1. Field of the Invention
The present invention relates to optical fiber connecting hardware. More particularly, the present invention relates to a ferrule and/or optical fiber optimized for epoxy usage when terminating an optical fiber within a ferrule.
2. Description of the Related Art
It is known in the background art, that a fiber optic cable may be cut and terminated at a connector, jumper or attenuator, or other such structure. A typical termination includes a ferrule having a central bore passing through a center thereof. A length of optical fiber is exposed at the end of the cut fiber optic cable. The optical fiber is passed through the central bore in the ferrule and cut flush with the end of the ferrule. An epoxy secures the optical fiber within the central bore, and the cut end of the optical fiber is polished, along with the end of the ferrule, to finish the termination.
U.S. Pat. No. 6,074,100, which is herein incorporated by reference, shows a ferrule and typical termination method using a ferrule.
In
In preparation for bonding, a bead or ring of bonding adhesive 240 is applied to the outer surface 238 of the aft body 226, corresponding to region A, and a layer of bonding adhesive 242, corresponding to region B, is applied to the optical fiber 212 and inner jacket 216. The bonding adhesives 240, 242 in regions A and B are the same and, furthermore, are selected such that the Glass Transition Temperature (TG) is greater than the maximum temperature anticipated in the operating environment of the terminus. Prior to bonding, the strengthening members 218 are folded rearwardly over the outer jacket 220. A shrink tubing 244, which will subsequently overlay the strengthening member 218, is used to temporarily preposition the strengthening member 218 over the outer jacket 220.
In
Then, various sanding or polishing operations are preformed in order to recess the cut end of the optical fiber 212 below the external face surface 228 of the rigid ferrule 224, as illustrated in
The present invention includes an improved system for dealing with the epoxy 242 in section B of
The Applicants have appreciated drawbacks in the connector designs in the prior art due to the dimensional relationship between the ID of the rigid ferrule 224 and the OD of the optical fiber 212. For example, play exists between the ID of the rigid ferrule 224 and the OD of the optical fiber 212. The play is provided to accommodate the existence of the epoxy 242 between the ID of the channel 230 and the OD of the optical fiber 212. However, the play can sometimes allow the optical fiber 212 to abut against one side of the ID of the channel 230 and create a maximum gap between the ID of the channel 230 and the OD of the optical fiber 212 on the opposite side of the optical fiber 212. Hence, the center axis of the optical fiber 212 is not concentric with the center axis of the channel 230, and/or is not controlled to remain concentric along the length of the fiber optic cable 208.
When the center axis of the optical fiber 212 is not concentric with the center axis of the channel 230, there can be signal loss, e.g., attenuation, at the connector's interface, e.g., polished end profile 250, as it communicates the optical fiber's signal to another optical fiber end profile 250 or to a device. In other words, the two abutting fiber end profiles 250 at a connection will not be properly aligned and light will not completely pass between the two misaligned fiber end profiles 250.
It is an objective of the present invention to address the above described drawbacks and other perceived drawbacks in the optical fiber terminations of the background art.
These and other objectives are accomplished by a device comprising a ferrule having a first end and a second end; a substantially circular channel extending from said first end of said ferrule to said second end of said ferrule, said channel having an inner diameter; and at least one groove formed into said inner diameter of said channel and extending from said first end of said ferrule to said second end of said ferrule.
These and other objectives are further accomplished by a device comprising a substantially circular optical fiber, said optical fiber having an outer diameter; and at least one notch formed into said outer diameter of said optical fiber, wherein said notch extends in a longitudinal direction of said optical fiber.
These and other objectives are yet further accomplished by a device comprising a ferrule having a first end and a second end; a substantially circular channel extending from said first end of said ferrule to said second end of said ferrule, said channel having an inner diameter; a substantially circular optical fiber, said optical fiber having an outer diameter and residing within said channel; at least one groove or notch formed into said inner diameter of said channel or said outer diameter of said optical fiber; and epoxy within said at least one groove or notch attaching said optical fiber within said channel.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limits of the present invention, and wherein:
The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”
It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.
Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.
At least one groove 109 is formed into the inner diameter of the channel 107 and extends from the first end 103 of the ferrule 101 to the second end 105 of the ferrule 101. In a preferred embodiment, the at least one groove 109 includes a plurality of grooves, such as four grooves 109A, 109B, 109C and 109D, which are approximately equally spaced from each other around the inner circumference of the channel 107 and extending into a material forming the ferrule 101, e.g., a ceramic material. In
In use, a substantially circular optical fiber is inserted into the central channel 107 of the ferrule 101, such as the optical fiber 212 of the fiber optic cable 208, as shown in
The fluted ferrule structures illustrated in
As shown in
Some ferrules are designed to hold more than one optical fiber in an ordered array. Ferrules having multiple channels could also benefit by having the optical fibers held within the ferrule in such a way that the center axis of each optical fiber is located more precisely along the center axis of its respective channel.
For example,
Each channel 107-X of the MT type ferrule 119 can be sized to closely match the outer diameter OD of the optical fiber 212-X (e.g., exceeding the outer diameter OD of the optical fiber 212 by less than 4%, more preferably by less than 2%, and most preferably by less than 1%). Each channel 107-X of the MT type ferrule 119 may incorporate grooves 109 to hold epoxy, such that the optical fiber 212-X for that channel 107-X can be secured therein, even while the inner diameter of the channel 107-X is approximately equal to the outer diameter of the optical fiber 212-X.
