WO2014008657A1

WO2014008657A1 - T-style, push-on, non-contacting fiber optic connector dust cap

Info

Publication number: WO2014008657A1
Application number: PCT/CN2012/078593
Authority: WO
Inventors: Anh Ngoc Nguyen; Xuewu LEI
Original assignee: Amphenol Corporation
Priority date: 2012-07-13
Filing date: 2012-07-13
Publication date: 2014-01-16

Abstract

A cap for covering an optical ferrule of a fiber-optic connector. The cap may include an inner cavity, compliant longitudinal ribs on an outer surface of a first portion of the cap, and a stopping feature. The cap may be installed over the optical ferrule and into an opening in a housing of the fiber-optic connector. The longitudinal ribs may deform into contact with the housing and provide frictional retention of the cap over the ferrule. The stopping feature may prevent the cap from contacting an end of the optical ferrule. In various embodiments, the cap does not contact the optical ferrule and forms a sealed enclosure to protect the optical ferrule from contamination or damage.

Description

T-STYLE, PUSH-ON, NON-CONTACTING FIBER OPTIC

CONNECTOR DUST CAP

FIELD OF THE INVENTION

[0001] The invention relates to apparatus and methods for enclosing an exposed end of an optical ferrule in a fiber optic connector.

BACKGROUND

[0002] Manufactured fiber-optic connector assemblies are used to make fiber-to-fiber connections in fiber-optic networks where connect and disconnect functionality may be desired. In some cases, fiber-optic connectors may be used to connect optical fiber to an instrument or a signal routing device. There exists a variety of standardized fiber optic connectors, with types LC and SC connectors being among the more common assemblies that are currently manufactured and marketed.

[0003] When a fiber-optic connector is not connected to a mating connector, a part of the connector that supports an end of the information-carrying optical fiber, typically in the form of an opticalferrule, is exposed and at risk for contamination or physical damage. Since the active optical area of the optical ferrule is small, on the order of microns, a small scratch or piece of dust can significantly degrade or even disrupt the optical signal, and render a connector inoperable. Contamination and physical damage can readily occur under extreme handling conditions, and even occur under normal handling or shipping. Accordingly, dust caps and covering mechanisms have been developed to cover the optical ferrule when the connector is disengaged.

[0004] Most dust caps currently used to cover the optical ferrule rely on friction between the optical ferrule and the dust cap, or friction between an inner diameter of a portion of the connector housing surrounding the ferrule and the dust cap. The former type of dust caprelies on direct contact between the optical ferrule and dust cap. The latter version canavoid physical contact of the cap with the ferrule, and instead rely on direct contact between the dust cap and the connector housing to hold the dust cap over the optical ferrule.

[0005] One example of a dust cap lOOof the latter type is depicted in FIGS. 1A-1C. FIG. 1A depicts a side view of a dust cap that has been designed for an LC connector. FIG. IB shows an end view of the same dust cap, and FIG. 1C shows a cross-sectional view of the dust cap 100. The cap includes a cavity 120 that admits the optical ferrule of the LC connector. There is a conically shaped portion 110 on an outer surface of the cap that radially wedges against a housing of the LC connector when the dust cap 100 is placed over the optical ferrule.

SUMMARY

[0010] The present invention relates to apparatus and methods for covering an optical ferrule of a fiber-optic connector .According to one embodiment, a dust cap of the present invention is configured to be installed over an optical ferrule that extends from an opening in a housing of a fiber-optic connector such that, when installed, the dust cap does not contact the ferrule. In some embodiments, the dust cap comprises compliant ribs that contact the housing and retain the dust cap in the opening and over the optical ferrule. In some embodiments, the dust cap may be formed from a compliant material, and include at least one stopping feature that prevents the dust cap from being pushed into contact with an end of the optical ferrule during installation of the dust cap.

