Optical modulator integrated laser, optical modulator, and optical semiconductor device

Abstract

The invention provides an optical modulator integrated laser, an optical modulator, and an optical semiconductor device, which can reduce the loss of modulation signals caused by reflection. An optical modulator-integrated laser is provided with: a substrate; a laser unit which is provided on the substrate and outputs laser light; a light modulation unit which is provided on the substrate and modulates the laser light; and a first termination portion provided on the substrate and having a first resistive film. The light modulation unit has: a modulation electrode for supplying a modulation signal; a signal pad connected to the modulation electrode and connected to a first wire for inputting a modulation signal to the light modulation unit; and the first bonding pad is used for being connected with a second wire with a ground potential. The modulation electrode is connected to one end of the first resistive film. The other end of the first resistive film is connected to the first pad.

Description

Technical Field

[0001] The present invention relates to a light modulator integrated laser, a light modulator, and an optical semiconductor device. Background Art

[0002] Patent document 1 discloses a technology related to a high-frequency circuit and a module and a communication device equipped with the high-frequency circuit. The high-frequency circuit is configured to connect a signal line transmitting a high-frequency signal to an element having a capacitor using a first bonding wire, and to connect the element having a capacitor to a terminal resistor for impedance matching using a second bonding wire. In the high-frequency circuit, the magnitude of the characteristic impedance of the transmission line formed by the first bonding wire, the second bonding wire, and the element having a capacitor is greater than the magnitude of the characteristic impedance of the input side of the high-frequency signal. In addition, in the high-frequency circuit, the magnitude of the inductance of the first bonding wire is smaller than the magnitude of the inductance of the second bonding wire.

[0003] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2001-308130 Summary of the invention Problems to be solved by the invention With the increase in speed and capacity of optical communication, it is expected that the optical modulator of the optical semiconductor device will have a wider bandwidth. However, when the frequency of the modulated signal is high, such as 100 GHz or more, the electrical reflection of the modulated signal tends to increase. When the reflection of the modulated signal is large, the loss of the modulated signal increases. As a result, for example, there is a risk that the modulated signal cannot be fully transmitted to the optical modulator.

[0004] An object of the present invention is to provide an optical modulator-integrated laser, an optical modulator, and an optical semiconductor device in which loss of a modulated signal due to reflection is reduced.

[0005] Means used to solve problems According to one embodiment of the present invention, an optical modulator integrated laser comprises: a substrate; a laser unit, which is arranged on the substrate and outputs laser light; an optical modulation unit, which is arranged on the substrate and modulates the laser light; and a first terminal unit, which is arranged on the substrate and has a first resistor film. The optical modulation unit comprises: a modulation electrode, which provides a modulation signal; a signal pad, which is connected to the modulation electrode and is used to connect to a first wire, wherein the first wire is used to input a modulation signal to the optical modulation unit; and a first pad, which is used to connect to a second wire having a ground potential. The modulation electrode is connected to one end of the first resistor film. The other end of the first resistor film is connected to the first pad.

[0006] Effects of the Invention According to the present invention, it is possible to provide an optical modulator-integrated laser, an optical modulator, and an optical semiconductor device in which loss of a modulated signal due to reflection is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a plan view showing the small-sized optical device for transmission according to the first embodiment of the present invention.

[0008] Figure 2 This is a circuit diagram showing a circuit included in the small-sized optical device for transmission according to the first embodiment.

[0009] Figure 3 It is a perspective view showing an optical semiconductor device included in the small optical transmission device according to the first embodiment.

[0010] Figure 4 It is a plan view showing the optical semiconductor device according to the first embodiment.

[0011] Figure 5 It is an enlarged view showing the pad, the terminal portion, and the modulation electrode according to the first embodiment.

[0012] Figure 6 is along Figure 4 A cross-sectional view taken along line VI-VI is shown.

[0013] Figure 7 It means manufacturing Figure 4 A cross-sectional view of a portion of a process of manufacturing an optical semiconductor device is shown.

[0014] Figure 8 It is a perspective view showing an optical semiconductor device according to a second embodiment.

[0015] Fig. 9 It is a plan view showing an optical semiconductor device according to a second embodiment.

[0016] Fig.10 It is a perspective view showing an optical semiconductor device according to a first modification.

[0017] Fig.11 It is a plan view showing an optical semiconductor device according to a first modification.

[0018] Fig.12 It is a top view showing an optical semiconductor device as a comparative example.

[0019] Description of Reference Numerals 1: Laser unit; 2: Modulation electrode; 3~5, 7: soldering pad; 3A, 4A: Open; 6. 501~503: substrate; 9, 15, 16, 22, 24, 25, 35, 55, 76~78, 91, 92, 94~98: wire; 10: driving electrode; 17, 23, 66, 87, 117, 119: ground potential wires; 18, 88, 118, 121: signal lines; 19: ground pattern; 31~33: resistance film; 34, 36~38, 65, 84~86, 111, 112, 114~116: wiring pattern; 100, 110, 120: light modulation unit; 101: passivation film; 103: seed layer; 104: resist mask; 200, 210: transmission lines; 300, 310, 320: terminal unit; 504: driver IC; 505: bypass capacitor; 506: Thermistor; 507: Photodiode for monitoring; 508: TEC; 509: packaging; 510: Circuit; A~D: Optical semiconductor devices; a~d: optical modulator integrated semiconductor laser; A1: Small optical device for transmission; A2: Circuit; L: lens; M: outgoing light; P, X: connection end; V: connection point; Q, W, Y: one end; L1, L2: distance. DETAILED DESCRIPTION

