Patent ID: 12259584

DETAILED DESCRIPTION

Various embodiments will be further clarified by examples in the description below. In general, the description relates to a multi-fiber connector and fabrication method using a multi-fiber ferrule having a medial portion defining at least one array of grooves for receiving at least one array of optical fibers. In such a connector, each groove defined in the ferrule has a maximum depth greater than a diameter of an uncoated fiber segment to be received by the groove, and each groove is shaped and sized to permit a lower portion of a corresponding optical fiber to lack contact with the groove over large arc length of the optical fiber. Methods for fabricating a multi-fiber fiber optic connector including flexure of a medial portion of a groove-defining multi-fiber ferrule are also disclosed herein.

Before discussion formation of multi-fiber ferrules having arrays of grooves receiving optical fiber arrays and associated fabrication methods, conventional multi-fiber connectors and conventional V-groove arrays will be introduced.

One example of a conventional fiber optic connector10(also referred to as “optical connector10”, or simply “connector10”) is shown inFIG.1, with an exploded view of the connector being provided inFIG.2. The connector10is shown in the form of an MTP® connector, which is particular type of MPO connector (MTP® is a trademark of US Conec Ltd.).FIGS.1and2will be provided to facilitate discussion, as the multi-fiber ferrules and other components shown in subsequent figures (e.g., beginning withFIG.5A) may be used in connection with the same type of connector as the connector10. However, persons skilled in the field of optical connectivity will appreciate that the connector10is merely an example, and that the general principles disclosed with respect to the multi-fiber ferrules and other components shown in subsequent figures may also be applicable to other connector designs.

As shown inFIG.1, the connector10may be installed on a fiber optic cable12(“cable”) to form a fiber optic cable assembly14. The connector10includes a ferrule16, a housing18received over the ferrule16, a slider20received over the housing18, and a boot22received over the cable12. The ferrule16is spring-biased within the housing18so that a front portion24of the ferrule16extends beyond a front end26of the housing18. Optical fibers (not shown) carried by the cable12extend through bores28(also referred to as micro-holes) defined in the ferrule16before terminating at or near a front end face30of the ferrule16. The optical fibers are secured within the ferrule16using an adhesive material (e.g., epoxy) and can be presented for optical coupling with optical fibers of a mating component (e.g., another fiber optic connector; not shown) when the housing18is inserted into an adapter, receptacle, or the like.

As shown inFIG.2, the connector10also includes a ferrule boot32, guide pin assembly34, spring36, crimp body38, and crimp ring40. The ferrule boot32is received in a rear portion42of the ferrule16to help support the optical fibers extending to the ferrule bores28(shown inFIG.1). The guide pin assembly34includes a pair of guide pins44extending from a pin keeper46. Features on the pin keeper46cooperate with features on the guide pins44to retain portions of the guide pins44within the pin keeper46. When the connector10is assembled, the pin keeper46is positioned against a back surface of the ferrule16, and the guide pins44extend through pin holes48(shown inFIG.1) provided in the ferrule16so as to project beyond the front end face30of the ferrule16. Both the ferrule16and guide pin assembly34are biased to a forward position relative to the housing18by the spring36. The crimp body38is inserted into the housing18when the connector10is assembled and includes latching arms50that engage recesses52in the housing18. The spring36is compressed by this point and exerts a biasing force on the ferrule16via the pin keeper46. The rear portion42of the ferrule16defines a flange that interacts with a shoulder or stop formed within the housing18to retain the rear portion42of the ferrule16within the housing18. Aramid yarn or other strength members (not shown) from the cable12are positioned over an end portion54of the crimp body38that projects rearwardly from the housing18, and secured to the end portion54by the crimp ring40. The boot22covers this region, as shown inFIG.1, and provides strain relief for optical fibers emanating from the fiber optic cable12by limiting any extent to which the connector10can bend relative to the fiber optic cable12.

FIG.3is a cross-sectional view of an array of optical fibers65A-65C received in V-grooves64A-64C defined in an upper surface61of a conventional V-groove array member60and covered with a cover member70, to serve as a comparison structure for subsequently described embodiments. Each optical fiber65A-65C has a diameter that exceeds a height of the corresponding V-groove64A-64C. A dust particle68present in one (e.g., middle) V-groove causes the corresponding optical fiber65B to be elevated relative to (and therefore not perfectly collinear with) the other optical fibers65A,65C, as evidenced by the cover member70being arranged in contact with only the two optical fibers65A-65B, such that the cover member70is slightly non-parallel to the upper and lower surfaces61,62of the V-groove array member60. The combination of the optical fibers65A-65C, V-groove array member60, and cover member are in an (undesirable) overconstrained condition (referring to the multiple constraints acting on the same degree of freedom), whereby the presence of a dust particle68interferes with collinearity of the optical fibers65A-65C. This non-collinearity of the optical fibers65A-65C may lead to insertion loss if the V-groove array member60is to be coupled with another fiber array (not shown).

