Optical semiconductor device

Abstract

A light semiconductor device (100) is provided with: a semiconductor laser (21) mounted on a bottom portion (103) of a package (110); a reception portion (10) that receives signal light (24) from the outside using local light source light (26) output from the laser (21); and a reception portion mounting substrate (30) on which the reception portion (10) including a semiconductor light receiving element (22) is mounted. The reception portion (10) is disposed on a side surface opposite the laser (21). The reception portion mounting substrate (30) is a non-transmissive substrate, and has a light passing portion (13) through which the local light source light (26) output from the laser (21) passes, and covers the bottom portion (103) surrounded by an outer peripheral portion (102) of the package (110).

Description

Technical Field

[0001] This application relates to optical semiconductor devices. Background Technology

[0002] Patent Document 1 discloses an optical module that multiplexes four optical signals of different wavelengths for transmission and reception. The optical module of Patent Document 1 is a transceiver integrated optical component that integrates a semiconductor laser and a semiconductor light-receiving element in a single package.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2016-197635 ( Figure 2 )

[0004] Optical semiconductor devices that integrate a semiconductor laser and a semiconductor light-receiving element into a single package typically place the semiconductor laser (transmitter side) and the semiconductor light-receiving element (receiver side) on the same substrate plane. Patent Document 1's transceiver-integrated optical assembly also places the semiconductor laser (transmitter side) and the semiconductor light-receiving element (receiver side) on the same substrate plane. Furthermore, Patent Document 1's transceiver-integrated optical assembly arranges the transmitter-side optical system and the receiver-side optical system without any optical obstructions such as walls. In cases where stray light leaks from the transmitter side to the receiver side, this stray light can become noise and degrade the characteristics of the receiver side.

[0005] In the transceiver integrated optical component of Patent Document 1, since the transmitting and receiving sides operate independently, stray light from the transmitting side can be separately packaged to prevent leakage to the receiving side, or a shielding wall can be provided even within the same package housing both sides. However, in optical semiconductor devices for digital coherent optical communication in recent years, it is necessary to transmit the light from the transmitting side (local oscillator light) to the receiving side during reception. When both a signal light source and a local oscillator light source are used, it is difficult to package the transmitting and receiving sides independently. Furthermore, when both the transmitting and receiving sides are configured in a single package, and both a signal light source and a local oscillator light source are used, it is difficult to provide space between the horizontally arranged transmitting and receiving sides to completely shield stray light due to the requirement for further miniaturization of the package size, making it difficult to configure the wall. Summary of the Invention

[0006] The purpose of the technology disclosed in this application is to prevent stray light from the transmitting side to the receiving side while achieving miniaturization, even in the case of digital coherent optical communication.

[0007] An example of an optical semiconductor device disclosed in this application is an optical semiconductor device that encapsulates a semiconductor laser that outputs laser light and a semiconductor light-receiving element that receives signal light from an external source, and performs digital coherent optical communication with the outside. The optical semiconductor device includes: a semiconductor laser mounted on the bottom of the package; a receiving section that uses laser light output from the semiconductor laser, i.e., local oscillator light, to receive signal light from an external source; and a receiving section mounting substrate on which the receiving section, including the semiconductor light-receiving element, is mounted. The receiving section is disposed on the side opposite to the surface facing the semiconductor laser. The receiving section mounting substrate is a non-transparent substrate through which laser light is impermeable, and has a light-transmitting section through which the local oscillator light output from the semiconductor laser passes, and covers the bottom surrounded by the outer periphery of the package in a state where there is no gap between it and the outer periphery of the package or a state where a gap exists. When the receiving section mounting substrate covers the bottom surrounded by the outer periphery of the package with a gap existing between it and the outer periphery, the length of the gap between the outer periphery of the package and the receiving section mounting substrate is less than or equal to the thickness of the receiving section mounting substrate.

[0008] An example of an optical semiconductor device disclosed in this application has a semiconductor laser that outputs laser light mounted on the bottom of a package. A receiver is mounted on the side opposite to the semiconductor laser in a receiver mounting substrate that covers the bottom of the package, which is surrounded by the outer periphery, with or without a gap between the receiver and the outer periphery. Therefore, even in the case of digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating the optical semiconductor device involved in Embodiment 1.

[0010] Figure 2 This is a diagram showing the bottom side of the package in the optical semiconductor device according to Embodiment 1.

[0011] Figure 3 It is along Figure 1 The cross-sectional view shown by the dashed line AA.

[0012] Figure 4 It is along Figure 1 The cross-sectional view shown by dashed lines in BB.

[0013] Figure 5 This indicates that a power supply is available. Figure 2 The diagram shows the substrate of the prism through which the transmitted light passes and the thermoelectric module.

[0014] Figure 6 It means Figure 1 The diagram shows the light transmission section of the substrate mounted on the receiving section.

[0015] Figure 7 This is an explanation Figure 1 A diagram of the gaps.

[0016] Figure 8 This is a diagram illustrating other examples of the encapsulation involved in Implementation 1.

[0017] Figure 9 This is a diagram showing the receiving path of the optical semiconductor device according to Embodiment 1.

[0018] Figure 10 This is a diagram showing the local oscillator light path of the optical semiconductor device according to Embodiment 1.

[0019] Figure 11 This is a diagram showing the transmission path of the optical semiconductor device according to Embodiment 1.

[0020] Figure 12 This is a diagram illustrating another example of the receiving section mounting substrate according to Embodiment 1.

[0021] Figure 13 This is a diagram illustrating another example of the receiving section mounting substrate according to Embodiment 1.

[0022] Figure 14 This is a diagram illustrating the optical semiconductor device involved in Embodiment 2.

[0023] Figure 15 This is a diagram illustrating the optical semiconductor device involved in Embodiment 3.

[0024] Figure 16 This is a diagram illustrating the optical semiconductor device involved in Embodiment 4.

[0025] Figure 17 This is a diagram showing the bottom side of the package in the optical semiconductor device according to Embodiment 4.

[0026] Figure 18 It is along Figure 16 The cross-sectional view shown by the dashed line AA.

[0027] Figure 19 It is along Figure 16 The cross-sectional view shown by dashed lines in BB.

[0028] Figure 20 It means Figure 17 The diagram shows an example of the connection between the grounding pattern and the substrate mounted on the receiving unit.

[0029] Figure 21 It means Figure 17 The diagram shows an example of the connection between the grounding pattern and the substrate mounted on the receiving unit.