[0020] [Description of Embodiments of the Invention] First, the contents of the embodiments of the present invention are listed for explanation. [1] An optical modulator integrated laser according to one embodiment of the present invention comprises: a substrate; a laser unit, which is arranged on the substrate and outputs laser light; an optical modulator, which is arranged on the substrate and modulates the laser light; and a first terminal, which is arranged on the substrate and has a first resistor film. The optical modulator comprises: a modulation electrode, which provides a modulation signal; a signal pad, which is connected to the modulation electrode and is used to connect to a first wire, the first wire is used to input the modulation signal to the optical modulator; and a first pad, which is used to connect to a second wire with a ground potential. The modulation electrode and one end of the first resistor film are connected to each other. The other end of the first resistor film and the first pad are connected to each other. An optical modulator according to one embodiment of the present invention comprises: a substrate; an optical modulator, which is arranged on the substrate and modulates the laser light; and a first terminal, which is arranged on the substrate and has a first resistor film. The optical modulator comprises: a modulation electrode, which provides a modulation signal; a signal pad, which is connected to the modulation electrode and is used to connect to the first wire, the first wire is used to input the modulation signal to the optical modulator; and a first pad, which is used to connect to a second wire with a ground potential. The modulation electrode and one end of the first resistor film are connected to each other. The other end of the first resistance film is connected to the first pad.

[0021] In the optical modulator integrated laser and optical modulator of the above-mentioned [1], the modulation electrode, the first pad, and the first resistor film included in the first terminal are arranged on the same substrate. Therefore, the distance of the conductive path between the modulation electrode and one end of the first resistor film can be set to be extremely short. As a result, the electrical reflection of the modulation signal at one end of the first resistor film of the first terminal can be reduced. Therefore, the optical modulator integrated laser and optical modulator in which the loss of the modulation signal caused by reflection is reduced can be obtained.

[0022] [2] In the optical modulator integrated laser and optical modulator of [1], the distance of the conductive path between the modulation electrode and one end of the first resistor film can be less than 1 / 4 of the wavelength of the modulation signal. According to the inventors' understanding, as long as the distance of the conductive path between the modulation electrode and one end of the first resistor film is less than 1 / 4 of the wavelength of the modulation signal, even if the frequency of the input modulation signal is a high frequency such as 100 GHz or more, the electrical reflection of the modulation signal at one end of the first resistor film of the first terminal portion is not likely to increase. Therefore, the loss of the modulation signal caused by reflection can be effectively reduced.

[0023] [3] The optical modulator integrated laser and optical modulator of [1] or [2] above may further include a second terminal, which is arranged on the substrate and has a second resistor film. The optical modulator may further include a second pad, which is arranged on the side opposite to the first pad relative to the signal pad, and is used to connect to a third wire having a ground potential. Alternatively, the modulation electrode and one end of the second resistor film are connected to each other. Alternatively, the other end of the second resistor film is connected to the second pad. In the optical modulator integrated laser and optical modulator of [3] above, the third wire connected to the second pad has a ground potential. Therefore, the modulation signal of the first wire connected to the signal pad arranged between the first pad and the second pad becomes a form sandwiched by the ground potential. As a result, the mismatch of the input impedance is further reduced, and the loss of the modulation signal caused by the mismatch of the input impedance is further reduced. In addition, the modulation electrode, the second pad and the second resistor film included in the second terminal are arranged on the same substrate. Therefore, the distance of the conductive path between the modulation electrode and one end of the second resistor film can be set to be extremely short. This can reduce the electrical reflection of the modulation signal at one end of the second resistor film of the second terminal portion, thereby achieving an optical modulator integrated laser and an optical modulator in which the loss of the modulation signal due to reflection is further reduced.

[0024] [4] In the optical modulator integrated laser and optical modulator of [3], the distance of the conductive path between the modulation electrode and one end of the second resistor film can be less than 1 / 4 of the wavelength of the modulation signal. Thus, as in the optical modulator integrated laser and optical modulator of [2], the loss of the modulation signal caused by reflection at one end of the second resistor film is reduced.

[0025] [5] Any of the optical modulators in [1] to [4] may further include a laser unit for outputting laser light disposed on a substrate. Thus, the laser unit and the optical modulator unit can be formed as a single chip on the same substrate. Thus, miniaturization of the optical transmission device can be achieved.

[0026] [6] An optical semiconductor device according to one embodiment of the present invention comprises the optical modulator of [1] or [2] above, and a transmission line for transmitting a modulated signal. The transmission line comprises: a signal line for transmitting the modulated signal; and a first ground potential line having a ground potential and arranged in parallel with the signal line. The signal pad is connected to the signal line via a first conductive wire. The first pad is connected to the first ground potential line via a second conductive wire.

[0027] In the optical semiconductor device [6] described above, the first pad is connected to the ground potential line through the second conductor. Thus, the second conductor having the ground potential can be provided on the optical modulator. The signal line is connected to the first conductor. The ground potential line is connected to the second conductor. Thus, the first conductor and the second conductor are arranged in parallel with each other. Therefore, after leaving the signal line, the modulated signal also travels in parallel with the ground potential. Thus, the impedance mismatch between the signal line and the first conductor is reduced. Thus, the loss of the modulated signal caused by the impedance mismatch is reduced.

