|Publication number||USH2144 H1|
|Application number||US 10/341,829|
|Publication date||Feb 7, 2006|
|Filing date||Jan 14, 2003|
|Priority date||Jan 14, 2003|
|Also published as||US20040136638|
|Publication number||10341829, 341829, US H2144 H1, US H2144H1, US-H1-H2144, USH2144 H1, USH2144H1|
|Inventors||David Robert Baechtle, Dwight David Zitsch, Brian Patterson|
|Original Assignee||Tyco Electronics Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (12), Non-Patent Citations (9), Referenced by (1), Classifications (8), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates generally to optical circuits, and particularly to a multi-layered optical circuit.
Advances in optical networks, systems and connectors have resulted in a need to manage an increasing number of optical fibers in limited space. Numerous optical fibers are often managed by creating an optical circuit. An optical circuit includes a substrate to which optical fibers are arranged in a desired circuit pattern and permanently fixed to accomplish a desired fiber management, shuffling, cross-connection or distribution scheme. A typical optical circuit 10 (see
Lengths of the fibers extending beyond the edge of the substrate form termination legs 22 that are terminated with the desired connectors 24 (see FIG. 1A), such as LIGHTRAY MPX® brand connectors. MTP®, MT-RJ or other MT-type connectors, LC-, FC-, or SC-type connectors, etc. Optically, the termination legs may be ribbonized for subsequent routing and/or convenient terminating to multi-fiber connectors. Exemplary optical circuits are shown in
Applicant has observed that such optical circuits, though often flexible out of plane and/or having a thickness, are “planar” in that they involve either: (a) laminating portions of fibers between adjacent fiber end connectors to a single substrate; or (b) routing fibers between adjacent connectors in a single plane, on one side of a single substrate.
Such planar optical circuits are limited in the number of fibers that can be routed upon a given area of substrate. Such limitations are primarily due to a minimum bend radius characteristic of the fibers, and a maximum number of fibers that can be physically routed in stacked arrangement before causing microbends and microbend loss.
The present invention provides a multi-substrate optical circuit and a layered optical circuit fabricated from the multi-substrate optical circuit. The multi-substrate optical circuit is similar to a conventional planar optical circuit in that it includes optical fibers affixed to a substrate to provide a desired circuit pattern, and in that portions of the optical fibers extend beyond the substrate(s) to form termination legs for termination to desired connectors. Hence, conventional optical circuit fabrication materials, techniques and equipment may be used to fabricate the multi-substrate optical circuit. The multi-substrate optical circuit differs from a conventional planar optical circuit, however, in that the optical fibers are routed between and bonded to multiple distinct substrates. The substrates thereby become interconnected by a free, unaffixed length of the optical fibers that permits bending of the fibers to stack the individual substrates in an overlapping manner to form a layered optical circuit in accordance with the present invention. The length should be sufficient to permit such bending without violating a minimum bend radius of the fibers. Accordingly, a continuous communications path is provided across multiple substrates, and across multiple layers of overlapping substrates.
In this manner, the layered optical circuit achieves a smaller form factor for an overall optical circuit by overlapping, e.g. stacking, planar optical subcircuits fabricated in a manner similar to that well known in the art. Accordingly, a relatively large layered optical circuit may occupy a relatively small footprint of a backplane, carrier, etc. The layered optical circuit provides a greater area of substrate for routing of fibers in a given footprint, and, therefore, a greater number of fibers, and/or a more complex circuit pattern, may be routed over that footprint while avoiding bend radius and microbend problems.
A method for fabricating a multi-substrate optical circuit and a layered optical circuit is also provided.
Conceptually, the present invention provides an optical circuit that is layered to achieve a smaller form factor for an optical circuit by overlapping, e.g. stacking, multiple interconnected planar optical circuits. A layered optical circuit provides a greater area of substrate for routing of fibers in a given footprint (e.g. surface area on a backplane or carrier), and, therefore, a greater number of fibers, and/or a more complex circuit pattern, may be routed over that footprint while avoiding bend radius and microbend problems. The optical circuit may be constructed from a multi-substrate optical circuit including separate substrate supported optical subcircuits connected by free fibers having a length sufficient to permit overlapping of the substrates while maintaining at least a minimum bend radius for the fibers.
