Patent Description:
Fiber optic communication systems are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities (e.g., data and voice) to customers. Fiber optic communication systems employ a network of fiber optic cables to transmit large volumes of data and voice signals over relatively long distances. Optical fiber connectors are an important part of most fiber optic communication systems. Fiber optic connectors allow two optical fibers to be quickly optically connected and disconnected.

A typical fiber optic connector includes a ferrule assembly supported at a front end of a connector housing. The ferrule assembly includes a ferrule and a hub mounted to a rear end of the ferrule. A spring is used to bias the ferrule assembly in a forward direction relative to the connector housing. The ferrule functions to support an end portion of at least one optical fiber (in the case of a multi-fiber ferrule, the ends of multiple fibers are supported). The ferrule has a front end face at which a polished end of the optical fiber is located. When two fiber optic connectors are interconnected, the front end faces of their respective ferrules abut one another and the ferrules are forced together by the spring loads of their respective springs. With the fiber optic connectors connected, their respective optical fibers are coaxially aligned such that the end faces of the optical fibers directly oppose one another. In this way, an optical signal can be transmitted from optical fiber to optical fiber through the aligned end faces of the optical fibers. For many fiber optic connector styles, alignment between two fiber optic connectors is provided through the use of a fiber optic adapter that receives the connectors, aligns the ferrules and mechanically holds the connectors in a connected orientation relative to one another.

A fiber optic connector is often secured to the end of a corresponding fiber optic cable by anchoring a tensile strength structure (e.g., strength members such as aramid yarns, fiberglass reinforced rods, etc.) of the cable to the connector housing of the connector. Anchoring is typically accomplished through the use of conventional techniques such as crimps or adhesive. Anchoring the tensile strength structure of the cable to the connector housing is advantageous because it allows tensile load applied to the cable to be transferred from the strength members of the cable directly to the connector housing. In this way, the tensile load is not transferred to the ferrule assembly of the fiber optic connector. If the tensile load were to be applied to the ferrule assembly, such tensile load could cause the ferrule assembly to be pulled in a proximal direction against the bias of the connector spring thereby possibly causing an optical disconnection between the connector and its corresponding mated connector. Fiber optic connectors of the type described above can be referred to as pull-proof connectors. In other connector styles, the tensile strength layer of the fiber optic cable can be anchored to the hub of the ferrule assembly.

Connectors are typically installed on fiber optic cables in the factory through a direct termination process. In a direct termination process, the connector is installed on the fiber optic cable by securing an end portion of an optical fiber of the fiber optic cable within a ferrule of the connector. After the end portion of the optical fiber has been secured within the ferrule, the end face of the ferrule and the end face of the optical fiber are polished and otherwise processed to provide an acceptable optical interface at the end of the optical fiber. A direct termination is preferred because it is fairly simple and does not have losses of the type associated with a spliced connection.

A number of factors are important with respect to the design of a fiber optic connector. One aspect relates to ease of manufacturing and assembly. Another aspect relates to connector size and compatibility with legacy equipment. Still another aspect relates to the ability to provide high signal quality connections with minimal signal degradation.

<CIT> teaches a fiber optic assembly with the features of the preamble of claim <NUM>.

One problem is to provide a fiber optic assembly which solves at least one of the above mentioned problems and to provide a method for producing such a fiber optic assembly.

The solution is a fiber optic assembly with the features of claim <NUM> and a method with the features of claim <NUM> or <NUM>. Further preferred embodiments are disclosed in the dependent claims.

<FIG> and <FIG> illustrate a ferrule assembly <NUM> which can be used in the present fiber optic assembly. The ferrule assembly <NUM> includes a ferrule <NUM> and an optical fiber stub <NUM> secured to the ferrule <NUM>. The optical fiber stub <NUM> can be referred to as a "first optical fiber. " The ferrule <NUM> includes a front end <NUM> positioned opposite from a rear end <NUM>. The front end <NUM> preferably includes an end face <NUM> at which an interface end <NUM> of the optical fiber stub <NUM> is located. The ferrule <NUM> defines a ferrule bore <NUM> that extends through the ferrule <NUM> from the front end <NUM> to the rear end <NUM>. The optical fiber stub <NUM> includes a first portion <NUM> secured within the ferrule bore <NUM> and a second portion <NUM> that extends rearwardly from the rear end <NUM> of the ferrule <NUM>. The second portion <NUM> can be referred to as a "pigtail" or as a "free end portion.

The ferrule <NUM> is preferably constructed of a relatively hard material capable of protecting and supporting the first portion <NUM> of the optical fiber stub <NUM>. In one embodiment, the ferrule <NUM> has a ceramic construction. In other embodiments, the ferrule <NUM> can be made of alternative materials such as Ultem, thermoplastic materials such as Polyphenylene sulfide (PPS), other engineering plastics or various metals. In example embodiments, the ferrule <NUM> has a length L1 in the range of <NUM>-<NUM> millimeters (mm), or in the range of <NUM>-<NUM>.

The first portion <NUM> of the optical fiber stub <NUM> is preferably secured by an adhesive (e.g., epoxy) within the ferrule bore <NUM> of the ferrule <NUM>. The interface end <NUM> preferably includes a polished end face accessible at the front end <NUM> of the ferrule <NUM>.

Referring to <FIG>, the ferrule bore <NUM> has a stepped-configuration with a first bore segment <NUM> having a first diameter d1 and a second bore segment <NUM> having a second diameter d2. The second diameter d2 is larger than the first diameter d1. A diameter step <NUM> provides a transition from the first diameter d1 to the second diameter d2. The first bore segment <NUM> extends from the front end <NUM> of the ferrule <NUM> to the diameter step <NUM>. The second bore segment <NUM> extends from the diameter step <NUM> toward the rear end <NUM> of the ferrule <NUM>. The ferrule bore <NUM> also includes a conical transition <NUM> that extends from the second bore segment <NUM> to the rear end <NUM> of the ferrule <NUM>. In certain embodiments, the first diameter d1 is about <NUM> microns with a tolerance of +<NUM> micron. In certain embodiments, the second diameter d2 can be about <NUM> microns so as to accommodate a coated optical fiber, or about <NUM> microns so as to accommodate a coated and buffered optical fiber. In one example, d1 is in the range of <NUM>-<NUM> microns and d2 is in the range of <NUM>-<NUM> microns.

The first portion <NUM> of the optical fiber stub <NUM> includes a bare fiber segment <NUM> that fits within the first bore segment <NUM> of the ferrule <NUM> and a coated fiber segment <NUM> that fits within the second bore segment <NUM> of the ferrule <NUM>. The bare fiber segment <NUM> is preferably bare glass and, as shown at <FIG>, includes a core <NUM> surrounded by a cladding layer <NUM>. In a preferred embodiment, the bare fiber segment <NUM> has an outer diameter that is no more than. <NUM> microns smaller than the first diameter d1. In certain embodiments, the coated fiber segment <NUM> includes one or more coating layers <NUM> surrounding the cladding layer <NUM> (see <FIG>). In certain embodiments, the coating layer or layers <NUM> can include a polymeric material such as acrylate having an outer diameter in the range of about <NUM>-<NUM> microns. In still other embodiments, the coating layer/layers <NUM> can be surrounded by a buffer layer <NUM> (e.g., a tight or loose buffer layer) (see <FIG>) having an outer diameter in the range of about <NUM>-<NUM> microns.

The second portion <NUM> of the optical fiber stub <NUM> preferably has a length L2 that is relatively short. For example, in one embodiment, the length L2 of the second portion <NUM> is less than the length L1 of the ferrule <NUM>. In still other embodiments, the length L2 is no more than <NUM>, or is no more than <NUM>, or is no more than <NUM>. In still other embodiments, the length L2 of the second portion <NUM> is in the range of <NUM>-<NUM>, or in the range of <NUM>-<NUM>, or in the range of <NUM>-<NUM>, or in the range of <NUM>-<NUM>, or in the range of <NUM>-<NUM>, or in the range of <NUM>-<NUM>, or less than <NUM>, or less than <NUM>, or in the range of <NUM>-<NUM>.

<FIG> outlines a process for manufacturing the ferrule assembly <NUM> of <FIG>. The manufacturing process begins at step <NUM> where the ferrule <NUM> is fed to a processing station or location. It will be appreciated that the ferrule <NUM> can be fed by an automated feed mechanism such as a bowl feed mechanism.

Once the ferrule <NUM> has been selected and fed or otherwise moved to the processing station, the inner diameter of the ferrule <NUM> is preferably measured (see step <NUM>). For example, the first diameter d1 defined by the first bore segment <NUM> of the ferrule bore <NUM> is preferably measured. An automated ferrule handler (e.g., a gripper/holder <NUM> as shown schematically at <FIG>) can receive the ferrule <NUM> from the automated feed mechanism and can hold and/or manipulate the ferrule <NUM> during measurement.

Once the first diameter d1 of the ferrule bore <NUM> has been determined, an optical fiber suitable for insertion within the ferrule is selected (see step <NUM>). Preferably, a plurality of fiber spools 60a-60d is provided at the processing station. Each of the fiber spools 60a-60d includes a separate optical fiber 62a-62d. Each of the optical fibers 62a-62d preferably has a different cladding outer diameter. It is desirable to select the optical fiber 62a-62d having a cladding outer diameter that is closest to the measured diameter d1 of the ferrule <NUM>. In certain embodiments, the measured first diameter d1 is no more than. <NUM> microns larger than the cladding outer diameter of the selected optical fiber 62a-62d.

To enhance core concentricity with respect to the outer diameter of the ferrule <NUM>, it is desirable for the optical fibers 62a-62d to be high precision optical fibers in which parameters such as cladding outer diameter and core-to-cladding concentricity are manufactured to relatively tightly tolerance. In certain embodiments, each of the optical fibers 62a-62d has an outer cladding diameter manufactured within a tolerance of +/-. <NUM> microns and also has a core-to-cladding concentricity offset less than or equal to. <NUM> microns (i.e., the center of the core is offset from the center of the cladding diameter by no more than. <NUM> microns). The ferrule <NUM> is also preferably manufactured to relatively precise tolerance specifications. For example, in one embodiment, the diameter d1 of the ferrule has a dimension of <NUM> microns plus <NUM> micron, minus <NUM> microns. Additionally, the ferrule <NUM> can have a fiber bore to outer diameter concentricity offset less than or equal to <NUM> micron (i.e., the center of the ferrule bore is offset from the center of the outer diameter of the ferrule by no more than <NUM> micron). By using a precision ferrule in combination with a precision optical fiber, and by having several different sized precision optical fibers from which to select the optical fiber to be inserted in the ferrule, it is possible to optimize concentricity of the optical fiber within the ferrule <NUM> without rotational tuning and even more so with rotational tuning. In one economically reasonable embodiment, four fibers of known diameters of <NUM> microns, <NUM> microns, <NUM> microns, and <NUM> microns could be employed to match the ferrule inner diameter to within <NUM> to <NUM> microns. By using this fiber selection process as part of the manufacturing process, it is possible for all of the ferrule assemblies <NUM> output from the manufacturing process to have a measured first diameter d1 that is no more than. <NUM> microns larger than the cladding outer diameter of the selected optical fiber 62a-62d. Those that fall outside of the tolerance can be rejected, but because of the process only a relatively small number may fall outside of the tolerance thereby enhancing the cost effectiveness of the process. In other embodiments, the ferrule assemblies <NUM> manufactured and output according to the process can have measured first diameters d1 that on average are no more than. <NUM> microns larger than the cladding outer diameters of the selected optical fiber 62a-62d.

Once the optical fiber 62a-62d of the appropriate diameter has been selected, the optical fiber is cut to length to form the stub optical fiber <NUM> (see step <NUM>). In certain embodiments, the cut optical fiber <NUM> has a length less than <NUM> microns. In other embodiments, the optical fiber <NUM> has a length less than <NUM> microns, or less than <NUM> microns, or less than <NUM> microns, or less than <NUM> microns. In still other embodiments, the cut optical fiber has a length in the range of <NUM>-<NUM> microns.

At step <NUM>, the optical fiber <NUM> is stripped. By stripping the optical fiber <NUM>, the bare fiber segment <NUM> is exposed. The bare fiber segment <NUM> preferably includes a glass core <NUM> and cladding <NUM> as shown at <FIG>. The cutting and stripping steps can be automated.