[0030] Figure 22This is a diagram illustrating the optical semiconductor device involved in Embodiment 5.

[0031] Figure 23 It means Figure 22 The diagram shows the light transmission section of the substrate mounted on the receiving section.

[0032] Figure 24 It means Figure 23 A cross-sectional view of the light-transmitting part. Detailed Implementation

[0033] Implementation Method 1

[0034] Figure 1 This is a diagram illustrating the optical semiconductor device according to Embodiment 1. Figure 2 This is a diagram showing the bottom side of the package in the optical semiconductor device according to Embodiment 1. Figure 3 It is along Figure 1 The cross-sectional view shown by the dashed line AA, Figure 4 It is along Figure 1 The cross-sectional view shown by dashed lines in BB. Figure 5 This indicates that a power supply is available. Figure 2 The diagram shows the substrate of the prism through which the transmitted light passes and the thermoelectric module. Figure 6 It means Figure 1 The diagram shows the light transmission section of the substrate mounted on the receiving section. Figure 7 This is an explanation Figure 1 Diagram of the gap, Figure 8 This is a diagram illustrating other examples of the encapsulation involved in Implementation 1. Figure 9 This is a diagram showing the receiving path of the optical semiconductor device according to Embodiment 1. Figure 10 This is a diagram showing the local oscillator light path of the optical semiconductor device according to Embodiment 1. Figure 11 This is a diagram showing the transmission path of the optical semiconductor device according to Embodiment 1. Figure 12 as well as Figure 13This diagram illustrates another example of the receiving unit mounting substrate according to Embodiment 1. The optical semiconductor device 100 includes: a package 110; a receiver 51 for outputting transmitted light 25 to the outside; a receiver 52 for receiving signal light 24 from the outside; a window 62 for allowing the transmitted light 25 to pass from inside the package 110 to the receiver 51; a window 63 for allowing the received light 24 to pass from the receiver 52 to the inside of the package 110; a receiving unit 10 including a semiconductor light-receiving element 22; a receiving unit mounting substrate 30 on which the receiving unit 10 is mounted; and a transmitting unit 11 including a semiconductor laser 21 and mounted on the bottom 103 of the package 110. The transmitting unit 11 includes components for both transmitting and receiving signal light, but because it includes components for transmitting signal light, the components mounted on the bottom 103 of the package 110 are treated as a single transmitting unit. Furthermore, the receiving unit 10 only includes components for receiving signal light.

[0035] The optical semiconductor device 100 includes a semiconductor laser 21 that outputs laser light and a receiving unit 10 comprising a semiconductor light-receiving element 22 that receives signal light (i.e., receiver light 24) from the outside in a package 110, and performs digital coherent optical communication with the outside. In receiving the receiver light 24, the digital coherent optical communication uses the laser light output from the semiconductor laser 21, i.e., the local oscillator light 26, to receive the receiver light 24. In this specification, an example is provided that uses both a signal light source (outputting signal light 25 to be transmitted externally) and a local oscillator light source (outputting the laser light used in receiving the receiver light 24).

[0036] The receiving unit 10 includes, for example, a prism 53, a polarization combining and splitting prism 54, a polarization rotating plate 55, a prism 56, three lenses 57, 58, and 59, a 90-degree mixer 91, a lens 60, a semiconductor light-receiving element 22, and an amplifier 92. The transmitting unit 11 includes, for example, three thermoelectric modules 71, 72, and 76, substrates 68, 65, and 77 disposed on each thermoelectric module 71, 72, and 76, a semiconductor laser 21 disposed on substrate 77, a lens 69, a prism 67 disposed on substrate 65, a polarization rotating plate 66, a polarization combining and splitting prism 64, and two prisms 14 and 15 disposed on substrate 68. The receiving unit is mounted on a substrate 30, which is a non-transparent substrate 37 that does not transmit laser light. The non-transparent substrate 37 is made of a light-transmitting material, such as metal or ceramic. The receiving unit mounting substrate 30 has a through-hole 12 for the transmission of the received light 24 and a through-hole 13 for the transmission of the laser light output from the semiconductor laser 21, i.e., the local oscillator light 26. Holes 12 and 13 penetrate the surface of the receiving unit mounting substrate 30 opposite to the semiconductor laser 21 and the surface opposite to that surface. Appropriately, the surface of the receiving unit mounting substrate 30 opposite to the semiconductor laser 21 is represented as the inner surface of the receiving unit mounting substrate 30, and the surface opposite to the semiconductor laser 21 is represented as the outer surface of the receiving unit mounting substrate 30. When the material of the non-transparent substrate 37, i.e., the substrate base, is metal, the receiving unit mounting substrate 30 is a metal substrate. When the material of the non-transparent substrate 37, i.e., the substrate base, is ceramic, the receiving unit mounting substrate 30 is a ceramic substrate.

[0037] Package 110 includes: an outer peripheral portion 102, a bottom portion 103, a substrate placement portion 104 extending inward from the outer peripheral portion 102 and arranging a receiving portion mounting substrate 30 thereon, a substrate connection pattern 105 of metal formed on the substrate placement portion 104 and connected to the receiving portion mounting substrate 30 via a conductive connection member 35, and an electrode pattern 106 electrically connected to the outside. The substrate placement portion 104 is formed at a position closer to the bottom 103 than the end of the outer peripheral portion furthest from the bottom 103 in the vertical direction, and extends inward from the outer peripheral portion 102 in a horizontal direction perpendicular to the vertical direction of the bottom 103. The substrate placement portion 104 can also be referred to as part of the outer peripheral portion 102. Semiconductor elements, thermoelectric modules, etc., within package 110 are connected to external devices via the electrode pattern 106. The receiving portion mounting substrate 30 covers the bottom 103 of package 110 and covers the transmitting portion 11, which includes a semiconductor laser 21, mounted on the bottom 103 of package 110. The optical semiconductor device 100 of Embodiment 1 has a three-dimensional configuration as described below: a transmitting section 11 including a semiconductor laser 21 that outputs laser light and a receiving section 10 including a semiconductor light-receiving element 22 that receives signal light, i.e., receiving light 24, from the outside are sandwiched between a receiving section mounting substrate 30. The optical semiconductor device 100 of Embodiment 1 can expand the mounting area inside the package 110 through its three-dimensional configuration. That is, the optical semiconductor device 100 of Embodiment 1 can shorten its length in the direction perpendicular to the travel direction of the receiving light 24 and the transmitting light 25, thus achieving miniaturization. Furthermore, after mounting the transmitting section 11 and the receiving section 10 mounted on the receiving section mounting substrate 30, a cover (not shown) is connected to a surface approximately parallel to the bottom 103 on the side of the outer periphery 102 that is not connected to the bottom 103, and the interior is sealed by the cover. Here, "approximately parallel" is not limited to perfect parallelism, but also includes permissible angular deviations.

