1. Field of the Disclosure
The technology of the disclosure relates to securing optical fibers in ferrules as part of fiber optic connector assemblies used to establish fiber optic connections.
2. Technical Background
Benefits of optical fibers include extremely wide bandwidth and low noise operation. In cases where high bandwidth is required between two interconnection locations, fiber optic cables having fiber optic connectors may be used to communicate information between these locations. The fiber optic connectors also may be used to conveniently connect and disconnect the fiber optic cables from the interconnect locations when maintenance and upgrades occur.
Each of the fiber optic connectors may include a ferrule assembly having a ferrule. The ferrule has several purposes. The ferrule includes an internal pathway, called a ferrule bore, through which an optical fiber is supported and protected. The ferrule bore also includes an opening at an end face of the ferrule. The opening is where an optical surface of an end portion of the optical fiber may be located to be aligned to an end portion of another optical fiber of a complementary connector. The end portions need to be aligned to establish an optical connection.
The optical surface of the optical fiber is designed for a fixed spatial relationship to the end face of the ferrule. The optical surface facilitates light transmission and/or reception to and from the fiber optic cable. Efficient and accurate transmitting and receiving light between the optical surfaces of adjacent optical fibers of the fiber optic connector and the complementary fiber optic connector, respectively, is critical to minimize signal attenuation. In this regard, the optical fiber should not move relative to the ferrule or the spatial relationship of the optical surface of the optical fiber from the end face of the ferrule would not be precisely located. Precision is required, because the optical fiber extends from the end face of the ferrule towards another optical surface of the optical fiber of the complementary optical connector. When the spatial relationship is precisely achieved, the optical surface of the optical fiber will exactly press against the optical surface of the other optical fiber of the complementary fiber optic connector to minimize the air gap therebetween, for example, consistent with International Standard CEI/IEC 61755-3-2. Air gaps between the optical surfaces can increase attenuation.
In this regard, a thermosetting epoxy (“epoxy”) is typically utilized to bond the optical fiber to the ferrule bore, so the optical fiber is secured within the ferrule bore. Epoxy may be less desirable because of fundamental mechanical properties, an inefficient and difficult application process, and significant manufacturing waste. The fundamental mechanical properties of epoxy cause problems for fiber optic connector performance. The ferrule and the optical fiber bond may be required to function consistently over tens of thousands of cycles of optical connections and disconnections with complementary optical connectors as networks are upgraded and maintained over the life of the optical connector. The mechanical properties of epoxy are plastic wherein the optical fiber generally increasingly moves over time when subjected to mechanical and thermal loading. The spatial relationship of the optical fiber within the ferrule is difficult to predict with certainty, because epoxy is difficult to apply uniformly to all ferrule assemblies.
Applying epoxy during manufacturing can be inefficient and difficult. The epoxy may be incorrectly applied to the ferrule and optical fiber during manufacturing. Specifically, epoxy is typically applied within the ferrule manually through a syringe. The epoxy flows from the syringe and is difficult to direct to the designated location between the ferrule and the optical fiber. An incomplete bond may be formed between the optical fiber and the ferrule when not enough epoxy flows to the designated location. The incomplete bond may allow movement to occur and thereby change the spatial relationship between the optical fiber and the ferrule and cause attenuation. Epoxy may also inadvertently flow from the syringe to other areas of the fiber optic connector causing defects. For example, the epoxy may flow to a spring connected to a ferrule holder body which needs to move within an inner housing unfettered by epoxy. A relatively expensive epoxy-resistant part, for example, a Teflon lead-in tube, is added to the fiber optic connectors to contain the epoxy and prevent epoxy flow to other areas of the fiber optic connector. Epoxy may also develop air bubbles or voids and so the ferrule and optical fiber may need to be placed in a time-consuming vacuum environment to remove these voids or air bubbles. To detect defects related from epoxy, labor-intensive inspection procedures can be conducted as part of the manufacturing process. The numerous additional manufacturing steps needed to support the application of epoxy to the ferrule make the manufacture of a ferrule assembly inefficient.
