U.S. patent application number 12/700128 was filed with the patent office on 2010-06-03 for fiber optic cables and assemblies and the performance thereof.
Invention is credited to John B. Johnson.
Application Number | 20100135629 12/700128 |
Document ID | / |
Family ID | 39323794 |
Filed Date | 2010-06-03 |
United States Patent
Application |
20100135629 |
Kind Code |
A1 |
Johnson; John B. |
June 3, 2010 |
FIBER OPTIC CABLES AND ASSEMBLIES AND THE PERFORMANCE THEREOF
Abstract
A fiber optic jumper assembly comprising at least one bend
performance 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, a protective covering positioned over the at least
one bend performance optical fiber, and at least one connector
mounted upon each end of the at least one bend performance optical
fiber. A preconnectorized fiber optic jumper assembly comprising a
microstrucutred fiber having a delta attenuation of 0.00 dB at 5
wraps about a 6 mm diameter at a reference wavelength of 1625
nm.
Inventors: |
Johnson; John B.;
(Taylorsville, NC) |
Correspondence
Address: |
CORNING INCORPORATED
INTELLECTUAL PROPERTY DEPARTMENT, SP-TI-3-1
CORNING
NY
14831
US
|
Family ID: |
39323794 |
Appl. No.: |
12/700128 |
Filed: |
February 4, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11638610 |
Dec 13, 2006 |
7680380 |
|
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12700128 |
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Current U.S.
Class: |
385/126 |
Current CPC
Class: |
G02B 6/0365 20130101;
G02B 6/02366 20130101 |
Class at
Publication: |
385/126 |
International
Class: |
G02B 6/036 20060101
G02B006/036 |
Claims
1. A fiber optic jumper assembly, comprising: at least one bend
performance optical fiber comprising a core region, a hole-free
inner annular cladding region surrounding the core region, an
annular hole-containing cladding region surrounding the inner
annular cladding region and comprised of non-periodically disposed
holes, and an outer hole-free cladding region surrounding the
annular hole-containing cladding region; a protective covering
positioned over the at least one bend performance optical fiber;
and at least one connector mounted upon at least one end of the at
least one bend performance optical fiber.
2. The jumper assembly of claim 1, wherein the jumper assembly has
a delta attenuation of 0.11 dB or less at one turn about a 10 mm
diameter structure at a reference wavelength of 1625
nanometers.
3. The jumper assembly of claim 1, wherein the jumper assembly has
a delta attenuation of 0.93 dB or less at five turns about a 10 mm
diameter structure at a reference wavelength of 1625
nanometers.
4. The jumper assembly of claim 1, wherein the jumper assembly has
a delta attenuation of 0.46 dB or less at one turn about a 6 mm
diameter structure at a reference wavelength of 1625
nanometers.
5. The jumper assembly of claim 1, wherein the jumper assembly has
a delta attenuation of 3.12 dB or less at five turns about a 6 mm
diameter at a reference wavelength of 1625 nanometers.
6. The jumper assembly of claim 1, wherein the at least one bend
performance optical fiber has a 12 mm macrobend induced loss at
1550 nm of less than 0.1 dB/turn.
7. The jumper assembly of claim 1, wherein the at least one bend
performance optical fiber has a 12 mm macrobend induced loss at
1550 nm of less than 0.05 dB/turn.
8. The jumper assembly of claim 1, wherein the at least one bend
performance optical fiber has an 8 mm macrobend induced loss at
1550 nm of less than 0.2 dB/turn.
9. The jumper assembly of claim 1, wherein the at least one bend
performance optical fiber has an 8 mm macrobend induced loss at
1550 nm of less than 0.1 dB/turn.
10. A fiber optic assembly for performing interconnections within a
fiber optic network, the assembly comprising: at least one
microstructured optical fiber having an outer surface and
comprising a core region that is surrounded by a cladding region
that comprises randomly disposed cladding material voids that are
contained within an annular region spaced from the core and outer
surface respectively by a hole-free inner and outer cladding
regions, the void-containing annular region having a radial width
W23 in the range from 0.5 um to 20 .mu.m; a protective covering
surrounding at least a portion of the at least one microstructured
optical fiber; and at least one connector mounted upon at least one
end of the at least one microstructured optical fiber.
