FIELD OF THE INVENTION

The present disclosure relates to terminating the ends of fiber optic cables with ferrules.

BACKGROUND OF THE INVENTION

Typically the end of a fiber optic cable is terminated by a fiber optic connector by gluing the fiber within the cable to a ferrule of the connector. A well known fiber optic cable size includes an inner glass fiber of 125 microns in diameter, with an outer coating of 250 microns in diameter, covered by a polymeric buffer layer of 900 microns in diameter.

One problem with terminating fiber optic cables can include fiber breakage at the rear interface area between the end of the glass fiber and the ferrule. In this interface area is the epoxy used to hold the fiber to the ferrule. Such breakage tends to increase in response to greater temperature fluctuations during use of the cables. Differences in thermal expansion are believed to cause the breakage. There is a need to improve the interface between fiber optic cables and connectors to reduce fiber breakage, especially due to thermal stress.

SUMMARY OF THE INVENTION

A fiber optic ferrule includes a body extending from a first end to a second opposite end, with the body including a smooth and continuous axial passage extending between the first and second ends. The smooth and continuous axial passage includes a first diameter portion having a diameter of at least 125 microns and a second diameter portion having a diameter of at least 250 microns. The second diameter portion is positioned between the first diameter and the second end. The smooth and continuous axial passage further defines a funnel shape at the second end extending inward from the second end to the second diameter portion. The smooth and continuous axial passage further defines a first transition between the first and the second diameter portions and a second transition between the second diameter portion and the funnel shape.

A method of assembling a terminated fiber optic cable includes providing a cable with an inner fiber at 125 microns, an outer coating at 250 microns, and a buffer layer at 900 microns. The method includes stripping a portion of the coating from an end of the cable to expose a portion of the inner fiber, and stripping a portion of the buffer layer to expose a portion of the coating. The method further includes inserting the exposed fiber and the exposed coating into a smooth and continuous axial passage of a ferrule having first and second inner diameters, wherein the first diameter is at least 125 microns, and the second diameter is at least 250 microns, and adhesively holding the fiber to the ferrule.

The present disclosure also relates to a device and method for mounting a fiber to a ferrule wherein the ferrule includes a first passageway portion sized only to receive a bare fiber without a coating or a buffer layer, a second passageway portion sized to receive the fiber including the coating, but no buffer layer, and a smooth and continuous transition between the first and the second passageway portions.

