JP2019204890A - Optical assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical subassembly which is small in size and accommodates more semiconductor optical elements, and enables high-speed data transmission and downsizing of an optical module by increasing the number of WDM channels. An optical subassembly (30) houses a plurality of semiconductor optical elements (42) arranged with their optical axes parallel to each other, a submount (44) having the semiconductor optical elements (42) mounted on both main surfaces, and a submount (44). And an outer case 40, which is a casing. The housing is two convex portions or steps provided on the side surface or the bottom surface inside the housing separated in the width direction intersecting the optical axis, and one main surface of the submount 44 has both widthwise ends. The sub-mount support base 54 that abuts on the edge of the sub-mount. [Selection diagram] Fig. 5

Description

  The present invention relates to an optical subassembly.

  In an optical communication system, an optical module that incorporates an optical subassembly (OSA) and converts one of an optical signal and an electrical signal to the other or bidirectionally is used. OSA is a semiconductor optical element that converts between the above optical signal and electric signal, specifically, a light emitting device such as a laser diode (LD) or a light receiving device such as a photodiode (PD) in a housing. It is a stored part.

  In order to cope with downsizing and high functionality of an optical module, an OSA that accommodates a plurality of semiconductor optical elements in one housing and supports multiplexing of signals of a plurality of channels is known (Patent Document 1 below). .

  Further, an optical module including a structure in which four light emitting elements of a CAN package are arranged like the eyes of a dice for miniaturization is known (Patent Document 2 below).

JP, 2006-178218, A JP 2013-232514 A

  In order to further increase the speed of data transmission, there is a demand for OSA that performs wavelength division multiplexing (WDM) of four channels or more, for example, eight channels. Here, as shown in OSA of Patent Document 1, by arranging a plurality of light emitting elements in a line in a direction orthogonal to their optical axes, the light emitting elements are prevented from obstructing the optical path. it can. However, in this configuration, the array width of the semiconductor optical elements increases with an increase in the number of channels, which makes it difficult to reduce the size of the OSA and the optical module using the OSA. Further, as shown in Patent Document 2, the configuration in which a plurality of semiconductor optical elements stored in a CAN-type package are arranged also has a problem that miniaturization of the optical module is limited by the size of the package.

  The present invention has been made to solve the above-described problems, and provides an OSA that is small in size and accommodates more semiconductor optical elements, speeds up data transmission by increasing the number of WDM channels, and an optical module. Can be miniaturized.

  (1) An optical subassembly according to the present invention accommodates a plurality of semiconductor optical elements arranged with their optical axes in parallel, a submount having the semiconductor optical elements mounted on both main surfaces, and the submount. A housing that is separated from each other in a width direction intersecting the optical axis, and is provided with two convex portions or steps provided on a side surface or a bottom surface inside the housing. A sub-mount support is provided that abuts against the edges at both ends in the width direction of one of the main surfaces of the mount.

  (2) In the optical subassembly according to the above (1), the casing is erected on the bottom surface between two submount support bases and abuts on the one main surface of the submount. It can be set as the structure provided with the support | pillar used.

  (3) In the optical subassembly according to (1) and (2), a plurality of the semiconductor optical elements are arranged in the width direction on the one main surface of the submount, and A wiring group connected at one end to the semiconductor optical element is arranged in parallel in the width direction, and an arrangement region of the wiring group on the main surface is located on the one end side of the wiring group and the semiconductor optical element A wide portion having a width corresponding to the arrangement width of the wiring group, and a narrowed portion located on the other end side of the wiring group and having a width narrower than the wide portion, and the submount support base includes the edge portion and the light The dimension in the width direction may be larger in a portion that extends in the axial direction and that faces the narrow portion than a portion that faces the wide portion.

  (4) In the optical subassembly as described in (1) to (3) above, the semiconductor having a lens for condensing output light of the semiconductor optical element and mounted on the one main surface of the submount The lens for the optical element may be installed on the bottom surface, and the lens for the semiconductor optical element mounted on the other main surface may be supported by the submount support.

  According to the present invention, it is possible to obtain an OSA that is small and accommodates more semiconductor optical elements.