11. The fiber optic assembly of claim 10, wherein the assembly has
a delta attenuation of 0.11 dB or less when wrapped one turn about
a 10 mm diameter structure at a reference wavelength of 1625
nm.
12. The fiber optic assembly of claim 10, wherein the assembly has
a delta attenuation of 0.46 or less when wrapped one turn about a 6
mm diameter structure at a reference wavelength of 1625 nm.
13. The fiber optic assembly of claim 10, wherein the assembly has
a delta attenuation of 0.00 when wrapped 5 turns about a 6 mm
diameter structure at a reference wavelength of 1625 nm.
14. The fiber optic jumper assembly of claim 1, wherein the core
region has a radius R1 in the range from 1 .mu.m to 5 .mu.m, the
inner annular cladding region has an inner radius R2 in the range
from 10 .mu.m to 20 .mu.m, and the annular hole-containing cladding
region has an annular width W23 in the range from 0.5 .mu.m to 20
.mu.m.
15. The fiber optic assembly of claim 10, wherein the core region
has a radius R1 in the range from 1 .mu.m to 5 .mu.m, the inner
annular cladding region has an inner radius R2 in the range from 10
.mu.m to 20 .mu.m.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional of U.S. Ser. No. 11/638,610
filed Dec. 13, 2006, the entire content of which is hereby
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to fiber optic
cables and jumper assemblies and the performance thereof. By way of
example, the invention is related to assemblies such as optical
fiber jumpers having at least one bend performance optical fiber,
thereby enabling previously unattainable optical performance
characteristics.
BACKGROUND OF THE INVENTION
[0003] Along with the increase in the deployment of
"Fiber-to-the-Premises" (FTTP) optical networks, a need has arisen
for increasing the performance, manageability, handleability and
flexibility of fiber optic cables, cable assemblies and network
components in general. With respect to outdoor installation
environments, cables, cable assemblies and other network components
are being developed that are more easily interconnected and
installed within their environment, such as within aerial
installation environments or through small diameter conduit. With
respect to indoor environments and multi-dwelling units, cables,
cable assemblies, connection terminals and other network components
are being developed to improve installation aesthetics and handle
the interconnection of an increasing number of subscribers. Within
both environments, it would be desirable to develop components that
perform better, are more flexible to installation stresses and are
more robust and long lasting, thus saving time and costs.
[0004] Conventional cables, cable assemblies, fiber optic hardware
and other network components typically define structure that
accommodates, and is in part, limited by the physical
characteristics of the optical fibers contained therein. In other
words, it is oftentimes the case that the physical and performance
limitations of the optical fibers partly define assembly structure
and processes associated with manufacturing said assemblies. Thus,
optical fibers are one limiting factor in the evolution of fiber
optic networks.
[0005] Accordingly, what is desired are fiber optic cables and
jumper assemblies that include bend performance optical fiber
having improved bending performance characteristics over
conventional cables and assemblies. It would be desirable to
provide cables and jumper assemblies capable of being significantly
bent or wrapped, either stand-alone or around network structure,
without suffering appreciable loss. Such cables and assemblies
including bend performance fiber would be more accepting of
handling without damage.
BRIEF SUMMARY OF THE INVENTION
[0006] To achieve the foregoing and other objects, and in
accordance with the purposes of the invention as embodied and
broadly described herein, the present invention provides various
embodiments of fiber optic cables, jumpers and other assemblies
including bend performance optical fiber in at least a portion
thereof. The present invention further provides bend performance
optical fiber suitable for use in fiber optic cables, fiber optic
hardware and other assemblies, wherein the bend performance optical
fiber comprises certain physical and performance characteristics
that lends itself to reduced component size, tighter bend radius
tolerances without degraded performance, and relaxes fiber routing
and handling requirements.
[0007] In one embodiment, the bend performance optical fiber of the
present invention is 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 or voids, such that
the optical fiber is capable of single mode transmission at one or
more wavelengths in one or more operating wavelength ranges. The
non-periodically disposed holes are randomly or non-periodically
distributed across a portion of the fiber. The holes may be
stretched (elongated) along the length (i.e. in a direction
generally parallel to the longitudinal axis) of the optical fiber,
but may not extend the entire length of the entire fiber for
typical lengths of transmission fiber.