[0028] [7] An optical semiconductor device according to one embodiment of the present invention comprises the optical modulator of [3] or [4] above, and a transmission line for transmitting a modulated signal. The transmission line comprises: a signal line for transmitting a modulated signal; and a first ground potential line and a second ground potential line having a ground potential and arranged in parallel with the signal line. The signal pad is connected to the signal line via a first conductor. The first pad is connected to the first ground potential line via a second conductor. The second pad is connected to the second ground potential line via a third conductor. The third conductor is arranged on the side opposite to the second conductor relative to the first conductor.

[0029] In the optical semiconductor device of the above-mentioned [7], the second pad is connected to the ground potential line through the third wire, so the third wire has a ground potential. Therefore, the first wire arranged in parallel with the second wire and the third wire is in a state of being sandwiched by the ground potential. Therefore, the modulated signal passing through the first wire travels while being sandwiched by the ground potential. Thus, the impedance mismatch between the signal line and the first wire is further reduced. Therefore, the loss of the modulated signal caused by the impedance mismatch is further reduced.

[0030] [Details of the embodiments of the present invention] Hereinafter, specific examples of the optical modulator integrated laser, optical modulator, and optical semiconductor device of the present invention are described with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all changes within the meaning and scope equivalent to the claims. In the following description, the same reference numerals are marked on the same elements in the description of the drawings, and repeated descriptions are omitted.

[0031] (First embodiment) Figure 1 It is a plan view showing a small-sized optical device A1 for transmission according to the first embodiment of the present invention. Figure 2 2 is a circuit diagram showing a circuit A2 included in the small-sized optical transmission device A1 according to the first embodiment. Figure 1 as well as Figure 2 , the structure of the small optical device A1 for transmission is explained.

[0032] like Figure 1As shown, the small optical device A1 for transmission includes a package 509, a substrate 501 (Chip on Carrier), a substrate 502 (Mount Carrier), and a substrate 503. The package 509 accommodates the substrate 501, the substrate 502, and the substrate 503. The substrate 502 and the substrate 503 are arranged in parallel. The substrate 501 is arranged on the substrate 502. The material of the substrate 501 and the substrate 502 is an insulator such as ceramic.

[0033] On the substrate 503, there are provided wiring patterns 111, wiring patterns 112, wiring patterns 114, wiring patterns 115, wiring patterns 116, ground potential lines 117, ground potential lines 119, signal lines 118, signal lines 121, and a driver IC 504. The wiring patterns 111, wiring patterns 112, wiring patterns 114, wiring patterns 115, wiring patterns 116, ground potential lines 117, and signal lines 118 extend from one side wall of the package 509 toward the substrate 502, and are connected to an external circuit of the small optical device A1 for transmission via terminals not shown. The wiring patterns 111, wiring patterns 112, wiring patterns 114, wiring patterns 115, wiring patterns 116, ground potential lines 117, ground potential lines 119, signal lines 118, and signal lines 121 are made of, for example, metal. The signal line 118 transmits a high frequency modulated signal input from outside the small optical device A1 for transmission. The ground potential line 117 has a ground potential (reference potential) input from the circuit 510 outside the small optical device A1 for transmission. The signal line 118 and the ground potential line 117 constitute a transmission line. The ground potential line 119 and the signal line 121 also constitute a transmission line.

[0034] The input terminal of the driver IC 504 is connected to the ground potential line 117 and the signal line 118. The output terminal of the driver IC 504 is connected to the ground potential line 119 and the signal line 121. The driver IC 504 amplifies the modulated signal from the signal line 118 and outputs the amplified modulated signal to the signal line 121.

[0035] Also refer to Figure 1 as well as Figure 2. A wiring pattern 84, a wiring pattern 85, a wiring pattern 86, a ground potential line 87, a signal line 88, a thermistor 506, a monitoring photodiode 507, and a lens L are provided on the substrate 502. The wiring pattern 86 is connected to the wiring pattern 116 via a wire 96. The wiring pattern 85 is connected to the wiring pattern 115 via a wire 95. The wiring pattern 84 is connected to the wiring pattern 114 via a wire 94. The ground potential line 87 is connected to the ground potential line 119 via a wire 97. The signal line 88 is connected to the signal line 121 via a wire 98. The material of the wiring pattern 84, the wiring pattern 85, the wiring pattern 86, the ground potential line 87, and the signal line 88 is, for example, metal. The wiring pattern 84, the wiring pattern 85, the wiring pattern 86, the ground potential line 87, and the signal line 88 are formed on an insulator, for example, by vapor deposition and subsequent peeling, or sputtering.

[0036] The thermistor 506 is provided on the wiring pattern 86. The thermistor 506 shows a resistance value that depends on temperature. The resistance value is detected by a circuit outside the small optical transmission device A1 via the wiring pattern 86, the lead wire 96, and the wiring pattern 116.