FIG.4Ais a front schematic view of an optical fiber85A received within a conventional V-groove having adjacent walls82A that are oriented about 90 degrees from one another. As shown, the optical fiber85A has a diameter that is greater than a height of the V-groove, measured as the distance between an upper surface81A and a trough84A thereof. The optical fiber85A contacts the walls82A at two locations86A, such that a non-contacting portion88A of an outer surface of the optical fiber85A spans an arc angle θ centered at a horizontal tangent T at a lowermost boundary89A of an outer surface of the optical fiber85A. As illustrated inFIG.4A, the angle θ is about 90 degrees.

FIG.4Bis a front schematic view of an optical fiber85B received within a conventional V-groove having adjacent walls82B that are oriented about 58 degrees from one another. As shown, the optical fiber85B has a diameter that is greater than a height of the V-groove, measured as the distance between an upper surface81B and a trough84B thereof. The optical fiber85B contacts the walls82B at two locations86B, such that a non-contacting portion88B of an outer surface of the optical fiber85B spans an arc angle θ centered at a horizontal tangent T at a lowermost boundary89B of an outer surface of the optical fiber85B. As illustrated inFIG.4B, the angle θ is about 116 degrees.

In both of the configurations shown inFIGS.4A-4B, presence of any contaminants in a V-groove has the potential to interfere with (e.g., vertical) positioning of optical fibers85A-85B relative to corresponding groove walls82A,82B.

Having described known connectors and V-groove devices for receiving optical fibers, embodiments of the present disclosure (e.g., including novel multi-fiber ferrule configurations and with optical fiber arrays, and associated methods) will now be described.

Various embodiments disclosed herein provide a multi-fiber connector that includes a multi-fiber ferrule defining an array of grooves in an upper surface of a medial portion, and an array of optical fibers with uncoated segments thereof received in the array of grooves. The optical fibers may be secured in the grooves with adhesive material (e.g., a UV-curable or multi-part adhesive material) and/or a groove covering block. Each groove has a maximum depth greater than (e.g., about 5% to 15% greater than) a diameter of an optical fiber segment to be received therein, and is shaped and sized to permit a lower portion of an optical fiber segment to lack contact with the groove over large arc length of the optical fiber when an upper surface of the medial portion defining the grooves facing upward. For example, a non-contacting portion of each optical fiber may comprise an arc of at least 120 degrees, at least 150 degrees, or another threshold angle disclosed herein, centered at lowermost boundary of the uncoated fiber segment. Each groove may be slightly tapered (e.g., with walls tapered 1 to 3 degrees from vertical, such that a groove is wider at an opening thereof, and narrower at a trough thereof), or untampered (with vertical walls providing a groove width that does not vary with respect to depth). In certain embodiments, an uncoated optical fiber segment may have a diameter of 125 μm, and a groove may have a depth in a range of 130 μm to 140 μm. Optical fiber segments may be introduced into grooves from the top, avoiding the difficulty associated with threading individual fibers into micro-holes, and more easily permitting optical fiber introduction to be automated. When optical fiber segments are received within grooves, fiber positioning is isostatic, and not hyperstatic (i.e., overconstrained) as in the case of conventional precision V-groove assemblies (such as shown inFIG.3).

In certain embodiments, a multi-fiber ferrule may be fabricated of aluminum, titanium, or zinc alloys, ceramic materials, or highly glass-filled polymers, by methods such as precision extrusion, injection molding, and/or electron discharge machining (EDM). In certain embodiments, grooves may be defined in an upper and/or a lower surface of a medial portion of a multi-fiber ferrule. In certain embodiments, grooves defined in a medial portion may have constant or substantially constant shape and dimensions (e.g., depth, wall angle, etc.) from a front to a rear (or proximal end to distal end) of the medial portion (e.g., as shown inFIGS.18A-18B, described hereinafter). In certain embodiments, grooves defined in a front or proximal section of a medial portion may have one dimension to receive uncoated optical fiber segments while groove extensions defined in a rear or distal section of the medial portion may have different shapes and/or dimensions (e.g., depth, wall angle, etc.) to receive coated optical fiber segments (e.g., as shown inFIGS.5A and6, described hereinafter), wherein such an arrangement may be produced by techniques such as injection molding, or by extrusion followed by machining (or another material removal process).

In certain embodiments, a multi-fiber ferrule may resemble a H-shape, with a thin medial portion arranged between increased thickness lateral portions. In certain embodiments, each lateral portion may comprise a thickness in a range of 2 mm to 2.7 mm, or about 2.2 to about 2.6 mm, or about 2.4 mm, and the medial portion may have a thickness in a range of from about 0.3 mm to about 0.7 mm, or about 0.5 to about 0.65 mm, or about 0.6 mm. A thickness of a medial portion of a multi-fiber ferrule may take into account material properties of the material of the ferrule to permit the medial portion to be flexed into a configuration in which at least the top surface of the medial portion is non-linear (e.g., curved) in shape to thereby expand an average width of at least some of the grooves to ease the insertion of uncoated optical fiber segments (not shown) into the grooves.