[0038] Prisms 14, 15, 53, 56, and 67 are components that change the direction of travel of laser light. Polarization combining and splitting prisms 54 and 64 are prisms that combine or split X-polarized and Y-polarized light. Polarization rotating plates 55 and 66 are plate-shaped components that change the direction of polarization. Lenses 57, 58, 59, 60, and 69 are components that reduce the beam diameter of laser light. Windows 62 and 63 are glass components that allow signal light to pass through. Substrates 65, 68, and 77 are plate-shaped components that adjust the height of the mounted components. Thermoelectric modules 71, 72, and 76 are temperature adjustment components, such as Peltier elements. Thermoelectric modules 71, 72, and 76 stabilize the frequency of the laser output from the semiconductor laser 21 mounted on substrates 68, 65, and 77, as well as the characteristics of prisms 67, 14, and 15, and other components.

[0039] The 90-degree mixer 91 is a component used to combine signal light and local oscillator light (reference wave) to obtain light output corresponding to polarization. For example, when the signal light modulation method is QPSK (Quadrature Phase Shift Keying), the 90-degree mixer 91 outputs four signal lights. The semiconductor light-receiving element 22 has four light-receiving sections 23 that respectively receive the four signal lights output from the 90-degree mixer 91. The semiconductor light-receiving element 22 is, for example, a waveguide-type photodiode. The amplifier 92 amplifies the four signals output by the semiconductor light-receiving element 22.

[0040] Sockets 51 and 52 are located on the same side of the outer perimeter 102. Figure 3 In the diagram, the substrate placement section 104 is located on the outer periphery 102 opposite to the sockets 51 and 52, between dashed lines 81a and 81b. Furthermore, a substrate placement section 104 is also formed on the inner side of the outer periphery 102 in a direction perpendicular to the travel direction of the receiving light 24 and the transmitting light 25; a cross-section of this portion is shown below. Figure 4 Appropriately, the sides of sockets 51 and 52 are shown as the front side, and the side opposite to sockets 51 and 52 is shown as the rear side. Additionally, appropriately, Figure 1 , Figure 2 The orientation is shown as frontal. Figure 3 In the image, electrode pattern 106 is omitted, and holes 12 and 13 are represented by blank spaces. Figure 3 , Figure 4 The image shows an example where the bottom 103 of the package 110 is substantially parallel to the receiving portion mounting substrate 30.

[0041] exist Figure 6 The main part of the front of the receiving unit mounting substrate 30 is shown, which includes two light-passing portions, namely holes 12 and 13. Figure 6 The left side is the front side of the optical semiconductor device 100. Figure 6 The right side is the rear side of the optical semiconductor device 100. Prism 53 is configured to cover hole 12, and prism 56 is configured to cover hole 13. Prism 14 is configured on substrate 68 such that it includes the central axis 41 of the light-passing portion in front of hole 12. Prism 15 is configured on substrate 68 such that it includes the central axis 42 of the light-passing portion in rear of hole 13. Prisms 53 and 14 are configured to include central axis 41. Similarly, prisms 56 and 15 are configured to include central axis 42.

[0042] Figure 1 An example is shown in which there is a gap 43 between the receiving portion mounting substrate 30 and the outer periphery 102 of the package 110. Figure 1The illustrated optical semiconductor device 100 is an example in which the receiving unit mounting substrate 30 covers most of the bottom 103 surrounded by the outer periphery 102 of the package 110, that is, the bottom 103 surrounded by the outer periphery 102 of the package 110 is covered in a state where a gap 43 exists between the receiving unit 11 and the outer periphery 102, i.e., a gap 43 that connects the transmitting unit 11 and the receiving unit 10. Even in this case, as Figure 7 As shown, the length of the gap 43 between the outer periphery 102 of the package 110 and the receiving substrate 30, i.e., the gap length d, can be less than or equal to the thickness of the receiving substrate 30, i.e., the substrate thickness h. The dashed line 82a indicates the position of the inner surface of the outer periphery 102 of the package 110, and the dashed line 82b indicates the position of the side of the receiving substrate 30 opposite to the outer periphery 102 of the package 110. In the outer periphery 102 where the substrate placement section 104 is provided, there is no gap 43 connecting the transmitting section 11 and the receiving section 10. If the gap length d of the gap 43 is less than or equal to the substrate thickness h, even if the laser output from the semiconductor laser 21 deviates from the optical path during reception and transmission due to the components mounted on the bottom 103 of the package 110, resulting in stray light, the stray light will disappear and not reach the receiving side because no component is used to allow the stray light to travel directly to the gap 43. Therefore, when the receiving portion mounting substrate 30 covers most of the bottom 103 surrounded by the outer periphery 102 of the package 110, the length (gap length d) of the gap 43 between the outer periphery 102 of the package 110 and the receiving portion mounting substrate 30 can be less than or equal to the thickness (substrate thickness h) of the receiving portion mounting substrate 30.

[0043] Figure 8 The other package 110 shown is an example in which a substrate mounting portion 104 is provided on the inner side of the outer periphery 102 of the package 110 where windows 62, 63 are not configured. It possesses... Figure 8 The other optical semiconductor device 100 shown in the package 110 is an example in which the receiving portion mounting substrate 30 covers the entire bottom 103 surrounded by the outer periphery 102 of the package 110, that is, the bottom 103 surrounded by the outer periphery 102 of the package 110 is covered in a state in which there is no gap 43 between the package 110 and the outer periphery 102, that is, there is no gap 43 connecting the transmitting portion 11 and the receiving portion 10. In this case, since there is no gap 43 between the outer periphery 102 of the package 110 and the receiving portion mounting substrate 30, the degree of freedom in the arrangement of components mounted on the bottom 103 of the package 110 can be improved.

