JP4699155B2 - Optical module - Google Patents

Description

  The present invention relates to an optical module, and more particularly to an optical module that is mounted on a mounting board together with a PLC on which a functional element is formed, and constitutes an optical transceiver.

  In recent years, with the spread of optical fiber transmission, a technique for integrating a large number of optical elements with high density has been demanded. As one of them, a planar lightwave circuit (hereinafter referred to as “PLC: Planar Lightwave Circuit”) is known. . The PLC is an optical circuit in which an optical device composed of an optical waveguide and an optical waveguide is integrated on a silicon substrate or a quartz substrate, has high productivity and reliability, and is excellent in terms of integration and high functionality. The optical transceiver at the transmission terminal station is mounted with a light emitting element such as an LD, a light receiving element such as a PD, and a PLC on which functional elements such as a multiplexer / demultiplexer, a branch / coupler, and an optical modulator are formed. Yes.

  In the optical transceiver, the light emitting / receiving element and the PLC are connected by optically coupling or directly joining the light emitting element module and / or the light receiving element module (hereinafter referred to as an optical module) and the PLC with an optical disc component. Things have been done. FIG. 1 shows a method of directly joining a conventional optical module and a PLC.

  FIG. 2 shows the configuration of a conventional optical module. As an example, the optical module 11 includes four light emitting elements or light receiving elements (hereinafter referred to as optical elements) 15 having a light emitting surface or a light receiving surface (hereinafter referred to as light receiving / emitting surface) 14. The optical element 15 is sealed by a box-shaped housing 12 and a lid 13 made of sapphire glass that enables input and output of optical signals to and from the light receiving and emitting surface 14 (see, for example, Non-Patent Document 1). . Since the casing 12 and the lid 13 are joined by metal solder and have high airtightness, the casing 12 and the lid 13 are protected from the external environment and ensure the reliability of the optical element 15. The optical element 15 is fixed to the housing 12 with metal solder or the like with the light emitting / receiving surface 14 facing the lid 13, and connected to the metal wiring 17 of the housing 12 by bonding wires 16. The metal wiring 17 extends through the housing 12 to the back surface and side surface of the housing 12.

  On the other hand, the PLC 21 has an optical waveguide 24 formed on the silicon substrate 22. The optical waveguide 24 formed in the PLC 21 and the light emitting / receiving surface 14 of the optical element 15 are disposed so as to be optically coupled. A short plate 23 as a reinforcing plate is bonded onto the PLC 21, and is bonded to the lid 13 of the optical module 11 on the surface including the end surface of the optical waveguide 24 of the PLC 21. A UV curable adhesive or the like is used for joining the optical module 11 and the PLC 21. The optical module 11 and the PLC 21 are fixed on the mounting board 31, and the metal wiring 17 of the optical module 11 and the electrode 32 connected to the metal wiring 34 formed on the mounting board 31 are connected by the bonding wire 33. .

A. Kaneko, et al, “Ultra small and low power consumption 8ch variable optical attenuator multiplexer (V-AWG) using multi-chip PLC integration technology”, Proc. OFC’2005, OTuD3

  In the optical transceiver, when the optical module and the PLC are connected by the optical disc component, the mounting space is increased. Therefore, as described above, the optical module and the PLC are directly joined. However, in the conventional method described above, when a functional element such as an optical switch that also uses the thermo-optic effect is mounted on the PLC 21, a large amount of heat is generated. In particular, since the silicon substrate 22 of the PLC 21 has a high thermal conductivity, the optical module 11 bonded to the PLC 21 is easily affected by the heat of the PLC 21. Accordingly, there is a problem that the characteristics of the optical element 15 mounted on the optical module 11 are deteriorated.

  In addition, since the metal wiring 17 of the optical module 11 and the electrode 32 formed on the mounting board 31 are connected by the bonding wire 33, there is a problem that it is difficult to ensure the mechanical strength and is easily disconnected. It was. In particular, there is a problem that the reliability with respect to vibration is inferior.

