JP2016099508A - Method for manufacturing optical transceiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical transceiver capable of efficiently arranging components inside.SOLUTION: The method for manufacturing the optical transceiver includes a first step of assembling a modulator unit U1 including a modulator, a power supply substrate, and a GPO cable, a second step of mounting a wavelength variable light source 13 and a control substrate on an upper housing 2, a third step of mounting the modulator unit U1 on the upper housing 2, a fourth step of mounting a light-receiving unit on a main substrate 7, a fifth step of mounting the main substrate 7 on the upper housing 2, a sixth step of mounting a polarization holding coupler 14 on the main substrate 7, a seventh step of connecting a light source unit U2 and the polarization holding coupler 14, an eighth step of connecting the polarization holding coupler 14 and the modulator, a ninth step of connecting the polarization holding coupler 14 and the light-receiving unit, and a tenth step of connecting the modulator, a receptacle 18, and the light-receiving unit.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing an optical transceiver.

  Patent Document 1 describes an optical module including a wavelength tunable semiconductor laser and a semiconductor optical modulator. In this optical module, the semiconductor optical modulator modulates light output from the wavelength tunable semiconductor laser. This optical module includes a light extraction port for extracting light output from the semiconductor optical modulator. The light output direction from the wavelength tunable semiconductor laser and the light input direction to the semiconductor optical modulator are opposite to each other. Further, as viewed from the light extraction port, the wavelength tunable semiconductor laser and the semiconductor optical modulator are arranged in parallel.

  In the optical module, efforts are made to increase the total transmission capacity by using both amplitude modulation and other modulation methods. Examples of the other modulation methods include polarization mode modulation, phase modulation, or modulation in which polarization (polarization modulation), phase (phase modulation), and amplitude are combined with each other. This modulation method in which polarization, phase, and amplitude are combined with each other is known as a transmission mode based on a so-called coherent method. In the coherent method, light phase information is used for transmission. Also, a state of 1 or 0 is created and detected for the signal intensity of the 0 ° component and 90 ° component in the phase difference from the local oscillation signal, respectively, and this creation and detection is performed for the polarization components of 0 ° and 90 °. By doing so, a transmission capacity of 4 times is secured. This method is called DP-QPSK (Dual Polarization Quadrature Phase Shift Keying).

  In a coherent transceiver using the DP-QPSK system, a Tx side light source (4 channels of DC light), a multi-channel optical modulator, and an ICR (Integrated Coherent Receiver) side of 4 channels are provided inside the housing. A receiver, a local light source, and a signal processing IC must be mounted.

JP 2009-146992 A

  In the coherent transceiver as described above, the number of components to be mounted is increased in each stage due to the fact that it is multi-channel and phase signal processing is required as compared with a single channel full duplex optical transceiver. . Further, when the coherent optical transceiver also has a polarization multiplexing function, a polarization processing optical circuit is also required, and the number of parts is further increased. Accordingly, a large number of optical components and electronic components must be mounted in one housing, and the component mounting density increases. Therefore, it is necessary to construct an assembly procedure for efficiently arranging the components inside.

  It is an object of the present invention to provide a method for manufacturing an optical transceiver capable of efficiently arranging components therein.

  An optical transceiver according to an aspect of the present invention is a method for manufacturing a coherent optical transceiver in which a modulator, a wavelength tunable light source, an optical receiving unit, and a polarization maintaining coupler are mounted in a housing, and the modulator and the modulator are biased. A first substrate for mounting a circuit for providing a circuit, a modulator unit including a cable for outputting a drive signal to the modulator, a wavelength tunable light source, and a circuit for determining the wavelength of the wavelength tunable light source. A second step of mounting the light source unit including the second substrate on the housing, a third step of mounting the modulator unit on the housing, and a fourth step of mounting the light receiving unit on one surface of the third substrate; A fifth step of mounting the third substrate on which the optical receiving unit is mounted on the housing such that the other surface of the third substrate is exposed, and a polarization maintaining coupler on the other side of the third substrate. A sixth step of mounting on the surface, a seventh step of connecting the light source unit and the polarization maintaining coupler by the first polarization maintaining connector and the first polarization maintaining fiber, and the polarization maintaining coupler and the modulator, The eighth step of connecting the second polarization maintaining connector and the second polarization maintaining fiber, and the ninth step of connecting the polarization maintaining coupler and the optical receiving unit using the third polarization maintaining connector and the third polarization maintaining fiber. And a tenth step of connecting the modulator and the receptacle mounted on the housing by the first single mode fiber, and connecting the receptacle and the optical receiving unit by the second single mode fiber. The process, the eighth process, and the ninth process are performed in any order.

  In one embodiment of the present invention, components can be efficiently arranged inside.

It is a perspective view which shows the optical transceiver which concerns on embodiment. It is a perspective view which shows the state which removed the upper housing from the optical transceiver of FIG. It is a perspective view which shows the state which removed the lower housing from the optical transceiver of FIG. It is the figure which showed typically the optical wiring in the optical transceiver of FIG. It is a perspective view which shows each component which comprises a modulator unit. It is a perspective view which shows each component which comprises a modulator unit. It is a perspective view which shows each component which comprises a light source unit. It is a perspective view which shows the state in which the modulator unit was mounted in the upper housing. It is a perspective view which shows one surface of a main board | substrate. It is a perspective view which shows the other surface of a main board | substrate. It is a perspective view which shows an optical receiver unit and a main board | substrate. It is a rear view which shows an optical receiver unit. It is a perspective view which shows the state which mounted the main board | substrate in the upper housing. It is a perspective view which shows the state which mounted the polarization maintaining coupler and the internal fiber on the main board | substrate of FIG. It is a figure which shows typically the wiring state of an internal fiber. It is a perspective view which shows a lower housing and a sealing member.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an optical transceiver manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing an appearance of an optical transceiver 1 according to the present embodiment. The optical transceiver 1 is a coherent transceiver that conforms to the CFP standard. The optical transceiver 1 includes an upper housing (housing) 2, a lower housing (housing) 3, two screws 4, and a front panel 5. Hereinafter, the terms “front-rear direction”, “up-down direction”, and “left-right direction” are used in the drawings, but these terms are for convenience based on the illustrated state. In the following description, the upper direction is the direction in which the upper housing 2 is provided when viewed from the lower housing 3, the front direction is the direction in which the front panel 5 is provided as viewed from the upper housing 2 and the lower housing 3, and the left-right direction is This is the direction in which the two screws 4 are juxtaposed (the width direction of the optical transceiver 1).

