Optical Transmitter Module

Abstract

The optical transmission module comprises: a plurality of semiconductor lasers (8a, 8b) arranged on a secondary support (4) fixed to the side of a block (2), the block (2) being fixed to a plate-shaped metal stem (1); and a cap on which a lens (12) is fixed and covers all components arranged on the stem (1), wherein the optical transmission module is constructed such that: a plurality of lead pins (3a, 3b) of the same number as the plurality of semiconductor lasers (8a, 8b) respectively penetrate a plurality of holes arranged on the stem (1), each of the plurality of lead pins (3a, 3b) is electrically connected to each of the plurality of semiconductor lasers (8a, 8b), a single-phase electrical signal for setting the stem to a ground potential is applied from an external power supply to each of the plurality of semiconductor lasers (8a, 8b) through each of the plurality of lead pins (3a, 3b), and the plurality of semiconductor lasers (8a, 8b) are modulated and oscillated.

Description

Technical Field

[0001] The present application relates to an optical transmission module. Background Art

[0002] Since semiconductor lasers for optical communication output laser light as modulated light that is turned on and off at high speed, they are modularized into a structure that not only oscillates the semiconductor laser, but also inputs an electrical signal for modulating the laser light at high speed and outputs the modulated laser light. One of the module structures is a CAN package type optical transmission module in which a modulated semiconductor laser is arranged in a cylindrical CAN package (cap).

[0003] In order to achieve a structure that outputs lasers of multiple wavelengths in the CAN package type optical transmission module, a structure is proposed in which multiple EML (Electro-absorption Modulated Laser Diode) elements that output lasers of different wavelengths are arranged in one CAN package. In the CAN package type optical transmission module, it is necessary to exchange voltage, current or electrical signals with an external power supply and control circuit via lead pins. Therefore, when multiple EML elements are arranged in the CAN package, the number of lead pins increases compared to the case where one EML element is arranged, which hinders the miniaturization of the module. Therefore, a structure is proposed in which the wiring used for exchanging with the power supply and the control signal is coaxially arranged on one lead pin to reduce the number of lead pins (see patent document 1).

[0004] Patent Document 1: International Publication No. 2018 / 211635

[0005] In the optical transmission module of the CAN package type for optical communication described in Patent Document 1, the number of lead pins is reduced, which can achieve miniaturization of the package. However, the GND of the lead pin is not the outermost part of the coaxial, so the GND wiring of the lead pin cannot be directly connected to the package. It is necessary to lead the GND wiring from the coaxial lead pin, which causes impedance deviation as a signal line, making the characteristics unstable. In addition, the lead pin is a multi-layer coaxial shape composed of an insulating layer and a conductive layer, so the manufacturing becomes cumbersome, which is the main reason for the cost increase. Summary of the invention

[0006] The present application discloses a technology for solving the above-mentioned problems, and aims to provide an optical transmission module having a plurality of semiconductor lasers built therein, which is easy to manufacture and can be miniaturized and has little impedance variation.

[0007] The optical transmitting module disclosed in the present application comprises: a plate-shaped metal core column, a block fixed on the core column, a sub-support fixed to the side of the block, a plurality of semiconductor lasers arranged on the sub-support, and a cap for fixing a lens and covering all components arranged on the core column. The optical transmitting module is constructed as follows: a plurality of lead pins, the same number as the plurality of semiconductor lasers, respectively penetrate a plurality of holes arranged on the core column, each of the plurality of lead pins is electrically connected to each of the plurality of semiconductor lasers, and a single-phase electrical signal that sets the core column to a ground potential is applied from an external power supply through each of the plurality of lead pins to each of the plurality of semiconductor lasers, so that the plurality of semiconductor lasers are modulated and oscillated.

[0008] According to the optical transmission module disclosed in the present application, it is possible to provide an optical transmission module which is easy to manufacture, can be miniaturized, has little impedance variation, and has a plurality of semiconductor lasers built therein. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a side view showing the internal structure of the optical transmission module according to the first embodiment.

[0010] Figure 2 This is a plan view showing the internal structure of the optical transmission module according to the first embodiment.

[0011] Figure 3 This is a side view showing the internal structure of another optical transmission module according to the first embodiment.

[0012] Figure 4 This is a plan view showing the internal structure of another optical transmission module according to the first embodiment.