[0044] use Figures 9-11 The optical path during reception and the optical path during transmission are described. Figure 9 The receiving path of the receiving unit 10 is shown. Furthermore, in Figure 9In the diagram, dashed lines represent prisms 14 and 15 mounted on the bottom 103 of package 110, and dashed lines also represent windows 63 opposite to prisms 14 and 15. Figure 10 The receiving path of the receiving light 24 in the transmitting section 11 mounted on the bottom 103 of the package 110 and the light path of the local oscillator light 26 used during reception are shown. Furthermore, in Figure 10 In the diagram, prisms 53 and 56, mounted on the receiving unit mounting substrate 30, are indicated by dashed lines. Figure 11 The transmission path of the transmitting unit 11 mounted on the bottom 103 of the package 110 is shown.

[0045] The received light 24, following optical path s1, enters the prism 14 through window 63. Following optical path s2, the received light 24 is reflected by prism 14 towards the aperture 12 side of the receiving unit mounting substrate 30, and then enters the prism 53 through the aperture 12. Subsequently, a portion of the received light 24, such as X-polarized signal light, enters the lens 59 through polarization combining and dividing waveguide prism 54, following optical path s3. A portion of the received light 24, such as Y-polarized signal light, is separated by polarization combining and dividing waveguide prism 54, following optical path s4, and enters the lens 57 through polarization rotating plate 55.

[0046] The local oscillator light 26, which is the laser emitted from the semiconductor laser 21, is incident on the prism 67 through the lens 69, following optical path a1. The local oscillator light 26 is reflected by the prism 67 and incident on the prism 15, following optical path a2. The local oscillator light 26 is reflected by the prism 15 towards the aperture 13 side of the receiving unit mounting substrate 30, following optical path a3, and incident on the prism 56 through the aperture 13. Subsequently, the local oscillator light 26 is incident on the lens 58, following optical path a4. The X-polarized signal light of the received light 24 is incident on the 90-degree mixer 91 from the lens 59, following optical path s6. The Y-polarized signal light of the received light 24 is incident on the 90-degree mixer 91 from the lens 57, following optical path s5. The local oscillator light 26 is incident on the 90-degree mixer 91 from the lens 58, following optical path a5.

[0047] The 90-degree mixer 91, based on the X-polarized signal light from the received light 24 and the local oscillator light 26, outputs the in-phase signal light XI and the orthogonal signal light XQ from the X-polarized light of the received light 24. The in-phase and orthogonal signal lights XI and XQ from the X-polarized light 24 are incident on the two light-receiving sections 23 of the semiconductor light-receiving element 22 through the lens 60, as follows, along optical paths s10 and s9, respectively. Furthermore, the 90-degree mixer 91, based on the Y-polarized signal light from the received light 24 and the local oscillator light 26, outputs the in-phase and orthogonal signal lights YI and YQ from the Y-polarized light of the received light 24. The in-phase and orthogonal signal lights YI and YQ from the Y-polarized light 24 are incident on the two light-receiving sections 23 of the semiconductor light-receiving element 22 through the lens 60, as follows, along optical paths s8 and s7, respectively. Figure 9 The four light-receiving units 23 shown are, from right to left, designated as the first light-receiving unit, the second light-receiving unit, the third light-receiving unit, and the fourth light-receiving unit. The first light-receiving unit 23 receives the signal light XI from the received light 24, the second light-receiving unit 23 receives the signal light XQ from the received light 24, the third light-receiving unit 23 receives the signal light YI from the received light 24, and the fourth light-receiving unit 23 receives the signal light YQ from the received light 24.

[0048] When the optical semiconductor device 100 outputs transmitted light 25, the semiconductor laser 21 outputs signal light as pre-modulated laser light. The pre-modulated signal light output from the semiconductor laser 21, following optical path t1, is incident on the laser processor 95 through lens 69. The laser processor 95, for example, in the case where the signal light modulation method is QPSK, outputs X-polarized signal light TX and Y-polarized signal light TY modulated based on four modulation signals TXI, TXQ, TYI, and TYQ. The X-polarized signal light TX is incident on the polarization combining and splitting prism 64, following optical path t2. The Y-polarized signal light TY, following optical path t3, is incident on the polarization combining and splitting prism 64 through polarization rotation plate 66. Following optical path t4, the transmitted light 25, after combining the signal light TX and signal light TY through the polarization combining and splitting prism 64, is output to the outside through window 62 from socket 51. The X-polarized signal light TX and Y-polarized signal light TY are combined by the polarization combining and splitting prism 64.

[0049] In addition, Figure 1 , Figure 3 , Figure 10 In this diagram, the laser processor 95, which outputs the combined signal light 25 as the transmit light, is omitted. The laser processor 95 may, for example, include a waveguide through which the local oscillator light 26 passes. In this case, the local oscillator light 26, after passing through the waveguide of the laser processor 95, is incident on the prism 67.

[0050] Even if the laser light output from the semiconductor laser is reflected by the components of the transmitting unit 11, resulting in stray light that follows a different path than the light paths a1, a2, a3, t1, t2, t3, the receiving unit mounting substrate 30 will act as a physical barrier. Therefore, the optical semiconductor device 100 of Embodiment 1 reflects the stray light through the receiving unit mounting substrate 30, thereby preventing the stray light from leaking into the receiving unit 10, which is positioned on the opposite side of the transmitting unit 11 and sandwiches the receiving unit mounting substrate 30, thus preventing the deterioration of the optical characteristics of the received light 24.

[0051] As described above, the transceiver integrated optical assembly of Patent Document 1 mounts a semiconductor laser (transmitter side) and a semiconductor light-receiving element (receiver side) on the same plane of the same substrate. Therefore, electrical noise leaking from high-frequency signals such as modulation signals from the transmitter side reaches the receiver side, potentially causing performance degradation. In contrast, the optical semiconductor device 100 of Embodiment 1, with its transmitter 11 (including a semiconductor laser 21) and receiver 10 (including a semiconductor light-receiving element 22) sandwiched by a receiver mounting substrate 30, prevents electrical noise from the transmitter 11 side from leaking to the receiver 10 side via the receiver mounting substrate 30. When the receiver mounting substrate 30 is a metal substrate, the effect of preventing electrical noise leakage to the receiver 10 side is improved compared to when the receiver mounting substrate 30 is a ceramic substrate. Furthermore, since the semiconductor light-receiving element 22 and amplifier 92 are formed on an insulating substrate, they can operate even when mounted on a receiver mounting substrate 30, which is a metal substrate. Furthermore, in the absence of semiconductor light-receiving element 22 and amplifier 92 being formed on an insulating substrate, an insulating substrate such as aluminum oxide or aluminum nitride is sandwiched between the receiving portion mounting substrate 30, which is a metal substrate.