  The upper housing 2 and the lower housing 3 are made of metal (made of metal die cast). The length in the front-rear direction of the upper housing 2 and the lower housing 3 is about 15 cm, the width in the left-right direction of the upper housing 2 and the lower housing 3 is about 8 cm, and the height in the vertical direction of the upper housing 2 and the lower housing 3 is about 1. 5 cm. All the parts of the optical transceiver 1 are accommodated in the internal space formed by the upper housing 2 and the lower housing 3. Two screws 4 protrude forward from the front panel 5 at both lateral portions of the front panel 5. The screw 4 is used to attach the optical transceiver 1 to an external host system cage.

  As described above, all the components are mounted in the internal space formed by the upper housing 2 and the lower housing 3 with almost no gap. Therefore, if the assembly procedure (mounting procedure) is mistaken, a situation may occur in which the optical transceiver 1 is not assembled.

  Further, in the CFP standard, only one type of 3.3 V is defined as a power source supplied from the host system to the optical transceiver. Therefore, when there are many mounted parts as described above, the power supply required inside the optical transceiver cannot be covered by one type of 3.3V, and it is boosted and lowered from 3.3V by a DC / DC converter. The required power supply must be generated. When the above DC / DC converter, particularly a step-up DC / DC converter is used, the number of electronic components increases. For this reason, not only the circuit board becomes large, but another board must be prepared and a power source for the components must be generated each time. That is, it is necessary to prepare a procedure for mounting a plurality of substrates and an FPC for connecting the plurality of substrates in the optical transceiver.

  In coherent communication, a demodulator that handles a phase signal is required on the receiving side. In general, the function as a demodulator is a DSP (Digital Signal Processor). The DSP can handle multiple channels simultaneously and digitally, and the DSP processing speed may exceed 10 Gbps and reach 25 Gbps. A DSP that performs complex digital processing at such a high speed may have power consumption exceeding 30 W. The DSP is a kind of high-performance CPU, and the DSP cannot be expected to operate normally unless attention is paid to its heat dissipation.

  Further, in order to connect a large number of optical components to each other in the optical transceiver, a large number of internal fibers are required. Furthermore, in an optical transceiver having a polarization multiplexing function, it is also necessary to optically connect components while maintaining the polarization direction of light. In the method for manufacturing the optical transceiver 1 according to the present embodiment, the component arrangement that avoids the above problems is realized. Hereinafter, the component arrangement of the optical transceiver 1 will be described.

  FIG. 2 is a perspective view showing the arrangement of components in the optical transceiver 1. FIG. 3 is a perspective view showing a state in which the upper housing 2 is removed from the lower housing 3. As shown in FIGS. 2 and 3, the screw 4 passes through the inside of the upper housing 2 and the lower housing 3, and is placed in a recess 3 e formed in the lower housing 3.

  The rear end portion 4 a of the screw 4 protrudes rearward on both sides of the electric plug 6 located at the rear end of the optical transceiver 1. The electric plug 6 is provided with signal pins and power supply pins, and a total of 148 pins are arranged. The pitch of each pin is 0.8 mm. The 148 pins are electrically connected to the electrodes of the electrical connector prepared in the host system by engaging the two screws 4 with holes formed in the housing of the host system.

  In the internal space of the optical transceiver 1 surrounded by the upper housing 2 and the lower housing 3, two drivers 11 that output electrical signals, a modulator 12, a wavelength variable light source 13, and a polarization maintaining coupler (PMC: Polarization Maintaining Coupler) 14, ICR 15, DSP 16, GPO cable 17, and receptacle 18 are mounted.

  In the internal space of the optical transceiver 1, the modulator 12 extends in the front-rear direction (long axis direction) of the optical transceiver 1 on the side of the driver 11. The modulator 12 and the driver 11 are connected via four GPO cables 17. Further, seven internal fibers F1 to F7 are arranged inside the optical transceiver 1. The arrangement mode of the internal fibers F1 to F7 will be described in detail later. The internal fibers F1 to F7 are provided to optically connect the modulator 12, the variable wavelength light source 13, the polarization maintaining coupler 14, the ICR 15 and the receptacle 18.

  The modulator 12 is connected to the receptacle 18 via an internal fiber F6 (first single mode fiber) that extends forward from the modulator 12 and is folded back. The four optical signals modulated by the modulator 12 are output from the optical connector C1 (see FIG. 1) multiplexed in the modulator 12 and received in the receptacle 18. On the other hand, input signal light is input from the optical connector C2.

  The receptacle 18 is a component exposed forward from the front panel 5. The receptacle 18 is connected to the ICR 15 via an internal fiber F7 (second single mode fiber) that extends rearward from the receptacle 18 and goes around the inside of the housing. The input signal light input from the optical connector C2 is input to the ICR 15 via the internal fiber F7. The internal fibers F6 and F7 are both single mode fibers.

  The wavelength variable light source 13 includes a wavelength variable laser (LD) and functions as a light source that emits local light. The light source unit U2 including the wavelength tunable light source 13 is disposed through the opening 5a of the front panel 5. The polarization maintaining coupler 14 extends in the front-rear direction behind the receptacle 18 and on the side of the ICR 15. The ICR 15 is provided on the side opposite to the modulator 12 with respect to the driver 11. The DSP 16 is located behind the ICR 15. The receptacle 18 passes through the opening 5a, exposes the opening from the front panel of the optical transceiver 1, and the optical connectors C1 and C2 are inserted into the opening. Full-duplex communication is realized by inserting and engaging the optical connectors C1 and C2 into the receptacle 18.

