Patent Application
20230152522
The present subject matter, in general, is directed to an optic fiber stub portion and, more particularly, is directed to a re-spliceable splice-on connector.
An optic fiber is a flexible and transparent fiber manufactured by drawing glass or plastic to a diameter slightly more than the diameter of a strand of human hair. [See “Optical Fiber,” The Fiber Optic Association.] Optic fibers, able to transmit light between end portions of optic fiber, are used in fiber-optic communications, as fibers permit data transmission over greater distances and at higher bandwidths (“higher data transfer rates”) than electrical cables. [“Optical Fiber,” cited above.]
Optic fibers are used instead of metal wires since signals travel along optic fibers with less flux intensity loss through them. [Optical Fiber Communications: Principles and Practice, by Senior, John M; and Jamro, M. Yousif (2009), Pearson education, pp. 7-9.] Also, optic fibers are immune to electromagnetic interference, a problem experienced when using metal wires. [Optical Fiber Communications.]
In addition, optic fibers have a core covered by a transparent cladding material which has a lower index of refraction. [Optical Fiber Communications.] Light is kept in the core by the phenomenon of total internal reflection, thus causing the fiber to function as a waveguide. [Optical Fiber Communications, pages 12-14.]
Joining optic fibers with low loss is important in optic fiber communication. [Optical Fiber Communications, page 218.] Joining optic fibers, more complex than joining electrical wires or cables, involves careful cleaving of the optic fibers, precise alignment of fiber cores, and the precise coupling of resulting-aligned cores. [Optical Fiber Communications.] For applications requiring permanent connections, a fusion splicer is typically used. Employing a fusion splicer technique, an electric arc is used to melt two optic fiber ends together. [Optical Fiber Communications.]
Certain terms which I shall use throughout this patent application shall now be noted and defined as follows. The term “connector” shall be understood to refer to an optic fiber connector having four basic components: a ferrule; a connector body; a cable; and a coupling device. The term “fiber stub” shall be understood to refer to a length or piece of optic fiber, ordinarily very short in length, that extends from the back of a connector. The term “fiber stub length” shall be understood to refer to length, which will vary and can be about 125 mm, a preferred length for the present subject matter, for optic fiber extending from the back of a connector.
The term “fusion splicer” shall be understood to refer to a machine using an electric arc to melt two optic fibers together at cleaved end faces to form fused optic fiber. A resulting fusion splice permanently joins two optic fibers end-to-end, enabling light signals to pass from one end to the other with little loss. The splicer precisely adjusts, automatically in modern devices, light-guiding cores at the ends of the fibers to be spliced. The term “cable holder” refers to a device that positions or holds optic fiber cable in a splicer. Cable holders differ based on optic fiber diameter, with the most popular cable holders being designed for 250 µm, 900 µm, 2 mm, and 3 mm diameter cables, and 12-fiber “ribbon cable” consisting of twelve individual 250 µm diameter cables bonded together as a single cable. A “cable” consists of a core, cladding, buffer, and jacket. (See Wikipedia for such cable layers.)
The term “connector holder” shall be understood to refer to a device that holds and properly positions the connectors in a fusion splicer for splicing. The term “rubber boot” shall be understood to refer to an elongated (hollow) silicone rubber material, sized and shaped to cover and protect the splice area of the optic fiber. The rubber boot also connects to the connector, and thereby provides strain relief. The term “rubber boot length” shall be understood to refer to the total length of the rubber boot. The term “strain relief,” essential to preserve the mechanical and electrical integrity and overall performance of spliced optic fiber cables, shall be understood to refer to relief of stress and tension, in an optic fiber, that could cause damage to the fiber cable or the connection between the connector and the cable.
The term “FC” shall be understood to refer to an optic fiber cable connector using a threaded plug and socket. For bi-directional transmission, two optic fiber cables and two FC connectors are used. The term “SC,” an acronym for a standard connector and/or a subscriber connector, shall be understood to refer to an optic fiber cable connector using a push-pull latching mechanism resembling common audio and video cables. For bi-directional transmission, two optic fiber cables and two SC connectors (aka dual SC) are used. The term “LC,” an acronym for Lucent connector, shall be understood to refer to a miniature version of an optic fiber SC connector. While an LC connector resembles an SC connector, with an LC connector being half the size, an LC connector thus has a 1.25 mm ferrule instead of a 2.5 mm ferrule. The term “ST,” also referred to as a straight tip connector, the original de facto “standard” connector for commercial optic fiber cable wiring needs, shall be understood to refer to an optic fiber cable connector having a bayonet plug and a socket. Bi-directional transmission requires two fiber cables and two ST connectors.