[0052] In the transceiver integrated optical assembly of Patent Document 1, when a wall is arranged between the transmitting side and the receiving side, a gap needs to be provided between the cover and the wall to prevent interference between the package and the cover that closes the package. Since the gap generated between the cover and the wall becomes longer in the long side direction of the package, i.e., in the direction parallel to the transmitted light and the received light, it becomes a structure in which stray light can easily leak from the gap between the transmitting side and the receiving side, which are arranged in a horizontal direction perpendicular to the long side direction. In contrast, the optical semiconductor device 100 of Embodiment 1 is arranged with the transmitting section 11 including the semiconductor laser 21 and the receiving section 10 including the semiconductor light-receiving element 22 sandwiching the receiving section mounting substrate 30, so it can prevent stray light from the transmitting side to the receiving side. In the optical semiconductor device 100 of Embodiment 1, even if there is a small gap 43 between the receiving section mounting substrate 30 and the outer periphery 102 of the package 110, since no component is used to allow stray light to travel directly between the receiving section mounting substrate 30 and the outer periphery 102 of the package 110, even if stray light is generated, it will disappear and not reach the receiving side.

[0053] In the receiving section mounting substrate 30, the surface opposite to the semiconductor laser 21 is not limited to a plane, such as... Figure 12 , Figure 13 In this way, a plurality of recesses 38 can be provided on the surface opposite to the semiconductor laser 21. Protrusions 39 are formed between adjacent recesses 38. Figure 12 The recess 38 shown is an example of uneven depth and shape. Figure 13 The recess 38 shown is an example of uniform depth and shape. When stray light 34a is incident on the recess 38 of the receiving unit mounting substrate 30, it undergoes multiple reflections within the recess 38, and the attenuated stray light 34b is emitted from the recess 38 of the receiving unit mounting substrate 30 toward the bottom 103 side of the package 110. The deeper the recess 38, the more times multiple reflections occur within the recess 38, thus the effect of stray light attenuation is high when the recess 38 is deep. The recess 38 formed on the receiving unit mounting substrate 30 can attenuate light with the same frequency as the local oscillator light 26 through multiple reflections. Therefore, the optical semiconductor device 100 of Embodiment 1, which has a receiving unit mounting substrate 30 with multiple recesses 38 formed on the surface opposite to the semiconductor laser 21, can improve the effect of preventing stray light from the transmitting side to the receiving side compared to the optical semiconductor device 100 of Embodiment 1, which has a receiving unit mounting substrate 30 with no recesses 38 formed on the surface opposite to the semiconductor laser 21.

[0054] As described above, the optical semiconductor device 100 of Embodiment 1 is an optical semiconductor device that houses a semiconductor laser 21 that outputs laser light and a semiconductor light-receiving element 22 that receives signal light (receiving light 24) from the outside in a package 110, and performs digital coherent optical communication with the outside. The optical semiconductor device 100 of Embodiment 1 includes: a semiconductor laser 21 mounted on the bottom 103 of the package 110; a receiving unit 10 that uses a local oscillator light source 26, which is the laser light output from the semiconductor laser 21, to receive signal light (receiving light 24) from the outside; and a receiving unit mounting substrate 30 on which the receiving unit 10, including the semiconductor light-receiving element 22, is mounted. The receiving unit 10 is disposed on the side opposite to the side facing the semiconductor laser 21. The receiving unit mounting substrate 30 is a non-transparent substrate 37 that does not transmit laser light, and has a light-transmitting portion (hole 13) through which the local oscillator light 26 output from the semiconductor laser 21 passes. It covers the bottom 103 surrounded by the outer periphery 102 of the package 110 in a state where there is no gap 43 between the receiving unit mounting substrate 30 and the outer periphery 102, or where there is a gap 43. When the receiving unit mounting substrate 30 covers the bottom 103 surrounded by the outer periphery 102 of the package 110 with a gap 43 present, the length of the gap 43 between the outer periphery 102 of the package 110 and the receiving unit mounting substrate 30 (gap length d) is less than or equal to the thickness of the receiving unit mounting substrate 30 (substrate thickness h). According to the structure of the optical semiconductor device 100 of Embodiment 1, a semiconductor laser 21 that outputs laser light is mounted on the bottom 103 of the package 110, and a receiver 10 is mounted on the side opposite to the semiconductor laser 21 of the receiver mounting substrate 30 that covers the bottom 103 surrounded by the outer peripheral portion 102 of the package 110, in a state where there is no gap 43 between the receiver and the outer peripheral portion 102 or there is a gap 43. Therefore, even when performing digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization.

[0055] Implementation Method 2

[0056] Figure 14 This is a diagram illustrating the optical semiconductor device involved in Embodiment 2. Figure 14 The sectional view shown is consistent with that of Embodiment 1. Figure 3 The corresponding figure. The difference between the optical semiconductor device 100 of Embodiment 2 and the optical semiconductor device 100 of Embodiment 1 is that a metal plating layer 31 is formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21 and on the surface opposite to that surface. The main difference from the optical semiconductor device 100 of Embodiment 1 will be explained.

[0057] The receiving unit mounting substrate 30 in Embodiment 2 includes a non-transparent substrate 37 and a metal plating layer 31 formed on the inner and outer surfaces of the non-transparent substrate 37. The metal plating layer 31 has openings 33 at the portions of holes 12 and 13. The non-transparent substrate 37 is made of a light-impermeable material, such as metal or ceramic. Received light 24 is input from the transmitting unit 11 to the receiving unit 10 through the openings 33 and holes 12 on the inner surface of the receiving unit mounting substrate 30 and the openings 33 on the outer surface of the receiving unit mounting substrate 30. Local oscillator light 26 is input from the transmitting unit 11 to the receiving unit 10 through the openings 33 and holes 13 on the inner surface of the receiving unit mounting substrate 30 and the openings 33 on the outer surface of the receiving unit mounting substrate 30. Furthermore, in Figure 14 In the diagram, electrode pattern 106 is omitted, and holes 12, 13, and opening 33 are indicated by blanks. In Embodiment 2, the optical semiconductor device 100 has a metal plating layer 31 formed on the surface of the receiving section mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface. Therefore, compared to a ceramic substrate, the receiving section mounting substrate 30 can improve the effect of preventing electrical noise from the transmitting section 11 side to the receiving section 10 side.