[0037] The monitoring photodiode 507 is connected between the wiring pattern 84 and the ground potential line 87. In order to make the average intensity of the emitted light M constant, the monitoring photodiode 507 detects the back light emitted from the optical modulator integrated semiconductor laser a (described later) of the optical semiconductor device A. The monitoring photodiode 507 outputs an electrical signal corresponding to the intensity of the back light to the external circuit of the small optical device A1 for transmission via the wiring pattern 84, the wire 94, and the wiring pattern 114. The lens L is optically coupled to the light emission end of the optical semiconductor device A to parallelize (collimate) the emitted light M emitted from the optical modulator integrated semiconductor laser a.

[0038] A temperature control element (TEC) 508 is provided on the back side of the substrate 502 (only Figure 2 ). One electrode of TEC508 is connected to wiring pattern 111 through wire 91. The other electrode of TEC508 is connected to wiring pattern 112 through wire 92. The power for driving TEC508 is input from the external circuit of small-sized optical device A1 for transmission via wiring pattern 111 and wiring pattern 112. The external circuit of small-sized optical device A1 for transmission controls the magnitude of the power for driving TEC508 based on the ambient temperature of optical semiconductor device A (i.e., the resistance value of thermistor 506). As a result, the temperature of optical modulator integrated semiconductor laser a is maintained at a predetermined temperature, and the wavelength of output light M output from optical semiconductor device A is maintained at a predetermined wavelength.

[0039] A ground potential line 66, a wiring pattern 65, a bypass capacitor 505, and an optical semiconductor device A are provided on the substrate 501. One end of the ground potential line 66 is connected to a ground terminal of the thermistor 506 via a wire 76, and the other end of the ground potential line 66 is connected to a ground pattern 19 (described later). The material of the ground potential line 66 is, for example, metal. The ground potential line 66 has a ground potential.

[0040] The bypass capacitor 505 is provided on the ground potential line 66. The lower surface electrode of the bypass capacitor 505 is connected to the ground potential line 66. The upper surface electrode of the bypass capacitor 505 is connected to the wiring pattern 65 through the wire 55. The material of the wiring pattern 65 is metal, for example.

[0041] Figure 3 It is a perspective view showing an optical semiconductor device A included in a small optical transmission device A1. Figure 4 is a top view showing the optical semiconductor device A. Figure 3 as well as Figure 4 As shown, the optical semiconductor device A includes an optical modulator integrated semiconductor laser a, a ground pattern 19, and a transmission line 200. The ground pattern 19 is provided on a substrate 501. The material of the ground pattern 19 is, for example, metal. The ground pattern 19 has a ground potential.

[0042] The transmission line 200 includes a ground potential line 17 (first ground potential line) and a signal line 18. The ground potential line 17 is arranged in parallel with the signal line 18 in a direction intersecting the extending direction of the ground potential line 17. The material of the ground potential line 17 and the signal line 18 is, for example, metal. Figure 1 As shown, one end of the ground potential line 17 is connected to the ground potential line 87 through the conductor 77. The ground potential line 17 has a ground potential. Figure 1 As shown, one end of the signal line 18 is connected to the signal line 88 through the conductor 78. The signal line 18 transmits the amplified modulated signal.

[0043] The optical modulator integrated semiconductor laser a described in this embodiment is an example of the optical modulator of the present invention. The optical modulator integrated semiconductor laser a is provided on the ground pattern 19, and includes a substrate 6, a laser unit 1, an optical modulator 100, and a terminal 300 (first terminal). The substrate 6 is in a rectangular parallelepiped shape. The laser unit 1 is arranged on the substrate 6 on the substrate 503 side relative to the optical modulator 100. In addition, as Figure 1As shown, the laser unit 1 is sandwiched between the transmission line 200 and the ground potential line 66. The laser unit 1 has an active area, and a laser with a constant light intensity over time is generated by supplying current to the active area. In addition, the laser unit 1 has a driving electrode 10 and a pad 7 on the surface. The driving electrode 10 extends along the laser resonance direction (the arrangement direction of the laser unit 1 and the optical modulation unit 100) and supplies current to the active area. The pad 7 is arranged in a direction intersecting the extension direction of the driving electrode 10 relative to the driving electrode 10 and is connected to the driving electrode 10. The pad 7 is connected to the upper surface electrode of the bypass capacitor 505 through the wire 9. Thus, the driving current is supplied to the driving electrode 10 from the outside of the small optical device A1 for transmission via the wiring pattern 115, the wiring pattern 85, the wiring pattern 65, the upper surface electrode of the bypass capacitor 505 and the pad 7.

[0044] The light modulator 100 is arranged on the lens L side relative to the laser unit 1. The light modulator 100 modulates the laser output from the laser unit 1 and outputs the modulated output light M. The above-mentioned back light is the laser output from the laser unit 1 without passing through the light modulator 100. The laser unit 1 and the light modulator 100 are formed as a single chip on the substrate 6. In addition, the light modulator 100 includes a modulation electrode 2, a pad 3 (a first pad) and a pad 4 (a signal pad). The light modulator 100 has a modulation area, and the laser is transmitted or blocked according to the supply of current to the modulation area, thereby modulating the laser. The modulation electrode 2 supplies a modulation current (modulation signal) to the modulation area. As a result, in the modulation area, the laser is passed or blocked based on the input modulation signal. The modulation electrode 2 extends in the same direction as the direction of travel of the laser when viewed from above. On the upper surface of the light modulator integrated semiconductor laser a, the modulation electrode 2 is arranged approximately in the center in a direction orthogonal to the direction of travel of the laser.