Also, applying epoxy as part of assembling a ferrule assembly may create significant manufacturing waste. Epoxy is made up of an epoxide resin (“resin”) and a polyamine hardener (“hardener”). The resin and hardener are mixed together before being introduced into the ferrule. Shipments of resin and hardener often arrive at the assembly area at irregular frequencies and may have a shelf life of six (6) months to a year. As an example, characteristics of the epoxy change during the six (6) months and so unused epoxy is discarded after a six (6) month period has elapsed, causing in some cases significant manufacturing waste. Further, once mixed, the epoxy must be used within a time window or discarded causing even further waste. The time window may be generally only extended to, for example, up to eight (8) hours when the mixed epoxy is chilled.
A process and assembly are desired to secure the optical fiber from moving with respect to the ferrule that is more efficient to manufacture and creates less waste.
Embodiments disclosed herein include ferrule assemblies employing mechanical interfaces for optical fibers and related component and methods. The ferrule assemblies may be used in fiber optic connectors to precisely position the optical fiber relative to the ferrule to facilitate an optical connection with another optical device. In certain embodiments disclosed herein, the ferrule assemblies include a ferrule that includes an inner surface forming a ferrule bore. Each of the ferrules also includes an end portion of an optical fiber disposed in the ferrule bore. The inner surface of the ferrule bore abuts against an outer surface of the optical fiber to form a mechanical interface. In this manner, the mechanical interface secures the optical fiber within the ferrule bore and precisely positions the optical fiber relative to the ferrule. This mechanical interface may eliminate the need for epoxy or other means to secure the optical fiber within the ferrule bore.
In another embodiment, a method of assembling a ferrule assembly for a fiber optic connector is provided. The method includes providing a ferrule including an inner surface forming a ferrule bore. The method also includes disposing an end portion of the optical fiber in the ferrule bore. The method also includes forming a mechanical interface by abutting the inner surface of the ferrule bore against an outer surface of the optical fiber. The mechanical interface secures the end portion of the optical fiber within the ferrule bore. In this manner, the optical fiber is secured within the ferrule bore and thereby precisely positioned relative to the ferrule.
Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments as described herein, including the detailed description that follows, the claims, as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an overview or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed.
Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all embodiments are shown. Indeed, the concepts may be embodied in many different forms and should not be construed as limiting herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.
Embodiments disclosed herein include ferrule assemblies employing mechanical interfaces for optical fibers and related component and methods. The ferrule assemblies may be used in fiber optic connectors to precisely position the optical fiber relative to the ferrule to facilitate an optical connection with another optical device. In certain embodiments disclosed herein, the ferrule assemblies include a ferrule that includes an inner surface forming a ferrule bore. Each of the ferrules also includes an end portion of an optical fiber disposed in the ferrule bore. The inner surface of the ferrule bore abuts against an outer surface of the optical fiber to form a mechanical interface. In this manner, the mechanical interface secures the optical fiber within the ferrule bore and precisely positioned relative to the ferrule. This mechanical interface may eliminate the need for epoxy or other means to secure the optical fiber within the ferrule bore.
In this regard,
The ferrule 16(1) includes an inner surface 27 forming the ferrule bore 26 and connecting the first end 22 of the ferrule 16(1) to the second end 24. The end portion 18 of the optical fiber 12 is disposed in the ferrule bore 26 and extends to the end face 20 on the second end 24 of the ferrule 16(1). An opening 29 of the end face 20 of the ferrule 16(1) may enable the optical fiber 12 to exit the ferrule bore 26 and extend through the end face 20 so that the end portion 18 of the optical fiber 12 may be located at the end face 20 of the ferrule 16(1) for convenient optical coupling with the complementary receptacle. An optical axis A1 may be disposed through a center of the ferrule bore 26.
