Optical waveguides – With disengagable mechanical connector – Structure surrounding optical fiber-to-fiber connection
Reexamination Certificate
1999-04-01
2001-09-04
Chang, Audrey (Department: 2872)
Optical waveguides
With disengagable mechanical connector
Structure surrounding optical fiber-to-fiber connection
C385S055000, C385S056000, C385S070000
Reexamination Certificate
active
06283640
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to an optical fiber buildout assembly for use in coupling a first optical fiber cable to a second optical fiber cable. More particularly, the invention relates to an improved optical fiber buildout assembly in which the buildout cap is constructed and arranged to be received within the buildout base in one of a plurality of rotational positions about a longitudinal axis of the base for the selective optimization of an optical signal passed through at least a respective one of the first and second optical fiber cables.
BACKGROUND OF THE INVENTION
The use and construction of optical fiber cables, and optical fiber buildouts used for coupling optical fiber cables together is well known. Optical fiber cables are provided with optical fiber connectors at their ends, the optical fiber connectors being one of several known types of connectors, namely either an SC, an ST®, an FC, and/or an LC type of optical fiber connector. The SC, ST and FC connectors are provided with 2.5 mm diameter ferrules, whereas the LC type of optical fiber connectors are provided with a 1.25 mm diameter ferrule.
When it is desired to terminate an optical fiber cable, the cable is cut and stripped leaving an exposed portion of the optical fiber. The exposed optical fiber is passed within an elongate bore defined in, and extending along the longitudinal axis of a connector ferrule. The ferrule typically comprises either a rigid plastic or ceramic material, ceramic being preferred. The ferrule forms a part of the optical fiber connector of one of the types described above, such that it can be coupled to either a buildout base or cap, and the cap or base then coupled to one another for making the optical fiber coupling.
A problem that arises in making these optical fiber couplings, however, lies in the fact that the bore defined within the ferrule may have some eccentricity about the longitudinal axis of the ferrule, such that, although on a microscopic level, for example on the order of 9 microns, there may be some misalignment between the optical fibers housed within two respective ferrules as they are coupled to one another. This will result in an unintended or unexpected reduction in the value of the optical signal passed therethrough.
U.S. Pat. Nos. 4,738,507 and 4,738,508 to Palmquist, both of which are assigned to AT&T Technologies, Inc., the predecessor in interest to the assignee of this invention, each respectively disclose methods of identifying in which quadrant of the ferrule, about its longitudinal axis, the eccentricity of the optical fiber lies. This eccentricity, once identified is then keyed to a key or marker on the optical fiber connector or grip, such that when a connection is made between two similarly marked optical fiber connectors the amount of eccentricity between the ends of two adjacent coupled optical fibers is hopefully minimized for allowing the greatest possible value of the optical signal to be passed therethrough. Although the method, and optical fiber connectors of Palmquist have proven to be extremely useful in terms of identifying these eccentricities, and minimizing the impact of these eccentricities when making fiber optic connections in the field, they have the drawback of requiring that this be done in a controlled environment, for example in a production facility, and which method is not capable of being easily performed in the field for selectively optimizing, or attenuating signals, as desired.
An improvement to the concept of Palmquist is disclosed in U.S. Pat. No. 5,212,752 to Stephenson, et al., also assigned to AT&T Bell Laboratories, in which an optical fiber ferrule connector having enhanced provisions for tuning an SC type of connector is provided. The eccentricity of the ferrule passageway is tuned to the plug frame of the optical fiber connector, and more particularly to a key or mark on the plug frame, whereupon the plug frame is then assembled to the grip in alignment with the usual key thereon which identifies the quadrant in which the eccentricity is found.
What, however, this patent to Stephenson, et al. does not provide, is the ability to utilize these eccentricities to selectively tune the optical fiber connection in the field by either attenuating, or optimizing the value of the optical signal, as desired. The need exists, therefore, for an improved optical fiber buildout assembly which will quickly and easily overcome, and/or make advantageous use of these ferrule eccentricities, and which can be used with any one of the several different types of buildout bases and buildout caps.
SUMMARY OF THE INVENTION
The present invention provides an improved optical fiber buildout assembly which provides, for the first time, the ability to tune a signal passed through the optical fiber cables coupled within the buildout assembly as desired, for either attenuating or optimizing the optical signal passed therethrough. The improved buildout of this invention provides a simple, efficient, and highly flexible apparatus and method for quickly and easily coupling two optical fiber cables together so that the optical fiber connection can be tuned in the field, with the ability to advantageously use the eccentricity of the optical fiber within the ferrule of the terminated optical fiber cable end lies.
This invention provides this high degree of flexibility, as well as simplicity in design by providing a tunable optical fiber buildout for coupling a first optical fiber cable or connector to a second optical fiber cable or connector. The buildout has a buildout base formed about a longitudinal axis, the base having a first end and a spaced second end. A buildout cap is provided, the cap having a first end and a spaced second end as well. The buildout base is constructed and arranged to receive the cap at its first end in any one of a plurality of rotational positions about the longitudinal axis of the base such that the positioning of the cap within the base allows the user to selectively optimize the optical signal to be passed through at least one of the first and second optical fiber cable/connectors, respectively, in response to positioning the cap in one of the plurality of rotational positions about the axis of the base.
The buildout cap is constructed and arranged to be releasably fastened to the base, and has an alignment key formed thereon for providing a home rotational position with respect to the cap. The cap is constructed and arranged to be received within the base within one of four rotational positions spaced radially and 90° apart from one another about the longitudinal axis of the base, with respect to the alignment key.
The improved tunable optical fiber buildout of this invention also includes three separate buildout caps, a first cap for being received in the base in the first rotational position, a second cap for being selectively received in the base and either a second or third rotational position, and a third cap for being selectively received in the base in either the first or a fourth rotational position, as desired.
It is, therefore, an object of the present invention to provide a tunable optical fiber buildout.
It is another object of the present invention to provide an improved optical fiber buildout which is simple in design and construction, is rugged and durable in use, and which is easy to use in the field.
It is to these objects, as well as to the other objects, features, and advantages of the present invention, which will become apparent upon reading the specification, when taken in conjunction with the accompanying drawings, to which the invention is directed.
REFERENCES:
patent: 4738507 (1988-04-01), Palmquist
patent: 4738508 (1988-04-01), Palmquist
patent: 5082345 (1992-01-01), Cammons et al.
patent: 5212752 (1993-05-01), Stephenson et al.
patent: 5274729 (1993-12-01), King et al.
patent: 5687268 (1997-11-01), Stephenson et al.
patent: 5774612 (1998-06-01), Belenkiy et al.
patent: 5838855 (1998-11-01), Stephenson
patent: 5862282 (1999-01-01), Matsuura et al.
patent: 60
Sheldon Steven E.
Stephenson Daniel Lee
Alston & Bird LLP
Chang Audrey
Lucent Technologies - Inc.
Winstedt Jennifer
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