[0013] Figure 5 This is a schematic configuration diagram for explaining a spot size converter of the optical transmission module according to the first embodiment.

[0014] Figure 6 This is a side view showing the internal structure of the optical transmission module according to the second embodiment.

[0015] Figure 7 It is a plan view showing the internal structure of the optical transmission module according to the second embodiment.

[0016] Figure 8 This is a side view showing the internal structure of another optical transmission module according to the second embodiment.

[0017] Fig. 9 This is a plan view showing the internal structure of another optical transmission module according to the second embodiment.

[0018] Fig.10 This is a side view showing the internal structure of the optical transmission module according to the third embodiment.

[0019] Fig.11 It is a plan view showing the internal structure of the optical transmission module according to the third embodiment.

[0020] Fig.12 This is a side view showing the internal structure of another optical transmission module according to the third embodiment.

[0021] Fig.13 This is a plan view showing the internal structure of another optical transmission module according to the third embodiment.

[0022] Fig.14 This is a side view showing the internal structure of the optical transmission module according to the fourth embodiment.

[0023] Fig.15 It is a plan view showing the internal structure of the optical transmission module according to the fourth embodiment.

[0024] Fig.16 This is a side view showing the internal structure of another optical transmission module according to the fourth embodiment.

[0025] Fig.17 This is a plan view showing the internal structure of another optical transmission module according to the fourth embodiment.

[0026] Fig.18 This is a side view showing the internal structure of the optical transmission module according to the fifth embodiment.

[0027] Fig.19 It is a plan view showing the internal structure of the optical transmission module according to the fifth embodiment.

[0028] Fig. 20 This is a line diagram showing the voltage waveform for driving two semiconductor lasers of the optical transmission module according to the sixth embodiment. DETAILED DESCRIPTION

[0029] Implementation method 1.

[0030] Figure 1 as well as Figure 2 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of the first embodiment. Figure 1 is a side view, Figure 2 It is a top view. A block 2 is fixed on a plate-shaped metal core column 1, and a sub-support 4 is installed on one side of the block 2. Two semiconductor lasers, a semiconductor laser 8a and a semiconductor laser 8b, are installed on the sub-support 4. Two photodiodes, a photodiode 9a and a photodiode 9b, are installed on the sub-support 5 installed on the core column 1. The photodiode 9a and the photodiode 9b are installed in a manner that the light receiving portion is located on the optical axis of the outgoing light from the rear end face of the semiconductor laser 8a and the semiconductor laser 8b, respectively, and are used for monitoring the output light of the semiconductor laser 8a and the semiconductor laser 8b, respectively.

[0031] Lead pins 3a and 3b are provided on the stem 1 for applying voltage to the semiconductor laser 8a and the semiconductor laser 8b from an external power source to flow a driving current for oscillation. In addition, lead pins 39a and 39b are provided on the photodiode 9a and the photodiode 9b for electrical connection to the outside, respectively. These lead pins are conductive pins made of an alloy mainly made of iron, nickel, copper, etc., plated with gold. Each lead pin protrudes from the stem 1 through the stem 1, and each lead pin is insulated from the stem 1 and fixed to the stem 1 by filling the gap between the stem 1 and each lead pin 3a, 3b, 39a, 39b with sealing materials 15a, 15b, 159a, 159b of insulating material, respectively.

[0032] Transmission substrate 6a and transmission substrate 6b are mounted on the side of block 2, and the front ends of lead pins 3a and lead pins 3b for semiconductor lasers are respectively bonded to pattern wiring 7a and pattern wiring 7b on transmission substrate 6a and transmission substrate 6b through conductive bonding materials 10a and 10b such as solder or conductive adhesive. The transmission substrate is composed of dielectric materials such as glass, aluminum oxide (Al2O3), aluminum nitride (AlN), etc. Pattern wiring 7a and pattern wiring 7b are electrically connected to semiconductor laser 8a and semiconductor laser 8b through wire 81a and wire 81b respectively. The thickness of the dielectric substrate, relative dielectric constant and pattern wiring are designed with characteristic impedance values ​​to suppress reflection of electrical signals.

[0033] Generally, circuits are often designed with line impedance of 50Ω. However, if the sealing material, lead pins, and the size of the hole of the core column are selected in consideration of the airtight sealing of the through-portion of the lead pin, it is difficult to set the characteristic impedance of the lead pin portion to 50Ω, and the characteristic impedance becomes about 25Ω. On the other hand, when the semiconductor laser is a DFB (Distributed Feedback) laser, the impedance is usually several Ω to several dozen Ω, so by using the lead pin of the above structure, impedance matching is easily achieved. In addition, compared with the structure of Patent Document 1, the ground potential is stable and the impedance deviation is reduced.