The optical axis A1 extends from the first end 22 to the second end 24 of the ferrule 16(1). The optical axis A1 may coincide with the ferrule bore 26, because the optical fiber 12 may be received through the ferrule bore 26.
The optical fiber 12 is secured within the ferrule bore 26 with a mechanical interface 30 in this embodiment as opposed to use of epoxy as a non-limiting embodiment. The inner surface 27 of the ferrule bore 26 may abut against an outer surface 31 of the optical fiber 12 to form the mechanical interface 30. The mechanical interface 30 secures the optical fiber 12 within the ferrule bore 26. The mechanical interface 30 may be free from a bonding agent, for example, epoxy. In this manner, no epoxy may be disposed between the inner surface 27 of the ferrule bore 26 and the outer surface 31 of the optical fiber 12. The mechanical interface 30 may prevent movement of the optical fiber 12 within the ferrule bore 26 to minimize signal attenuation between the optical fiber 12 and the complementary receptacle (not shown), which may include an opposing optical fiber.
As will be discussed by example in more detail below, the mechanical interface 30 may be configured to allow the optical fiber 12 to enter or depart the ferrule bore 26 when a temperature of the ferrule 16(1) is at least a threshold temperature, for example, one-hundred (100) degrees Celsius. The mechanical interface 30 may be a thermal clamp operated by changes in temperature of the ferrule 16(1) which changes dimensions of the inner surface 27 of the ferrule bore 26 relative to the outer surface 31 of the optical fiber 12. A thermal expansion coefficient of the ferrule 16(1) may be at least fifteen (15) times as large as a thermal expansion coefficient of the optical fiber 12. In this manner, a minimum bore width WB1 (
With continuing reference to
With continuing reference to
An entry opening 32 may be disposed at the first end 22 of the ferrule 16(1). The entry opening 32 may provide the passageway by which the optical fiber 12 enters the ferrule bore 26 of the ferrule 16(1). The entry opening 32 may be cone-shaped to provide easy entry of the optical fiber 12 into the ferrule bore 26.
With continuing reference to
It is noted that the ferrule holder body 36 in
The ferrule 16(1) includes more features than can be observed in
With reference back to
The optical fiber 12 includes more features than can be observed in
The optical fiber 12 may include a bare optical fiber 58 and a primary coating 60. The primary coating 60 may surround the bare optical fiber 58 and may prevent surface abrasions from forming on the bare optical fiber 58 during manufacturing and while in the fiber optic connector 10. Surface abrasions may be created when the bare optical fiber 58 contacts other objects. The surface abrasions may weaken the bare optical fibers 58 and thereby damage or break the bare optical fibers 58. The primary coating 60 prevents surface abrasions from being created and thereby protect the bare optical fiber 58. The primary coating 60 may comprise a strong flexible material, for example, ultra-violet (UV) curable acrylate.
The outer jacket 56 of the fiber optic cable 54 may be partially stripped from the end portion 18 up to a transition interface 62, as shown in
With reference back to
Details of the fiber optic connector 10 have been introduced employing the ferrule 16(1) having the end portion 18 of the optical fiber extending through the end face 20 of the ferrule 16(1). The relationship of the ferrule 16(1) to the insertion of the optical fiber 12 into the ferrule 16(1) and ferrule holder body 36 will now be discussed in relation to a fiber optic connector 10. In this regard, the fiber optic connector 10 may form the final critical passageway travelled by the end portion 18 of the optical fiber 12 to the end face 20. The ferrule holder body 36 may comprise a front end 72 opposite a rear end 74 along the optical axis A1. The ferrule holder body 36 may include an internal passage 76 formed by an inner body surface 78 extending from the front end 72 to the rear end 74 along the optical axis A1 to thereby align the end portion 18 of the optical fiber 12 to the ferrule bore 26. The lead-in tube 50 may include a front end 80 integrated with the rear end 74 of the ferrule holder body 36. The lead-in tube 50 may include a lead-in bore 82 extending in the optical axis A1 from a rear end 84 of the lead-in tube 50 to the front end 80 of the lead-in tube 50. An inner lead-in surface 86 may form the lead-in bore 82 of the lead-in tube 50. The inner lead-in surface 86 may guide the optical fiber 12 thorough the lead-in bore 82 and into the internal passage 76 of the ferrule holder body 36.
