Electro-optical module
The electro-optical module has a substrate with a mounting surface that is free from depressions. A surface-mounted component unit is disosed on the mounting surface. The component unit contains as integral components an electro-optical component and a lens which are aligned directly with one another. The surface serves, furthermore, as a reference plane for assembling a receptacle for an optical fiber plug.
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This is a continuation of copending International Application PCT/DE97/01041, filed May 16, 1997, which designated the United States.
BACKGROUND OF THE INVENTION FIELD OF THE INVENTIONThe invention is in the field of electro-optical structures for optical systems. In particular, the invention pertains to an electro-optical module having an electro-optical component and having a receptacle for an optical fiber plug, which are arranged on a single surface of a substrate, and having a lens arranged in the optical path between the component and the receptacle.
Such modules are utilized in the transmission of signals by means of optical fibers, and contain at least one component which comprises an electro-optical transducer. An electro-optical transducer serves to convert optical signals into electrical signals and/or, conversely, to convert electrical signals into optical signals.
A module of the above-mentioned type has become known from U.S. Pat. No. 5,337,398 (European EP 0 600 645 A1) to Benzoni et al. That module comprises two electro-optical components (laser diode and photodiode) which are positioned on metal surfaces (pads) precisely placed on a silicon substrate by means of a reheatable solder. When the solder is subsequently reheated (i.e., reflow), the components are centered with respect to the pads because of the surface tension of the liquefied solder.
A multiplicity of alignment depressions are produced in the silicon material by etching into the surroundings of the pads, and thus in the surroundings of the electro-optical components. It is possible to insert into the depressions aligning elements—for example, aligning balls—which cooperate with corresponding aligning depressions in a separate carrier which is to be aligned precisely via the respective electro-optical component.
The carrier can carry a lens provided in the beam path between the component and a receptacle for an optical fiber plug, or can align the receptacle directly with respect to the components.
If the individual parts are produced with extreme precision, in particular the carrier, the bipartite aligning depressions and, if appropriate, the lens and/or the receptacle for the optical fiber plug, then the prior art module renders it possible to dispense with an active adjustment of the receptacle with respect to the electro-optical component. The height of the carrier and, if applicable, the lens diameter are, however, design variables, which exert a considerable influence on the relative position of the receptacle and/or of the optical fiber plug with respect to the electro-optical component in the Z-direction. The Z-direction is the orientation of the optical fiber or the direction of the beam path. The direct fastening, addressed in U.S. Pat. No. 5,337,398 (EP 0 600 645 A1), of the receptacle on the substrate surface can then lead to component strains when the geometry of the carrier and, if applicable, of the lens does not permit the actual positioning of the receptacle in the Z-direction to be connected directly without strain to the substrate.
SUMMARY OF THE INVENTIONIt is accordingly an object of the invention to provide an electro-optical module, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which has highly precise, reproducible coupling geometries in the Z-direction with as few individual parts as possible.
With the foregoing and other objects in view there is provided, in accordance with the invention, an electro-optical module, comprising:
-
- a substrate formed with a mounting surface;
- a receptacle for an optical fiber plug defining a beam path substantially perpendicular to the mounting surface; and
- an integrated component unit mounted on the mounting surface, the component unit comprising an electro-optical component and a lens directly aligned with one another in the beam path between the electro-optical component and the receptacle. It is advantageous, thereby, that it is no longer necessary to provide the mounting surface with aligning structures.
In other words, the objects of the invention are satisfied with an electro-optical module of the type mentioned in the introduction that has a mounting surface free of aligning structures, and wherein the electro-optical component and the lens are aligned directly with one another, forming an integrated component unit that can be assembled on the surface.
From a production engineering standpoint, a substantial advantage of the invention consists in that—apart from conductor tracks and metallizations—the surface of the substrate can remain unstructured and free from depressions. Consequently, the selection of the material for the substrate is not dependent on special structuring properties—such as, for example, in the case of the silicon substrate to be used in accordance with the above-mentioned U.S. Pat. No. 5,337,398. Rather, the substrate (for example, printed circuit board) can be selected in an optimum fashion in accordance with aspects of handling, production engineering and, in particular, costs.
A further substantial advantage of the invention consists in the fact that the surface-mountable component unit formed by the electro-optical component and the lens can be produced and tested in advance in a highly precise fashion. Subsequent assembly, affected by tolerances, of a lens support via an electro-optical component which is to be assembled in advance on the substrate is not required with the novel module. Consequently, both production engineering is simplified and an additional tolerance variable is excluded. The component unit can preferably have metallic surfaces for direct electrical contact with the substrate. The reproducible accuracy in the Z-direction is determined only by the component unit, while the substrate thickness is quite irrelevant in this regard.
In accordance with an added feature of the invention, the receptacle is disposed so as not to touch the component unit, the receptacle making contact with and being connected substantially only to the mounting surface of the substrate. This feature permits an embodiment that is completely free from strain and is scarcely stressed in the case of temperature variations.
In accordance with an additional feature of the invention, there is provided an electronic circuit on a surface of the substrate that is averted from the receptacle. Consequently, an electronic drive circuit (in the state of transmission) or a receiving or amplifying circuit can be arranged very near to the component. The signal paths are thereby shortened, and the vulnerability of the system is reduced.
In accordance with another feature of the invention, a cap is attached directly to the mounting surface of the substrate for electrically shielding the component unit. This feature is particularly important to further improve the radiofrequency properties and the insensitivity to external disturbances.
In accordance with a concomitant feature of the invention, the substrate forms a part of a rigid-flexible-rigid circuit carrier.
