U.S. patent application number 12/367844 was filed with the patent office on 2009-06-11 for fiber optic drop terminals for multiple dwelling units.
Invention is credited to Guy Castonguay, Donnie Ray Clapp, JR., Terry Dean Cox, Thomas Shaw Liggett, Karyne Poissant Prevratil, Diana Rodriguez.
Application Number | 20090148119 12/367844 |
Document ID | / |
Family ID | 39432867 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090148119 |
Kind Code |
A1 |
Castonguay; Guy ; et
al. |
June 11, 2009 |
Fiber Optic Drop Terminals for Multiple Dwelling Units
Abstract
There is provided fiber drop terminals ("FDTs") and related
equipment for providing selective connections between optical
fibers of distribution cables and optical fibers of drop cables,
such as in multiple dwelling units. The FDTs require relatively
little area and/or volume while providing convenient connectivity
for a relatively large number of optical connections. The FDTs
include adapters for optically connecting the connectors, and the
adapters of some FDTs are adapted to rotate, move, or otherwise be
removed to provide convenient access for technicians. Some FDTs and
the related equipment are adapted for use with microstructured
optical fiber having preferred bend characteristics.
Inventors: |
Castonguay; Guy; (Fort
Worth, TX) ; Clapp, JR.; Donnie Ray; (Fort Worth,
TX) ; Cox; Terry Dean; (Keller, TX) ; Liggett;
Thomas Shaw; (Keller, TX) ; Prevratil; Karyne
Poissant; (Watauga, TX) ; Rodriguez; Diana;
(Alvarado, TX) |
Correspondence
Address: |
CORNING INCORPORATED
INTELLECTUAL PROPERTY DEPARTMENT, SP-TI-3-1
CORNING
NY
14831
US
|
Family ID: |
39432867 |
Appl. No.: |
12/367844 |
Filed: |
February 9, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11712035 |
Feb 28, 2007 |
7499622 |
|
|
12367844 |
|
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|
Current U.S.
Class: |
385/135 ;
385/137 |
Current CPC
Class: |
H04Q 1/023 20130101;
H04Q 1/028 20130101; H04Q 1/021 20130101; G02B 6/3897 20130101;
G02B 6/4452 20130101; G02B 6/4442 20130101 |
Class at
Publication: |
385/135 ;
385/137 |
International
Class: |
G02B 6/38 20060101
G02B006/38; G02B 6/00 20060101 G02B006/00 |
Claims
1-16. (canceled)
17. A strain relief device adapted for use with microstructured
optical fiber, the strain relief device comprising: a body defining
an axis generally aligned with the axis of the microstructured
optical fibers to be strain relieved; a plurality of slots adapted
to receive the microstructured optical fibers; and a compression
device adapted for positioning around the body and the
microstructured optical fibers received within the plurality of
slots to apply a force upon the microstructured optical fibers to
strain relieve the optical fibers.
18. A strain relief device according to claim 17, wherein the body
defines a generally cylindrical shape.
19. A strain relief device according to claim 17, wherein the
plurality of slots is defined along the perimeter of the body such
that a portion of the microstructured optical fibers is positioned
radially outward of the perimeter of the body.
20. A strain relief device according to claim 17, wherein the body
defines a circumferential slot adapted to receive the compression
device, wherein the slot defines at least one shoulder to prevent
axial movement of the compression device.
21. A strain relief device according to claim 17, wherein the
compression device comprises a wire tie device.
22. A strain relief device according to claim 17 further comprising
a spring clip to selectively mount the strain relief device within
a fiber optic enclosure.
23. A strain relief device according to claim 17, wherein the FDT
is adapted to receive at least one optical fiber comprising a
microstructured optical fiber comprising a core region and a
cladding region surrounding the core region, the cladding region
comprising an annular hole-containing region comprised of
non-periodically disposed holes.
24. A strain relief device according to claim 23, wherein the
microstructured fiber has an 8 mm macrobend induced loss at 1550 nm
of less than 0.2 dB/turn.
25. A fiber drop terminal ("FDT") adapted for use in a fiber-optic
network of a multiple dwelling unit to selectively optically
connect at least one connectorized optical fiber of a distribution
cable to a connectorized optical fiber of at least one drop cable,
the FDT comprising: a base defining a back wall and at least one
sidewall extending outwardly from the back wall, wherein the base
defines at least one opening for passage of the distribution cable
and the drop cable through at least one of the back wall and
sidewall; a cover adapted to selectively connect to the sidewall
generally opposite the back wall; at least one plurality of
adapters joined to at least one of the back wall and the sidewall
of the base, wherein the adapters are adapted to receive a
connector of the distribution cable and a connector of the drop
cable to optically connect the connectorized optical fiber of the
distribution cable to the connectorized optical fiber of the drop
cable; and a distribution cover provided between the back wall and
the cover, wherein the distribution cover is adapted to provide
limited access to the portion of the adapters that are adapted to
receive a connector of the distribution cable.
26. An FDT according to claim 25, wherein the cover is rotatably
attached to the base and the distribution cover is rotatably
attached to the base.
27. An FDT according to claim 25 further comprising a fanout
positioned between the distribution cover and the base and
optically connecting the optical fiber of the distribution cable
with the portion of the adapters that are adapted to receive a
connector of the distribution cable.
