280 is also electrically connected to a wiring pattern 412 via a bonding wire 182.

[0032] The optical transceiver 1001 may include a coupler 521 for coupling an optical fiber that receives the optical transmission signal SLT (FIG. 1). The optical transceiver 1501 may also include a cylindrical magnet 522 around the coupler 521. The coupler 521 and the cylindrical magnet 522 may be attached to penetrate the wall portion 512.

[0033] FIG. 3 is a plan view schematically illustrating the laser chip 101 in an optical transceiver, the wiring pattern 280, the electronic components 102 and 103, and the thermistor 109 (temperature sensor) arranged around the laser chip 101. Note that the specific pattern shape of the wiring pattern 280 is omitted in FIG. 3 . The wiring pattern 280 may be designed according to the wiring to be realized. For example, the wiring pattern 280 may include a pattern shape that can electrically connect the bonding wire 181 and the bonding wire 182 with good characteristics. The wiring pattern 280 may also have pad shapes for mounting each of the multiple terminals of the electronic component 102 or the electronic component 103. The wiring pattern 280 may also have a pattern shape that is separated from the thermistor 109 to avoid electrical connection with the thermistor 109. The electronic components 102 and 103 are, for example, capacitors.

[0034] First Embodiment FIG. 4 is a cross-sectional view schematically showing the configuration of an optical transceiver 1501 according to a first embodiment.

[0035] The optical transceiver 1501 includes a laser chip 101, a lens 110, and at least one aluminum nitride substrate 200. In this specification, each aluminum nitride substrate has a single-layer structure. In other words, a given aluminum nitride substrate is composed of a single aluminum nitride member and does not include multiple aluminum nitride members bonded to each other via an adhesive other than aluminum nitride. In the first embodiment, the at least one aluminum nitride substrate 200 is a plurality of aluminum nitride substrates 200 including an aluminum nitride substrate 211 (a first aluminum nitride substrate in this embodiment) and an aluminum nitride substrate 212 (a second aluminum nitride substrate in this embodiment). The aluminum nitride substrate 211 has an upper surface (a first surface) on which the laser chip 101 is mounted and a lower surface (a second surface opposite the first surface). The upper surface of the aluminum nitride substrate 211 may be flat. Here, a flat surface refers to a surface on which no intentional irregularities are formed. Therefore, the flat surface may have minute irregularities on the order of the crystal grain size in the sintered member serving as the aluminum nitride substrate 211. The flat surface may also have a slight warp that occurs during the production of the sintered member serving as the aluminum nitride substrate 211.

[0036] In this embodiment 1 (Figure 4), a lens 110 is stacked on the upper surface of the aluminum nitride substrate 211 without being separated by any of the aluminum nitride substrates 200 of the optical transceiver 1501, and a laser chip 101 is mounted thereon.

[0037] The Peltier element PD has a pair of aluminum nitride substrates and a main body 301 supported therebetween. In this embodiment, the pair of aluminum nitride substrates are an aluminum nitride substrate 211 and an aluminum nitride substrate 212. The aluminum nitride substrate 212 is disposed away from the aluminum nitride substrate 211 in one direction (downward in FIG. 4 ) and faces the lower surface of the aluminum nitride substrate 211. The main body 301 is attached to the lower surface of the aluminum nitride substrate 211 to cool the laser chip 101. The main body 301 has a plurality of semiconductor members 30 and a plurality of metal members 35. The plurality of metal members 35 include at least one metal member (first metal member) disposed on one side (upper side in FIG. 4 ) in the thickness direction (vertical direction in FIG. 4 ) and at least one metal member (second metal member) disposed on the other side (lower side in FIG. 4 ) in the thickness direction. Each of the semiconductor members 30 is sandwiched between the metal members 35. Each of the first and second metal members is in contact with the semiconductor member 30. The first and second metal members sandwich the semiconductor member 30 in the thickness direction. The plurality of semiconductor members 30 include p-type semiconductor members 31 and n-type semiconductor members 32. The p-type semiconductor members 31 and the n-type semiconductor members 32 are alternately connected in series via metal members 35. The aluminum nitride substrate 212, together with the aluminum nitride substrate 211, sandwiches the main body portion 301. In other words, the main body portion 301 is disposed between the aluminum nitride substrate 211 and the aluminum nitride substrate 212.