After stripping of the optical fiber <NUM>, epoxy is dispensed into the ferrule bore <NUM> of the ferrule <NUM> (see step <NUM>), and the optical fiber <NUM> is inserted into the ferrule bore <NUM>. Because of the relatively tight tolerance between the first diameter d1 of the bare fiber segment <NUM> of the optical fiber stub <NUM> and the first portion <NUM> of the fiber bore <NUM>, surface tension between the epoxy within the ferrule bore <NUM> and the optical fiber stub <NUM> provides a self-centering function that assists in centering the bare fiber segment <NUM> within the first bore segment <NUM>. Such fiber insertion is indicated at step <NUM> of the process. The optical fiber stub <NUM> is inserted into the ferrule bore <NUM> through the rear end <NUM> of the ferrule <NUM>. During insertion, the optical fiber stub <NUM> is oriented such that the bare fiber segment <NUM> leads the optical fiber stub <NUM> through the ferrule <NUM>. After insertion, an end portion of the bare fiber segment <NUM> projects outwardly from the end face <NUM> of the ferrule <NUM>. The epoxy delivery and fiber insertion steps can be automated. During such steps, the ferrule can be held by the automated ferrule handler.

At step <NUM>, the ferrule assembly <NUM> is cured (e.g., oven cured), cooled and cleaved. It is noted that the curing process is particularly efficient because the ferrule <NUM> can be directly heated and the heat does not need to pass through a connector body or other structure surrounding the ferrule <NUM>. Similarly, the cooling process is efficient since only the ferrule <NUM> and the optical fiber stub <NUM> need to be cooled. Cleaving can be conducted using a laser or a mechanical cleaving tool. The curing, cooling and cleaving steps can be automated.

Once the optical fiber stub <NUM> has been cleaved adjacent the end face <NUM> of the ferrule <NUM>, the cleaved interface end <NUM> of the optical fiber <NUM> can be polished as indicated at step <NUM>. It will be appreciated that the polishing process can include multiple polishing steps using different polishing pads and polishing compounds having different degrees of abrasiveness. Because the ferrule assembly <NUM> is not connected to an extended length of cable, downward vertical polishing pressure can be applied without side loading from a cable. The absence of an extended length of cable coupled to the ferrule <NUM> also allows the ferrule assembly <NUM> to be rotated about its axis <NUM> during the polishing process. In certain embodiments, the ferrule assembly <NUM> can be rotated about its axis <NUM> at a rate of at least <NUM> rotations per minute, or at least <NUM> rotations per minute, or at least <NUM> rotations per minute, or at least <NUM> rotations per minute.

<FIG> and <FIG> show the ferrule end face <NUM> and the interface end <NUM> of the optical fiber <NUM> being polished using a rotating polishing table <NUM> that rotates about an axis <NUM>. A polishing pad <NUM> can be provided on the rotating polishing table <NUM>. In other embodiments, rather than rotating, the polishing table <NUM> may oscillate, reciprocate, move along a random orbit path, or otherwise move. Additionally, during the polishing process, it may be desirable to rotate the ferrule <NUM> about its axis of rotation <NUM> as described above.

As shown at <FIG> and <FIG>, a mechanical polishing process is used to polish the end face <NUM> of the ferrule and the interface end <NUM> of the optical fiber stub <NUM>. In other embodiments, a laser can be used to both cleave and polish/process the interface end <NUM> of the optical fiber stub <NUM>. When processing the end <NUM> of the optical fiber stub <NUM> with a laser, it may be desirable to rotate the ferrule <NUM> about its axis <NUM> as described above.

The above-described polishing steps can be automated. During polishing, the ferrule <NUM> can be held by the automated ferrule handler. In certain embodiments, the automated handler can include a rotational drive <NUM> for rotating the ferrule <NUM> about its axis <NUM> during polishing or other steps disclosed herein here rotation of the ferrule <NUM> about its center axis is desired.

During the polishing process, it is desirable to interrupt polishing and provide tuning of the ferrule assembly <NUM> (see step <NUM>). It will be appreciated that tuning is a process where an offset direction of the core <NUM> is established and an indication of the core offset direction is provided on the ferrule <NUM>. The indication of the core offset direction can include any number of techniques such as printing a mark on the ferrule <NUM>, etching a mark on the ferrule <NUM>, or otherwise marking the ferrule <NUM>. The core offset direction is the direction in which the core <NUM> is offset from a centerline (e.g., axis <NUM>) of the ferrule <NUM>.

As shown at <FIG>, the ferrule assembly <NUM> can be tuned by shining a light <NUM> through a rear end of the optical fiber stub <NUM> such that the light is conveyed through the optical fiber stub <NUM> and out the interface end <NUM> of the optical fiber stub <NUM>. A camera <NUM> or other structure can be used to view and monitor the light output through the fiber core <NUM> at the end <NUM> so as to determine the core position. The ferrule assembly <NUM> is then rotated about its axis <NUM> while the light <NUM> continues to be directed through the optical fiber stub <NUM> and the camera <NUM> continues to view the end <NUM> of the optical fiber stub <NUM>. As the ferrule assembly <NUM> is rotated about its axis <NUM>, the core <NUM> of the optical fiber stub <NUM> changes elevations relative to a horizontal line H (see <FIG>) that intersects the centerline <NUM> of the ferrule <NUM>.

<FIG> is a graph illustrating the height of the core <NUM> relative to the horizontal line H as the ferrule <NUM> is rotated about its centerline axis <NUM>. As shown at <FIG>, the maximum core height <NUM> is indicative of an offset direction <NUM> of the core <NUM> relative to the axis <NUM> of the ferrule assembly <NUM>. The axis <NUM> of the ferrule assembly <NUM> is defined by the outer diameter of the ferrule <NUM>. Once the core offset direction <NUM> has been established, the ferrule <NUM> can be marked accordingly such that the offset direction can be identified at a later time in the manufacturing process. For example, as shown at <FIG>, a marking <NUM> is provided in direct alignment with the core offset direction <NUM>. In other embodiments, the marking could be offset <NUM>° from the core offset direction <NUM> or at other locations on the ferrule <NUM>. When the ferrule assembly <NUM> is later installed in a connector body, the marking <NUM> is used to orient the core offset a desired location relative to the connector body. For example, in a preferred embodiment, the core offset direction <NUM> is oriented at the twelve o'clock position relative to the connector body. The marking <NUM> can also be used to orient the core offset relative to a hub that is subsequently mounted on the ferrule <NUM>. The hub can include a keying structure for ensuring that the ferrule is mounted at a desired rotational position within the connector body such that the core offset is oriented at a desired rotational position relative to the connector body.

Because the ferrule assembly <NUM> is tuned prior to insertion within a connector body and/or prior to mounting the hub on the ferrule <NUM>, tuning can be provided at an infinite number of increments (i.e., the marking location can be chosen from an infinite number of rotational/circumferential positions about the centerline of the ferrule) to provide precise alignment of the marking <NUM> with the core offset direction <NUM>. In another embodiment, the marking location can be chosen from a discrete number of rotational/circumferential positions about the centerline of the ferrule, where the number of discrete rotational/circumferential positions is at least <NUM>, or at least <NUM>, or at least <NUM>, or at least <NUM>, or at least <NUM>. In other examples, the ferrule assembly <NUM> is tuned after at least a portion of the hub is mounted on the ferrule and the hub can define a discrete number of rotational/circumferential positions. In such examples, a core offset marking can be provided on the hub. The tuning step can be automated and rotation of the ferrule <NUM> during tuning can be achieved by the automated ferrule handler.

After tuning, the polishing process is completed at step <NUM> and various inspections are conducted at step <NUM>. The inspections can include a corporate workmanship standard inspection in which the end <NUM> of the optical fiber stub <NUM> is inspected with a microscope to insure that there are no unacceptable scratches, pits or chips on the end face. The end face <NUM> of the optical fiber stub <NUM> and the end face <NUM> of the ferrule <NUM> can also be inspected and analyzed to insure the end faces comply with certain geometry specifications for the end faces. Finally, a continuity check can be conducted by which a light is shined through the optical fiber stub <NUM> to make sure the optical fiber stub <NUM> is capable of transmitting light. After the continuity check has been completed, a dust cap can be installed on the ferrule <NUM> and the ferrule assembly <NUM> can be packaged at shown at step <NUM>. The various steps described above can be automated.

<FIG> illustrate a fiber optic cable and connector assembly <NUM> in accordance with the principles of the present disclosure. The fiber optic cable and connector assembly <NUM> includes a fiber optic connector <NUM> having a connector body <NUM>. The connector body has a front end <NUM> and a back end <NUM>. The ferrule assembly <NUM> is positioned at least partially within the connector body <NUM>. Specifically, the ferrule assembly <NUM> is positioned with the ferrule <NUM> positioned adjacent to the front end <NUM> of the connector body <NUM>. The fiber optic connector <NUM> further includes a boot <NUM> mounted adjacent the back end <NUM> of the connector body <NUM>. As used herein, the word "adjacent" means at or near. In a preferred embodiment, the connector <NUM> is compatible with existing connectors, fiber optic adapter, patch panels and fiber optic cables.

The fiber optic cable and connector assembly <NUM> further includes a fiber optic cable <NUM> that extends through the boot <NUM>. The fiber optic cable <NUM> includes a jacket <NUM> and an optical fiber <NUM> positioned within the jacket <NUM>. The optical fiber <NUM> can be referred to as a "second optical fiber. " The optical fiber <NUM> is optically connected at a fusion splice <NUM> to the optical fiber <NUM> of the ferrule assembly <NUM>. The fusion splice <NUM> is positioned at a splice location <NUM> spaced from the rear end <NUM> (i.e., the base) of the ferrule <NUM>. In one embodiment, the splice location <NUM> is within the connector body <NUM> and is positioned no more than <NUM> from the rear end <NUM> of the ferrule <NUM>. The fusion splice <NUM> is preferably a factory fusion splice. A "factory fusion splice" is a splice performed at a manufacturing facility as part of a manufacturing process. In one embodiment, the fiber optic connector <NUM> fully complies with Telcordia GR-<NUM> or similar stringent industry or customer specifications. In other examples, the splice can be a field splice.

Referring to <FIG>, the connector body <NUM> includes a front piece <NUM> and a rear piece <NUM>. The front piece <NUM> forms a front interface end of the fiber optic connector <NUM> and the rear piece <NUM> is configured to allow strength members <NUM> (e.g., aramid yarn, fiberglass or other strength members capable of providing tensile reinforcement to the fiber optic cable <NUM>) of the fiber optic cable <NUM> are anchored. In certain embodiments, the strength members <NUM> can be secured to the rear piece <NUM> of the connector body <NUM> with a mechanical retainer such as a crimp sleeve. In other embodiments, adhesive or other means can be used to secure the strength members <NUM> to the connector body <NUM>.

Still referring to <FIG>, the front and rear pieces <NUM>, <NUM> of the connector body <NUM> interconnect together by a connection such as a snap-fit connection, an adhesive connection or other type of connection. When the front and rear pieces <NUM>, <NUM> are connected together, a spring <NUM> and a hub <NUM> are captured between the front and rear pieces <NUM>, <NUM>. The hub <NUM> is secured over the rear end <NUM> of the ferrule <NUM>. The hub <NUM> also covers the splice location <NUM> such that the fusion splice <NUM> is located within the hub <NUM>. In the depicted embodiment, an intermediate layer <NUM> (e.g., a coating layer, an over mold layer, or other layer) is provided between the fusion splice <NUM> and the hub <NUM>. The spring <NUM> is captured within a spring pocket <NUM> defined by the rear piece <NUM> and functions to bias the hub <NUM> and the ferrule assembly <NUM> which is carried with the hub <NUM> in a forward direction relative to the connector body <NUM>. The hub <NUM> is a structure secured on the ferrule <NUM> such that the ferrule <NUM> and the hub <NUM> move together as a unit. In certain embodiments, the hub <NUM> provides structure against which the bias of the spring <NUM> can be applied to bias the hub <NUM> and the ferrule <NUM> forwardly relative to the connector body <NUM>. The hub <NUM> also includes structure that interferes with an internal structure (e.g., a stop) of the connector body <NUM> to limit the forward movement of the ferrule <NUM> and to prevent the ferrule <NUM> from being pushed out of the front of the connector body <NUM> by the spring <NUM>. The hub <NUM> and the splice location <NUM> can be positioned within the spring pocket <NUM>. The boot <NUM>, the rear piece <NUM> and the spring <NUM> all can have internal dimensions (e.g., inner diameters) larger than an outer dimension (e.g., an outer diameter) of the cable <NUM> such that during assembly/manufacturing the boot <NUM>, the rear piece <NUM> and the spring <NUM> can be slid back over the jacket <NUM> to provide space/clearance for splicing and application of the hub over the spice <NUM>.