In certain embodiments, a medial portion of a multi-fiber ferrule may be flexed such that an upper surface thereof assumes a non-linear (e.g., curved) configuration, to expand an average width of at least some grooves of the array of grooves defined in the medial portion in order to allow easy insertion of multiple optical fibers at a time into the array of grooves (i.e., with each groove receiving one optical fiber). Following insertion, the medial portion of the multi-fiber ferrule may be flexed (or a bending force may be released) back to its straight position, causing an average width of each groove to return to an unexpanded state, thereby promoting self-gripping of optical fibers within the grooves. In certain embodiments, a medial portion of the multi-fiber ferrule is initially subjected to elastic flexure, whereby upon release of a bending moment, an upper portion of the medial portion will return to a flat configuration of its own accord, without requiring imposition of a counteracting bending moment. Alternatively, initial flexure may result in non-elastic deformation. In certain embodiments, a bending moment of a first orientation may be applied to a medial portion of a multi-fiber ferrule to cause the medial portion to flex in one direction, and a thereafter a bending moment of an opposing second orientation may be applied to the medial portion in order the cause the medial portion to flex in a direction opposing the one direction. Dimensions of the grooves and the material of the ferrule may be selected to ensure a desirable range of lateral gripping force without risking breakage of optical fibers or silica cladding portions thereof.

After optical fiber segments are received in grooves of a multi-fiber ferrule that are deeper than a diameter of each optical fiber segment, the optical fiber segments may be moved (e.g., pressed as a group using an external push bar, roller, or other mechanism) in a direction away from troughs of the grooves toward a reference block positioned in contact with a medial portion of the ferrule, to linearly arrange optical fiber segments while being separated from the trough of each groove. Positioning of optical fiber segments within grooves of ferrule may be ensured independently in both a horizontal and vertical direction. In certain embodiments, optical fibers may be secured in grooves with adhesive material, such as a bi-component adhesive or UV-curable adhesive. In certain embodiments, a reference block may be removed from a ferrule after the optical fibers are secured in position. In certain embodiments, a reference block may be embodied in a groove covering block that is part of a final assembly, remaining positioned against a portion of a multi-fiber ferrule in a resulting multi-fiber connector. In certain embodiments, a reference block may comprise a precision glass plate that is secured in place with a compressive metallic clip and/or with adhesive material. In certain embodiments, a reference block may comprise an extruded or injection molded body produced in manner similar to a multi-fiber ferrule. Optionally, a reference block may be configured to be mechanically retained by one or more features (e.g., protrusions or recesses arranged at side surfaces of lateral portions) of a multi-fiber ferrule.

In certain embodiments, a multi-ferrule may include apertures or recesses that are defined in lateral portions and are configured to receive alignment pins (e.g., 0.7 mm diameter precision pins44as shown inFIG.2). In certain embodiments, a central axis of each alignment pins when received by a multi-fiber ferrule may be arranged coplanar with an array of optical fibers received in grooves of the ferrule. In certain embodiments, a plane containing the central axis of each alignment bore and/or alignment pin when received by a multi-fiber ferrule may be arranged with a desired offset to the plane of the array of optical fibers received in grooves of the multi-fiber ferrule.

FIG.5Ais a perspective view, andFIG.5Bis a front elevational view, of a multi-fiber ferrule90that is useable as part of a multi-fiber connector according to one embodiment. The multi-fiber ferrule90includes a medial portion91arranged between lateral portions104A-104B of greater thickness than to the medial portion91. The medial portion91includes an upper surface94and an opposing lower surface92, wherein an array of grooves100A-100L and an array of groove extensions102A-102L are defined in the medial portion91and recessed relative to the upper surface94. An upper boundary of each groove100A-100L extends to the upper surface94, while an upper boundary of each groove extension102A-102L terminates is at a level lower than the upper surface94. Each groove extension102A-102L is registered (i.e., aligned) with a corresponding groove100A-100L, with each groove extension102A-102L being configured to receive a coated optical fiber segment (e.g., as shown inFIG.6), and each groove100A-100L being configured to receive an uncoated optical fiber segment (e.g., as shown inFIG.6). Each lateral portion104A-104B has a thickness substantially greater than that of the medial portion91, with the medial portion91being arranged at a level approximately midway between upper surfaces106A-106B and lower surfaces108A-108B of the lateral portions104A-104B, such that the multi-fiber ferrule90comprises a widened “H”-shape. Each lateral portion104A-104B defines an aperture107A-107B extending horizontally therethrough in a direction parallel to the grooves100A-100L. These apertures107A-107B are sized and shaped to receive alignment pins (e.g.,109A-109B as shown inFIG.6), wherein upon insertion, a centerline of the alignment pins may be arranged coplanar with an array of optical fibers (e.g.,110as shown inFIG.6). As shown, a recess109is provided above the upper surface94and between the lateral portions104A,104B. In certain embodiment, a reference block (not shown) may be positioned in the recess109to assist with optical fiber positioning and/or retention after optical fiber segments are received by the grooves100A-100L.