  Furthermore, in the optical transceiver assembly process, in order to optically couple the light receiving / emitting surface 14 of the optical element 15 and the optical waveguide 24 of the PLC 21, the process of fixing the optical element 15 to the housing 12; In the process of joining the optical module 11 and the PLC 21, there is also a problem that it is difficult to ensure the mounting position accuracy.

  The present invention has been made in view of such a problem, and an object of the present invention is to be able to connect without being affected by heat from the PLC while ensuring electrical connection with the mounting board. An object of the present invention is to provide an optical module that can ensure mechanical strength.

In order to achieve such an object, the present invention is characterized in that the invention according to claim 1 includes a housing that is open only on one side, a lid that transmits light and closes and seals the opening of the housing. In an optical module including an optical element fixed with the light emitting / receiving surface facing the lid, one end surface is optically coupled to a plurality of optical waveguides of a planar optical waveguide circuit, and the other end surface is arrayed a glass block which holds the arrayed fiber optic so that each optically coupled through said lid and a plurality of light emitting and receiving surface of the optical element, the other end face and the same flat surface of the optical fiber A metal block electrically connected to the optical element and penetrating from the inside of the housing to the outside of the housing, and the metal wiring outside the housing And lead pins bonded to the mounting board. So mounting surface and the optical axis of the optical element is parallel, characterized in that fixed to the mounting board.

  As described above, according to the present invention, the optical fiber optically coupled to the light receiving / emitting surface of the optical element is held, and the optical fiber connecting means joined to the lid is provided on the surface including the end face of the optical fiber. Therefore, the optical module is not affected by heat from the PLC by being connected to the PLC via the optical fiber.

  Further, according to the present invention, since the metal wiring formed so as to penetrate outside the housing and the lead pin joined to the metal wiring are provided, the mechanical strength is ensured while ensuring the electrical connection. It becomes possible to do.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(Method for joining optical module and PLC-1)
FIG. 3 shows a method of joining the optical module and the PLC according to the first embodiment of the present invention. The optical module 51 has the same structure as the optical module 11 shown in FIG. 1 and includes an optical element 55 sealed with a box-shaped casing 52 and a lid 53 made of sapphire glass. In the case where a PLC that does not have a functional element that generates heat is bonded to an optical module, the PLC can be directly bonded as shown in FIG. However, when the PLC mounting the functional element that generates heat and the optical module are joined, the method described below is used.

  The optical module 51 is fixed so that the mounting surface of the mounting board 81 and the optical axis of the optical element 55 of the optical module 51 are parallel to each other. Since the metal wiring 57 of the optical module 51 and the electrode 82 formed on the mounting board 81 are fixed by metal solder or the like, the optical module 51 can be firmly fixed on the mounting board 81.

  The light receiving / emitting surface 54 of the optical element 55 of the optical module 51 is optically coupled to the optical fiber 92 fixed to the glass block 91. The glass block 91 as the optical fiber connecting means is bonded to the lid 53 of the optical module 51 using an adhesive or the like on the surface including the end surface of the optical fiber 92.

  On the other hand, the PLC 21 is bonded to the substrate 22, and the optical waveguide formed on the PLC 21 is optically coupled to the optical fiber 92 fixed to the glass block 93. The optical fiber 92 is bonded to the glass block 93 on the surface including the end face of the optical waveguide of the PLC 21 with the sheath 23 on the PLC 21 as a reinforcing plate. In this way, since the optical module 51 and the PLC 21 are connected via the optical fiber 92, the optical module 51 is not affected by the heat of the PLC 21.

  Further, since the mounting surface of the mounting board 81 and the optical axis of the optical element 55 of the optical module 51 are fixed in parallel, it is possible to suppress the component height on the mounting board 81. The optical transceiver can be configured.

(Optical module)
FIG. 4 shows a configuration of an optical module according to an embodiment of the present invention. The optical module 51 includes an optical element 55 sealed with a box-shaped casing 52 and a lid 53 made of sapphire glass that transmits light. For example, alumina ceramics is used as the material of the casing 52. A metal for bonding is formed on the outside of the peripheral edges of the casing 52 and the lid 53 by metal vapor deposition. Metal solder is used as a bonding agent for bonding the casing 52 and the lid 53. Since the casing 52 and the lid 53 have high airtightness, they are protected from the external environment and the reliability of the optical element 55 can be ensured.