  FIG. 4 is a diagram schematically showing the optical wiring in the optical transceiver 1. It is necessary to dispose a polarization maintaining fiber on the path from the wavelength variable light source 13 to the modulator 12 via the polarization maintaining coupler 14 and the path from the polarization maintaining coupler 14 to the ICR 15. That is, with respect to the modulator 12, the variable wavelength light source 13, and the ICR 15, the polarization direction of the light must be maintained with respect to the input light and the output light, and the polarization maintaining fiber is drawn out from these optical components in the so-called pigtail form. . When a normal optical connector is adopted for the fiber lead-out structure, the polarization direction of light cannot be maintained due to the rotation of the optical connector at the connection portion of the optical connector.

  The coherent optical transceiver 1 includes four components (wavelength variable light source 13, polarization maintaining coupler 14, modulator 12 and ICR 15) related to the polarization maintaining fiber, and these components are connected via the polarization maintaining fiber. In the case of connection, fusion connection is generally used as a connection means between components. However, in the case of fusion splicing, in order to maintain the strength of the connecting portion, several centimeters or more before and after the connecting portion must be fixed with reinforcing parts, and the internal fibers F1 to F7 are placed in a very limited space. In the optical transceiver 1 to be arranged, it is difficult to adopt this fusion splicing. In the optical transceiver 1, instead of the fusion splicing, a connection using the polarization maintaining connectors P1 to P3 is used. The polarization maintaining connectors P1, P2, and P3 include male connectors P11, P21, and P31 and female connectors P12, P22, and P32, respectively.

  An internal fiber F1 (first polarization maintaining fiber) that is a polarization maintaining fiber extracted from the wavelength variable light source 13 is extracted from the polarization maintaining coupler 14 by a polarization maintaining connector P1 (first polarization maintaining connector). It couple | bonds with the internal fiber F2 (1st polarization maintaining fiber) which is the polarization maintaining fiber. An internal fiber F3 (second polarization maintaining fiber), which is a polarization maintaining fiber drawn from the polarization maintaining coupler 14, is drawn from the modulator 12 by the polarization maintaining connector P2 (second polarization maintaining connector). It couple | bonds with the internal fiber F4 (2nd polarization maintaining fiber) which is a polarization maintaining fiber.

  An internal fiber F5 (third polarization maintaining fiber), which is a polarization maintaining fiber drawn from the polarization maintaining coupler 14, is coupled to the ICR 15 via the polarization maintaining connector P3 (third polarization maintaining connector). Here, since the polarization maintaining connector P3 is integrated with the ICR 15, the internal fiber F5 is directly engaged with the ICR 15. The ICR 15 is provided with an optical connector C3 (see FIG. 2), and the ICR 15 and the receptacle 18 are connected by the optical connector C3 and the internal fiber F7 described above.

  The local light output from the wavelength variable light source 13 is separated by the polarization maintaining coupler 14 while maintaining the polarization direction. One local light separated by the polarization maintaining coupler 14 is input to the modulator 12 and the other local light is input to the ICR 15. The modulator 12 modulates the local light input from the wavelength tunable light source 13 via the polarization maintaining coupler 14 according to the electrical signal provided from the driver 11 via the GPO cable 17. The four GPO cables 17 correspond to the electric signals QX, QY, IX, and IY, respectively, and the electric signals QX, QY, IX, and IY respectively correspond to the real part I and the imaginary part Q of each polarization, X, and Y. Corresponding signal. The branching ratio of the polarization maintaining coupler 14 is set to 7: 3 in the present embodiment on the modulator 12 side and the ICR 15 side, but this branching ratio can be changed as appropriate.

  Next, a manufacturing method (assembly method) of the optical transceiver 1 will be described. The method for manufacturing the optical transceiver 1 includes first to tenth steps to be described later. First, the first step, which is a step of assembling the modulator unit U1 including the modulator 12, will be described.

  In the first step, the modulator unit U1 is assembled outside the housing of the optical transceiver 1. FIG. 5 is an exploded perspective view showing components constituting the modulator unit U1. As shown in FIG. 5, the modulator unit U <b> 1 is connected to the above-described modulator 12, a power supply board (first board) 21 on which a circuit for supplying power to the modulator 12 is mounted, and the power supply board 21. A first FPC 22 and a second FPC 23, a shield member 24, and a spacer 25 are provided.

  The power supply board 21 is a sub board on which a power supply circuit is mounted. The power supply circuit includes a circuit that applies a bias to the modulator 12. In the first step, first, the first FPC 22 is soldered to the power supply substrate 21. The first FPC 22 is an FPC connected to a main board 7 (third board) described later. Further, the second FPC 23 for connecting to the power supply substrate 21 is soldered to the DC bias pin 12 a exposed on the side surface 12 c of the modulator 12.

  FIG. 6 is an enlarged view of main parts of the modulator 12, the power supply substrate 21, the second FPC 23, and the spacer 25. On the back surface 21 a of the power supply substrate 21, a ground pattern is formed on substantially the entire surface except for the pads 21 b connected to the second FPC 23. Soldering between the DC bias pin 12a of the modulator 12 and the second FPC 23 is performed in a state where the second FPC 23 is not bent. In this state, soldering between the second FPC 23 and the pad 21b is also performed.

  After the second FPC 23 is soldered to the DC bias pin 12 a of the modulator 12, one surface 23 a of the second FPC 23 is soldered to the pad 21 b of the power supply substrate 21 as shown in FIGS. 5 and 6. Thus, the modulator 12 and the power supply substrate 21 are integrated through the second FPC 23. At this time, the power supply substrate 21 is developed in a direction perpendicular to the DC bias pin 12 a of the modulator 12.

