Patent Publication Number: US-2021173150-A1

Title: Fiber optic connector

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/696,629, filed Nov. 26, 2019; which is a continuation of U.S. patent application Ser. No. 16/204,672, filed Nov. 29, 2018, now U.S. Pat. No. 10,495,822; which is a continuation of U.S. patent application Ser. No. 15/837,290, filed Dec. 11, 2017, now U.S. Pat. No. 10,146,011; which is a continuation of U.S. patent application Ser. No. 15/357,030, filed Nov. 21, 2016, now U.S. Pat. No. 9,841,566; which is a continuation of U.S. patent application Ser. No. 14/858,900, filed Sep. 18, 2015, now U.S. Pat. No. 9,500,813; which is a continuation of U.S. patent application Ser. No. 14/154,352, filed Jan. 14, 2014, now U.S. Pat. No. 9,151,904; which is a continuation of U.S. patent application Ser. No. 13/420,286, filed Mar. 14, 2012, now U.S. Pat. No. 8,636,425, which claims the benefit of U.S. Provisional Patent Application Ser. Nos. 61/510,711, filed Jul. 22, 2011; and 61/452,953, filed Mar. 15, 2011, which applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to optical fiber communication systems. More particularly, the present disclosure relates to fiber optic connectors used in optical fiber communication systems. 
     BACKGROUND 
     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 without requiring a splice. Fiber optic connectors can be used to optically interconnect two lengths of optical fiber. Fiber optic connectors can also be used to interconnect lengths of optical fiber to passive and active equipment. 
     A typical fiber optic connector includes a ferrule assembly supported at a distal end of a connector housing. A spring is used to bias the ferrule assembly in a distal 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 distal end face at which a polished end of the optical fiber is located. When two fiber optic connectors are interconnected, the distal end faces of the ferrules abut one another and the ferrules are forced proximally relative to their respective connector housings against the bias 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 an intermediate fiber optic adapter. 
     A fiber optic connector is often secured to the end of a corresponding fiber optic cable by anchoring strength numbers 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 strength numbers 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. 
     As indicated above, when two fiber optic connectors are interconnected together, the ferrules of the two connectors contact one another and are respectively forced in proximal directions relative to their housings against the bias of their respective connector springs. In the case of pull-proof connectors, such proximal movement of the ferrules causes the optical fibers secured to the ferrules to move proximally relative to the connector housings and relative to the jackets of the fiber optic cables secured to the connectors. To accommodate this relative proximal movement of the optical fibers, the fiber optic cables typically have sufficient interior space to allow the optical fibers to bend in a manner that does not compromise signal quality in a meaningful way. Typically, the bending comprises “macrobending” in which the bends have radii of curvatures that are larger than the minimum bend radius requirements of the optical fiber. 
     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 the ability to provide enhanced connector/circuit densities. Still another aspect relates to the ability to provide high signal quality connections with minimal signal degradation. 
     SUMMARY 
     One aspect of the present disclosure relates to a fiber optic connector having features that facilitate connector assembly. For example, such features can include structures for enhancing guiding optical fibers into a connector during assembly, and for facilitating applying epoxy into a ferrule of a connector during assembly. 
     Another aspect of the present disclosure relates to fiber optic connectors having features that prevent unacceptable bending of an optical fiber when ferrules of the connectors are moved proximally relative to the connector housings as two connectors are coupled together. In certain embodiments, the connectors can include space for accommodating macrobending of the optical fibers within the connector housings. 
     A variety of additional aspects will be set forth in the description that follows. The aspects relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective, exploded view of a fiber optic connector in accordance with the principles of the present disclosure; 
         FIG. 2  is a cross-sectional view that longitudinally bisects the fiber optic connector of  FIG. 1 ; 
         FIG. 3  is a perspective view of a rear housing of the fiber optic connector of  FIG. 1 ; 
         FIG. 4  is a cross-sectional view that longitudinally bisects the rear housing of  FIG. 3 ; 
         FIG. 5  is a perspective view showing a first end of a first insertion cap that can be used with the fiber optic connector of  FIG. 1 ; 
         FIG. 6  is a perspective view showing a second end of the insertion cap of  FIG. 5 ; 
         FIG. 7  is a cross-sectional view that longitudinally bisects the insertion cap of  FIGS. 5 and 6 . 
         FIG. 8  is a perspective view showing a first end of a second insertion cap that can be used with the fiber optic connector of  FIG. 1 ; 
         FIG. 9  is a perspective view showing a second end of the insertion cap of  FIG. 8 ; 
         FIG. 10  is a cross-sectional view that bisects the insertion cap of  FIGS. 8 and 9 . 
         FIG. 11  is a perspective view showing a first end of a strain relief boot of the fiber optic connector of  FIG. 1 ; 
         FIG. 12  is a perspective view showing a second end of the strain relief boot of  FIG. 11 ; 
         FIG. 13  is a cross-sectional view that longitudinally bisects the strain relief boot of  FIGS. 11 and 12 . 
         FIG. 14  is an exploded, perspective view of a second fiber optic connector in accordance with the principles of the present disclosure; 
         FIG. 15  is a cross-sectional view that longitudinally bisects the fiber optic connector of  FIG. 14 ; 
         FIG. 16  is a perspective view showing a first side of a half-piece of a rear housing of the fiber optic connector of  FIG. 14 ; 
         FIG. 17  is a perspective view showing a second side of the half-piece of  FIG. 16 . 