It is a perspective view which shows the external appearance of the optical module which concerns on embodiment of this invention. It is a typical top view which shows the structure of the optical transmission apparatus with which the optical module which concerns on embodiment of this invention was mounted | worn. It is a typical side view which shows an optical subassembly, a printed circuit board, and a flexible substrate. It is a typical top view of OSA concerning a 1st embodiment of the present invention. FIG. 5 is a schematic vertical sectional view of the OSA along the line VV in FIG. 4. It is a typical top view of the lower surface side of a submount. It is a typical top view of the exterior case of OSA concerning a 1st embodiment of the present invention. It is a typical vertical sectional view of OSA concerning a 2nd embodiment of the present invention. It is a typical top view of the exterior case of OSA which concerns on the 2nd Embodiment of this invention. It is a typical top view of the exterior case of OSA which concerns on the 3rd Embodiment of this invention. It is a typical top view of OSA which has the characteristics of the 2nd and 3rd embodiment of this invention.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiments, and the repetitive description thereof will be omitted.

[First Embodiment]
FIG. 1 is a perspective view showing an appearance of an optical module 10 according to an embodiment of the present invention. The optical module 10 is an optical transceiver (optical transceiver) having a transmission function and a reception function. The outer shape of the optical module 10 is composed of parts including a case 12, a pull tab 14, and a slider 16.

  FIG. 2 is a schematic top view showing the configuration of the optical transmission device 18 to which the optical module 10 is mounted. A plurality of optical modules 10 are respectively attached to the optical transmission device 18 by electrical connectors 20. The optical transmission device 18 is, for example, a large capacity router or switch. The optical transmission device 18 has a function of an exchange, for example, and is arranged in a base station or the like. The optical transmission device 18 acquires data for reception (electrical signal for reception) from the optical module 10 and uses a driver IC (integrated circuit) 24 mounted on the circuit board 22 to send what data to where. It determines whether to transmit, generates data for transmission (electrical signal for transmission), and transmits the data to the corresponding optical module 10.

  The optical module 10 includes a printed board 26, a flexible board 28, and an optical subassembly (OSA) 30 for converting an optical signal and an electrical signal from at least one to the other. The OSA 30 is connected with an optical fiber 32 for inputting and outputting optical signals.

  Specifically, the OSA 30 is an optical transmission subassembly (Transmitter Optical SubAssembly: TOSA) having an optical transmission function, an optical reception subassembly (Receiver Optical SubAssembly: ROSA) having an optical reception function, and a bidirectional subassembly having an optical transmission / reception function. (Bi-directional Optical SubAssembly: BOSA). For example, the optical module 10 includes two OSAs 30-1 and 30-2.

  FIG. 3 is a schematic side view of the OSA 30, the printed board 26, and the flexible board 28. The printed board 26 is a rigid board having no flexibility, while the flexible board 28 has flexibility and both ends thereof are connected to the printed board 26 and the OSA 30. That is, one end of the wiring formed on the flexible substrate 28 overlaps and is electrically connected to the terminal substrate 34 of the OSA 30, and the other end of the wiring overlaps and electrically connects to the terminal of the printed circuit board 26. Thus, an electrical signal is transmitted between the printed circuit board 26 and the OSA 30. For example, the OSA 30-1 is a TOSA, and an electrical signal is transmitted from the printed circuit board 26 to the OSA 30-1 via the flexible board 28, while the OSA 30-2 is a ROSA, and the electrical signal from the OSA 30-2 is the flexible board 28. To the printed circuit board 26.

  FIG. 4 is a schematic top view of an example of the OSA 30 according to the first embodiment of the present invention. The OSA 30 houses a submount 44 on which a semiconductor optical device 42 is mounted in an outer case 40 that is a casing. Here, as shown in FIGS. 1 and 2, the optical module 10 includes an electrical connector 20 at one end in the longitudinal direction of the elongated case 12, and an optical fiber 32 is connected to the other end. Correspondingly, a relatively small upper limit is imposed on the dimension (width) of the OSA 30 in the short direction of the case 12, and the outer case 40 basically has an elongated shape having the same longitudinal direction as the case 12. . A terminal board 34 connected to the flexible board 28 is provided at one end of the outer case 40 in the longitudinal direction, and an optical fiber connector 48 is provided at the other end.