  Next, the conductive spacer 25 is placed on the one side surface 12b of the modulator 12, and in this state, the second FPC 23 is bent at a substantially right angle as shown in FIG. The second FPC 23 is bent at a location separated from the one side surface 12 b by the thickness of the spacer 25. The spacer 25 has a U shape, and the pad 21b of the power supply substrate 21 is located at a central portion 25a surrounded by each side of the U shape.

  Since the pad 21b is separated from the one side surface 12b by the thickness of the spacer 25, even if the housing of the modulator 12 is made of metal, the pad 21b does not short-circuit with the metal housing of the modulator 12. . Further, by bending the second FPC 23 at a substantially right angle, the power supply substrate 21 is developed in parallel to the DC bias pin 12a of the modulator 12 (state shown in FIG. 5). Then, the power supply substrate 21 is screwed to the modulator 12 together with the spacer 25. There are, for example, two places for screwing.

  Next, the shield member 24 is attached to the modulator 12. The shield member 24 is formed by performing only a cutting process and a bending process on a single metal plate. The cross-sectional shape of the shield member 24 is a horizontally long U-shape, and the power supply substrate 21 is inserted into a central portion (an opening formed in one end surface 24a of the shield member 24) surrounded by each side of the U-shape. Is done. A slit 24c is formed in a surface corresponding to the U-shaped vertical bar (the other end surface 24b of the shield member 24), and the first FPC 22 is inserted into the slit 24c. The inserted first FPC 22 is sandwiched between the upper surface 24d of the shield member 24 and the lower surface located on the opposite side.

  The lower surface of the shield member 24 has a portion 24e that is bent at a substantially right angle in the middle thereof. This portion 24 e protects the second FPC 23 connected to the DC bias pin 12 a of the modulator 12. The bent portion 24e also has a shielding function against external noise. Further, after the installation of the power supply substrate 21 and the first FPC 22 to the shield member 24 is completed as described above, the hole portions 24f formed on both sides of the shield member 24, the hole portions 21f formed on both sides of the power supply substrate 21, and spacers A screw is inserted into the hole portion 25f formed on both sides of 25 and the hole portion 12f formed on one side surface 12b of the modulator 12, and the shield member 24 is fastened to the power supply substrate 21, the spacer 25, and the modulator 12 together. .

  Then, the four GPO cables 17 are connected to the connector portion 12 d provided on the side surface 12 c of the modulator 12. The GPO cable 17 provides a drive signal to the modulator 12. The GPO cable 17 is a so-called semi-rigid cable, has a predetermined characteristic impedance, and includes a central conductor, an insulator surrounding the central conductor, and a conductor coating (GND). The conductor coating is often formed of a metal sheath made of a flexible material.

  The GPO cable 17 can be easily bent and can maintain its bent shape. The GPO cable 17 is pre-formed into a shape as shown in FIG. 5 before being connected to the connector portion 12d of the modulator 12, and is connected to the connector portion 12d in this state. The first process of connecting the GPO cable 17 to the modulator 11 and assembling the modulator unit U1 including the power supply substrate 21 and the GPO cable 17 is completed.

  Next, the second process which is a process of mounting the light source unit U2 on the upper housing 2 will be described. As shown in FIG. 7, the light source unit U <b> 2 includes a tunable light source 13 and a control board (second board) 31 on which a control circuit that determines the wavelength of the tunable light source 13 is mounted. The light source unit U2 is normally fitted with a pigtail fiber state, that is, an internal fiber F1. A polarization maintaining connector P1 is attached to the end of the internal fiber F1 opposite to the side connected to the wavelength variable light source 13.

  The light source unit U2 is mounted and fixed at a predetermined location in the upper housing 2. Specifically, the light source unit U2 is mounted on the upper housing 2 with a part (front portion) of the light source unit U2 entering the spare space S1 provided inside the protruding portion 2a of the upper housing 2. This completes the second step of mounting the light source unit U2 on the upper housing.

  Next, the third step of mounting the previously assembled modulator unit U1 on the upper housing 2 will be described. As shown in FIG. 8, first, four GPO cables 17 are inserted into the four grooves 2b formed on the inner surface of the upper housing 2, and the connector 17a formed at the end of the GPO cable 17 is polarized. It is located above the connector P2. Behind the modulator 12, the internal fiber F4 drawn out from the modulator 12 is passed through a notch 2d formed in the rear wall 2c of the upper housing 2, and once pulled out behind the rear wall 2c. Then, the internal fiber F4 drawn out rearward of the rear wall 2c is dropped into an arc-shaped groove 2f formed in the protruding portion 2e of the upper housing 2. Further, the internal fiber F4 is passed through another notch 2g formed in the rear wall 2c.

  After the inner fiber F4 is routed by the protruding portion 2e of the upper housing 2 as described above, the cover 42 is covered with the groove 2f to protect the inner fiber F4. The cover 42 has three claw portions 42a, 42b, 42c arranged at both sides of the rear end portion and the center of the front end portion, and bent pieces 42d, 42e bent substantially vertically on both sides of the front end portion of the cover 42. And. The cover 42 is attached on the protruding portion 2e by engaging the claw portions 42a, 42b, and 42c with holes 2h, 2j, and 2k formed in the protruding portion 2e, respectively. Further, when the cover 42 is attached to the protruding portion 2e, the bent pieces 42d and 42e close the notches 2d and 2g.

  The internal fiber F4 is a polarization maintaining fiber from the modulator 12 toward the polarization maintaining coupler 14, and a polarization maintaining connector P2 is provided at the end of the internal fiber F4 opposite to the modulator 12. That is, the inner fiber F4 is drawn from the rear end of the modulator 12, and expands in a U-shape in the groove 2f provided outside the rear wall 2c. The internal fiber F4 that has passed through the notch 2g in the rear wall 2c and returned to the housing expands in front of the housing as it is, expands again in a U-shape in the spare space S1 at the front end of the housing, and moves backward. The polarization maintaining connector P2 provided at the rear end of the internal fiber F4 is connected to another polarization maintaining fiber F3 at a substantially central portion of the upper housing 2.