28. An FDT according to claim 25, wherein the at least one opening
of the base comprises an opening adapted to receive a multi-fiber
adapter.
29. An FDT according to claim 25, wherein the at least one opening
of the base comprises an opening adapted to strain relieve and seal
the drop cables passing therethrough.
30. An FDT according to claim 25, wherein the FDT is adapted to
receive at least one optical fiber comprising a microstructured
optical fiber comprising a core region and a cladding region
surrounding the core region, the cladding region comprising an
annular hole-containing region comprised of non-periodically
disposed holes.
31. An FDT according to claim 30, wherein the microstructured fiber
has an 8 mm macrobend induced loss at 1550 nm of less than 0.2
dB/turn.
32-43. (canceled)
Description
RELATED APPLICATIONS
[0001] The present application is a Divisional application of U.S.
Ser. No. 11/712,035 filed on Feb. 28, 2007, the disclosure of which
is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention is related to fiber drop terminals,
and more particularly, to fiber drop terminals defining novel
sizes, shapes, and/or functionality.
[0004] 2. Description of Related Art
[0005] To provide improved performance to subscribers, fiber optic
networks are increasingly providing optical fiber connectivity
directly to the subscribers. As part of various
fiber-to-the-premises (FTTP), fiber-to-the-home (FTTH), and other
initiatives (generally described as FTTx), such fiber optic
networks are providing the optical signals from distribution cables
through local convergence points ("LCPs") to fiber optic cables,
such as drop cables, that are run directly or indirectly to the
subscribers' premises. Such optical connectivity is increasingly
being provided to multiple dwelling units ("MDUs") in part because
of the relatively large density of subscribers located in an
MDU.
[0006] MDUs include apartments, condominiums, townhouses,
dormitories, hotels/motels, office buildings, factories, and any
other collection of subscriber locations that are in relatively
close proximity to one another. MDUs typically are all provided in
a single indoor environment, such as an office or condominium;
however, MDUs may also include a plurality of individual
structures, such as apartment complexes. Typically, if an MDU
comprises multiple structures, the optical fibers extending between
the structures are adapted for outdoor environments, whereas the
optical fibers extending within the structures are adapted for
indoor environments. Most conventional MDUs include an LCP located
in a generally central and selectively accessible location, such as
the basement, utility closet, or the like, or the LCP may be
located outside the MDU on an exterior wall, in a pedestal, in a
handhole, or the like. The LCP includes at least one fiber optic
cable that optically connects to a distribution cable. The LCP also
includes a connection point where the subscriber cables routed
through the building are optically connected to the distribution
cable.
[0007] In some situations the subscriber drop cables are not run
directly back to the LCP, but to a fiber drop terminal (also called
a fiber distribution terminal) ("FDT"). FDTs are commonly used in
MDUs to provide optical connectivity between riser cables
(generally oriented vertically in the MDU) and the plenum cables
(generally oriented horizontally in the MDU). However, such FDTs
are large and are generally not desirable for installation on each
floor or other section of an MDU based upon the size of their
footprint, visibility, and other considerations. Such large FDTs
are also relatively expensive to produce and are generally less
convenient to transport, install, and service.
[0008] Therefore, a need exists for FDTs that provide a require
relatively small area and/or volume and that provide convenient
access for technicians. In addition, a need exists for FDTs that
provide convenient and secure access to the optical connections
within the FDT.
BRIEF SUMMARY OF THE INVENTION
[0009] The various embodiments of the present invention address the
above needs and achieve other advantages by providing fiber drop
terminals ("FDTs") that are adapted for use with microstructured
optical fibers and/or other optical fibers that enable unique size,
shapes, features, and other parameters. The FDTs of the present
invention provide not only a small "footprint" (area/volume
required for placement of the FDT), but the FDTs also provide for
convenient and secure access to the optical connections within the
FDT. Still further advantages will be appreciated by those skilled
in the art.
[0010] One embodiment of the present invention comprises an FDT
adapted for use in a fiber optic network of a multiple dwelling
unit to selectively optically connect at least one connectorized
optical fiber of a distribution cable to a connectorized optical
fiber of at least one drop cable. The FDT comprises a base with a
back wall and a sidewall extending outwardly from the back wall,
and the base defines at least one opening for passage of the
distribution cable and the drop cable. The FDT also includes a
cover that selectively connects to the sidewall. The base of the
FDT includes pluralities of adapters that receive a connector of
the distribution cable and a connector of the drop cable to
optically connect the connectorized optical fiber of the
distribution cable to the connectorized optical fiber of the drop
cable. The pluralities of adapters are pivotably joined to the base
to enable a technician to move the adapters relative to the base to
allow the base to define a smaller area while still providing
convenient access to the adapters, connectors, or other
hardware.
[0011] Further embodiments of the present invention include FDTs
with a distribution cover provided between the base and the cover.
The distribution cover is adapted to provide limited access to the
portion of the adapters that receive a connector of the
distribution cable. Therefore, the service provider may prevent
unauthorized access to the service provider side of the FDT. In
addition, further embodiments comprise a removable and/or rotatable
bracket for mounting the pluralities of adapters to thereby allow
convenient handling of the pluralities of adapters within the
FDT.