[0038] The optical transceiver 1501 includes a heat sink 511. The heat sink 511 supports the aluminum nitride substrate 212 of the Peltier element PD and is made of metal. The aluminum nitride substrate 212 may be adhered to the heat sink 511 by an adhesive layer (not shown) made of a material other than aluminum nitride, such as a silicone adhesive sheet. The heat sink 511, together with a wall 512 and a lid 513, constitutes a housing 510 having a sealed internal space. The lens 110 is supported by the aluminum nitride substrate 211 directly or indirectly via a spacer (not shown). This spacer may be made of an inexpensive material other than aluminum nitride.

[0039] The wiring pattern 280 is provided directly on the upper surface of the aluminum nitride substrate 211. The wiring pattern 280 is electrically connected to the laser chip 101 via a bonding wire 181. The wiring pattern 280 is also electrically connected to the wiring pattern 412 via a bonding wire 182. The wiring pattern 280, electronic components 102 and 103, and thermistor 109 may also be provided on the aluminum nitride substrate 211, as shown in FIG.

[0040] Note that, other than the above, the configuration is almost the same as the configuration of the comparative example described above, so the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0041] According to the first embodiment, lens 110 is laminated on the upper surface of aluminum nitride substrate 211, and laser chip 101 is mounted thereon, without being separated by any of aluminum nitride substrates 200 included in optical transceiver 1501. This eliminates the need for an additional aluminum nitride substrate, such as aluminum nitride substrate 201 ( FIG. 2 : comparative example), on the upper surface of aluminum nitride substrate 211. This reduces the material cost for aluminum nitride substrate 200, and also reduces the thermal resistance between main body 301 of Peltier element PD and laser chip 101, thereby reducing the power consumption of Peltier element PD.

[0042] Second Embodiment FIG. 5 is a cross-sectional view schematically illustrating the configuration of an optical transceiver 1101 according to a second embodiment. In the second embodiment (FIG. 5), unlike the first embodiment (FIG. 4), all of the aluminum nitride substrates 200 included in the optical transceiver 1101 are positioned away from the lenses 110 in the planar layout. Therefore, the lenses 110 are positioned away from the aluminum nitride substrates 211 in the planar layout. As shown in FIG. 5, the lenses 110 may be positioned away from the Peltier element PD in the planar layout. The lenses 110 are positioned so that the laser light LL from the laser chip 101 passes through them, and also so as to intersect with an imaginary plane IP that includes the upper surface of the aluminum nitride substrate 211 of the Peltier element PD. The lenses 110 may be supported by a heat sink 511 directly or indirectly via a spacer (not shown). The spacer may be made of an inexpensive material other than aluminum nitride.

[0043] The configuration other than that described above is substantially the same as that of the first embodiment (FIG. 4) described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0044] According to the second embodiment, both the aluminum nitride substrate 200 (specifically, the aluminum nitride substrate 211 and the aluminum nitride substrate 212) are disposed away from the lens 110 in the planar layout. This allows the size of the aluminum nitride substrate 200 to be smaller than in the case of the first embodiment ( FIG. 4 ). This reduces the material cost for the aluminum nitride substrate 200. Furthermore, because the size of the aluminum nitride substrate 211 is small as described above, the size of the main body 301 for cooling it can also be reduced. This reduces the material cost for the main body 301. Furthermore, since it is no longer necessary to cool the lens 110, the power consumption of the Peltier element PD can be reduced by the amount. Specifically, by reducing the size of the Peltier element PD while maintaining the ability to cool the laser chip 101, the energy consumption associated with cooling can be reduced.

