WO2015017170A1

WO2015017170A1 - Fiber optic connector assembly with particle-collecting cover

Info

Publication number: WO2015017170A1
Application number: PCT/US2014/047505
Authority: WO
Inventors: David Joseph HESSONG; Wesley Allan Yates
Original assignee: Corning Optical Communications LLC
Current assignee: Corning Research and Development Corp
Priority date: 2013-07-31
Filing date: 2014-07-22
Publication date: 2015-02-05
Anticipated expiration: 2016-01-31

Abstract

A fiber optic assembly includes a connector, optical fiber, and cover. The connector has a ferrule that defines an end face of the connector. The optical fiber extends through the ferrule to the end face of the connector, and an end of the optical fiber is polished proximate to the end face. The cover, which is received over the end face of the connector, includes a body and a particle collection layer coupled to the body so as to overlay the end face and the polished end of the optical fiber. The particle collection layer is configured to draw loose particulates of dust and/or debris from the end face of the connector upon removal of the cover from the connector.

Description

FIBER OPTIC CONNECTOR ASSEMBLY WITH PARTICLE- COLLECTING COVER

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 61/860,473, filed on July 31, 2013, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

[0002] The present disclosure relates generally to fiber optic assemblies and more particularly to covers for protecting and cleaning an end face of a fiber optic connector.

[0003] Fiber optic connectors typically include a ferrule that surrounds and supports an optical fiber on an end face of the connector. The optical fiber is finely polished to provide a clean and clear interface with an adjoining optical fiber supported by mating component within an adapter that receives the connector. Small scratches (e.g., on the order of micrometers) and dust particles can greatly impact the performance of the connector. Accordingly, connectors are often transported and stored with dust caps/covers that are designed to shield the end face.

[0004] Even with a dust cap, a connector may still become contaminated with particulates. Particles from the interior of the dust cap may migrate to the end face of the connector, especially when the connectors are being transported, presumably due to movement of the connectors and corresponding air currents mobilizing the particles. Additionally, micro- passages may facilitate communication of very small particles to the end face of the connector even when the dust cap is installed. Such passages may be inherently present due to limits of tolerances in the dimensions of the connector bodies and dust caps.

[0005] There are also situations where the dust caps may be temporarily removed prior to the connectors being used in operation, thereby exposing the end faces to particles before the dust caps are placed back on the connectors. For example, after a cable assembly including a fiber optic connector has been installed or setup to support a fiber optic network, the cable assembly may be tested to verify its operation and check its performance before the fiber optic network is operational. The testing involves removing the dust caps to connect test equipment to the connectors. The test equipment is eventually disconnected, at which point the dust caps may be replaced if mating components for the connectors are not yet installed and/or not yet ready to be optically coupled to the connectors. As can be appreciated, there are periods of time during such testing where the end faces of the connectors are left exposed and unprotected by the dust caps.

[0006] Despite the extremely small size of particles like those mentioned above, attenuation and damage to the end face of a connector may still be produced by the particles. Signal losses due to the associated attenuation may be pose a problem, particularly for connectors used with fiber optic networks that operate at ever increasing speeds due to improvements in the rate of data transmission. Accordingly, end users are typically required to clean connectors before installation. Much time is required for cleaning. There is also some risk of damaging connectors due to cleaning. Therefore, a need exists for cover/cap that helps provide a cleaner and more damage-free end face of a fiber optic connector.

SUMMARY

[0007] One embodiment of the disclosure relates to a fiber optic assembly comprising a connector, optical fiber, and cover. The connector includes a ferrule that defines an end face of the connector. The optical fiber extends through the ferrule to the end face of the connector. The cover, which is received over the end face of the connector, includes a body and particulate removal means coupled to the body. The particulate removal means is configured to draw loose particulates of dust and debris from the end face of the connector upon removal of the cover from the connector.