  The optical element 55 is a light emitting element such as an LD or a light receiving element such as a PD. The optical element 55 is fixed to the casing 52 with metal solder or the like with the light emitting / receiving surface 54 facing the lid 53, and connected to the metal wiring 57 of the casing 52 by a bonding wire 56. The metal wiring 57 extends through the housing 52 to the back and side surfaces of the housing 52. Lead pins 58 are fixed to the metal wiring 57 on the back surface of the casing 52 by welding (brazing or the like).

  FIG. 5 shows an example of an optical module mounting method. An electrical connector to be fitted to the lead pin 58 is prepared in advance. The electrical connector may be the connector 60 fixed to the mounting board, or the connector 61 connected to the flexible cable 62 or the like. For example, if a measuring instrument or the like is connected to one of the flexible cables 62 using the connector 61, the characteristic evaluation or the operation test of the optical module 51 can be easily performed. According to this method, the inspection process before shipment of the optical module 51 can be easily performed, leading to cost reduction.

  FIG. 6 shows another application example of the configuration of the optical module. The optical module 71 includes a box-shaped casing 72 that is open in two directions, and lids 73a and 73b made of sapphire glass that seal the openings in the two directions. The optical element 75 has light receiving and emitting surfaces 74a and 74b in two directions, is opposed to the lids 73a and 73b, and is fixed to the casing 72 with metal solder or the like, and is bonded to the casing 72 by bonding wires 76a and 76b. It is connected to the metal wiring 77a, 77b. The metal wirings 77 a and 77 b extend through the housing 72 to the side surface of the housing 72. Lead pins 78a and 78b are fixed to the metal wirings 77a and 77b on the side surface of the housing 72 by welding (such as brazing).

(Method of joining optical module and PLC-2)
FIG. 7 shows a method for joining an optical module and a PLC according to the second embodiment of the present invention. The optical module 51 has the same structure as the optical module 51 shown in FIG. 4, and includes an optical element 55 sealed by a box-shaped casing 52 and a lid 53 made of sapphire glass. In the case where a PLC that does not have a functional element that generates heat is bonded to an optical module, the PLC can be directly bonded as shown in FIG. However, when the PLC mounting the functional element that generates heat and the optical module are joined, the method described below is used.

  The optical module 51 is fixed so that the mounting surface of the mounting board 81 and the optical axis of the optical element 55 of the optical module 51 are parallel to each other. Since the metal wiring 57 of the optical module 51 and the electrode 82 formed on the mounting board 81 are fixed by metal solder or the like via the lead pins 58, the optical module 51 can be firmly fixed on the mounting board 81. . The fixing agent for fixing the lead pin 58 to the mounting board 81 is not limited to metal solder but may be a conductive adhesive. It is preferable to use a solder that has a sufficient mechanical strength and can be repaired.

  The light receiving / emitting surface 54 of the optical element 55 of the optical module 51 is optically coupled to the optical fiber 92 fixed to the glass block 91. The glass block 91 as the optical fiber connecting means is bonded to the lid 53 of the optical module 51 using an adhesive or the like on the surface including the end surface of the optical fiber 92.

  On the other hand, the PLC 21 is bonded to the substrate 22, and the optical waveguide formed on the PLC 21 is optically coupled to the optical fiber 92 fixed to the glass block 93. A sheath 23 as a reinforcing plate is joined on the PLC 21 and joined to the glass block 93 on the surface including the end face of the optical waveguide of the PLC 21. In this way, since the optical module 51 and the PLC 21 are connected via the optical fiber 92, the optical module 51 is not affected by the heat of the PLC 21.

  Further, since the mounting surface of the mounting board 81 and the optical axis of the optical element 55 of the optical module 51 are fixed in parallel, it is possible to suppress the component height on the mounting board 81. The optical transceiver can be configured.