In certain embodiments, a centerline of the alignment pins (e.g.,109A-109B as shown inFIG.6) associated with the multi-fiber ferrule90may be offset from a centerline of an optical fiber array received by the grooves100A-100L. When two multi-fiber ferrules are first mated in contact with one another, tips of optical fibers supported by the ferrules may slide slightly on a plane of contact (e.g., because of spring force applied to the ferrules) until the pins and ferrules resist that sliding by deforming slightly. This deformation may be accommodated by a slight offset between a centerline of alignment pins associated with the ferrules, and a centerline of optical fiber arrays associated with the ferrules. In this regard, a plane containing a central axis of alignment bores of a multi-fiber ferrule may be arranged with a desired offset relative to a plane of an array of optical fibers received in grooves of the multi-fiber ferrule.

FIG.6is a perspective view of the multi-fiber ferrule90ofFIGS.5A-5B, showing alignment pins109A-109B received within the apertures (107A-107B inFIGS.5A-5B) defined in the lateral portions104A-104B, and showing an array of optical fibers110positioned above the array of grooves100A-100L and the array of groove extensions102A-102L defined in the medial portion91. As shown, the array of optical fibers110includes twelve optical fibers110A-110L arranged in a one-dimensional array, wherein each optical fiber110A-110L includes a coated fiber segment114A-114L and an uncoated (e.g., stripped) fiber segment112A-112L. Each groove100A-100L is configured to receive an uncoated fiber segment112A-112L, and each groove extension102A-102L is configured to receive a length of a coated fiber segment114A-114L. Although the grooves100A-100L, groove extensions102A-102L, and optical fibers110A-110L are each provided as twelve in number, any suitable number of these elements (e.g., 8, 12, 24, or some other number) may be provided. In certain embodiments, after the optical fibers110A-110L are received by the multi-fiber ferrule90, the end of each uncoated segment112A-112L may be cleaved and/or polished flush with a terminus of a corresponding groove100A-100L.

As noted previously, the medial portion of a multi-fiber ferrule may be flexed such that an upper surface thereof assumes a non-linear (e.g., curved) configuration, to expand an average width of at least some grooves of the array of grooves defined in the medial portion in order to allow easy insertion of multiple optical fibers at a time into the array of grooves.

FIG.7Ais a front cross-sectional view of the medial portion91of the multi-fiber ferrule ofFIGS.5A-5B and6arranged in a non-linear (curved) configuration over a centrally located external shim99, with the array of optical fibers110(specifically including uncoated fiber segments112A-112L) disposed above the array of grooves100A-100L. Each groove100A-100L is roughly U-shaped and is recessed relative to the upper surface94, which opposes the lower surface92that contacts the shim99. In certain embodiments, each groove100A-100L is configured to receive a 125 micron diameter uncoated optical fiber segment112A-112L. When the medial portion91is flexed downward (e.g., by pressing downward along left and right ends of the medial portion91with the shim99positioned in contact with a center of the lower surface92, ends of the medial portion91may be deflected by a nonzero angle (e.g., two to six degrees, or three to five degrees, or about a five degree angle from vertical) when the shim99has a thickness of 150 microns, and in such a configuration the medial portion91forms a shallow arch that causes an upper portion of each groove100A-100L to be expanded in width (e.g., by 3 to 5 microns), thereby easing insertion of the uncoated fiber segments112A-112L into the grooves100A-100L by relative movement therebetween (e.g., by downward motion of the uncoated fiber segments112A-112L and/or upward motion of the medial portion91).

FIG.7Bshows the medial portion91ofFIG.7Aremaining in an upwardly-flexed configuration, but with the uncoated fiber segments112A-112L received within the grooves100A-100L. As shown, the upper and lower surfaces94,92of the medial portion91remain flexed into non-linear (e.g., curved) shapes, wherein a leftmost boundary of the lower surface92is deflected by an angle β (e.g., in a range of 1-5 degrees, or about 2-4 degrees, or about 3 degrees) relative to horizontal. In certain embodiments, when the medial portion91is flexed and an upper portion of each groove100A-100L is expanded in width, a small clearance (e.g., 3 to 5 microns) between each uncoated fiber segment112A-112L and a corresponding groove100A-100L may be established, to beneficially accommodate passage of adhesive (not shown) that may surround each uncoated fiber segment112A-112L in the grooves100A-100L and/or permit free motion of each uncoated fiber segment112A-112L within the grooves100A-100L when the optical fibers are pressed upward (e.g., by an external push bar, roller, or other mechanism, as shown inFIGS.11A-12).

Magnified cross-sectional views of optical fibers are provided inFIGS.8A to9, and are discussed below.

FIG.8Ais a simplified front cross-sectional view of an uncoated optical fiber segment112received within, and arranged proximate to a height midpoint of, a groove100of the multi-fiber ferrule ofFIG.6. As shown, the groove100has a U-shape, and the optical fiber segment112has a diameter that is smaller than a height of the groove100, measured as the distance between an upper surface94and a trough100-3of the groove100. The uncoated optical fiber segment112contacts walls100-1of the groove100at two locations116, such that a non-contacting portion118of an outer surface of the uncoated optical fiber segment112spans an arc angle θ centered at a horizontal tangent T at a lowermost boundary119of an outer surface of the optical fiber segment112. As illustrated inFIG.8A, the angle θ is in a range of more than about 175 degrees (or in a range of 175 to 180 degrees, or a range of 176 to 179 degrees).

