The present disclosure relates to the field of optical fibre cable and, in
particular, relates to an optical fibre cable for aerial applications.
BACKGROUND
[0002] Over the last few decades, the need for laying overhead cables has
increased rapidly due to the advancement in optical networks. The overhead cables are laid to reduce load on pipeline resources and reduce cost of laying cables. The overhead cables include optical fiber cables used for aerial applications, thus known as aerial drop optical fiber cables. The aerial drop optical fiber cables are typically used for fiber to the home application. The aerial drop optical fiber cables are compact in structure and has a layer stranded structure.
[0003] The aerial drop optical fiber cables include multiple number of tubes
with each tube having multiple number of optical fibers. In addition, the aerial drop optical fiber cables need to have a pre-defined break load in order to be installed aerially complying with the safety standards. So, a proper choice of cable components is very crucial for developing these cables. The tubes used in the conventional cables are made of materials such as Polypropylene and Polybutylene Terephthalate. However, these cables with tubes made of such materials may not meet the required breakload requirements.
[0004] There are a few prior art references which talk about aerial drop
cables. One such reference CN113419319A discloses an aerial drop optical fiber cable having an optical fiber ribbon array surrounded by a water blocking layer and an outer jacket. Another such reference JP2004117867A

discloses an optical fiber cable with optical fiber positioned inside a storage
section and strength members embedded in the sheath. Yet another reference
CN111580233A discloses an optical fiber cable comprising a cable core and
an outer sheath and is characterized in that the cable core is formed by
twisting optical fiber bundles. However, CN113419319A and
JP2004117867A talk about drop cables and lay-length of fiber ribbons inside core but not about the lay length of the tubes. In addition, the reference CN111580233A does not talk lay length of the fibers and the tubes.
[0005] In light of the above-stated discussion, there exists a need for an
optical fibre cable for aerial application with optimized construction parameters and pre-defined break load that overcomes the above cited drawbacks of the conventional optical fibre cable.
OBJECT OF THE DISCLOSURE
[0006] A primary object of the present disclosure is to provide an optical
fibre cable for aerial applications with optimized tube length.
[0007] Yet another object of the present disclosure is to provide the optical
fiber cable with reduced diameter suitable for aerial drop applications.
[0008] Yet another object of the present disclosure is to provide the aerial
drop optical fiber cable with low optical attenuation.
SUMMARY

[0009] In an aspect, the present disclosure provides an optical fibre cable.
The optical fibre cable includes one or more tubes, a sheath and one or more strength members. Each of the one or more tubes encloses at least one optical fiber. The one or more tubes have a tube length greater than a cable length. The one or more tubes have a young's modulus of less than or equal to 700 N. The one or more tubes have a lay-length of equal to or more than 400 mm. The sheath surrounds the one or more tubes. The one or more strength members are at least partially embedded in the sheath. The optical fiber cable breaks at a pre-defined load. The at least one optical fiber has a diameter of 200±20um. The at least one optical fiber have a macrobend loss of less than or equal to 0.75 dB/turn at 1550 nm when the at least one optical fiber is bent around a mandrel of 10mm radius.
STATEMENT OF THE DISCLOSURE
[0010] The present disclosure provides an optical fibre cable. The optical
fibre cable includes one or more tubes, a sheath and one or more strength members. Each of the one or more tubes encloses at least one optical fiber. The one or more tubes have a tube length greater than a cable length. The one or more tubes have a young's modulus of less than or equal to 700 N. The one or more tubes have a lay-length of equal to or more than 400 mm. The sheath surrounds the one or more tubes. The one or more strength members are at least partially embedded in the sheath. The optical fiber cable breaks at a pre-defined load. The at least one optical fiber has a diameter of 200±20um. The at least one optical fiber have a macrobend loss of less than or equal to 0.75 dB/turn at 1550 nm when the at least one optical fiber is bent around a mandrel of 10mm radius.

BRIEF DESCRIPTION OF THE FIGURES
[0011] 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 wherein:
[0012] FIG. 1 illustrates an optical fibre cable for aerial applications, in
accordance with an aspect of the present disclosure; and
[0013] FIG. 2 illustrates another optical fiber cable for aerial applications, in
accordance with another aspect of the present disclosure.
[0014] It should be noted that the accompanying figures are intended to
present illustrations of exemplary aspects of the present disclosure. These figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.