[0008] In other embodiments, the bend performance fiber of the
present invention may comprise at least a portion of fiber optic
cables, fiber optic cable assemblies, network connection terminals,
fiber optic hardware or any other fiber optic network component
including at least one optical fiber maintained therein, routed
therein or routed therethrough.
[0009] Additional features and advantages of the invention will be
set forth in the detailed description which follows, and in part
will be readily apparent to those skilled in the art from that
description or recognized by practicing the invention as described
herein, including the detailed description which follows, the
claims, as well as the appended drawings.
[0010] It is to be understood that both the foregoing general
description and the following detailed description present
exemplary embodiments of the invention, and are intended to provide
an overview or framework for understanding the nature and character
of the invention as it is claimed. The accompanying drawings are
included to provide a further understanding of the invention, and
are incorporated into and constitute a part of this specification.
The drawings illustrate various embodiments of the invention, and
together with the detailed description, serve to explain the
principles and operations thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] These and other features, aspects and advantages of the
present invention are better understood when the following detailed
description of the invention is read with reference to the
accompanying drawings, in which:
[0012] FIG. 1 is a schematic diagram illustrating a cross-section
of a bend performance optical fiber operable in accordance with an
exemplary embodiment of the present invention;
[0013] FIG. 2 is a cross-sectional image of a microstructured bend
performance optical fiber illustrating an annular hole-containing
region comprised of non-periodically disposed holes;
[0014] FIG. 2a is a cross-sectional image of a fiber optic cable
using the microstructured bend performance optical fiber of FIG. 1
according to the present invention;
[0015] FIG. 2b is a cross-sectional image of another fiber optic
cable using the microstructured bend performance optical fiber of
FIG. 1 according to the present invention;
[0016] FIG. 2c is a plan view of the fiber optic cable of FIG. 2a
being bent in an aggressive manner to demonstrate a minimum bend
radius;
[0017] FIG. 3 illustrates one embodiment of an optical fiber jumper
assembly using microstructured bend performance optical fiber of
FIG. 1 completing about one turn about a small diameter
structure;
[0018] FIG. 4 illustrates the optical fiber jumper assembly of FIG.
3 completing multiple turns about a structure;
[0019] FIG. 5 illustrates the optical fiber jumper assembly of FIG.
3 shown tied in a knot;
[0020] FIG. 6 illustrates a portion of an optical fiber jumper
assembly including bend performance fiber bent about 90 degrees
around generic network structure; and
[0021] FIG. 7 illustrates a portion of an optical fiber jumper
assembly including bend performance fiber bent about 180 degrees
around generic network structure.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings in which
exemplary embodiments of the invention are shown. However, the
invention may be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. These
exemplary embodiments are provided so that this disclosure will be
both thorough and complete, and will fully convey the scope of the
invention and enable one of ordinary skill in the art to make, use
and practice the invention. Like reference numbers refer to like
elements throughout the various drawings.
[0023] FIG. 1 depicts a representation of a bend performance
optical fiber 1 suitable for use in fiber optic cables, cables
assemblies, fiber optic hardware and other network components of
the present invention. The present invention is advantageous
because it permits assemblies having aggressive
bending/installation solutions while optical attenuation remains
extremely low. As shown, bend performance optical fiber 1 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.
[0024] In some embodiments, 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.
[0025] By "non-periodically disposed" or "non-periodic
distribution", 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 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.
[0026] 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.
[0027] 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.
[0028] 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. As illustrated in FIG. 1, in some embodiments, the core
region 170 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 R.sub.1. In one set of embodiments,
0.30%<.DELTA..sub.1<0.40%, and 3.0 .mu.m
.mu.m<R.sub.1<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 182 extends
from the core region to a radius R.sub.2, 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 184 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 170 and the cladding region 180 are
preferably comprised of silica. The core region 170 is preferably
silica doped with one or more dopants. Preferably, the core region
170 is hole-free. The hole-containing region 184 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 184 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.
[0029] 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.
[0030] An example of a suitable fiber is illustrated in FIG. 2. The
fiber in FIG. 2 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 description of microstructured fibers
used in the present invention are disclosed 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 incorporated herein by reference.