[0012] Still further embodiments of the present invention provide
fiber optic hardware associated with FDTs and other fiber optic
closures. Therefore, the FDTs and associated hardware of various
embodiments of the present invention provide for convenient and
secure optical connectivity while requiring relative smaller areas
and volumes when compared to prior art closures.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0013] Having thus described the invention in general terms,
reference will now be made to the accompanying drawings, which are
not necessarily drawn to scale and are meant to be illustrative and
not limiting, and wherein:
[0014] FIG. 1 is a perspective view of a fiber drop terminal
("FDT") in accordance with a first embodiment of the present
invention, illustrating the cover selectively removed from the
base;
[0015] FIG. 2 is a perspective view of the FDT of FIG. 1,
illustrating four pluralities of adapters joined to the back wall
of the base and a plurality of openings in the sidewall of the base
for passage of four distribution cables and 48 drop cables;
[0016] FIG. 3 is a perspective view of the four pluralities of
adapters of the FDT of FIG. 1, illustrating horizontal hinge at the
lower end of vertical bars to which the pluralities of adapters are
connected and illustrating the latch at the upper end of the
vertical bars;
[0017] FIG. 4 is a perspective view of the four pluralities of
adapters of the FDT of FIG. 1, illustrating a first plurality of
adapters rotated downward generally about a horizontal axis;
[0018] FIG. 5 is a perspective view of the four pluralities of
adapters of the FDT of FIG. 1, illustrating the second plurality of
adapters rotated downward generally about a horizontal axis;
[0019] FIG. 6 is a perspective view of the four pluralities of
adapters of the FDT of FIG. 1, illustrating the third plurality of
adapters rotated downward generally about a horizontal axis;
[0020] FIG. 7 is an enlarged perspective view of the fourth
plurality of adapters of the FDT of FIG. 1, illustrating a bracket
at the upper end of the vertical bar, wherein the bracket defines a
slot adapted to enable selective rotation of the plurality of
adapters about a generally vertical axis;
[0021] FIG. 8 is an enlarged perspective view of the fourth
plurality of adapters of the FDT of FIG. 1, illustrating the
vertical bar repositioned relative to the bracket as compared to
the view of FIG. 7;
[0022] FIG. 9 is an enlarged perspective view of the fourth
plurality of adapters of the FDT of FIG. 1, illustrating the
vertical bar rotated about a generally vertical axis relative to
the view of FIG. 8;
[0023] FIG. 10 is schematic view of the bottom of the four
pluralities of adapters of the FDT of FIG. 1, illustrating the
horizontal hinge of the three pluralities of adapters and the
bracket of the fourth plurality of adapters;
[0024] FIG. 11 is a perspective view of the FDT of FIG. 1,
illustrating the cover selectively attached to the base;
[0025] FIG. 12 is a perspective view of an FDT in accordance with a
second embodiment of the present invention, illustrating two
pluralities of adapters and two splice trays mounted to the base,
wherein the splice trays enable splicing of the drop cables to
connectorized pigtails;
[0026] FIG. 13 is a perspective view of the FDT of FIG. 12,
illustrating a first plurality of adapters rotated downward
generally about a horizontal axis, wherein the latch comprises a
fastener for positioning through an opening in the vertical bar of
the plurality of adapters;
[0027] FIG. 14 is a perspective view of the FDT of FIG. 12,
illustrating a second plurality of adapters rotated downward
generally about a horizontal axis;
[0028] FIG. 15 is a perspective view of the FDT of FIG. 12,
illustrating the selective removal of one splice tray from the base
of the FDT;
[0029] FIG. 16 is an enlarged perspective view of grommets used in
the FDTs of both of the embodiments of FIGS. 1 and 12, illustrating
a first grommet adapted to receive 12 drop cables and a second
grommet (on the right) adapted to receive 24 drop cables;
[0030] FIG. 17 is a perspective view of a strain relief device
adapted for use with microstructured optical fiber in accordance
with one embodiment of the present invention, illustrating the
strain relief device within the FDT of FIG. 1 proximate the grommet
of FIG. 16;
[0031] FIG. 18 is an enlarged perspective view of the strain relief
device of FIG. 17, illustrating the plurality of slots adapted to
receive the microstructured optical fibers;
[0032] FIG. 19 is an enlarged perspective view of the strain relief
device of FIG. 17, illustrating a circumferential slot with at
least one shoulder adapted to receive and prevent axial movement of
a compression device;
[0033] FIG. 20 is an enlarged perspective view of the strain relief
device of FIG. 17, illustrating the compression device, comprising
a wire tie device, provided within the circumferential slot to
provide strain relief to the microstructured optical fibers;
[0034] FIG. 21 is a front schematic view of an FDT in accordance
with a third embodiment of the present invention, illustrating the
cover;
[0035] FIG. 22 is a perspective view of the FDT of FIG. 21,
illustrating the plurality of adapters and the distribution cover
provided between the back wall and the cover to provide limited
access to the portion of the adapters that are adapted to receive a
connector of the distribution cable;
[0036] FIG. 23 is a perspective view of the FDT of FIG. 21,
illustrating the distribution cover in an opened position, thus
allowing access to the portion of the adapters that are adapted to
receive a connector of the distribution cable;
[0037] FIG. 24 is a bottom schematic view of the FDT of FIG. 21,
illustrating the opening in the base for passage of the
distribution cable (on the left) and the opening in the base for
passage of the drop cables (on the right);
[0038] FIG. 25 is a perspective view of an FDT in accordance with a
fourth embodiment of the present invention, illustrating two
pluralities of adapters joined to a bracket that is selectively
removable from the base;
[0039] FIG. 26 is a perspective view of the FDT of FIG. 25,
illustrating the removal of the bracket from the base of the
FDT;
[0040] FIG. 27 is a perspective view of the FDT of FIG. 25,
illustrating the selective rotation of the bracket relative to the
base of the FDT;
[0041] FIG. 28 is a perspective view of a cover adapted to be
selectively connected to the base of the FDT of FIG. 25,
illustrating the generally dome shape of the cover;
[0042] FIG. 29 is a front schematic view of the cover of FIG.