[0034] Photodiode 9a and lead pin 39a are electrically connected to each other by wires 91a and 91b, respectively. A GND pin (not shown) is provided on the back of stem 1 for electrically connecting stem 1 to a ground potential portion (GND) of an external circuit.

[0035] A cap 11 is mounted on the stem 1, and components such as the block 2, the sub-support 4, the sub-support 5, the transmission substrate 6a, the transmission substrate 6b, the semiconductor laser 8a, the semiconductor laser 8b, the photodiode 9a, the photodiode 9b are covered by the cap 11 and stored inside the cap 11. The emitted light of each semiconductor laser 8a and semiconductor laser 8b is focused to a point through a lens 12 provided in the opening of the cap 11, and is guided to an optical fiber 13. In addition, Figure 2 The top view of FIG. 1 is a top view showing the internal structure of the cap 11 in a state where the cap 11 to which the lens 12 is fixed is removed.

[0036] In the first embodiment, a single-phase electric signal based on GND is input from an external circuit to the lead pins 3a and 3b, and applied to the semiconductor lasers 8a and 8b, and the semiconductor lasers 8a and 8b oscillate and emit laser light in accordance with the respective electric signals. The laser light emitted from the front end faces of the semiconductor lasers 8a and 8b is focused by the lens 12 and guided to the optical fiber 13. On the other hand, the light emitted from the rear end faces of the semiconductor lasers 8a and 8b is received by the photodiodes 9a and 9b, respectively, so that the light output of the semiconductor lasers 8a and 8b can be monitored respectively.

[0037] In addition, Figure 1 , Figure 2 In the structure shown, there is a structure in which two semiconductor lasers are arranged on one side of the block, but it is not limited to two. It can also be constructed so that more semiconductor lasers are arranged on one side of the block, and a plurality of lead pins corresponding to the number of semiconductor lasers are provided on the core column, and a single-phase electrical signal is applied to each semiconductor laser from each lead pin.

[0038] Here, if Figure 1 as well as Figure 2 As shown, when two semiconductor lasers, semiconductor laser 8a and semiconductor laser 8b, are arranged, the arrangement from lead pin 3a to semiconductor laser 8a and the arrangement from lead pin 3b to semiconductor laser 8b can be arranged in line symmetry when viewed from a direction perpendicular to the side surface of sub-support 4 etc. on which block 2 is mounted. By making such a line symmetric arrangement, the impedance from lead pin 3a to semiconductor laser 8a and the impedance from lead pin 3b to semiconductor laser 8b can be made equal.

[0039] Figure 3 as well as Figure 4 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of another structure of the first embodiment. Figure 3 is a side view, Figure 4 is a top view. Figure 3 as well as Figure 4 In the optical transmission module shown in FIG. 1 , the semiconductor laser 80a and the semiconductor laser 80b have a spot size converter (SSC) 23a and a spot size converter 23b on the front end face side, respectively. The spot size converter 23a is, for example, Figure 5 As shown, this can be achieved by providing a tapered structure 19a at the front end of the laser diode region 18a of the semiconductor laser 80a. Figure 5 The light spot size converter of the tapered structure 19a shown in the figure narrows the spread angle of the light emitted from the front end face 16a of the semiconductor laser 80a. The semiconductor laser 80b also has the same structure, which can improve the coupling efficiency of the output light from the two semiconductor lasers 80a and the semiconductor laser 80b to the optical fiber 13, or can relax the position accuracy during installation.