More specifically, the first substrate 42 supports a first portion 54 of each the optical fibers, e.g. by supporting the fibers on a pressure sensitive adhesive coating of the substrate 42 and/or fixing them with a protective layer, as generally known for planar optical circuits, to form a first optical subcircuit 60. The second substrate 44 supports a second portion 56 of each of the optical fibers, e.g. by arranging the fibers on a pressure sensitive adhesive coating of the substrate 42 and/or fixing them with a protective layer as generally known for planar optical circuits, to form a second optical subcircuit 70. Each of the first optical subcircuit 60 and second optical subcircuit 70 is therefore similar to a planar optical circuit of the prior art. However, the subcircuits 60, 70 are interconnected by free fibers to form a continuous communication path across these, and potentially other, substrates. As used herein, the term “free fiber” refers to fibers that are not affixed to a substrate, regardless of whether such fibers are ribbonized.
It will be appreciated by those skilled in the art that optical fibers, particularly when ribbonized, have limited flexibility for bending while maintaining desirable signal transmission capabilities. This is partly due to the structure of flat, multi-fiber ribbons which readily permit bending primarily out-of-plane, but prevents substantial bending in-plane. This limited flexibility is accounted for in constructing a multi-substrate optical circuit for fabrication into a layered optical circuit, by providing a sufficiently long length of free fibers between the first and second substrates to permit the desired bending, e.g. bending for overlapping the first and second substrates/optical subcircuits without violating a minimum bend radius parameter, typically approximately one (1) inch, of each of the optical fibers within the region of the free fibers. For example, a length of approximately six (6) inches to approximately seven (7) inches has been found sufficient for bare fibers, and a length of approximately seven (7) inches to eight (8) inches has been found sufficient for ribbonized fibers. Accordingly, the length of free fibers may be bent, twisted or otherwise routed as the substrates are repositioned into a different arrangement, such as a compact overlapping layered arrangement.
In this manner, layers of the layered optical circuit are interconnected, and may communicate, via continuous communications paths, e.g. via continuous lengths of optical fiber or separate lengths of connectorized optical fibers connected by a suitable connector. This latter arrangement may be particularly useful to construct relatively large layered optical circuit having many multi-substrate optical circuits and/or optical subcircuits. Rather than routing and fixing fibers in essentially two dimensions as in a typical planar optical circuit, fibers may thereby be routed over three dimensions as multiple interconnected planar optical circuits are stacked over a given footprint area, thereby providing greater substrate area for routing of fibers per unit of footprint area.
With specific reference of the embodiment of
A layered optical circuit 100 (see
In this particular example, each of the optical fibers has a first end extending beyond an edge 42 a of the first substrate 42, and a second end extending beyond an edge of the second substrate 44. These ends form the termination legs 55 that are positioned adjacent one another and may therefore be easily re-ribbonized and/or terminated to a connector 64, as desired. The co-location and alignment of multiple fibers/termination legs from multiple layers of the layered optical circuit is particularly well-suited to termination to a multi-row ferrule, such as recently developed multi-row MPX connectors. Additionally, such multi-substrate optical circuits permit interconnection of fibers within a row, or between rows, of a single multi-row ferrule.
It should be appreciated that numerous layers may be stacked, using any desired combination of techniques such as planar rotation, inversion and translation, to form a layered optical circuit in accordance with the present invention. The individual planar subcircuits may be formed as discussed above, in a suitable circuit pattern to achieve the desired connectivity, fiber routing, etc. and layered optical circuit. By way of further example,
It should be noted that a multi-substrate optical circuit and a layered optical circuit in accordance with the present invention may have numerous configurations, as desired. For example,
In any of the foregoing embodiments, after the substrates are positioned in at least partially overlapping relationship, they will tend to move or separate to allow the fibers to relax from their bent state. To maintain the substrates in the desired relative positions, the substrates may be affixed in fixed relative positions in any suitable manner, e.g. by adhesively or otherwise bonding the substrates to one another, mechanically fastening the substrates to one another by pins, screws, etc., or by mounting both substrates to a common carrier, such as a backplane, cabinet, etc.