[0045] The pad 3 and the pad 4 are arranged on the transmission line 200 side relative to the modulation electrode 2. The pad 4 is arranged in the center of the traveling direction of the laser in the optical modulation unit 100. The pad 4 is connected to the modulation electrode 2 and is connected to the wire 16 (first wire) for inputting the modulation signal to the optical modulation unit 100. The pad 3 is arranged in parallel with the pad 4 along the long side direction of the modulation electrode 2 and is arranged on the laser unit 1 side relative to the pad 4. The pad 3 is connected to the wire 15 (second wire) having a ground potential. The pad 3 and the pad 4 are film-shaped and have a substantially rectangular shape when viewed from above. The material of the pad 3 and the pad 4 is metal, for example, gold (Au). The film thickness of the pad 3 and the pad 4 is, for example, greater than 3 μm and less than 10 μm.

[0046] The other end of the ground potential line 17 is in contact with the ground pattern 19 and is connected to the pad 3 through the wire 15. The other end of the signal line 18 is connected to the pad 4 through the wire 16. The wire 15 and the wire 16 are arranged in parallel. Figure 4 As shown, in one example, the wires 15 and 16 are arranged parallel to each other in a plan view. The wires 15 and 16 are bonding wires made of Au, for example. The cross-sectional diameter of the wires 15 and 16 is, for example, 25 μm. The interval between the wires 15 and 16 is, for example, several tens of μm.

[0047] The terminal portion 300 is provided between the pad 3 and the modulation electrode 2. The terminal portion 300 includes a resistance film 31 (first resistance film) and reduces reflection of the modulation signal. Figure 5 3 is an enlarged view showing the pad 3, the terminal portion 300 and the modulation electrode 2 involved in the first embodiment. The modulation electrode 2 and one end Y of the resistor film 31 are connected to each other via the wiring pattern 38. The other end of the resistor film 31 is connected to the pad 3. The distance (electrical length) L1 of the conductive path between the connection end X of the modulation electrode 2 and the one end Y of the resistor film 31 is less than 1 / 4 of the wavelength of the modulation signal, or less than 1 / 8, or less than 1 / 10, or less than 1 / 12, and is 1 / 1000 or more. As a specific example, when the wavelength of the modulation signal is, for example, 1200μm, L1 is less than 300μm, or less than 150μm, or less than 120μm, or less than 100μm, and is 1μm or more. The resistor film 31 is rectangular in shape. The material of the resistor film 31 is, for example, a metal such as nickel chromium (NiCr), titanium tungsten (TiW), tantalum nitride (TaN) or platinum (Pt). The film thickness of the resistor film 31 is, for example, greater than 100 nm and less than 300 nm. The resistor film 31 is composed of a resistor pattern of a thin film formed by evaporation and subsequent peeling, or sputtering. When the impedance value of the light absorbing layer is, for example, 90Ω, by setting the resistance value of the resistor film 31 to, for example, 110Ω, the terminal impedance value becomes 50Ω. It should be noted that in most cases, the terminal impedance value is usually 50Ω, but it also includes a case where it is different from 50Ω due to the addition of a capacitor or inductor, or the adjustment of the resistance value.

[0048] Figure 6 is along Figure 4The cross-sectional view along the line VI-VI shown. The light modulator 100 has a passivation film 101 and a seed layer 103 (SEED layer) on a substrate 6. The substrate 6 is in contact with the ground pattern 19 and is disposed on the ground pattern 19. The substrate 6 is composed of, for example, SI-InP, n-InP, or a dielectric layer. The passivation film 101 is disposed on the substrate 6. The material of the passivation film 101 is, for example, an insulator such as SiO2 or SiN. The film thickness of the passivation film 101 is, for example, greater than 300 nm and less than 500 nm. The resistor film 31 is disposed on the passivation film 101. The pad 3 and the wiring pattern 38 are disposed on the passivation film 101, and have a portion disposed on the resistor film 31 and a portion disposed in an area without the resistor film 31. The seed layer 103 is disposed between the pad 3 and the wiring pattern 38 and the passivation film 101, and between the pad 3 and the wiring pattern 38 and the resistor film 31. The material of the seed layer 103 is, for example, gold (Au). The thickness of the seed layer 103 is, for example, not less than 100 nm and not more than 200 nm. The pad 3 and the wiring pattern 38 are not in contact with each other, and the resistive film 31 has portions exposed from the pad 3 and the wiring pattern 38 .

[0049] Figure 7 It means manufacturing Figure 4 A cross-sectional view of a portion of the process of manufacturing the optical semiconductor device A shown in FIG. A portion of the manufacturing process of the optical semiconductor device A will be described. In the optical modulation unit 100, a substrate 6 is first prepared. Next, a passivation film 101 is formed on the substrate 6. Thereafter, a resist mask (not shown) is formed on the surface of the passivation film 101 by photolithography, and a resistor film 31 is formed on the passivation film 101. Next, a seed layer 103 is formed on the surfaces of the resistor film 31 and the passivation film 101. Thereafter, a resist mask 104 having an opening 3A and an opening 4A is formed on the surface of the seed layer 103 by photolithography. Next, gold plating is performed on the opening 3A and the opening 4A, thereby forming a pad 3 in the opening 3A and forming a wiring pattern 38 in the opening 4A. Finally, the resist mask 104 is removed from the optical modulation unit 100, and the seed layer 103 is removed using the pad 3 and the wiring pattern 38 as a mask. Thus, a Figure 6 The pad 3, the terminal portion 300 and the wiring pattern 38 are shown.