FIG.8Bis a simplified front cross-sectional view of the groove100and uncoated optical fiber segment112ofFIG.8A, following movement of the optical fiber segment112within the groove100(e.g., upward, in a direction away from the groove trough100-3as indicated by arrow A) to contact a reference block120positioned against an upper surface94(of the medial portion91of the ferrule90, showing inFIGS.4A-4B) bounding the groove100. Such movement of the uncoated optical fiber segment112may be caused by pressing multiple optical fibers segments upward using a push bar, roller, or other structure (to be described hereinafter in connection withFIGS.11A-12). In certain embodiments, the uncoated optical fiber segment112may have a diameter of 125 μm, and the groove100may have a depth in a range of 130 μm to 140 μm. In certain embodiments, the groove100may have a smaller depth (e.g., in a range of 50 μm to 125 μm, or in a range of 75 μm to 120 μm) to accommodate reduced clad optical fiber with outer diameter values smaller than 125 μm. In certain embodiments, grooves100may have a center-to-center pitch in a range of 150 μm to 250 μm

FIG.9is a simplified front cross-sectional view of an alternative groove, composed of differently-tapered upper and lower wall portions100-1′,100-2′ that provide an angled (instead of curved) trough100-3′, with an uncoated optical fiber segment112received therein according to an embodiment of the disclosure. As shown, the optical fiber segment112has a diameter that is smaller than a height of the groove formed by the differently-tapered wall portions100-1′,100-2′, measured as the distance between an upper surface94′ and a trough100-3′ of the groove. The uncoated optical fiber segment112contacts upper wall portions100-1′ at two locations116′, such that a non-contacting portion118′ of an outer surface of the uncoated optical fiber segment112spans an arc angle θ centered at a horizontal tangent T at a lowermost boundary119′ of an outer surface of the optical fiber segment112. As illustrated inFIG.9, the angle θ is in a range of more than about 165 degrees.

FIG.10is a front cross-sectional view of a wedge-shaped portion of an optical fiber segment112″ having an arc118″ along a lower edge thereof that corresponding to a non-contacting portion of the optical fiber when received within a groove of a multi-fiber ferrule as disclosed herein. The arc118″ is centered at a lowermost boundary119″ of an outer surface of the optical fiber segment, and extends below and between two points of contact116″ with a ferrule groove (not shown), such that the arc118″ spans an arc angle θ″ centered at a horizontal tangent T at a lowermost boundary119′ of an outer surface of the optical fiber segment112″. As illustrated inFIG.10, the angle θ is in a range of more than about 130 degrees.

FIG.11Ais a front cross-sectional view of a medial portion191of a multi-fiber ferrule190with an array of optical fiber segments112A-112L positioned proximate to height midpoints of grooves200A-300L defined in the medial portion191of the ferrule190, with a translatable element224such as a push bar224(connected to support226) positioned below the optical fiber segments112A-112L, and with a reference block220positioned above the optical fiber segments112A-112L. Optionally, the translatable element224may be embodied in a rollable element such as rotatable cylinder to reduce friction upon contact with the optical fiber segments112A-112L. Both the translatable element224and the reference block220are positioned in a non-contacting relationship with the optical fiber segments112A-112L, in preparation for movement of the translatable element224upward to press the optical fiber segments112A-112L (which extend beyond the ferrule190) upward to contact the reference block220.FIG.11Bis a front cross-sectional view of the items ofFIG.11A, following movement of the translatable element224to push the optical fibers segments112A-112L upward within the array of grooves200A-200L (i.e., away from troughs of the grooves200A-200L) to contact a lower surface221of the reference block220. In certain embodiments, adhesive material (not shown) may be provided in the grooves200A-200L around the uncoated optical fiber segments112A-112L to secure them in place if or when the reference block220is removed. Although the optical fiber segments112A-112L are moved as a group by the reference block220, each individual optical fiber segments112A-112L is positioned independently relative to the others within a corresponding groove200A-200L, providing isostatic positioning utility. Such system is more accommodating of the presence of dust or debris than prior art systems, such as the overconstrained V-groove array ofFIG.3.

FIG.12is a side cross-sectional view an uncoated optical fiber segment112A, medial portion191of ferrule190, translatable element224, and reference block220positioned as inFIG.11B, with the optical fiber segment112A contacting the translatable element224and the reference block220. As shown, the optical fiber segment112A extends beyond the ferrule190to permit the optical fiber segment112A to be pressed directly between the translatable element224and the lower surface221of the reference block220.FIG.12further shows a coated optical fiber segment114A extending from the uncoated optical fiber segment112A, with a portion thereof also supported by the ferrule190.