         FIG. 18  is side view showing the second side of the half-piece of  FIGS. 16 and 17 ; 
         FIG. 19  is a perspective view showing a first end of a first insertion cap that can be used with the fiber optic connector of  FIG. 14 ; 
         FIG. 20  is a perspective view showing a second end of the insertion cap of  FIG. 19 ; 
         FIG. 21  is a cross-sectional view that longitudinally bisects the insertion cap of  FIGS. 19 and 20 ; 
         FIG. 22  is a perspective view showing a first end of a second insertion cap that can be used with the fiber optic connection of  FIG. 14 ; 
         FIG. 23  is a perspective view showing a second end of the insertion cap of  FIG. 22 ; 
         FIG. 24  is a cross-sectional view that longitudinally bisects the insertion cap of  FIGS. 22 and 23 ; 
         FIG. 25  is a cross-sectional view that longitudinally bisects a prior art fiber optic adapter; 
         FIG. 26  is a cross-sectional view taken along section line  26 - 26  of  FIG. 2 ; 
         FIG. 27  is a top view of a prior art LC style fiber optic connector; 
         FIG. 28  is a cross-sectional view that longitudinally bisects the fiber optic connector of  FIG. 27 ; 
         FIG. 29  is a perspective, exploded view of a third fiber optic connector having features with inventive aspects in accordance with the principles of the present disclosure; 
         FIG. 30  is a partially assembled perspective view of the fiber optic connector of  FIG. 29 ; 
         FIG. 31  is a fully assembled perspective view of the fiber optic connector of  FIG. 29 ; 
         FIG. 32  is a top view of the fiber optic connector of  FIG. 29 ; 
         FIG. 33  is a cross-sectional view that longitudinally bisects the fiber optic connector of  FIG. 29 ; 
         FIG. 34  illustrates a perspective view of two of the fiber optic connectors of  FIG. 29  coupled to a duplex LC fiber optic adapter; 
         FIG. 35  is a side view of the fiber optic connectors coupled to a duplex LC fiber optic adapter of  FIG. 34 ; 
         FIG. 36  is a top view of the fiber optic connectors coupled to a duplex LC fiber optic adapter of  FIG. 34 ; 
         FIG. 37  illustrates a perspective view of two of the fiber optic connectors of  FIG. 29  coupled together by a clip to form a duplex fiber optic connector; 
         FIG. 38  is a top view of the duplex fiber optic connector of  FIG. 37 ; 
         FIG. 39  is a perspective view of a front housing of the fiber optic connector of  FIG. 29 ; 
         FIG. 40  is a side view of the front housing of the fiber optic connector of  FIG. 39 , with a portion of the front housing broken-away to illustrate the internal configuration thereof; 
         FIG. 41  is a perspective view of a rear housing of the fiber optic connector of  FIG. 29 ; 
         FIG. 42  is a cross-sectional view that longitudinally bisects the rear housing of  FIG. 41 ; 
         FIG. 43  is a cross-sectional view that longitudinally bisects the insertion cap of the fiber optic connector shown in  FIG. 29 ; 
         FIG. 44  is a perspective view of a strain relief boot of the fiber optic connector of  FIG. 29 ; 
         FIG. 45  is a cross-sectional view that longitudinally bisects the strain relief boot of  FIG. 41 ; 
         FIG. 46  is a perspective, exploded view of a fourth fiber optic connector having features with inventive aspects in accordance with the principles of the present disclosure; 
         FIG. 47  is a partially assembled perspective view of the fiber optic connector of  FIG. 46 ; 
         FIG. 48  is a fully assembled perspective view of the fiber optic connector of  FIG. 46 ; 
         FIG. 49  is a top view of the fiber optic connector of  FIG. 46 ; 
         FIG. 50  is a cross-sectional view that longitudinally bisects the fiber optic connector of  FIG. 46 ; 
         FIG. 51  is a perspective view of a rear housing of the fiber optic connector of  FIG. 46 ; 
         FIG. 52  is a front view of the rear housing of  FIG. 51 ; 
         FIG. 53  is a cross-sectional view taken along line  53 - 53  of  FIG. 52 ; 
         FIG. 54  is a cross-sectional view taken along line  54 - 54  of  FIG. 53 ; 
         FIG. 55  is a cross-sectional view taken along line  55 - 55  of  FIG. 54 ; 
         FIG. 56  is a perspective view of an insertion cap that can be used with the fiber optic connector of  FIG. 46 ; 
         FIG. 57  is cross-sectional view that bisects the insertion cap of  FIG. 56 ; 
         FIG. 58  is a cross-sectional view taken along line  58 - 58  of  FIG. 57 ; 
         FIG. 59  is a cross-sectional view taken along line  59 - 59  of  FIG. 57 ; 
         FIG. 60  is a rear perspective view of an example embodiment of a crimp sleeve that might be used to anchor the optical fiber to the connector housing of a fiber optic connector; 
         FIG. 61  is a rear view of the crimp sleeve of  FIG. 60 ; 
         FIG. 62  is a cross-sectional view taken along lines  62 - 62  of  FIG. 61 ; 
         FIG. 63  is a rear perspective view of another example embodiment of a crimp sleeve that might be used to anchor the optical fiber to the connector housing of a fiber optic connector; 
         FIG. 64  is a rear view of the crimp sleeve of  FIG. 63 ; and 
         FIG. 65  is a cross-sectional view taken along lines  65 - 65  of  FIG. 61 ; 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  illustrate a first fiber optic connector  20  in accordance with the principles of the present disclosure. The fiber optic connector  20  has a total length Li that extends from a distal end  22  of the fiber optic connector  20  to a proximal end  24  of the fiber optic connector  20 . The fiber optic connector  20  includes a ferrule assembly  26  that mounts adjacent the distal end  22  of the fiber optic connector  20 . The ferrule assembly includes a ferrule  28 , a hub  30  and a spring  31 . The ferrule assembly  26  mounts at least partially within a connector housing  32  including a distal housing portion  34  that interconnects with a proximal housing portion  36 . In one embodiment, the distal housing portion  34  snaps over ribs  37  provided on the proximal housing portion  36  to interlock the two housing portions together. The fiber optic connector  20  also includes a release sleeve  38  that slidably mounts over the connector housing  32 . The fiber optic connector  20  further includes an insertion cap  40 A that mounts inside a proximal end  42  of the proximal housing portion  36  and a crimp sleeve  44  that mounts around the exterior of the proximal end  42  of the proximal housing portion  36 . The proximal end  24  of the fiber optic connector  20  is configured to receive, anchor and provide strain relief/bend radius protection to a fiber optic cable  46 . The fiber optic cable  46  includes a jacket  48  surrounding at least one optical fiber  50 . The fiber optic cable  46  also includes a strength layer  52  formed by a plurality of strength members (e.g., reinforcing fibers such as aramid yarn/Kevlar) positioned between the optical fiber  50  and the jacket  48 . A distal end portion of the strength layer  52  is crimped between the crimp sleeve  44  and the exterior surface of the proximal end  42  of the proximal housing portion  36  so as to anchor the strength layer  52  to the connector housing  32 . The optical fiber  50  is routed through the total length Li of the fiber optic connector  20  and includes a distal portion  54  secured within the ferrule  28 . The fiber optic connector  20  further includes a strain relief boot  56  mounted at the proximal end  24  of the fiber optic connector  20  for providing strain relief and bend radius protection to the optical fiber  50 . 
