Optical waveguides – With disengagable mechanical connector – Optical fiber to a nonfiber optical device connector
Reexamination Certificate
2002-12-16
2004-12-07
Palmer, Phan T. H. (Department: 2874)
Optical waveguides
With disengagable mechanical connector
Optical fiber to a nonfiber optical device connector
C385S088000, C385S089000
Reexamination Certificate
active
06827505
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optoelectronic package structures, and more particularly to structures which efficiently locate optical fibers in desired positions therein.
2. Description of Related Art
An optoelectronic package has to perform many functions. Many planar optoelectronic devices must be precisely aligned to other optical or optoelectronic components including optical fibers. The package must provide mechanical support to maintain required alignment permanently or at least for a designed end of life period. The devices dissipate an amount of heat which must be removed efficiently. Optical fibers need to be routed in and out of the package. Electrical inter-connections need to be provided, and in most cases the package has to be sealed hermetically. Thus package design is a critical issue in successful performance of such devices. A good package design will provide the above functionality in an efficient manner, but it will also ensure successful processing hierarchy, so that the process steps are sequential.
U.S. Pat. No. 6,227,724 by Verdiell for “Method for Constructing an Optoelectronic Assembly” describes an OptoElectronic (OE) module a flexible element referred to as a “flexure” which is bonded to an optical fiber, and used to align the fiber-core to a lens and a laser beam from a light-emitting device such as a laser. Alignment is performed prior to the sealing of the OE module with a separate lid. Process and alignment tooling are described for fixing the fiber in the flexure. After alignment the fiber is permanently attached to the flexure by soldering, brazing or welding. The flexure is secured to the substrate by spot welding with a laser or using UV curable adhesives to a substrate frame and to the substrate base, thereby reducing flexibility of the optical fiber since the flexure is attached to the substrate. In summary, the flexure is used to align and retain the fiber in position prior to sealing the cap hermetically.
U.S. Pat. No. 6,220,765 and divisional application U.S. patent application Publication Ser. No. 2001/0001622 A1 of Tatoh for “Hermetically Sealed Optical-Semiconductor Container and Optical-Semiconductor Module” discloses the fabrication of a sandwiched base plate laminated onto the bottom of an optical package solely to prevent warping that produces distortion of the optical signal transmitted through the optical window in a hermetic package. Two plates, each made of a material with a specific Young's modulus are laminated together to produce a structure that will not warp during the package operation temperatures. While this may be relevant to Transmitting Optical Sub Assemblies (TOSAs) and Receiving Optical Sub Assemblies (ROSAs), it less relevant to the Wave Guide Package Structure (WGPS) of this invention where in one of the plates there is a very high conductivity material that allows spreading of local hot spots on a device.
U.S. Pat. No. 6,315,465 B1 of Mizue et al. for “Optical Module” discloses a Lead Frame Base structure which is selectively etched or stamped and subsequently used to laminate additional wiring layers to accommodate the packages circuitry. The selective interconnectivity between layers in achieved by using both conductive and non-conductive epoxies. The sole purpose of this type of circuitry is to minimize the use of wire bonding as an interconnection technique that allows for tighter/shallower encapsulation which together minimizes inductance and impedance issues, yielding better electrical performance. The LED is supported and mounted externally of the encapsulated body by bending the two support leads. This has distortion issues when the temperature rises during operation. In any event, while Mizue et al. may have particular relevance in Optical Transmitter/Receiver packages it is of less relevance to the wave guide of this invention.
U.S. Pat. No. 6,270,263 B1 of Iwase et al. for “Optical Module” describes and optical module with a silicon (Si) substrate mounted with optical devices (laser and photo diodes) and with wiring pattern on it. The substrate assembly is assembled with two synthetic resin pieces (top and bottom) sealed with an adhesive. The synthetic resin package has features such as various holes and ferules in configurations which allow for optical fiber(s) to be introduced into an assembled package and to be sealed next to the laser diode by an adhesive. A synthetic resin package material which is sealed with an adhesive is consider to be non-hermetic.
U.S. Pat. No. 5,355,429 of Lee et al. for “Optical Fiber Strain Relief Apparatus” discloses apparatus for reducing optical fiber strain in a limonite structure with strain relief hardware. The hardware can consist of anchor with crimp ring and connector adapter in various configurations. In an embodiment in which the fiber is bent at an angle the emphasis is upon protection of the optical fiber from external forces which are absorbed by the anchor and protective cabling, but there is no suggestion of providing slack in the optical fiber to accommodate strain due to Coefficient of Thermal Expansion (CTE) mismatch. Moreover, there is no discussion of strain relief in optoelectronic modules or packages.
U.S. Pat. No. 6,075,914 of Yeandle for “Apparatus for Connecting an Optical Fiber to an Optical Device” discloses a method of attaching a optical fiber in a ‘V’ groove on a device without securing the fiber with an adhesive or solder. The securing of the fiber is on a inclined pad with adhesive away from the device which allows elastic deformation and urges the fiber into the ‘V’ groove, but there is no discussion of packaging thereof.
U.S. patent application Publication Ser. No. 2001/0017964 A1 of Setoguchi for “Optical Interconnection Module” describes a base formed of a high CTE material (as well as alumina). The base includes internal metallurgy, grooves for fiber alignment, multiple fiber alignment, matched index adhesives between the fiber and the laser, but there is no mention of any method for proving strain relief for the fibers nor is their any statement or concern about CTE strain in the fiber induced by the substrate during thermal excursions.
U.S. Pat. No. 6,273,620 B1 of Kato et al. for “Semiconductor Light Emitting Module” is specifically related to a fiber grating laser module where the grating is formed within the fiber and hence the oscillation length can be adjusted independent of the Semiconductor Optical Amplifier (SOA). The drawings for the module incorporated in the patent do not show features related to an optical fiber strain relief structure.
U.S. Pat. No. 6,205,264 B1 by Jin et al “Optical Assembly with Improved Dimensional Stability” describes a process of incorporation of fine dispersoid particles in various solder compositions and a resulting structure provided for improvement in the creep properties of the solders thus giving a more dimensionally stable optical assembly created using these ‘improved’ solders. There is no mention of a strain relief for optical fibers.
SUMMARY OF THE INVENTION
An object of this invention is to provide strain-relief in optical fibers connected to an optoelectronic package.
In accordance with this invention, an S-bend is provided in an optical fiber for strain-relief. The strain-relief S-bend is incorporated in the fiber to reduce stress on the optical fiber during thermal excursion of the package during operation of the devices contained therein and under various environmental conditions.
Further in accordance with this invention, the package includes retractable structures secured to the lid of the package. When the lid is placed in position to close the package the retractable elements are aligned with an existing fixed fiber-array which has sufficient slack to be deflected to form an S-bend without damage. The retractable structures push the optical fibers down into the package to produce strain relief S-bends in the optical fibers during the sealing of the lid of the package. The retractable structures are secured to the lid of th
Herron L. Wynn
Interrante Mario J.
Lin How T.
Ostrander Steven P.
Ray Sudipta K.
Jones Graham S.
Palmer Phan T. H.
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