  On the other hand, the internal fiber F1 extending rearward from the light source unit U2 is also a polarization maintaining fiber toward the polarization maintaining coupler 14. The polarization maintaining connector P1 described above is connected to one end of the internal fiber F1. The internal fiber F <b> 1 is extended rearward from the light source unit U <b> 2, developed in a U shape without being pulled out of the housing at the rear portion of the housing 2, and travels forward along the modulator 12. After developing along the modulator 12, it is curved in a U shape in the spare space S1 and developed backward. A polarization maintaining connector P1 is connected to the rear end of the internal fiber F1. This polarization maintaining connector P1 is also connected to another polarization maintaining fiber F2 at a substantially central portion of the upper housing 2.

  The modulator unit U1 is fixed to the upper housing 2 by screwing the power supply board 21 into two screw holes on the inner surface of the upper housing 2. At this time, the housing of the modulator 12 is electrically insulated from the upper housing 2. This is because the housing of the modulator 12 is grounded to the signal GND while the signal GND is separated from the chassis GND. This improves the noise characteristics.

  As described above, since each GPO cable 17 is bent in a U shape, the driver 11 that is a drive IC of the modulator 12 can be efficiently arranged in the upper housing 2. In the present embodiment, a cable cover 44 (see FIG. 2) that closes the four grooves 2b in which the GPO cables 17 are accommodated is provided. The cable cover 44 is made of metal and exhibits a high heat dissipation effect for the driver 11 mounted on the cable cover 44. The third step of mounting the modulator unit on the housing is completed by closing the GPO cable 17 with the cable cover 44.

  Next, a fourth process for mounting the optical receiving unit U3 on one surface 7a of the main substrate 7 will be described. FIG. 9 is a perspective view showing one surface 7 a of the main substrate 7, and FIG. 10 is a perspective view showing the other surface 7 b of the main substrate 7. A signal processing IC (circuit) is mainly mounted on one surface 7 a of the main substrate 7. Specifically, the DSP 16 is disposed behind the planned mounting location of the optical receiving unit U 3, and the two drivers 11 are mounted behind the four GPPO connectors 45. The DSP 16 is an integrated circuit that generates heat of several tens of watts by itself.

  In the optical transceiver 1, a child board 8 that is separate from the main board 7 is mounted. A step-up DC / DC converter IC 46 is mounted on the sub board 8. Since the DC / DC converter IC 46 is equipped with a large-sized inductor, the overall height of the DC / DC converter IC 46 tends to increase. In the optical transceiver 1 of the present embodiment, the outer dimensions comply with the CFP standard, so that it is possible to ensure only a total height of just over 10 mm. In the main board 7, since components are mounted on both the one surface 7a and the other surface 7b, it is difficult to mount tall components on the one surface 7a or the other surface 7b.

  Considering the above points, in the optical transceiver 1 of this embodiment, the DC / DC converter IC 46 is mounted on the sub board 8 and the horizontal position of the sub board 8 is set lower than the main board 7. By mounting components on the sub-board 8 lower than the horizontal position of the main board 7 in this way, tall components can be mounted in a limited space in the optical transceiver 1. The child board 8 is fixed to the main board 7 with conductive pins, and is electrically connected to the main board 7 by the FPC 48. Since components mounted on the sub board 8 need to process a large current, both boards are fixed by pins for flowing a large current supplied from the main board 7.

  A wiring pattern is not formed on the back surface 8 a of the sub board 8. The back surface 8a of the sub board 8 can be brought into direct contact with the sealing member 3a (see FIG. 16) of the lower housing 3. Further, by bringing the back surface 8a of the daughter board 8 into contact with the sealing member 3a, the heat radiation effect of the DC / DC converter IC 46 and the like mounted on the front surface is enhanced. Furthermore, the sealing member 3a is formed thin and secures a mounting margin for tall components (detailed later).

  Next, a method for mounting the optical receiving unit U3 including the ICR 15 will be described. FIG. 11 is an exploded perspective view showing the optical receiving unit U3 and the main board 7. As shown in FIG. As shown in FIG. 11, the optical receiving unit U3 includes an ICR 15, a holder 51 that holds the ICR 15, two DC signal FPCs 52 and 53, and an RF signal FPC 54.

  The ICR 15 has a rectangular shape, and a pin row 15b for DC signals is arranged on the side wall 15a. The wall on the rear side (DSP 16 side) of the ICR 15 is provided with a pin row (not shown) for RF signals. The ICR 15 is mounted on one surface 7 a of the main substrate 7 via the holder 51. The holder 51 holds the ICR 15 on one surface 7a.

  FIG. 12 is a diagram showing a positional relationship between the ICR 15, the holder 51, and the DC signal FPCs 52 and 53. As shown in FIG. As shown in FIGS. 11 and 12, the two FPCs 52 and 53 connected to the pin row 15b of the ICR 15 pass through the gap S2 between the holder 51 and the main substrate 7 and are electrode pads 7c on the main substrate 7. , 7d.

  The FPC 52 is connected to the center side (right side in FIG. 12) of the optical transceiver 1, extends downward from the pin row 15 b, is bent at a substantially right angle along the holder 51, and the FPC 52 is connected to the holder 51 and the main board 7. After the gap S <b> 2 is passed between the end portions of the transceiver 1 and then expanded upward, it is further folded outward in a U shape. Thereafter, the gap S <b> 2 is developed again and then connected to the electrode pad 7 c on the main substrate 7. The electrode pad 7 c is provided immediately below the holder 51 and on the center side of the optical transceiver 1.

  The other FPC 53 is soldered to a pin row 15 b located on the transceiver end side of the ICR 15. The FPC 53 expands upward from the pin row 15b, is folded back in a U shape so as to surround the previous FPC 52 folded back in a U shape, and is expanded downward, and then at an angle of approximately 90 ° toward the gap S2. It is bent and connected to the electrode pad 7 d on the main substrate 7. In the gap S2, the FPC 52 is located above the FPC 53, and the electrode pad 7d corresponding to the FPC 53 is directly below the holder 51 and is closer to the end of the optical transceiver 1 than the electrode pad 7c corresponding to the FPC 52 ( Provided on the left side). The curvature of the portion of the FPC 52 that is folded back into the U shape is smaller than the curvature of the portion of the FPC 53 that is folded back into the U shape.