  Here, for convenience of explanation, an XYZ orthogonal coordinate system is defined for the OSA 30 as a right-hand system with the longitudinal direction of the exterior case 40 as the X axis, the lateral direction as the Y axis, and the height direction as the Z axis. The direction from the terminal board 34 to the optical fiber connector 48 is set to the positive direction of the X axis. The XY plane is the horizontal plane and the Z axis is the vertical direction. The submount 44 is stored in the outer case 40 with the substrate surface horizontal.

  The OSA 30 is used for WDM optical transmission and incorporates a plurality of semiconductor optical elements. For example, in this embodiment, the bit rate of the signal transmitted and received by the optical module 10 is 400 Gbit / s, and the signal is transmitted as an optical signal multiplexed in 8 wavelengths. In other words, the optical module 10 transmits and receives signals of 8 channels of 50 Gbit / s. Correspondingly, the OSA 30 incorporates eight semiconductor optical elements 42. The plurality of semiconductor optical elements 42 are arranged on the submount 44 with the optical axes parallel. In the present embodiment, the optical axis of each semiconductor optical element 42 is set parallel to the X axis.

  Incidentally, the semiconductor optical element 42 is an optical conversion element that converts an optical signal or an electrical signal from one to the other. Specifically, the OSA 30-1 that is a TOSA has a light-emitting element such as a laser diode as an optical conversion element that converts an electrical signal into an optical signal for each of the eight channels, and the OSA 30-2 that is a ROSA has an eight channel. For each, a light receiving element such as a photodiode is provided as a light converting element for converting an optical signal into an electric signal.

  FIG. 4 illustrates an OSA 30-1 that is a TOSA. In addition to the submount 44, the condenser lens 50 and the optical multiplexer 52 are housed in the exterior case 40. The condenser lens 50 is disposed on the optical axis of the optical signal output from each of the eight light emitting elements, converts the optical signal into collimated light, and inputs the collimated light to the optical multiplexer 52. The optical multiplexer 52 combines the optical signals output from each of the eight light emitting elements to generate one optical signal transmitted through the optical fiber 32. The optical multiplexer 52 is configured by a known technique using, for example, a prism or a mirror.

  With regard to the arrangement of the plurality of semiconductor optical elements 42, it is required that each semiconductor optical element 42 does not become an obstacle to an optical signal that is emitted from another semiconductor optical element 42 or incident on the semiconductor optical element 42. For this purpose, for example, a plurality of semiconductor optical elements 42 may be arranged in a direction intersecting the optical axis. In the present embodiment, the plurality of semiconductor optical elements 42 are mounted separately on both main surfaces (upper surface and lower surface) of the substrate constituting the submount 44, and the plurality of semiconductor optical elements 42 mounted on each main surface are mounted on the Y axis. Arranged in a row in the direction. Thus, by arranging the semiconductor optical elements 42 separately on both sides of the submount 44, the lateral width of the OSA 30 can be made smaller than when all the semiconductor optical elements 42 are arranged on one side of the submount 44. As a result, the horizontal width of the optical module 10 can be reduced.

  In particular, the difference between the number of semiconductor optical elements 42 arranged on one main surface of the submount 44 and the number of semiconductor optical elements 42 arranged on the other main surface is reduced, that is, the number of semiconductor optical elements 42 arranged on both surfaces is reduced. The horizontal width of the OSA 30 can be suitably reduced by equalizing the numbers. Therefore, in this embodiment, the same number is arranged on both surfaces of the submount 44.

  FIG. 5 is a schematic vertical sectional view of the OSA 30 taken along the line VV in FIG. As described above, the eight semiconductor optical elements 42 are separately arranged on the upper surface and the lower surface of the submount 44, and four semiconductor optical elements 42-1 to 42-4 are disposed on the upper surface, and four semiconductor optical elements are disposed on the lower surface. The optical elements 42-5 to 42-8 are arranged in the Y-axis direction.

  A plan view of the upper surface side of the submount 44 is shown in FIG. 4, and FIG. 6 shows a plan view of the lower surface side of the submount 44. In the present embodiment, the layout on the main surface of the submount 44 is basically common between the upper surface side and the lower surface side. Specifically, the semiconductor optical element 42 is arranged near the side of the condensing lens 50 side of the rectangular side of the submount 44, and two wirings 56 for each semiconductor optical element 42 are connected to the semiconductor optical element 42 and the terminal. It extends in the X direction between the substrate 34 and the side.