  FIG. 8 shows a method for joining the optical module and the glass block. The optical module 51 integrates four optical elements 55, and the optical fiber 92 that optically couples is a four-core tape type optical fiber array. The arrangement pitch of the cores of the optical fiber 92 and the arrangement pitch of the light receiving and emitting surfaces 54 of the optical element 55 coincide with each other. The connection between the metal wiring 57 of the optical module 51 and the electrode 82 formed on the mounting board 81 is fixed by metal solder or the like via the lead pin 58.

  Here, not only the electrodes 82a to 82d for driving the optical element 55 but also the ground pins 82e and 82f, for example, can be used to fix the lead pins 58a to 58f more firmly. If more strength is required, the number of lead pins may be increased. Further, the lead pins are arranged in only three directions in FIG. 8, but they may be arranged in four directions.

(Optical transceiver)
FIG. 9 shows a configuration of an optical transceiver according to an embodiment of the present invention. The optical transceiver 100 includes a mounting board 111 on which an optical module 112 incorporating a plurality of light emitting elements and an optical module 113 incorporating a plurality of light receiving elements are fixed, and an AWG type optical multiplexer / demultiplexer 131. . The optical module 112 and the optical module 113 are optically coupled to the tape-type optical fibers 121 and 122 by glass blocks 114 a and 114 b and connected to the AWG type optical multiplexer / demultiplexer 131. The AWG type optical multiplexer / demultiplexer 131 is temperature-controlled by the Peltier element 132, but is connected to the optical modules 112 and 113 via the optical fibers 121 and 122. There is no impact.

  The optical modules 112 and 113 are fixed so that the mounting surface of the mounting board 111 and the optical axes of the light emitting elements and the light receiving elements of the optical modules 112 and 113 are parallel to each other. This can be suppressed. Further, since the connection between the optical modules 112 and 113 and the AWG type optical multiplexer / demultiplexer 131 is performed through the fiber extra length processing unit 141 provided in advance in the optical transceiver 100, the mounting space is efficiently used. be able to.

Hereinafter, a method for joining the optical module and the glass block will be described with specific examples.
Example 1
FIG. 10 shows a method for joining the optical module and the glass block according to the first embodiment. The optical module 51 has the same structure as the optical module 51 shown in FIG. 4, and includes an optical element 55 sealed by a box-shaped casing 52 and a lid 53 made of sapphire glass. A difference from the joining method shown in FIG. 7 is that the optical module 51 is mounted and fixed to the mounting board 81 by fitting the connector 60 fixed to the mounting surface of the mounting board 81 and the lead pin 58.

  According to this method, the optical module 51 can be easily mounted in the assembly process of the optical transceiver. In the joining method shown in FIG. 7, after aligning with the electrode on a mounting board, the process of reflowing solder and fixing an optical module is required. In the solder reflow process, since the optical module directly receives heat during reflow, the characteristics of the optical element may be deteriorated. Therefore, by attaching to the connector 60 arranged on the mounting board 81, it is possible to avoid the problem of heat during solder reflow.

  Furthermore, even after the assembly of the optical transceiver, even if the optical module 51 breaks down, the replacement of the optical module 51 can be easily performed. In the first embodiment, an example in which the optical fiber 92 is attached to the optical module 51 is shown, but it goes without saying that the present invention can be applied even when a PLC is directly attached to the optical module 51.

(Example 2)
In FIG. 11, the joining method of the optical module concerning Example 2 and a glass block is shown. In Example 2, a ferrule or an optical connector is used instead of the glass block. Since the optical module 51 is provided with the lead pins 58, the fixing to the mounting board is strengthened, so that the optical module 51 has a mechanical strength that can withstand repeated insertion and removal of the ferrule or the optical connector. Therefore, when fixing the optical module to the mounting board, it becomes possible to attach optical cords such as optical fibers that have been complicated to handle in a later process, greatly reducing the man-hours in the assembly process of the optical transceiver. Thus, the manufacturing cost can be reduced.

In FIG. 11A, the MT ferrule 302 is used to optically couple the optical element of the optical module 51 and the optical fiber. A connector 301 having connection pins 311a and 311b is joined to the optical module 51. Connecting pins 311a, 311b are connected pinholes 321a of the MT ferrule 302, connected to fitting engagement with 321b, crimped by a metal of the leaf spring 303.