[0040] The semiconductor laser disclosed in each embodiment of the present application is not a laser modulated by a modulator after emitting laser light like an EML, but a semiconductor laser modulated by controlling the current itself used for laser oscillation. For example, it is a semiconductor laser modulated by directly controlling the current driving a DFB (Distributed Feedback) laser. Generally, in a structure in which the driving current of a semiconductor laser is directly controlled for modulation, voltages with positive and negative potentials relative to the ground potential are applied to the positive electrode and the negative electrode for causing the current to flow in the semiconductor laser, that is, a differential signal is applied for driving. In such a structure, in order to drive the semiconductor laser, two electrical connections on the positive side and the negative side are required relative to the ground potential of the core column, and two lead pins are required for one semiconductor laser in order to make an electrical connection from the outside of the core column. On the other hand, in the present application, since a single-phase electrical signal with only a positive or negative potential relative to the ground potential is applied to the semiconductor laser, only one lead pin is required for driving one semiconductor laser, and the number of lead pins required is small. In addition, compared with a structure such as an EML that requires an electrical connection for driving a semiconductor laser and an electrical connection for applying an electrical signal for modulation, the number of lead pins required for external electrical connection with the stem 1 is small. Therefore, the semiconductor laser and driving method using this structure are suitable for miniaturization of an optical transmission module that integrates multiple semiconductor lasers.

[0041] As described above, in the optical transmission module of the first embodiment, each semiconductor laser is driven by a single-phase electrical signal (a signal having only a positive or negative voltage) from each lead pin with reference to the ground potential of the stem 1. That is, a structure is formed in which the oscillation waveform of each semiconductor laser is modulated by applying a single-phase electrical signal to each semiconductor laser and controlling the current used to oscillate each semiconductor laser. According to such a structure, by integrating a plurality of semiconductor lasers having different laser wavelengths and applying a single-phase signal with different phases to each semiconductor laser, the optical output of each semiconductor laser is synthesized by the optical fiber 13, thereby making it possible to multiply the bit rate compared with the optical transmission module with only one semiconductor laser installed. In addition, in the structure in which two semiconductor lasers are arranged, the arrangement from one lead pin to one semiconductor laser and the arrangement from another lead pin to another semiconductor laser are arranged in a line-symmetrical manner when viewed from a direction perpendicular to the side of the semiconductor laser installed with the block 2, thereby making it possible to make the impedance from the lead pin to the semiconductor laser equal. In this configuration, two semiconductor lasers having the same oscillation wavelength are driven by single-phase signals of the same phase, that is, the same voltage waveform, so that the oscillation waveforms become the same, thereby being able to extract laser light with twice the output of the wavelength.

[0042] Implementation method 2.

[0043] Figure 6 as well as Figure 7 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of the second embodiment. Figure 6 is a side view, Figure 7It is a top view. In the optical transmission module of the second embodiment, as in the first embodiment, a block 2 is mounted on the stem 1, and a sub-support 4 is mounted on the side of the block 2. A semiconductor integrated component 20 is mounted on the sub-support 4, and the semiconductor integrated component 20 is an integrated component of two semiconductor lasers 8a, semiconductor laser 8b, and two photodiodes 9a and photodiode 9b. An optical combiner 21, an optical waveguide 22a, and an optical waveguide 22b are provided on the semiconductor integrated component 20. The outgoing light from the front end faces of the two semiconductor lasers 8a and semiconductor laser 8b is input to the optical combiner 21 through the optical waveguide 22a and the optical waveguide 22b, respectively, and after being combined in the optical combiner 21, it is emitted from the front end face of the semiconductor integrated component 20. The outgoing light from the rear end faces of the two semiconductor lasers 8a and semiconductor laser 8b is received by the photodiode 9a and the photodiode 9b through the optical waveguide 220a and the optical waveguide 220b, respectively. Electrode pads for supplying power to semiconductor lasers 8a, 8b and photodiodes 9a, 9b are provided on semiconductor integrated device 20. Electrode pads are electrically connected to lead pins 3a, 3b, 39a, 39b through wires.

[0044] In the first embodiment, the light emitted from the rear end face of the semiconductor laser 8a and the semiconductor laser 8b propagates in space and is received by the photodiode 9a and the photodiode 9b. In such a structure, light crosstalk occurs between adjacent lines and the light output of the emitted light of each semiconductor laser cannot be accurately monitored by the respective photodiodes. In the second embodiment, the semiconductor laser 8a, the semiconductor laser 8b, the photodiode 9a and the photodiode 9b are integrated into a semiconductor integrated element 20, and the emitted light from the rear end face of each semiconductor laser 8a and the semiconductor laser 8b is respectively enclosed in the optical waveguide 220a and the optical waveguide 220b for transmission, thereby avoiding crosstalk between adjacent channels.