[0050] Effects obtained by the optical semiconductor device A having the above-described structure will be described. Fig.12: is a top view showing an optical semiconductor device D as a comparative example. The optical semiconductor device D is different from the optical semiconductor device A in the following respects. The optical semiconductor device D is provided with an optical modulator integrated semiconductor laser d and a terminal portion 320 instead of the optical modulator integrated semiconductor laser a. The optical modulator integrated semiconductor laser d is provided with an optical modulator 130 instead of the optical modulator 100. The optical modulator 130 is arranged on the lens side (not shown) relative to the laser unit 1. The pad 3, the wire 15, the wire 24 and the terminal portion 300 are not provided in the optical modulator 130. The terminal portion 320 is provided on the substrate 501 on the side opposite to the transmission line 200 relative to the optical modulator 130. In the terminal portion 320, a wiring pattern 34, a wiring pattern 36 and a resistor film 33 are provided along the arrangement direction of the laser unit 1 and the optical modulator 130. The resistor film 33 is arranged between the wiring pattern 34 and the wiring pattern 36. The wiring pattern 34 is connected to the pad 4 through the wire 35. The wiring pattern 36 is in contact with the ground pattern 19. In the optical semiconductor device D, the terminal 320 is arranged outside the optical modulator integrated semiconductor laser d, so the length of the transmission path from one end W of the resistor film 33 of the terminal 320 to the connection point V of the wire 16 and the pad 4 becomes larger. In this case, the impedance mismatch becomes larger, so the electrical reflection of the modulation signal in the resistor film 33 caused by the broadbandization of the optical modulator integrated semiconductor laser is likely to become larger. In contrast, in the above-mentioned optical semiconductor device A, the modulation electrode 2, the pad 3, and the resistor film 31 included in the terminal 300 are arranged on the same substrate 6. Therefore, the distance L1 of the conductive path between the connection end X of the modulation electrode 2 and one end Y of the resistor film 31 can be reduced. Therefore, in the optical semiconductor device A, the electrical reflection of the modulation signal in the resistor film 31 of the terminal 300 is not easy to become larger. Therefore, the optical modulator integrated semiconductor laser a with reduced loss of the modulation signal can be obtained.

[0051] In addition, in the optical semiconductor device A, the pad 3 is connected to the ground potential line 17 through the wire 15. Thus, the wire 15 having the ground potential can be provided on the optical modulator integrated semiconductor laser a. The signal line 18 is connected to the wire 16. The ground potential line 17 is connected to the wire 15. Thus, the wire 15 and the wire 16 are arranged in parallel with each other. Therefore, after leaving the signal line 18, the modulated signal also travels in parallel with the ground potential. Thus, the impedance mismatch between the signal line 18 and the wire 16 is reduced. Therefore, the loss of the modulated signal caused by the impedance mismatch of the modulated signal is reduced.

[0052] As in the present embodiment, the distance L1 of the conductive path between the connection end X of the modulation electrode 2 and the end Y of the resistor film 31 can be less than 1 / 4 of the wavelength of the modulation signal. According to the inventors' understanding, as long as the distance of the conductive path between the connection end X of the modulation electrode 2 and the end Y of the resistor film 31 is less than 1 / 4 of the wavelength of the modulation signal, even if the frequency of the input modulation signal is a high frequency of, for example, 100 GHz or more, the electrical reflection of the modulation signal in the end Y of the resistor film 31 is not easy to increase. Therefore, the loss of the modulation signal caused by reflection can be effectively reduced. It should be noted that, preferably, in 100 Gbps communication, the value of 1 / 4 of the wavelength of the modulation signal is, for example, 300 μm, and the distance L1 is, for example, set to be less than 100 μm.

[0053] As in this embodiment, in the optical semiconductor device A, the resistor film 31 may include at least one material selected from the group consisting of nickel chromium, titanium tungsten, tantalum nitride, and platinum. This improves the close contact between the resistor film 31 and the passivation film 101 and enables a desired resistance value to be obtained.

[0054] As in this embodiment, the conductors 15 and 16 can be arranged parallel to each other in the optical semiconductor device A. The conductors 15 and 16 are arranged parallel to each other, thereby further reducing the impedance mismatch between the signal line 18 and the conductor 16. Therefore, the loss of the modulated signal caused by the impedance mismatch is further reduced.

[0055] As in this embodiment, the laser unit 1 that outputs laser light can be provided on the substrate 6. Thus, the laser unit 1 and the light modulation unit 100 can be monolithically configured on the same substrate 6, and the small-sized transmitting optical device A1 can be miniaturized.

[0056] (Second embodiment) Figure 8 It is a perspective view showing an optical semiconductor device B according to the second embodiment. Fig. 9 : is a top view showing an optical semiconductor device B. The optical semiconductor device B is different from the optical semiconductor device A in the following aspects, and is the same in other aspects. The optical semiconductor device B has an optical modulator integrated semiconductor laser b instead of the optical modulator integrated semiconductor laser a, and has a transmission line 210 instead of the transmission line 200. The optical modulator integrated semiconductor laser b has an optical modulation unit 110 instead of the optical modulation unit 100. The other structures of the optical modulator integrated semiconductor laser b are the same as those of the optical modulator integrated semiconductor laser a.