[0045] Furthermore, unlike optical transceiver 1001 (FIG. 2), optical transceiver 1101 (FIG. 5) of this second embodiment does not require aluminum nitride substrate 202 (FIG. 2) as a spacer for elevating laser chip 101 so that laser light LL from laser chip 101 passes through the appropriate position of lens 110. This is because, in this embodiment (FIG. 5), Peltier element PD functions not only as a cooler but also as a spacer. By omitting aluminum nitride substrate 202, the size of the optical transceiver can be reduced.

[0046] Third Embodiment FIG. 6 is a cross-sectional view schematically illustrating the configuration of an optical transceiver 1102 according to a third embodiment. Unlike the optical transceiver 1101 (FIG. 5: second embodiment), the optical transceiver 1102 (FIG. 6) does not have a wiring pattern 280 (FIG. 5) on the upper surface of the aluminum nitride substrate 211. In this third embodiment, the wiring pattern 412 of the wiring substrate 410 is electrically connected to the laser chip 101 by a bonding wire 183 without using the wiring pattern 280. In this third embodiment, the electronic components 102 and 103 (FIG. 3) may be mounted on the wiring substrate 410. The thermistor 109 (FIG. 3) may be provided on the aluminum nitride substrate 211.

[0047] The configuration other than that described above is substantially the same as that of the second embodiment (FIG. 5) described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0048] According to this embodiment, there is no need to provide wiring pattern 280 (FIG. 5: embodiment 2) on the upper surface of aluminum nitride substrate 211 (FIG. 6). As a result, the size of aluminum nitride substrate 211 can be reduced compared to embodiment 2 (FIG. 5). This reduces the material cost for aluminum nitride substrate 211. Furthermore, because the size of aluminum nitride substrate 211 is small as described above, the size of main body 301 for cooling it can also be reduced. This reduces the material cost for main body 301. Furthermore, because the size of main body 301 is small, the size of aluminum nitride substrate 212 supporting it can also be reduced. This reduces the material cost for aluminum nitride substrate 212 and the power consumption of Peltier element PD.

[0049] 7 is a cross-sectional view schematically illustrating the configuration of an optical transceiver 1201 according to a fourth embodiment. The optical transceiver 1201 includes at least one aluminum nitride substrate 200, which includes an aluminum nitride substrate 211 (a first aluminum nitride substrate in this embodiment), an aluminum nitride substrate 221 (a second aluminum nitride substrate in this embodiment), and an aluminum nitride substrate 222 (a third aluminum nitride substrate in this embodiment).

[0050] As with the optical transceiver 1101 (FIG. 5: embodiment 2), the optical transceiver 1201 (FIG. 7) also has a laser chip 101 mounted on the top surface of an aluminum nitride substrate 211. Furthermore, each of the aluminum nitride substrates 200 is positioned away from the lens 110 in the planar layout.

[0051] The optical transceiver 1201 (FIG. 7) has a support substrate 430 instead of the wiring substrate 410 (FIG. 5: embodiment 2). The support substrate 430 supports the aluminum nitride substrate 211. Therefore, the support substrate 430 supports the laser chip 101 via the aluminum nitride substrate 211. The support substrate 430 may be adhered to the aluminum nitride substrate 211 by an adhesive layer (not shown) made of a material other than aluminum nitride, and the adhesive layer may be, for example, a silicone adhesive sheet.