28;
[0043] FIG. 30 is a side schematic view of the cover of FIG.
28;
[0044] FIG. 31 is a side schematic view of an alternative cover
adapted to be selectively connected to the base of an FDT similar
to the embodiment of FIG. 25, illustrating a protruding tab adapted
to be received within a mating slot in the base of the FDT to
selectively retain the cover relative to the base;
[0045] FIG. 32 is a front schematic view of the cover of FIG.
31;
[0046] FIG. 33 is a top schematic view of the sidewall of the base
of an FDT similar to the embodiment of FIG. 25, illustrating one
opening for passage of the distribution cable and plurality of
openings for passage of the drop cables;
[0047] FIG. 34 is a top schematic view of the sidewall of the base
of an FDT similar to the embodiment of FIG. 25, illustrating one
opening for passage of the distribution cable and two slots adapted
to allow passage of two or more drop cables, wherein each slot
defines at least one opened portion sized to allow passage of a
connector of a drop cable and each slot further defines other
portions sized to allow passage of the drop cable alone;
[0048] FIG. 35 is a perspective view of a strain relief device
adapted for use with an opening in an FDT, such as the opening for
passage of the distribution cable in the FDT of FIG. 25,
illustrating the generally frustoconical shape and the three ribs
along the frustoconical surface to provide improved strain relief
for the distribution cable; and
[0049] FIG. 36 is a perspective view of the strain relief device of
FIG. 35, illustrating the strain relief device selectively received
within the opening of the FDT to seal and strain relieve the
distribution cable.
DETAILED DESCRIPTION OF THE INVENTION
[0050] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the invention are shown. Indeed,
the invention may 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
satisfy applicable legal requirements. Although apparatus and
methods for providing optical connectivity between optical fibers
of distribution cables and drop cables are described and shown in
the accompanying drawings with regard to specific types of fiber
drop terminals, also known as fiber distribution terminals,
(collectively, "FDTs"), it is envisioned that the functionality of
the various apparatus and methods may be applied to any now known
or hereafter devised enclosures and related fiber optic network
equipment in which it is desired to provide optical connections
between optical fibers of any cables within the fiber optic
network. Like numbers refer to like elements throughout.
[0051] With reference to FIGS. 1-36, various FDTs and associated
equipment in accordance with some embodiments of the present
invention are illustrated. As mentioned above, although these
embodiments are described herein as being used as a network access
point optical connection for distribution cable(s) and drop cables
for multiple dwelling units ("MDUs"), it should be appreciated that
the embodiments of the present invention may be used at alternative
positions within the fiber optic network to connect any optical
fibers within the network. Furthermore, although the illustrated
embodiments are adapted for use within an MDU and do not include
much of the standard features of outdoor hardware, further
embodiments of the present invention include additional features,
designs, components, and other functionalities adapted for use
outside an MDU. As described more fully below, the illustrated
embodiments of the present invention are described as using
microstructured optical fiber; however, further embodiments of the
present invention are adapted to include any alternative type of
optical fiber. In addition, FDTs of certain embodiments of the
present invention include many of the dimensional, functional,
design, and other features of the fiber distribution terminals
(also referred to as "FDTs" and which are generally synonymous with
fiber drop terminals) disclosed in U.S. patent application Ser. No.
11/653,137 filed on Jan. 12, 2007, which is assigned to the present
assignee and the disclosure of which is incorporated in its
entirety by reference herein.
[0052] Turning now to the embodiment of FIGS. 1-11, an FDT adapted
for use in a fiber optic network of an MDU is provided. The FDT 10
enables a technician to selectively optically connect at least one
connectorized optical fiber of a distribution cable (not shown) to
a connectorized optical fiber of at least one drop cable (not
shown). The FDT comprises a base 12 defining a back wall 14 and a
sidewall 16 extending outwardly from the back wall. The back wall
14 of the illustrated embodiment comprises a two-part back wall to
allow convenient removal of some of the hardware therein, whereas
further embodiments of the present invention may comprise any
number of back wall(s). The base 12 of FIGS. 1-11 defines four
openings 18 for passage of the distribution cables and two openings
20 for passage of the drop cables through the sidewall 16. The term
"passage" for purposes of this patent application shall include the
passing of continuous optical fibers of the respective cable and
shall also include the passage of optical signals communicated
through the optical fibers even though the actual fiber may be
terminated and joined to a second optical fiber, such as in a
connector-adapter interface, a connector-connector interface, or
any other use of optical waveguides. Therefore, "passage" of the
optical fiber or cable is not limited to situations where the
actual fiber or cable pass into or out of the base; the optical
signal need only pass into or out of the base for there to be
"passage." Referring to FIG. 2, the openings 18 for passage of the
distribution cables comprise a multi-fiber adapter 19a for
receiving a multi-fiber connector of the distribution cable (not
shown), whereas the openings 20 for passage of the drop cables
comprise grommets that allow the drop cables to pass directly
through. For the embodiment of FIG. 2, a fanout device 19b is
provided to divide the optical fibers of the multi-fiber adapter
19a into individual optical fibers routed to the connectors of the
distribution cables described below. Further embodiments of the
present invention also provide openings in the back wall to allow
passage of the distribution cable(s) and/or drop cables.