In the depicted embodiment, the fiber optic connector <NUM> is shown as a standard SC-type connector. As such, the fiber optic connector <NUM> is adapted to be received within an SC-type fiber optic adapter that is used to couple two of the fiber optic connectors together to provide an optical connection there between. The fiber optic connector <NUM> includes a release sleeve <NUM> that is slidably mounted on the connector body <NUM>. When the fiber optic connector <NUM> is inserted within a fiber optic adapter, shoulders of the connector body <NUM> are engaged by latches of the fiber optic adapter to retain the fiber optic connector <NUM> within the fiber optic adapter. To release the fiber optic connector <NUM> from the fiber optic adapter, the release sleeve <NUM> is slid rearwardly relative to the connector body <NUM> thereby causing the latches of the fiber optic adapter to disengage from the shoulders of the connector body <NUM> such that the fiber optic connector <NUM> can be withdrawn from the fiber optic adapter. An example fiber optic adapter is disclosed at <CIT>.

In a preferred embodiment, the splice location <NUM> is relatively close to the rear end <NUM> of the ferrule <NUM>. For example, in one embodiment, the splice location <NUM> is no more than <NUM> from the ferrule <NUM>. In another embodiment, the splice location <NUM> is no more than <NUM> from the ferrule <NUM>. In still another embodiment, the splice location <NUM> is no more than <NUM> from the ferrule <NUM>. In further embodiments, the splice location is spaced <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM> or spaced <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>, or less than <NUM> from the ferrule <NUM>, or less than <NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>, or <NUM>-<NUM> from the ferrule <NUM>.

To the extent that in some embodiments of the present disclosure a hub may not be provided, the splice location <NUM> (i.e., the interface between the two optical fibers <NUM>, <NUM>) is preferably located in the region that would normally be occupied by a hub. In certain embodiments, the splice location is provided between the base of the ferrule <NUM> and the rear end of the spring <NUM>. In certain embodiments, the splice location <NUM> is within the spring chamber <NUM>. In certain embodiments, the spring <NUM> biases the ferule <NUM> toward a forward-most position (i.e., a distal-most position or non-connected position) and during a connection with another connector the spring <NUM> allows the ferrule <NUM> to move rearwardly from the forward-most position, against the bias of the spring <NUM>, to a rearward position (i.e., proximal position or connected positioned). In certain embodiments, the splice location <NUM> is positioned between forward and rearward ends 228a, 228b of the spring <NUM> when the ferrule is in the forward-most position, and is also positioned between the forward and rearward ends 228a, 228b of the spring <NUM> when the ferrule <NUM> is in the rearward position.

In certain embodiments, the hub <NUM> has a polymeric construction that has been over molded over the rear end of the ferrule <NUM> and over the splice location <NUM>. By protecting the fusion splice <NUM> within the hub <NUM> at a location in close proximity to the ferrule <NUM>, it is possible to manufacture a fiber optic connector that is relatively short in length. In a preferred embodiment, the fiber optic connector <NUM> has a length L3 that is less than <NUM>. It will be appreciated that the length L3 of the fiber optic connector <NUM> is measured from the front end <NUM> of the ferrule <NUM> to a rear end <NUM> of the boot <NUM>. In certain embodiments, a portion <NUM> of the hub <NUM> that extends rearward of the ferrule <NUM> has a length L4 that is shorter than the length L1 of the ferrule <NUM>. In certain examples, the splice location <NUM> is within <NUM> of the rear end of the ferrule <NUM>. Providing the splice location <NUM> within <NUM> of the rear end of the ferrule <NUM> assists in designing the fiber optic connector in compliance with standard industry or customer side load and connector length specifications (e.g., GR-<NUM> side load and length requirements).

The boot <NUM> is shown press-fit over the rear piece <NUM> of the connector body <NUM>. Specifically, the boot <NUM> is press-fit over the location where the strength members <NUM> are attached to the connector body <NUM>. It will be appreciated that the boot <NUM> has a tapered, flexible configuration that provides the optical fiber <NUM> with bend radius protection when a side load is applied to the fiber optic connector <NUM> through the fiber optic cable <NUM>.

In one embodiment, the fusion splice <NUM> is a factory fusion splice having a splice related insertion loss of. <NUM> decibels or less,. <NUM> decibels or less, or. <NUM> decibels or less in the <NUM> nanometer to <NUM> nanometer signal wavelength range. Furthermore, in preparing the optical fibers for the fusion splice <NUM>, an active alignment system can be utilized to accurately align the optical fibers <NUM>, <NUM>. Example active alignment systems are sold by Sumitomo, Furukawa, Vytran, 3SAE, and Fujikura. In certain embodiments, the active alignment system can ensure that the centers of the cores of the optical fibers <NUM>, <NUM> being spliced are offset by no more than <NUM> microns by the alignment system prior to splicing. The alignment system can utilize cameras that view the cores of the optical fibers <NUM>, <NUM> along viewing lines that are perpendicular to one another (e.g., a top view and a side view).

As described above, in certain embodiments, the optical fiber stub <NUM> can be manufactured using a precision fiber having tightly toleranced parameters such as core to cladding concentricity and cladding outer diameter variation. In this regard, in certain embodiments, the optical fiber stub <NUM> can be different (e.g., can have a different construction, different mechanical characteristics , different physical attributes, different optical performance characteristics, different degrees of precision, etc.) than the optical fiber <NUM> of the fiber optic cable. For example, the optical fiber stub <NUM> can be a more precisely manufactured optical fiber than the optical fiber <NUM> of the fiber optic cable <NUM> (i.e., the stub fiber is manufactured according to tighter tolerances than the cable optical fiber <NUM>). For example, in certain embodiments, the optical fiber stub <NUM> can have better average core to cladding concentricity than the optical fiber <NUM>. Also, the outer diameter of the cladding of the optical fiber stub <NUM> can be more precisely toleranced that the outer diameter of the cladding of the optical fiber <NUM>. Further, the optical fiber stub <NUM> can have a different (e.g., lower) fiber cut-off wavelength than the optical fiber <NUM>. Moreover, the optical fiber stub <NUM> can have different cladding mode suppression characteristics as compared to the optical fiber <NUM>. For example, as compared to the optical fiber <NUM>, the optical fiber stub <NUM> can have a construction adapted to provide enhanced cladding mode suppression for suppressing modal interference. Example optical fibers having constructions adapted to reduce/suppress modal interference are disclosed at <CIT>; <CIT>; and <CIT>.

It is well known in the art that splices can introduce losses (e.g., insert loss, return loss). However, the fiber optic cable and connector assembly <NUM> of the present disclosure includes various features that provide excellent performance despite the presence of an internal splice. Such features include: a) precise core-to-core alignment of the spliced optical fibers; b) precise centering of the optical fiber stub <NUM> within the ferrule bore <NUM>, precise tuning of the core offset direction within the connector body, and precise centering of the ferrule bore <NUM> within the ferrule <NUM>.

In certain examples, the fiber optic connector <NUM> can be in full compliance with the requirements of Telcordia GR-<NUM>. Specific sections of Telcordia GR-<NUM> in which the fiber optic connector <NUM> can be in compliance include sections pertaining to transmission with applied load, installation tests, and the post-condensation thermal cycle test.

<FIG> shows a process for manufacturing a patch cord formed by mounting fiber optic connectors <NUM> on opposite ends of the fiber optic cable <NUM>. At step <NUM> of the method, the fiber optic cable <NUM> is coiled and the components of the fiber optic connectors <NUM> are staged. Next, at step <NUM>, the ends of the jacket <NUM> of the fiber optic cable <NUM> are then cut and slit, and the strength layer <NUM> is trimmed. As so prepared, end portions of the optical fiber <NUM> extend outwardly from each end of the jacket <NUM>. The end portions of the optical fiber <NUM> are then stripped, cleaned and cleaved (e.g., laser cleaved) (see step <NUM>). During stripping, cleaning and cleaving, the end portions of the optical fiber <NUM> can be gripped in a holder <NUM> (e.g., a holding clip or other structure) (see <FIG>).

At step <NUM>, ferrule assemblies <NUM> are fed (e.g., bowl fed) to a holder <NUM> or holders which grip/hold the ferrule <NUM>. An example holder <NUM> is shown at <FIG>. In some examples, the ferrules <NUM> are oriented within the holders <NUM> with the tuning marks <NUM> at the twelve o'clock position so that the ferrule assemblies <NUM> can be subsequently loaded into their corresponding connector bodies <NUM> at the twelve o'clock position. In this way, it is ensured that the core offset direction is oriented at the uppermost position/sector of each connector. While the twelve o'clock position is preferred, the core offset direction can be established within the connector body at other rotational positions as well.

While each ferrule <NUM> is held by the holder <NUM>, the free end of the optical fiber stub <NUM> is stripped, cleaned (e.g., arc cleaned) and cleaved (e.g., laser cleaved) (see step <NUM>). It will be appreciated that ferrule assemblies <NUM> are prepared for each end of the patch cable.

Once the fibers have been stripped, cleaned and cleaved, the optical fiber stub <NUM> of each ferrule assembly <NUM> is coarsely aligned with a corresponding end portion of optical fiber <NUM> (see <FIG>), and then precisely aligned (see <FIG>). Precise alignment of the optical fibers can be accomplished using an active alignment device. In using the active alignment device, the fiber <NUM> is held within the holders <NUM> with an end portion of the fiber <NUM> projecting outwardly from one end of the holder <NUM> (as shown at <FIG>, the cable <NUM> projecting from the opposite end of the holder <NUM> has been omitted). Also, the ferrule <NUM> is held within a pocket of the holder <NUM> while the fiber <NUM> projects from the base of the ferrule <NUM> and is not contacted directly by the holder <NUM> or any other structure. The holder <NUM> can include a clip or other structure having two or more pieces that clamp and hold the ferrule <NUM> during active alignment of the fibers <NUM>, <NUM>. The pocket of the holder <NUM> can include an internal structure (e.g., a V-groove, semicircular groove, etc. for aligning/positioning the ferrule <NUM>). The end portions of the fibers are preferable unsupported (e.g., not in direct contact with a structure such as a v-groove). In one example, the fiber <NUM> projects less than <NUM> from the base end of the ferrule <NUM>. This relatively short length facilitates the active alignment process. In certain examples, the center axis of the fiber <NUM> is angled no more than. <NUM> degrees relative to the center line of the ferrule. This also assists the active alignment process. While ideally there is no angular offset between the center axis of the fiber <NUM> and the ferrule <NUM>, the short stub length of the fiber <NUM> assist in minimizing the effect during active alignment of any angular offset that may exist. Robotics are preferably used to manipulate the holders <NUM>, <NUM> to achieve axial alignment between the cores of the fibers <NUM>, <NUM>. Because alignment does not rely on contacting extended lengths of the fibers <NUM>, <NUM> with alignment structure such as v-grooves, the splice location can be provided in close proximity to the base of the ferrule <NUM> (e.g., within <NUM> of the base). In certain embodiments, only splices in which the centers of the cores of the optical fibers <NUM>, <NUM> being spliced are offset by no more than <NUM> microns are acceptable, and splices falling outside of this parameter are rejected. In other embodiments, the average core offset for fibers spliced by the process is less than. <NUM> microns.

After precise axial alignment has been achieved, a shielding unit <NUM> is lowered over the splice location <NUM> and a fusion splice machine <NUM> (e.g., an arc treatment machine) is used to fuse the optical fibers <NUM>, <NUM> together. The shielding unit <NUM> includes shielding portions for shielding the ferrule <NUM> and coated portions of the optical fibers <NUM>, <NUM> intended to be spliced together. The shielding structure <NUM> can have a ceramic construction, Polyether ether ketone (PEEK) construction, another heat resistant plastic construction or other type of heat resistant construction. Preferably, the shielding structure <NUM> includes a gap g through which an arc or other energy source from the fusion splice machine <NUM> can pass to fusion splice the optical fibers <NUM>, <NUM> together. Preferably the gap g is <NUM>-<NUM>, or <NUM>-<NUM>. <FIG> shows the shielding structure <NUM> in the raised orientation and <FIG> shows the shielding structure in a shielding position. The shielding structure can include side walls <NUM> that protect the sides of the ferrule <NUM> and extend along the lengths of optical fibers <NUM>, <NUM>, and cross-walls <NUM> that extend between the side walls <NUM>. The cross-walls <NUM> extend across to the optical fibers <NUM>, <NUM> (e.g., transverse to the optic fibers <NUM>, <NUM>) and include slots <NUM> for receiving the optical fibers <NUM>, <NUM>. The side walls <NUM> also protect the portions of the fibers <NUM>, <NUM> adjacent the splice location and the holders <NUM>, <NUM>. The cross-walls <NUM> protect the fibers <NUM>, <NUM>, the rear end <NUM> of the ferrule <NUM> and the holders <NUM>, <NUM>. A bridge section extends across the gap g between the cross-walls <NUM>. Step <NUM> of <FIG> is representative of the alignment, shielding and fusion splicing operations.