[0058] The optical semiconductor device 100 of Embodiment 2 has the same structure as the optical semiconductor device 100 of Embodiment 1, except that a metal plating layer 31 is formed on the surface of the receiving section mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface. Therefore, similar to the optical semiconductor device 100 of Embodiment 1, even when performing digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization. Like the optical semiconductor device 100 of Embodiment 1, the optical semiconductor device 100 of Embodiment 2 reflects stray light through the receiving section mounting substrate 30, thereby preventing stray light from leaking into the receiving section 10, which is disposed on the opposite side of the transmitting section 11 and sandwiching the receiving section mounting substrate 30, and thus preventing the degradation of the optical characteristics of the received light 24.

[0059] exist Figure 14 The example shown illustrates a metal plating layer 31 formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface. However, it is sufficient to form the metal plating layer 31 on at least the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21. The optical semiconductor device 100 of Embodiment 2, which has a receiving portion mounting substrate 30 with a metal plating layer 31 formed on its inner surface (the surface opposite to the semiconductor laser 21), also achieves the same effect as the optical semiconductor device 100 of Embodiment 2, which has a receiving portion mounting substrate 30 with metal plating layers 31 formed on both its inner and outer surfaces.

[0060] Implementation Method 3

[0061] Figure 15This is a diagram illustrating the optical semiconductor device involved in Embodiment 3. Figure 15 The sectional view shown is consistent with that of Embodiment 1. Figure 3 The corresponding figure. The difference between the optical semiconductor device 100 of Embodiment 3 and the optical semiconductor device 100 of Embodiment 1 is that a black plating layer 32 is formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21 and on the surface opposite to that surface. The main difference from the optical semiconductor device 100 of Embodiment 1 will be explained.

[0062] The receiving unit mounting substrate 30 in Embodiment 3 includes a non-transparent substrate 37 and a black plating layer 32 formed on the inner and outer surfaces of the non-transparent substrate 37. The black plating layer 32 is, for example, a nickel (Ni) or chromium (Cr) plating layer. The black plating layer 32 has openings 33 at the portions of holes 12 and 13. The non-transparent substrate 37 is made of a light-impermeable material, such as metal or ceramic. The received light 24 is input from the transmitting unit 11 to the receiving unit 10 through the openings 33 and holes 12 on the inner surface of the receiving unit mounting substrate 30 and the openings 33 on the outer surface of the receiving unit mounting substrate 30. The local oscillator light 26 is input from the transmitting unit 11 to the receiving unit 10 through the openings 33 and holes 13 on the inner surface of the receiving unit mounting substrate 30 and the openings 33 on the outer surface of the receiving unit mounting substrate 30. Furthermore, in Figure 15 In the diagram, electrode pattern 106 is omitted, and holes 12, 13, and opening 33 are indicated by blanks. The black plating layer 32 absorbs the laser emitted by the semiconductor laser 21. Therefore, even in the event of stray light, the black plating layer 32 of the receiving section mounting substrate 30 can absorb the stray light, thus preventing stray light from the transmitting side to the receiving side. In Embodiment 3, the optical semiconductor device 100 has a black plating layer 32 formed on the surface of the receiving section mounting substrate 30 opposite to the semiconductor laser 21 and on the surface opposite to that surface. Therefore, compared to the receiving section mounting substrate 30, which is a ceramic substrate, it can improve the effect of preventing electrical noise from the transmitting section 11 side to the receiving section 10 side.

[0063] The optical semiconductor device 100 of Embodiment 3 has the same structure as the optical semiconductor device 100 of Embodiment 1, except that a black plating layer 32 is formed on the surface of the receiving section mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface. Therefore, similar to the optical semiconductor device 100 of Embodiment 1, even when performing digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization. Since the black plating layer 32 of the receiving section mounting substrate 30 of Embodiment 3 absorbs stray light, similar to the optical semiconductor device 100 of Embodiment 1, stray light will not leak to the receiving section 10, which is disposed on the opposite side of the transmitting section 11 and sandwiches the receiving section mounting substrate 30, thus preventing the degradation of the optical characteristics of the received light 24.

[0064] exist Figure 15 The example shown illustrates a black plating layer 32 formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side thereof. However, it is sufficient that at least the black plating layer 32 is formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21. The optical semiconductor device 100 of Embodiment 3, which has a receiving portion mounting substrate 30 having a black plating layer 32 formed on its inner surface (the surface opposite to the semiconductor laser 21), also achieves the same effect as the optical semiconductor device 100 of Embodiment 3, which has a receiving portion mounting substrate 30 having black plating layers 32 formed on both its inner and outer surfaces.

[0065] Implementation Method 4

[0066] Figure 16 This is a diagram illustrating the optical semiconductor device according to Embodiment 4. Figure 17 This is a diagram showing the bottom side of the package in the optical semiconductor device according to Embodiment 4. Figure 18 It is along Figure 16 The cross-sectional view shown by the dashed line AA, Figure 19 It is along Figure 16 The cross-sectional view shown by dashed lines in BB. Figure 20 , Figure 21 They represent Figure 17 The diagram shows an example of the connection between the grounding pattern and the substrate mounted on the receiving section. Furthermore, in... Figure 18 In the diagram, electrode pattern 106 is omitted, and holes 12 and 13 are indicated with blanks. The difference between the optical semiconductor device 100 of Embodiment 4 and the optical semiconductor devices 100 of Embodiments 1-3 is that the substrate mounting portion 104 of the package 110 has a grounding pattern 108 of metal that becomes the ground potential of the optical semiconductor device, and the receiving portion mounting substrate 30 is connected to the grounding pattern 108 via a conductive connection member 35. The differences from the optical semiconductor device 100 of Embodiment 1 will be mainly described.

[0067] In the optical semiconductor device 100 of Embodiment 4, it can also be said that the metal substrate connection pattern 105 in the optical semiconductor device 100 of Embodiment 1 becomes the ground potential of the optical semiconductor device. Since the receiving section mounting substrate 30 of the optical semiconductor device 100 of Embodiment 4 becomes the ground potential of the optical semiconductor device, the effect of preventing electrical noise from the transmitting section 11 side to the receiving section 10 side can be improved compared with the optical semiconductor device 100 of Embodiment 1.