[0052] The support substrate 430 includes at least one metal via 432 and an insulator layer 431 in which the at least one metal via 432 is embedded. Specifically, the support substrate 430 has at least one through-hole, and the at least one metal via 432 completely fills the through-hole. The through-hole may penetrate the support substrate 430 in the thickness direction (the vertical direction in FIG. 7 ). In the example shown in FIG. 7 , the support substrate 430 has a single metal via 432. On the other hand, the aluminum nitride substrate 221 does not have a metal via. The insulator layer 431 may be made of an inexpensive material other than aluminum nitride, such as alumina. Alternatively, the insulator layer 431 may be an insulator layer included in a printed circuit board (PCB). In this case, the support substrate 430 can be manufactured using a known PCB manufacturing method. In the example shown in FIG. 7 , the at least one metal via 432 is a single metal via 432. Each metal via 432 has an upper end (first end) facing the aluminum nitride substrate 211 (upward in FIG. 7 ) and a lower end (second end opposite the first end). In the planar layout, the upper end of the metal via 432 at least partially overlaps the aluminum nitride substrate 211. In the example shown in FIG. 7 , the upper end of the metal via 432 is contained within the aluminum nitride substrate 211 in the planar layout. In the planar layout, the upper end of the metal via 432 may at least partially overlap the laser chip 101. A wiring pattern 433 is provided on the support substrate 430 to achieve the same function as the wiring pattern 412 ( FIG. 5 : Embodiment 2). The material of the metal via 432 is not particularly limited, but a material with high thermal conductivity is preferred so that the laser chip 101 can be effectively cooled by efficiently transferring heat. The thermal conductivity is preferably 100 W / m·K or more, and more preferably 200 W / m·K. Specifically, the material of the metal via 432 is, for example, a copper alloy such as copper molybdenum or copper tungsten, tungsten, or molybdenum. When such a material is used for the material of the metal via 432, the metal via 432 and the insulator layer 431 made of alumina can be formed by co-firing.Alternatively, the insulator layer 431 may be formed without the metal via 432, and then the metal via 432 may be formed using, for example, a plating method or a printing method. In this case, the material of the metal via 432 may be a material with a higher thermal conductivity, such as silver or copper.

[0053] The lens 110 may be supported directly by the support substrate 430 or indirectly via some spacer (not shown). The spacer may be made of a material different from that of the support substrate 430. The spacer may be made of an inexpensive material other than aluminum nitride.

[0054] The support substrate 430 has a surface within the sealed space that has a portion that directly or indirectly supports the lens 110 as described above and a portion that supports the laser chip 101 via the aluminum nitride substrate 211. These portions may be located at different positions in the thickness direction. This allows the relative positions of the lens 110 and the laser chip 101 in the thickness direction to be freely adjusted. To achieve this configuration, the insulator layer 431 of the support substrate 430 may have a stepped shape rather than a flat shape within the sealed space, as shown in FIG. 7 .

[0055] The optical transceiver 1201 (FIG. 7) has a housing 550 (FIG. 7) instead of the housing 510 (FIG. 5: embodiment 2). The housing 550 does not have the heat sink 511 (FIG. 5). The housing 550 is combined with the support substrate 430 to form a sealed internal space.

[0056] The optical transceiver 1201 has a Peltier element PD (cooler) connected to the lower end of the metal via 432. Specifically, the main body 301 is disposed between the aluminum nitride substrate 221 and the aluminum nitride substrate 222, and the lower end of the metal via 432 and the main body 301 are connected to each other via the aluminum nitride substrate 221. The aluminum nitride substrate 221 of the Peltier element PD may be adhered to a support substrate 430 having the metal via 432 by an adhesive layer (not shown). The adhesive layer is made of a material other than aluminum nitride, such as a silicone adhesive sheet.

[0057] The optical transceiver 1201 has a heat dissipation fin 380 connected to the Peltier element PD. Specifically, the heat dissipation fin 380 is connected to the main body 301 via an aluminum nitride substrate 222. The aluminum nitride substrate 222 may be adhered to the heat dissipation fin 380 with an adhesive layer (not shown). The adhesive layer is made of a material other than aluminum nitride, such as a silicone adhesive sheet. The material of the heat dissipation fin 380 preferably has high thermal conductivity, and is preferably aluminum, an aluminum alloy, copper, a copper alloy, or SUS.

[0058] As a modified example, the heat dissipation fins 380 may be omitted. Alternatively, the Peltier elements PD may be omitted instead of the heat dissipation fins 380, and the heat dissipation fins 380 may be connected to the lower ends of the metal vias 432 as a cooler without the Peltier elements PD being interposed therebetween.

