1. Field of the Disclosure
The technology of the disclosure relates generally to fiber optic cassettes, and particularly to a fiber optic cassettes which may be used as a feeder module or a distribution module in fiber optic equipment.
2. Technical Background
Benefits of optical fiber use include extremely wide bandwidth and low noise operation. Because of these advantages, optical fiber is increasingly being used for a variety of applications, including but not limited to broadband voice, video, and data transmissions. Fiber optic networks employing optical fibers are being developed and used to deliver voice, video, and data transmissions to subscribers over both private and public networks. These fiber optic networks often include separated connection points at which it is necessary to link optical fibers in order to provide “live fiber” from one connection point to another connection point. In this regard, fiber optic equipment is located in data distribution centers or central offices to support interconnections.
The fiber optic equipment is customized based on application need. The fiber optic equipment is typically included in housings. The housing may be individually located cabinets or may be shelves or chassis in equipment racks for organizational purposes and to optimize use of space. One example of such fiber optic equipment is a fiber optic cassette or module. A fiber optic cassette is designed to provide cable-to-cable fiber optic connections and manage the polarity of fiber optic cable connections. A fiber optic cassette may be mounted in an enclosure or cabinet, or to a chassis or housing which is then mounted inside an equipment rack.
Embodiments disclosed in the detailed description include a fiber optic cassette. The fiber optic cassette has a housing having an interior, a component section and a front section. The component section is positioned in the interior. A plurality of fiber optic adapters having an internal end and an external end are positioned through a panel face that separates the front section and the component section. A single splice holder is positioned in the fiber optic component section, wherein the single splice holder is adapted to hold a single fiber splice. A mass splice holder is positioned in the fiber optic component section, wherein the mass splice holder is adapted to hold a mass splice. A pigtail cable assembly is positioned in the fiber optic component section. The pigtail cable assembly comprises a plurality of optical fibers, and is adapted to provide for at least one of the plurality of optical fibers to connect to one of the fiber optic adapters at a one end of the optical fibers. The pigtail cable assembly is modifiable to provide for the plurality of optical fibers to connect to one of a mass splice held by the mass splice holder and single fiber splices held by the single fiber splice holder at another end.
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 in the detailed description include a fiber optic cassette. The fiber optic cassette has a housing having an interior, a component section and a front section. The component section is positioned in the interior. A plurality of fiber optic adapters having an internal end and an external end are positioned through a panel face that separates the front section and the component section. A single splice holder is positioned in the fiber optic component section, wherein the single splice holder is adapted to hold a single fiber splice. A mass splice holder is positioned in the fiber optic component section, wherein the mass splice holder is adapted to hold a mass splice. A pigtail cable assembly is positioned in the fiber optic component section. The pigtail cable assembly comprises a plurality of optical fibers, and is adapted to provide for at least one of the plurality of optical fibers to connect to one of the fiber optic adapters at a one end of the optical fibers. The pigtail cable assembly is modifiable to provide for the plurality of optical fibers to connect to one of a mass splice held by the mass splice holder and single fiber splices held by the single fiber splice holder at another end.
In this regard, a pigtail cable assembly 10 according to an exemplary embodiment is illustrated in
A first end 24 of the optical fibers 20 at the first end section 14 is connectorized with fiber optic connectors 26, and therefore, adapted to be connected to a fiber optic adapted. One or more of the first ends 24 may be received in one end of a fiber optic adapter (not shown in
In
Alternatively or additionally, the second end section 16 may be severed from the mid-section 12 at a sever site 34. The sever site 34 may be at any position along the length of the fiber optic cable 18 in the mid-section 12. In the case of the fiber optic cable 18 being a ribbon cable, the sever site may be in the mid-section 12 where the matrix 22 remains on the ribbon cable, i.e. has not been removed. Severing the second end section 16 from the mid-section 12 may be accomplished by any suitable means for severing the fiber optic cable 18, for example by cutting. After the second end section 16 is severed from the mid-section 12, the mid-section 12 may be terminated at a mass splice 38 as shown in
Referring now to
The pigtail cable assembly 10, 10′ may be installed in fiber optic equipment, including, an enclosure, cassette, module, shelf, or the like. For purposes of facilitating discussion of the embodiments, the term “cassette” will be used, but it should be understood that any type of fiber optic equipment is contemplated by the embodiments. The cassette 50 may mount or position in other fiber optic equipment, including, but not limited to, a cabinet, enclosure, local connection point, fiber distribution hub, or the like.