[0011] The inventors have recognized several problems with dust caps of previous designs. Dust caps that rely on direct contact and friction between the dust cap and the optical ferrule can transfer dirt, mold release agents, or other contamination from inside the dust cap to the ferrule. Such a transfer of unwanted debris can result in contamination of both an active optical endface of the optical ferrule and the outer diameter of the ferrule. Additionally the action of pushing the cap onto and pulling the cap off of the ferrule can lead to static charging of ceramic or steel used to make the ferrule. A statically charged ferrule can attract airborne dust and other undesirable contamination to the ferrule, further contaminating the optical ferrule.

[0012] For dust caps that rely on contact between the cap and a housing of the connector, such as the one shown in FIGS. 1A-1C, the inventors have found that the cap design lends itself to poor retention as both the connector housing and the cap are commonly made from relatively stiff and smooth materials. For example, the dust cap may be manufactured from high-density polyethylene. Though such caps may initially adequately cover the optical ferrule, the friction between the cap and housingtends to be small, allowing the caps to fall off during normal shipping and handling. Further, the inventors have found that the conical portion 110 of the cap 100 used to improve cap retention can lead to problems. The conical portion can increase the potential for damage to either the inner diameter of the fiber-optic connector and/or the outer diameter of the cap when the force between cap and connector is excessiveduring cap installation and removal. Additionally, the design shown in FIGS. 1 A- 1C tends to create a positive pressure in the cavity 120 during installation, which can tend to force the cap back off the connector, and create a negative pressure during cap removal, which can draw contaminants toward the optical ferrule with an inrush of air.

[0013] To circumvent the foregoing problems, the inventors have conceived of a dust cap for a fiber-optic connector that is configured to cover an optical ferrule extending from an opening in a housing of the fiber-optic connector. According to some embodiments, the dust cap comprisesa first portion that includes a wall around an inner cavity and longitudinal ribs on an outer surface of the wall. The first portion may have a first outer dimension transverse to the longitudinal ribs. The dust cap may further include a second portion connected to the first portion. The inner cavity may be sized to accommodate an outer dimension of an optical ferrule of the fiber-optic connector. According to some embodiments, the longitudinal ribs are compliant, and the first outer dimension may be equal to or greater than an inner dimension of the opening in the housing of the fiber-optic connector.

[0014] Also contemplated by the inventors is a method for covering an optical ferrule that is in an opening of a housing of a fiber-optic connector. According to one embodiment, the methodcomprises installing, into the opening and over an end of the optical ferrule, a cap comprising a first portion having a wall extending around an inner cavity and longitudinal ribs on an outer surface of the wall. The cap may be installed such that the longitudinal ribs contact a first surface of the housing. The method may further include moving the cap until a stopping feature in the cap contacts a second surface of the housing.

[0015] Some embodiments include a fiber-optic connector comprising an optical ferrule containing an optical fiber, wherein the optical ferrule extends from an opening in a housing of the fiber optic connector. The fiber-optic connector may further include a removable cap covering an end of the optical ferrule, the removable cap comprises a first portion that includes a wall around an inner cavity and longitudinal ribs on an outer surface of the wall. The first portion may have a first outer dimension transverse to the longitudinal ribs, and the longitudinal ribs may contact a first surface of the opening of the housing. In various embodiments, at least the longitudinal ribs are compliant and deform when in contact with the first surface so as to retain the cap over the optical ferrule.

[0016] The foregoing and other aspects, embodiments, and features of the present teachings can be more fully understood from the following description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The skilled artisan will understand that the figures, described herein, are for illustration purposes only. It is to be understood that in some instances various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention. In the drawings, like reference characters generally refer to like features, functionally similar and/or structurally similar elements throughout the various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the teachings. The drawings are not intended to limit the scope of the present teachings in any way.

[0018] FIGS. lA-lCdepict a dust cap for a fiber-optic connector of a known design.

[0019] FIGS. 2A-2D depict a dust cap for a fiber-optic connector, according to various embodiments.

[0020] FIG. 2E depicts an embodiment of a dust cap for a fiber-optic connector that comprises two materials.

[0021] FIG. 2F depicts a dust cap for a fiber-optic connector, according to one

embodiment.