FIG.13is a front cross-sectional view of the medial portion191, uncoated optical fiber segments112A-112L, and reference block220positioned above and against the medial portion191as shown inFIG.11B, following removal of the translatable element (224inFIG.11B). With As shown, the uncoated optical fiber segments112A-112L are positioned at (or near) the top of corresponding grooves200A-200L proximate to the lower surface221of the reference block220, wherein the uncoated optical fiber segments112A-112L may be secured in such position with adhesive material (not shown) in the grooves200A-200L. In certain embodiments, a horizontal tangent of an uppermost boundary of each uncoated optical fiber segment112A-112L is substantially registered with the upper surface194of the medial portion191. Although only a medial portion191of a multi-fiber ferrule190is shown, it is to be recognized that in practice, the ferrule190may additionally include increased thickness lateral portions (e.g.,104A,104B as shown inFIG.6).

Various mechanisms may be used to flex a medial portion of a multi-fiber ferrule into a non-linear (e.g., curved) configuration. As noted previously herein, a shim may be arranged below a center of a medial portion of a multi-fiber ferrule, and the medial portion pressed downward along edges thereof to promote flexure. In certain embodiments, lateral portions of a multi-fiber ferrule may be positioned between vertical restraints, and a first plunger (e.g., a hydraulically or mechanically actuated plunger) may be used to press a center of a medial ferrule portion upward into a non-linear configuration to facilitate loading of optical fiber segments into grooves of the ferrule. If desired, a second plunger may subsequently be used to press a reference block downward against the medial portion of the ferrule, to promote downward flexure of the medial portion and/or permit optical fiber segments to be arranged at appropriate positions within the grooves of the ferrule.

FIG.14Ais a front cross-sectional view of an array of uncoated optical fiber segments112A-112L received within array of grooves300A-300L that are recessed relative to an upper surface294of a medial portion291of a multi-fiber ferrule290. Thicker lateral portions304A-304B of the multi-fiber ferrule290have upper surfaces306A-306B and lower surfaces308A-308B that are positioned between vertical restraints311-312that are part of a static fixture. The lateral portions304A-304B of the ferrule290also define recesses307A,307B for receiving alignment pins (not shown). A cavity309is provided above the upper surface294and between the lateral portions304A,304B. As shown, a lower plunger315is positioned below a center of the medial portion291to push the medial portion291upward to flex the upper surface294into a non-linear (curved) configuration, thereby expanding at least upper portions of the grooves300A-300L to ease loading of the optical fiber segments112A-112L therein.

FIG.14Bshows the items ofFIG.14A, with addition of an upper plunger316to press a reference block320into the cavity309to cause a lower surface321thereof to contact the upper surface294of the medial portion291and contact optical fibers112A-112L arranged in the grooves300A-300L. The remaining elements ofFIG.14Bare identical to those described in connection withFIG.14A. Optionally, the reference block320may comprise or be embodied in a groove covering block that is part of a final assembly, remaining positioned against the medial portion291of the multi-fiber ferrule290, and may be retained in position using adhesive (not shown) arranged in the cavity309proximate to the reference block320. The upper plunger316may be used to push the reference block320and the medial portion291downward to cause an upper surface294of the medial portion291to assume a linear (non-curved) configuration.FIG.14Cis a front cross-sectional view of the optical fiber segments300A-300L, multi-fiber ferrule290, and reference block320ofFIG.14B, following removal of the ferrule290from a fixture including the support surfaces and plungers ofFIG.14C. The remaining elements ofFIG.14Care the same as described above in connection withFIGS.14A-14B.

In certain embodiments, a medial portion of a multi-fiber ferrule may have a non-constant thickness, such as a thickness that is greatest at a center thereof (equally distanced between lateral portions of the ferrule). Such a configuration may assist in producing an arc-like or other desired shape along an upper surface of the medial portion of a ferrule when such medial portion is flexed upward to receive optical fiber segments in grooves thereof.

FIG.15Ais a simplified front cross-sectional view of a multi-fiber ferrule390having a medial portion391of a non-constant thickness (being thickest at a center thereof) positioned between thicker lateral portions404A-404B that define recesses407A-407B for receiving alignment pins (not shown). Although no grooves are illustrated in the medial portion391, it is to be appreciated that an operative ferrule390would include an array of grooves defined in an upper surface394of the medial portion391such as shown in previous embodiments herein. As shown, the upper surface394of the medial portion391is in a linear (flat) configuration, and the lower surface392of the medial portion391is in a non-linear (curved) configuration, when the medial portion391is in a non-flexed state. A shim415is positioned below a center of the lower surface392in preparation for deflecting the medial portion391upward.FIG.15Bshows the same ferrule390and shim415as depicted inFIG.15A, but with the medial portion391pressed upward by the shim415to flex the upper surface394into a non-linear (e.g., curved) configuration resembling a shallow circular arc (wherein in certain embodiments the lower surface392can also be flexed into a linear configuration). Such configuration of the upper surface394may allow optical fiber segments to be loaded into grooves, assuming grooves (not shown) are arranged in the upper surface394.

Various methods for producing a multi-fiber ferrule have been described previously herein. In certain embodiments, a multi-fiber ferrule may be produced by extrusion using an extrusion die.FIG.16is a cross-sectional view of an extrusion die420for producing a multi-fiber ferrule of a connector according to one embodiment of the present disclosure. The extrusion die420defines a cavity430having a medial cavity portion431and a groove-defining upper surface435for producing a medial portion of a ferrule, with the cavity further including thicker lateral cavity portions434A-434B for producing lateral portions of a ferrule.