[0031] Optical fiber cables of the present invention allow
aggressive bending such as for installation, slack storage, and the
like while inhibiting a bend radii that allows damage and/or breaks
the optical fiber. FIG. 2a shows a cross-sectional view of
explanatory fiber optic cable 100 having optical fiber 1 within a
protective covering 8. Generally speaking, optical fiber 1 is
maintained within at least one protective covering such as a buffer
layer and/or a jacket and is referred to herein as a "fiber optic
cable". As shown, protective covering 8 includes a buffer layer 8a
disposed about optical fiber 1 and a jacket 8b. Additionally, fiber
optic cable 100 also includes a plurality of optional strength
members 14 disposed between buffer layer 8a and jacket 8b. Strength
members 14 can also include a water-swellable component for
blocking the migration of water along the fiber optic cable. FIG.
2b depicts an alternate fiber optic cable 100' that is similar to
fiber optic cable 100, but it does not include strength members and
consequently has a smaller outer diameter such as about 4
millimeters if the jacket wall thickness remains the same.
Additionally, since the strength members are omitted it is possible
to remove the buffer layer and jacket from the fiber optic cable in
a single step. Other fiber optic cables and/or other assembly
designs are also possible according to the concepts of the
invention. By way of example, variations of fiber optic cables 100
and 100' can be preconnectorized with a connector for plug and play
connectivity. For instance, fiber optic cables can include a
hardened plug and connector such as an Opti-Tap or Opti-Tip
available from Corning Cable Systems of Hickory, N.C.
[0032] Protective covering 8 uses a bend radius control mechanism
for protecting the optical fiber by inhibiting damage and/or
breaking of the optical fiber as the fiber optic cable is bent into
small bend radii while still providing a highly flexible fiber
optic cable design. In other words, the bend radius control
mechanism maintains a minimum bend radii for the optical fiber so
damage and/or breaking is avoided. By way of example, fiber optic
cable 100 can be tied in a knot, bent about small structures, and
the like while having extremely low optical attenuation; however,
the fiber optic cable still should prevent damage and/or breaking
of the optical fiber during these installations. Previously,
conventional fiber optic cables would have high optical attenuation
or go dark before breaking the optical fiber was a concern, thus
the craft avoided using small bend radii for preserving optical
performance. One benefit of the present invention is that the fiber
optic cable designs are suitable for rugged installations both by
the craft and untrained individuals.
[0033] Robustness of the fiber optic cable design is accomplished
by suitable coupling with the protective covering for inhibiting
buckling of the optical fiber within the same. Additionally,
maintaining coupling between jacket 8b and strength members 14
inhibits the transfer of tensile forces to optical fiber 1.
Coupling is accomplished using a pressure extrusion process and can
allow aggressive bending of the fiber optic cable while maintaining
a suitable coupling level. Consequently, the coupling results in
very little to no construction stretch for the strength members. As
used herein, construction stretch means that all of the cable
components are not simultaneously stretched when applying a tensile
force to the fiber optic cable. Illustratively, a fiber optic cable
exhibiting construction stretch typically has the jacket and
optical fiber supporting the initially applied tensile force, but
the strength members do not. Thus, as the jacket and optical fiber
are stretched to a point where the slack in the strength members is
removed and the strength members also begin to support the load.
This construction stretch is problematic since it initially allows
the optical fiber to strain, which limits the ultimate tensile
strength of the fiber optic cable. Additionally, after the tensile
force is removed from the fiber optic cable the jacket stretched
before the optical fiber, thereby allowing buckling and/or
compression of the optical fiber within the fiber optic cable that
can cause optical losses. Any suitable type of material may be used
for protective covering 8 such as polyurethanes (PU),
polyvinylchloride (PVC), polyethylenes (PE), polyproplyenes (PP),
UV curable materials, etc. depending on the desired construction
and characteristics. Additionally, protective coverings 8 can use
flame-retardant materials such as a flame-retardant PVC or the like
as known in the art. Desirably, fiber optic cables of the invention
uses highly-flexible and robust designs that allow aggressive
bending of the cable while maintaining a minimum bend radii.