[0008] An additional embodiment of the disclosure also relates to a fiber optic assembly comprising a connector, optical fiber, and cover. Again, the connector includes a ferrule that defines an end face of the connector. The optical fiber extends through the ferrule to the end face of the connector, and an end of the optical fiber is polished proximate to the end face. The cover in this embodiment, which is also received over the end face of the connector, includes a body and a particle collection layer coupled to the body so as to overlay the end face of the connector and the polished end of the optical fiber. The particle collection layer may comprise, for example, a spray-on adhesive, an adhesive tape, a polymer film, or any other layer configured to draw loose particulates of dust and/or debris from the end face of the connector upon removal of the cover from the connector.

[0009] In one variant of the embodiment just mentioned, the body of the cover defines a cavity in which the ferrule is received. The particle collection layer is positioned within the cavity. Such a variant may resemble a traditional cover or dust cap for a fiber optic connector from the outside, but has a novel construction/configuration because of the particle collection layer. In another variant of the embodiment just mentioned, the body of the cover may have a shape corresponding to a receptacle of an adapter that is configured to receive the ferrule. Such a variant may therefore resemble a traditional adapter version of a dust cap in some respects, but also has a novel construction/configuration because of the particle collection layer.

[0010] Yet another embodiment of this disclosure relates to a fiber optic assembly comprising a connector, optical fiber, and cover. Once again, the connector includes a ferrule that defines an end face of the connector. The optical fiber extends through the ferrule to the end face of the connector, and an end of the optical fiber may be polished proximate to the end face. The cover, which is received over the end face of the connector, includes a body and a particle collection layer bonded to the body and the end face of the connector. The particle collection layer has a first bond strength with respect to the body and a second bond strength with respect to the end face, with the first bond strength being greater than the second bond strength.

[0011] An additional embodiment of this disclosure relates to a fiber optic assembly comprising a connector, optical fiber, and cover. Once again, the connector includes a ferrule that defines an end face of the connector. The optical fiber extends through the ferrule to the end face of the connector, and an end of the optical fiber is polished proximate to the end face. The cover, which is received over the end face of the connector, includes a body having a cover surface with a shape corresponding to the end face of the connector. The cover further includes a particle collection layer applied over the cover surface. The particle collection overlays the end face on the ferrule and the polished end of the optical fiber when the cover is received on the connector, but is coupled to the body of the cover and configured to draw loose particulates of dust and debris from the end face of the connector upon removal of the cover from the connector.

[0012] Additional features and advantages will be set forth in the detailed description which follows. Additional features and advantages will also be readily apparent to those skilled in the art based on the description, or recognized by practicing the embodiments disclosed.

[0013] Indeed, it is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims. [0014] The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments), and together with the description serve to explain principles and operation of the various embodiments. Persons skilled in the technical field of fiber optic connectors will appreciate how features and attributes associated with embodiments shown in one of the drawings may be applied to embodiments shown in others of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig. 1 is a perspective view of an example of a fiber optic connector, shown in the form of a multi-fiber push-on/pull-off (MTP) fiber optic connector;

[0016] Fig. 2 is an exploded perspective view of a fiber optic assembly according to one embodiment of this disclosure including the fiber optic connector of Fig. 1 ;

[0017] Fig. 3 is a schematic diagram of a an end face of a fiber optic connector;

[0018] Fig. 4 is a schematic diagram of a portion of a fiber optic assembly including a connector and cover according to an exemplary embodiment;

[0019] Fig. 5A is a schematic diagram of a portion of a fiber optic assembly including a connector and cover according to another exemplary embodiment;

[0020] Fig. 5B is a schematic diagram of a portion of a fiber optic assembly including a connector and cover according to yet another exemplary embodiment;

[0021] Fig. 6 is an exploded perspective view of a fiber optic assembly according to another embodiment of this disclosure; and

[0022] Fig. 7 is a schematic diagram of a portion of the fiber optic assembly of Fig. 6.

DETAILED DESCRIPTION

[0023] Various embodiments will be further clarified by the following examples. To this end, Figs. 1 and 2 illustrate one example of a fiber optic assembly 10 including a fiber optic connector 12 ("connector") attached to a fiber optic cable 14, such as an indoor flame - retardant jumper, a connectorized tether, or another type of fiber optic cable. Although the connector 12 is shown in the form of a multi-fiber push-on/pull-off (MTP-type) connector, the description below relates to features that may apply to fiber optic assemblies involving other connector designs. This includes not only other types of multi-fiber connectors, but also different types of single-fiber connectors (e.g., SC, ST, LC, FC, and MU-type connectors). Indeed, the description below relates primarily to a cover/cap 16 used in connection with the connector 12 rather than the structure or details of the connector itself.