The term “MPO” refers to an industry acronym for a “multi-fiber push on” connector, used by technicians and persons of ordinary skill in this field. The MPO connector was developed to provide multi-fiber connectivity in a single connector to support high bandwidth and high data density applications. While present fiber counts for MPO connectors are 12 and 24 optic fibers per connector, fusion splicers presently commercially available can only splice 12-fiber count MPO connectors.
The term “MTP,” also used by technicians and persons of ordinary skill in this field, shall be understood to refer to an assortment of high-performance MPO connectors with special enhancements engineered to provide MTP connectors with optical and/or mechanical performance improvements in comparison to ordinary MPO connectors. In 1996, “MTP” a federally registered trademark owned by US Conec and used in relation to a family of advanced MPO connectors designed for 4-, 8-, and 12-fiber ribbon applications, was released to the US market. In that same year, the International Electrotechnical Commission standardized this MPO format.
As a result, there are five types of optic fiber connectors: FC (single fiber); LC (single fiber); SC (single fiber); ST (single fiber); and MPO/MTP (12 or more fibers)
Current attempts to permanently join two optic fibers end-to-end, enabling optical light signals to pass from one optic fiber to another with minimal loss, will occasionally result in a “failure.” Such failure may occur when an optic fiber end portion is poorly cleaved by a cleaving mechanism; may occur when an optic fiber end portion has a crack in it; may occur when an optic fiber end portion is dirty; may occur when a fusion splicer over-arcs by accident and damages an optic fiber end portion; may occur when a given length of optic fiber is not properly arranged in the grooves of a cable splicer; or may occur when a portion of the length of optic fiber has a bend in it and a fusion splicer camera cannot focus upon the optic fiber.
However, using a fusion splicer to re-join optic fiber end portions resulting from such failure is currently impractical, based on current fiber-joining techniques.
Since I did not find a commercial product that addresses the failure problem noted and enables a fusion splicer easily to re-join optic fiber end portions resulting from such failures, I reviewed US patents and published applications for a solution.
U.S. Pat. 4,728,170 to Robertson discloses a process whereby a single mode optical fiber preset attenuator is made by forming a fusion splice between a length of silica fiber possessing no internal waveguiding structure to a length of single mode optical fiber, then cutting the silica fiber to a predetermined length to form a short stub that is next fusion-spliced to a second length of single mode fiber. U.S. Pat. 5,993,071 to Hultermans discloses an adapter that is used to connect a first optical fiber connector to a second optical fiber connector. The adapter makes it possible for optical fiber connectors with perpendicular and inclined end faces to be interconnected or connected to a corresponding different optical fiber system.
U.S. Pat. 6,805,491 and 6,955,478, both to Durrant et al., are directed to a device which includes a stub and an optical fiber. The stub has an aperture and includes a first end and a second end. The optical fiber, located in the aperture, has a first end and a second end. The first end of the optical fiber is polished, so as to be flush with the first end of the stub. The second end of the optical fiber is cleaved at a predetermined position, so as to provide for a predetermined length of the optical fiber measured from the first end to the second end of the optical fiber.
U.S. Pat. 7,178,990 to Cavey et al. is directed to a fiber optic stub fiber connector used for reversibly and nondestructively terminating an inserted field fiber having a buffer over a portion of it. The connector includes a housing and a ferrule including a stub fiber disposed within and extending from a bore through the ferrule. The ferrule is partially disposed within and supported by the housing. The connector further includes a reversible actuator adapted to reversibly and nondestructively terminate the inserted field fiber to the stub fiber. The reversible actuator includes a buffer clamp for engaging with the buffer to simultaneously provide reversible and nondestructive strain relief to the terminated field fiber.