After the fusion splice has been completed, a protective layer <NUM> can be placed, applied or otherwise provided over the optical fibers <NUM>, <NUM> in the region between the rear end <NUM> of the ferrule <NUM> and a buffered/coated portion of the optical fiber <NUM>. In one example, the protective layer <NUM> extends completely from the rear end <NUM> of the ferrule <NUM> to a coated and buffered portion of the optical fiber <NUM>. As depicted, the coated and buffered portion of the optical fiber <NUM> includes coatings in the form of a <NUM>-<NUM> micron acrylate layers which cover the glass portion of the optical fiber, and a buffer layer <NUM> (e.g., a loose or tight buffer tube) having an outer diameter ranging from <NUM>-<NUM>,<NUM> microns. At <FIG>, the protective layer <NUM> is shown extending over the splice location <NUM> completely from the rear end <NUM> of the ferrule <NUM> to the buffer layer of the optical fiber <NUM>. In one embodiment, the protective layer <NUM> is generally cylindrical (see <FIG>) and has a diameter slightly larger than the buffer layer and generally the same as a major diameter of the conical transition <NUM> of the ferrule bore <NUM>. In other embodiments, the protective layer <NUM> can have a truncated conical configuration (see <FIG>) with a major diameter generally equal to the outer diameter of the ferrule <NUM> and a minor diameter generally equal to the outer diameter of the buffer layer of the optical fiber <NUM>. It will be appreciated that the protective layer <NUM> can be applied using an over molding technique. Alternatively, coating, spraying, laminating or other techniques can be used to apply the protective layer.

In certain embodiments, the protective layer <NUM> is made of a material that is softer (e.g., has a lower hardness) than the material used to manufacture the hub <NUM>. In certain embodiments, the unstripped portion of the optical fiber <NUM> has an inner coating layer that surrounds the cladding layer, and the protective layer <NUM> has mechanical attributes such as softness/hardness that substantially match or are comparable to the mechanical attributes of the inner coating layer of the unstripped portion of the optical fiber <NUM>. In certain embodiments, the protective layer <NUM> can be made of a thermoplastic material, a thermoset material (a material where cross-linking is established during heat curing), other types of cross-linked materials or other materials. Example materials include acrylates, epoxies, urethanes, silicones and other materials.

At least some of the materials can be UV curable (i.e., the materials cure when exposed to ultraviolet radiation/light). One example material includes a UV curable splicing compound such as DSM-<NUM> which is sold by DSM Desotech, Inc. of Elgin Illinois. In certain embodiments, an injection molding process (e.g., a thermoplastic injection molding process) can be used to apply and form the protective layer <NUM> about the splice location <NUM>.

Once the protective layer <NUM> has been applied and cured, the hub <NUM> is preferably over molded over the protective layer <NUM> as shown at <FIG>. The hub <NUM> is preferably over molded over the rear end <NUM> of the ferrule <NUM> and also over the splice location <NUM>. <FIG> shows a mold assembly <NUM> mold pieces 400a, 400b having an inner shape that matches the outer shape of the hub <NUM>. The mold assembly <NUM> shown in <FIG>, discussed below, may also be used to form the hub <NUM>. Preferably, a polymeric material is injected from an injection machine <NUM> into a cavity <NUM> defined by the mold pieces 400a, 400b to over mold the polymeric material over the splice location <NUM> and the rear end <NUM> of the ferrule <NUM>. In certain embodiments, the hub <NUM> is molded by injecting a UV curable material into the mold, and the mold pieces 400a, 400b are made of a UV transmissive material (e.g., Teflon) such that UV light/radiation can be transmitted through the mold pieces 400a, 400b for curing the hub <NUM> within the mold.

Referring back to <FIG>, the hub <NUM> is shaped to include a flange <NUM> that engages the spring <NUM>. Additionally, the hub <NUM> is configured to support the rear end <NUM> of the ferrule <NUM> within the connector body <NUM>. Furthermore, a forward end or flange <NUM> of the hub <NUM> is configured to engage a shoulder <NUM> within the connector body <NUM> to halt forward movement of the ferrule assembly <NUM> caused by the forward bias provided by the spring <NUM>. In this way, the flange <NUM> functions to retain the ferrule <NUM> within the connector body <NUM>. <FIG> shows the ferrule assembly <NUM> after the hub <NUM> has been over molded over the rear end <NUM> of the ferrule <NUM>, over the splice location <NUM> and over a buffered portion of the optical fiber <NUM> of the fiber optic cable <NUM>. Step <NUM> of <FIG> is representative of the over molding operations.

In certain embodiments, the hub <NUM> can be made of a thermoplastic material, a thermoset material (a material where cross-linking is established during heat curing), other types of cross-linked materials, or other materials. Example materials include acrylates, epoxies, urethanes, silicones and other materials. At least some of the materials can be UV curable (i.e., the materials cure when exposed to ultraviolet radiation/light). As described above, in certain embodiments, an injection molding process (e.g., a thermoplastic injection molding process) can be used to apply and form the hub <NUM> about the splice location <NUM> and ferrule <NUM>. In certain embodiments, a hot melt material can be injected into the mold to form the hub <NUM>. The use of hot melt materials (e.g., hot melt thermoplastic materials) and/or UV curable materials allows the hub over molding process to be conducted at relatively low pressures (e.g., less than <NUM>,<NUM> MPa (<NUM> pounds per square inch)) and at relatively low temperatures (e.g., less than <NUM> degrees Celsius). In certain examples, curing can take place at temperatures less than <NUM> degrees Celsius, or less than <NUM> degrees Celsius, or at room temperature, and at pressures less than <NUM>,<NUM> MPa or less than <NUM>,<NUM> kPa or <NUM>,<NUM> kPa (pressures less than <NUM> psi or pressures less than <NUM> or <NUM> psi).

After the hubs <NUM> have been over molded at each end of the fiber optic cable <NUM>, the other components of the fiber optic connectors <NUM> are assembled over the ferrule assembly <NUM> and the hub <NUM> (see step <NUM> at <FIG>). Additionally, the strength members of the fiber optic cable <NUM> are attached to the rear ends of the connector bodies <NUM> of the fiber optic connectors <NUM>. A continuity check can be conducted for the patch cable and dust caps are positioned over the ferrules <NUM> (see step <NUM> at <FIG>). Finally, the patch cords are packaged and labeled (see step <NUM> of <FIG>). It will be appreciated that any and/or all of the above connector manufacturing steps can be automated. Robotics can improve the consistency and quality of the connectorization process and automation can assist in lowering labor related costs.

Various additional fiber optic connector embodiments are described below. It will be appreciated that the various materials, properties, dimensions and other features described above with respect to components such as the ferrule, the optical fibers, the hub, connector body and the boot are also applicable to like components described below.

<FIG> illustrate another fiber optic cable and connector assembly 200a in accordance with the principles of the present disclosure. The fiber optic cable and connector assembly 200a includes a fiber optic connector 202a having a connector body 204a in which a ferrule 22a is mounted. The ferrule 22a supports an optical fiber stub 24a having a bare optical fiber segment 46a spliced to a bare fiber segment 291a of an optical fiber 216a of an optical cable. The optical fiber 216a includes a coated portion 293a. A loose buffer tube 221a surrounds and protects at least a portion of the coated portion 293a of the optical fiber 216a. The bare fiber segment 46a is spliced to the bare fiber segment 291a at a splice location 218a. A generally cylindrical protective layer 232a is coated or overmolded over the splice location 218a. More specifically, the protective layer 232a is shown extending from a rearward end of the ferrule 22a to a forward end of the buffer tube 221a. The protective layer 232a fully encapsulates the bare fiber segments 46a, 291a and also encapsulates a portion of a coated fiber segment 48a of the optical fiber stub 24a and a portion of the coated portion 293a of the optical fiber 216a. The protective layer 232a further encapsulates the forward end of the loose buffer tube 221a. In certain embodiments, some of the material forming the protective layer 232a flows around the exterior of the buffer tube 221a and also flows inside the buffer tube 221a between the interior of the buffer tube 221a and the coated portion 293a of the optical fiber 216a. A hub 230a is over molded around the rearward end of the ferrule <NUM> and encapsulates and protects the protective layer 232a as well as the splice location 218a within the protective layer 232a. The hub 230a is bonded or otherwise secured/attached to the ferrule 22a. A spring 228a biases the hub 230a and the ferrule 222a in a forward direction. As shown at <FIG>, the hub 232a extends from the rearward end of the ferrule 22a to the loose buffer tube 221a and fully encapsulates the protective layer 232a. Additionally, a rearward portion of the hub 232a surrounds and bonds to an exterior surface of the buffer tube 221a to prevent the buffer tube 221a from being pulled from the connector. Because both the protective layer 232a and the hub 230a are bonded or otherwise attached to the buffer tube 221a, the buffer tube 221a has enhanced pull-out characteristics. Such characteristics are further enhanced if the protective layer 232a is bonded to both the outside and the inside of the buffer tube 221a.

In the embodiment of <FIG>, the portion of the hub 230a attached to the outer surface of the buffer tube 221a has an axial length that is longer than a corresponding axial length of the portion of the protective layer 232a that is attached to the buffer tube 221a. <FIG> show another fiber optic cable and connector assembly 200b having the same basic construction as the fiber optic cable and connector assembly 200a except a protective layer 232b has been lengthened to increase the contact length between the protective layer 232b and a buffer tube 221b, and a hub 230b has been modified to accommodate the lengthened protective layer 232b. In this way, the portion of the protective layer 232b attached to the buffer tube 221b is longer than the portion of the hub 232b that engages and is bonded to or attached to the buffer tube 221b. The embodiment of <FIG> is particularly advantageous for applications where the protective layer <NUM> has better adhesion characteristics with respect to the buffer tube <NUM> as compared to the material of the hub 230b. In contrast, the embodiment of <FIG>, <FIG> and 28A is preferred for embodiments where the material of the hub 230a has enhanced bonding characteristics with respect to the buffer tube 221a as compared to the material of the protective layer 232a. In both of the embodiments, the rear portion of the hub engages and circumferentially surrounds (i.e., shuts-off against) the buffer tube.

<FIG> show a further fiber optic cable and connector assembly 200c in accordance with the principles of the present disclosure. The fiber optic cable end connector assembly 200c has structure adapted to enhance retention of a buffer tube 221c within a fiber optic connector 202c. As shown at <FIG>, the fiber optic connector 202c includes a crimp ring <NUM> mechanically crimped adjacent a forward end of the buffer tube 221c. The crimp ring <NUM> includes a recess or receptacle in the form of an annular groove <NUM> that extends around a perimeter of the crimp ring <NUM>. The fiber optic connector 202c further includes a hub 230c over molded over the crimp ring <NUM> and the forward end of the buffer tube 221c. The hub 230c includes an annular projection <NUM> that projects radially inwardly into the annular groove <NUM> of the crimp ring <NUM>. In this way, a mechanical interlock exists between the hub 230c and the crimp ring <NUM>. The mechanical interlock resists relative axial movement between the crimp ring <NUM>. The crimp ring has a forward end that abuts against a protective layer 232c that protects a splice location 218c between an optical fiber stub 24c and an optical fiber <NUM>. The optical fiber stub 24c has forward ends supported in a ferrule 22c and rearward end portions that project rearwardly from the ferrule 22c. The optical fiber 216c corresponds to a fiber optic cable. The protective layer 232c protects a bare fiber segment 291c and a coated portion 293c of the optical fiber 216c as well as a coated fiber segment 48c and a bare fiber segment 46c of the optical fiber stub 24c. The hub 230c surrounds and is coupled to (i.e., boded to , affixed to , attached to) a rearward end of the ferrule 22c and fully encloses the protective layer 232c, the forward end of the buffer tube 221c and the crimp ring <NUM>. A rearward end of the hub 230c forms an annular buffer tube contact surface that shuts off against an exterior of the buffer tube 221c at a location rearward of the crimp ring <NUM>.