The lead-in tube 50 may be made of a flexible and resilient material with high surface lubricity, for example, polyethylene, silicone, or thermoplastic elastomer. This material may also include additives, for example, mineral fill or silica-based lubricant or graphite. In this manner, the optical fiber 12 may smoothly travel the lead-in bore 82 without being caught during insertion.
The ferrule holder body 36 may be made of a relatively strong material, for example, metal or plastic. The ferrule holder body 36 may be made with all junctions and edges of the internal passage 76 chamfered or otherwise smoothly transitioned from one inside diameter to the next to provide surfaces to the optical fiber 12 without sharp edges for the optical fiber 12 to catch or be damaged during insertion.
The front end 80 of the lead-in tube 50 may be configured to receive and guide the end portion 18 of the optical fiber 12 along the optical axis A1 through the rear end 74 of the ferrule holder body 36 and into the internal passage 76 of the ferrule holder body 36. The lead-in bore 82 of the lead-in tube 50 and the internal passage 76 of the ferrule holder body 36 enables the end portion 18 of the optical fiber 12 to reach the first end 22 of the ferrule 16(1) with a protected and aligned position before continuing through the ferrule bore 26 to the end face 20. The end portion 18 of the optical fiber 12 may exit the ferrule bore 26 through the opening 29 after traveling from the first end 22 to the second end 24 of the ferrule 16(1). After exiting the opening 29, the end portion 18 may extend a height H1 past the end face 20 of the ferrule 16(1). The optical fiber 12 may then be secured by the mechanical interface 30. The height H1 may be, for example, more than five-hundred (500) nanometers (nm) and may be further reduced with material removal operations, for example polishing, to form the optical surface 14 of the end portion 18 of the optical fiber 12.
The optical surface 14 of the optical fiber 12 is disposed at a position relative to the end face 20 of the ferrule 16(1) to provide a pathway for optical transmission and/or reception. Efficient and accurate transmitting and receiving of light between the optical surfaces 14 of the adjacent optical fibers 12 of the fiber optic connector 10 and the complementary receptacle, respectively, may be critical to minimize signal attenuation. In this regard, the optical surface 14 of the optical fiber 12 should be created to be free of optical defects. Secondly, the position of the optical surface 14 of the optical fiber 12 relative to the end face 20 of the ferrule 16(1) may be accurately achieved and secured by the mechanical interface 30. Accuracy of the position is required, because the optical fiber 12 extends from the ferrule bore 26 of the ferrule 16(1) to exactly press against the optical surface 14′ of the other optical fiber 12′ of the complementary receptacle during an optical connection to minimize the air gap therebetween, for example, consistent with International Standard CEI/IEC 61755-3-2. Air gaps between the optical surfaces causes attenuation and should be avoided; thus keeping the optical fiber 12 secure within the ferrule 16(1) with the mechanical interface 30 may reduce air gaps.
Now that the ferrule assembly 15 has been introduced, exemplary processes 90(1)-90(3) will be introduced in succession for inserting the optical fiber 12 within the ferrule bore 26 as part of assembling the ferrule assembly 15. The ferrule assembly 15 employs the mechanical interface 30 for the optical fiber 12. In this regard,
As shown in
As depicted in
In this regard,
Now that the processes 90(1)-90(3) have been discussed to assemble the ferrule assemblies 15(1)-15(3) for the fiber optic connector 10, ferrule assemblies 15(4)-15(6) are now introduced including ferrules 16(4)-16(5), respectively. The ferrule assemblies 15(4)-15(6) are compatible with the processes 90(1)-90(3) and the mechanical interface 30 to secure the end portion 18 of the optical fiber 12 within the ferrule bore 26. The details of the ferrule bore 26 facilitating the mechanical interface 30 will now be discussed.