[0059] The configuration other than that described above is substantially the same as that of the second embodiment (FIG. 5) described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0060] According to this embodiment, the laser chip 101 can be indirectly supported by using the support substrate 430 instead of the heat sink 511 (FIG. 5). By adjusting the shape of the insulator layer 431 of the support substrate 430, the relative positions of the lens 110 and the laser chip 101 in the thickness direction can be adjusted.

[0061] Furthermore, the Peltier element PD can be disposed outside the sealed space. This allows heat to be dissipated without the need for a heat sink 511 (FIG. 5: embodiment 2). Furthermore, by providing a large heat dissipation fin 380, for example, heat can be easily dissipated from the Peltier element PD. This reduces the power consumption of the Peltier element PD.

[0062] Fifth Embodiment Fig. 8 is a cross-sectional view showing a schematic configuration of an optical transceiver 1202 according to a fifth embodiment. Unlike the optical transceiver 1201 (Fig. 7: fourth embodiment), the optical transceiver 1202 (Fig. 8) has a Peltier element PE instead of the Peltier element PD (Fig. 7). Unlike the Peltier element PD, the Peltier element PE does not have the aluminum nitride substrate 221 (Fig. 7). Furthermore, a support substrate 440 is used instead of the support substrate 430 (Fig. 7).

[0063] The support substrate 440 has a wiring portion 441 connected to the metal via 432. The wiring portion 441 has an end portion exposed outside the sealed space, and in FIG. 8 has an end portion exposed on the lower surface of the insulator layer 431. The wiring portion 441 and the metal via 432 may be used as an electrical path for applying a current to the main body portion 304 of the Peltier element PE. The portion of the wiring portion 441 connected to the metal via 432 (the other end portion) may be sandwiched between the insulator layers 431 in the thickness direction, as shown in FIG. 7.

[0064] The main body 304 has at least one semiconductor member, all of which are p-type semiconductor members 31. In other words, all of the semiconductor members of the main body 304 have p-type conductivity. Therefore, none of the semiconductor members of the main body 304 include an n-type semiconductor member. As a modified example, an n-type semiconductor member may be used instead of the p-type semiconductor member 31. In other words, all of the semiconductor members of the main body 304 may have n-type conductivity. In that case, none of the semiconductor members of the main body 304 include a p-type semiconductor member.

[0065] The p-type semiconductor member 31 has a surface to be joined that is joined to a metal material, and in this embodiment, has a surface to be joined that is joined to a metal member 35. The surface to be joined is electrically connected to a metal via 432 via the metal member 35.

[0066] As a modified example, the p-type semiconductor member 31 may have a joining surface that is directly joined to the metal via 432 without going through the metal member 35. In this case, the joining surface is naturally electrically connected to the metal via 432.

[0067] The configuration other than that described above is substantially the same as that of the fourth embodiment (FIG. 7) described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0068] According to this embodiment, the aluminum nitride substrate 221 (FIG. 7: embodiment 4) is omitted, thereby making it possible to further reduce material costs.

[0069] Sixth Embodiment FIG. 9 is a cross-sectional view schematically showing the configuration of an optical transceiver 1301 according to a sixth embodiment.

[0070] The optical transceiver 1301 has a support substrate 450 instead of the support substrate 430 ( FIG. 7 , embodiment 4). The support substrate 450 has at least one metal via 452 instead of the at least one metal via 432 ( FIG. 7 , embodiment 4). Therefore, the support substrate 450 has at least one metal via 452 and an insulator layer 431 in which the at least one metal via 452 is embedded. Specifically, the support substrate 450 has at least one through-hole, and the at least one metal via 452 completely fills the through-hole. The through-hole may penetrate the support substrate 450 in the thickness direction (the vertical direction in FIG. 7 ).

[0071] Furthermore, unlike the optical transceiver 1201 (FIG. 7: fourth embodiment), the optical transceiver 1301 does not include the aluminum nitride substrate 211 (FIG. 7). The laser chip 101 is mounted on a support substrate 450. Therefore, unlike the support substrate 430 (FIG. 7: fourth embodiment), the support substrate 450 supports the laser chip 101 without the aluminum nitride substrate 211 (FIG. 7: fourth embodiment).