[0045] In addition, the structure is as follows: the outgoing light from the front end faces of the two semiconductor lasers 8a and 8b is input to the optical combiner 21 through the optical waveguide 22a and the optical waveguide 22b respectively, and after being combined in the optical combiner 21, it becomes a laser beam and is emitted toward the lens 12 and incident on the optical fiber 13. In the first embodiment, it is necessary to guide the two laser beams to the incident end of one optical fiber through the lens, and it is necessary to adjust the positions of the two laser beams to be consistent, but according to the second embodiment, since this adjustment is not required, it is possible to obtain an optical transmission module that is easy to manufacture.

[0046] Figure 8 as well as Fig. 9 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of another structure of the second embodiment. Figure 8 is a side view, Fig. 9 is a top view. Figure 8 as well as Fig. 9 In the optical transmission module shown in the figure, Figure 5 The spot size converter 230 for enlarging the spot size of the laser light similarly to the spot size converter described in the above is provided on the exit surface of the optical waveguide for extracting the exit light of the optical combiner 21. As a result, the spread angle of the light emitted from the spot size converter 230 is narrowed, and the coupling efficiency to the optical fiber 13 can be improved, or the position accuracy during installation can be relaxed.

[0047] Implementation method 3.

[0048] Fig.10 as well as Fig.11 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of the third embodiment. Fig.10 is a side view, Fig.11 1 is a top view. In the third embodiment, similar to the first embodiment, a stem 1, a block 2, a transmission substrate 6a, a transmission substrate 6b, a sub-support 4, a sub-support 5, a lead pin 3a, a lead pin 3b, a cap 11, and a lens 12 are provided. A semiconductor integrated element 20 in which two semiconductor lasers 8a and 8b, two photodiodes 9a and 9b are integrated is mounted on the sub-support 4. Unlike the second embodiment, the semiconductor integrated element 20 does not integrate an optical combiner. Light emitted from the front end faces of the two semiconductor lasers 8a and 8b is transmitted in the optical waveguide 22a and the optical waveguide 22b, respectively, emitted from the front end face of the semiconductor integrated element 20, and is respectively focused at the incident end of the optical fiber 13 by the lens 12. Although a loss caused by the optical combiner 21 is generated in the second embodiment, a loss caused by the optical combiner is not generated in the third embodiment, and the power of the light emitted from the front end face of the semiconductor integrated element 20 can be improved compared with the optical transmission module of the second embodiment.

[0049] Fig.12 as well as Fig.13 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of another structure of the third embodiment. Fig.12 is a side view, Fig.13 is a top view. Fig.12 as well as Fig.13 In the optical transmission module shown, a spot size converter 230a and a spot size converter 230b are provided at the front ends of the optical waveguide 22a and the optical waveguide 22b, respectively, which emit light from the front end surface of the semiconductor integrated element 20. As a result, the spread angle of the light emitted from the spot size converter becomes narrower, and the coupling efficiency to the optical fiber 13 can be improved or the position accuracy during installation can be relaxed.

[0050] Implementation method 4.

[0051] Fig.14 as well as Fig.15 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of the fourth embodiment. Fig.14 is a side view, Fig.15 : is a top view. In Embodiment 4, a semiconductor integrated element 20a in which a semiconductor laser 8a and a photodiode 9a are integrated, and a semiconductor integrated element 20b in which a semiconductor laser 8b and a photodiode 9b are integrated are adjacently mounted on a sub-support 4, and the sub-support 4 is mounted on one side of the block 2. The outgoing light emitted from the front end faces of the semiconductor laser 8a and the semiconductor laser 8b is transmitted in the optical waveguide 22a and the optical waveguide 22b respectively integrated in the semiconductor integrated element 20a and the semiconductor integrated element 20b, and is emitted from the front end faces of the semiconductor integrated element 20a and the semiconductor integrated element 20b. The outgoing light emitted from the rear end faces of the semiconductor laser 8a and the semiconductor laser 8b is transmitted in the optical waveguide 220a and the optical waveguide 220b respectively, and is received by the photodiode 9a and the photodiode 9b respectively.

[0052] In the third embodiment, the manufacturing yield of the semiconductor integrated element is the product of the respective manufacturing yields of the two semiconductor lasers and the two photodiodes. In contrast, in the fourth embodiment, the product is a semiconductor laser and a photodiode, thereby alleviating the influence of the manufacturing yields of the semiconductor laser and the photodiode, and improving the manufacturing yield of the semiconductor integrated element.