The design engineering is thereby simplified. Mechanical and electrical connections are united by design in the flexible part of the rigid-flexible-rigid circuit carrier.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electro-optical module, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawing in detail and first, particularly, to
The top side 22, remote from the substrate, of the component unit 20 is shaped as a lens (compare
As
Referring again to
In the described module, although there may be a need to adjust the receptacle 12 with respect to the component 3 in the X-Y direction—that is to say in the plane perpendicular to the Z-direction—this adjustment is not a problem, because of the smooth surface 2, of planar construction, of the printed circuit board. The module offers the substantial advantage that only comparatively few tolerances influence the accuracy in the Z-direction, with the result that in this regard no adjusting or correcting measures remain necessary after assembly. A further advantage of the module is that the component unit 20 and the receptacle 12 are aligned in the Z-direction with the same reference surface—specifically, the surface 2. The accuracy in the Z-direction is thereby essentially determined only by a single part, i.e., the component unit 20. The substrate thickness, on the other hand, has no bearing. The evaluation or drive electronics for the component 3 can advantageously be arranged on the rear side of the substrate. Favorable radio-frequency properties and a high insensitivity to external disturbances are ensured by short conductor tracks 7 and direct plated-through holes to the component unit 20. The insensitivity is further increased by the cap 60, with which contact is correspondingly made.
With reference to
Claims
1. An electro-optical module, comprising:
- a substrate formed with a mounting surface;
- a receptacle for an optical fiber plug defining a beam path substantially perpendicular to said mounting surface; and
- an integrated component unit mounted on said mounting surface, said component unit comprising an electro-optical component and a lens directly aligned with one another in the beam path between said electro-optical component and said receptacle.
2. The electro-optical module according to claim 1 7, wherein said mounting surface is substantially free from aligning structures.
3. The electro-optical module according to claim 1 7, wherein the receptacle is disposed so as not to touch said component unit, said receptacle making contact with and being connected substantially only to said mounting surface of said substrate.
4. The electro-optical module according to claim 1 7, wherein said substrate has a second surface on a side thereof averted from said receptacle, and including an electronic circuit carried on said second surface.
5. The electro-optical module according to claim 1 7, which further comprises a cap attached directly to said mounting surface of said substrate for electrically shielding said component unit.
6. The A rigid-flexible-rigid circuit carrier comprising:
- the electro-optical module according to claim 1 7, wherein said substrate forms a part of a rigid-flexible-rigid circuit carrier first rigid part;
- a flexible part comprising flexible conductors connected to the substrate; and
- a second rigid part comprising a printed circuit board.
7. An electro-optical module, comprising:
- a substrate formed with a mounting surface;
- a receptacle for an optical fiber plug defining a beam path substantially perpendicular to said mounting surface; and
- an integrated component unit mounted on said mounting surface, said integrated component unit comprising: a solid body defining at least first and second surfaces; an electro-optical component mounted on the first surface; and a lens formed on the second surface, wherein the lens and the electro-optical component are directly aligned with one another in the beam path between said electro-optical component and said receptacle, wherein said first surface is opposite said second surface.
8. The electro-optical module according to claim 7, wherein said first surface is substantially parallel to said second surface.
9. The electro-optical module according to claim 7, wherein said first surface is substantially parallel to said mounting surface.
10. The electro-optical module according to claim 7, wherein said electro-optical component is embedded in a filling compound.
11. The electro-optical module according to claim 10, further comprising a bond wire partially embedded in said filling compound, said bond wire forming at least a portion of an electrical connection between said electro-optical component and said substrate.
12. An electro-optical module, comprising:
- a substrate formed with a mounting surface;
- a receptacle for an optical fiber plug defining a beam path substantially perpendicular to said mounting surface; and
- an integrated component unit mounted on said mounting surface, said integrated component unit comprising: a solid body defining at least first and second surfaces; an electro-optical component mounted on the first surface; and a focusing lens formed on the second surface, wherein the lens and the electro-optical component are directly aligned with one another in the beam path between said electro-optical component and said receptacle.
13. The electro-optical module according to claim 12, wherein the solid body further defines a depression on the first surface in which the electro-optical component is mounted.
14. The electro-optical module according to claim 12, wherein the receptacle includes a partition and wherein, upon insertion of the optical fiber plug, the partition is disposed between an end face of the optical fiber plug and the lens.
15. An electro-optical module, comprising:
- a substrate formed with a mounting surface;
- a receptacle for an optical fiber plug defining a beam path substantially perpendicular to said mounting surface; and
- an integrated component unit mounted on said mounting surface, said integrated component unit comprising: a lens component on which a lens is formed; an electro-optical component directly aligned with the lens in the beam path between said electro-optical component and said receptacle; and a first metallization extending over a portion of the lens component and connected in an electrically conducting fashion to the electro-optical component and to a first corresponding connector pad on the mounting surface of the substrate.
16. The electro-optical module according to claim 15, wherein the first metallization is electrically connected to an underside of the electro-optical component facing the lens.
17. The electro-optical module according to claim 15, wherein said integrated component unit further comprises a second metallization extending over a portion of the lens component and connected in an electrically conducting fashion to the electro-optical component and to a second corresponding connector pad on the mounting surface of the substrate.
18. The electro-optical module according to claim 17, wherein the second metallization is electrically connected to the electro-optical component via a bond wire.
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5617495 | April 1, 1997 | Funabashi et al. |
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0600645 | June 1994 | EP |
Type: Grant
Filed: Jan 22, 2001
Date of Patent: May 13, 2014
Assignee: Finisar Corporation (Sunnyvale, CA)
Inventors: Frank Meyer-Güldner (Berlin), Jörg-Reinhardt Kropp (Berlin), Mathias Grumm (Berlin), Georg Jeiter (Berlin)
Primary Examiner: Kevin S Wood
Application Number: 09/767,801
International Classification: G02B 6/12 (20060101);