Optical waveguides – With optical coupler – Plural
Reexamination Certificate
2002-04-24
2004-01-13
Patel, Tulsidas (Department: 2839)
Optical waveguides
With optical coupler
Plural
C385S061000
Reexamination Certificate
active
06678442
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fiber optic networks, and more particularly to fiber optic connectors and functional blocks that enable fiber optic to the home while achieving a reliable and cost effective network.
DESCRIPTION OF RELATED ART
Fiber To The Home (FTTH) is an attractive option that has received a significant amount of attention in recent years. Significant technological advances have been made in fiber optic communications. FTTH promises to deliver “true” broadband access compared to existing access technologies including network connections based on phone lines (DSL) or coaxial cable. The hybrid-fiber-coax (HFC) architecture is a relatively recent development adopted by the cable industry in which optical signals are transported from a source of distribution (e.g., a headend) to multiple electro-optical conversion nodes via fiber optic cables. Each conversion node converts between optical signals and electrical signals using simple photo-detector technology, where the electrical signals are carried via coaxial cables routed from the conversion nodes to individual subscriber locations. Current HFC designs call for fiber nodes serving about 500 homes on the average, although the nodes could be further segmented to smaller coaxial-serving areas.
A “last mile” solution to achieve FTTH would appear to be to replace the coax cables of an HFC architecture with fiber optic cables. The traditional approach to FTTH is to route a separate optical fiber to each subscriber location. Such a solution, however, results in about 1,000 fibers on the average between each local node and the neighborhoods served (2 per house for full duplex). The average number of fibers behind each person's home in such a configuration is about 200. This has proved to be an unwieldy architecture that is difficult to establish and prohibitively expensive to maintain. FTTH has not yet proved to be cost effective to deploy and/or operate.
Experience from the coaxial cable configurations has demonstrated that cable problems can and do occur. Generally, damage to one or more cables reduces or otherwise eliminates service in corresponding downstream geographic areas. Coaxial cables are relatively inexpensive and easy to replace and/or repair. Fiber optic cables, on the other hand, are relatively expensive and difficult to repair. In proposed configurations, each cable has a multitude of optical fibers. During the installation process, the individual fibers must be identified and isolated to route each fiber to the appropriate location. Fiber optic cable repair has typically required very specialized equipment involving a sophisticated splicing operation that must be done in a relatively clean environment. The solution has been a truck loaded with very expensive fiber optic splicing equipment, referred to as a “splicing van”. The general process is to clean, align and splice, which involves melting and firing the individual fibers. Although less of a problem for major thoroughfares, such as highways or rural access routes where van access is readily available, the splicing van must still be deployed to the trouble spot in the network. Even when access to the trouble spot is available, the splicing process can consume a considerable amount of time, sometimes several days. This is especially true in the last mile, where the cable is often routed in locations that are not van-accessible (such as someone's back yard).
It is desired to solve the last mile dilemma so that FTTH become a viable and economic reality.
SUMMARY OF THE PRESENT INVENTION
A fiber optic connector according to an embodiment of the present invention includes a body forming a fiber insertion path and an optical lens. The fiber insertion path is configured to receive an optical fiber and extends within the body to an internal end. The lens includes a first concave surface formed at the internal end of the fiber channel and a second concave surface formed on an external side of the body. The lens defines a centerline extending between the center points of the first and second concave surfaces. The first concave surface of the lens is operative to spread light sourced from an optical fiber inserted into the fiber channel towards the second concave surface and to re-direct light converging from the second concave surface towards the first concave surface onto the optical fiber. The second concave surface has a suitable size for visual inspection and cleaning. The second concave surface is configured to re-direct light diverging from the first concave surface to a direction generally parallel with the centerline and to re-direct light directed towards the second concave surface and in parallel with the centerline towards the first concave surface. The body may be configured to form a multiple optical fiber connector in which the body forms multiple individual fiber insertion paths and corresponding optical lenses.
The body may be made of a material that is optically transparent in an applicable wavelength range suitable for optical communications. The fiber insertion path may include a fiber guide chamber located between a fiber insert opening on an external side of the body and an opening of the fiber channel opposite the internal end. The fiber insert opening has a visible size suitable to facilitate threading an optical fiber. The fiber guide chamber is configured to guide an inserted optical fiber into the fiber channel. The fiber guide chamber is formed within the body and may have tapered walls between the fiber insert opening and the fiber guide channel opening. The fiber insert opening may have a size that is sufficient to encompass a fiber cable sheath inserted within.
The fiber optic connector may include a fiber tip cleaner located within the fiber insertion path that cleans a tip of an optical fiber while the optical fiber is inserted. The fiber tip cleaner may include, for example, at least one sheet of a low residue paper. The fiber optic connector may include a fiber bonding system located along the fiber insertion path that is operative to hold the optical fiber to the body after insertion. In a specific configuration, the fiber bonding system includes first and second epoxy chambers, first and second epoxy barriers, and first and second epoxy hammers. The epoxy chambers are provided within the body adjacent the fiber insertion path and filled with epoxy resin and hardener polymers, respectively. The epoxy barriers are positioned between the epoxy chambers and the fiber guide chamber operative to temporarily contain the epoxy polymers within the epoxy chambers. The epoxy hammers are provided in the body between outer opposing surfaces of the body and the epoxy chambers. The epoxy hammers are configured to force the epoxy polymers to breach the epoxy barriers to release the epoxy polymers into the fiber insertion path in response to compression applied to the first and second epoxy hammers.
In an alternative embodiment, an epoxy filter insert is provided that incorporates the fiber tip cleaner and the fiber bonding system. The epoxy filter insert may be configured to mount within the fiber insertion path. The epoxy filter insert may include, for example, a casing, a pair of epoxy chambers and at least one sheet of a low residue paper. The casing has an outer surface between a front end and a back end which is configured to mount to the inner walls of the body with the back end towards an opening of the fiber insertion path. The epoxy chambers are provided within and at the front end of the casing. The epoxy chambers are separated by suitable membranes and filled with epoxy polymers. The low residue paper sheet(s) are provided within and at the backend of the casing. The epoxy filter insert is positioned to block the fiber insertion path when mounted therein so that when an optical fiber is inserted, the tip of the optical fiber breaches the epoxy chambers allowing mixture of the epoxy polymers within fiber insertion path. The tip is also cleaned while breaching the low residue paper sheets while t
Gall Donald T.
Pangrac David M.
Pangrac and Associates Development, Inc.
Patel Tulsidas
Stanford Gary R.
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