[0022] FIG. 3 depicts a dust cap installed in a fiber-optic connector, according to one embodiment.

[0023] FIGS. 4A-4C depict additional embodiments of a dust cap for a fiber-optic connector.

[0024] FIGS. 5A-5C depict another embodiment of a dust cap for a fiber-optic connector.

[0025] The features and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings.

DETAILED DESCRIPTION

[0026] One embodiment of a dust cap 200 conceived by the inventors is depicted in FIG. 2A. A side view of the same embodiment is shown in FIG. 2B, and an end view of the cap 200 is shown in FIG. 2C. A cross sectional view of the dust cap is illustrated in FIG. 2D, according to one embodiment. The dust cap 200 may be installed over an optical ferrule 3 lOthat may or may not extendfrom an opening in a housing 320of a fiber-optic connector 300 (partially shown), as depicted in the cross-sectional diagram of FIG. 3 for example. In various embodiments, the cap 200 does not contact the ferrule 310 when installed. The dust cap 200, when installed, may form a sealed enclosure over the optical ferrule and can prevent contamination and physical damage of the optical ferrule 310 during handling and shipping of the fiber-optic connector. The connector 300 may be any suitable fiber-optic connector, e.g., an LC or SC type connector.

[0027] In some embodiments and referring now to FIG. 2A, the dust cap 200 comprises a first portion 210 and a second portion 212. In some embodiments, the dust cap 200 may be an integral structure, such that portions 210 and 212 are formed of a same type of a material. Such an integral structure may be formed, for example, by injection molding.

[0028] The first portion may comprise a wall 208 extending around an inner cavity 205. There may be an end surface 215 of the wall at a first end of the dust cap 200 that may be smooth and flat across the cap in some embodiments. The first portion 210 may be connected to the second portion 212, and there may be at least one protruding feature or stopping feature, e.g., step 240, on an outer surface of the cap 200. The step may include a surface facing the first end of the cap that is smooth and flat across the cap in some embodiments. As used herein, a description of a surface as being flat across the cap does not necessarily mean that the surface itself comprises flat portions. A surface being flat across the cap means that the surface may uniformly contact a flat surface across the span of the cap so as to form a seal.

[0029] The inner cavity 205 may extend into the dust cap 200 and be open at the first end of the cap. The inner cavity may otherwise be closed within the cap. The inner cavity 205 may be sized to accommodate an optical ferrule of a fiber-optic connector. In various embodiments, the optical ferrule may fit within the inner cavity 205 without touching an inner surface of the cap that defines the inner cavity 205. In some embodiments, the ferrule may contact at least a portion of the inner surface of the cap. According to some

embodiments, the inner surface of the cap is a distance between about 0.25 millimeter (mm) and about 3 mm from the optical ferrule. The distance between the inner surface of the cap and ferrule may be uniform in some embodiments, and may not be uniform in other embodiments. According to one embodiment, the distance between the exposed end of the optical ferrule 310 and the inner surface of the dust cap is about 0.5 mm.

[0030] The second portion 212 of the dust cap may include a shaft 250 and a protrusion 260 or several protruding features that aid in grasping the second portion 212 with fingers. In some embodiments, the outer surface of the second portion 212 may be varied in any suitable manner to improve grasping the second portion of the cap. The inner cavity 205 may extend within the second portion 212. The second portion of the cap may be sealed at the second end of the cap 200, and the protrusion 260 may be located near or at the second end of the cap as depicted in FIGS. 2A-2B. The second portion 212 may have additional protrusions 260 and/or other types of protrusions, e.g., ribs, stubs, tabs, on the outer surface to aid in grasping the end of the cap. According to some embodiments, there may be a plurality of protrusions 260, e.g., ribs, that run around a perimeter of the shaft 250.