In this regard,
Moreover, the tapered shape of the entry cone 106 may also provide space for the silicone 111 to be disposed in the first end 22 of the ferrule 16(4) between the ferrule 16(4) and the optical fiber 12. The silicone 111 may protect the optical fiber 12 from sharp bends which may damage the optical fiber 12. The mechanical interface 30 may still provide sufficient force FI to secure the optical fiber 12 within the ferrule 16(4) in the presence of the silicone 111.
In a different example,
Moreover, the ferrule 16(5) may further include a second bore transition interface 113 between the second end 24 of the ferrule 16(5) and the first bore transition interface 108. The first portion 110 of the inner surface 27 may include an exit portion 114 and a second portion 112. The second bore transition interface 113 may attach the exit portion 114 to the second portion 112. The exit portion 114 comprises a uniform or substantially uniform width from the second end 24 of the ferrule 16(5) to the second bore transition interface 113. The second portion 112 may comprise a uniform or substantially uniform width from the second bore transition interface 113 to the entry cone 106. The uniform or substantially uniform width W2 of the second portion 112 may be greater than the uniform or substantially uniform width W3 of the exit portion 114 to thereby increase the force FI closer to the end face 20 of the ferrule 16(5). The increased force FI may thereby better secure the optical fiber 12 adjacent to the end face 20.
In a different example,
Moreover, the ferrule 16(6) may further include the second bore transition interface 113 between the second end 24 of the ferrule 16(6) and the first bore transition interface 108. The first portion 110 of the inner surface 27 may include the exit portion 114 and a third portion 116. The second bore transition interface 113 may attach the exit portion 114 to the third portion 116. The exit portion 114 may comprise the uniform or substantially uniform width from the second end 24 of the ferrule 16(6) to the second bore transition interface 113. The third portion 116 may comprise a second tapered shape from the second bore transition interface 113 to the entry cone 106. The second tapered shape includes a smaller width change than the first tapered shape. The second tapered shape of the third portion 116 allows a gradual increase in the force FI to provide gradual support for the optical fiber 12 along the optical axis A1 towards the end face 20 of the ferrule 16(6). In this regard,
As used herein, it is intended that terms “fiber optic cables” and/or “optical fibers” include all types of single mode and multi-mode light waveguides, including one or more optical fibers that may be upcoated, colored, buffered, ribbonized and/or have other organizing or protective structure in a cable such as one or more tubes, strength members, jackets or the like. The optical fibers disclosed herein can be single mode or multi-mode optical fibers. Likewise, other types of suitable optical fibers include bend-insensitive optical fibers, or any other expedient of a medium for transmitting light signals. Non-limiting examples of bend-insensitive, or bend resistant, optical fibers are ClearCurve® Multimode or single-mode fibers commercially available from Corning Incorporated. Suitable fibers of these types are disclosed, for example, in U.S. Patent Application Publication Nos. 2008/0166094 and 2009/0169163, the disclosures of which are incorporated herein by reference in their entireties.
Many modifications and other embodiments of the embodiments set forth herein will come to mind to one skilled in the art to which the embodiments pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, the optical fiber 12 may be cooled or heated while the ferrule 16 is heated to the threshold temperature. Also, for simplicity the processes 90(1)-90(3) and associated
Therefore, it is to be understood that the description and claims are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. It is intended that the embodiments cover the modifications and variations of the embodiments provided they come within the scope of the appended claims and their equivalents. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/663,199 filed on Jun. 22, 2012, the content of which is relied upon and incorporated herein by reference in its entirety.
Number | Date | Country | |
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61663199 | Jun 2012 | US |