  As described above, since the electrode pads 7c and 7d on the main substrate 7 are located immediately below the holder 51, after the holder 51 is installed on the main substrate 7, the electrode pads 7c and 7d can be visually recognized or the electrode pads 7c can be visually recognized. , 7d cannot be soldered. Therefore, the assembly is performed in the order of soldering the FPCs 52 and 53 to the electrode pads 7 c and 7 d and then mounting the ICR 15 on the holder 51.

  Specifically, first, an intermediate assembly in which the FPCs 52 and 53 are connected to the respective pin rows 15b of the ICR 15 is manufactured, then the FPC 52 is connected to the electrode pad 7c, and the other FPC 53 is connected to the electrode pad 7d. Thereafter, the holder 51 is installed on the main board 7 and the ICR 15 is mounted on the main board 7 so that the ICR 15 is wound by the two FPCs 52 and 53. Finally, the fourth step is completed by soldering the RF signal FPC 54 to the RF signal pin array of the ICR 15 and soldering the other end of the FPC 54 to a predetermined electrode pad of the main board 7.

  Here, the holder 51 is provided with a plurality of bent portions 51a bent in a U shape in order to secure the gap S2 below the ICR 15. In addition, the extension 51c bent upward from the main surface 51b of the holder 51 is formed with a hook bent toward the center side of the holder 51 at the upper end, and the hook is surrounded by the part 51c. The ICR 15 mounted in the area is suppressed. The four extending portions 51c are provided on the front, rear, left, and right sides of the ICR 15. The holder 51 is provided with a leg portion 51d whose tip is bent below the main surface 51b and outside the holder 51. The leg portion 51d presses the polarization maintaining coupler 14 against the main substrate 7. (It will be described in detail later).

  Since the signals transmitted by the two FPCs 52 and 53 are a DC signal and a GND, even if the total length is increased, the influence on the signal quality is small. Therefore, this embodiment can adopt the housing structure for the signal FPCs 52 and 53 as described above. Such a housing structure for the FPCs 52 and 53 enables the optical receiving unit U3 to be mounted on the main board 7 in a compact manner.

  At this stage, the internal fiber F5 may be connected to the polarization maintaining connector P3 of the ICR15. That is, the ICR 15 and the polarization maintaining coupler 14 can be connected by engaging the internal fiber F5 pigtailed to the polarization maintaining coupler 14 with the polarization maintaining connector P3. In addition to the internal fiber F5, the polarization maintaining coupler 14 is pigtail-connected to an internal fiber F2 toward the wavelength tunable light source 13 and an internal fiber F3 toward the modulator 12.

  Further, various ICs are mounted on the main board 7, and the ICs mounted on the main board 7 operate with considerable heat generation. In particular, when the operation speed exceeds 10 Gbps, the heat generation amount reaches several tens of watts. Therefore, in order to promote the heat radiation from each IC, a heat radiation gel is applied in advance to the IC mounting position on the inner surface of the upper housing 2 and the mounting positions of each IC on the main substrate 7.

  Specifically, for example, 4 on the cable cover 44; a location facing the mounting location of the DSP 16; an inner surface facing the mounting location of the DC / DC converter IC 46 on the sub board 8; a location contacting the top surface of the ICR 15; Apply heat-dissipating gel to the place. On the other hand, on the main substrate 7, a heat dissipating gel is applied to the top surface 4 of each of the driver 11, DSP 16, DC / DC converter IC 46, and ICR 15.

  Next, the fifth step of mounting the main board 7 on the upper housing 2 will be described. In the fifth step, as shown in FIG. 13, the other surface 7 b of the main substrate 7 is exposed and the main substrate 7 is accommodated in the upper housing 2. Then, the sub board 8 covers the modulator 12 mounted on the upper housing 2. At this time, the DC / DC converter IC 46 on the sub board 8 is in thermal contact with the housing of the modulator 12. The sub board 8 does not interfere with the shield member 24 of the modulator unit U1, and is arranged behind the shield member 24 and separated from the shield member 24. Thus, the fifth step is completed by arranging the components.

  Next, a sixth step of mounting the polarization maintaining coupler 14 on the other surface 7b of the main substrate 7 is performed. As shown in FIG. 14, in the sixth step, the polarization maintaining coupler 14 is attached to the side portion of the main substrate 7. The main substrate 7 is provided with a notch 7f, and the leg 51d of the holder 51 is exposed from the notch 7f. Both ends of the polarization maintaining coupler 14 are placed on the other surface 7b, the central portion of the polarization maintaining coupler 14 is positioned above the notch 7f, and the polarization maintaining coupler 14 is inserted inside the leg 51d. Thus, by passing the polarization maintaining coupler 14 inside the leg 51 d, the leg 51 d presses the polarization maintaining coupler 14 against the main substrate 7. Accordingly, mechanical holding of the polarization maintaining coupler 14 with respect to the main board 7 is realized, and the sixth step is completed.

  Next, each of the internal fibers F1 to F7 is engaged with the polarization maintaining connectors P1 and P2 located at the approximate center of the upper housing 2. FIG. 15 is a diagram schematically showing the arrangement of the internal fibers F1 to F7. With reference to FIG. 15, the seventh step of connecting the light source unit U2 and the polarization maintaining coupler 14 by the polarization maintaining connector P1 and the internal fibers F1, F2 will be described.

  As shown in FIG. 15, the internal fiber F <b> 1 drawn from the wavelength tunable light source 13 extends to the rear portion of the upper housing 2 and is folded back at the rear portion of the upper housing 2. The folded inner fiber F1 is unfolded forward on the side of the modulator 12, and is folded back again in the spare space S1 of the upper housing 2. Thereafter, it is connected to the polarization maintaining connector P <b> 1 near the center of the upper housing 2.