FIG. 11B optically couples the optical element of the optical module 51 and the optical fiber using an optical connector 304 such as an MPO connector or an MPX connector. A connector 305 having connection pins 351a and 351b is joined to the optical module 51. Connecting pins 351a, 351b are connected pinhole 341a of the optical connector 304, connected to fitting engagement with 341b.

  The number of optical fiber core wires of the ferrule or optical connector is the same as the number of optical elements built in the optical module, and the number of core wires is not limited. Further, when attachment / detachment with a ferrule or an optical connector is not necessary, the ferrule end face may be directly joined to the lid of the optical module using an adhesive.

(Example 3)
FIG. 12 shows a method for joining an optical module and a glass block according to Example 3. The optical element 155 of the optical module 151 is optically coupled to the optical fiber 162 fixed to the glass block 161. The glass block 161 is bonded to the lid 153 of the optical module 151 on the surface including the end surface of the optical fiber 162.

A convex portion 163 is provided on the end surface of the glass block 161, and a concave portion 155 is provided on the lid 153. The convex portion 163 and the concave portion 155 are fitted so that the light emitting / receiving surface 154 of the optical element 155 and the core of the optical fiber 162 are optically coupled. In this way, alignment between the optical element 155 and the optical fiber 162 can be facilitated. Of course, a concave portion may be provided on the end surface of the glass block 161 and a convex portion may be provided on the end surface of the lid 153.

  In the case where the optical module and the PLC are directly connected, if a convex portion (or a concave portion) is formed on the end surface of the PLC so that the light receiving / emitting surface of the optical element and the optical waveguide of the PLC are optically coupled, Alignment between the light receiving / emitting surface and the optical waveguide can be facilitated.

Example 4
FIG. 13 shows a method for joining an optical module and a glass block according to Example 4. The optical element 175 of the optical module 171 is optically coupled to the optical fiber 182 fixed to the glass block 181. The glass block 181 is bonded to the lid 173 of the optical module 171 on the surface including the end surface of the optical fiber 182.

  Reflection occurs at the end surface due to light input / output from the optical fiber 182, and therefore an inclined surface of, for example, 8 degrees is provided on the end surface of the glass block 181 and the lid 173. This inclined surface can prevent return light to the optical element 175 and return light to the optical fiber 182. A thin film filter may be bonded to the surface of the lid 173.

  In addition, when connecting an optical module and PLC directly, in order to prevent the return light which generate | occur | produces in an end surface, you may provide an inclined surface in the end surface of PLC and the lid | cover of an optical module, A thin film filter may be adhered.

(Example 5)
FIG. 14 shows a method for joining an optical module and a glass block according to the fifth embodiment. The glass block 212 fixes three four-core tape type optical fibers 213a to 213c, and is bonded to the three optical modules 201a to 201c on the surface including the end face of the optical fiber 213. The three optical modules 201a to 201c are fixed to the mounting board 212 as shown in FIGS.

  Each of the optical modules 201a to 201c is an optical module in which a plurality of optical elements are integrated. Since the optical modules 201a to 201c are connected to the plurality of optical modules in one block, the mounting space on the mounting board can be reduced. Since the optical modules 201a to 201c are fixed to the mounting board 212 via lead pins, they can be firmly fixed.

  Even when the plurality of optical modules and the PLC are directly connected, the plurality of optical modules may be connected at the end face of the PLC so that the light receiving / emitting surface of the optical element and the optical waveguide are optically coupled. .

(Example 6)
FIG. 15 shows a method for joining an optical module and a glass block according to Example 6. The glass block 232 has the same structure as that of the fifth embodiment. The optical module 221 has 12 optical elements integrated in one housing. All the optical elements can be hermetically sealed, and, as shown in the fifth embodiment, the optical elements can be made smaller than the array of individually hermetically sealed optical elements.

