JP2003066288A - Optical module and its assembling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a module of a high-speed surface type optical element which has high coupling efficiency, is compact, and has high productivity. SOLUTION: A method for assembling an optical module provided with an optical fiber 9, an optical lens 6, a package 5, a mirror 8 which turns the optical path in the orthogonal direction, and a high frequency photoelectronic element 2 which inputs and outputs an optical signal in the perpendicular direction of an element substrate includes a process in which the optical lens 6 is fixed to the package 5 then mirror 8 or a mirror holder 8' to which the mirror 8 is preliminarily fixed is shifted in the horizontal direction on the mounting face of the package 5 and is aligned so as to obtain the most suitable optical coupling state and is fixed to the package 5 by welding or an adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical module and its assembling method. Specifically, in an optical module used for optical communication or measurement, a photodiode (PD) for high-speed signal processing or a surface emitting laser diode (vertical cavity) is used.
It is a technology relating to modularization of a surface-type optical element such as an optical surface-emitting laser diode (VCSEL).

[0002]

2. Description of the Related Art FIG. 3 is a structural view of a conventional high-speed PD module, (a) is a top view, (b) is a cross-sectional view, and FIG. 4 is an explanation viewed from the optical axis direction to show the welded portion. It is a figure. Here, 1 is a planar PD element, 2 is a ceramic high-frequency wiring board, 3 is a high-frequency connector, 4 is a metal submount, 5 is a package, 6 is an aspherical lens, 7 is a lens holder, 8 is a mirror, 9 Is an optical fiber, 10 is a fiber holder, 11 is a lens column, and 12 is a lid for hermetic sealing.

To assemble this, first, the high-frequency wiring board 2 is fixed to the submount 4 with solder such as gold tin / gold germanium or an adhesive. Next, the PD element 1 is fixed near the high-frequency wiring board 2 with gold tin solder or an adhesive. In this state, the element 1 is electrically checked to confirm whether or not there is any deterioration during mounting. Subsequently, the mirror 8 (actually, the mirror is fixed in a state of being mounted on the mirror holder as in the embodiment described later, but omitted in the drawing because it is complicated) is sub-mounted by an adhesive or YAG laser welding. Fix at 4.

After that, light is input from the outside and the lens 6 is aligned while measuring the light receiving current of the PD element 1.
The YAG laser is welded and fixed to the submount 4 and the lens column 11 formed on the submount 4 via the lens holder 7. Then, the submount 4 is fixed with solder or an adhesive at a position where the electric wiring board 2 on the submount 4 and the electric wiring board 2 installed beforehand on the high frequency connector side of the package 5 face each other.

Then, the wiring boards 2 and the grounds of the package 5 and the submount 4 are electrically connected to each other by a gold ribbon or a silver paste. After the element 1 is electrically checked, the lid 12 for hermetic sealing is fixed to the package 5 by resistance welding or an adhesive to hermetically seal it. Finally, the fiber 9 is aligned on the outside of the package 5, and the fiber 9 and the fiber holder 10 are placed at a position where the received light current is optimum.
This is completed by welding and fixing it to the package 5 with an AG laser. Here, the expression “the received light current is optimum” is because the maximum value is not the optimum value depending on the application of the module.

[0006]

In the conventional method of assembling the optical module described above, the submount 4 is thicker than the lens radius in order to adjust and fix the lens 6 while stably holding the submount 4. It became mandatory and the package height had to be increased accordingly. In particular, in the case of a surface-type element, in order to insert the mirror 8 between the lens 6 and the element 1, a lens 6 having a long working distance and thus a large outer diameter is necessary, which is a factor that cannot reduce the thickness of the module. Was becoming.

Further, in the structure using the submount 4, high dimensional accuracy is required in order to make the heights of the high-frequency wiring board 2 of the submount 4 and the package 5 uniform, which causes a cost increase and a yield reduction. On the other hand, there is also a module in which an element is mounted in a package in advance and the lens is aligned and fixed to the element in the package. However, in that case, YAG will be on the package wall.
It was inevitable to make a wide package so that the laser beam could not be shielded, and it was difficult to miniaturize it.

Further, since the welded portion of the lens and the package is limited to a place where the lens can be shot from above, in the example of FIG. 4,
Only the upper side of the lens holder can be welded, the lens is not fixed properly, and in the high-speed element with a small light receiving diameter and severe tolerance, problems such as easy misalignment of the optical axis occur, which is a reliability issue. Was left. An object of the present invention is to provide a compact high-speed planar optical element module with high coupling efficiency with high productivity.