In the embodiments of <FIG>, <FIG> and <FIG>, the hubs have rear portions that circumferentially engage their corresponding buffer tubes. Thus, the molds used to form the hubs shut off on the buffer tubes. In contrast, <FIG> show a further fiber optic cable and connector assembly 200d in accordance with the principles of the present disclosure where a hub 230d of a fiber optic connector 202d does not engage a corresponding buffer tube 221d of the fiber optic cable and connector assembly 200d. Instead, the fiber optic cable and connector assembly 200d includes an elongated protective layer 232d that encapsulates a forward end of the buffer tube 221d and also encapsulates the splice location 218d. The protective layer 232d defines an annular groove <NUM> that extends around its perimeter at a location adjacent the splice location 218d. The hub 230d is over molded over the protective layer 232d and includes an annular projection <NUM> that fills and fits within the annular groove <NUM>. This way, a mechanical interlock is formed between the protection layer 232d and the hub 230d to prevent a relative axial movement between the hub 230d and the protective layer 232d. The protective layer 232d is preferably affixed or otherwise bonded to the exterior surface of the buffer tube 221d and also can fill a portion of the buffer tube 221d so as to bond with an interior surface of the buffer tube 221d. The protective layer 232d projects rearwardly beyond a rearward end of the hub 230d. In this way, the rearward end of the hub 230d circumferentially surrounds and contacts the protective layer 232d but does not contact the buffer tube 221d. Thus, a mold for forming the hub 230d is configured to shut-off around the protective layer 232d rather than the buffer tube 221d. In other embodiments more than one inner lock structure can be provided between the hub 230d and the protective layer 232d. Additionally, the inner lock structures can be provided at different locations along the length of the protective layer 232d. The protective layer 232d has an outer diameter larger than an outer diameter of the buffer tube 221d.

<FIG> show another fiber optic cable and connector assembly 200e in accordance with the principles of the present disclosure. The fiber optic cable and connector assembly 200e includes a fiber optic connector 202e having a ferrule 22e supporting an optical fiber stub 24e. The fiber optic cable and connector assembly 200e also includes an optical fiber 216e spliced to the optical fiber stub 24e at a splice location 218e. The optical fiber <NUM> corresponds to an optical cable having a buffer tube 221e. The optical fiber stub 24e includes a coated fiber segment 48e and a bare fiber segment 46c (i.e., a bare glass segment). The optical fiber <NUM> includes a bare fiber segment 291e and a coated portion 293e. A protective layer 232e extends from a rear end of the ferrule 22e to a forward end of the buffer tube 221e. In the depicted embodiment, the protective layer 232e is generally cylindrical and has a maximum outer diameter that is smaller than an inner diameter of the buffer tube 221e. The protective layer 232e protects the splice location 218e and the bare fiber segments 46e and 291e. The protective layer 232e also encapsulates portions of the coated fiber segment 48e and the coated portion 293e. A hub 230e is over molded over the rear end of the ferrule 22e, and over the forward end of the buffer tube 221e. The protective layer 232e is fully enclosed or encapsulated within the hub 230e. A mold used to form the hub 230e closes on the buffer tube 221e. This way, the rear portion of the hub 230e circumferentially surrounds and is affixed to an outer surface of the buffer tube 221e. A front portion of the hub 230e circumferentially surrounds and is coupled to the rear end of the ferrule 22e.

<FIG> show a sequence for splicing an optical fiber stub 24f supported by a ferrule 22f to an optical fiber 216f of a fiber optic cable. The optical fiber stub 24f includes a bare fiber segment 46f and a coated fiber segment 48f. The optical fiber 216f includes a bare fiber segment 291f and a coated portion 293f. The fiber optic cable also includes a buffer tube 221f that surrounds the coated portion 293f of the optical fiber 216f. <FIG> shows the optical fiber 216f coaxially aligned with the optical fiber stub 24f in preparation for splicing. <FIG> shows the optical fiber stub 24f spliced the optical fiber 216f. <FIG> shows a protective layer 232f over molded or otherwise applied over a splice location 218f between the optical fiber 216f and the optical fiber stub 24f. The protective layer 232f extends from a rearward end of the ferrule 22f to a forward end of the buffer tube 221f. <FIG> shows a hub frame <NUM> (e.g., a case or framework) mounted over the rearward end of the ferrule 22f and the forward end of the protective layer 232f. The hub frame <NUM> is preferably a pre-molded part that can be inserted over the ferrule 22f. In certain embodiments, the hub frame <NUM> is manufactured of a relatively hard plastic material such as a polyamide material. As shown at <FIG>, the hub frame <NUM> includes a forward ring <NUM> that mounts over the ferrule 22f and a rearward ring <NUM> positioned over the protective layer 232f. A plurality of axial ribs <NUM> connect the forward ring <NUM> to the rearward ring <NUM>. An inner diameter of the forward ring <NUM> preferably closely matches the size of the outer diameter of the ferrule 22f. A front end of the forward ring <NUM> can include a plurality of chamfered surfaces <NUM> adapted for seating within a connector body when the assembly is spring biased to a forward position within a connector. A plurality of openings <NUM> are defined between the axial ribs <NUM>. For example, in the depicted embodiment, two axial ribs <NUM> spaced about <NUM>° apart from one another are provided between the forward and rearward rings <NUM>, <NUM>. In other embodiments, more than two axial ribs <NUM> can be provided. The rearward ring <NUM> has an inner diameter that is substantially larger than an outer diameter of the protective layer 232f. In this way, an annular gap <NUM> is defined between the inner surface of the rearward ring <NUM> and the outer surface of the protective layer 232f. The hub frame <NUM> can be made of a material that is harder and more robust that the material used to form a rear portion of the hub. The hub frame <NUM> can be over molded on the ferrule 22f and can include an inner portion that fills or fits within a slot/recess 23f of the ferrule 22f to enhance retention of the hub frame <NUM> on the ferrule 22f. The hub frame <NUM> can be over molded using an over molding process having higher process temperatures and pressures than an over molding process used to form a portion of the hub (e.g., hub portion <NUM>) that covers the splice location. In this way, the hub is provided with a robust construction without exposing the splice location to high processing temperatures and pressures.

After the hub frame <NUM> has been mounted over the ferrule 22f as shown at <FIG>, an over molded hub portion <NUM> can be over molded within and over the hub frame <NUM> to form a composite hub 230f that is coupled to the ferrule 22f and contains the splice location 218f. The over molded portion <NUM> preferably fills void regions between the axial ribs <NUM> and also fills the annular gap <NUM> between the rearward ring <NUM> and the protective layer 232f. In the depicted embodiment, the over molded hub portion <NUM> completely encapsulates the protective layer 232f and includes a rearward portion that closes around the buffer tube 221f. The hub frame <NUM> and the over molded hub portion <NUM> cooperate to define the composite hub 230f that is anchored to the ferrule 22f. The over molded hub portion flows into the gaps between the annular ribs <NUM> of the hub frame <NUM> and bonds to an exterior surface of the ferrule and functions to lock the hub frame <NUM> in place relative to the ferrule 22f. The axial ribs <NUM> are shown embedded within the over molded hub portion <NUM> and a portion of the over molded hub portion forms a ring <NUM> that surrounds the axial ribs <NUM>. The ring <NUM> abuts against a backside of the forward ring <NUM> and has an exterior surface that is generally flush with an exterior surface of the forward ring <NUM>. The front end of the forward ring <NUM> is not covered by the over molded portion <NUM>. In this way, the forward end of the forward ring <NUM> forms a front nose of the composite hub 230f.

It will be appreciated that the composite hub 230f can be used in any of the fiber optic connectors in accordance with the principles of the present disclosure. Additionally, in certain embodiments, the over molded hub portion <NUM> is formed of a hot melt adhesive or other material that can be applied and cured at relatively low molding temperatures and pressures. In certain embodiments, the overmolded hub portion <NUM> is made of a material having different material properties than the material of the hub frame <NUM>. For example, the overmolded hub portion <NUM> can be softer or more resilient than the hub frame <NUM>. The composite nature of the hub 230f simplifies the molding operation.

The composite construction of the composite hub 230f relies on the hub frame <NUM> to provide mechanical strength and precision. The composite construction of the composite hub 230f relies on the over molded hub portion <NUM> for securement of the composite hub 230f to the ferrule 22f, for securement of the composite hub 230f to the buffer tube 221f and for providing additional protection with respect to the splice location 218f and the bare fiber segments 46f, 291f.

It will be appreciated that various aspects of the present disclosure are also applicable to multi-fiber connectors. For example, <FIG> shows a multi-fiber ferrule <NUM> supporting a plurality of optical fiber stub having a plurality of optical fibers <NUM>. The ferrule <NUM> can include openings <NUM> in which alignment pins can be mounted to configure the ferrule <NUM> as a male component. The optical fibers <NUM> are preferably aligned along a row within the ferrule <NUM> and have end faces that are polished and accessible at a forward end <NUM> of the ferrule <NUM>. Rear portions <NUM> of the optical fibers <NUM> project rearwardly from a rear end <NUM> of the ferrule <NUM>. Similar to previous embodiments, the optical fibers <NUM> can be precision optical fibers having different properties or characteristics than the optical fibers of the fiber optic cable to which the optical fiber stub is to be spliced.

In certain embodiments, the optical fibers <NUM> of the optical fiber stub are spliced to the optical fibers of the cable at a location in close proximity to the rear end <NUM> of the ferrule <NUM>. For example, in one embodiment, the splice location is within <NUM> millimeters of the rear end <NUM> of the ferrule <NUM>. In other embodiments, the splice location is within <NUM> millimeters of the rear end of <NUM> of the ferrule <NUM>. In still other embodiments, the splice location is in the range of <NUM>-<NUM> millimeters of the rear end <NUM> of the ferrule <NUM>.

<FIG> shows the ferrule <NUM> mounted within a multi-fiber fiber optic connector <NUM>. The connector <NUM> includes a connector body <NUM> having a front piece 432a and a rear piece 432b. A boot <NUM> is mounted to a rear end of the rear piece 432b of the connector body <NUM>. The front end <NUM> of the ferrule <NUM> is accessible at the front end of the connector body <NUM>. A removable dust cap <NUM> is shown mounted over the front end <NUM> of the ferrule <NUM>. A release sleeve <NUM> is mounted over the connector body <NUM>. A spring <NUM> biases the ferrule <NUM> in a forward direction. To use the fiber optic connector <NUM>, the dust cap <NUM> is removed thereby allowing the front end of the connector to be inserted within a corresponding fiber optic adapter (e.g., an MPO adapter). As is known in the art, the fiber optic connector <NUM> (e.g., an MPO connector) snaps within the fiber optic adapter. By pulling back on the release sleeve <NUM>, the fiber optic connector <NUM> can be released from the fiber optic adapter.

<FIG> show a sequence of steps for preparing a multi-fiber fiber optic cable <NUM> to be spliced to the optical fibers <NUM> of the ferrule <NUM> of <FIG>. The multi-fiber cable <NUM> can include a plurality of optical fibers <NUM> positioned within a jacket <NUM>. A strength layer <NUM> for providing tensile reinforcement to the cable <NUM> can be positioned between the jacket <NUM> and the optical fibers <NUM>. In certain embodiments, the strength layer <NUM> is made of a tensile reinforcing material such as aramid yarn.

As shown at <FIG>, the outer jacket <NUM> has been stripped to expose about <NUM>-<NUM> millimeters of the optical fibers <NUM>. The strength layer <NUM> is shown separated from the fibers <NUM> and folded back over the jacket <NUM>. The optical fibers <NUM> have been sorted and arranged into a row. A material such as tape <NUM> can be used to hold the coated optical fibers <NUM> in the desired order. In the depicted embodiment, the optical fibers <NUM> include twelve fibers arranged in a planar 12x1 array. In other embodiments, other types of instant adhesive can be used to secure the optical fibers <NUM> in the desired order sequence.

<FIG> shows the strength layer <NUM> trimmed to a suitable length for securement to the multi-fiber connector <NUM>. In one embodiment, the strength layer <NUM> is trimmed to a length of about <NUM>-<NUM> millimeters.