[0034] More specifically, fiber optic cable 100 is designed so that
it is highly flexible, maintains a minimum bend radius to inhibit
breaking of the optical fiber when aggressively bent, and have
enough coupling between protective covering 8 and optical fiber 1
to inhibit buckling of the optical fiber within protective covering
8. By way of example, fiber optic cable 100 includes optical fiber
1 having a plenum-grade buffer layer 8a with an outer diameter of
about 900 microns. Other types of materials, sizes, shapes, etc are
also possible for the buffer layer. Thereafter, four strength
members 14 were run in a parallel configuration (i.e., no
stranding) about the buffered optical fiber before jacket 8b was
applied. Eliminating stranding of strength members 14 is also
advantageous since it allows for increased line speeds. Jacket 8b
was pressure extruded using a PU material available from Huntsman
available under the tradename Irogran A78 P 4766. The jacket
material used had a relatively high ultimate elongation (i.e.,
elongation before breaking) measured according to DIN 53504 (a
German measurement standard), thereby providing a highly flexible
fiber optic cable design. Jackets for fiber optic cables of the
invention have an ultimate elongation that is about 500% or greater
such as about 600% or greater, and even about 700% or greater. The
PU jacket material used had an ultimate elongation of about 800%
along with a 300% tensile modulus of about 8.0 MPa. Additionally,
jacket 8b had an outer diameter of about 5 millimeters with an
inner diameter of about 1.7 millimeters. Consequently, fiber optic
cable 100 had an excellent flexibility while still inhibiting
breaking of the optical fiber when aggressively bent for instance
when fiber optic cable is bent like a hairpin as shown in FIG. 2c
the bend radius control mechanism is provided by jacket 8b along
with its coupling characteristics. In other words, the bend radius
control mechanism of jacket 8b provides a minimum bend diameter of
about 5 millimeters (e.g., about two times the radius of the fiber
optic cable) for inhibiting breaking of the optical fiber when bent
as shown in FIG. 2c. Using the bend radius control mechanism also
improves crush performance of the fiber optic cable since the
jacket is relatively thick and highly flexible. Furthermore, the
optical performance of fiber optic cable 100 during aggressive
bendng is impressive compared with conventional fiber optic
cables.
[0035] To test the optical performance of fiber optic cable 100, a
corner bend test was conducted as described below. The corner bend
test routed a portion of fiber optic cable 100 over a 90 degree
edge (i.e., nearly a zero bend radius) and weights were hung from
the fiber optic cable to apply a constant force at the bend while
measuring a delta attenuation (e.g., change in attenuation) at a
reference wavelength of 1625 nanometers due to the applied force.
The corner bend test used fiber optic cable 100 and a similar fiber
optic cable design using a SMF28-e optical fiber available from
Corning, Inc. The results for the corner bend test are summarized
in Table 1 below.
TABLE-US-00001 TABLE 1 Corner Bend Test Fiber Optic Conventional
Cable 100 Cable Delta Delta Attenuation (dB) Attenuation (dB) 1310
1550 1625 1310 1550 1625 Load (kg) nm nm nm nm nm nm 0 0.00 0.00
0.00 0.00 0.01 0.02 0.6 1.16 3.16 5.21 0.01 0.02 0.04 1 2.51 8.14
11.06 0.01 0.06 0.09 5 -- -- -- 0.03 0.18 0.22 10 -- -- -- 0.03
0.15 0.22
[0036] As depicted in Table 1, the conventional cable had elevated
levels of delta attenuation at all wavelengths with a load of 0.6
kilograms. Moreover, the delta attenuation was so high above a load
of 1 kilogram that measurements were not taken. On the other hand,
fiber optic cable 100 had low delta attenuation values with loads
up to 10 kilograms. By way of example, fiber optic cable 100 had a
delta attenuation of about 0.1 dB or less for the corner bend test
with a load of 1 kilogram at a reference wavelength of 1625
nanometers. Other testing was also performed such as bending fiber
optic cable 100 about a mandrel with a given diameter along with a
conventional fiber optic cable for comparison purposes. More
specifically, a delta attenuation (dB) for the loss was measured
after wrapping a predetermined number of turns (i.e., each turn is
about 360 degrees) of fiber optic cable around a mandrel with a
given diameter.
