Method of producing core protrusion relative to cladding in an optical fiber of a fiber optic connector

#The present invention relates generally to a method for producing core protrusion relative to the cladding in an optical fiber mounted in a ferrule of a fiber optic connector. The present invention also relates generally to a fiber optic connector which includes an optical fiber having such core protrusion.

#Optical fibers are widely used in a variety of data transmission applications including, primarily at the present, the telecommunications industry. Because optical fibers transmit voice and other data far more rapidly and efficiently than copper wire, the demand for optical fibers is continuing to increase. For example, optical fibers no longer serve merely as the medium for long distance signal transmission but are increasingly routed directly to the home or, in some instances, directly to a desk or other work location to network computers. These fiber optic networks incorporate a number of remateable connectors instead of permanent splices in order to provide flexibility in revising or upgrading the networks. The remateable connectors generally include an optical fiber which is held in a 2.5 mm zirconia or stainless steel ferrule by an adhesive.

#Because these remateable connectors are a source of reflectance, efforts have been focused on improving the relative geometry between the optical fibers and the ferrule in the connectors in order to improve connector reflectance. Due to the small size of the optical fibers, maintaining exact tolerances, generally measured in terms of microns (.mu.m) or nanometers (nm), is very critical but extremely difficult to do.

#FIG. 1 is a perspective view illustrating the step according to one embodiment of the present invention of polishing the end of the optical fiber mounted in a fiber optic connector.

#FIG. 2A is a cross-sectional side view illustrating the step of applying the etching solution to the end of the optical fiber mounted in a fiber optic connector.

#FIG. 2B is a cross-sectional side view illustrating the step of etching the end of the optical fiber to produce core protrusion relative to the cladding.

#The present invention will now be described more fully hereinbelow with reference to the accompanying drawings, in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein; rather, this embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

#Referring now to FIG. 5, the sequence of steps according to a preferred embodiment of the present invention is illustrated. First, a laser is used to remove excess fiber and adhesive from an end of a connector ferrule. Next, the end of the ferrule is rough polished in order to form a convex surface. The optical fiber in the ferrule is then etched with a solution which preferentially removes the cladding. The resulting protruding core is then fine polished to remove any recess or undercut in the core resulting from the etching process. Finally, the protruding core is irradiated with a laser to provide a smooth surface for contact with a second optical fiber which may be mounted in another ferrule. Alternatively, the protruding core resulting from the etching step may be irradiated with a laser followed by fine polishing or may simply be irradiated with a laser.

#The improved fiber optic connector as shown in FIG. 6 results from the protrusion of the core of the fiber beyond the cladding. As a result of the etching process, the optical fiber may be recessed below the end of the ferrule. The present invention, however, is directed to the protrusion of the core relative to the cladding and not to the position of the end of the optical fiber relative to the end of the ferrule. Due to the small size of the fiber relative to the ferrule, the drawings do not reflect the true relative sizes of the core, cladding, and ferrule.