[0053] The FDT of FIGS. 1-11 also includes a cover 22 adapted to
selectively connect to the sidewall 16 generally opposite the back
wall 14; however, further embodiments of the present invention
provide the cover at any location relative to the back wall. The
FDT 10 of FIGS. 1-11 also comprises four pluralities of adapters 24
joined to the back wall 14, whereas further embodiments provide the
plurality of adapters at any location relative to the base and/or
cover. The adapters 24 are adapted to receive a connector 26 of the
distribution cable and a connector 28 of the drop cable to
optically connect the connectorized optical fiber of the
distribution cable to the connectorized optical fiber of the drop
cable. The pluralities of adapters 24 of FIGS. 1-11 are pivotably
joined to the base 12 to provide convenient access to each of the
adapters while also allowing a relatively large number of adapters
(compared to prior art FDTs) to be provided within the FDT.
[0054] Turning again to the cover 22 of FIG. 1, the cover defines a
perimeter that on the top, left, and right sides defines a
generally inwardly-facing groove that is adapted to receive a
generally outwardly-facing lip 30 of the base to thereby enable the
cover to slideably engage the sidewall 16 of the base 12. Further
embodiments of the present invention include alternative designs to
provide a cover that may be selectively connected to the base
and/or that is selectively rotatable relative to the base.
[0055] Referring now to the pluralities of adapters 24 of the FDT
of FIGS. 1-11, the adapters 24 are connected with a vertical bar 32
that comprises a horizontal hinge 34 at a bottom end of the
vertical bar and a latch 36 adapted to enable selective rotation of
the plurality of adapters about a generally horizontal axis. The
hinge 34 may permanently attach the adapters 24 to the base 12, or
the hinge 34 may allow selective removal of the adapters from the
base. The latch 36 of the illustrated embodiment comprises two
prongs that may be squeezed together to allow passage through a
narrow slot to disconnect the vertical bar, and the narrow slot may
taper inwards so that the vertical bar may be connected without
squeezing the prongs together. Still further embodiments of the
present invention comprise alternative devices for providing
selectively moveable pluralities of adapters.
[0056] The vertical bars 32 of FIG. 3 each connect to twelve SC
adapters 24, whereas further embodiments of the present invention
connect any number of fiber optic connectors and any style of
optical connectors, including but not limited to LC, FC, MTP, and
any other single or multiple fiber connectors for single-mode or
multi-mode fiber. The adapters 24 define axes that are generally
oriented along a plane that is generally parallel to the back wall
of the base to allow the FDT 10 to have a generally low profile.
Although the adapters 24 are illustrated as extending in a
generally horizontal direction, further embodiments of the present
invention provide the adapters in a generally vertical direction
(such that the "vertical" bar becomes "horizontal"). Still further
embodiments of the present invention include adapters with axes
that extend in a generally orthogonal direction relative to the
back wall of the base and/or in other orientations.
[0057] The FDT 10 includes four pluralities of adapters 24, with
the first three adapters (in order of their ability to be moved to
access the plurality of adapters behind) having hinges 34 and
latches 36 as described above. Each plurality of adapters 24 is
positioned a certain distance from the back wall 14 to allow each
of the pluralities of adapters to be selectively moved by a
technician. As shown in FIG. 7, the fourth plurality of adapters 24
includes a vertical bar 32 that is joined to the base 14 by a
bracket 38 at each end of the vertical bar. The bracket 38 defines
a slot 40 adapted to enable selective rotation of the plurality of
adapters about a vertical axis. The slot 40 receives a standoff
device 42, such as a pin, and allows the pin to be moved within the
slot a certain distance and/or direction to enable the adapters 24
(and any connected connectors) to be rotated a sufficient amount to
allow convenient access to the adapters without causing the minimum
bend radius of the associated optical fiber to be compromised by
engaging the back wall 14 or the like. FIG. 9 illustrates the
plurality of adapters 24 in a rotated position.
[0058] Turning now to the embodiment of FIG. 12, the FDT 110
includes similar pluralities of adapters 124, but with alternative
devices for allowing selective movement of the pluralities of
adapters. The pluralities of adapters 124 include a vertical bar
132 and a hinge 134; however, the latch 136 comprises an opening
for receiving a fastening device, such as a screw, nut/bolt
combination, wire tie, or the like. FIGS. 13 and 14 illustrate
rotation of the pluralities of adapters 124 about the hinge 134.