  The wiring 56 on the submount 44 and the wiring 58 on the terminal substrate 34 are electrically connected via a feedthrough (not shown) penetrating the side wall of the exterior case 40. Note that wiring 58 connected to the semiconductor optical element 42 disposed on the upper surface side of the submount 44 is shown on the upper surface of the terminal substrate 34 appearing in FIG. The wiring 58 to be connected can be disposed on the lower surface of the terminal board 34. In this case, the wiring 58 on the lower surface side is drawn out to the upper surface side of the terminal substrate 34 through vias and is electrically connected to the wiring of the flexible substrate 28 connected to the upper surface of the terminal substrate 34 as shown in FIG. . Further, vias may be provided in the submount 44 and the wiring of the semiconductor optical element 42 on the lower surface side of the submount 44 may be drawn to the upper surface side. In this case, the wiring 58 for the semiconductor optical elements 42 on both surfaces of the submount 44 is provided. All may be arranged on the upper surface of the terminal board 34.

  As shown in FIG. 5, the submount 44 is supported at a predetermined position in the Z-axis direction by a submount support base 54 provided inside the exterior case 40. The submount support base 54 is two convex portions or steps provided on the inner side surface or bottom surface of the exterior case 40 separated in the Y-axis direction. Of the lower surface that is one main surface of the submount 44, Y The submount 44 is supported by the edges at both ends in the axial direction. In the example shown in FIG. 5, the submount support base 54 is a step provided on the inner side surface of the outer case 40, and a portion below the step in the side surface of the outer case 40 is positioned inside a portion above the step. Then, the lower surface of the submount 44 abuts on a horizontal step surface connecting the upper side surface and the lower side surface. Note that the semiconductor optical element 42 and the wiring 56 are not disposed on the lower surface edge portion of the submount 44 with which the submount support base 54 abuts.

  The outer case 40 is made of, for example, a material having a high thermal conductivity such as a metal. The submount 44 is made of an insulating material having high thermal conductivity, and is made of a ceramic material such as aluminum nitride or aluminum oxide. As described above, the exterior case 40 and the submount 44 are formed of a material having high thermal conductivity, and are brought into contact with each other by the submount support base 54, whereby heat generated in the semiconductor optical element 42 is suitably radiated to the outside of the OSA 30. Can be made. Note that the submount 44 can be bonded to the submount support 54, and in this case, the bonding member is also preferably made of a material having high thermal conductivity.

  The exterior case 40 can be configured by a main body having an opening at the top and a lid 40u that closes the opening. In this configuration, the submount 44 and the like are housed in the recess of the main body of the exterior case 40 from the opening, and then the opening of the main body is sealed with the lid 40u.

The submount support 54 may be shaped like a shelf that protrudes horizontally from the inner side surface (surface parallel to the XZ plane) of the outer case 40, and the edge of the submount 44 may be placed on the horizontal surface of the shelf. it can. The submount support 54 is shaped like a column or wall protruding upward from the inner bottom surface (surface parallel to the XY plane) of the outer case 40, and the edge of the submount 44 is placed on a horizontal plane provided on the top. It can also be a structure.
The submount 44 is suspended in the outer case 40 by the submount support 54, and the position of the semiconductor optical element 42 in the Z-axis direction can be set, for example, at the center of the outer case 40. The element 42 can be arranged away from the bottom surface of the outer case 40.

  FIG. 7 is a schematic top view of the outer case 40 with the lid 40u removed, and the plan shape of the submount support base 54 is shown. In the example shown in FIG. 7, the submount support base 54 is formed on a straight line along the side surface parallel to the X axis of the exterior case 40, and the width of the step surface of the submount support base 54 is basically a constant value. is there. That is, even if the position in the X-axis direction changes, the dimension in the Y-axis direction of the step surface does not change.

  Further, the submount support base 54 can be configured to abut only at a part in the X axis direction among the edges of both ends of the submount 44 in the Y axis direction. As shown in FIG. 4, 54 is brought into contact with the entire edge in the X-axis direction. Thereby, the contact area between the submount 44 and the submount support base 54 can be increased, and the heat conduction efficiency from the submount 44 to the exterior case 40 can be increased.