  The internal fiber F2 drawn out from the polarization maintaining connector P1 extends to the rear part of the upper housing 2 and is folded back so as to go around the modulator 12 at the rear part of the upper housing 2. The folded inner fiber F2 is folded back toward the rear in the spare space S1 through the outside of the modulator 12, and is connected to the polarization maintaining coupler 14 through the side of the wavelength variable light source 13 and the rear of the receptacle 18. . In this way, the seventh step is completed by connecting the tunable light source 13 and the polarization maintaining coupler 14 to each other by the internal fibers F1 and F2 and the polarization maintaining connector P1.

  Next, an eighth step of connecting the polarization maintaining coupler 14 and the modulator 12 by the polarization maintaining connector P2 and the internal fibers F3 and F4 will be described. The internal fiber F3 extending from the polarization maintaining coupler 14 extends rearward, is folded back toward the front at the rear portion of the upper housing 2, and is then connected to the polarization maintaining connector P2.

  The internal fiber F4 drawn from the polarization maintaining connector P2 is unfolded forward by the side of the wavelength tunable light source 13, folded back toward the rear in the spare space S1, and unfolded rearward by passing by the side of the modulator 12. Once it passes through the rear wall 2c of the upper housing 2 and is pulled out to the outside, it is folded back outside the housing. Thereafter, it passes through the rear wall 2c and is drawn into the housing again, and is connected to the modulator 12 in the immediate vicinity of the rear wall 2c. By connecting the polarization maintaining coupler 14 and the modulator 12 in this way, the eighth step is completed.

  Next, the ninth step of connecting the polarization maintaining coupler 14 and the optical receiving unit U3 (ICR15) with the polarization maintaining connector P3 and the internal fiber F5 will be described. The inner fiber F5 extending rearward from the polarization maintaining coupler 14 is folded toward the modulator 12 at the rear portion of the upper housing 2, passes through the outside of the modulator 12, expands to the front of the housing, and reaches the receptacle in front of the spare space. Is bent toward the side and passes through the back of the receptacle 18 to connect to the polarization maintaining connector P3 of the ICR15.

  Most of the internal fiber F5 is exposed on the main substrate 7 (see FIG. 14), and is hooked and held by a claw 24g formed outside the shield member 24 of the modulator unit U1. As described above, the ninth step is completed by connecting the polarization maintaining coupler 14 and the ICR 15 by the internal fiber F5 and the polarization maintaining connector P3.

  As mentioned above, about the 7th-9th process which wires internal fiber F1-F5, it is possible to perform these processes in random order. For example, the ninth step may be performed before the fifth step of mounting the main board 7 on the upper housing 2.

  Next, the tenth step of connecting the modulator 12 and the receptacle 18 with the internal fiber F6 and connecting the receptacle 18 and the optical receiving unit U3 with the internal fiber F7 will be described. In the tenth step, the internal fiber F6 and one terminal 18a of the receptacle 18 are assembled, and the internal fiber F7 and the other terminal 18b of the receptacle 18 are assembled.

  The internal fiber F6 is drawn forward from the modulator 12, expanded to the spare space S1, and then folded back so as to surround the light source unit U2 in the spare space S1. Thereafter, the light passes through the rear of the wavelength tunable light source 13 and the side of the center of the transceiver of the modulator 12 and expands to the rear of the upper housing 2 and is folded back toward the position corresponding to the terminal 18a at the rear of the upper housing 2. This is connected to the terminal 18a of the receptacle 18 as it is.

  On the other hand, the internal fiber F7 for propagating the input signal light from the receptacle 18 extends rearward through the side of the center of the optical transceiver of the ICR 15 after being drawn out from the terminal 18b, and the modulator at the rear of the upper housing 2 12 Folded toward that side. Thereafter, the outside of the modulator 12 is expanded forward, bent toward the receptacle in front of the modulator 12, and connected to the ICR 15 through the rear of the receptacle 18. As described above, the tenth process is completed by connecting the modulator 12 and the receptacle 18 and connecting the receptacle 18 and the ICR 15. As shown in FIG. 3, when the tenth step is completed, the inner fibers F1 and F4 are hidden by the main substrate 7, and a part of the inner fibers F2, F3, F5 to F7 are exposed on the main substrate 7. doing.

  As described above, in the method for manufacturing the optical transceiver 1 according to the present embodiment, a large number of components can be arranged with high accuracy through the first to tenth steps described above. Further, after the tenth step, a step of electrically connecting the main substrate 7 and the light source unit U2 and a step of electrically connecting the main substrate 7 and the modulator unit U1 are performed.

  Specifically, a connector provided with an FPC 7e extending from the main board 7 toward the light source unit U2 is engaged with the connector of the light source unit U2. Next, the first FPC 22 that connects the modulator unit U <b> 1 and the main board 7 is soldered to the electrode of the main board 7.

  Then, a process of assembling the lower housing 3 to the upper housing 2 is executed. In this step, after the engagement screws are installed on both sides of the upper housing 2, the lower housing 3 is aligned with the upper housing 2. Here, as shown in FIG. 16, an opening 3b penetrating the lower housing 3 is formed at a location facing the child substrate 8 of the lower housing 3, and the sealing member 3a described above is formed in the opening 3b. It has entered.

  The sealing member 3a and the opening 3b have a rectangular shape, and the sealing member 3a is made of SUS. The sealing member 3a has a plate shape that covers the opening 3b, and is fitted into the opening 3b from the inside. In the lower housing 3, the height of the location where the sealing member 3a is provided is lower than the height of the location where the sealing member 3a is not provided. That is, the thickness of the sealing member 3a is thinner than the thickness of the lower housing 3 main body.

  Here, when both the upper housing 2 and the lower housing 3 are manufactured by aluminum die casting, the thickness of the upper housing 2 and the lower housing 3 is required to be at least about 0.5 mm. Further, as described above, the DC / DC converter IC 46 mounted on the child board 8 tends to be a tall component. If the sub board 8 and the DC / DC converter IC 46 are simply stacked on the main body of the lower housing 3, the height of the external dimensions defined by the standard may be exceeded if component tolerances, manufacturing variations, and the like are taken into account. .

