Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2002-05-28
2004-11-23
Lee, John D. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S092000
Reexamination Certificate
active
06821032
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to welding and sealing of electronic and/or optical packages, such as electro-optical modules utilized in transponders for use in optical telecommunication transmisions, and to weld joint and seal joint designs for such packages.
BACKGROUND OF THE INVENTION
Standard optical module packaging, such as in optical telecommunication applications, is used for an hermetic enclosure, after the alignment of the end of an optical fiber component with a related optical laser component. Such packaging is also used to house any associated lens and/or heat sink apparatus. Such optical telecommunication uses can include packaging of uncooled laser diodes, photo diodes, low power pump laser diodes, and lens integration with diodes. These standard packages primarily involve large so-called “butterfly” packages. Butterfly packages are essentially can-and-cover type arrangements that contain a separate optical module. That optical module may be built up separately, outside of the can, and then later installed into the can which is then covered off to create the hermetic seal. Alternatively, the optical module can be built up while inside of the can, but that is accomplished with great difficulty. Such modules, whether built up separately outside of the can and later installed, or while built up inside of the can, require a separate ceramic substrate, i.e., a base platform upon which all the optical-related components are mounted. Not only does the optical module include its own ceramic substrate, but then the can itself includes a separate base, on which the built up module is mounted. Thus, extra expensive components are required. Also, such butterfly type packages are quite tall (i.e., thick) because of their multilayer construction. This can result, in turn, in a relatively thick transponder unit.
Typically, because of the significant height of the side walls in such butterfly can constructions, the critical alignment of the metalized end of the optical fiber with the mating laser diode (whether a receiving or transmitting diode), is accomplished outside of the can. This is because, if such critical alignment is attempted inside the can, it is quite difficult to ensure that such alignment is accurately achieved, especially in the vertical direction which is hard to judge and measure inside the deep can's enclosure.
Such butterfly packages have long been the standard format for optical telecommunication transmission and pump laser diode modules. While satisfactory, for the most part, in operation, they are relatively too large, i.e., tall, significantly expensive, and require excessive components.
Separately, so-called ringframes are sometimes used to create optical packages. Ringframes are metal rings of a given profile that are brazed, i.e., soldered, onto metalized ceramic substrates. However, they have also proven deficient by preventing viewing from the side of the so-called “optical plane”, i.e., the horizontal plane relative to the ceramic substrate in which the incoming optical fiber end is aligned with the mating laser diode.
Hermetic sealing of such ringframe-type optical transmission modules is very important, where laser welding and seal joint soldering of such modules is used. However, because of the small dimensions inherent with such modules, there is a continuing problem with either improper seals and welds, or contamination of a prior solder joint by a later laser weld operation. Any of such problems can cause rejection of the almost-finished part for its intended end use in an optical telecommunication application. There have also been problems with side-viewing of the optical plane with such prior ringframe uses.
Further, there have been assembly problems present when having the so-called “fiber feedthrough” member, i.e., an extension channel or trough through which the optical fiber is inserted internally into the module and then later hermetically-sealed, mounted to the unit's cover. That is, it is difficult to properly slip the delicate optical fiber through the cover's feedthrough while simultaneously maneuvering the cover into position on the can of a butterfly package for the final hermetic cover seal. Also, having such a fiber feedthrough mounted to the cover, particularly low on the cover's side wall, present significant obstacles to proper laser seam welding.
Yet further problems with such butterfly packages and prior attempts at the use of ringframe constructions concerned solder joints, where large solder fillets are caused to occur on the outside of the can or ringframe during soldering operations. This can be a problem with both the associated laser weld (of the cover to the ringframe), and also cause undersirable extra “additive” width, i.e., which such a solder fillet presents to the overall width of the optical module.
REFERENCES:
patent: 3647534 (1972-03-01), Rice, Jr.
patent: 4647148 (1987-03-01), Katagiri
patent: 5058265 (1991-10-01), Goldfarb
patent: 5311402 (1994-05-01), Kobayashi et al.
patent: 5786548 (1998-07-01), Fanucchi et al.
patent: 6207950 (2001-03-01), Verdiell
patent: 6296336 (2001-10-01), Hattori
patent: 0381370 (1990-08-01), None
patent: WO 00/42464 (2000-07-01), None
International Search Report of the European Patent Office dated Sep. 8, 2003 (7 pages).
Selected pages of Kyocera online catalog, available at http://www.kyocera.co.jp/frame/product/semicon/oe_pkg/btf_pkg.html, concerning Kyocera multilayer ceramic butterfly type packages for optical telecommunication uses.
Askew Charles E.
Bennett Jeffrey A.
Epitaux Marc
Finot Marc A.
Kohler Robert M.
Marshall & Gerstein & Borun LLP
Song Sarah U.
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