     It will be appreciated that the fiber optic connector  20  is adapted to be mechanically coupled to a like fiber optic connector by an intermediate fiber optic adapter.  FIG. 25  shows an example fiber optic adapter  58  that can be used to couple two of the fiber optic connectors  20  together. The fiber optic adapter  58  includes an adapter housing  59  defining opposite, coaxially aligned ports  60 ,  62  for receiving two of the fiber optic connectors desired to be coupled together. The fiber optic adapter  58  also includes an alignment sleeve  64  for receiving and aligning the ferrules  28  of the fiber optic connectors desired to be connected together. The fiber optic adapter  58  further includes latches  66  for mechanically retaining the fiber optic connectors  20  within their respective ports  60 ,  62 . The latches  66  can be configured to engage shoulders  68  provided on the distal housing portions  34  of the fiber optic connectors  20  being coupled together. Further details regarding the fiber optic adapter  58  can be found in U.S. Pat. No. 5,317,633, which is hereby incorporated by reference in its entirety. 
     In the depicted embodiment of  FIG. 1 , the release sleeve  38  is shown as a conventional SC release sleeve. When the release sleeve  38  is mounted on the connector housing  32 , the release sleeve  38  is free to slide back-and-forth in distal and proximal directions relative to the connector housing  32  along a central longitudinal axis  70  of the fiber optic connector  20 . When the fiber optic connector  20  is inserted within one of the ports  60 ,  62  of the fiber optic adapter  58 , the keying rail  72  provided on the release sleeve  38  ensures that the fiber optic connector  20  is oriented at the appropriate rotational orientation relative to the fiber optic adapter  58 . When the fiber optic connector  20  is fully inserted within its corresponding port  60 ,  62 , the latches  66  snap into a latching position in which the latches engage the shoulders  68  of the connector housing  32  to prevent the fiber optic connector  20  from being proximally withdrawn from the port  60 ,  62 . The release sleeve  38  is provided to allow the fiber optic connector  20  to be selectively withdrawn from its respective port  60 ,  62 . Specifically, by pulling the release sleeve  38  in a proximal direction, ramps  74  of the release sleeve disengage the latches  66  of the fiber optic adapter  58  from the shoulders  68  of the fiber optic connector  20  thereby allowing the fiber optic connector  20  to be proximally withdrawn from its respective port  60 ,  62 . 
     Referring to  FIG. 2 , the ferrule  28  of the ferrule assembly  26  includes a distal end  76  and a proximal end  78 . The distal end  76  projects distally outwardly beyond a distal end of the connector housing  32  and the proximal end  78  is secured within the ferrule hub  30 . When the connector housing  32  is assembled as shown at  FIG. 2 , the ferrule hub  30  and the spring  31  are captured between the distal housing portion  34  and the proximal housing portion  36  of the connector housing  32 . As so configured, the spring  31  is configured to bias the ferrule  28  in a distal direction relative to the connector housing  32 . When two of the fiber optic connectors  20  are interconnected, their ferrules  28  are forced to move in proximal directions relative to their respective connector housings  34  against the bias of their respective springs  31 . The movement is along the central axes  70  of the mated fiber optic connectors  20 . 
     Referring to  FIGS. 2 and 26 , the jacket  48  of the fiber optic cable  46  preferably has a relatively small outer diameter D 1 . In certain embodiments, the outer diameter D 1  can be less than 2 millimeters, or less than 1.5 millimeters, less than equal to about 1.2 millimeters. In certain embodiments, the optical fiber  50  within the jacket  48  can include a core  90 , a cladding layer  92  surrounding the core and one or more coating layers  94  surrounding the cladding layer  92 . In certain embodiments, the core  90  can have an outer diameter of about 10 microns, the cladding layer  92  can have an outer diameter of about 125 microns, and the one or more coating layers  94  can have an outer diameter in the range of about 240 to 260 microns. The strength layer  52  provides tensile reinforcement to the cable  46 . The strength layer  52  relatively closely surrounds the coating layer  94  of the optical fiber  50 . In addition to providing tensile strength to the cable  46 , the strength layer  52  also functions as a separator for separating the optical fiber  50  from the outer jacket  48 . In certain embodiments, no buffer layer or buffer tube is provided between the coating layer  94  of the optical fiber  50  and the strength layer  52 . Further details regarding the fiber optic cable  46  can be found in U.S. Pat. No. 8,548,293, which is hereby incorporated by reference in its entirety. 
     As shown at  FIG. 2 , the optical fiber  50  extends through the total length Li of the fiber optic connector  20 . For example, the optical fiber  50  extends through the strain relief boot  56 , the insertion cap  40 A, the connector housing  32  and the ferrule  28 . In certain embodiments, a portion of the optical fiber  50  extending proximally from the ferrule  28  through the fiber optic connector  20  to the jacketed portion of the fiber optic cable  46  includes only the core  90 , the cladding layer  92  and the one or more coating layers  94 . The portion of the optical fiber  50  extending through the ferrule  28  typically only includes the core  90  and the cladding layer  92 . A distal most end face of the optical fiber  50  is preferably polished as is conventionally known in the art. 