[0031] The first portion 210 may have a first outer dimension ODi as measured across the cap. The first outer dimension may include heights of ribs 220 on opposite sides of the first portion 210. The second portion 212 may have a second outer dimension OD₂, and may additionally have a third outer dimension OD₃. The second outer dimension may be greater than the first outer dimension in some embodiments, e.g., so as to form step 240. The third outer dimension may be greater than the second outer dimension in some embodiments, e.g., so as to form protrusion 260. There may be other relative sizes of the outer dimensions ODi, OD₂, OD₃ in other embodiments, e.g., as depicted in FIG. 2F.

[0032] Though the dust cap 200 is shown in FIGS. 2A-2C as being substantially

cylindrical with substantially round cross sections, the cap may be formed in other

embodiments with other cross-sectional shapes, e.g., elliptical, square, rectangular, polygonal, for various types of fiber-optic connectors. In some implementations, the cross- sectional shape of the first portion may differ from the cross-sectional shape of the second portion. For example, the first portion may have a round cross section, and the second portion may have a square cross section.

[0033] On an outer surface of the wall 208 at the first portion 210, there may be a plurality of longitudinal ribs 220. The ribs may run uniformly along the outer wall, as depicted in FIG. 2A, according to one embodiment. In some embodiments, the ribs may not run uniformly along the outer wall. For example, their width may change along their length. Alternatively, or in addition, each rib may be interrupted along the wall, e.g., formed as sections of a rib. According to some embodiments, stubs may be used instead of or in addition to ribs. For example, a waffle-type pattern of stubs may be used. Although the ribs 220 are shown in FIGS. 2A-2C as having a width that is narrower than the space between the ribs, the width of the ribs may be equal to a space between the ribs in some embodiments, or the width of the ribs may be greater than a space between the ribs in some embodiments. Although the ribs are shown in FIG. 2A as being distributed uniformly around the wall 208, the ribs may not be distributed uniformly around the wall 208 in some embodiments. In some implementations, there may be a mixture of ribs of varying width on wall 208. In some implementations, there may be a mixture of ribs and stubs on wall 208. In yet other embodiments, the ribs 220 may be curved along the outer surface of the wall 208, e.g., in helical geometry. [0034] In various embodiments, ribs 220 are compliant. The longitudinal ribs 220 may be formed of a material that is softer than the material used for the connector housing 320.

Referring to FIG. 2B and FIG. 3, a first outer dimension ODi of the first portion 210 of the cap 200 may be equal to or larger than an inner dimension of an opening in the connector housing 320. The ribs 220 may deform to a greater extent than the housing 320 of the fiberoptic connector 300 when the cap 200 is installed in the connector over the optical ferrule 310. According to some embodiments, the ribs may have a Shore A hardness between about 30 and about 100. In some embodiments, the Shore A hardness of the ribs is between 60 and 95. In one embodiment, the Shore A hardness of the ribs is about 90. By deforming when installed over the optical ferrule 310 and in contact with housing 320, the longitudinal ribs 220 can establish superior frictional retention of the cap 200 to the connector 300 as compared to prior dust caps.

[0035] According to some embodiments, the dust cap 200 may be formed of a single material. For example, the dust cap may be formed by injection molding a polymer, elastomer, or a thermoplastic elastomer (TPE). Any suitable polymer or TPE may be used. In some embodiments, the material used may exhibit a Shore A hardness between about 30 and about 100 may be used. In one embodiment, the dust cap 200 may be formed of polypropylene. Other polymers that may be used to form the dust cap include polyethylene, polystyrene, polyvinyl fluoride, polyvinylchloride, polyvinylacetate, polymethylmethacrylate, polydimethylsiloxane, and polycarbonate.In one embodiment, the dust cap 200 may be formed of a TPE comprising a mix of polypropylene and ethylene propylene diene monomer (EDPM) rubber. Classes of TPE's that may be used to form all or a portion of the dust cap 200 include styrenic block copolymers, polyolefin blends, elastomeric alloys, thermoplastic polyurethanes, thermoplastic copolyester and thermoplastic polyamides. The material used to form the dust cap may be opaque to radiation carried by the optical fiber, though in some embodiments, the material may be clear or translucent. In some embodiments, the material may be clear, translucent, or opaque to visible radiation.