In this regard,
Referring now to
The fiber optic cable 18, routes in the interior 56 in a manner to provide slack and other management of the fiber optic cable 18 and to facilitate the positioning of the optical fibers 20 of the second end section 16 for connection and/or termination at the one end of the single fiber splices 30 positioned in the single fiber splice holder 62. The optical fiber 20 may then be spliced to optical fiber 32 connected to the other end of the single fiber splice 30. Although not shown in
Referring now to
Any number of fiber optic cables 18 and optical fibers 20, 44 may be positioned in the cassette 50. Additionally, any number of single fiber splice holders 62 holding any number of single fiber splices 30 may be positioned in the component section 56 of the cassette 50. Similarly, any number of mass splice holders 64 holding any number of mass splices 38 may be positioned in the component section 56 of the cassette 50. Further, the cassette 50 may have one design and be used as a feeder cassette or a distribution cassette depending on whether the pigtail cable assembly 10 provides for mass splicing of the fiber optic cable 18, for example a ribbon cable, or individual splicing of the optical fibers. In other words, only one pigtail cable assembly 10 has to be provided and, whether a feeder cassette or a distribution cassette is needed, the second end section 16 may be severed or not severed at the sever point 36. Severing the second end section 16 can be performed at the factory or in the field.
The cassette 50(1) may be used as a feeder cassette receiving a feeder cable shown as the fiber optic cable 42(1). The fiber optic cable 42(1) may be a twelve fiber ribbon cable which is spliced to the fiber optic cable 18(1), which may also be a twelve (12) fiber ribbon cable. The fiber optic cable 42(1) is spliced to the fiber optic cable 18(1) by mass splice 38(1). The individual optical fibers 20(1) separate and connect to the internal ends of respective fiber optic adapters 58(1) in the cassette 50(1). Optical fibers 74(2) and 74(3), which may be in the form of individual jumpers or jumpers in a fiber optic cable, connect at one end to the external ends of the fiber optic adapters 58(1) to establish an optical connection between the optical fibers 20(1) and the optical fibers 74(2) and 74(3). Six optical fibers 20(1) optically connect to six optical fibers 74(2), and five optical fibers 20(1) optically connect to five optical fibers 74(3). In
The six optical fibers 74(2) route to cassette 50(2) and connect to the external ends of fiber optic adapters 58(2) in cassette 50(2). In
The five optical fibers 74(3) route to cassette 50(3) and connect to the external ends of fiber optic adapters 58(3) in cassette 50(3). In
The single optical fiber 76 routes to the optical splitter 72, which in
The enclosure 70 may include other fiber optic components for example, without limitation, additional splitters, CWDM, WDM, feeder terminal blocks, distribution terminal blocks, fiber and cable routing guides, and strain relief devices, to name just a few.
Further, 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 bare optical fibers, loose-tube optical fibers, tight-buffered optical fibers, ribbonized optical fibers, bend-insensitive optical fibers, or any other expedient of a medium for transmitting light signals. An example of a bend-insensitive, or bend resistant, optical fiber is ClearCurve® optical fiber, manufactured by Corning Incorporated. Suitable fibers of this type are disclosed, for example, in U.S. Patent Application Publication Nos. 2008/0166094 and 2009/0169163.
Bend resistant multimode optical fibers may comprise a graded-index core region and a cladding region surrounding and directly adjacent to the core region, the cladding region comprising a depressed-index annular portion comprising a depressed relative refractive index relative to another portion of the cladding. The depressed-index annular portion of the cladding is preferably spaced apart from the core. Preferably, the refractive index profile of the core has a parabolic or substantially curved shape. The depressed-index annular portion may, for example, comprise a) glass comprising a plurality of voids, or b) glass doped with one or more downdopants such as fluorine, boron, individually or mixtures thereof. The depressed-index annular portion may have a refractive index delta less than about −0.2% and a width of at least about 1 micron, said depressed-index annular portion being spaced from said core by at least about 0.5 microns.
In some embodiments that comprise a cladding with voids, the voids in some preferred embodiments are non-periodically located within the depressed-index annular portion. By “non-periodically located” we mean that when one takes a cross section (such as a cross section perpendicular to the longitudinal axis) of the optical fiber, the non-periodically disposed voids are randomly or non-periodically distributed across a portion of the fiber (e.g. within the depressed-index annular region). Similar cross sections taken at different points along the length of the fiber will reveal different randomly distributed cross-sectional hole patterns, i.e., various cross sections will have different hole patterns, wherein the distributions of voids and sizes of voids do not exactly match for each such cross section. That is, the voids are non-periodic, i.e., they are not periodically disposed within the fiber structure. These voids are stretched (elongated) along the length (i.e. generally parallel to the longitudinal axis) of the optical fiber, but do not extend the entire length of the entire fiber for typical lengths of transmission fiber. It is believed that the voids extend along the length of the fiber a distance less than about 20 meters, more preferably less than about 10 meters, even more preferably less than about 5 meters, and in some embodiments less than 1 meter.
The multimode optical fiber disclosed herein exhibits very low bend induced attenuation, in particular very low macrobending induced attenuation. In some embodiments, high bandwidth is provided by low maximum relative refractive index in the core, and low bend losses are also provided. Consequently, the multimode optical fiber may comprise a graded index glass core; and an inner cladding surrounding and in contact with the core, and a second cladding comprising a depressed-index annular portion surrounding the inner cladding, said depressed-index annular portion having a refractive index delta less than about −0.2% and a width of at least 1 micron, wherein the width of said inner cladding is at least about 0.5 microns and the fiber further exhibits a 1 turn, 10 mm diameter mandrel wrap attenuation increase of less than or equal to about 0.4 dB/turn at 850 nm, a numerical aperture of greater than 0.14, more preferably greater than 0.17, even more preferably greater than 0.18, and most preferably greater than 0.185, and an overfilled bandwidth greater than 1.5 GHz-km at 850 nm.