     As shown at  FIG. 2 , the insertion cap  40 A (see  FIGS. 5-7 ) is mounted within the proximal end  42  of the proximal housing portion  36  of the connector housing  32 . The insertion cap  40 A has an inner diameter D 2  sized to correspond with the outer diameter of the coating layer  94 . In alternative embodiments, it may be desirable to cover/protect the portion of the optical fiber  50  extending through the connector housing  32  with a protective layer such as a 900 micron tube (e.g., a 900 micron furcation tube). To accommodate such a protective tube, the insertion cap  40 A can be replaced with an insertion cap  40 B (see  FIGS. 8-10 ) having an inner diameter D 3  that is larger than the inner diameter D 2 . In certain embodiments, inner diameter D 3  can correspond to the outer diameter of protective buffer tube provided about the coating layer  94  of the optical fiber  50  within the connector housing  32 . 
     The fiber optic connector  20  is a pull-proof connector in which the strength layer  52  of the fiber optic cable  46  is anchored to the connector housing  32  thereby preventing tensile loads from being transferred to the ferrule assembly  26 . Because of this configuration, movement of the ferrule  28  in a proximal direction relative to the connector housing  32  causes the optical fiber  50  to be forced/displaced in a proximal direction relative to the connector housing  32  and the jacket  48  of the fiber optic cable  46 . In the depicted embodiment, the ferrule  28  has a maximum axial displacement AD in the proximal direction during the connection process. The axial displacement AD creates an excess fiber length having a length equal to the length of the axial displacement AD. In certain embodiments, the maximum axial displacement AD can be 0.035 inches. 
     With regard to the axial displacement AD described above, it is significant that the relatively small diameter of the fiber optic cable  46  and the lack of open space within the interior of the jacket  48  do not allow the cable  46  to readily accommodate acceptable macrobending of the optical fiber  50  within the jacket  48  when the ferrule  28  is forced in a proximal direction relative to the connector housing  32 . Therefore, to prevent signal degradation related to microbending caused by the axial displacement of the optical fiber  50  in the proximal direction, the connector  20  is itself preferably configured to take-up the excess fiber length corresponding to the axial displacement. To take-up the excess fiber length, the fiber optic connector  20  includes features that encourage a controlled, predictable and repeatable macrobend of the optical fiber  50  within the connector housing  32  when the ferrule  28  is forced in a proximal direction relative to the connector housing  32 . In this way, the fiber optic connector  20  itself accommodates the acceptable macrobending of the optical fiber  50  such that the optical fiber  50  does not need to slide within the jacket  48  of the fiber optic cable  46  and does not require the optical fiber  52  to macro or microbend within the jacket  48  of the fiber optic cable  46  when the ferrule  28  is forced in a proximal direction relative to the connector housing  32 . 
     To prevent unacceptable signal degradation, the fiber optic connector  20  is preferably designed to take-up the optical fiber length corresponding to the axial displacement AD. For example, referring to  FIG. 2 , the connector housing  32  includes a fiber take-up region  100  that extends generally from a proximal end of the spring  31  to the proximal end  42  of the proximal housing portion  36 . The fiber take-up region  100  includes a passage  101  that extends along the axis  70 . As shown at  FIG. 2 , the passage  101  has an intermediate section  102 , a distal section  104  and a proximal section  106 . The intermediate section  102  has an enlarged transverse cross-sectional area as compared to the transverse cross-sectional areas of the distal and proximal sections  104 ,  106 . The transverse cross-sectional areas are taken along planes perpendicular to the longitudinal axis  70  of the connector  20 . The distal section  104  and the intermediate section  102  are defined by the proximal housing portion  36  (see  FIG. 4 ). The distal section  104  of the passage  101  has a necked configuration with a neck portion  104   a  positioned between transition portions  104   b  and  104   c . The neck portion  104   a  defines a minimum cross-dimension CD 1  (e.g., an outer diameter) and minimum transverse cross-sectional area of the distal section  104 . The transition portion  104   b  provides a gradual reduction in transverse cross-sectional area (i.e., a funnel or taper toward the longitudinal axis  70 ) as the transition portion  104   b  extends from the intermediate section  102  of the passage  101  toward the neck portion  104   a . The transition portion  104   c  provides a gradual increase in transverse cross-sectional area (i.e., a funnel or taper away from the longitudinal axis  70 ) as the transition portion  104   c  extends from the neck portion  104   a  toward the spring  31 . 
     The proximal section  106  of the passage  101  is defined by the inside of the insertion cap  40 A or the insertion cap  40 B (depending on which one is selected). For ease of explanation, the description herein will primarily refer to the insertion cap  40 A (see  FIGS. 5-7 ). A minimum cross-dimension CD 2  (e.g., an outer diameter) of the proximal section  106  is defined near a proximal end of the insertion cap  40 A. The proximal section  106  includes a transition  106   a  that provides a reduction in transverse cross-sectional area as the transition  106   a  extends in a proximal direction from the intermediate section  102  of the passage  101  toward the minimum cross-dimension CD 2 . A chamfer  109  at the proximal end of the insertion cap  40 A provides an increase in transverse cross-sectional area as the chamfer  109  extends proximally from the minimum cross-dimension C 2 . The chamfer  109  can assist in providing bend radius protection with respect to the fiber passing through the insertion cap  40 A. It will be appreciated that by using the insertion cap  40 B, the minimum diameter provided by the insertion cap can be enlarged so as to accommodate a productive buffer tube covering the optical fiber  50  within the passage  101 . 
     In certain embodiments, the minimum cross-dimension CD 1  is greater than the minimum cross-dimension CD 2 . In other embodiments, the minimum cross-dimension CD 1  is at least twice as large as the minimum cross-dimension CD 2 . In other embodiments, the minimum cross-dimension CD 1  is generally equal to the minimum cross-dimension CD 2 . In still further embodiments, a maximum cross-dimension CD 3  of the passage  101  is at least 1.5 times or 2 times as large as the minimum cross-dimension CD 1 . In still other embodiments, the maximum cross-dimension CD 3  of the passage  101  is at least 2, 3 or 4 times as large as the minimum cross-dimension CD 2 . 