TABLE-US-00002 TABLE 2 Mandrel Wrap Test at a Reference Wavelength
of 1625 nanometers Conventional Cable Fiber Optic Cable 100 Delta
Attenuation (dB) Delta Attenuation (dB) Number of 4.6 mm 7.5 mm 15
mm 4.6 mm 7.5 mm 15 mm Turns mandrel mandrel mandrel mandrel
mandrel mandrel 0 -- -- 0.00 0.00 0.00 0.00 1 -- -- 3.10 0.39 0.10
0.07 2 -- -- 7.96 0.56 0.18 0.11 3 -- -- 11.58 0.83 0.33 0.17 4 --
-- 16.03 1.18 0.53 0.23 5 -- -- 20.19 1.43 0.68 0.23
[0037] As depicted in Table 2, the conventional cable had elevated
levels of delta attenuation when it was wrapped about a 15
millimeter mandrel. Moreover, the delta attenuation was so large
with mandrels smaller than 15 millimeters that the measurements
were not taken. On the other hand, fiber optic cable 100 had delta
attenuation values that were more than an order of magnitude lower
using a 15 millimeter mandrel. By way of example, fiber optic cable
100 had a delta attenuation of about 0.33 dB or less when wrapped 3
turns about a 7.5 millimeter mandrel at a reference wavelength of
1625 nanometers.
[0038] Another example of assemblies useful with the concepts of
the present invention are optical fiber jumper assemblies that are,
generally speaking, used within structures for interconnection
purposes. FIGS. 3-5 depict an explanatory optical fiber jumper
assembly 15 (hereinafter "jumper assembly") using optical fiber 1
and is shown in various configurations to illustrate physical and
performance capabilities of assemblies according to the concepts of
the invention. Moreover, jumper assemblies represented by jumper
assembly 15 were tested for optical performance and compared with
conventional jumper assemblies as presented below. Jumper
assemblies of the invention preserve optical attenuation during,
for example, macrobending down to levels not previously attainable
with previous constructions.
[0039] As shown, jumper assembly 15 is connectorized at each end
using SC connectors 12, such as those available from Coining Cable
Systems of Hickory, N.C., using techniques known in the art. Of
course, jumper assemblies may include any length of fiber optic
cable, type of connector and/or number of optical fibers capable of
performing interconnections within an optical network. It is
envisioned that a jumper assembly may be connectorized at each end
using similar or dissimilar connector types such as LC, FC, MT,
MTP, among others. The jumper assembly 15 may be aggressively bent,
either stand-alone or about network structure, such as for
installation, slack storage and routing without suffering
appreciable attenuation and without damage and/or breaks to the
optical fiber. The at least one optical fiber 1 is within a
protective covering 10 such as, but not limited to, a coating, a
buffer, or a jacket. In one example, the fiber 1 may be upjacketed
to about 500 um or about 900 um. The jumper assembly may further
include strength members, such as aramid strength members, as is
commonly known in the art. Other fiber optic jumper assemblies are
also possible according to the concepts of the invention.
[0040] The protective covering 10 may be made from material
including bend radius control properties for protecting the at
least one optical fiber within by inhibiting damage and/or breaking
of the optical fiber as the jumper assembly is bent into small bend
radii while still providing a highly flexible juniper design. By
way of example, the jumper assembly 15 can be tied in a knot, bent
about small structures, and the like while having extremely low
optical attenuation.
[0041] Referring specifically to FIG. 3, jumper assembly 15 is
shown completing one turn or wrap about a mandrel 14. Mandrel 14 is
shown to provide a guide for bending jumper assembly 15 about a
structure, and generically mandrel 14 represents a portion of
network structure about which the jumper assembly is installed
(e.g., a network interface device (NID), a cabinet, routing guide,
connector housing, connector port or the like). Mandrel 14 defines
a diameter, for example, the diameter is about 10 millimeters or
about 6 millimeters, but other sizes are possible. Referring
specifically to FIG. 4, jumper assembly 15 is shown wrapped about
the mandrel 14 and completing about five turns. Referring
specifically to FIG. 5, jumper assembly 15 is shown tied in a
knot.
[0042] Table 3 details optical performance data for different fiber
optic cable designs at a reference wavelength of 1625 nanometers.