<FIG> shows a thermoplastic over molded section <NUM> is molded over the ordered optical fibers <NUM>. In one embodiment, the over molded section <NUM> is separated from the cable jacket <NUM> by a distance d1 in the range of about <NUM>-<NUM> millimeters. In certain embodiments, the over molded section <NUM> has a length d2 of about <NUM>-<NUM> millimeters. In certain embodiments, d1 can equal about <NUM> millimeters and d2 can equal about <NUM> millimeters.

<FIG> shows the spring <NUM> of the multi-fiber connector <NUM> inserted over the optical fibers <NUM> of the cable <NUM>. <FIG> shows coatings of the optical fibers <NUM> stripped from the optical fibers <NUM>. In this way, bare glass portions of the optical fibers <NUM> are exposed. In certain embodiments, the bare glass portions can start at a point spaced a distance d3 of about <NUM>-<NUM> millimeters from the end of the cable jacket <NUM>. After the stripping step, the bare optical fibers can be cleaned and inspected for defects. <FIG> shows the optical fibers <NUM> after the optical fibers <NUM> have been cleaved (e.g., laser cleaved). In certain embodiments, after cleaving, the bare fiber portions of the optical fibers <NUM> have a length d4 of about <NUM> millimeters. After cleaving, the fiber optic cable <NUM> is ready to be spliced to the optical fibers <NUM> supported by the multi-fiber ferrule <NUM>.

The assembly of the multi-fiber ferrule <NUM> and the optical fibers <NUM> is shown at <FIG>. To access the depicted assembly, the ferrule <NUM> can be bowl fed and picked and placed at the output of the bowl. It will be appreciated that the front end <NUM> of the ferrule <NUM> has been preprocessed and the end faces of the optical fibers <NUM> at the front end <NUM> have been pre-polished. Additionally, in the bowl, the end face <NUM> is preferably protected by a dust cap. An automated system can scan and read information provided on the ferrule <NUM> (or on the dust cap) that identifies the ferrule <NUM>. The automated system can also remove the packed dust cap, rotate the ferrule <NUM> in a vision system to accurately find the window on the ferrule, and can accurately position the ferrule in a gripper/carrier without touching or damaging the front face <NUM> of the ferrule <NUM>.

<FIG> show steps for preparing the optical fibers <NUM> of the multi-fiber ferrule <NUM> for splicing to the optical fibers of the multi-fiber cable <NUM>. To prepare the ferrule <NUM> and the optical fibers <NUM> for splicing, coatings of the optical fibers <NUM> are stripped to expose bare glass portions of the optical fibers <NUM> as shown at <FIG>. Also, the optical fibers can be cleaned and inspected for defects. As shown at <FIG>, the bare optical fibers are then cleaved to a length d5 of preferably <NUM> millimeters or less. As shown at <FIG>, buffered portions of the optical fibers project outwardly from the rear side of the ferrule <NUM> by a distance less than about <NUM> millimeter. In the depicted embodiment of <FIG>, a boot <NUM> is shown schematically positioned within the ferrule <NUM> adjacent the rear end <NUM>. The boot <NUM> is configured to provide bend radius protection and strain relief to the optical fibers <NUM> adjacent the rear end <NUM> of the ferrule <NUM>. Preferably, the boot <NUM> projects no more than <NUM> millimeters rearwardly from the rear end <NUM> of the ferrule <NUM>. In the depicted embodiment, a rear end of the boot is flush with the rear end <NUM> of the ferrule <NUM>. In other embodiments, the rear end of the boot <NUM> can be recessed within the ferrule <NUM> so as to be forwardly offset from the rear end <NUM> of the ferrule. This way, the boot <NUM> provides protection of the optical fibers <NUM> without interfering with subsequent splicing operations that take place in close proximity to the rear end <NUM> of the ferrule <NUM>.

<FIG> shows the stub optical fibers <NUM> of the ferrule <NUM> being fusion spliced to the optical fibers <NUM> of the multi-fiber cable <NUM>. A fusion splicing tray <NUM> is used to provide alignment of the optical fibers <NUM>, <NUM> and to protect various components from exposure to the fusion splicing arc. The tray has a length L, a width W and a height H. The width W extends in a direction parallel to the optical fibers <NUM>, <NUM> when the optical fibers <NUM>, <NUM> are supported on the tray <NUM>. As shown at <FIG>, when viewed in top plan view, the tray <NUM> has a narrowed, waist region <NUM> (i.e., a narrowed region or a waist region) at an intermediate location along the length L. The narrow, waist region <NUM> has a reduced width W1 that is smaller than the width w of the tray <NUM> at the ends of the tray <NUM>. The narrow region <NUM> is provided by notches <NUM> that extend into a main body of the tray <NUM> at opposite sides of the tray <NUM>. In other embodiments, only one of the notches may be provided to form the narrowed region <NUM>.

The narrowed region <NUM> corresponds to a splicing region/zone <NUM> where the optical fibers <NUM>, <NUM> are routed across the tray <NUM> and fusion spliced together. Alignment structures in the form of v-grooves <NUM> are provided at a top side of the tray <NUM> adjacent the narrowed region <NUM> for supporting the optical fibers <NUM>, <NUM> and for coaxially aligning the optical fibers <NUM>, <NUM>. In other embodiments, active alignment equipment of the type previously described can also be used to coaxially align the optical fibers. The narrowed region <NUM> provides clearance for allowing the optical fibers <NUM> to be spliced to the optical fibers <NUM> in close proximity to the rear end <NUM> of the ferrule <NUM>.

The tray <NUM> also includes structure for preventing debris from contaminating the splicing region <NUM>. As shown at <FIG> and <FIG>, arc/fusion splicing electrodes <NUM> fit within a slot <NUM> that extends along the length L of the tray <NUM>. The slot <NUM> narrows to a narrowed portion <NUM> as the slot passes the region where the v-grooves <NUM> support the optical fibers <NUM>, <NUM>. The narrowed portion <NUM> corresponds to the spicing region <NUM>. The electrodes <NUM> are positioned on opposite sides of the splicing region <NUM> of the tray <NUM>. Free ends of the optical fibers <NUM>, <NUM> that are intended to be spliced together overhang the narrowed portion <NUM> of the slot <NUM>. Contamination reduction slots <NUM> are positioned adjacent to each of the sets of v-grooves <NUM>. Specifically, the contamination reduction slots <NUM> are positioned between the v-grooves <NUM> and the narrowed portion <NUM> of the slot <NUM>. Preferably, the contamination reduction slots <NUM> extend completely through the height H of the tray <NUM> and allow contamination to fall through the tray <NUM> rather than contaminating the ends of the fibers prior to splicing. Rails <NUM> are positioned between the contamination reduction slots <NUM> and the narrowed portion <NUM> of the slot <NUM>. The rails <NUM> are preferably slightly recessed relative to the depth of the v-grooves <NUM>. For example, as shown at <FIG>, top sides <NUM> of the rail <NUM> are positioned lower than valleys <NUM> of the v-grooves <NUM>. It will be appreciated that the depth of the slot <NUM> extends substantially below the top sides <NUM> of the rails <NUM>. The rails <NUM> function to catch debris before the debris enters the slot <NUM>.

The slot <NUM> is preferably deep enough for an electric arc to be passed between the electrodes <NUM> and used to heat and fuse together the ends of the optical fibers <NUM>, <NUM>. By recessing the electrode <NUM> within the slot <NUM>, the tray <NUM> functions to shield the ferrule <NUM> and other components from heat associated with the arc. Prior to fusing the ends of the optical fibers together via the arc generated across the electrodes <NUM>, a short burst of electric arc can be used to clean the splice zone. The v-grooves can be defined in a ceramic portion of the tray <NUM> (or the tray can be fully made of ceramic or like materials) and can be used to provide final alignment of the optical fibers <NUM>, <NUM>. The tray <NUM> can also protect the areas outside the splice zone from unwanted exposure to the electric arc. The arc provided between the electrode <NUM> reflows the glass of the optical fibers and thereby provides a splice thereinbetween. In other embodiments, alternative heat sources may be used as well.

After the fusion splicing process has been completed, the components are removed from the tray <NUM> and the fusion splice area is preferably over molded with a protective coating material such as an ultraviolet cured polymer. The ultraviolet cured polymer is preferably cured to ensure that it is stable to temperatures exceeding <NUM>° C. The ferrule <NUM> is then configured to be a female component (see <FIG>) or a male component (see <FIG>). A spring clip can be mounted adjacent the back side of the ferrule as needed for either the female configuration or the male configuration of the connector.

Subsequently, the ferrule <NUM> and the spring are loaded into the front portion 432a of the connector housing <NUM> (see <FIG>) and the rear portion 432b of the connector housing <NUM> is secured to the front portion 432a thereby retaining the spring and ferrule therein (see <FIG>). The strength layer <NUM> of the cable <NUM> is then secured (e.g., crimped with crimp ring <NUM>) to a rear stub <NUM> of the rear portion 432b of the connector housing <NUM> (see <FIG> and <FIG>). Next, the boot <NUM> is installed over the crimp band as shown at <FIG> and the dust cap <NUM> is installed over the front end of the connector <NUM> as shown at <FIG>.

<FIG> show a sequence for splicing an optical fiber stub <NUM> supported by a ferrule <NUM> to an optical fiber <NUM> of a fiber optic cable. The optical fiber stub <NUM> includes a bare fiber segment <NUM> and a coated fiber segment <NUM>. The optical fiber <NUM> includes a bare fiber segment <NUM> and a coated portion <NUM>. The fiber optic cable also includes a buffer tube <NUM> that surrounds the coated portion <NUM> of the optical fiber <NUM>. <FIG> shows the optical fiber <NUM> coaxially aligned with the optical fiber stub <NUM> in preparation for splicing. <FIG> shows the optical fiber stub <NUM> spliced to the optical fiber <NUM>. <FIG> shows a protective layer <NUM> over molded or otherwise applied over a splice location <NUM> between the optical fiber <NUM> and the optical fiber stub <NUM>. The protective layer <NUM> extends from a rearward end of the ferrule <NUM> to a forward end of the buffer tube <NUM>. <FIG> shows a body <NUM> having a front hub portion <NUM> and a rear hub portion <NUM>. The front hub portion <NUM> includes flat sides <NUM> and an inter lock portion <NUM>, such as a dove tail. In certain embodiments, the front hub portion <NUM> of the body <NUM> can be manufactured of a relatively hard plastic material such as a polyamide material. As shown at <FIG>, the front hub portion <NUM> is pre-molded (e.g., overmolded) over the ferrule <NUM> prior to the optical fiber stub <NUM> being spliced to the optical fiber <NUM>. Marking can be placed on the flat sides <NUM> of the front hub portion <NUM> to aid in tuning. In certain embodiments, the front hub portion <NUM> has <NUM> or <NUM> flats. The flat <NUM> closest to the core offset direction can be marked for later identification when the ferrule <NUM> assembly is loaded in a connector body. Thus, the marked flat <NUM> can be used to identify (either manually or automatically) the core offset direction of the ferrule <NUM>.

After the front hub portion <NUM> has been molded over the ferrule <NUM> and the fibers <NUM>, <NUM> have been spliced together, as shown at <FIG>, the rear hub portion <NUM> can be over molded within and over the front hub portion <NUM> to form a composite hub <NUM> that is coupled to the ferrule <NUM> and contains the splice location <NUM>. The rear hub portion <NUM> is overmolded to encapsulate the dove tail of the front hub portion <NUM> and the protective layer <NUM>. In the depicted embodiment, the rear hub portion <NUM> completely encapsulates the protective layer <NUM> and includes a rearward portion that closes around the buffer tube <NUM>. The front end of the front hub portion <NUM> is not covered by the rear hub portion <NUM>. In this way, the forward end of the front hub portion <NUM> forms a front nose of the composite hub <NUM>. <FIG> shows an alternative embodiment of the rear hub portion <NUM>. Referring to <FIG>, the ferrule <NUM> is shown without the rear hub portion <NUM> and the buffer tube <NUM> removed. <FIG> are side and cross-sectional views of <FIG>. <FIG> is a top view of <FIG> and <FIG> is a perspective view of the alternative embodiment. <FIG> are side and cross-sectional view of <FIG>.