[0053] Fig.16 as well as Fig.17 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of another structure of the fourth embodiment. Fig.16 is a side view, Fig.17 is a top view. Fig.16 as well as Fig.17 In the optical transmission module shown, a light spot size converter 230a and a light spot size converter 230b are provided at the front ends of the optical waveguides 22a and 22b, respectively, from which light is emitted from the front end faces of the semiconductor integrated device 20a and the semiconductor integrated device 20b, respectively. As a result, the spread angle of the light emitted from the light spot size converter becomes narrower, and the coupling efficiency to the optical fiber 13 can be improved or the position accuracy during installation can be relaxed.

[0054] Implementation method 5.

[0055] Fig.18 as well as Fig.19 1 is a schematic diagram showing the internal structure of the cap 11 of the optical transmission module of Embodiment 5. Fig.18 is a side view, Fig.19is a top view. In the first to fourth embodiments, a plurality of semiconductor lasers are mounted only on one side of the block 2 fixed to the stem 1. On the other hand, in the optical transmission module of the fifth embodiment, a plurality of semiconductor lasers are mounted on one side of the block 2 fixed to the stem 1 and on the other side opposite to the one side. That is, on one side, Figure 1 , Figure 2 The optical transmission module shown is similarly equipped with a sub-support 4ab, on which two semiconductor lasers 8a and 8b are mounted. In addition, two photodiodes 9a and 9b are mounted on a sub-support 5ab mounted on the stem 1. In addition, lead pins 3a and 3b for semiconductor lasers and lead pins 39a and 39b for photodiodes are passed through the stem 1. The side surface opposite to the one side surface, that is, the other side surface, also has the same structure as the one side surface. That is, a sub-support 4cd is mounted on the other side surface, on which two semiconductor lasers 8c and 8d are mounted. In addition, two photodiodes 9c and 9d are mounted on a sub-support 5cd mounted on the stem 1, and the two photodiodes 9c and 9d respectively detect the lasers output from the rear end faces of the semiconductor laser 8c and the semiconductor laser 8d. Furthermore, the lead pins 3c and 3d for the semiconductor laser and the lead pins 39c and 39d for the photodiode penetrate the stem 1. According to this structure, the bit rate can be further increased to twice that of the structures of the first to fourth embodiments.

[0056] Fig.18 as well as Fig.19 The case where the structure of the optical transmission module with two semiconductor lasers shown in Embodiment 1 is applied to an optical transmission module with four semiconductor lasers is shown. Of course, the structure of the optical transmission module with two semiconductor lasers shown in Embodiments 2 to 4 can also be applied to an optical transmission module with four semiconductor lasers. In such a structure, the bit rate can also be increased to 2 times.

[0057] Implementation method 6.

[0058] Fig. 20 FIG. 1 is a line diagram showing a driving waveform of a semiconductor laser of an optical transmission module according to Embodiment 6. Figure 1 , Figure 2 In the optical transmission module of the structure shown in FIG. 1 , semiconductor laser 8a and semiconductor laser 8b are formed by semiconductor lasers having opposite polarities. That is, if semiconductor laser 8a is a p-type semiconductor laser, semiconductor laser 8b is set to an n-type semiconductor laser. Fig. 20The voltage waveforms represented by V8a and V8b are relative to the ground potential (at Fig. 20 The potential represented by 0 in the figure) is a voltage waveform having a differential relationship with each other.

[0059] Alternatively, the semiconductor laser 8a and the semiconductor laser 8b are installed in such a manner that the polarities are the same and the electrical wiring of the input electrical signal and the ground potential are opposite to each other. Figure 1 , Figure 2 In the structure shown, semiconductor lasers 8a and 8b of the same polarity are mounted in such a manner that the cathode of semiconductor laser 8a is connected to the ground pattern of sub-support 4, and the anode of semiconductor laser 8b is connected to the ground pattern of sub-support 4. Furthermore, wire 81a is connected to the anode of semiconductor laser 8a, and wire 81b is connected to the cathode of semiconductor laser 8b. Fig. 20 The voltage waveforms represented by V8a and V8b are relative to the ground potential (at Fig. 20 The potential represented by 0 in the figure) is a voltage waveform having a differential relationship with each other.

[0060] According to the above configuration, if the oscillation wavelengths of the semiconductor laser 8a and the semiconductor laser 8b are the same, the output of the laser light output from the optical transmission module can be doubled.