[0036] In other embodiments, the dust cap 200 may be formed from two or more materials that are bonded or fit together. FIG. 2E shows one embodiment of a dust cap formed from two materials. A first material may be used to form a first portion 211 of the dust cap that includes the longitudinal ribs 220. The first material may exhibit a Shore A hardness between about 30 and about 100, such that the longitudinal ribs deform and provide frictional retention of the cap when the cap is installed in the fiber-optic connector. A second material, having a hardness greater than that of the first material, may be used to form a second portion 221 of the dust cap. The first portion 211 may be bonded to the second portion 221, in some implementations. In some embodiments, the first portion 211 may be friction fit over the second portion 221. The step 240 may or may not be formed in the softer material of the first portion 211.

[0037] In some embodiments, a material for the dust cap or longitudinal ribs may be chosen according to the material's surface energy. A material having a surface energy that may favorably improve surface adhesion between the ribs 220 and the connector housing 320 may be selected. For example, the ribs may be formed of polydimethylsiloxane (PDMS or silicone) exhibiting a low surface energy that favors contact adhesion to many materials.

[0038] It will be appreciated that the compliant longitudinal ribs 220 of the dust cap exhibit several advantages over prior dust cap designs, such as the one shown in FIGS. 1A-1C. By deforming, the longitudinal ribs can provide superior frictional retention of the cap to the fiber-optic connector housing without risking damage to the connector upon insertion and removal of the dust cap 200. Further, the ribs provide venting of air upon installation and removal of the cap, so as to prevent formation of substantial positive or negative pressure within the cap's inner cavity 205. The absence of positive pressure removes a force that would tend to push the cap 200 out of the opening in the connector housing after installation of the cap. The absence of negative pressure upon removal of the cap prevents air-borne contaminants from being drawn toward the optical ferrule 310.

[0039] As depicted in FIG. 3, the maximum amount of insertion of the cap 200 into the fiber-optic connector 300 may be determined by the protrusion or step 240. The step 240 on the outer surface of the cap can provide a physical stop that determines a final position of the cap relative to the optical ferrule 310 and connector 300. According to some embodiments, the step 240 prevents the cap from being installed too far at the risk of undesirably contacting an inner surface of the cap to the exposed end face of the optical ferrule 310.

[0040] In a different embodiment, the end surface 215 of the cap (referring to FIG. 2A) may contact a surface of the connector housing 320 near the base of the ferrule 310 to prevent contact between an inner surface of the cap and the exposed end face of the ferrule.

According to some embodiments, the length of the inner cavity 205 may be longer than the length of the ferrule 310 extending from the body of the connector 300.

[0041] In various embodiments, the step 240, or surface 215, may form a seal when in contact with the connector housing 320, e.g., when the dust cap 200 is fully installed over the optical ferrule, so as to form a sealed enclosure around the optical ferrule 310. The seal may substantially reduce contamination reaching the optical ferrule 310. In some embodiments, the step 240 comprises a compliant rim, e.g., as depicted in FIG. 2D, that can deform to form a seal with the connector housing 320. The step 240, or surface 215, may include arounded or beveled edge (beveled edge shown in FIG. 2D) in some implementations, or may include a flat edge (shown in FIG. 2E).

[0042] According to some embodiments, the ends of the longitudinal ribs 220, and optionally the end of the wall 208, at a first end of the dust cap 200 may include bevels 230. FIGS. 2 A and 2B show bevels at the end of the longitudinal ribs and into a small portion of the wall 208. The bevels 230 may aid in alignment and installation of the cap. The bevels may permit one to insert initially a portion of the cap into the connector housing 320 at low force before applying a greater force to fully install the cap.

[0043] In some implementations, a large bevel 433 may be introduced into the first end of the cap alternatively to, or in addition to, the bevels at the ends of the longitudinal ribs, e.g., as depicted in FIGS. 4A-4C. The larger bevel 433 allows the dust cap to be initially installed at an angle with respect to fiber-optic connector and then aligned upon full insertion into the connector 300. The large bevel may also improve visibility of the optical ferrule during initial installation of the cap, and may relax alignment requirements during initial insertion of the cap. The large bevel effectively increases an acceptance aperture for installing the cap into the opening in the fiber-optic connector.