     It will be appreciated that the length and transverse cross-sectional dimensions of the fiber take-up region  100  are selected to accommodate the excess length of fiber corresponding to the axial displacement distance AD. When the ferrule  28  is pushed in a proximal direction, the configuration of the fiber take-up region  100  causes the optical fiber  50  to move from a generally straight path SP along the axis  70  to a path that follows generally along a single macrobend  120  (shown at  FIG. 2 ) that extends along the surface of the fiber take-up region  100  from the distal section  104  through the intermediate section  102  to the proximal section  106 . The increase in length between the straight path and the curved path equals the axial displacement distance AD. The transitions  104   b ,  106   a  provided at the proximal and distal sections  104 ,  106  of the passage  101  help to encourage the fiber to form the single microbend in a predictable, repeatable manner as the ferrule  28  is forced in a proximal direction relative to the connector housing  32  during a connection process. In certain embodiments, the fiber take-up region is configured to take up at least 0.015 inches, or at least 0.025 inches or at least 0.035 inches of excess fiber length. 
     In addition to the advantages provided above, the transition  104   b  also facilitates assembly of the fiber optic connector  20 . Specifically, during assembly, the optical fiber  50  is inserted in a distal direction through the proximal end  42  of the connector housing  32  and is directed through the length of the connector housing into the ferrule  28 . The transition  104   b  assists in guiding the fiber  50  into the ferrule  28  during the fiber insertion process. 
     Referring to  FIG. 7 , the insertion cap  40 A includes a sleeve portion  110  having a cylindrical outer surface that fits inside the proximal end  42  of the connector housing  32 . The insertion cap  40 A also includes a flange  112  at a proximal end of the sleeve portion  110 . The flange  112  projects radially outwardly from the cylindrical outer surface of the sleeve portion  110  and forms a proximal end of the insertion cap  40 A. The flange  112  abuts against the proximal end  42  of the connector housing  32  when the insertion cap  40 A is inserted therein. The inside of the insertion cap  40 A defines the proximal section  106  of the passage  101  which extends in a proximal to distal direction through the insertion cap  40 A. The insertion cap  40 B has a similar configuration as the insertion cap  40 A, except the minimum inner cross-dimension CD 2  (e.g., inner diameter) of the insertion cap  40 B is larger than the minimum cross-dimension CD 2  of the insertion cap  40 A so as to better accommodate a protective tube covering the coated fiber  50  within the connector housing  32 . 
     The use of the insertion cap  40 A or the insertion cap  40 B allows the proximal end  42  of the connector housing  32  to have a relatively large open transverse cross-sectional area which corresponds to the maximum cross-dimension CD 3  of the passage  101 . This large transverse cross-sectional area is advantageous because it facilitates delivering potting material (e.g., and adhesive material such as epoxy) to the back side of the ferrule  28  during assembly for potting the fiber  50  within the ferrule  28 . Typically, a needle can be used to deliver potting material to the ferrule  28 . The large cross-sectional area provides better access for allowing a needle to be inserted through the proximal end of the connector housing  32  to accurately injecting potting material into the ferrule  28 . 
     Referring to  FIG. 1 , the crimp sleeve  44  of the fiber optic connector  20  includes a sleeve portion  140  and a stub portion  142  that projects proximately outwardly from a proximal end of the sleeve portion  140 . A radial in-step  141  is provided between the sleeve portion  140  and the stub portion  142  such that the sleeve portion  140  has a larger diameter than the stub portion  142 . A passage extends axially throughout the length of the crimp sleeve  44 . The passage has a smaller diameter through the stub portion  142  and a larger diameter through the sleeve portion  140 . When the fiber optic connector  20  is assembled, the sleeve portion  140  is crimped about the exterior surface of the connector housing  32  adjacent the proximal end  42  of the connector housing  32  (see  FIG. 2 ). The exterior surface of the connector housing  32  can be textured (e.g., knurled, ridged, provided with small projections, etc.) to assist in retaining the crimp on the housing  32 . Preferably, a distal portion of the strength layer  52  of the fiber optic cable  46  is crimped between the sleeve portion  140  and the exterior surface of the connector housing  32  such that the strength layer  52  of the cable  46  is anchored relative to the connector housing  32 . 
     In certain embodiments (e.g., as shown in  FIG. 1 ), the sleeve portion  140  of the crimp sleeve may include an annular rib  143  on an exterior surface thereof. The annular rib  143  may provide additional material for the crimp sleeve  44  at spots or regions that will tend to deform when the crimp sleeve  44  is crimped at the sleeve portion  140 . 
     The stub portion  142  fits within a pocket  144  provided within the strain relief boot  56 . The stub portion  142  coaxially aligns with the central longitudinal axis  70  of the fiber optic connector  20 . The insertion cap  40 A is captured between the proximal end  42  of the connector housing  32  and the crimp sleeve  44 . In this way, the crimp sleeve  44  assists in retaining the insertion cap  40 A in the proximal end  42  of the connector housing  32 . The insertion cap  40 A can also be held within the connector housing  22  by an adhesive material such as epoxy. 
     In certain embodiments, it can be advantageous to crimp the stub portion  142  of the crimp sleeve against the outer jacket  48  of the fiber optic cable  46  such that any space between the outer jacket  48  and the optical fiber  50  is eliminated within the cable  46  and the optical fiber  50  gets pinched against the inner surface of the jacket  48  of the fiber optic cable  46 . As such, the optical fiber  50 , as well as the strength layer  52 , can be anchored relative to the connector housing  32  adjacent the proximal end  42  thereof. The location where the optical fiber  52  itself is crimped to the connector housing  32  may be called the fiber anchor location  51  (see  FIG. 2 ). 