[0057] The optical modulator integrated semiconductor laser b further has a terminal portion 310 (second terminal portion) on the basis of the terminal portion 300, and the optical modulation portion 110 further has a pad 5 (second pad) on the basis of the pads 3 and 4. The pad 5 is arranged on the substrate 6 on the side opposite to the pad 3 relative to the pad 4, and is connected to the wire 22 (third wire) having a ground potential. The pad 5 is film-shaped and has a substantially rectangular shape when viewed from above. The material of the pad 5 is metal, for example, gold (Au). The film thickness of the pad 5 is, for example, greater than 3 μm and less than 10 μm.

[0058] The terminal portion 310 has a resistor film 32 (second resistor film) to reduce the reflection of the modulation signal. The terminal portion 310 is provided on the substrate 6. One end of the resistor film 32 is connected to the modulation electrode 2 via the wiring pattern 37. The other end of the resistor film 32 is connected to the pad 5. The distance (electrical length) L2 of the conductive path between the connection end P of the modulation electrode 2 and one end Q of the resistor film 32 is less than 1 / 4 of the wavelength of the modulation signal, or less than 1 / 8, or less than 1 / 10, or less than 1 / 12, and is greater than 1 / 1000. As a specific example, when the wavelength of the modulation signal is, for example, 1200 μm, L2 is less than 300 μm, or less than 150 μm, or less than 120 μm, or less than 100 μm, and is greater than 1 μm. The resistor film 32 is in a rectangular shape. The material of the resistor film 32 is, for example, a metal such as nickel chromium (NiCr), titanium tungsten (TiW), tantalum nitride (TaN) or platinum (Pt). The film thickness of the resistor film 32 is, for example, not less than 100 nm and not more than 300 nm. The resistor film 32 is formed by evaporation, stripping, sputtering, or the like. When the impedance value of the light absorbing layer is, for example, 90Ω, by setting the resistance value of the resistor film 32 to, for example, 220Ω, the terminal impedance value becomes 50Ω. It should be noted that in most cases, the terminal impedance value is usually 50Ω, but it also includes a case where it is different from 50Ω due to the addition of a capacitor or an inductor, or the adjustment of the resistance value.

[0059] The transmission line 210 includes a signal line 18, a ground potential line 17, and a ground potential line 23 (second ground potential line). The ground potential line 23 is connected to the pad 5 via a conductor 22. The signal line 18 transmits a modulated signal, and the ground potential lines 17 and 23 have a ground potential.

[0060] The wire 22 is provided on the opposite side of the wire 15 with respect to the wire 16. The wire 22 is a bonding wire made of, for example, Au. The diameter of the cross section of the wire 22 is, for example, 25 μm.

[0061] In the optical semiconductor device B having the above structure, if the pad 5 is connected to the ground potential line 23 through the wire 22, the wire 22 has a ground potential. Therefore, the wire 16 arranged in parallel with the wire 15 and the wire 22 is in a state of being sandwiched by the ground potential. Therefore, the modulation signal passing through the wire 16 travels while being sandwiched by the ground potential. As a result, the impedance mismatch between the signal line 18 and the wire 16 is further reduced. Therefore, the loss of the modulation signal caused by the impedance mismatch is further reduced. In addition, the modulation electrode 2, the pad 5 and the resistor film 32 are arranged on the same substrate 6. Therefore, the distance L2 of the conductive path between the connection end P of the modulation electrode 2 and the end Q of the resistor film 32 can be set to be extremely short. As a result, the electrical reflection of the modulation signal in the end Q of the resistor film 32 can be reduced. Therefore, an optical modulator in which the loss of the modulation signal caused by the reflection is further reduced can be obtained.

[0062] As in this embodiment, the distance L2 of the conductive path between the connection end P of the modulation electrode 2 and the end Q of the resistor film 32 can be less than 1 / 4 of the wavelength of the modulation signal. This can effectively reduce the loss of the modulation signal caused by reflection at the end Q of the resistor film 32.

[0063] (First Modification) Fig.10 It is a perspective view showing an optical semiconductor device C according to a first modification. Fig.11 1 is a top view showing an optical semiconductor device C. The optical semiconductor device C is different from the optical semiconductor device A in the following aspects, but is the same in other aspects. The optical semiconductor device C includes an optical modulator integrated semiconductor laser C instead of the optical modulator integrated semiconductor laser A, and includes a transmission line 220 instead of the transmission line 200. The optical modulator integrated semiconductor laser C includes an optical modulator 120 instead of the optical modulator 100. The other structures of the optical modulator integrated semiconductor laser C are the same as those of the optical modulator integrated semiconductor laser A.

[0064] In the light modulation unit 120, the pad 3 is arranged on the side opposite to the laser unit 1 with respect to the pad 4, and the pad 4 is arranged on the laser unit 1 side with respect to the pad 3. That is, in the light modulation unit 120, the position of the pad 3 and the position of the pad 4 are exchanged with respect to the light modulation unit 100. The terminal unit 300 is arranged on the side opposite to the laser unit 1 with respect to the pad 4.