More specifically, a delta attenuation (dB) for the loss was
measured after wrapping a predetermined number of turns (i.e., each
turn is about 360 degrees) of fiber optic cable around a mandrel
with a given diameter. Table 3 depicts the results for two
different single fiber cable (SFC) designs (i.e., a 2.0 millimeter
SFC and a 2.9 millimeter SFC) that were used as a portion of the
tested jumper assemblies. Each of the SFC designs used a
conventional optical fiber and a microstructured bend performance
optical fiber, thereby resulting in four jumper assemblies for
testing. Additionally, two different microstructured bend
performance optical fibers were used in the jumper assemblies of
the present invention to compare performance, listed in the table
below as Type I and Type II bend performance fibers. The
conventional optical fiber used in the conventional jumper
assemblies was a SMF-28e optical fiber available from Corning
Incorporated of Corning, N.Y. Both the 2.0 millimeter and the 2.9
SFC designs included an optical fiber having a 900 micron buffer
layer thereon that was surrounded by a plurality of aramid strength
members and a jacket. The differences between the 2.0 millimeter
and 2.9 millimeter SFC include the jacket wall thickness (e.g.,
respectively about 0.33 millimeters and about 0.45 millimeters) and
the quantity of aramid used.
TABLE-US-00003 TABLE 3 Delta Attenuation (dB) at 1625 nanometers
after Wrapping Around a Mandrel Delta At- Delta Delta Delta
tenuation Mandrel Attenuation Attenuation Attenuation 2.9 mm
Diameter - # Conventional Conventional 2.0 mm SFC SFC of Turns 2.0
mm SFC 2.9 mm SFC Type I Type II 10 mm - 1 Turns 25.42 dB 27.20 dB
0.11 dB 0.00 dB 10 mm - 2 Turns 41.30 dB 42.30 dB 0.27 dB 0.00 dB
10 mm - 3 Turns 45.00 dB 45.00 dB 0.42 dB 0.00 dB 10 mm - 4 Turns
45.89 dB 45.80 dB 0.70 dB 0.00 dB 10 mm - 5 Turns 46.20 dB 46.20 dB
0.93 dB 0.00 dB 6 mm - 1 Turns 46.20 dB 46.00 dB 0.46 dB 0.00 dB 6
mm - 2 Turns 46.20 dB 46.00 dB 0.98 dB 0.00 dB 6 mm - 3 Turns 46.20
dB 46.00 dB 1.70 dB 0.00 dB 6 mm - 4 Turns 46.20 dB 46.00 dB 2.72
dB 0.00 dB 6 mm - 5 Turns 46.20 dB 46.00 dB 3.12 dB 0.00 dB 90
degree bend 0.86 dB 0.53 dB 0.03 dB 0.00 dB
[0043] As depicted in Table 3, the conventional SFC jumpers had
elevated levels of delta attenuation at all turns about both
mandrel diameters. In comparison, the jumper assemblies including
both Type I and II fiber had delta attenuation orders of magnitude
lower, and with respect to the jumper assembly including Type II
bend performance fiber, there was no delta attenuation at all turns
about each mandrel diameter. Further, both the conventional and
Type I and II jumper assemblies were bent about a 90 degree bend,
such as a corner bend test, and the jumper assemblies including
bend performance fiber outperformed the conventional jumpers. By
way of example, the jumper assembly 15 including bend performance
fiber had a delta attenuation of about 0.03 dB or less for the 90
degree bend test at a reference wavelength of 1625 nanometers.
[0044] Bend performance fibers of the present invention may be
included within various cable types and cable assemblies to achieve
highly flexible cables to facilitate installation and require less
skill in handling. The cables and cable assemblies described herein
may be installed within fiber optic hardware such as local
convergence points for multi-dwelling units, cross-connect frames
and modules, and surface, pad and pole mounted local convergence
points showing smaller size and higher density. Referring to FIGS.
6-7, a portion of the jumper assembly with the protective covering
10 is shown wrapped around generic network structure 20. An angle
theta 22 corresponds to a portion of a turn about the generic
structure 20. Generic structure 20 may include, but is not limited
to, structure of fiber optic cable assemblies, hardware, spools,
thru holes, connector ports, routing guides, cabinets or any other
structure within the network.
[0045] The foregoing is a description of various embodiments of the
invention that are given here by way of example only. Although
fiber optic cables and jumper assemblies including bend performance
fiber in at least a portion thereof have been described with
reference to preferred embodiments and examples thereof, other
embodiments and examples may perform similar functions and/or
achieve similar results. All such equivalent embodiments and
examples are within the spirit and scope of the present invention
and are intended to be covered by the appended claims.
* * * * *