[0024] With this in mind, the connector 12 in the embodiment shown includes a ferrule 20 received in a ferrule holder 22, which in turn is received within a shell or housing 24. The ferrule 20 may be constructed from plastics, ceramics, and/or metals. The ferrule 20 defines an end face 26 of the connector 12, which in the embodiment shown includes alignment features in the form of guide pins 28. Other embodiments will be appreciated where the ferrule 20 includes different alignment features, such as alignment bores, or no alignment features. The connector 12 may further include a spring 30 for absorbing strain from the cable 14, a fiber guide 32 coupled to the ferrule holder 22, a crimp band 34, and/or other features. Different types of boots 36 may also be provided to prevent over-bending of different fiber optic cables (e.g., jacketed and non-jacketed cables) used with the connector 12.

[0025] In a manner not shown herein, an optical fiber from the fiber optic cable 14 extends through a bore in the ferrule 20 and to the end face 26 of the connector 12. During factory manufacturing, an end 40 of the optical fiber is typically polished proximate to (e.g., flush with, slightly beyond, or beneath) the end face 26. For example, the end 40 of the optical fiber may be polished within 100 micrometers of the end face 26. In some embodiments, including the exemplary embodiment shown in Figs. 1 and 2, at least five additional optical fibers extend through the ferrule 20. Each of the optical fibers are spaced apart and aligned with one another on the end face 26 of the connector 12, forming a straight row of circular end cross-sections (e.g., ). The optical fibers may be bound together in a fiber ribbon or be independent fibers loosely passing through a buffer tube or jacket cavity within the fiber optic cable 14.

[0026] Fig. 3 illustrates a portion of the end face 26 laterally surrounding an optical fiber 44, which includes a core 46 and a cladding 48. Loose particulates 50 of dust and debris may be present on the end face 26 and/or polished end 40 of the optical fiber 44. In general, the cap 16 (Fig. 2) is received on the connector 12 and configured to remove the particulates 50 from the end face 26 upon removal from the connector 12. In other words, the cap 16 includes particulate removal/collection means that collects the particulates 50 when placed on the connector 12 and retains the particulates 50 when removed from the connector 12. The advantages of integrating the particulate removal means into the cap 16 will be more apparent based on the description below. [0027] Now referring to Fig. 4, one embodiment of the cap includes a body 60 and a particle collection layer 62 coupled to the body 60. The body 60 defines a cavity 64 configured to receive the ferrule 20. In the embodiment shown, the cavity 64 is defined by inner walls 66 of the body 60 extending from a rear opening to a cover surface 68. The cover surface 68 has a shape that substantially corresponds to the end face 26 of the connector 12. Thus, in the embodiment shown, the cover surface 68 includes alignment bores 70 for receiving the guide pins 28 of the connector 12. The inner walls 66 may likewise define a profile that substantially corresponds to, ferrule holder 22, and/or housing 24 that supports the ferrule).

[0028] The particle collection layer 62 functions as the particulate removal means in this embodiment. In general, the particle collection layer 62 is positioned in the cavity 64 and on/over at least a portion of the cover surface 68. When the cap 16 is positioned on the connector 12, the particle collection layer 62 overlays at least a portion of the end face 26 of the connector 12. The particle collection layer 62 may even be deformable in some embodiments and conform to the shape of the end face 26. The particle collection layer 62 also overlays the polished ends 40 (Fig. 1) of the optical fibers 44. The entire surface of each polished end 40 may contact the particle collection layer 62, and in some embodiments the particle collection layer 62 may provide an airtight seal that isolates the polished ends 40 from the environment surrounding the end face 26 of the connector 12.