[0009]

An optical module assembling method according to claim 1 of the present invention which solves such an object is an optical fiber, an optical lens, a package, and a mirror for bending an optical path in an orthogonal direction. And a high-frequency optoelectronic device for inputting and outputting an optical signal in the vertical direction of the device substrate, the optical lens is first fixed to the package, and then the mirror or the mirror is fixed in advance. The method may further include a step of horizontally shifting the mirror holder on a mounting surface of the package, aligning the mirror holder so as to obtain an optimal optical coupling state, and fixing the mirror holder to the package with welding or an adhesive.

An optical module according to a second aspect of the present invention which solves the above object is an optical fiber, an optical lens, a package, a mirror for bending an optical path in an orthogonal direction, and an optical signal in a direction perpendicular to an element substrate. In the optical module including a high-frequency optoelectronic device for inputting and outputting, the optical lens is fixed in advance to the package, and then the mirror or a mirror holder in which the mirror is fixed in advance is horizontally mounted on the mounting surface of the package. It is characterized in that it is displaced, aligned so as to obtain an optimum optical coupling state, and fixed to the package by welding or an adhesive.

[Operation] According to the present invention, a compact high-speed optical module having high coupling efficiency can be realized with high productivity.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] FIG. 1 shows a first embodiment of the present invention.
3A and 3B are views for explaining the embodiment of FIG. Here, 1 is a surface type PD element, 2 is a ceramic high-frequency wiring board, 3 is a high-frequency connector, 5 is a package, 6 is an aspherical lens, 8'is a mirror holder, 9 is an optical fiber, 10 is a fiber holder, 1
2 is a lid for hermetically sealing.

To assemble this, first, the aspherical lens 6 is fixed to the package 5 by means such as brazing, welding and press fitting. Next, the PD element 1 is flip-chip mounted and fixed on the upper surface of the high-frequency wiring board 2 with gold tin solder, an adhesive, or the like. Here, after the PD element 1 is electrically checked, the substrate 2 is fixed to a predetermined position of the package 5 with gold tin solder, an adhesive or the like. Then, the wiring boards 2 are electrically connected to each other with a gold ribbon.

Then, an optical signal is input from an external fiber,
While measuring the received light current of the PD element 1, the position of the mirror holder 8'having the mirror mounted thereon is aligned with the mounting surface of the package 5 so that the mirror holder 8'is fixed to the package 5 by laser welding from above. . afterwards,
The lid 12 for airtight sealing is fixed to the package 5 by resistance welding and hermetically sealed. Finally, the fiber 9 is aligned on the outside of the package 5, and the fiber 9 and the fiber holder 10 are fixed by YAG laser welding at a position where the received light current is optimum.

In the present embodiment, in order to correct the mounting position deviation of the PD element 1, the position of the mirror can be adjusted only in the horizontal direction with respect to the package bottom surface, and the fixing can be performed by welding from almost directly above. No need to unfold. Further, since the mirror holder 8'and the package 5 are always in contact with each other, it is possible to fix them by resistance welding instead of laser welding. If it is not used under such severe conditions, sufficient stability can be obtained even if it is fixed with an adhesive.

Although the optical distance between the lens 6 and the element 1 cannot be basically adjusted by this adjusting method, the mounting accuracy of the element 1 is generally within several tens of μm, and the mounting accuracy of the substrate 2 and the lens 6 is included. Since it is not so difficult to suppress the error to about 100 μm, in general, adjustment on the fiber side can sufficiently cover the error. Further, when it is absolutely necessary to make a fine adjustment of 100 μm or less, it is possible to deal with it by preparing several kinds of mirror holders 8 ′ having different mirror mounting angles.

In this embodiment, since the lens 6 and the package 5 can be integrated in advance, the package height can be suppressed, and the lens can be fixed in a batch process, so that improvement in productivity and cost reduction can be expected. Although flip-chip mounting of the element is not an absolute element, it is advantageous in terms of transmission characteristics in the high-speed optical element that is the aim of the present invention, and an electrical check after mounting the element is also performed in the package. There is an advantage that it is easier than that, and the disposal cost when a defective product comes out can be reduced.

[Embodiment 2] FIG. 2 is a view for explaining a second embodiment of the present invention, in which (a) is a top view and (b) is a top view.
Is a sectional view. Here, 1 is a surface-type PD element, 2 is a ceramic high-frequency wiring board, 3'is a via hole formed in the package, 5'is a ceramic package, 6 is an aspherical lens, 8'is a mirror holder, and 9 is optical. Fiber, 1
Reference numeral 0 is a fiber holder, 12 is a lid for hermetically sealing, and 13 is a metal ring for welding.