     Anchoring the optical fiber  50  relative to the proximal end  42  of the connector housing  32  can isolate the movable ferrule assembly  26  from the rest of the fiber optic cable  46  that is not pinched or crimped to the connector housing  32 . This is advantageous because, if the optical fiber  50  were not anchored to the connector housing  32 , in certain instances, the optical fiber  50  may slide within the outer jacket  48 , interfering with the predictability and the repeatability of the macrobending that takes place within the fiber take-up region  100  when the ferrule  28  is forced in a proximal direction. For example, if a long fiber optic cable  46  were to be spooled around a spool structure, the fiber  50  might tend to migrate toward the inner diameter side of the cable within the cable and might move a different distance than the outer jacket  48  itself. If the fiber  50  were to slide within the outer jacket  48  toward the ferrule assembly  26 , that would create extra fiber within the connector, interfering with the predictability of the acceptable macrobending that takes place within the fiber take-up region  100 . 
     In other instances, for example, if a tensile load was applied to the cable in a proximal direction away from the connector, the outer jacket  48  of the cable  46  might stretch inelastically and the optical fiber  50  could slidably move within the jacket, relative to the jacket, causing a pulling force on the ferrule assembly  26 . Thus, by anchoring the optical fiber  50  to the connector housing  32  adjacent the proximal end  42  through the use of the crimp sleeve  44 , the movable ferrule assembly  26  is isolated from the rest of the fiber optic cable  46  that is not crimped to the connector housing  32 . As such, axial load is not transferred in either direction across the anchor location. The anchor restricts/prevents relative movement between the optical fiber and the jacket at the fiber anchor location. In this way, the portion of the fiber within the connector and the portion of the fiber within the main length of the cable are mechanically isolated from one another. The connector of the present disclosure, thus, can operate as designed and utilize the fiber take-up region  100  to provide for a predictable and a repeatable macrobend when the ferrule is moved in a proximal direction relative to the connector housing  32 . 
       FIGS. 60-65  illustrate two different embodiments of crimp sleeves  544 ,  644  that include annular ribs on an exterior surface of the stub portions thereof. Even though the other embodiments of the crimp sleeves disclosed in the present application can be used to crimp the stub portion thereof against the outer jacket  48  of the fiber optic cable  46  such that the optical fiber  50  gets pinched against the inner surface of the jacket  48  of the fiber optic cable  46 , the crimp sleeves  544  and  644  shown in  FIGS. 60-65  may provide for additional material for the stub portions of the crimp sleeve at spots or regions that might tend to deform when the crimp sleeve is crimped at the stub portion. 
     In the embodiment of the crimp sleeve  544  shown in  FIGS. 60-62 , the stub portion  542  of the sleeve  544  includes a first annular rib  543  at a proximal end  547  thereof and a second annular rib  545  at an intermediate location between the proximal end  547  and the radial in-step  541  of the crimp sleeve  544 . 
     In the embodiment of the crimp sleeve  644  shown in  FIGS. 63-65 , the stub portion  642  of the sleeve  644  includes a single, wider annular rib  643  at a proximal end  647  thereof. 
     In the depicted embodiment, the fiber anchor location is defined as being at a location that is not at a splice location where two segments of optical fiber are spliced together. In the present disclosure, the optical fiber is directly terminated in the connector and the connector is not a splice-on connector. 
     To assemble the fiber optic connector  20 , the ferrule assembly  26  is first loaded into the distal housing portion  34  of the connector housing  32 . Next, the proximal housing portion  36  is connected to the distal housing  34  (e.g., by a snap fit connection) such that the ferrule hub  30  and the spring  31  are captured within the connector housing  32  at a location between the distal housing portion  34  and the proximal housing portion  46 . Next, an epoxy needle is inserted through the proximal end  42  of the proximal housing portion  36  and is used to inject epoxy into the fiber passage defined through the ferrule  28 . Once the epoxy has been applied, the epoxy needle is removed and the insertion cap  40 A or the insertion cap  40 B is inserted into the proximal end  42  of the connector housing  32 . Thereafter, the strain relief boot  56  and the crimp sleeve  44  are inserted over the fiber optic cable  46  and a distal end portion of the cable is prepared. 
     As part of the cable preparation process, the jacket  48  is stripped from the distal end portion of the optical fiber. Also, the coating layers  94  are stripped from the distalmost portion of the optical fiber  50  intended to be inserted through the passage defined by the ferrule  28 . Moreover, the strength layer  52  is trimmed to a desired length. Once the fiber optic cable  46  has been prepared, the distal end portion of the optical fiber  50  is inserted through the insertion cap  40 A and into the ferrule  28  which has been potted with epoxy. During the insertion process, the transition  104   b  assists in guiding the distalmost end portion of the optical fiber  50  into the ferrule  28 . Once the fiber insertion process has been completed, the crimp sleeve  44  is slid distally over the proximal end  42  of the connector housing  32  and used to crimp the distal end of the strength layer  52  about the exterior surface of the connector housing  32  adjacent to the proximal end  42 . The strain relief boot  56  is then slid distally over the crimp sleeve  44  and proximal end  42  of the housing  32 . Finally, the release sleeve  38  is inserted over the distal end  22  of the fiber optic connector  20  and snapped into place over the connector housing  32 . 
     Referring to  FIGS. 11-13 , the strain relief boot  56  of the fiber optic connector  20  includes a distal end  200  and an opposite proximal end  202 . The strain relief boot defines an inner passage  204  that extends through the boot from the proximal end  202  to the distal end  200 . When the boot  56  is mounted on the connector housing  32 , the inner passage  204  aligns with the central longitudinal axis  70  of the fiber optic connector  20 . The boot  56  includes a connection portion  206  positioned adjacent the distal end  200  and a tapered, strain relief portion  208  positioned adjacent the proximal end  202 . The connection portion  206  has a larger cross-dimension than a corresponding cross-dimension of the tapered, strain relief portion  208 . A transition portion  210  is positioned between the connection portion  206  and the tapered, strain relief portion  208 . An outer surface of the transition portion provides a gradual increase in cross-dimension as the outer surface extends from the tapered, strain relief portion  208  to the connection portion  206 . The outer surface of the transition portion  210  can be pushed to facilitate inserting the connection portion  206  over the proximal end  42  of the connector housing  32  during assembly of the fiber optic connector  20 . Further details about the boot  56  are provided in U.S. Provisional Patent Application Ser. No. 61/452,935, which has been assigned Attorney Docket No. 2316.3201USP1, which is entitled STRAIN RELIEF BOOT FOR A FIBER OPTIC CONNECTOR, and which has been filed on a date concurrent with the filing of the present application. 
