Optical waveguides – Optical transmission cable – Ribbon cable
Reexamination Certificate
2000-02-04
2001-11-27
Ullah, Akm E. (Department: 2874)
Optical waveguides
Optical transmission cable
Ribbon cable
Reexamination Certificate
active
06324325
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to optical fiber interconnect devices of the type known as a “perfect shuffle” and to processes for preparing such interconnect devices. More particularly, the present invention relates to devices smaller in size than prior art devices and to devices that exhibit superior optical properties including lower attenuation loss (lower insertion loss) and to fabrication processes which produce such devices.
BACKGROUND OF THE INVENTION
In applications for the transmission of information via laser light energy through optical fibers, the optical fibers are typically arranged into groups and these groups are assembled as ribbons that contain multiple optical fibers. The groups may be arranged into supergroups by stacking multiple optical fiber ribbons to form an array structure. Such an array is typically comprised of rows and columns of fibers, each row comprising all the fibers contained within a particular ribbon and each column comprising one particular fiber from each ribbon. When it is necessary to distribute information from one optical fiber in a row group to an optical fiber in a column group an interconnect device known in the art as a “perfect shuffle” is typically used. Since interconnection devices typically introduce loss when inserted into a fiber optic transmission system, it is desirable that losses within the device be as low as possible. Single mode optical fiber systems are desirable when large amounts of information need to be transmitted but are particularly sensitive to transmission losses related to precise alignment of fibers. Prior art devices typically create a physical connection within the device, such as a splice or other optical junction, between an incoming fiber and an outgoing fiber and this physical connection creates an optical loss within the interconnection device.
Thus a need exists for an optical fiber perfect shuffle interconnection device that can be easily manufactured and which achieves lower optical losses than prior art devices.
The present invention overcomes many of the limitations of the prior art and provides some additional benefits at reduced cost of manufacture.
SUMMARY OF THE INVENTION
There is disclosed and claimed herein an optical fiber interconnect apparatus of the type known as a “perfect shuffle” and methods of making this optical fiber interconnect apparatus, useful for connecting two M by N arrays of optical fibers, each array comprising M rows and N columns or N rows and M columns of fibers, wherein each row is identified by a first subscript i and each column is identified by a second subscript j, wherein a fiber at a input position ij of the input array is routed to a corresponding fiber at an output position ji of the output array, the method comprising: (a) assembling a first input array of optical fibers, comprising M optical fiber ribbons, where each ribbon comprises a row-group of fibers and (b) assembling a second output array of optical fibers, comprising N optical fiber ribbons, where each ribbon comprises a column-group of fibers so that a fiber at a position ij of the input array is routed to a corresponding fiber at a position ji of the output array.
The first input array of optical fibers is assembled by assembling a first group of ribbons each comprising a row-group of fibers. In a first ribbon assembly method, each ribbon is assembled by laying down a plurality of N optical fibers onto a first adhesive-coated carrier tape. The tape has a predetermined width, a first and second end and a centerline. Each fiber has a first end corresponding to the input array and a second end corresponding to the output array. A first portion of each fiber is placed on the adhesive-coated surface of the tape parallel to the centerline. The first fiber portion is chosen to be adjacent the first end of each fiber, with the first end of each fiber extending substantially beyond the first end of the carrier tape and the second end of each fiber extending substantially beyond the second end of the carrier tape. After the fibers are laid down on the first tape a second adhesive-coated carrier tape is positioned atop the first tape with the adhesive coated surface facing the adhesive coated surface of the first tape so that the first fiber portions are sandwiched between the first and second tapes to form the first optical fiber ribbon. The ribbon assembling step is then repeated until M ribbons are assembled. The M ribbons are stacked atop one another to form the first input array of fibers.
The second output array of optical fibers is created by assembling a second group of ribbons, each comprising a column-group of fibers. A first ribbon of the second group is assembled by selecting a first optical fiber from each row-group (i.e., each ribbon) of the first array. A second portion of each selected fiber is laid down onto a third adhesive-coated carrier tape. This second fiber portion is chosen to be adjacent the second end of each fiber, with the second end of each fiber extending substantially beyond the second end of the carrier tape.
The third adhesive-coated carrier tape has first and second ends and a centerline. The first end of the third tape is adjacent to the second end of the first and second tapes. Each fiber is placed on the adhesive-coated surface of the tape parallel to the centerline with the second end of each fiber extending substantially beyond the second end of the third carrier tape. A fourth adhesive-coated carrier tape is then positioned atop the third tape so that the selected fibers are sandwiched between the third and fourth tapes to form a first column-group optical fiber ribbon.
A second ribbon of the second group is assembled by selecting a second optical fiber from each row-group (i.e., each ribbon) of the first array and sandwiching these second optical fibers between third and fourth tapes to form a second column-group optical fiber ribbon. Successive ribbons of the second group are assembled by selecting successive optical fibers from each row-group (i.e., each ribbon) of the first array until N ribbons are assembled. The N ribbons are then stacked atop one another to form the second output array of fibers.
In a second assembly method the ribbons are formed by positioning the fibers in a side-by-side arrangement and coating them with a liquid adhesive that is then cured to form the ribbons.
Thus a fiber at input position ij of the input array is routed to a corresponding output position ji of the output array, without any splices or optical junctions within the device.
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patent: 5312545 (1994-05-01), Kuo et al.
patent: 5830306 (1998-11-01), Hinson
patent: 6007413 (1999-12-01), Fitz
patent: 6093275 (2000-07-01), Hinson
patent: 6171177 (2001-01-01), Fitz
patent: 6181856 (2001-01-01), Brun
Booth Bruce L.
Furmanak Robert J.
Ryan Danahey
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