In this embodiment, the ceramic package 5'is used, and the lens 6 is also integrally formed inside by high temperature solder, low melting point glass or the like at the time of manufacturing the package. In order to fix the fiber 9 by welding, the metal ring 13 is also integrally manufactured on the end surface of the package 5 ′ by a method such as brazing. The high-frequency signal output is output to the bottom surface via the via hole 3 ', and is directly wired to the board on which the optical module is mounted.

As for the assembling method, the lens fixing can be omitted,
Basically, it is the same as the first embodiment. In this embodiment, further miniaturization and economy can be expected, and it is considered to be suitable for mass production. If a high frequency wiring circuit 2 is also formed in the package 5'using a material having a low high frequency loss such as alumina as a package material, the wiring board as a component can be omitted. It should be noted that, in the above-described embodiment, the PD element 1 is described as a target, but a VC having a similar module configuration is used.
Any surface type optical device such as SEL can be generally applied.

As described above, the present invention relates to modularization of a surface-type optical element such as a photodiode or a surface-emitting laser for high-speed signal processing. As shown in FIGS. 3 and 4, the conventional optical module is configured by incorporating the submount 4 on which the lens holder 7 is mounted into the package 5, and thus the size and the number of parts are large and the cost is high. It contained problems. Also,
When the lens holder 7 is fixed by laser welding, the range in which the laser light can be irradiated is limited, so that the lens cannot be fixed sufficiently and the alignment accuracy of the optical axis deteriorates.

On the other hand, in the present invention, as shown in FIG. 1, the lens is fixed in advance without using the submount, and the position of the mirror holder 8'is optimally in the optically coupled state. After adjusting as described above, it is fixed by welding or adhesion. Therefore, in the present invention, since the submount is not used, the effect of reducing the size is remarkable, the number of parts and the number of assembling steps are reduced, and the cost can be reduced.

[0023]

As described above in detail with reference to the embodiments, according to the present invention, the optical module can be miniaturized, the number of parts can be reduced, and the productivity can be improved, so that the cost can be reduced. Is possible.

[Brief description of drawings]

FIG. 1 is a high-speed P illustrating a first embodiment of the present invention.
It is a block diagram of a D element module, the figure (a) is a top view and the figure (b) is a sectional view.

FIG. 2 is a high-speed P illustrating a second embodiment of the present invention.
It is a block diagram of a D element module, the figure (a) is a top view and the figure (b) is a sectional view.

3A and 3B are configuration diagrams of a conventional high-speed PD element module, in which FIG. 3A is a top view and FIG. 3B is a sectional view.

FIG. 4 is an explanatory view seen from the optical axis direction for showing a welded portion of a conventional high-speed PD element module.

[Explanation of symbols]

1 PD element 2 High frequency wiring board 3 high frequency connector 4 submount 5 packages 6 Aspherical lens (with metal frame) 7 lens holder 8 mirror 8'mirror holder 9 optical fiber 10 Fiber holder 11 lens support 12 lid

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomoshi Furuta             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 2H037 BA03 BA12 CA10 CA15 CA38                       DA02 DA06 DA16 DA18                 5F073 AB27 AB28 BA02 DA35 FA07                       FA08 FA16 FA21 FA30                 5F088 BA15 BA16 BB01 BB06 CB20                       JA12 JA14 JA20

Claims (2)

[Claims] 1. An assembly of an optical module comprising an optical fiber, an optical lens, a package, a mirror for bending an optical path in an orthogonal direction, and a high-frequency optoelectronic element for inputting and outputting an optical signal in a direction perpendicular to an element substrate. In the method, first, the optical lens is fixed to the package, and then the mirror or a mirror holder to which the mirror is previously fixed is horizontally shifted on a mounting surface of the package,
A method of assembling an optical module, comprising the steps of aligning so as to obtain an optimum optical coupling state and fixing the package to the package with welding or an adhesive. 2. An optical module comprising an optical fiber, an optical lens, a package, a mirror for bending an optical path in an orthogonal direction, and a high-frequency optoelectronic element for inputting and outputting an optical signal in a direction perpendicular to an element substrate, The optical lens is previously fixed to the package, and then the mirror or the mirror holder to which the mirror is previously fixed is horizontally shifted on the mounting surface of the package, and aligned so as to obtain an optimum optical coupling state. An optical module characterized by being fixed to the package by welding or an adhesive.