  Further, the submount support base 54 of FIG. 7 extends to the position of the condenser lens 50 as shown in FIG. For example, the condenser lens 50 can be a lens array in which lenses corresponding to the four semiconductor optical elements 42 on the upper surface of the submount 44 and lenses corresponding to the four semiconductor optical elements 42 on the lower surface are integrally formed. . The submount support 54 is brought into contact with the edges of both ends in the Y-axis direction of the condenser lens 50 constituting the lens array, and supports the condenser lens 50 at a height corresponding to the submount 44. The condensing lens 50 can also be configured separately from a lens array corresponding to the four semiconductor optical elements 42 on the upper surface of the submount 44 and a lens array corresponding to the four semiconductor optical elements 42 on the lower surface. In this case, the condenser lens 50 that forms the upper lens array is supported by the submount support base 54, and the condenser lens 50 that forms the lower lens array can be installed on the bottom surface of the exterior case 40.

  As described above, the outer case 40 having the structure in which the submount support base 54 is arranged separately in the Y-axis direction and the submount 44 is supported by the lower surface edge of the submount 44 is located at the center of the lower surface in the Y-axis direction. The submount 44 in which the semiconductor optical element 42 and the wiring 56 are arranged can be accommodated. In other words, the outer case 40 can accommodate the submount 44 in which the semiconductor optical elements 42 are arranged on both sides, thereby enabling high-speed data transmission due to an increase in the number of WDM channels and downsizing of the OSA 30. Become.

[Second Embodiment]
On the other hand, as a structure for supporting the submount 44, in addition to the submount support base 54, it is also possible to provide a column that abuts against a gap in the layout of the semiconductor optical device 42 and the wiring 56 on the lower surface of the submount 44.

  The OSA 30 according to the second embodiment of the present invention includes the support column in the outer case 40A. FIG. 8 is a schematic vertical sectional view of the OSA 30 according to the second embodiment. FIG. 8 shows a cross section along the XY plane, which should be compared with FIG. 5 of the first embodiment. As shown in FIG. 8, the outer case 40 </ b> A includes a column 70 that is erected on the bottom surface between the two submount support bases 54 and is in contact with the lower surface of the submount 44 </ b> A.

  FIG. 9 is a schematic top view of the outer case 40A shown in FIG. 8, and shows a state where the lid 40u is removed, as in FIG. FIG. 8 shows a cross section taken along line VIII-VIII in FIG. For example, the column 70 is provided in the center of the exterior case 40A in the Y-axis direction, and the submount is provided at a position where the semiconductor optical element 42 and the wiring 56 for four channels provided on the lower surface of the submount 44A are divided into two channels. 44A. Specifically, in the example shown in FIGS. 8 and 9, two semiconductor optical elements 42-6 and 42-7 in the center among the four semiconductor optical elements 42-5 to 42-8 arranged in the Y-axis direction. The horizontal surface of the upper end of the support column 70 is brought into contact with each other.

  Similar to the submount support base 54, the column 70 has a function of supporting the submount 44A and a function of radiating heat from the submount 44A. It should be noted that the submount 44A and the column 70 and the submount support base 54 can be bonded in the same manner as the submount 44 and the submount support base 54 described above.

[Third Embodiment]
In the second embodiment, by providing the column 70, the contact area between the outer case 40A and the submount 44A can be increased, and the heat dissipation efficiency can be improved. In this regard, the heat dissipation efficiency can also be improved by increasing the contact area between the submount support base 54 and the submount 44. The outer case 40B of the OSA 30 according to the third embodiment of the present invention is formed such that the size of a part of the submount support base 54B is larger than the other part, and the submount support base 54B and the submount 44B The contact area is increased.

  FIG. 10 is a schematic top view of the outer case 40B of the present embodiment, and shows a state in which the lid 40u is removed as in FIGS. Regarding the dimension in the Y-axis direction, the end portion 54w on the terminal board 34 side of the submount support base 54B is larger than the other part of the submount support base 54B.