[0068] The conductive connection component 35 is, for example, solder or conductive adhesive. An example of the connection between the ground pattern 108 of the package 110 and the receiving unit mounting substrate 30 when the conductive connection component 35 is solder 16 is shown below. Figure 20An example of the connection between the grounding pattern 108 of the package 110 and the receiving unit mounting substrate 30 when the conductive connecting member 35 is a conductive adhesive 17 is shown below. Figure 21 Furthermore, the conductive connection component 35 in the optical semiconductor device 100 of embodiments 1 to 3 may also be, for example, solder or conductive adhesive.

[0069] The optical semiconductor device 100 of Embodiment 4 has the same structure as the optical semiconductor device 100 of Embodiment 1, except that the receiving unit mounting substrate 30 is connected to the ground pattern 108 of the package 110 via the conductive connection member 35. Therefore, similar to the optical semiconductor device 100 of Embodiment 1, even in the case of digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization. Like the optical semiconductor device 100 of Embodiment 1, the optical semiconductor device 100 of Embodiment 4 reflects stray light through the receiving unit mounting substrate 30, thereby preventing stray light from leaking to the receiving unit 10, which is disposed on the opposite side of the transmitting unit 11 with the receiving unit mounting substrate 30 sandwiched between it, and preventing the degradation of the optical characteristics of the received light 24.

[0070] Furthermore, the optical semiconductor device 100 of Embodiment 4, which includes the receiving portion mounting substrate 30 of Embodiment 2, has the same effect as the optical semiconductor device 100 of Embodiment 2. The optical semiconductor device 100 of Embodiment 4, which includes the receiving portion mounting substrate 30 of Embodiment 3, has the same effect as the optical semiconductor device 100 of Embodiment 3.

[0071] Implementation Method 5

[0072] Figure 22 This is a diagram illustrating the optical semiconductor device involved in Embodiment 5. Figure 23 It means Figure 22 The diagram shows the light transmission section mounted on the substrate of the receiving section. Figure 24 It means Figure 23 A cross-sectional view of the light-transmitting part. Figure 22 The sectional view shown is consistent with that of Embodiment 1. Figure 3 The corresponding figure. The difference between the optical semiconductor device 100 of Embodiment 5 and the optical semiconductor device 100 of Embodiment 2 is that the substrate of the receiving part mounting substrate 30, which is a non-transmissive substrate through which laser light does not pass, is a glass substrate 36. The main difference from the optical semiconductor device 100 of Embodiment 2 will be explained.

[0073] Because of its high flatness, the glass substrate 36 can improve the placement accuracy of the mounted components. In addition, because the glass substrate 36 is easy to mold, it can be manufactured at a lower cost than metal substrates or ceramic substrates.

[0074] The receiving unit mounting substrate 30 in Embodiment 5 includes a glass substrate 36 and a metal plating layer 31 formed on the inner and outer surfaces of the glass substrate 36. The metal plating layer 31 has openings 33 in the light-transmitting portion 18 of the glass substrate 36 through which the received light 24 passes, and in the light-transmitting portion 19 of the glass substrate 36 through which the local oscillator light 26 passes. Figure 23 The example shown is one where opening 33 is circular. Figure 24 A cross-section of the light-transmitting portion 18 through which the receiving light 24 passes is shown. An opening 33 is formed between dashed lines 83a and 83b, and the area between dashed lines 83a and 83b in the glass substrate 36 forms the light-transmitting portion 18. The light-transmitting portion 18 is the portion of the glass substrate 36 exposed through the opening 33. The light-transmitting portion 19 through which the local oscillator light 26 passes also has the same structure as the light-transmitting portion 18. Furthermore, in Figure 22 In the image, electrode pattern 106 is omitted, and blank space is used to represent opening 33 and the light-transmitting portion exposed through opening 33.

[0075] The received light 24 passes through the opening 33 on the inner side of the receiving unit mounting substrate 30, the light transmission portion 18, and the opening 33 on the outer side of the receiving unit mounting substrate 30, and is input from the transmitting unit 11 to the receiving unit 10. The local oscillator light 26 passes through the opening 33 on the inner side of the receiving unit mounting substrate 30, the light transmission portion 19, and the opening 33 on the outer side of the receiving unit mounting substrate 30, and is input from the transmitting unit 11 to the receiving unit 10. The optical semiconductor device 100 of Embodiment 5 has a metal plating layer 31 formed on the surface of the receiving unit mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface, thus achieving the same effect as the optical semiconductor device 100 of Embodiment 2. A black plating layer 32 may also be formed on the receiving unit mounting substrate 30 instead of the metal plating layer 31. The receiving unit mounting substrate 30 of Embodiment 5, which has a black plating layer 32 formed on the inner and outer sides of the glass substrate 36, achieves the same effect as the optical semiconductor device 100 of Embodiment 3.

[0076] exist Figure 22 The example shown illustrates a metal plating layer 31 formed on the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21 and on the opposite side of that surface. However, it is sufficient to form the metal plating layer 31 on at least the surface of the receiving portion mounting substrate 30 opposite to the semiconductor laser 21. The optical semiconductor device 100 of Embodiment 5, which has a receiving portion mounting substrate 30 with a metal plating layer 31 formed on its inner surface (the surface opposite to the semiconductor laser 21), also achieves the same effect as the optical semiconductor device 100 of Embodiment 5, which has a receiving portion mounting substrate 30 with metal plating layers 31 formed on both its inner and outer surfaces.