  In order to avoid the above problems, the lower housing 3 of the present embodiment is provided with a sealing member 3a and an opening 3b. That is, the height of the optical transceiver 1 is suppressed by pulling out the portion of the lower housing 3 facing the sub board 8 to form the opening 3b and fitting the thinner sealing member 3a into the opening 3b. When a SUS plate having a thickness of about 0.2 mm is used as the sealing member 3a, the same strength as that of die-cast aluminum can be secured, so that no problem arises from the viewpoint of mechanical strength. Further, the thermal conductivity of SUS and the thermal conductivity of aluminum are approximately the same.

  As mentioned above, although preferred embodiment which concerns on this invention has been described, this invention is not limited to embodiment mentioned above. That is, it is easily recognized by those skilled in the art that various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

DESCRIPTION OF SYMBOLS 1 ... Optical transceiver, 2 ... Upper housing (housing), 2a ... Projection part, 2b ... Groove, 2c ... Rear wall, 2d, 2g ... Notch, 2e ... Projection part, 2f ... Groove, 2h, 2j, 2k ... Hole DESCRIPTION OF SYMBOLS 3 ... Lower housing (housing), 3a ... Sealing member, 3b ... Opening, 4 ... Screw, 4a ... Rear end part, 5 ... Front panel, 6 ... Electric plug, 7 ... Main board (3rd board), 7a ... One surface, 7b ... The other surface, 7c, 7d ... Electrode pad, 7e ... FPC, 7f ... Notch, 7g ... Connector, 8 ... Sub-board, 8a ... Back surface, 11 ... Driver, 12 ... Modulator, 12a ... DC bias pin, 12b ... one side, 12c ... side, 12d ... connector, 12f ... hole, 13 ... tunable wavelength light source, 13a ... connector, 14 ... polarization maintaining coupler, 15 ... ICR, 15a ... side, 15b ... Pin row, 16 ... DSP, 7 ... GPO cable, 17a ... connector, 18 ... receptacle, 18a ... terminal (one terminal), 18b ... terminal (other terminal), 21 ... power supply board (first board), 21a ... back surface, 21b ... pad, 21f ... hole part, 22 ... first FPC, 23 ... second FPC, 24 ... shield member, 24c ... slit, 24d ... upper surface, 24e ... bent part, 24f ... hole part, 24g ... claw, 25 ... spacer, 25a ... central part, 31 ... Control board (second board), 42 ... Cover, 42a, 42b, 42c ... Claw part, 42d, 42e ... Bent piece, 44 ... Cable cover, 45 ... GPPO connector, 47 ... Screw, 51 ... Holder, 51a ... Bending part, 51b ... main surface, 51c ... extension part, 51d ... leg part, 52, 53 ... DC signal FPC, 54 ... RF signal FPC, C1, C2, C3 ... light Nector, F1, F2 ... Internal fiber (first polarization maintaining fiber), F3, F4 ... Internal fiber (second polarization maintaining fiber), F5 ... Internal fiber (third polarization maintaining fiber), F6 ... Internal fiber ( First single mode fiber), F7... Internal fiber (second single mode fiber), P1... Polarization maintaining connector (first polarization maintaining connector), P2... Polarization maintaining connector (second polarization maintaining connector) , P3: Polarization maintaining connector (third polarization maintaining connector), S1: Preliminary space, S2: Clearance, U1: Modulator unit, U2: Light source unit, U3: Optical receiving unit.

Claims (6)

A method of manufacturing a coherent optical transceiver in which a modulator, a wavelength tunable light source, an optical receiving unit, and a polarization maintaining coupler are mounted in a housing,
A first step of assembling a modulator unit including the modulator, a first substrate on which a circuit for applying a bias to the modulator, and a cable for outputting a drive signal to the modulator, outside the housing;
A second step of mounting a light source unit including the wavelength tunable light source and a second substrate on which a circuit for determining a wavelength of the wavelength tunable light source is mounted on the housing;
A third step of mounting the modulator unit on the housing;
A fourth step of mounting the optical receiving unit on one surface of a third substrate;
A fifth step of mounting the third substrate on which the optical receiving unit is mounted on the housing with the other surface of the third substrate exposed;
A sixth step of mounting the polarization maintaining coupler on the other surface of the third substrate;
A seventh step of connecting the light source unit and the polarization maintaining coupler by a first polarization maintaining connector and a first polarization maintaining fiber;
An eighth step of connecting the polarization maintaining coupler and the modulator by a second polarization maintaining connector and a second polarization maintaining fiber;
A ninth step of connecting the polarization maintaining coupler and the optical receiving unit by a third polarization maintaining connector and a third polarization maintaining fiber;
A tenth step of connecting the modulator and a receptacle mounted on the housing by a first single mode fiber, and connecting the receptacle and the optical receiving unit by a second single mode fiber;
The seventh step, the eighth step and the ninth step are executed in any order.
Manufacturing method of optical transceiver. In the ninth step, the third polarization maintaining fiber is engaged with the third polarization maintaining connector connected to the optical receiving unit.
The method of manufacturing an optical transceiver according to claim 1. The receptacle comprises at least two terminals;
In the tenth step, one terminal of the receptacle is assembled to the first single mode fiber.
A method for manufacturing the optical transceiver according to claim 1. In the tenth step, the other terminal of the receptacle is assembled to the second single mode fiber.
The method for manufacturing an optical transceiver according to claim 3. In each of the seventh step and the eighth step, the first polarization maintaining connector and the second polarization maintaining connector are engaged with the other surface of the third substrate.
The manufacturing method of the optical transceiver as described in any one of Claims 1-4. After the tenth step, the method includes a step of electrically connecting the third substrate and the light source unit, and a step of electrically connecting the third substrate and the modulator unit.
The manufacturing method of the optical transceiver as described in any one of Claims 1-5.

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