[0072] 9, the at least one metal via 452 is one metal via 452. The metal via 452 has an upper end (first end) facing toward the laser chip 101 (upward in FIG. 7) and a lower end (second end opposite the first end). In the planar layout, the upper end of the metal via 452 at least partially overlaps the laser chip 101. In the example shown in FIG. 9, the upper end of the metal via 452 is included in the laser chip 101 in the planar layout. The Peltier element PD is connected to the lower end of the metal via 452 instead of the lower end of the metal via 432 (FIG. 7: embodiment 4).

[0073] Note that, other than the above, the configuration is almost the same as the configuration of the fourth embodiment described above, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0074] According to this embodiment, the aluminum nitride substrate 211 (FIG. 7: embodiment 4) is not provided, which makes it possible to reduce material costs compared to the case of embodiment 4 (FIG. 7).

[0075] Furthermore, cooling is concentrated at the location on the support substrate 450 where the upper ends of the metal vias 452 are exposed. By mounting the laser chip 101 on this location, cooling efficiency is improved.

[0076] Seventh Embodiment FIG. 10 is a cross-sectional view schematically showing the configuration of an optical transceiver 1302 according to a seventh embodiment.

[0077] The optical transceiver 1302 has a support substrate 460 instead of the support substrate 440 ( FIG. 8 , embodiment 5). The support substrate 460 has at least one metal via 452 similar to that in embodiment 6 ( FIG. 9 ), instead of the at least one metal via 432 ( FIG. 8 , embodiment 5). Furthermore, the support substrate 460 has a wiring portion 441 similar to that in embodiment 6 ( FIG. 9 ). Therefore, the support substrate 460 has at least one metal via 452, an insulator layer 431 in which the at least one metal via 452 is embedded, and the wiring portion 441.

[0078] Furthermore, the optical transceiver 1302 differs from the optical transceiver 1202 (FIG. 8: embodiment 5) in that the aluminum nitride substrate 211 (FIG. 8) is omitted. The laser chip 101 is mounted on a support substrate 460. Therefore, unlike the support substrate 440 (FIG. 8: embodiment 5), the support substrate 460 supports the laser chip 101 without the aluminum nitride substrate 211 (FIG. 8: embodiment 5) interposed therebetween.

[0079] The configuration other than that described above is substantially the same as that of the fifth embodiment (FIG. 8) described above, and therefore the same or corresponding elements are given the same reference numerals and description thereof will not be repeated.

[0080] According to this embodiment, the aluminum nitride substrate 211 (FIG. 8: embodiment 5) is not provided, which makes it possible to reduce material costs compared to the case of embodiment 5 (FIG. 8).

[0081] Furthermore, cooling is concentrated at the location on the support substrate 460 where the upper ends of the metal vias 452 are exposed. By mounting the laser chip 101 on this location, cooling efficiency is improved.

[0082] <Simulation> The conditions and results of a simulation of the temperature distribution and heat flux of an optical transceiver in operation are described below. Note that the dimensions in the figures are in millimeters.

[0083] 11 and 12 are perspective and side views, respectively, showing the boundary conditions for simulation of a comparative example roughly corresponding to the optical transceiver 1001 (FIG. 2). The shape of the laser chip is a rectangular parallelepiped with a thickness of 0.175 mm, a width of 0.75 mm, and a length of 1.75 mm, which is the same for Examples A and B described below. The shape of each semiconductor member of the Peltier element is a cube with each side measuring 0.925 mm, which is the same for Examples A and B described below. In this comparative example, 16 semiconductor members arranged in a 4x4 pattern are used. In the figure, the heat dissipation from the bottom surface is 100 [W / m ２ ・K] is said to be

[0084] 13 and 14 are perspective and side views, respectively, showing the boundary conditions for simulation of Example A, which roughly corresponds to the optical transceiver 1101 (FIG. 5). In Example A and Example B described below, four semiconductor components arranged in a 2×2 pattern are used. In the figures, the heat dissipation from the bottom surface is 100 W / m ２ ・K] is said to be