Although various embodiments disclosed herein have included ferrules suitable for receiving twelve optical fiber segments, it is to be appreciated that a multi-fiber ferrule may define any suitable number of grooves (e.g., 8, 12, 24, or some other number) for receiving a like number of optical fiber segments.FIG.17is a perspective view of an array of twenty-four optical fiber segments112A-112X arranged within an array of grooves500A-500X defined in an upper surface494of a medial portion491of a multi-fiber ferrule490useable in a connector according to one embodiment. The medial portion491is arranged between increased thickness lateral portions504A-504B each having a corresponding alignment pin509A-509B extending therethrough, with the alignment pins509A-509B being arranged substantially coplanar with the array of optical fibers112A-112X. The lateral portions504A-504B extend between upper surfaces506A-506B and lower surfaces508A-508B that are non-coplanar with the medial portion491. A reference block520is positioned in a recess above the medial portion491and between the lateral portions504A-504B of the multi-fiber ferrule490, with a lower surface521of the reference block520arranged in contact with the upper surface494of the medial portion491as well as the optical fiber segments112A-112X received in the grooves500A-500X. In certain embodiments, an upper surface522of the reference block520may be arranged substantially coplanar with the upper surfaces506A-506B of the lateral portions504A-504B of the multi-fiber ferrule490, to permit the multi-fiber ferrule490to be used as part of an otherwise known connector assembly (e.g., in the connector10shown inFIG.1). In certain embodiments, a multi-fiber ferrule of one connector may be arranged to couple optical fiber segments with corresponding optical fiber segments supported by a multi-fiber ferrule of another connector.

FIG.18Ais a perspective view of a first multi-fiber ferrule590useable in a connector according to one embodiment of the present disclosure, with alignment pins609A-609B (each having an associated pin keeper610A-610B) extending through apertures defined in lateral portions604A-604B of the first multi-fiber ferrule590. A medial portion591of the first multi-fiber ferrule590is positioned between the lateral portions604A-604B and define an array of grooves in an upper surface592of the medial portion591for receiving a first array of optical fiber segments (not shown), with the grooves extending continuously from a front (or proximal) end601to a rear (or distal) end602of the first multi-fiber ferrule590.FIG.18Bis a perspective view of the first multi-fiber ferrule590and alignment pins609A-690B ofFIG.18A, with the alignment pins609A-609B further extending through apertures defined through lateral portions604A′-604B′ of a second multiple-fiber ferrule590′ that includes a medial portion591′ defining an array of grooves in an upper surface592′ (extending from a front end601′ to a rear end602′) for supporting a second array of optical fiber segments (not shown).FIG.18Bshows the ferrules590,590′ arranged in a “key-up to key-up” configuration, so that a light signal from one numbered optical fiber (e.g., a first optical fiber) associated with the first multi-fiber ferrule590is transmitted to a differently numbered optical fiber (e.g., a twelfth optical fiber) associated with the second multi-fiber ferrule590′. In certain embodiments, the ferrules590′,590′ may be arranged in a “key-up to key-down” configuration so that light from a first numbered optical fiber associated with the first multi-fiber ferrule590is transmitted to a correspondingly numbered optical fiber associated with the second multi-fiber ferrule590′. In certain embodiments, the front or proximal ends601,601′ of the multi-fiber ferrules590,590′ may be arranged perpendicular to the upper surfaces592,592′. In certain embodiments, the front or proximal ends601,601′ of the multi-fiber ferrules590,590′ may be non-perpendicular to the upper surfaces592,592′, such as at an angle of 8 to 9 degrees away from perpendicular to the upper surfaces592,592′ to permit optical fibers associated with the multi-fiber ferrules590,590′ to be polished to the same angle at the front or proximal ends601,601′ of the multi-fiber ferrules590,590′ in order to reduce back-reflection of optical signals between mated optical fiber ends. In certain embodiments, the front or proximal ends601,601′ of the multi-fiber ferrules590,590′ may be non-perpendicular to the upper surfaces592,592′ at the same or complementary angles to permit the multi-fiber ferrules590,590′ to be arranged in a key-up to key-down configuration, or alternatively in a key-up to key-up configuration.

FIG.19is a perspective view of the first multi-fiber ferrule and alignment pins ofFIG.18A, showing grooves600A-600L of the medial portion591having received therein uncoated optical fiber segments112A-112L that extend from corresponding coated optical fiber segments114A-114B of an optical fiber array110. The optical fiber array110extends generally between the alignment pin keepers610A-610B associated with alignment pins that may be used as retaining and alignment structures within and between multi-fiber connectors.