[0061] Although various illustrative embodiments and examples are described in this application, 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 the embodiment alone or in various combinations. Therefore, countless unillustrated variations can be imagined within the scope of the technology disclosed in the specification of this application. For example, it includes the case where at least one constituent element is deformed, added or omitted, and also includes the case where at least one constituent element is extracted and combined with constituent elements of other embodiments.

[0062] Description of Reference Numerals

[0063] 1...core column; 2...block; 3a, 3b, 3c, 3d, 39a, 39b, 39c, 39d...lead pin; 4, 4ab, 4cd, 5, 5ab, 5cd...sub-support; 8a, 8b, 8c, 8d, 80a, 80b...semiconductor laser; 9a, 9b, 9c, 9d...photodiode; 11...cap; 12...lens; 21...optical combiner; 22a, 22b, 220a, 220b...optical waveguide; 23a, 23b, 230, 230a, 230b...spot size converter.

Claims

1. An optical transmission module, comprising: a plate-shaped metal stem, a block fixed to the stem, a sub-support fixed to the side of the block, a plurality of semiconductor lasers provided on the sub-support, and a cap for fixing a lens and covering all components arranged on the stem, characterized in that: The optical transmitting module is constructed as follows: a plurality of lead pins having the same number as the plurality of semiconductor lasers respectively penetrate through a plurality of holes provided in the core column, each of the plurality of lead pins is electrically connected to each of the plurality of semiconductor lasers, a single-phase electrical signal for setting the core column to a ground potential is applied from an external power source through each of the plurality of lead pins to each of the plurality of semiconductor lasers, and the plurality of semiconductor lasers are modulated and oscillated by directly controlling the driving current.

2. The optical transmission module according to claim 1, characterized in that: The number of the plurality of semiconductor lasers arranged on the side surface of the block is two, and the arrangement from one lead pin to one semiconductor laser and the arrangement from another lead pin to another semiconductor laser are line-symmetrical when viewed from a direction perpendicular to the side surface of the block.

3. The optical transmission module according to claim 1 or 2, characterized in that: The same number of photodiodes as the number of the plurality of semiconductor lasers are provided, and the photodiodes detect laser light from the rear end facet of each of the plurality of semiconductor lasers.

4. The optical transmission module according to claim 1 or 2, characterized in that: The oscillation wavelengths of the plurality of semiconductor lasers are all different.

5. The optical transmission module according to claim 1 or 2, characterized in that: The oscillation wavelengths of the plurality of semiconductor lasers are all the same, and a single-phase electrical signal having the same phase is applied to each semiconductor laser.

6. The optical transmission module according to claim 1 or 2, characterized in that: The plurality of semiconductor lasers include a spot size converter for enlarging the spot size of laser light on the front end face side of each of the semiconductor lasers.

7. The optical transmission module according to claim 1 or 2, characterized in that: The plurality of optical waveguides are provided, the number of which is the same as that of the plurality of semiconductor lasers, and the plurality of optical waveguides guide the laser beams outputted from the front end faces of the plurality of semiconductor lasers.

8. The optical transmission module according to claim 7, characterized in that: A spot size converter for enlarging the spot size of the laser light is provided on the output side of each of the plurality of optical waveguides.

9. The optical transmission module according to claim 7, characterized in that: An optical combiner is provided, and the laser beams from the plurality of optical waveguides are coupled to the optical combiner.

10. The optical transmission module according to claim 9, characterized in that: A spot size converter for enlarging the spot size of the laser light is provided on the output side of the optical multiplexer.

11. The optical transmission module according to claim 1, characterized in that: Sub supports are fixed to one side surface of the block and another side surface opposite to the side surface, respectively, and a plurality of semiconductor lasers are arranged on each of the sub supports.

12. The optical transmission module according to claim 2, characterized in that: The two semiconductor lasers are semiconductor lasers having opposite polarities to each other, and the single-phase electric signals applied to the two semiconductor lasers are voltage signals having a differential relationship with respect to the ground potential.

13. The optical transmission module according to claim 2, characterized in that: The two semiconductor lasers are semiconductor lasers of the same polarity, and the single-phase electric signals applied to the two semiconductor lasers are voltage signals having a differential relationship with respect to the ground potential.

14. The optical transmission module according to claim 12 or 13, characterized in that: The oscillation wavelengths of the two semiconductor lasers are the same wavelength.

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