     For the connector  20 , the proximal housing portion  36 , the insertion cap  40 A and the insertion cap  40 B are all depicted as machined metal parts.  FIGS. 14-24  show various parts of another fiber optic connector  20 ′ in accordance with the principles of the present disclosure. The connector  20 ′ has been modified with respect to the connector  20  so as to include a proximal housing portion  36 ′, an insertion cap  40 A′ and an insertion cap  40 B′ which are all made of molded plastic. The other components of the connector  20 ′ are the same as the connector  20 . In  FIG. 15 , the insertion cap  40 B′ is shown installed within the connector  20 ′, and a protective outer tube  149  is shown protecting the portion of the coated optical fiber  50  that extends from the proximal side of the ferrule to the boot. The proximal housing portion  36 ′ is formed by two molded half-pieces  36   a  that mate together to form the proximal housing portion  36 ′. The half-pieces  36   a  can be bonded together with an adhesive or held together mechanically by one or more fasteners such as crimps. According to certain embodiments, the half-pieces  36   a  may be held together by a snap-fit interlock. According to the example embodiment depicted in  FIGS. 14-24 , each half piece  36   a  includes flexible cantilever arms  41  on one side  43  of the half-piece  36   a  and notches  45  on the radially opposite side  47  of the half-piece  36   a  (see  FIGS. 16-17 ). Each cantilever arm  41  defines a tab  49  at the end of the arm  41  that is configured to snap over shoulders  51  defined at the notches  45  when two half-pieces  36   a  are interlocked together. The cantilever arms  41  and the notches  45  of one half-piece  36   a  are provided on opposite sides with respect to the arms  41  and notches  45 , respectively, of the other half-piece  36   a . As such, when the two half-pieces  36   a  are brought together for a snap-fit interlock, the cantilever arms  41  of one half-piece  36   a  align with the notches  45  of the opposing half-piece  36   a  and vice versa. 
     The molding process used to manufacture the proximal housing portion  36 ′ allows the interior of the proximal housing portion  36 ′ to be provided with a continuous curve  150  that extends along the length of the take-up region of connector  20 ′. The insertion caps  40 A′ and  40 B′ are similar to the insertion caps  40 A,  40 B except the parts are molded plastic parts with the inner diameter transitions at the proximal and distal ends of the caps have a more curved profile. 
       FIGS. 27 and 28  illustrate a prior art fiber optic connector  220  in the form of a conventional LC connector. As shown in  FIGS. 27 and 28 , the conventional LC connector  220  includes a connector housing  222  defining a distal housing portion  224  and a proximal housing portion  226 . The LC connector  220  includes a ferrule assembly  228  defined by a ferrule  230 , a hub  232 , and a spring  234 . A proximal end  236  of the ferrule  230  is secured within the ferrule hub  232 . When the LC connector  220  is assembled, the ferrule hub  232  and the spring  234  are captured between the distal housing portion  224  and the proximal housing portion  226  of the connector housing  222  and a distal end  238  of the ferrule  230  projects distally outwardly beyond a distal end  240  of the connector housing  222 . The spring  234  is configured to bias the ferrule  230  in a distal direction relative to the connector housing  222 . 
     According to certain embodiments, the distal housing portion  224  may be formed from a molded plastic. The distal housing portion  224  defines a latch  242  extending from a top wall  244  of the distal housing portion  224  toward the proximal end  246 , the latch  242  extending at an acute angle with respect to the top wall  244  of the distal housing portion  224 . The distal housing portion  224  also includes a latch trigger  248  that extends from the proximal end  246  of the distal housing portion  224  toward the distal end  240 . The latch trigger  248  also extends at an acute angle with respect to the top wall  244 . The latch trigger  248  is configured to come into contact with the latch  242  for flexibly moving the latch  242  downwardly. 
     As is known in the art, when the fiber optic connector  220  is placed in an LC adapter  250  for optically coupling light from two optical fibers together, the latch  242  functions to lock the fiber optic connector  220  in place within the adapter  250 . The fiber optic connector  220  may be removed from the adapter  250  by depressing the latch trigger  248 , which causes the latch  242  to be pressed in a downward direction, freeing catch portions  252  of the latch  242  from the fiber optic adapter  250 . 
     The region of the distal housing portion  224  from where the latch trigger  248  extends defines a pin hole  254 . The pin hole  254  is configured to receive a pin for forming a duplex LC connector by coupling two simplex connectors  220  in a side-by-side orientation. 
     Still referring to  FIGS. 27 and 28 , a strain relief boot  256  is slid over a proximal end  258  of the proximal housing portion  226  and snaps over a boot flange  260  to retain the boot  256  with respect to the connector housing  222 . The proximal end  258  of the proximal housing portion  226  defines a crimp region  262  for crimping a fiber optic cable&#39;s strength layer to the proximal housing portion  226 , normally with the use of a crimp sleeve (not shown). The exterior surface  264  of the proximal housing portion  226  defining the crimp region  262  can be textured (e.g., knurled, ridged, provided with small projections, etc.) to assist in retaining the crimp on the housing  222 . 
     As discussed above with respect to the embodiments of the SC connector shown in  FIGS. 1-26 , movement of the ferrule  230  of the LC connector in a proximal direction relative to the connector housing  222  causes the optical fiber to be forced/displaced in a proximal direction relative to the connector housing  222  and the jacket of the fiber optic cable. However, in the conventional LC connector  220  shown in  FIGS. 27 and 28 , the passage  266  defined by the proximal housing portion  226  that extends along the longitudinal axis of the connector  220  defines a generally uniform inner diameter DLC similar in size to the diameter of the portion of the optical fiber that includes the core, the cladding layer and the one or more coating layers. As such, the proximal housing portion  226  of a conventional LC connector  220  does not include a fiber take-up region to prevent signal degradation related to microbending caused by the axial displacement of the optical fiber in the proximal direction. 