In certain embodiments, a medial portion of a multi-fiber ferrule may first and second parallel rows of grooves for receiving first and second arrays of optical fibers, resulting in a two-dimensional array. For example, in certain embodiments, a medial portion of a multi-fiber ferrule may include an upper surface defining a first array of grooves for receiving a first array of optical fibers, and may include a lower surface defining a second array of grooves for receiving a second array of optical fibers. The respective arrays of optical fibers may be retained in the corresponding arrays of grooves with an adhesive material and/or first and second reference blocks, optionally embodied in a groove covering blocks that are part of a final assembly, remaining positioned against portions of the multi-fiber ferrule as part of a multi-fiber connector.

FIG.20is a front cross-sectional view of a multi-fiber ferrule690including a medial portion691having a first array of grooves700A-700L defined in an upper surface694of the medial portion691, and having a second array of grooves701A-701L defined in a lower surface695of the medial portion691. The medial portion691is arranged between thicker lateral portions704A-704B, which have upper surfaces706A,706B and lower surfaces708A,708B, and which define recesses707A,707B for receiving alignment pins (not shown). An upper cavity709is provided above the upper surface694and between the thicker lateral portions704A-704B, and a lower cavity710is provided below the lower surface695and between the thicker lateral portions704A-704B. A first array of optical fibers112A-112L is received in the first array of grooves700A-700L and positioned against a lower surface721of a first reference block720arranged in the upper cavity709, and a second array of optical fibers113A-113L is received in the second array of grooves701A-701L and positioned against an upper surface731of a second reference block730arranged in the lower cavity710. In certain embodiments, the arrays of optical fibers112A-112L,113A-113L may have the same pitch and spacing as optical fibers of a conventional MPO connector.

In certain embodiments, a multi-fiber connector comprises a first array of optical fibers each having a first uncoated segment that has a first diameter and that has a first outer surface, a second array of optical fibers each having a second uncoated segment that has a second diameter and that has a second outer surface, and a multi-fiber ferrule defining a first array of grooves that are recessed relative to an upper surface of a medial portion of the multi-fiber ferrule and defining a second array of grooves that are recessed relative to a lower surface of the medial portion. Each groove of the first array of grooves has a first maximum depth that is greater than the first diameter, and each groove of the second array of grooves has a second maximum depth that is greater than the second diameter. Each optical fiber of the first array of optical fibers comprises a non-contacting portion of the first outer surface that is devoid of contact with the first array of grooves, and the non-contacting portion comprises an arc of at least 120 degrees and that is centered at a horizontal tangent of a lowermost boundary of the first outer surface. Likewise, each optical fiber of the second array of optical fibers comprises a non-contacting portion of the second outer surface that is devoid of contact with the second array of grooves, and the non-contacting portion comprises an arc of at least 120 degrees and that is centered at a horizontal tangent of an uppermost boundary of the second outer surface.

In certain embodiments, an array of optical fibers (optionally provided in a ribbon) may be prepared for inclusion in a connector by stripping ends of the optical fibers to produce uncoated fiber segments, with unstripped portions of the same optical fibers embodying coated fiber segments that embody continuous extensions of the uncoated fiber segments. The uncoated fiber ends may then be cleaned according to conventional cleaning steps. A medial portion of a multi-fiber ferrule as disclosed herein may flexed into a non-linear configuration, thereby expanding an average width of at least some grooves defined therein, and the uncoated fiber segments may be inserted into the grooves. Ends of the uncoated fiber segments may extend beyond the grooves. Optionally, adhesive material may be provided in the grooves and/or around an exterior of the uncoated fiber segments when the uncoated fiber segments are inserted into the grooves. After insertion of the uncoated fiber segments into the grooves, a reference block is positioned proximate to a surface of the medial portion defining the grooves, and the uncoated fiber ends are pressed away from troughs of the grooves (e.g., in an upward direction) to contact a surface of the reference block. The medial portion of the reference block may then be unflexed (or flexed in a direction opposing the initial flexure) to cause substantially the entire medial portion of the ferrule to contact a surface of the reference block, so that the uncoated fiber segments are linearly aligned by contact with the surface of the reference block. If the reference block is to be maintained as part of a final assembled connector, the reference block may be retained in or against the ferrule with an adhesive material and/or a securing clip. End portions of the uncoated fiber segments extending beyond the medial portion of the multi-fiber ferrule may be cleaved and polished flush with a surface of the multi-fiber ferrule. Thereafter, the multi-fiber ferrule with arrayed optical fibers retained therein may be incorporated into a multi-fiber connector, such as (but not limited to) the type shown inFIGS.1-2.

In certain embodiments, the steps of flexing a medial portion of a multi-fiber ferrule into a non-planar configuration, and returning the medial portion of a ferrule to a planar configuration, may be omitted when grooves defined in the ferrule have appropriately tapered walls.

Those skilled in the art will appreciate that other modifications and variations can be made without departing from the spirit or scope of the invention. Since modifications, combinations, sub-combinations, and variations of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and their equivalents. The claims as set forth below are incorporated into and constitute part of this detailed description.

It will also be apparent to those skilled in the art that unless otherwise expressly stated, it is in no way intended that any method in this disclosure be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim below does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred. Moreover, where a method claim below does not explicitly recite a step mentioned in the description above, it should not be assumed that the step is required by the claim.