[0065] In the transmission line 220, the signal line 18 is arranged on the laser unit 1 side with respect to the ground potential line 17, and the ground potential line 17 is arranged on the opposite side of the laser unit 1 with respect to the signal line 18. That is, in the transmission line 220, the position of the signal line 18 and the position of the ground potential line 17 are switched with respect to the transmission line 220.

[0066] The optical semiconductor device C having the above configuration can also obtain the same effects as those of the optical semiconductor device A.

[0067] The optical modulator integrated laser, optical modulator and optical semiconductor device according to the present invention are not limited to the above-mentioned embodiments and various modifications, and various other modifications can be performed. For example, in the above-mentioned embodiments, an example in which the wire 15 and the wire 16 are parallel to each other is shown, but the wire 15 and the wire 16 can also be inclined to each other. Similarly, in the first modification, the wire 22 and the wire 16 can also be inclined to each other. Even in this case, the above-mentioned effect can be exerted by arranging the wire 15 and the wire 16 in parallel (or the wire 16 is sandwiched between the wire 15 and the wire 22).

[0068] In addition, in the above embodiment, the ground potential line 17 and the signal line 18 of the transmission line 200 are provided in parallel on the substrate 502, but the transmission line is not limited to this method. For example, even when the transmission line is configured as a so-called microstrip line in which the ground potential line is provided on the back side of the substrate 501, the above effect can be exerted.

Claims

1. An optical modulator integrated laser, wherein: The optical modulator integrated laser has: substrate; A laser unit, disposed on the substrate, outputting laser light; a light modulator, disposed on the substrate, for modulating the laser light; and The first terminal portion is disposed on the substrate and has a first resistance film. The light modulation unit has: A modulation electrode, providing a modulation signal; A signal pad connected to the modulation electrode and used to be connected to a first wire, wherein the first wire is used to input the modulation signal to the optical modulation unit; as well as A first pad is used to connect to a second wire having a ground potential. The modulation electrode is connected to one end of the first resistance film. The other end of the first resistance film is connected to the first pad.

2. The optical modulator integrated laser according to claim 1, wherein: A distance of a conductive path between the modulation electrode and the one end of the first resistance film is less than ¼ of a wavelength of the modulation signal.

3. The optical modulator integrated laser according to claim 1 or 2, wherein: The optical modulator integrated laser further comprises a second terminal portion, which is provided on the substrate and has a second resistance film. The optical modulation unit further includes a second pad, which is provided on the opposite side of the first pad relative to the signal pad and is used to connect to a third wire having the ground potential. The modulation electrode is connected to one end of the second resistance film. The other end of the second resistance film is connected to the second pad.

4. The optical modulator integrated laser according to claim 3, wherein: A distance of a conductive path between the modulation electrode and the one end of the second resistance film is less than 1 / 4 of a wavelength of the modulation signal.

5. An optical modulator, wherein: The optical modulator comprises: substrate; a light modulation unit, disposed on the substrate, for modulating laser light; and The first terminal portion is disposed on the substrate and has a first resistance film. The light modulation unit has: A modulation electrode, providing a modulation signal; A signal pad connected to the modulation electrode and used to be connected to a first wire, wherein the first wire is used to input the modulation signal to the optical modulation unit; as well as A first pad is used to connect to a second wire having a ground potential. The modulation electrode is connected to one end of the first resistance film. The other end of the first resistance film is connected to the first pad.

6. The optical modulator according to claim 5, wherein: A distance of a conductive path between the modulation electrode and the one end of the first resistance film is less than ¼ of a wavelength of the modulation signal.

7. The optical modulator according to claim 5 or 6, wherein: The optical modulator further includes a second terminal portion, which is provided on the substrate and has a second resistance film. The optical modulation unit further includes a second pad, which is provided on the opposite side of the first pad relative to the signal pad and is used to connect to a third wire having the ground potential. The modulation electrode is connected to one end of the second resistance film. The other end of the second resistance film is connected to the second pad.

8. The optical modulator according to claim 7, wherein: A distance of a conductive path between the modulation electrode and the one end of the second resistance film is less than 1 / 4 of a wavelength of the modulation signal.

9. The optical modulator according to any one of claims 5 to 8, wherein: The optical modulator further includes a laser unit that is provided on the substrate and outputs the laser light.

10. An optical semiconductor device, wherein: The optical semiconductor device comprises: The optical modulator according to claim 5 or 6; and a transmission line for transmitting the modulated signal, The transmission line has: A signal line for transmitting the modulated signal; as well as A first ground potential line having the ground potential and arranged in parallel with the signal line, The signal pad is connected to the signal line through the first wire. The first pad is connected to the first ground potential line through the second wire.

11. An optical semiconductor device, wherein: The optical semiconductor device comprises: The optical modulator according to claim 7 or 8; a transmission line for transmitting the modulated signal, The transmission line has: A signal line for transmitting the modulated signal; as well as A first ground potential line and a second ground potential line have the ground potential and are arranged in parallel with the signal line. The signal pad is connected to the signal line through the first wire. The first pad is connected to the first ground potential line through the second wire, The second pad is connected to the second ground potential line through the third wire, The third conductive line is provided on a side of the first conductive line opposite to the second conductive line.

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