[0085] 15 and 16 are perspective and side views, respectively, showing boundary conditions for a simulation of Example B, roughly corresponding to the optical transceiver 1201 ( FIG. 7 ). FIGS. 17 and 18 are cross-sectional views corresponding to the fields of view of FIGS. 15 and 16 . FIG. 19 is a partial perspective view showing the boundary conditions from a different angle than FIG. 15 . FIG. 20 is a perspective view showing heat dissipation locations under the boundary conditions with a sandy pattern. As shown in the cross-sectional views of FIGS. 17 and 18 , a metal via similar to metal via 432 in FIG. 7 is disposed below the laser chip, penetrating the PCB, which serves as an insulating layer. The metal via has a rectangular parallelepiped shape, with a height of 0.8 mm (vertical dimension in FIGS. 17 and 18 ), a length of 1.75 mm (horizontal dimension in FIG. 18 ), and a width of 0.75 mm (dimensions perpendicular to both the height and length directions). 19, the heat dissipation fins are made of aluminum alloy (6061 material). The width of each fin is 0.2 mm, the width of each gap between the fins is 0.2 mm, and the height of each fin is 1.0 mm. The heat dissipation rate from the heat dissipation point (sand pattern in FIG. 20) is 50 W / m ２ ・K] is said to be

[0086] The following Tables 1 and 2 show the physical property conditions for the simulation.

[0087]

[0088]

[0089] 21, 22, and 23 are cross-sectional views showing the simulation results of the temperature distributions of the comparative example, Example A, and Example B. Figures 24, 25, and 26 are cross-sectional views showing the simulation results of the heat flux distributions of the comparative example, Example A, and Example B. The cross-sectional views shown in Figures 21 to 23 are taken along cross sections where no metal vias appear, and the cross-sectional views in Figures 24 to 26 are taken along cross sections where metal vias appear.

[0090] With reference to the temperature distributions shown in Figures 21 to 23, the laser chip is cooled to approximately the same temperature in the comparative example (Figure 21), Example A (Figure 22), and Example B (Figure 23). Meanwhile, the Peltier element of the comparative example (see Figures 11 and 12) has 16 semiconductor members arranged in a 4x4 pattern, while the Peltier element of Example A (see Figures 13 and 14) and the Peltier element of Example B (see Figures 15 and 16) each have four semiconductor members arranged in a 2x2 pattern. Therefore, it can be seen that each of Examples A and B can reduce power consumption compared to the comparative example. In particular, in Example B (Figure 23), the lens (as well as the laser chip) is cooled to approximately the same temperature as the comparative example (Figure 21). This is thought to be because, unlike Example A, in Example B, the lens is separated from the main heat dissipation path from the laser chip to the Peltier element by a PCB (specifically, the insulator layer of the PCB; see insulator layer 431 in Figure 7) that has a relatively low thermal conductivity.

[0091] The above-described embodiments and modifications may be freely combined with each other. Although the present invention has been described in detail, the above description is illustrative in all respects and does not limit the present invention. It is understood that countless modifications not illustrated can be envisioned without departing from the scope of the present invention.

[0092] IP: Virtual plane PD, PE: Peltier element 30: Semiconductor member 31: p-type semiconductor member 32: n-type semiconductor member 35: Metal member 101: Laser chip 110: Lens 181-183: Bonding wire 200-203, 211, 212, 221, 222: Aluminum nitride substrate 280: Wiring pattern 301, 304: Main body 380: Heat dissipation fin 410: Wiring substrate 411, 431: Insulator layer 412, 433: Wiring pattern 430, 440, 450, 460: Support substrate 432, 452: Metal via 441: Wiring portion 1101, 1102, 1201, 1202, 1301, 1302, 1501: Optical transceiver