The FDT 110 of FIGS. 12-15 also includes two splice trays 150 that
are mounted to the base 112 to enable splicing an optical fiber of
the drop cable to a connectorized pigtail (the connector 128 is
part of the pigtail, which is not otherwise shown). The splice
trays are of the type described in the concurrently filed U.S.
patent application entitled "Fiber Optic Splice Trays" that is
assigned to the present assignee and the disclosure of which is
incorporated by reference in its entirety herein. The splice tray
150 of the illustrated embodiment includes a slot 152 to
selectively receive a tab 154 protruding from the back wall 114 of
the base 112 to enable selective mounting of the splice tray to the
base. Still further embodiments of the present invention comprise
alternative devices for mounting one or more splice trays to the
base. Still further embodiments of the present invention include
FDTs with splitter devices provided within the FDT and other fiber
optic hardware as desired.
[0059] FIG. 16 provides an enlarge view of the grommets 160 and 162
provided in the openings 20 of the FDT 10 of FIGS. 1-11, and also
provided on the FDT 110 of FIGS. 12-15. The grommet 160 comprises
twelve openings 164 for passage of twelve individual drop cables
(not shown), and the grommet 162 comprises twenty-four openings 164
for passage of twenty-four individual drop cables. The openings 164
include slots 166 so that the cables may be placed within in the
grommet without passing an end of the drop cable (which may or may
not have a connector attached to the end) through the hole, thus
making installation of the grommet more convenient. Alternative
embodiments of the present invention comprise alternative grommets
for generally sealing and retaining the openings in the base and/or
cover of the FDT that allow passage of the fiber optic cables.
[0060] FIGS. 17-20 illustrate a strain relief device 170 included
in certain embodiments of the present invention. The strain relief
device 170 is adapted for use with microstructured optical fibers,
as described more fully below, based upon the ability of such
fibers to withstand a greater compression without causing excessive
signal loss within the fiber. The strain relief device 170
comprises a body 172 with a generally cylindrical shape that
defines an axis generally aligned with the axis of the
microstructured optical fibers 174 to be strain relieved. Along the
perimeter of the body 172 are provided a plurality of slots 176
adapted to receive the microstructured optical fibers 174 (and any
tubes, cables, or other assemblies associated therewith) such that
a portion of the microstructured optical fibers is positioned
radially outward of the perimeter of the body. Once the
microstructured optical fibers are positioned within the slots 176
of the body 172, a compression device 178 is positioned around the
body 172 and the microstructured optical fibers 174 to apply a
force upon the microstructured optical fibers to strain relieve the
optical fibers. The body 170 defines a circumferential slot 180
adapted to receive the compression device 178. The slot 178 defines
at least one shoulder 182 to prevent axial movement of the
compression device 178. The compression device 178 of the
illustrated embodiment comprises a wire tie device; however,
further embodiments of the present invention comprise alternative
compression devices to retain and/or seal the optical fibers to the
strain relief device. As shown in FIG. 17, the FDT 10 or other
enclosure into which the strain relief device 170 is installed may
include a spring clip 184 mounted to a surface (such as the back
wall 14) to selectively retain the strain relief device relative to
the FDT or other enclosure. Further embodiments of the present
invention include alternative devices for retaining the strain
relief device relative to the fiber optic enclosure.
[0061] Turning now to FIGS. 21-24, the FDT 210 is yet another
embodiment of the present invention that provides selective optical
connectivity for connectorized optical fibers of a distribution
cable and connectorized optical fibers of drop cables. The FDT
comprises a base 212 defining a back wall 214 and a sidewall 216
extending outwardly from the back wall similar to the embodiment of
FIG. 1. The FDT 210 also includes a plurality of adapters 224
joined to the base 212, and includes a distribution cover 250
between the back wall 214 of the base 212 and the cover 222. The
distribution cover 250 is adapted to provide limited access to the
portion of the adapters 224 that receive a connector 226 of the
distribution cable. The distribution cover 250 of some embodiments
of the present invention includes a lock device, such as a fastener
with an uncommon feature, a padlock, or the like, to allow access
under the distribution cover to only limited individuals, such as
technicians working on behalf of the service provider, thus
preventing tampering with the optical connections by customers,
vandals, or others.
[0062] Although not shown in FIGS. 21-24, the FDT 210 includes
grommets or similar devices in the openings 218 and 220, and may
include a fanout positioned between the distribution cover and the
base to optically connect the optical fiber of the distribution
cable with the portion of the adapters that receive a connector 226
of the distribution cable. The plurality of adapters 224 of the FDT
210 are illustrated in a fixed position relative to the base 212 of
the FDT; however, further embodiments of the present invention may
include additional or alternative features to allow the plurality
of adapters to be moved as desired.
[0063] Turning now to FIGS. 25-38, an FDT in accordance with yet
another embodiment of the present invention is illustrated. The FDT
310 defines a generally curved top and front surface (on both the
cover 322 and sidewalls 316 of the base 312). The FDT 310 also
includes a bracket 332 that is selectively movable relative to the
base 312 and to which are joined two pluralities of adapters 324.
The bracket 332 is selectively removable from the base 312, as
shown in FIG. 26, and is selectively rotatable relative to the base
312, as shown in FIG. 27. The bracket 332 comprises a polymer or
other moderately flexible material to allow sufficient bending,
when a force is exerted upon the bracket by a technician with his
or hand or with a tool or the like, to cause the bracket 332 to
become detached at one or more attachment points. As shown in FIGS.