       FIGS. 29-45  illustrate various parts of a third fiber optic connector  300  in accordance with the principles of the present disclosure. The connector  300  includes inventive features similar to those shown and described for the SC type connectors  20 ,  20 ′ of  FIGS. 1-26 , however, is provided in an LC connector footprint. 
     Referring to  FIGS. 29-45 , the fiber optic connector  300  includes a connector housing  301  including a distal housing portion  302  and a proximal housing portion  304 . The distal housing portion  302  is similar in configuration to that of a conventional LC connector and includes a ferrule assembly  306  defined by a ferrule  308 , a hub  310 , and a spring  312  mounted therein. The ferrule hub  310  and the spring  312  are captured within the distal housing portion  302  by the proximal housing portion  304  of the connector housing  301 . The distal housing portion  302  defines slots  314  that are configured to receive ribs  316  formed at a distal end  318  of the proximal housing portion  304  for snap-fitting the two housing portions  302 ,  304  together. 
     An insertion cap  320  having features similar to insertion caps  40 A and  40 A′ is inserted into a proximal end  322  of the proximal housing portion  304 . As discussed above with respect to the SC style connectors  20 ,  20 ′, an alternative embodiment of an insertion cap having a larger inner diameter for accommodating a protective tubing can also be used. A crimp sleeve  324  is inserted over the proximal end  322  of the proximal housing portion  304  and captures the insertion cap  320  thereagainst. The crimp sleeve  324  is used to crimp a fiber optic cable in a manner similar to that described above for the SC style connectors  20 ,  20 ′. 
     A strain relief boot  326  is mounted over the proximal end  322  of the proximal housing portion  304 . The strain relief boot  326  includes a connection portion  328  defining a generally circular inner passage  330  (see  FIGS. 44 and 45 ). An annular inner lip  332  defined at a distal end  334  of the strain relief boot  326  mounts over a generally round boot flange  336  defined on the outer surface  338  of the proximal housing portion  304 . When the strain relief boot  326  is mounted over the proximal housing portion  304 , the distal end  334  of the strain relief boot  326  abuts against a stop ring  340 . As shown in  FIG. 33 , the stop ring  340  defines a conical configuration  342  along the longitudinal direction of the connector  300 , the ring  340  tapering down as it extends from a proximal end  344  toward a distal end  346 . 
     When the fiber optic connector  300  is fully assembled, the connector  300  retains the overall outer dimension of a conventional LC connector such that two fiber optic connectors  300  can be mounted side by side in a standard duplex configuration.  FIGS. 37 and 38  illustrate two of the fiber optic connectors  300  mounted together using a duplex clip  348 .  FIGS. 34-36  illustrate two of the fiber optic connectors  300  mounted in a standard duplex LC adapter  250  in a side by side configuration. 
     As noted above, as shown in  FIGS. 33, 42, and 43 , the proximal housing portion  304  and the insertion cap  320  of the connector  300  are configured to provide a fiber take-up spacing  350  for allowing macrobending of the optical fiber within the connector housing  301 , in a similar fashion to that described above for the SC style connectors  20 ,  20 ′. For the connector  300 , the proximal housing portion  304  and the insertion cap  320  are depicted as machined metal parts. 
       FIGS. 46-59  illustrate various parts of a fourth embodiment of a fiber optic connector  400  in accordance with the principles of the present disclosure. The connector  400  has been modified with respect to the connector  300  so as to include a proximal housing portion  402  and an insertion cap  404  which are made of molded plastic. In addition, unlike the proximal housing portion  304  of the connector  300  described above, which has a fiber take-up region  350  defined by a circular passage  352  extending from the proximal end  322  of the proximal housing portion  304  to the distal end  318  thereof, the proximal housing portion  402  of the connector housing  406  defines an obround passage  408  that transitions to a generally circular passage  410  as it extends from a proximal end  412  of the proximal housing portion  402  to the distal end  414  thereof. As shown in  FIG. 54 , the passage defines an obround configuration  408  from the proximal end  412  until it reaches the transition portion  416  coming before the neck portion  418 . The obround portion  408  of the passage is provided to increase the predictability of the bending of the fiber as the fiber is exposed to axial displacement within the connector  400  and control the direction of the bend. 
     As shown in the cross-sectional views provided in  FIGS. 52 and 53 , the obround portion  408  of the passage defines a larger cross-dimension CDO along a first direction DO 1  (taken along lines  55 - 55  of  FIG. 54 ) than a second direction DO 2  (taken along lines  53 - 53  of  FIG. 52 ). In addition, by providing an obround internal passage  408 , the size of the opening  420  at the proximal end  412  of the proximal housing portion  402  is increased relative to the annular circular opening  354  of the connector  300  shown in  FIGS. 29-45  when that opening  420  is measured along the longer cross dimension CDO of the obround passage  408 . By providing an obround passage  408 , the sidewall  422  defined along the longer cross dimension CDO of the obround passage  408  is able to be decreased relative to a uniform sidewall  356  that is provided about the circular opening  354  of the connector  300 . 
     The insertion cap  404  of the connector  400  defines a stub portion  426  having an exterior obround configuration  428  to match that of the proximal end  412  of the proximal housing portion  402 . As shown in  FIGS. 56-59 , the insertion cap  404  also defines an internal passage  430  that transitions from a generally circular opening  432  to an obround configuration  434  as the passage  430  extends from the proximal end  436  to the distal end  438  of the insertion cap  404 . The obround portion  434  of the passage  430  cooperates with the obround portion  408  of the internal passage of the proximal housing portion  402  in controlling the direction of the fiber bend. 
     Although in the foregoing description, terms such as “top”, “bottom”, “front”, “back”, “rear”, “right”, “left”, “upper”, and “lower may have been used for ease of description and illustration, no restriction is intended by such use of the terms. The connectors described herein can be used in any orientation, depending upon the desired application. 
     The above specification, examples and data provide a description of the inventive aspects of the disclosure. Many embodiments of the disclosure can be made without departing from the spirit and scope of the inventive aspects of the disclosure.