(Optical element arrangement)
In order to ensure the accuracy of alignment between the optical module and the glass block, the optical elements must be accurately arranged inside the optical module. FIG. 16 shows the arrangement of optical elements in the optical module. As described above, the optical module 401 is formed with the metal wiring for connecting the optical element 405 and the electrode pattern on the mounting board. Using this metal wiring, the position of the optical element is determined. When the metal wirings 411a and 411b that are electrically connected to the optical element 405 are formed, for example, marker patterns 412a to 412f are formed. With the marker patterns 412a4 to 12f, the center of the light receiving / emitting surface 404 of the optical element 405 can be always aligned with a certain accuracy and fixed to the housing 402.

  In the present embodiment, alumina-based ceramics is used as the material of the housing, but other ceramics such as silicon carbide, silicon nitride, aluminum nitride, and zirconia may be used. Further, glass such as quartz or sapphire may be used. In addition, the bonding agent for bonding the housing and the lid is not limited to metal solder such as gold tin, gold germanium, and tin lead, and, for example, low melting point glass or brazing agent can be used. The material of the lid is not limited to sapphire described above, and for example, quartz glass, borate glass, or the like can be used. Any material and member can be used as long as airtightness can be secured by the casing and the lid so that the characteristics of the optical element disposed inside the optical module are not deteriorated.

It is a cross-sectional view which shows the method of joining the conventional optical module and PLC directly. It is a perspective view which shows the structure of the conventional optical module. It is a side view which shows the joining method of the optical module concerning 1st Embodiment of this invention, and PLC. It is sectional drawing which shows the structure of the optical module concerning one Embodiment of this invention. It is a perspective view which shows the mounting method of an optical module. It is a figure which shows the other application example of a structure of an optical module. It is a side view which shows the joining method of the optical module concerning 2nd Embodiment of this invention, and PLC. It is a top view which shows the joining method of an optical module and a glass block. It is a top view which shows the structure of the optical transmitter-receiver concerning one Embodiment of this invention. It is a side view which shows the joining method of the optical module concerning Example 1, and a glass block. It is a perspective view which shows the joining method of the optical module concerning Example 2, and a glass block. It is a side view which shows the joining method of the optical module concerning Example 3, and a glass block. It is a side view which shows the joining method of the optical module concerning Example 4, and a glass block. It is a top view which shows the joining method of the optical module concerning Example 5, and a glass block. It is a top view which shows the joining method of the optical module concerning Example 6, and a glass block. It is a top view which shows arrangement | positioning of the optical element in an optical module.

Explanation of symbols

11, 51, 71, 112, 113, 151, 171, 201, 221, 401 Optical module 12, 52, 72, 152, 172, 402 Housing 13, 53, 73, 153, 173 Lids 14, 54, 74, 154, 174, 404 Light emitting / receiving surface 15, 55, 75, 155, 175, 405 Optical element 16, 33, 56, 76 Bonding wire 17, 34, 57, 77, 83, 411, 412 Metal wiring 21 PLC
22 substrate 23 yato 24 optical waveguide 31, 81, 1111, 211, 231 mounting board 32, 82, 92 electrode 58, 78 lead pin 60, 61, 301, 305 connector 62, 92, 121, 122, 162, 182, 213 , 233 Optical fiber 91, 93, 114, 161, 181, 212, 232 Glass block 100 Optical transceiver 131 AWG type optical multiplexer / demultiplexer 132 Peltier element 141 Fiber extra length processing part 164 Convex part 155 Concave part 302 MT ferrule 303 Leaf spring 304 Optical connector

Claims (1)

In an optical module including a housing that is open only on one side, a lid that transmits light and closes and seals the opening of the housing, and an optical element that is fixed with a light emitting / receiving surface facing the lid,
One end face is optically coupled to the plurality of optical waveguides of the planar optical waveguide circuit, as the other end face are respectively optically coupled through the lid and a plurality of light emitting and receiving surface of the arrayed optical element a glass block for holding an array of optical fiber, on the other end surface of the same flat surface of the optical fiber, a glass block is joined to said lid,
A metal wiring electrically connected to the optical element and penetrating from the inside of the housing to the outside of the housing;
A lead pin joined to the metal wiring outside the housing;
An optical module fixed to the mounting board so that a mounting surface of the mounting board and an optical axis of the optical element are parallel to each other.

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