Claims

1. An optical transceiver for emitting output light in response to an input electrical signal, comprising a Peltier element, the Peltier element including: a first aluminum nitride substrate having a single-layer structure and having a first surface and a second surface opposite to the first surface; a second aluminum nitride substrate having a single-layer structure, disposed away from the first aluminum nitride substrate in one direction and facing the second surface; and a body supported between the first aluminum nitride substrate and the second aluminum nitride substrate, the body including: at least one semiconductor member; at least one first metal member in contact with the at least one semiconductor member; and at least one second metal member in contact with the at least one semiconductor member and sandwiching the at least one semiconductor member between the at least one first metal member, the optical transceiver further including: a laser chip for generating laser light mounted on the first surface of the first aluminum nitride substrate of the Peltier element; an optical transceiver comprising: a lens that is positioned away from the first aluminum nitride substrate in a planar layout perpendicular to the one direction, that is positioned so as to intersect with a virtual plane that includes the first surface of the first aluminum nitride substrate of the Peltier element, and that is positioned so that the laser light from the laser chip passes through; and a wiring pattern that is electrically connected to the laser chip and is provided directly on the first surface of the first aluminum nitride substrate.

2. An optical transceiver according to claim 1, wherein said first surface of said first aluminum nitride substrate is a flat surface.

3. An optical transceiver according to claim 1 or 2, further comprising a heat sink made of metal and supporting the second aluminum nitride substrate.

4. An optical transceiver for emitting output light in response to an input electrical signal, comprising: a laser chip for generating laser light; a lens disposed in a planar layout away from the laser chip and arranged so that the laser light from the laser chip passes through; and at least one aluminum nitride substrate, the at least one aluminum nitride substrate including a first aluminum nitride substrate having a first surface on which the laser chip is mounted and a second surface opposite to the first surface, each of the at least one aluminum nitride substrates being disposed away from the lens in the planar layout; the optical transceiver further comprises: a support substrate supporting the first aluminum nitride substrate, the support substrate including at least one metal via and an insulator layer in which the at least one metal via is embedded, the at least one metal via having a first end directed toward the first aluminum nitride substrate and a second end opposite to the first end, the first end of the at least one metal via at least partially overlapping the first aluminum nitride substrate in the planar layout; and the optical transceiver further comprises: an optical transceiver comprising: a cooler connected to the second end of the at least one metal via; and the first aluminum nitride substrate is free of metal vias.

5. An optical transceiver according to claim 4, wherein the cooler includes a Peltier element.

6. An optical transceiver as described in claim 5, wherein the Peltier element has at least one semiconductor member, and either each of the at least one semiconductor member has a p-type and the at least one semiconductor member does not include an n-type semiconductor member, or each of the at least one semiconductor member has an n-type and the at least one semiconductor member does not include a p-type semiconductor member, and the at least one semiconductor member has a joining surface joined to a metal material, and the joining surface is electrically connected to the at least one metal via.

7. An optical transceiver according to any one of claims 4 to 6, wherein the support substrate has at least one through hole, and the at least one metal via entirely fills the at least one through hole.

8. An optical transceiver according to any one of claims 4 to 6, wherein the lens is supported by the support substrate, and the insulating layer of the support substrate is made of alumina.

9. An optical transceiver for emitting output light in response to an input electrical signal, comprising: a laser chip for generating laser light; and a support substrate supporting the laser chip, wherein the support substrate includes at least one metal via and an insulator layer in which the at least one metal via is embedded, the at least one metal via having a first end directed toward the laser chip and a second end opposite to the first end, the optical transceiver further comprising: a cooler connected to the second end of the at least one metal via, the laser chip being mounted on the support substrate, and the first end of the at least one metal via at least partially overlapping the laser chip in a planar layout, the cooler including a Peltier element having at least one semiconductor member, each of the at least one semiconductor member having a p-type and the at least one semiconductor member not including an n-type semiconductor member, or each of the at least one semiconductor member having an n-type and the at least one semiconductor member not including a p-type semiconductor member, An optical transceiver, wherein the at least one semiconductor member has a surface to be bonded to a metal material, the surface to be bonded being electrically connected to the at least one metal via.

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