[0029] Although there may be some bonding or other form of attraction between the particle collection layer 12 and the end face 26 and/or polished ends 40, the particle collection layer 62 is coupled to the body 60 in such a manner so as to remain with body 60 upon removing the cap 16 from the connector 12. For example, the particle collection layer

62 may be coupled to the body 60 by bonding (e.g., adhesive bonding, mechanical bonding, bonding with static electrical charges) to the cover surface 68. The bond between the particle collection layer 62 and body 60 in such embodiments is greater than any attraction/bonding there may be between the particle collection layer 62 and both the end face 26 of the connector 12 and the polished ends 40 of the optical fibers 44 when the cap 16 is installed on the connector 12. The particle collection layer 62 is nevertheless configured to draw loose particulates of dust and/or debris from the end face 26 of the connector 12 upon removal of the cap 16 because of the attraction or otherwise. Various possibilities/embodiments for the particle collection layer 62 will now be described to better appreciate these general principles.

[0030] For example, the particle collection layer 62 may comprise an adhesive agent bonded to the body 60 of the cap 16. The adhesive agent may be a curable liquid adhesive, such an acrylic -based or silicon-based adhesive, sprayed or applied in some other manner to the cover surface 68. The adhesive agent in such embodiments contacts both the cover surface 68 of the body 60 and the end face 26 of the connector 12. However, the adhesive agent has a greater bond strength with the cover surface 68 than with the end face 26. In other words, the adhesive agent has a first bond strength with respect to the cap 16 and a second bond strength with respect to the end face 26, with the first bond strength being greater than the second bond strength. Additionally, the adhesive agent has cohesion and bonding with itself that is greater than the second bond strength. The result is that, upon removing the cap 16 from the connector 12, the end face 26 and polished ends 40 of the optical fibers 44 are free of residue from the adhesive agent. Stated differently, the adhesive agent leaves little or no residue on the end face 26 of the connector 12 and the polished ends 40 of the optical fibers 44. Note that the second bond strength is nevertheless sufficient so that the particle collection layer 62 is still configured to draw loose particulates of dust and debris from the end face 26 of the connector 12 upon removal of the cap 16 and thereby clean the end face 26.

[0031] In other embodiments, the particle collection layer 62 may comprise an adhesive agent as part of a tape or similar structure. For example, the particle collection layer 62 may include a substrate or backing to which the adhesive agent is bonded. The substrate is coupled to the body 60 of the cap 16 in a manner that is more secure than the bond between the adhesive agent and substrate, which in turn is more secure/stronger than any bonding between the adhesive agent and the end face 26 of the connector 12 and/or polished ends 40 of the optical fibers 44. According to one embodiment, the substrate has a first bond strength with respect to the cap 16 and a second bond strength with respect to the adhesive agent, which in turn has a third bond strength with respect to the end face 26 of the connector 12. The first and second bond strengths are greater than the third bond strength such that, upon removing the cap 16 from the connector 12, the end face 26 and polished ends 40 of the optical fibers 44 are free of residue from the adhesive agent. As with the previously- mentioned example, the adhesive agent leaves little or no residue on the end face 26 of the connector 12 and the polished ends 40 of the optical fibers 44. Again, the bond strength between the adhesive agent and end face 26 (i.e., the third bond strength in this example) is nevertheless sufficient so that the particle collection layer 62 is still configured to draw loose particulates of dust and debris from the end face 26 of the connector 12 upon removal of the cap 16 and thereby clean the end face 26. [0032] Different ways of coupling the substrate to the cap 16 to provide these effects will be appreciated. For example, the tape may be two-sided. Stated differently, the particle collection layer 62 may comprise a tape with different adhesive agents on first and second sides of the substrate. The adhesive agent on the first side of the substrate ("first adhesive agent") bonds the particle collection layer 62 to the body 60, while the adhesive agent on the second side of the substrate ("second adhesive agent") overlies the end face 26 of the connector 12 and the polished ends 40 of the optical fibers 44 when the cap 16 is received on the connector 12. To this end, the second adhesive agent may be similar to the adhesive agent already discussed, having a bond strength with respect to the end face 26 that is less than a bond strength the second adhesive agent has with respect to the substrate. The bond strength of the second adhesive agent with respect to the end face 26 is also less than bond strengths that the first adhesive agent has with respect to the substrate and the body 60 of the connector 12.