[0044] One example of a dust cap for a fiber-optic connector is shown in FIGS. 5A-5C. Exemplary dimensions are shown for a cap suitable for use with LC fiber-optic connectors. Approximate dimensions are given in millimeters. Other sizes and designs suitable for other fiber-optic connectors are contemplated by the inventors as being within the scope of the invention.

[0045] A cap as described herein may be used as part of a fiber-optic connector comprising an optical ferrule containing an optical fiber, wherein the optical ferrule extends from an opening in a housing 320 of the fiber-optic connector 300. A removable cap 200may cover an end of the optical ferrule 310, e.g., as depicted in FIG. 3. (Only a portion of the fiber-optic connector 300 is shown.) The removable cap may comprise a first portion 210 comprising a wall 208 around an inner cavity 205 and longitudinal ribs 220 on an outer surface of the wall. The first portion may have a first outer dimension transverse to the longitudinal ribs, and the longitudinal ribs may contact a first surface of the opening in the connector housing 320.

[0046] Also contemplated are methods associated with installing a dust cap 200 over an optical ferrule of a fiber-optic connector. A method for covering an optical ferrule 310 that extends from an opening in a housing 320 of a fiber-optic connector 300 may comprise an act of installing, into the opening and over an end of the optical ferrule 310, a cap 200 comprising a first portion 210 having a wall 208 extending around an inner cavity 205 and longitudinal ribs 220 on an outer surface of the wall. The method may include installing the cap such that herein the longitudinal ribs contact a first surface of the housing. The ribs may deform when in contact with the first surface of the housing. The method may further include an act of moving the cap until a stopping feature, e.g., step 240 or end 215, in the cap contacts a second surface of the housing. The stopping feature may prevent the cap 200 from contacting an end of the optical ferrule. In various embodiments, the longitudinal ribs, which may be deformed and in contact with the housing 320, retain the cap within the opening by friction. According to some embodiments, the stopping feature comprises a step 240 that extends around a perimeter of the cap and includes a sealing surface facing the housing 320. The act of moving the cap may further comprise contacting the sealing surface to the second surface of the housing to form a sealed enclosure over the optical ferrule 310.

[0047] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described in any way.

[0048] While the present teachings have been described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. On the contrary, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those of skill in the art.

[0049] The claims should not be read as limited to the described order or elements unless stated to that effect. It should be understood that various changes in form and detail may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims. All embodiments that come within the spirit and scope of the following claims and equivalents thereto are claimed.

Claims

CLAIMS What is claimed is:

1. A cap for a fiber-optic connector of the type having an optical ferrule in an opening of a housing, the cap comprising:

a first portion comprising a wall around an inner cavity and longitudinal ribs on an outer surface of the wall, the first portion having a first outer dimension transverse to the longitudinal ribs; and

a second portion connected to the first portion,

wherein the inner cavity is sized to accommodate an outer dimension of the optical ferrule, and wherein the cap is configured to be installed in the opening over an end of the optical ferrule.

2. The cap of claim 1, wherein a first end of the inner cavity is open at a first end of the cap to accept the optical ferrule and a second end of the cavity is closed within the cap.

3. The cap of claim 1, wherein the cap is a unitary structure formed from a same material.

4. The cap of claim 1, wherein the longitudinal ribs are more compliant than the second portion.

5. The cap of claim 1, wherein the Shore A hardness of the longitudinal ribs is between 60 and 100.

6. The cap of claim 1, wherein at least the longitudinal ribs are formed from a thermoplastic elastomer.

7. The cap of claim 6, wherein the Shore A hardness of the longitudinal ribs is between 80 and 95.

8. The cap of claim 6, wherein the longitudinal ribs are beveled.

9. The cap of claim 6, wherein the first portion includes a bevel.

10. The cap of claim 6, wherein the first outer dimension is equal to or greater than an inner dimension of the opening in the housing.