U.S. Pat. 7,186,035 to Dunn et al. is directed to an optical fiber connector having a receptacle or socket which includes a recessed optical fiber ferrule assembly for aligning an optical fiber within the connector. Recessed within the socket is a sleeve for receiving and bringing into optical alignment the optical fiber ferrule assembly, located at an internal end of the socket, with a similar optical fiber ferrule assembly of an optical plug which is connected to the optical socket.
U.S. Pat. 7,261,473 to Owen et al. discloses an optical sub assembly that provides electrical isolation between a receptacle having a nose for receiving an optical fiber and a package housing an optical device. The nose houses a ferrule containing a fiber stub optically aligned with an optical device housed in a package before securing the receptacle to the package. The electrical insulation is provided between the nose and the package by a sleeve extending along a middle portion of the ferrule and an insulating portion located between the sleeve and the nose.
U.S. Pat.7,956,992 to Watt et al. is directed to a method for testing optical fiber connection quality of an optical drop fiber between a telecommunications system and a subscriber connection box in a multi-dwelling unit or other subscriber premises before connection to other subscriber equipment. An end portion of an optical fiber to-be-tested is placed in a fiber-holding device. The fiber-holding device holds the fiber end portion in alignment with a suitable reflective body. An optical signal is provided from the system direction which is reflected by the reflective body back towards the system. The reflected signal is detected by a suitable instrument, such as an optical time domain reflectometer, to confirm acceptable signal quality of the optical path between the system and the fiber end.
U.S. Pat. 8,556,521 to Everett et al. is directed to an optical connector for use in a fiber optic communications system, and to an expanded beam optical connector for connecting optical fibers. The connector comprises a housing, a port for receiving an optical fiber end, a cylindrical ferrule within the housing having opposite first and second ends, and an optical fiber stub held within the ferrule and extending between the ferrule ends. A sleeve surrounding the ferrule extends towards the port away from the second ferrule end to present an open end to the sleeve for receiving a termination ferrule of an optical fiber inserted into the port.
U.S. Pat. 9,557,492 and 9,897,770, both to Park et al., are directed to a hybrid optical fiber stub device comprising a first ferrule transparent to UV light and a second ferrule. An optical fiber is disposed through the first and second ferrules. The input and output faces of the optical fiber, when properly prepared, are suitable for optical coupling. A photonic device is coupled to the first optical fiber surface. A UV-curable epoxy is disposed between the photonic device and the first optical fiber surface. The UV-curable epoxy has an index of refraction that ranges from an index of refraction of the first optical fiber to an index of refraction of the photonic device. A second optical fiber is coupled to the first optical fiber.
U.S. Pat. 10,345,536 to Shao et al. is directed to an optical fiber connector, comprising: a housing, a ferrule within the housing; an end sleeve connected to a rear end of the housing; and an optical cable clamp inserted within the end sleeve. The clamp is provided for the purpose of clamping an optical cable. The optical cable is secured within the optical cable clamp. The optical cable clamp is inserted and secured within the end sleeve. The optical fiber of the optical cable is inserted within the housing and butt-joined with the embedded optical fiber in the ferrule.
U.S. Pat. 10,473,859 to Chabot et al. is directed to fiber optic connector comprising a fusion assembly for strengthening a splice point. The fusion assembly comprises an elongate mechanical support positioned adjacent the splice point and snugly encased by a flexible tube. A meltable adhesive in the form of a hollow tube is positioned over the splice point and the flexible tube comprises a heat shrinkable material. The elongate mechanical support comprises an elongate plate having a concave surface positioned adjacent the splice point and a C-shaped cross section.
U.S. Pat. US 10,761,277 to Durrant is directed to a vent or slot, which is provided between the ferrule and the stub body, for enabling gases generated from a low melting glass sealing process of an optical fiber to the ferrule stub to escape.
U.S. published application 2013/0004128 to Zhang discloses a device that enables a physical contact fiber optic connector into an expanded beam connector. The device includes a fiber stub, an aspherical lens, and a housing. The fiber stub includes a stub body and a predetermined length of optical fiber retained that is by the stub body. The housing retains the fiber stub and aspherical lens so that the length of optical fiber of the fiber stub is in optical communication with the lens.
U.S. published application 2021/0103097 to Wang is directed to a low-profile splice protection system for protecting multi-fiber fusion splice sites. The splice protection system includes coating material to package a splice site, and a housing.
