Optical waveguides – Miscellaneous
Reexamination Certificate
1999-03-25
2001-07-10
Font, Frank G. (Department: 2877)
Optical waveguides
Miscellaneous
C385S078000, C385S083000
Reexamination Certificate
active
06259856
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to optical fiber connectors, more particularly, to small form factor connectors for high density applications.
BACKGROUND OF THE INVENTION
Advances in lightwave technology have made optical fiber a very popular medium for large bandwidth applications. In particular, optical technology is being utilized more and more in broadband systems wherein communications between systems take place on high-speed optical channels. As this trend continues to gain more and more momentum, the need for efficient utilization of the precious real estate on circuit boards, racks/shelves, back planes, distribution cabinets, etc., is becoming ever increasingly important. In order to fulfill expectations across the industry, opto-electronic modules and optic fiber devices need to continue to become miniaturized, thereby taking full advantage of the maturity of micro- and opto-electronic technologies for generating, transporting, managing and delivering broadband services to the ever increasing bandwidth demands of end users at increasingly lower costs. Thus, the industry has placed an emphasis on small form factor optical connectors, such as the LC connector from Lucent Technologies, Inc. However, miniaturization is tempered by the requirements of transmission efficiency. For instance, with the advent of new standards such as gigabit Ethernet, wherein the transmission efficiency is becoming more and more critical, the performance of optical connectors is becoming correspondingly important for healthy operation of the system. Thus, it is desirable to obtain component miniaturization without sacrificing transmission efficiency, and preferably while improving transmission efficiency.
With the miniaturization of optical modules and optical fiber devices, the management of optical fiber congestion has become an issue at optical interfaces and connection distribution points. One solution is the use of multi-fiber ribbon in which a plurality of optical fibers are organized and molded side by side in a plastic ribbon. It is known to interconnect these ribbon cables by supporting the fibers between two support members made of a monocrystalline material, such as silicon. In the support members are V-grooves formed utilizing photolithographic masking and etching techniques. The fibers are placed side by side in individual V-grooves of one support member and the other mating support member having corresponding V-grooves is placed over the fibers so as to bind or hold the fibers in a high precision, spatial relationship between the mating V-grooves. The top and bottom support members sandwiching the multi-fiber ribbon are typically bonded together with a clamp or adhesive, forming a ferrule of a multi-fiber connector. Two mating ferrules with the same fiber spacing may then be placed in an abutting relationship so that the ends of the fibers of the respective ferrules are substantially co-axially aligned with one another, thereby forming a multi-fiber connection. If desired, such ferrules can be stacked in order to increase the interconnection density.
Multi-fiber ribbons and connectors have numerous applications in optic communication systems. For instance, some opto-electronic and optical application specific integrated circuits (OASIC) devices, e.g, optical switches, optical power splitters/combiners, routers, etc., have several input and/or output ports arranged as linear arrays to which a plurality of fibers are to be coupled. Further, since optical fibers are attached to launch optical signals into these devices and extract optical signals out of these devices, splicing of arrays of fibers (i.e., a multi-fiber ribbon) to such devices can be achieved using mutifiber connectors. Yet another possible application relates to an optical fan-out fabric where an array of fibers in a multi-fiber ribbon may be broken into simplex or duplex channels for distribution purposes, as is often desired.
A critical factor to the optical efficiency of a multi-fiber connector, whether or not stacked, is the precise alignment of the mating ferrules with regard to one another. As the ferrule structures utilized to achieve the precise axial alignment of corresponding optical fibers of a multi-fiber connection become smaller, there exist a need for connectors that are likewise space efficient so that full advantage of the miniaturized ferrule can be realized with higher interconnection density. Further, there also exist the need for multi-fiber connectors to be user friendly so that the operation and utility of the multi-fiber connector is intuitive to the workers that will be installing systems utilizing optical components. For example, it is desirable for multi-fiber connectors to have plug-and-play capability, in that they can be quickly and easily coupled to a piece of equipment, device, or one another.
In summary, there continues to exist a need for miniaturized multi-fiber connectors in order to take advantage of the more space efficient optical ferrules while, at the same time, increasing the functionality and ease of use of such multi-fiber connectors.
SUMMARY OF THE INVENTION
The present invention is a small form factor, multi-fiber connector having the footprint (cross-section dimension) of a LC connector for high density applications. A multi-fiber ferrule, which may or may not be stacked, is received in the front end of the housing. Optionally, a spring member is disposed within the housing for axially urging the multi-fiber ferrule outwardly. This assists in maintaining the end face of the ferrule flush with the device to which it is coupled. The housing includes an end cap which snaps into the housing body and holds the spring member. Thus, a multi-fiber stackable connector in accordance with the present invention is relatively simple in construction and assembly, inexpensive, and user friendly.
In accordance with an aspect of the present invention, a multi-fiber optical connector comprises a multi-fiber ferrule that terminates a plurality of optical fibers, and a housing having a first end, a second end, and an axial passageway extending from the first end to the second end, wherein the housing receives the multi-fiber ferrule in the first end thereof. The multi-fiber connector further comprises a spring member disposed in the passageway and interacting with the multi-fiber ferrule to axially urge the multi-fiber ferrule outwardly. The housing may include an end cap coupled to the second end thereof, and which interacts with and holds the spring member opposite the multi-fiber ferrule.
The multi-fiber ferrule may terminate a single linear array of optical fibers, or alternatively, stacked arrays of optical fibers. If the multi-fiber ferrule terminates stacked arrays of optical fibers, then the stacked arrays of optical fibers can be configured so that the lateral spacing between adjacent optical fibers is an integer multiple of the vertical spacing between corresponding optical fibers. The optical fiber spacing is preferably approximately 250 microns, or less.
The housing may define opposing slots, wherein the multi-fiber ferrule at least partially extends through the slots. In addition, the housing may comprise a spring latch extending from the housing.
The connector may further comprise an adapter having a first end that receives the housing and a second end that includes an aperture through which an end face of the multi-fiber ferrule protrudes. The adapter may be coupled to another adapter for facilitating the connection of two or more fibers, or the adapter may be coupled to an optical device such as a transceiver.
In accordance with another aspect of the present invention, a method for fabricating a multi-fiber optical connector comprises the steps of providing an elongated housing having a first end, a second end, and an axial passageway extending from the first end to the second end, placing a spring member in the axial passageway adjacent to the second end, and placing a multi-fiber ferrule in the first end of the plug housing so that the spring
Alston & Bird LLP
Font Frank G.
Lucent Technologies - Inc.
Stafira Michael P.
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