11. The cap of claim 10, wherein the fiber-optic connector is a type LC connector.

12. The cap of claim 10, wherein the first portion is cylindrical.

13. The cap of claim 10, wherein the second portion includes a second outer dimension greater than the first outer dimension.

14. The cap of claim 10, wherein the second portion includes a varied outer surface at a second end of the cap for improving a grasp of the second end of the cap.

15. The cap of claim 10, wherein the second portion comprises a step to a second outer dimension greater than the first outer dimension, wherein the step extends around a perimeter of the cap.

16. The cap of claim 15, wherein the step includes a sealing surface configured to contact a surface of the housing when the cap is installed in the opening over the end of the optical ferrule so as to form a sealed enclosure around the optical ferrule.

17. A fiber-optic connector, comprising:

an optical ferrule containing an optical fiber, wherein the optical ferrule extends from an opening in a housing of the fiber-optic connector; and

a removable cap covering an end of the optical ferrule, the removable cap comprising a first portion comprising a wall around an inner cavity and longitudinal ribs on an outer surface of the wall, wherein the first portion has a first outer dimension transverse to the longitudinal ribs and the longitudinal ribs contact a first surface of the opening of the housing.

18. The fiber-optic connector of claim 17, wherein the removable cap does not contact the optical ferrule when installed in the opening over the end of the optical ferrule.

19. The fiber-optic connector of claim 17, wherein the longitudinal ribs are formed from a compliant material that deforms when the removable cap is installed in the opening over the end of the optical ferrule.

20. The fiber-optic connector of claim 17, wherein the fiber-optic connector is a type LC connector.

21. The fiber-optic connector of claim 17, wherein an inner surface of the removable cap defining the inner cavity is between 0.25 millimeter and 3 millimeters from a surface of the optical ferrule when the removable cap is installed in the opening over the end of the optical ferrule.

22. The fiber-optic connector of claim 17, wherein the removable cap further comprises a second portion connected to the first portion, the second portion including a second outer dimension greater than the first outer dimension.

23. The fiber-optic connector of claim 22, wherein the removable cap further comprises a step between the first portion and second portion, the step extending around a perimeter of the removable cap and including a surface facing the fiber-optic connector.

24. The fiber-optic connector of claim 23, wherein the step engages a surface of the housing to form a sealed enclosure when the cap is installed in the opening over the end of the optical ferrule.

25. The fiber-optic connector of claim 23, wherein the step prevents the removable cap from contacting the end of the optical ferrule when the cap is installed in the opening over the end of the optical ferrule.

26. The fiber-optic connector of claim 23, wherein at least an end of the removable cap prevents the removable cap from contacting the end of the optical ferrule when the cap is installed in the opening over the end of the optical ferrule.

27. A method for covering an optical ferrule that extends from an opening in a housing of a fiber-optic connector, the method comprising:

installing into the opening and over an end of the optical ferrule a cap comprising a first portion having a wall extending around an inner cavity and longitudinal ribs on an outer surface of the wall, wherein the cap is installed such that the longitudinal ribs contact a first surface of the housing; and

moving the cap until a stopping feature in the cap contacts a second surface of the housing.

28. The method of claim 27, wherein the longitudinal ribs are compliant and deform when in contact with the first surface and retain the cap within the opening by friction when the cap is installed over the end of the optical ferrule.

29. The method of claim 27, wherein at least the longitudinal ribs are formed from a material having a Shore A hardness between 80 and 95.

30. The method of claim 27, wherein the stopping feature comprises a step that extends around a perimeter of the cap and includes a sealing surface facing the housing, and wherein the moving comprises contacting the sealing surface to the second surface of the housing to form a sealed enclosure over the optical ferrule.

31. The method of claim 30, wherein the sealing surface comprises a compliant rim.

32. The method of claim 27, wherein the stopping feature prevents the cap from contacting the end of the optical ferrule.