However, these US patents and published applications do not provide solutions to problems occurring when an optic fiber end portion is poorly cleaved by a cleaving mechanism, when an optic fiber end portion is cracked, when an optic fiber end portion is dirty, when a fusion splicer accidentally over-arcs and damages an optic fiber end portion, when a given length of optic fiber is not properly arranged in grooves of a cable splicer, or when a portion of the length of optic fiber is bent and the fusion splicer camera, as a result, cannot focus upon the optic fiber.
To solve these problems, I increased optic fiber stub length extending from the connector by increasing a length of the associated rubber boot. One advantage of increasing the rubber boot length is that a longer optic fiber stub length eliminates a need for different connector holders relative to a fusion splicer. Connector holders are expensive and not universal to different types of connectors or fusion splicers. My design only requires a cable holder for an optic fiber stub, a simpler design. Another advantage is that a longer fiber stub length provides up to three opportunities to splice optic fiber ends correctly instead of the current single opportunity to splice correctly, thus saving money on “failed-splice” connections. Still another advantage of my solution to these problems is that an increased boot length better protects optic fiber within the boot, which improves fiber strain relief.
The elongated optic fiber stub portion of the present invention results from using an elongated hollow elastomeric tubular member, also known as a rubber boot, preferably made of silicone rubber, in connection with a method for fusing two end portions of optic fiber together. The method includes the following steps.
A first step involves passing an end of a first optic fiber having an insulation layer through the elongated tubular member and then through a heat-meltable sleeve. A second step involves stripping away the insulation layer from an end portion of the first optic fiber. A third step involves cleaning the insulation-stripped end portion with an effective amount of cleaning fluid and then cleaving an end face of the cleaned end portion of the optic fiber. A fourth step involves positioning the cleaved end face of the cleaned end portion of the first optic fiber in a fusion splicer. A fifth step involves stripping an insulation layer from an end portion of a second optic fiber. The second optic fiber includes an optic fiber connector that is attached to an end portion opposite the insulation-stripped end portion. A sixth step involves cleaning the second optic fiber end portion stripped of insulation with an effective amount of cleaning fluid and thereafter cleaving an end face of the cleaned end portion of the second optic fiber. A seventh step involves positioning the second optic fiber cleaved end portion in the fusion splicer closely adjacent, preferably abutting, the cleaved end portion of the second optic fiber. An eighth step involves fusing together the cleaved end faces of the first and second fibers.
A ninth step involves moving the sleeve made of meltable plastic over the fused-together end portions of the first and second optic fibers and then inserting the sleeved portion of the fused first and second fibers into an oven to melt the sleeve for the purpose of protecting the fused-together portions of the fibers. The elongated tubular member has opposite end portions; and one end portion of the elongated tubular member defines a tip. A tenth step involves sliding the hollow elongated tubular member over the sleeve-protected fused ends of the first and second optic fibers and attaching the end portion of the elongated tubular member that is located opposite the tip to the optic fiber connector. The elongated tubular member has a length effective for resulting in the sleeve-protected fused optic fibers disposed therein, to be cut near the tubular member tip, for producing an elongated optic fiber stub portion of the present subject matter. When the eighth step results in a failure to fuse abutting end faces of the first and second optic fibers, the second through eighth steps are repeated, and the ninth and tenth steps performed, whenever successful fusion of end faces of the two optic fibers occurs.
The patent or application file contains at least one drawing/screen shot executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.
Throughout the drawing figures and detailed description, I shall use similar reference numerals to refer to similar components of the present subject matter.
Step 1: Pass Optic Fiber End through an Elongated Boot and Plastic Sleeve. Please refer to
Step 2: Insert Optic Fiber into a Fiber Holder and then into Thermal Stripper.
Step 3: Clean Optic Fiber with Cleaning Fluid and Cleave in Precision Cleaver.
Steps 1-3 and figures associated with steps 1-3 represent preparation of an end face of the optic cable in accordance with the present subject matter, one advantage of which is a longer fiber stub length for the optic fiber, providing up to three opportunities to splice a connector correctly instead of the sole opportunity currently to splice optic fiber end faces correctly. Steps 4-8 that follow, and figures associated with steps 4-8, represent preparation of an end face of another optic fiber, to which the longer fiber stub end face can be joined up to three times if “failure” occurs, which results in reduced time and expense to correct such failure.