[0033] In other embodiments, the particle collection layer 62 maybe mechanically coupled to the body 60 of the connector 12. Fig. 5B illustrates one example of how the cavity 64 in the body 60 may be configured to retain the particle collection layer 62. A groove 80 may be provided in the cavity proximate one or more edges of the cover surface 68. The particle collection layer 62 may be "snapped" in place or otherwise positioned in the groove 80. Other methods of mechanical attachment, including the use of fasteners (not shown), will also be appreciated. Additionally, embodiments where some combination of mechanical coupling, adhesive bonding, or other coupling techniques will be appreciated.

[0034] One example of another coupling technique involves the use of static electrical charges. Accordingly, the particle collection layer 62 may comprise a polymer sheet, such as a polyester film, configured to provide the static electrical charges. The polymer sheet may be used in combination with an adhesive agent, with the adhesive agent serving to bond the polymer sheet to the body 60 of the cap 16 and static electrical charges serving to bond the particle collection layer 62 to the end face 26 of the connector 12 in a weaker manner, or vice-versa, with static electrical charges serving to bond the polymer sheet to the body 60 of the cap 16 and the adhesive agent serving to bond the particle collection layer 62 to the end face 26 of the connector 12 in a weaker manner. Embodiments will also be appreciated where the particle collection layer 62 only comprises a polymer sheet coupled to the body 60 of the connector 12 by mechanical features, static electrical charges, or both.

[0035] It should be noted that the configuration of the body 60 shown in Fig. 4 is merely for illustrative purposes. The shape of the body 60 may differ depending on the type of connector 12 on which the cap 16 is received and the nature/type of fiber optic assembly in which the cap 16 and connector 12 are used. For example, the body 60 may be configured to be used with a "non-pinned" connector 12 (i.e., a connector 12 not having guide pins 28), as shown in Fig. 5A. The body 60 may also be configured to function as an adapter plug/cap, as shown in Figs. 6 and 7.

[0036] In particular, Figs. 6 and 7 illustrate a fiber optic assembly 100 including an adapter 102 configured to receive the connector 12 on one side and a component to which the connector 12 mates (not shown) on another side such that the optical coupling/mating of the connector 12 and component takes place within the adapter 102. Prior to coupling the mating component to the connector 12, however, a cover/cap 104 may be used to extend into the adapter 102 and thereby protect the end face 26 ofthe connector 12. To this end, the adapter 100 defines a receptacle 106 between first and second ends 108, 110 thereof. The ferrule 20 of the connector 12 extends into the receptacle 106 from the first end 108, and the cap 104 extends into the receptacle 106 from the second end 110. The cap 104 comprises a body 60 and particle collection layer 62 like the previously discussed embodiments. Thus, the principles discussed above with respect to the previous embodiments may be equally applicable to the embodiment shown in Figs. 6 and 7.

[0037] In some variants of the embodiment shown in Figs. 6 and 7, the cap 104 includes a handle 120 integrally formed with the body 60 (e.g., molded as a unitary component) or coupled to the body 60 (e.g., when the handle is formed as a separate component). In some embodiments, the handle 120 may comprise a first material, such as a rigid plastic, and the body may comprise a second material, such as a foam or flexible polymer, that is less rigid than the first material. Further variants will be appreciated by persons skilled in the technical field of fiber optic connectors.

[0038] Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claims below. As an example, the cap 16 may further include an outer shell (not shown) surrounding the body 60 and being similar to the handle 120 of the cap 104 so as to comprise a material that is more rigid than the material of the body 60 (i.e., the outer shell may comprise a first material and the body may comprise a second material that is less rigid than the first material).

[0039] Since modifications, combinations, sub-combinations and variations of the disclosed embodiments incorporating the spirit and substance of the disclosure 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. [0040] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim 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.

Claims

What is claimed is:

1. A fiber optic assembly, comprising:

a connector including a ferrule defining an end face of the connector;

an optical fiber extending through the ferrule to the end face of the connector, wherein an end of the optical fiber is polished proximate to the end face; and

a cover received over the end face of the connector, the cover including a body and a particle collection layer coupled to the body so as to overlay the end face of the connector and the polished end of the optical fiber;

wherein the particle collection layer is configured to draw loose particulates of dust and debris from the end face of the connector upon removal of the cover from the connector.