A multi-substrate optical circuit may be fabricated by providing a first substrate and a second substrate in substantially the same plane as the first substrate. The second substrate is preferably positioned at a distance from the first substrate to provide a desired length between adjacent edges of the first and second substrates, as discussed further below. Alternatively, the substrates are closely positioned and a loop of desired length is left between edges of the adjacent substrates. Substrates of a type typically used for optical circuits are suitable, e.g. a flexible substrate provided with a pressure sensitive adhesive layer. For example, these substrates may be provided on a substantially planar bed of a CNC fiber routing machine typically used to fabricate optical circuits, and the fibers may be laid/routed in the usual manner, except that the fibers are routed, in part, over an area that is not provided with a substrate, and that is positioned between substrates to which the fibers are to be affixed (the free fiber area).
The fabrication includes mounting to the first substrate a first portion of each of a plurality of optical fibers. This may be performed in a traditional manner by pressing the fibers onto the pressure sensitive adhesive of a substrate, and/or providing a protective top coating as is well known in the art. This effectively forms an optical circuit of the prior art.
In accordance with the present invention, the method also involves mounting to the second substrate a second portion of each of the plurality of optical fibers. The second portion is a portion longitudinally spaced from the first portion by a third portion of each of the plurality of optical fibers. In other words, a portion of the same fibers affixed to the first substrate are then affixed to the second substrate in a similar manner, e.g. by pressing the fibers on the pressure sensitive adhesive of the second substrate and/or providing a protective layer. The second portion is thereby affixed to the second substrate to leave a third portion that has a length for permitting overlapping of the first and second substrates without exceeding a minimum bend radius of each of the optical fibers within the third portion. The length required is in part a function of the flexibility of the optical fibers (with cladding, jacketing, etc.), whether the fibers are ribbonized, and the number of fibers in the ribbon, etc. Determining a length for permitting desired bending of fibers without exceeding a minimum bend radius is well known in the art.
A layered optical circuit may then be fabricated from the multi-substrate optical circuit by positioning at least a portion of the second substrate to overlap the first substrate. The causes the portion to be displaced from the plane of the first substrate and the substrates to overlie one another to create a space savings. As discussed above, the positioning of the substrates in a layered orientation may include a planar rotation, a planar translation or an inversion of at least one of the substrates. Preferably, the layered substrates are then affixed in fixed relative positions.
Optionally, mounting of fibers to the second substrate may involve twisting the plurality of optical fibers in a transition area (third portion) defined between the first and second portions of the optical fibers, such that the inversion of the substrate(s) tends to untwist the optical fibers. Alternatively, a twist may be built into the fibers of the multi-substrate optical circuit, as discussed above, such that the inversion tends to untwist the fibers.
The layered optical circuit may then be used substantially similarly to a planar optical circuit of the prior art, e.g. by terminating the termination legs to desired connectors, mounting the layered optical circuit on a carrier, backplane, cabinet, etc. and/or connecting the layered optical circuit to other circuits, signal transmission hardware, etc.
Having thus described particular embodiments of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications and improvements as are made obvious by this disclosure are intended to be part of this description though not expressly stated herein, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only, and not limiting. The invention is limited only as defined in the following claims and equivalents thereto.
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|Citing Patent||Filing date||Publication date||Applicant||Title|
|US9146374||Sep 26, 2013||Sep 29, 2015||Adc Telecommunications, Inc.||Rapid deployment packaging for optical fiber|
|International Classification||G02B6/08, G02B6/12, G02B6/43|
|Cooperative Classification||G02B6/43, G02B6/08|
|European Classification||G02B6/08, G02B6/43|
|Jan 14, 2003||AS||Assignment|
Owner name: TYCO ELECTRONICS CORPORATION, PENNSYLVANIA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BAECHTLE, DAVID ROBERT;ZITSCH, DWIGHT;PATTERSON, BRIAN;REEL/FRAME:013665/0350;SIGNING DATES FROM 20021212 TO 20030104