50 micron diameter core multimode fibers can be made which provide (a) an overfilled (OFL) bandwidth of greater than 1.5 GHz-km, more preferably greater than 2.0 GHz-km, even more preferably greater than 3.0 GHz-km, and most preferably greater than 4.0 GHz-km at an 850 nm wavelength. These high bandwidths can be achieved while still maintaining a 1 turn, 10 mm diameter mandrel wrap attenuation increase at an 850 nm wavelength of less than 0.5 dB, more preferably less than 0.3 dB, even more preferably less than 0.2 dB, and most preferably less than 0.15 dB. These high bandwidths can also be achieved while also maintaining a 1 turn, 20 mm diameter mandrel wrap attenuation increase at an 850 nm wavelength of less than 0.2 dB, more preferably less than 0.1 dB, and most preferably less than 0.05 dB, and a 1 turn, 15 mm diameter mandrel wrap attenuation increase at an 850 nm wavelength, of less than 0.2 dB, preferably less than 0.1 dB, and more preferably less than 0.05 dB. Such fibers are further capable of providing a numerical aperture (NA) greater than 0.17, more preferably greater than 0.18, and most preferably greater than 0.185. Such fibers are further simultaneously capable of exhibiting an OFL bandwidth at 1300 nm which is greater than about 500 MHz-km, more preferably greater than about 600 MHz-km, even more preferably greater than about 700 MHz-km. Such fibers are further simultaneously capable of exhibiting minimum calculated effective modal bandwidth (Min EMBc) bandwidth of greater than about 1.5 MHz-km, more preferably greater than about 1.8 MHz-km and most preferably greater than about 2.0 MHz-km at 850 nm.
Preferably, the multimode optical fiber disclosed herein exhibits a spectral attenuation of less than 3 dB/km at 850 nm, preferably less than 2.5 dB/km at 850 nm, even more preferably less than 2.4 dB/km at 850 nm and still more preferably less than 2.3 dB/km at 850 nm. Preferably, the multimode optical fiber disclosed herein exhibits a spectral attenuation of less than 1.0 dB/km at 1300 nm, preferably less than 0.8 dB/km at 1300 nm, even more preferably less than 0.6 dB/km at 1300 nm.
In some embodiments, the numerical aperture (“NA”) of the optical fiber is preferably less than 0.23 and greater than 0.17, more preferably greater than 0.18, and most preferably less than 0.215 and greater than 0.185.
In some embodiments, the core extends radially outwardly from the centerline to a radius R1, wherein 10<R1<40 microns, more preferably 20<R1<40 microns. In some embodiments, 22<R1<34 microns. In some preferred embodiments, the outer radius of the core is between about 22 to 28 microns. In some other preferred embodiments, the outer radius of the core is between about 28 to 34 microns.
In some embodiments, the core has a maximum relative refractive index, less than or equal to 1.2% and greater than 0.5%, more preferably greater than 0.8%. In other embodiments, the core has a maximum relative refractive index, less than or equal to 1.1% and greater than 0.9%.
In some embodiments, the optical fiber exhibits a 1 turn, 10 mm diameter mandrel attenuation increase of no more than 1.0 dB, preferably no more than 0.6 dB, more preferably no more than 0.4 dB, even more preferably no more than 0.2 dB, and still more preferably no more than 0.1 dB, at all wavelengths between 800 and 1400 nm.
The inner annular portion 230 has a refractive index profile Δ2(r) with a maximum relative refractive index Δ2MAX, and a minimum relative refractive index Δ2MIN, where in some embodiments Δ2MAX=Δ2MIN. The depressed-index annular portion 250 has a refractive index profile Δ3(r) with a minimum relative refractive index Δ3MIN. The outer annular portion 260 has a refractive index profile Δ4(r) with a maximum relative refractive index Δ4MAX, and a minimum relative refractive index Δ4MIN, where in some embodiments Δ4MAX=Δ4MIN. Preferably, Δ1MAX>Δ2MAX>Δ3MIN. In some embodiments, the inner annular portion 230 has a substantially constant refractive index profile, as shown in
Many modifications and other 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. 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 is a continuation of International Application No. PCT/US11/27811 filed Mar. 10, 2011, which claims the benefit of priority to U.S. Application No. 61/312,524, filed Mar. 10, 2010, both applications being incorporated herein by reference.
Number | Date | Country | |
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61312524 | Mar 2010 | US |
Number | Date | Country | |
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Parent | PCT/US11/27811 | Mar 2011 | US |
Child | 13603894 | US |