2. The fiber optic assembly of claim 1, wherein the body of the cover defines a cavity in which the ferrule is received and the particle collection layer is positioned in the cavity.

3. The fiber optic assembly of either claim 1 or 2, wherein the body of the cover has a cover surface with a shape corresponding to the end face of the connector, and further wherein the particle collection layer is applied to the cover surface.

4. The fiber optic assembly of any of claims 1 -3, wherein the particle collection layer is coupled to the body by bonding, and further wherein the bond between the particle collection layer and body is greater than any bonding between the particle collection layer and both the end face of the connector and the polished end of the optical fiber.

5. The fiber optic assembly of any of claims 1 -4, wherein the particle collection layer comprises a substrate coupled to the body of the cover and an adhesive agent bonded to the substrate, the adhesive agent overlaying the end face of the connector and the polished end of the optical fiber.

6. The fiber optic assembly of claim 5, wherein the particle collection layer comprises a tape with different adhesive agents on first and second sides of the substrate, wherein the adhesive agent on the first side of the substrate bonds the particle collection layer to the body of the cover and the adhesive agent on the second side of the substrate overlies the end face of the connector and the polished end of the optical fiber, and wherein bond strength of the adhesive agent on the first side of the substrate is greater than bond strength of the adhesive agent on the second side of the substrate.

7. The fiber optic assembly of any of claims 1 -6, wherein the particle collection layer is mechanically coupled to the body.

8. The fiber optic assembly of any of claims 1 -7, wherein the particle collection layer comprises a polymeric sheet configured to provide a static electrical charge.

9. The fiber optic assembly of any of claims 1 -4, wherein the particle collection layer comprises an adhesive agent bonded to the body of the cover, the adhesive agent being a spray-on, curable liquid adhesive.

10. The fiber optic assembly of any of claims 1 -9, wherein the cover further includes an outer shell that surrounds body, and further wherein the outer shell comprises a first material and the body comprises a second material that is less rigid than the first material.

11. The fiber optic assembly of any of claims 1 -9, further comprising:

an adapter to which the connector is coupled, the adapter defining a receptacle extending between first and second ends thereof, the ferrule of the connector extending into the receptacle from the first end of the adapter, and the cover extending into the receptacle from the second end of the adapter.

12. The fiber optic assembly of claim 11, wherein the cover further includes a handle integrally formed with or coupled to the body.

13. The fiber optic connector assembly of claim 12, wherein the handle comprises a first material and the body comprises a second material that is less rigid than the first material.

14. The fiber optic assembly of any of claims 11 -13, wherein the body of the cover has a shape corresponding to the shape of the receptacle.

15. The fiber optic assembly of any of claims 1 -14, wherein the entire surface of the polished end of the optical fiber contacts the particle collection layer.

16. The fiber optic assembly of any of claims 1-15, wherein the particle collection layer provides an airtight seal that isolates the polished end of the optical fiber from an

environment surrounding the end face of the connector.

17. The fiber optic assembly of any of claims 1 -16, wherein the particle collection layer is deformable and conforms to the shape of the end face of the connector.

18. A method of manufacturing a fiber optic assembly according to any of claims 1 -17, comprising:

extending the optical fiber through a bore in the ferrule to the end face of the connector;

polishing an end of the optical fiber;

positioning the end of the optical fiber proximate to the end face of the connector; and positioning the cover over the end face of the connector so that the particle collection layer overlays the end face and the polished end of the optical fiber.

19. The method of claim 18, wherein positioning the cover further comprises pressing the body against to the end face of the connector such that the particle collection layer directly contacts the polished end of the optical fiber with no air gaps present between the particle collection layer and the polished end of the optical fiber.

20. The method of either claim 18 or 19, further comprising:

removing the cover from the end face of the connector, wherein the particle collection layer remains coupled to the body when the covered is removed and draws loose particulates of dust and debris from the end face of the connector.