To sum up the first embodiment, many optical fibers are connected using mechanical physical contact connectors. The fiber is typically bonded into a ceramic ferrule, cleaved and polished. The ferrule assembly is mated to a second ferrule assembly using a solid or split sleeve. The ferrule assemblies and sleeve are commonly surrounded by connector and adapter housings. A gap exists between the outer diameter of the fiber and the inner diameter of the channel within the ferrule. Epoxy is commonly located in the fiber-to-ferrule gap. The gap allows the fiber to move off center in the channel of the ferrule. Off center fibers align poorly, creating signal loss. The proposed fluted ferrule has longitudinal grooves along the ferrule's inner circumference to hold epoxy and form the fiber-to-ferrule bond. The ferrule channel's inner diameter ID can be reduced to provide better fiber alignment to the center of the channel, and lower signal loss across mated/facing fiber ends. Also, epoxy can be added after the fiber is inserted into the channel, hence reducing fiber breaks and scrap. One or more flutes (grooves) can be added to each ferrule, and the concept can be extended to multi-fiber ferrules and expanded beam terminations.
A second embodiment of the present invention is illustrated in
In a preferred embodiment, the at least one notch 153 includes a plurality of notches, such as four notches 153A, 153B, 153C and 153D, approximately equally spaced from each other around the cylindrical outer surface 155 of the optical fiber 151 and extending into a material forming the cladding layer 157 of the optical fiber 151. In
Each notch 153 may extend into the cladding layer 157 of the optical fiber 151 to a depth of at least one percent of a total diameter of the optical fiber 151. The notches 153 do not extend into the central, optical signal carrying medium 159, e.g., glass or optical plastic. For example, the notches 153 might extend into the cladding layer 157 of the optical fiber 151 by at least 2%, or more preferably by at least 4%, of the overall diameter OD of the optical fiber 151.
In use, the optical fiber 151 having the notches 153 in its cylindrical outer surface 155 is inserted into the central bore 230 of a rigid ferrule 224, such as the rigid ferrule 224 depicted in
The first and second embodiments of the invention may be combined whereby both the inner diameter ID of the channel 107 includes grooves 109 and the cylindrical outer surface 155 of the optical fiber 151 includes notches 153.
In the background art, optical fibers are commonly terminated with a single fiber, physical contact connector. The fiber is bonded into a cylindrical ferrule, cleaved and polished to form a first ferrule assembly. The first ferrule assembly is mated to a second ferrule assembly using a circular solid or split sleeve that surrounds the outside surfaces of the cylindrical ferrules and brings the ferrule ends into proper end-to-end alignment. The ferrule assemblies are commonly surrounded by connector housings. The split or solid sleeve is commonly surrounded by an adapter housing.
The quality of the connection depends largely on how accurately the first fiber end is aligned to the second fiber end within the connector. In the prior art, a gap exists between the outside surface of the fiber and the inside surface of the ferrule through hole. The gap exists to provide space for epoxy that bonds the fiber into the ferrule through hole. The gap allows the center axis of the fiber to move away from the center axis of the ferrule in random directions. It is likely that fibers in two mated connectors (whether mated single channel connectors or mated multichannel connectors) are not perfectly aligned resulting in increased connection loss, e.g., signal attenuation across the connector.
In accordance with the first embodiment of the present invention, longitudinal grooves are added to the inside of the ferrule through hole or channel, and the diameter of the through channel (as measured between sections of the through channel not possessing the longitudinal grooves) is reduced, so that the diameter of the ferrule through channel within the ferrule more closely matches the outer diameter of the optical fiber to be held within the fiber through channel. The longitudinal grooves provide space for accommodating epoxy to bond the fiber to the ferrule. The smaller through hole diameter improves the fiber-to-channel concentricity, connector performance and reduces scrap, e.g., discarded or recycled connectors due to off-center optical fibers causing attenuation levels exceeding an acceptable threshold.
The longitudinal groove or grooves also allow epoxy to be applied after the fiber is inserted, e.g., by a syringe. Inserting the epoxy after the optical fiber is inserted into the ferrule through channel reduces the initial force needed to insert the optical fiber into the ferrule through channel, hence reducing fiber breaks and reducing scrap, e.g., discarded or recycled connectors due to defective connector performance resulting from fiber breakage within the connector.
In accordance with the second embodiment of the present invention, longitudinal notches are provided in the outer cylindrical surface of the optical fiber. The notches received the epoxy and allow the tolerance between the ferrule channel and the optical fiber to be much more closely matched. Hence, the same advantages, as outlined in connection with the grooves may be equally accomplished. It is also possible to include one or more grooves in the ferrule channel in combination with one or more notches in the outer cylindrical surface of the optical fiber. Again, the same advantages, as outlined in connection with the grooves may be equally accomplished.
Although the drawings have illustrated a single core optical fiber, the optical fiber may include multiple cores. Multi-core optical fiber also needs to be precisely concentrically located within its ferrule channel. With the smaller sizes of the satellite cores associated with multi-core optical fibers, the centering within the ferrule channel becomes even more important. Also, the ability to load a multi-core optical fiber into an empty channel, and then rotate the multi-core fiber to clock the satellite cores to a proper position prior to inserting epoxy into the grooves or notches, e.g., by a syringe, is particularly advantageous.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
Number | Date | Country | |
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61745829 | Dec 2012 | US |