It will be appreciated that the composite hub <NUM> can be used in any of the fiber optic connectors in accordance with the principles of the present disclosure. Additionally, in certain embodiments, the rear hub portion <NUM> is formed of a hot melt adhesive that can be applied and cured at relatively low molding temperatures and pressures. Rear hub portion <NUM> can also be formed from a UV curable material (i.e., the materials cure when exposed to ultraviolet radiation/light), for example, UV curable acrylates, such as OPTOCAST™ <NUM> manufactured by Electronic Materials, Inc. of Breckenridge, Colorado; ULTRA LIGHT-WELD® <NUM> manufactured by Dymax Corporation of Torrington, Connecticut; and <NUM>™ SCOTCH-WELD™ manufactured by <NUM> of St. Paul, Minnesota. The use of UV curable materials is advantageous in that curing can occur at room temperatures and at generally lower pressures (e.g. less than <NUM> kpsi, and generally between <NUM> - <NUM> kpsi). The availability of low pressure curing helps to ensure that the components, such as the optical fiber(s), being over molded are not damaged during the molding process. In certain embodiments, an injection molding process can be used to apply and form the rear hub portion <NUM> from a UV curable material about the protective layer <NUM> and the front hub portion <NUM>. In certain embodiments, the rear hub portion <NUM> is made of a material having different material properties than the material of the front hub portion <NUM>. For example, the rear hub portion <NUM> can be softer or more resilient than the front hub portion <NUM>. The composite nature of the hub <NUM> simplifies the molding operation. The front hub portion <NUM> can be over molded using an over molding process having higher temperatures and pressures than the over molding process used to form the rear hub portion <NUM>. The front hub portion can interlock with the ferrule <NUM>.

In some embodiments, the composite construction of the composite hub <NUM> relies on the front hub portion <NUM> to provide mechanical strength and precision and for securement of the composite hub <NUM> to the ferrule <NUM> (e.g., the front hub portion <NUM> is bonded to the ferrule <NUM>). In some embodiments, the composite construction of the composite hub <NUM> relies on the rear hub portion <NUM> for securement of the composite hub <NUM> to the buffer tube <NUM> and for providing additional protection with respect to the splice location <NUM> and the bare fiber segments <NUM>, <NUM>.

In one embodiment, the front hub portion <NUM> can be mounted (e.g., over molded) on the ferrule <NUM> prior to polishing, cleaning, cleaving, stripping, tuning, active alignment and splicing of the ferrule assembly. In this way, the front hub portion <NUM> can be used to facilitate handling and positioning of the ferrule <NUM> during the various processing steps. In one example, a flat of the front hub portion <NUM> can be marked for tuning purposes.

In one embodiment, the rear hub portion <NUM> can be overmolded to encapsulate the dove tail of the front hub portion <NUM> and the protective layer <NUM> in an injection mold assembly <NUM>, as shown in <FIG>. As shown, mold assembly <NUM> includes an upper mold assembly <NUM> and a lower mold assembly <NUM>. The upper mold assembly <NUM> includes an upper mold block <NUM> attached to and operated by the mold assembly <NUM> via an upper frame piece <NUM>. Likewise, the lower mold assembly <NUM> includes a lower mold block <NUM> attached to and operated by the mold assembly <NUM> via a lower frame piece <NUM>. The actuation of the frame pieces <NUM>, <NUM> may be manual or automatic.

In one embodiment, the upper and lower mold blocks <NUM>, <NUM> are formed from a UV light transmissive material, such as Dupont™ TEFLON® FEP <NUM> Fluoropolymer Resin. This material has been found to have sufficient UV light transmission characteristics above <NUM> wavelengths at thicknesses corresponding to those used for mold blocks <NUM>, <NUM> (e.g. about <NUM> - <NUM>% transmissivity for material thicknesses between <NUM>-<NUM> millimeters at UV wavelengths of <NUM> at an initial intensity of about <NUM> - <NUM> watts / square centimeter). Also, TEFLON® has beneficial properties that allow for the mold blocks <NUM>, <NUM> to be molded with complex mold cavity shapes while also being resistant to adhesion to the cured material in the mold cavities. This material also allows for the mold blocks <NUM>, <NUM> to have mating surfaces that are sufficiently formed to avoid undesirable flashing on the molded part.

The upper mold block <NUM> and the lower mold block <NUM> may have a plurality of cooperating cavity portions <NUM>, <NUM> for forming the rear hub portion <NUM>. As can be most easily seen at <FIG>, the upper mold block <NUM> has an upper cavity portion <NUM> that cooperates with a lower cavity portion <NUM> on the lower mold block <NUM>. As shown, the upper cavity portion <NUM> includes a mold cavity portion 714a, a ferrule securing portion 714b, and a buffer tube pocket portion 714c while lower cavity portion <NUM> includes a mold cavity portion 716a, a ferrule securing portion 716b, and a buffer tube pocket portion 716c. When the upper and lower mold blocks <NUM>, <NUM> are pressed against each other via operation of the frame pieces <NUM>, <NUM>, the upper and lower cavity portions <NUM>, <NUM> form a mold cavity with portions 714a, 716a, and secure the ferrule <NUM> with portions 714b, 716b. The buffer tube pockets 714c, 716c create a passageway for buffer tube <NUM> during the molding process.

It is noted that mold blocks <NUM>, <NUM> may include upper and lower vacuum channels <NUM>, <NUM>, connected to a vacuum source (not shown), for securing the ferrules <NUM> against portions 714b, 716b to prevent unwanted movement during the molding process. As shown, channels <NUM>, <NUM> extend along the mold blocks <NUM>, <NUM> to each of the cavity portions 714b, 716b. It is further noted that the contours of the mold cavity portions 714a, 716a match the shape of the full formed rear hub portion <NUM> shown in <FIG> and <FIG>. In the embodiment shown at <FIG>, there are twelve pairs of cooperating mold cavity portions <NUM>, <NUM> such that twelve rear hub portions <NUM> may be formed simultaneously by the mold assembly <NUM>.

As shown, the mold assembly <NUM> further includes a series of injection needles <NUM>. In one embodiment, there is one injection needle <NUM> for each mold cavity. However, more than one injection needle may be provided for each mold cavity. The injection needles <NUM> are for injecting uncured material for the rear hub portion <NUM> into the mold cavities formed once the mold blocks <NUM>, <NUM> have been pressed against each other. In one embodiment, the lower mold block <NUM> includes passageways <NUM> which provide a fluid communication path between the injection needles <NUM> and the corresponding mold cavities. It is noted that the injection needles <NUM> may be made from a material that is non-transmissive to UV light, such as a metal, in order to prevent unwanted or premature curing within the injection needle <NUM>.

Referring to <FIG>, a valve <NUM> having a passageway <NUM> is provided within the passageway <NUM> of the lower mold block <NUM>. In one embodiment, the valve <NUM> is made from a material that is non-transmissive to UV light, such as opaque silicone or EPDM rubber. Such a material will help to prevent uncured material within the valve <NUM> and/or injection needle <NUM> from being undesirably cured during the molding process. In one embodiment, the valve <NUM> is configured as a one-way valve such that uncured material may flow into the mold cavity through passageway <NUM>, but may not flow from the mold cavity back into the injection needle <NUM>.

In one embodiment, valve <NUM> is made from a flexible polymeric material and is configured such that passageway <NUM> opens when a threshold pressure exerted by the uncured material within injection needle <NUM> is exceeded, and closes when pressure is sufficiently reduced. In one embodiment, valve <NUM> is a slit-type valve. It is noted that <FIG> show the valve <NUM> in an open position with the passageway <NUM> being shown with an exaggerated size for the purpose of clarity. The combined features of valve <NUM> also result in a molded rear hub portion <NUM> that is free from legs or runners that would normally need to be removed from a molded product after the molding process.

Additionally, each injection needle <NUM> may be configured to be inserted through its respective valve <NUM> and into the cavity area 716a, 714a when injecting molding material into the cavities. In such a configuration, the injection needles <NUM> may be retracted out of the mold cavities after the cavities are sufficiently filled and before the curing process begins. It is also noted that mold assembly <NUM> may also be configured to draw a slight vacuum on the uncured material within the injection needles <NUM> after filling the mold cavity to help ensure that uncured material is removed further away from the area of UV light exposure.

As shown, the mold assembly <NUM> further includes a plurality of UV light fixtures <NUM> (728a, 728b, 728c). The UV light fixtures <NUM> are for directing UV light towards the mold cavity portions 714b, 716b such that UV sensitive material within the cavities can be cured during the molding process. In the embodiment shown, three UV lights are arranged to direct UV light onto each mold cavity from various angles. It is noted that more or fewer UV lights could be used. In the embodiment shown, the UV light fixtures <NUM> include LED bulbs that emit <NUM> nanometer (nm) ultraviolet light at <NUM> watts per square centimeter. It is noted that other wavelengths and intensities may be used, and that the chosen wavelength and intensity of the lights is generally a function of the selected materials used for the mold blocks and the rear hub portion <NUM>. Referring to <FIG>, a total of <NUM> sets of UV light fixtures 728a, 728b, 728c are provided for the twelve mold cavities. While <NUM> sets directly expose light on a particular mold cavity, an additional set of UV light fixtures is provided at each end of the mold blocks <NUM>, <NUM> to ensure that the outermost mold cavities are exposed to the same level of UV light as the inner mold cavities.

As most easily seen at <FIG>, the upper mold block <NUM> has a plurality of cavities <NUM> for receiving UV lights 728a. The UV lights 728a are oriented to direct light downward onto the upper cavity portion 714b. The lower mold block <NUM> has recesses <NUM> and <NUM> for receiving UV lights 728b and 728c, respectively. The recesses <NUM> and <NUM> are disposed angles due to the presence of the injection needles <NUM>, valves <NUM>, and the ejector pins (discussed later). It is noted that since the valves <NUM> and injection needles <NUM> may not UV light transmissive, that UV lights 728b and 728c must be oriented to ensure the mold cavity is sufficiently exposed to UV light around these components. As mentioned above, because the mold blocks <NUM>, <NUM> are UV light transmissive, the UV lights are able to cure the molded material within the mold cavities while the mold blocks <NUM>, <NUM> are closed together.

Once the mold material has been sufficiently cured to form the rear hub portions <NUM>, the vacuum that secures the ferrules may be discontinued and the mold blocks <NUM>, <NUM> may be separated. In order to facilitate removal of the composite hub <NUM> from the mold blocks <NUM>, <NUM>, the mold assembly <NUM> may be provided with an ejector assembly <NUM>. In one embodiment, the ejector assembly <NUM> includes an upper ejector assembly <NUM> located in the upper mold assembly <NUM> and a lower ejector assembly <NUM> in the lower mold assembly <NUM>. As shown, each of the ejector assemblies <NUM>, <NUM> includes a plurality of ejector pins <NUM>, <NUM> connected to a common support rail <NUM>, <NUM>. The number of ejector pins <NUM> corresponds to the number of mold cavities. Accordingly, the upper mold block has a passageway <NUM> for the ejector pins <NUM> while the lower mold block has a passageway <NUM> for the ejector pins <NUM>. To remove the hub <NUM> from the mold blocks <NUM>, <NUM>, the ejector pins <NUM>, <NUM> are driven into the passageways <NUM>, <NUM> until they contact and dislodge the ferrule portion <NUM> located within cavity portions 714b, 716b. The support rails <NUM>, <NUM> that drive the pins <NUM>, <NUM> may be either manually or automatically actuated. It is noted that the ejector pins <NUM>, <NUM> may be manufactured from a UV light transmissive material so as to minimize interference with the curing process. Examples of UV light transmissive materials for the ejector pins <NUM>, <NUM> are transparent glass and polycarbonate. It is also noted that the ejector pins can be removed or partially retracted away from the cavities in the mold blocks <NUM>, <NUM> during the curing process to reduce interference with UV light transmission.

Referring to <FIG>, an injection molding process <NUM> is shown in which mold assembly <NUM> may be used to form an overmolded ferrule and composite hub. In a first step <NUM>, ferrules with pre-molded collars, which may be spliced to buffered fibers of cable assemblies, are positioned over the cavities in the mold assembly. In a second step <NUM>, a vacuum is turned on to hold the ferrules and prevent unwanted movement in either axial or rotational modes. It is noted that the vacuum may be active before the ferrules with pre-molded collars are positioned over the cavities. In a third step <NUM>, once all of the desired cavities in the mold are filled, the mold blocks of the mold assembly are closed together. In another step <NUM>, EFD or similar dispensing units are used to deliver UV material into the mold cavities under low pressure through the injection needles and associated valves. The amount of material injected may be calculated or empirically determined using trials to optimize the fill volume without causing unwanted flash or other protrusions. In another step <NUM>, the UV lights are activated and turned on at an intensity and duration optimized to fully cure the materials with a minimum cycle time. In one embodiment, the cycle time is about <NUM> seconds when using a <NUM> UV light at <NUM> watts per square centimeter. In one embodiment, the intensity of the UV light is initially low, for example for the first <NUM> seconds of a <NUM> second cycle, and is then raised to a higher value. Such an approach is beneficial where the material to be cured may be sensitive to volatilization if exposed to the higher intensity value initially. In another step <NUM>, the mold blocks are separated. Ejector pins may be also be used during separation at the location of the ferrule to dislodge the overmolded ferrule and hub. In another step <NUM>, the overmolded ferrule and hub is withdrawn from the mold assembly. It is noted that other injection molding applications may be used with the above described mold assembly and process, and that the disclosure is not limited to injection molding parts and components relating to optical fiber technology.