25-27, the bracket 332 is attached to the base 312 at four points
with pins 333a that are received in openings 333b on protrusions
from the base. Therefore, a technician can detach all four pins
333a to selectively remove the bracket 333, or detach the two top
pins 333a to selective rotate the bracket about a horizontal axis,
or the like. Further embodiments of the present invention include
additional brackets attached/detached by alternative devices that
may be removed and/or rotated in alternative directions.
[0064] The two pluralities of adapters 324 each define axes of the
adapters therein, and the FDT 310 of FIG. 25 includes pluralities
of adapters 324 that are slightly angled relative to one another to
enable convenient access to one or both sides of the adapters.
Further embodiments of the present invention include alternative
numbers of adapters at alternative relative positions and/or
orientations. As shown in FIGS. 28-32, the FDT 310 includes a cover
322 that is generally domed shape. The cover 322 of FIGS. 31 and 32
comprises a latch device 323a on each side of the cover generally
near the bottom of the cover to selectively retain the cover
relative the base. The base 312 of an FDT (as shown in FIG. 34) is
adapted to receive the cover 322 of FIGS. 31 and 32 includes an
opening 323b for each latch device 323a to selective receive the
latch device and retain the cover relative to the base.
[0065] Turning now to FIGS. 33 and 34, a top view of the sidewall
316 of the FDT 310 is provided. As can be seen, the opening 318 for
passage of the distribution cable (not shown) can include an
adapter 319a. The openings 320a for the drop cables may include
grommets 360 as shown in FIG. 33. Alternatively, as shown in FIG.
34, the openings 320b may define one or more slots adapted to allow
passage of two or more drop cables. The slot defines at least one
opened portion 320c sized to allow passage of the connector of the
drop cable, and the slot further defines other portions 320d and
320e sized to allow passage of the drop cable alone. Still further
embodiments of the present invention comprise alternative openings
and structures for providing secure and convenient passage of the
optical fibers and/or cables into the FDT.
[0066] Referring now to FIGS. 35 and 36, a strain relief device 370
is provided to strain relieve and seal a distribution cable through
an opening 318 within the FDT. The strain relief device comprises a
generally frustoconical device that includes three ribs 371 along
the frustoconical surface 373. The ribs 371 enable the strain
relief device 370 to be better retained within the opening 318 (as
compared to similar devices without ribs), and the frustoconical
surface 373 enables the strain relief device to be wedged within
the opening to provide a sufficient seal and/or sufficient strain
relief. The strain relief device 370 includes a slit along the
axial length of the strain relief device to provide convenient
receipt of the cable within the strain relief device. Still further
embodiments of the present invention include alternative strain
relief devices.
[0067] Various embodiments of the present invention are adapted to
include bend performance optical fibers. One example of bend
performance optical fiber is a microstructured optical fiber having
a core region and a cladding region surrounding the core region,
the cladding region comprising an annular hole-containing region
comprised of non-periodically disposed holes such that the optical
fiber is capable of single mode transmission at one or more
wavelengths in one or more operating wavelength ranges. The core
region and cladding region provide improved bend resistance, and
single mode operation at wavelengths preferably greater than or
equal to 1500 nm, in some embodiments also greater than about 1310
nm, in other embodiments also greater than 1260 nm. The optical
fibers provide a mode field at a wavelength of 1310 nm preferably
greater than 8.0 microns, more preferably between about 8.0 and
10.0 microns. In preferred embodiments, optical fiber disclosed
herein is thus single-mode transmission optical fiber.
[0068] In some embodiments of the present invention, the
microstructured optical fibers disclosed herein comprises a core
region disposed about a longitudinal centerline and a cladding
region surrounding the core region, the cladding region comprising
an annular hole-containing region comprised of non-periodically
disposed holes, wherein the annular hole-containing region has a
maximum radial width of less than 12 microns, the annular
hole-containing region has a regional void area percent of less
than about 30 percent, and the non-periodically disposed holes have
a mean diameter of less than 1550 nm.
[0069] By "non-periodically disposed" or "non-periodic
distribution", it is meant 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 holes are randomly
or non-periodically distributed across a portion of the fiber.
Similar cross sections taken at different points along the length
of the fiber will reveal different cross-sectional hole patterns,
i.e., various cross-sections will have different hole patterns,
wherein the distributions of holes and sizes of holes do not match.
That is, the holes are non-periodic, i.e., they are not
periodically disposed within the fiber structure. These holes are
stretched (elongated) along the length (i.e. in a direction
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.
[0070] For a variety of applications, it is desirable for the holes
to be formed such that greater than about 95% of and preferably all
of the holes exhibit a mean hole size in the cladding for the
optical fiber which is less than 1550 nm, more preferably less than
775 nm, most preferably less than 390 nm. Likewise, it is
preferable that the maximum diameter of the holes in the fiber be
less than 7000 nm, more preferably less than 2000 nm, and even more
preferably less than 1550 nm, and most preferably less than 775 nm.
In some embodiments, the fibers disclosed herein have fewer than
5000 holes, in some embodiments also fewer than 1000 holes, and in
other embodiments the total number of holes is fewer than 500 holes
in a given optical fiber perpendicular cross-section. Of course,
the most preferred fibers will exhibit combinations of these
characteristics. Thus, for example, one particularly preferred
embodiment of optical fiber would exhibit fewer than 200 holes in
the optical fiber, the holes having a maximum diameter less than
1550 nm and a mean diameter less than 775 nm, although useful and
bend resistant optical fibers can be achieved using larger and
greater numbers of holes. The hole number, mean diameter, max
diameter, and total void area percent of holes can all be
calculated with the help of a scanning electron microscope at a
magnification of about 800.times. and image analysis software, such
as ImagePro, which is available from Media Cybernetics, Inc. of
Silver Spring, Md., USA.