[0077] As described above, the optical semiconductor device 100 of Embodiment 5 is an optical semiconductor device that has a semiconductor laser 21 for outputting laser light and a semiconductor light-receiving element 22 for receiving signal light (receiving light 24) from the outside mounted on a package 110, and performs digital coherent optical communication with the outside. The optical semiconductor device 100 of Embodiment 5 includes: a semiconductor laser 21 mounted on the bottom 103 of the package 110; a receiving unit 10 that uses the laser light output from the semiconductor laser 21, i.e., the local oscillator light 26, to receive signal light (receiving light 24) from the outside; and a receiving unit mounting substrate 30 on which the receiving unit 10, including the semiconductor light-receiving element 22, is mounted. The receiving unit 10 is disposed on the side opposite to the side facing the semiconductor laser 21. The receiving substrate 30 is a non-transparent substrate that does not allow laser light to pass through, and has a light-passing portion (light-passing portion 19) through which the local oscillator light 26 output from the semiconductor laser 21 passes. It covers the bottom 103 surrounded by the outer periphery 102 of the package 110, either without a gap 43 or with a gap 43. When the receiving substrate 30 covers the bottom 103 surrounded by the outer periphery 102 of the package 110 with a gap 43, the length (gap length d) of the gap 43 between the outer periphery 102 of the package 110 and the receiving substrate 30 is less than or equal to the thickness (substrate thickness h) of the receiving substrate 30. Furthermore, the substrate of the non-transparent receiving substrate 30 is a laser-transmitting glass substrate 36. The receiving unit mounting substrate 30 has a metal plating layer formed on the surface opposite to the semiconductor laser 21 and on the opposite side of that surface. The metal plating layer has an opening 33 through which the local oscillator light 26 output by the semiconductor laser 21 passes. The light transmission portion (light transmission portion 19) through which the local oscillator light passes is the portion exposed by the opening 33 of the glass substrate. According to this structure, in the optical semiconductor device 100 of Embodiment 5, the semiconductor laser 21 that outputs laser light is mounted on the bottom 103 of the package 110. The receiving unit 10 is mounted on the side opposite to the semiconductor laser 21 of the receiving unit mounting substrate 30, which covers the bottom 103 surrounded by the outer periphery 102 of the package 110, in a state where there is no gap 43 between it and the outer periphery 102 or there is a gap 43. Therefore, even in the case of digital coherent optical communication, it is possible to prevent stray light from the transmitting side to the receiving side while achieving miniaturization.

[0078] Furthermore, in embodiments 1 to 5, an optical semiconductor device 100 for performing digital coherent optical communication was described. However, the three-dimensional configuration in which a transmitting section 11 including a semiconductor laser 21 that outputs laser light and a receiving section 10 including a semiconductor light-receiving element 22 that receives signal light from the outside, i.e., receiving light 24, are sandwiched between a receiving section mounting substrate 30 can also be applied to an optical semiconductor device 100 for performing optical communication different from digital coherent optical communication.

[0079] Furthermore, this application describes various exemplary embodiments and examples, but the various features, forms, and functions described in one or more embodiments are not limited to the application of a specific embodiment, and can also be applied to embodiments individually or in various combinations. Therefore, countless modifications not illustrated can be conceived within the scope of the technology disclosed in this application. For example, these include modifications, additions, or omissions of at least one constituent element, as well as cases where at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0080] Explanation of reference numerals in the attached figures

[0081] 10...Receiver; 13...Aperture (light transmission part); 19...Light transmission part (light transmission section); 21...Semiconductor laser; 22...Semiconductor light receiving element; 24...Received light; 26...Local oscillator light source; 30...Receiver mounting substrate; 31...Metal plating; 32...Black plating; 33...Opening; 35...Conductive connection component; 36...Glass substrate; 37...Non-transparent substrate; 38...Recess; 43...Gap; 100...Optical semiconductor device; 110...Packaging; 102...Outer periphery; 103...Bottom; 104...Substrate placement part; 105...Substrate connection pattern; 108...Grounding pattern; d...Gap length; h...Substrate thickness.

Claims

1. An optical semiconductor device comprising a semiconductor laser for outputting laser light and a semiconductor light-receiving element for receiving signal light from an external source, and for performing digital coherent optical communication with an external source. in, The optical semiconductor device includes: The semiconductor laser is mounted on the bottom of the package; The receiving unit uses the laser light output from the semiconductor laser, i.e., the local oscillator light, to receive the signal light from the outside. as well as The receiving unit is mounted on a substrate and includes the receiving unit containing the semiconductor light-receiving element. The receiving part is disposed on the side opposite to the surface opposite the semiconductor laser. The receiving portion is mounted on a non-transparent substrate that is impermeable to the laser, and has a light-passing portion through which the local oscillator light output by the semiconductor laser passes, and covers the bottom surrounded by the outer periphery of the package in a state where there is no gap between it and the outer periphery of the package or a gap exists. When the receiving portion mounting substrate covers the bottom surrounded by the outer peripheral portion of the package with a gap between it and the outer peripheral portion, the length of the gap between the outer peripheral portion of the package and the receiving portion mounting substrate is less than or equal to the thickness of the receiving portion mounting substrate.

2. The optical semiconductor device according to claim 1, wherein, The receiving unit is mounted on a metal substrate.

3. The optical semiconductor device according to claim 1, wherein, The receiving unit mounting substrate has a metal plating layer formed on the surface opposite to the semiconductor laser.

4. The optical semiconductor device according to claim 3, wherein, The receiving unit mounting substrate has a metal plating layer formed on the side opposite to the surface facing the semiconductor laser.

5. The optical semiconductor device according to claim 1, wherein, The receiving unit mounting substrate has a black coating that absorbs the laser on the surface opposite to the semiconductor laser.

6. The optical semiconductor device according to claim 5, wherein, The receiving unit mounting substrate has a black coating that absorbs the laser on the side opposite to the side facing the semiconductor laser.

7. The optical semiconductor device according to claim 1 or 2, wherein, The receiving unit mounting substrate has multiple recesses formed on the surface opposite to the semiconductor laser to perform multiple reflections of light with the same frequency as the local oscillator light source.

8. The optical semiconductor device according to any one of claims 1 to 6, wherein, The light-passing portion of the receiving unit mounting substrate through which the local oscillator light passes is a hole that penetrates the receiving unit mounting substrate.

9. The optical semiconductor device according to claim 1, wherein, The receiving unit is mounted on a substrate configured as follows: The substrate is a glass substrate through which the laser passes. A metal plating layer is formed on the surface opposite to the semiconductor laser and on the opposite side of the surface. The metal plating layer has an opening through which the local oscillator light emitted by the semiconductor laser passes. The light-passing portion through which the local oscillator light passes is the portion of the glass substrate exposed through the opening.

10. The optical semiconductor device according to any one of claims 1 to 6 and 9, wherein, The package includes: The substrate mounting section is configured to extend inward toward the outer periphery for mounting the receiving section on the substrate; and A metal substrate connection pattern is formed on the substrate placement section and connected to the receiving section mounting substrate via a conductive connection member.

11. The optical semiconductor device according to any one of claims 1 to 6 and 9, wherein, The package includes: The substrate mounting section is configured to extend inward toward the outer periphery for mounting the receiving section on the substrate; and A metallic grounding pattern is formed on the substrate mounting portion and connected to the receiving portion mounting substrate via a conductive connection member. The grounding pattern becomes the grounding potential of the optical semiconductor device.

Images