<FIG> show the ferrule assembly <NUM> and hub <NUM> according to the claimed invention. The ferrule assembly <NUM> includes a ferrule <NUM> supporting an optical fiber stub <NUM>. The optical fiber stub <NUM> is fusion spliced to an optical fiber <NUM> of a fiber optic cable <NUM> at a splice location <NUM>. The hub <NUM> mounts to the rear end of the ferrule <NUM> and covers the splice location <NUM>. The hub <NUM> includes a front hub portion <NUM> and a rear hub portion <NUM>. The rear hub portion <NUM> includes an outer hub shell <NUM> defining an interior cavity <NUM>. The outer hub shell <NUM> includes an axial/longitudinal slot <NUM> that allows the outer hub shell <NUM> to be inserted laterally over the optical fiber stub <NUM> and the optical fiber <NUM> at the splice location <NUM> after the optical fiber stub <NUM> has been spliced to the optical fiber <NUM>. The outer hub shell <NUM> also includes a port <NUM> for allowing the outer hub shell <NUM> to be filled with an over mold material (e.g., a UV curable material, a hot melt material, a thermoplastic material, an epoxy material, a thermoset material, or other materials). The over mold material <NUM> is not shown at <FIG>, but is depicted at <FIG>. The outer hub shell <NUM> can function as a mold for shaping the over mold material <NUM> around the splice location <NUM> and along the lengths of the optical fiber <NUM> and the optical fiber stub <NUM>. A temporary mold piece can be used to cover the axial slot <NUM> as the over mold material <NUM> is injected into the outer hub shell <NUM> through the port <NUM>. The outer hub shell <NUM> remains a permanent part of the hub <NUM> after the over mold material <NUM> has been injected therein.

The front hub portion <NUM> can be over molded on the ferrule <NUM> or otherwise mounted on the ferrule <NUM>. Portions of the front hub portion <NUM> can interlock with corresponding slots or other openings in the side of the ferrule <NUM> to limit axial movement of the front hub portion <NUM> relative to the ferrule <NUM>. As shown at <FIG>, the front hub portion <NUM> includes a front end <NUM> and a rear end <NUM>. The rear end <NUM> is forwardly offset from a rear end <NUM> of the hub <NUM>. In this way, the rear end <NUM> of the hub <NUM> projects rearwardly from the rear end <NUM> of the front hub portion <NUM>. In certain examples, the front hub portion <NUM> is made of a harder, more rugged material than the over mold material <NUM>. In certain examples, the front hub portion <NUM> can be over molded on the ferrule <NUM> using a higher temperature and/or higher pressure molding process as compared to the molding process used to install the over mold material <NUM> in the outer hub shell <NUM>. Still referring to <FIG>, the front hub portion <NUM> can include a series of flats <NUM> used for indexing or otherwise rotationally positioning the ferrule assembly <NUM> in a connector such as the LC connector <NUM> of <FIG> and <FIG>. The front hub portion <NUM> can also include front chamfered sections <NUM> for seating the hub <NUM> within the connector <NUM>.

The front hub portion <NUM> can be over molded on the ferrule <NUM> prior to stripping, cleaning, cleaving, active alignment, and splicing operations. In this way, the front hub portion <NUM> can be used to facilitate handling of the ferrule assembly <NUM> during the various operations described above. During active alignment of the optical fiber stub <NUM> and the optical fiber <NUM>, the front end <NUM> of the front hub portion <NUM> can abut against a stop, side wall or other structure of the ferrule holder (e.g., see ferrule holder <NUM> of <FIG>) to ensure the ferrule <NUM> is positioned at a precise axial position relative to the ferrule holder. Thus, the front hub portion <NUM> can be used as a positive stop for controlling axial positioning of the ferrule <NUM> during the various operations described above.

In certain embodiments, the outer hub shell <NUM> abuts against the rear end of the front hub portion <NUM>. As shown at <FIG>, the outer hub shell <NUM> can include open regions <NUM> (internal cavities, internal slots, internal recesses, etc.) that axially overlap the rear end <NUM> of the ferrule <NUM> for allowing the over mold material <NUM> to fill this region and axially overlap the rear end <NUM> of the ferrule <NUM>. In certain examples, this type of configuration can provide better securement of the ferrule <NUM>. In certain examples, the outer hub shell <NUM> is a molded polymeric part such as an injection molded part. The outer hub shell <NUM> can be made of a material that is harder and more durable/robust than the over mold material <NUM> so as to reinforce the rear hub portion <NUM> and to protect and contain the over mold material <NUM>. In the case where the over mold material <NUM> is UV curable, the outer hub shell <NUM> can be manufactured of a material that is transmissive with respect to UV light such that the over mold material <NUM> can be cured by transmitting UV light/radiation through the outer hub shell <NUM>.

<FIG> show another ferrule assembly 20i and hub 230i in accordance with the principles of the present disclosure. The ferrule assembly 20i and hub 230i can have the same construction as the ferrule assembly <NUM> and hub <NUM> except the hub 230i includes an outer hub shell 900i having a male end <NUM> that fits within a female receptacle <NUM> defined at a back side of a front hub portion 502i. The male end <NUM> and the female receptacle <NUM> can have complementary shapes. As depicted, the male end <NUM> and the female receptacle <NUM> each include a series of flats that prevent relative rotation between the outer hub shell 900i and the front hub portion 502i. The male end <NUM> of the outer hub shell 900i is best shown at <FIG>.

<FIG> shows a further ferrule assembly 20j and hub 230j in accordance with the principles of the present disclosure. The ferrule assembly 20j and the hub 230j have the same basic configuration as the ferrule assembly <NUM> and hub <NUM> except the hub 230j includes an outer hub shell 900j having a two-piece construction. The two pieces of the outer hub shell 900j mate together with a splice location 218j captured thereinbetween to form the outer hub shell 900j.

<FIG> shows an alternative outer hub shell <NUM> that can be used with the ferrule assembly 20i and front hub portion 502i of <FIG>. The outer hub shell <NUM> includes two intermating half-pieces <NUM> that cooperate to define an internal chamber/cavity <NUM> for receiving overmold material. A port <NUM> for filling the chamber/cavity <NUM> with overmold material is defined by at least one of the half-pieces <NUM>. The half-pieces <NUM> cooperate to define a male end <NUM> at the front end of the outer hub shell <NUM>. Alignment features such as posts <NUM> and corresponding openings <NUM> ensure proper alignment between the half-pieces <NUM> of the outer hub shell <NUM> during assembly.

<FIG> and <FIG> show the connector <NUM> that includes the ferrule assembly <NUM> and the hub <NUM>. The connector <NUM> includes a main connector body <NUM> having a standard LC-style form factor and mechanical latching arrangement. The connector <NUM> also includes a spring <NUM> for biasing the ferrule assembly <NUM> and the hub <NUM> in a forward direction such that the chamfered section <NUM> of the hub <NUM> seats within the main connector body <NUM>. The connector <NUM> further includes a rear housing <NUM> that retains the spring within the main connector body <NUM>. The connector <NUM> further includes a crimp <NUM> for securing cable strength members to the rear housing <NUM>, and a boot <NUM> for providing strain relief and fiber bend radius control at the cable-to-connector interface.

While it is preferred for both the ferrule assembly manufacturing process and the fiber optic cable and connector manufacturing process to be fully automated, it will be appreciated that certain steps of either of the processes can be performed manually. Additionally, while it is preferred for the splicing technology and processing disclosed herein to be used in a factory setting, such technology and processing can also be used away from the factory in the field for field splicing applications (e.g., at a customer location). In other words, the fusion splice, splice protection, over molding, strength member fixation and assembly of the connector part or parts can be performed outside a factory, for example, at a customer site. Also, while the processing was described with respect to patch cords, it will be appreciated that the same processing technology can be used to attach a connector to any type of fiber optic cable of cord. Moreover, while SC connectors are shown, it will be appreciated that the technology is applicable to any type of fiber optic connector.

Another aspect of the present disclosure relates to a method for mass producing and distributing fiber optic connector assemblies. A significant aspect of the method relates to the centralized manufacturing of large quantities of ferrule assemblies each having a ferrule supporting a stub fiber. In certain examples, the volume of ferrule assemblies manufactured at a given centralized manufacturing location can exceed a volume of <NUM>,<NUM>; <NUM>,<NUM>,<NUM>; <NUM>,<NUM>,<NUM>; or <NUM>,<NUM>,<NUM> ferrule assemblies. By manufacturing such large volumes of ferrule assemblies at one centralized location, the ferrule assemblies can be made efficiently and considerable capital investment can be made in premium quality manufacturing equipment and processes. For example, the ferrule assemblies can be manufactured in a factory location using the highly precise polishing technology and equipment. Moreover, high quality and precisely toleranced ferrules and stub fibers can be effectively matched to provide the ferrule assemblies extremely high levels of optical performance. The large volumes of ferrule assemblies manufactured at a given centralized location provide the manufacturing efficiency for making this type of operation feasible. Examples of such high quality manufacturing operations and equipment are disclosed throughout the present disclosure. The centralized manufacturing also enables substantial investment in automation.

The method also relates to distributing ferrule assemblies manufactured at a centralized location to regional factories/mass production locations located closer to the intended point of sales. The relative small size of ferrule assemblies allows large volumes of such ferrule assemblies to be effectively shipped at relatively low costs. High costs associated with extensive shipment of cable can be significantly reduced. At the regional locations, connectorized fiber optic cable assemblies can be effectively and efficiently mass produced in a factory environment by splicing the ferrule assemblies to cables as described herein. The high level of precision provided in the ferrules, optical fibers, splicing techniques and manufacturing processes used at the central location effectively compensates for any losses associated with adding splices to the mass produced fiber optic connector assemblies. Once again, the high volumes of ferrule assemblies manufactured at the centralized locations provide the justification for making the capital expenditures necessary to provide the level of equipment quality, automation and manufacturing precision to make this manufacturing and distribution system feasible.

Aspects of the present disclosure allow ferrule assemblies to be manufactured in large volumes at manufacturing locations where process is most cost effective. The ferrule assemblies, which are small in size, can be efficiently shipped in bulk to factory/assembly locations closer to customer locations where the ferrule assemblies can be spliced to fiber optic cables and final connector assembly can take place. In this way, shipping of the cable itself (which tends to be larger in size and weight) can be minimized. Also, final assembly can be made closer to customer locations thereby decreasing lead times. Global supply chains can also be enhanced.

Claim 1:
A fiber optic assembly comprising:
a ferrule assembly (<NUM>) including a ferrule (<NUM>) and a fiber stub (<NUM>);
a fiber optic cable (<NUM>) including a cable fiber (<NUM>) that is fusion spliced to the fiber stub (<NUM>) at a splice location (<NUM>); and
a hub (<NUM>) mounted over a rear end of the ferrule (<NUM>) and also over the splice location (<NUM>), the hub (<NUM>) including a front hub portion (<NUM>) and a rear hub portion (<NUM>), the rear hub portion (<NUM>) including an outer hub shell (<NUM>) defining an interior chamber (<NUM>) that is occupied by a splice over mold material (<NUM>) that encapsulates the splice location (<NUM>);
wherein the outer hub shell (<NUM>) functions as a mold for shaping the over mold material (<NUM>) around the splice location (<NUM>) and along lengths of the cable fiber (<NUM>) and the fiber stub ( <NUM>), and wherein the outer hub shell (<NUM>) remains a permanent part of the hub (<NUM>) after the over mold material (<NUM>) has been injected therein,
characterized in that
the front hub portion (<NUM>) includes a series of flats (<NUM>) used for rotationally positioning the ferrule assembly (<NUM>) in a connector.