[0071] The optical fibers disclosed herein may or may not include
germania or fluorine to also adjust the refractive index of the
core and or cladding of the optical fiber, but these dopants can
also be avoided in the intermediate annular region and instead, the
holes (in combination with any gas or gases that may be disposed
within the holes) can be used to adjust the manner in which light
is guided down the core of the fiber. The hole-containing region
may consist of undoped (pure) silica, thereby completely avoiding
the use of any dopants in the hole-containing region, to achieve a
decreased refractive index, or the hole-containing region may
comprise doped silica, e.g. fluorine-doped silica having a
plurality of holes.
[0072] In one set of embodiments, the core region includes doped
silica to provide a positive refractive index relative to pure
silica, e.g. germania doped silica. The core region is preferably
hole-free. In some embodiments, the core region comprises a single
core segment having a positive maximum refractive index relative to
pure silica .DELTA..sub.1 in %, and the single core segment extends
from the centerline to a radius R1. In one set of embodiments,
0.30%<.DELTA..sub.1<0.40%, and 3.0 .mu.m<R1<5.0 .mu.m.
In some embodiments, the single core segment has a refractive index
profile with an alpha shape, where alpha is 6 or more, and in some
embodiments alpha is 8 or more. In some embodiments, the inner
annular hole-free region extends from the core region to a radius
R2, wherein the inner annular hole-free region has a radial width
W12, equal to R2-R1, and W12 is greater than 1 .mu.m. Radius R2 is
preferably greater than 5 .mu.m, more preferably greater than 6
.mu.m. The intermediate annular hole-containing region extends
radially outward from R2 to radius R3 and has a radial width W23,
equal to R3-R2. The outer annular region 186 extends radially
outward from R3 to radius R4. Radius R4 is the outermost radius of
the silica portion of the optical fiber. One or more coatings may
be applied to the external surface of the silica portion of the
optical fiber, starting at R4, the outermost diameter or outermost
periphery of the glass part of the fiber. The core region and the
cladding region are preferably comprised of silica. The core region
is preferably silica doped with one or more dopants. Preferably,
the core region is hole-free. The hole-containing region has an
inner radius R2 which is not more than 20 .mu.m. In some
embodiments, R2 is not less than 10 .mu.m and not greater than 20
.mu.m. In other embodiments, R2 is not less than 10 .mu.m and not
greater than 18 .mu.m. In other embodiments, R2 is not less than 10
.mu.m and not greater than 14 .mu.m. Again, while not being limited
to any particular width, the hole-containing region has a radial
width W23 which is not less than 0.5 .mu.m. In some embodiments,
W23 is not less than 0.5 .mu.m and not greater than 20 .mu.m. In
other embodiments, W23 is not less than 2 .mu.m and not greater
than 12 .mu.m. In other embodiments, W23 is not less than 2 .mu.m
and not greater than 10 .mu.m.
[0073] Such fiber can be made to exhibit a fiber cutoff of less
than 1400 nm, more preferably less than 1310 nm, a 20 mm macrobend
induced loss at 1550 nm of less than 1 dB/turn, preferably less
than 0.5 dB/turn, even more preferably less than 0.1 dB/turn, still
more preferably less than 0.05 dB/turn, yet more preferably less
than 0.03 dB/turn, and even still more preferably less than 0.02
dB/turn, a 12 mm macrobend induced loss at 1550 nm of less than 5
dB/turn, preferably less than 1 dB/turn, more preferably less than
0.5 dB/turn, even more preferably less than 0.2 dB/turn, still more
preferably less than 0.01 dB/turn, still even more preferably less
than 0.05 dB/turn, and a 8 mm macrobend induced loss at 1550 nm of
less than 5 dB/turn, preferably less than 1 dB/turn, more
preferably less than 0.5 dB/turn, and even more preferably less
than 0.2 dB-turn, and still even more preferably less than 0.1
dB/turn.
[0074] The fiber of some embodiments of the present invention
comprises a core region that is surrounded by a cladding region
that comprises randomly disposed voids which are contained within
an annular region spaced from the core and positioned to be
effective to guide light along the core region. Other optical
fibers and microstructured fibers may be used in the present
invention. Additional features of the microstructured optical
fibers of additional embodiments of the present invention are
described more fully in pending U.S. patent application Ser. No.
11/583,098 filed Oct. 18, 2006, and provisional U.S. patent
application Ser. Nos. 60/817,863 filed Jun. 30, 2006; 60/817,721
filed Jun. 30, 2006; 60/841,458 filed Aug. 31, 2006; and 60/841,490
filed Aug. 31, 2006; all of which are assigned to Corning
Incorporated and the disclosures of which are incorporated by
reference herein.
[0075] Many modifications and other embodiments of the invention
set forth herein will come to mind to one skilled in the art to
which the invention pertains having the benefit of the teachings
presented in the foregoing descriptions and the associated
drawings. Therefore, it is to be understood that the invention is
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
present invention cover the modifications and variations of this
invention 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.
* * * * *