  As described in the first embodiment, a plurality of semiconductor optical elements 42 are arranged in the Y-axis direction on both main surfaces of the submount 44B, and one end is connected to the plurality of semiconductor optical elements. A wiring group consisting of the wirings 56 is arranged in parallel in the Y-axis direction. In the present embodiment, the width of the arrangement region of the wiring group on the lower surface of the submount 44B is narrowed on the terminal substrate 34 side so that the wide end portion 54w of the submount support base 54B does not contact the wiring 56.

  The characteristic configuration of this embodiment can be used together with the characteristic configuration of the second embodiment, and FIG. 11 is a schematic top view of the OSA 30 showing an example of the configuration. The features of the present embodiment will be described more specifically with reference to FIG. FIG. 11 shows the outer case 40C and the submount 44C, and other components such as the condenser lens 50 and the optical multiplexer 52 are not shown.

  The outer case 40C has a submount support base 54B similar to the outer case 40B of FIG. That is, the submount support base 54B of the outer case 40C has a wide end portion 54w on the terminal board 34 side, like the outer case 40B shown in FIG. The outer case 40C has a support column 70 at the center in the Y-axis direction.

  FIG. 11 shows the layout of the semiconductor optical device 42 and the wiring 56 on the upper surface of the submount 44C. The layout of the semiconductor optical device 42 and the wiring 56 on the lower surface of the submount 44C is the same as that of the upper surface.

  The arrangement region of the wiring group including the wirings 56 is located on the optical fiber connector 48 side and has a wide portion 74 having a width corresponding to the arrangement width of the semiconductor optical elements 42, and is located on the terminal substrate 34 side and wider than the wide portion 74. Including a narrow constriction 72. On the other hand, the submount support base 54B extending in the X-axis direction has a wide end portion 54w that faces the narrowed portion 72. That is, the submount support base 54 </ b> B has a larger dimension in the width direction at the portion facing the narrowed portion 72 than at the portion facing the wide portion 74. Incidentally, the narrowed portion 72 of the wiring group is formed by narrowing the width and arrangement interval of the wiring 56 from the wide portion 74.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible. For example, the configuration described in the embodiment can be replaced with substantially the same configuration, a configuration that exhibits the same operational effects, or a configuration that can achieve the same purpose.

  10 optical modules, 12 cases, 14 pull tabs, 16 sliders, 18 optical transmission devices, 20 electrical connectors, 22 circuit boards, 24 driver ICs, 26 printed boards, 28 flexible boards, 30 optical subassemblies (OSAs), 32 optical fibers, 34 terminal board, 40 outer case, 42 semiconductor optical element, 44 submount, 48 optical fiber connector, 50 condenser lens, 52 optical multiplexer, 54 submount support base, 56, 58 wiring, 70 strut, 72 constriction, 74 Wide part.

Claims (4)

A plurality of semiconductor optical elements arranged in parallel with the optical axis;
A submount in which the semiconductor optical element is mounted on both main surfaces;
A housing for housing the submount,
The casing is two convex portions or steps provided on a side surface or a bottom surface inside the casing separated in a width direction intersecting the optical axis, and one of the main surfaces of the submount. Comprising a submount support that is brought into contact with the edges at both ends in the width direction;
An optical subassembly featuring. The optical subassembly of claim 1, wherein
The optical housing is provided with a support column that is erected on the bottom surface between the two submount support bases and is in contact with the one main surface of the submount. The optical subassembly according to claim 1 or claim 2,
A plurality of the semiconductor optical elements are arranged in the width direction on the one main surface of the submount, and a wiring group connected to one end of the plurality of semiconductor optical elements is arranged in parallel in the width direction. Arranged,
The arrangement region of the wiring group on the main surface is located on the one end side of the wiring group and has a wide portion having a width corresponding to the arrangement width of the semiconductor optical elements, and on the other end side of the wiring group. Including a narrowed portion narrower than the wide portion,
The submount support base extends in the optical axis direction together with the edge portion, and has a larger size in the width direction at a portion facing the narrowed portion than a portion facing the wide portion,
An optical subassembly featuring. The optical subassembly according to any one of claims 1 to 3,
A lens for collecting the output light of the semiconductor optical element;
The lens for the semiconductor optical element mounted on the one main surface of the submount is installed on the bottom surface, and the lens for the semiconductor optical element mounted on the other main surface is provided by the submount support. Being supported,
An optical subassembly featuring.

Images