Step 4: Place Fiber Holder in Fusion Splicer; Then, Prepare Other Optic Fiber. Next, the technician is shown using his/her right hand RH to position the fiber holder 112 (now containing the freshly-cleaved end face of the optic fiber 104) within a fusion splicer 122. (Please refer to
Step 5: Next, Place Fiber Holder into Thermal Stripper to Strip Off Insulation. Next, the technician places the other fiber holder 206 (containing the connector pigtail assembly 200 -
Step 6: Remove Other Optic Cable From Stripper and Clean End Portion. After insulation which had been on the end portion 210 of the other optic fiber 202 has been stripped away by operation of the thermal stripper 116 (
Step 7: Put Clean End Portion in Cleaver; Put Fiber Holder into Fusion Splicer. Next, the other fiber holder 206, which I shall now refer to as the “second” fiber holder 206 (containing the connector pigtail assembly 200 with its freshly-cleaned and insulation-stripped end portion 210 of the second optic fiber 202), is inserted into the precision cleaver 120 (please refer to
Please note that the fusion splicer 122, at this time, also contains the fiber holder 112 (containing the cleaved end face of end portion 102 of optic fiber 104) that the technician inserted into fusion splicer 122 earlier. (
Also please note that the fusion splicer 122 includes an operational portion 126 (for fusing together the cleaved end faces of abutting optic fibers) and a cover portion 128 connected to the operational portion 126 by a hinged assembly that is unitary with both the operational portion 126 and the cover portion 128 (
Step 8: Close Cover of Splicer and Fuse End Faces of Optic Fibers Together. Next, the cover 128 is closed over the abutting end faces of the first and second optic fibers 104 and 202 (
Failure to Successfully Fuse Optic Fiber End Faces: Hypothetical Example 1. Yet, the fusion splicer 122 also notifies the technician when end-face fusion of the two optic fibers has “failed.” Let us assume, therefore, that end-face fusion of the two optic fibers 104 and 202 has failed, and that corrective action is now required.
Step 9, Part 1: Open Splicer; Remove Optic Fibers; Cut; Re-Fuse End Faces. Because the fusion splicer 122 indicated a “failure” at the end-face plane 138, (within the now-joined end-face region 140), it became necessary to open the fusion splicer 122. This is done by removing cover 128 from operational portion 126. The technician next removed now-joined first and second optic fibers 104 and 202 from their respective first and second fiber holders 112 and 206. (Please refer to
Failure to Successfully Fuse Optic Fiber End Faces: Hypothetical Example 2. Let us assume that the fusion splicer 122 has notified the technician that end-face fusion of the optic fibers has again “failed,” and that corrective action is required.
Step 9, Part 2: Open Splicer; Remove Optic Fibers; Cut; Re-Fuse End Faces. Because the fusion splicer 122 indicated a “failure” at the end-face plane 138, (within the now-joined end-face region 140), it shall again be necessary to open the fusion splicer 122. (Please refer to Step 9-1 and
Step 10: End-Face Fusion of Optic Fibers Successful; Open Fusion Splicer. The end-face fusion of freshly-cleaved end portions of the optic fibers 104, 202 was again completed, which fusion splicer 122 indicated (
Step 11: Move Sleeve Over End-Spliced Area; Transfer Sleeved Area to Oven. After removing the spliced-together optic fibers 104, 202 (
Step 12: Melt-Protection Completed; Remove Optic Fiber; Bring Up Boot. After the procedure to protect optic fibers 104, 202 by melting protective plastic sleeve 110 over their fused end-faces is completed (
Prior Art Rubber Boot vis-à-vis Example of Boot of Present Subject Matter.
Prior Art Fiber Stub Length vis-à-vis Stub Length of Present Subject Matter.
What has been illustrated and described in this application is an elongated optic fiber stub portion and an associated method. While the present subject matter has been described with reference to exemplary embodiments, the present subject matter is not limited to these examples. On the contrary, many alternatives, changes, and/or modifications will become apparent to those of ordinary skill in the field of the present subject matter after this application is read. Thus, all such alternatives, changes, and/or modifications are to be treated as part of the present subject matter insofar as they fall within the spirit and scope of claims that follow.
