Optical waveguides – Optical transmission cable – Ribbon cable
Reexamination Certificate
2000-11-28
2002-12-24
Sanghavi, Hemang (Department: 2874)
Optical waveguides
Optical transmission cable
Ribbon cable
C385S137000, C385S120000, C385S049000, C385S050000, C385S052000
Reexamination Certificate
active
06498882
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an apparatus and method to provide a connection for distinct optical channels between at least two optical or electro-optical devices using multiple optical fibers where the connection may have a pre-selected and different channel order at either end of the connection.
BACKGROUND OF THE INVENTION
In many optical and electro-optical systems (e.g., computer systems, programmable electronic systems, telecommunication switching systems, control systems, and so forth) it is highly desirable to achieve a reliable connection of multiple optical fibers between optical devices. However, achieving such a reliable connection is often difficult. Minimizing the number of optical fiber splices and connections provides advantages because these splices and connections greatly reduce the reliability of the connection between the devices. Hereafter, the term “optical device” is intended to include devices used in the optical and electro-optical systems mentioned above.
Connecting optical devices may require connecting multiple channels between the devices. Each optical device may have a series of distinct optical channels each of which must be connected to a corresponding channel on another optical device. The optical fibers connecting two optical devices are usually incorporated into groups of optical fibers. These groups may be in the form of a ribbon. When connected to an optical device, each optical fiber in a ribbon corresponds to a particular optical channel on the device. For example, referring to
FIG. 1
, if the group
11
of optical fibers
10
was a ribbon connected to an optical device then each optical fiber
10
within the group
11
will correspond to a particular optical channel e.g., C
1
-C
8
of the device. Also, it is inherent that the group
11
of optical fibers
10
has a respective optical channel order as illustrated by the order of C
1
-C
8
. As used throughout this application, the term “optical channel order” defines the order and location/sequence of each distinct optical channel which corresponds to a particular optical fiber in the group. In other words, the optical channel order functionally provides a map both for determining the optical channel that is connected to a fiber in a group, and for determining where that fiber is located with reference to the remaining fibers.
For example, referring to
FIG. 1
, group
11
is shown with an optical channel order where each optical fiber
10
corresponds to one of channels C
1
, C
2
, C
3
, C
4
, C
5
, C
6
, C
7
, and C
8
in the order and position shown. In comparison, as shown in
FIG. 2A
, group
1
has an optical channel order
5
where each optical fiber
10
corresponds to one of channels C
1
, C
2
, C
3
, and C
4
.
FIG. 2A
also illustrates group
2
as having an optical channel order
6
where each optical fiber
10
corresponds to one of channels C
5
, C
6
, C
7
, and C
8
.
It is to be understood that the number of optical channels discussed herein is not limited to the number illustrated in the drawings. The number of optical channels may range from 1 to the number required by any particular optical device. For example, a device may have
8
,
16
,
40
,
80
, or more optical channels. Moreover, optical channels C
1
-C
8
do not necessarily correspond to channels
1
-
8
of an optical device. Instead, the use of C
1
-C
8
are simply intended to serve as identifiers for reference purposes.
The development of optical devices with an increasing number of optical channels presents challenges in addition to the need for a reliable optical connection as described above. For instance, it is difficult to physically accommodate an increasing number optical fibers while simultaneously minimizing the space occupied by the optical device. One way of addressing this problem is to reconfigure an optical fiber ribbon to fit more optical fibers within a smaller area. However, reconfiguring the optical fibers in a ribbon will re-arrange the channel order of the ribbon from the proximal end to the distal end of the ribbon. The re-arranged channel order results in an undesirable channel order at the distal end of the ribbon. The problem is significant since suppliers usually sell the optical device with a ribbon already attached. Therefore, in order for a customer to properly connect the ribbon to a second optical device, it is necessary to re-arrange the channel order on distal end of the ribbon. For example, if a first optical device requires a channel order as shown by
FIG. 1 and a
second optical device requires a channel order as shown by
FIG. 2A
, but the re-configured ribbon attached to the first device has a channel order as illustrated
FIG. 2B
, then additional reordering of the optical fibers is required.
Three common solutions for overcoming these problem are described as follows:
(1) Customers can design their systems or devices with a particular channel order at the input/output of the device and use multi-fiber connectors or direct ribbon splices to prevent a mismatch of the channel orders. However, at the time of the filing of this application, there is no discernable industry standard for a channel order for multiple-fiber connectors. The lack of an industry standard may force the customer to change the configuration of their system to accommodate a specific channel order. However, not all customers are able to change the configuration of their system not all customers can change the configuration of their existing systems to accommodate the multiple-fiber connectors. Moreover, it may be difficult to retrofit older systems may to accommodate devices having differing channel orders.
(2) A connector assembly can be spliced onto the input/output fiber ribbon. The connector assembly separates the individual fibers and attaches a connector to each fiber. One drawback to this solution is that splicing a connector assembly onto a fiber ribbon introduces additional splices or connections into the system. These additional splices or connections result in higher insertion loss (signal loss) and, therefore, reduced system performance.
(3) The individual fibers on a reconfigured ribbon of optical fibers may be separated from the ribbon. A connector is then attached to each fiber. However, attaching multiple connectors directly onto individual output/input fibers causes an excessive scrap rate of devices, increases manufacturing time resulting in excessive product lead times, and eventual results in excessive costs for manufacturing the product.
Another solution to the problem discussed above is to re-sequence the ribbon extending away from the first optical device to produce a channel order that is required by the customer. This is accomplished by separating the individual fibers from the ribbon(s) extending away from the first optical device. The individualized fibers are often referred to as “singulated” fibers. Then, the individual fibers are re-sequenced to produce the customer-desired channel order. Next, the re-sequenced fibers are re-ribbonized at the customer-end. Therefore, the customer may splice the fibers to a separate connector assembly to connect the device to their system. Alternatively, the re-ribbonized fibers may be supplied with a connector. While the re-ribbonized fiber may be a desirable solution for some, it may not satisfy the needs of every customer. For example, given the limitations of re-ribbonizing numerous singulated fibers, the re-ribbonized portion may be of a different size than a ribbon that is typically used in the industry. The re-ribbonized fibers may also differ in other characteristics from a standard ribbon such as not being as robust, or not being as flexible. Accordingly, certain customers may require an optical device and ribbon where the channel order matches the customer's required channel order and the ribbon is not re-ribbonized. Moreover, customers may prefer to directly splice the ribbon from the optical device to their system and may not prefer to use a device with re-ribbonized fibers at the customer-end. Th
Buckelew Mark
Zhang Johnny
Amin & Turocy LLP
Knauss Scott
Lightwave Microsystems Corporation
Sanghavi Hemang
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