DETAILED DESCRIPTION
[0015] Reference in this specification to "one aspect" means that a particular
feature, structure, or characteristic described in connection with the aspect is included in at least one aspect of the present technology. The appearance of the phrase "in one aspect" in various places in the specification are not necessarily all referring to the same aspect, nor are separate or alternative aspects mutually exclusive of other aspects. Moreover, various features are described which may be exhibited by some aspects and not by others. Similarly, various requirements are described which may be requirements for some aspects but no other aspects.
[0016] Reference will now be made in detail to selected aspects of the
present disclosure in conjunction with accompanying figures. The aspects described herein are not intended to limit the scope of the disclosure, and the present disclosure should not be construed as limited to the aspects described. This disclosure may be embodied in different forms without departing from the scope and spirit of the disclosure. It should be understood that the accompanying figures are intended and provided to illustrate aspects of the disclosure described below and are not necessarily drawn to scale. In the drawings, like numbers refer to like elements throughout, and thicknesses and dimensions of some components may be exaggerated for providing better clarity and ease of understanding.
[0017] Moreover, although the following description contains many specifics
for the purposes of illustration, anyone skilled in the art will appreciate that many variations and/or alterations to said details are within the scope of the present technology. Similarly, although many of the features of the present technology are described in terms of each other, or in conjunction with each other, one skilled in the art will appreciate that many of these features can be provided independently of other features. Accordingly, this description of the

present technology is set forth without any loss of generality to, and without imposing limitations upon, the present technology.
[0018] It should be noted that the terms "first", "second", and the like, herein
do not denote any order, ranking, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.
[0019] FIG. 1 illustrates an optical fibre cable 100 for aerial applications, in
accordance with an aspect of the present disclosure. FIG. 2 illustrates another optical fiber cable 200 for aerial applications, in accordance with another aspect of the present disclosure. The optical fiber cable 100 is used for telecommunication applications and networking applications. The optical fiber cable 100 can be installed aerially and used for fiber to the home applications (FTTH). The optical fiber cable 100 adopts a layer stranded optical cable structure. The layer stranded optical cable structure includes optical fibers enclosed inside loose tubes and a water absorbing or blocking compound filled inside the loose tubes.
[0020] The optical fiber cable 100 is a work safe optical fiber cable. In
addition, the optical fiber cable 100 has a pre-defined breaking load. The pre-defined breaking load is needed in order for the optical fiber cable 100 to be installed aerially and comply with safety standards. The optical fiber cable 100 includes elements which have properties different from elements made of conventional materials. The properties of the elements of the optical fiber cable 100 are changed in order for the optical fiber cable 100 to be installed aerially and possess the pre-defined breaking load. The breaking load is defined as tension steadily applied on an element which is just sufficient to break or rupture the element.

[0021] The optical fiber cable 100 has a reduced diameter suitable for aerial
drop applications. In addition, the optical fiber cable 100 has low optical attenuation. Further, the optical fiber cable 100 has low Young's modulus of tubes which enables easy installation. The optical fibre cable 100 includes one or more tubes 104, a sheath 106 and one or more strength members 108. Each of the one or more tubes 104 encloses at least one optical fiber 102. In an aspect of the present disclosure, the optical fiber cable 100 includes a first layer 110. In general, an optical fiber cable includes a plurality of fibers and carries information in the form of data between two places using light technology. The optical fiber cable 100 is a cable used for carrying light over long distances. Furthermore, the optical fiber cable 100 may simply be used to transmit optical signals (which may carry sensor data or communication data).
[0022] The at least one optical fiber 102 extends longitudinally along a
length of the optical fiber cable 100. In an aspect, the optical fiber cable 100 includes a plurality of optical fibers. The at least one optical fiber 102 is a fiber used for transmitting information as light pulses from one end to another. In addition, the at least one optical fiber 102 is a thin strand of glass or plastic capable of transmitting optical signals. Also, the at least one optical fiber 102 is configured to transmit large amounts of information over long distances with relatively low attenuation. Further, the at least one optical fiber 102 includes a core region and a cladding region. The core region is an inner part of an optical fiber and the cladding section is an outer part of the optical fiber. Moreover, the core region is defined by a central longitudinal axis of each of the at least one optical fiber 102. In addition, the cladding region surrounds the core region.
[0023] The core region and the cladding region are formed along the central
longitudinal axis of the at least one optical fiber 102. Moreover, the core

region and the cladding region are formed during the manufacturing stage of the at least one optical fiber 102. The core region has a refractive index which is greater than a refractive index of the cladding region. In an aspect, the core region has a higher refractive index than the cladding region.
[0024] In an aspect of the present disclosure, the at least one optical fiber
102 has a diameter of 200 ± 20 um. In another aspect, the diameter of the at least one optical fiber 102 may vary. In an aspect, the at least one optical fiber 102 is a single mode fiber. In another aspect, the at least one optical fiber 102 is a multimode fiber. In an aspect, the at least one optical fiber 102 is at least one of loose fibers, flat ribbon, corrugated ribbon and Intermittently Bonded Ribbon. In an aspect, the at least one optical fiber 102 is a ribbon such that adjacent optical fibers in the ribbon are intermittently connected along length.
[0025] The at least one optical fiber 102 is characterized by a macrobend
loss. In general, optical fibers experience additional propagation losses due to bending by coupling light from core modes (guided modes) to cladding modes when they are bent. The macrobend loss occurs when the fibers in a cable are bent are subjected to a significant amount of bending above a critical value of curvature. The at least one optical fiber 102 used in the one or more tubes 104 are insensitive to macrobend losses in order to obtain the optical fiber cable 100 with low optical attenuations. The at least one optical fiber 102 have the macrobend loss of less than or equal to 0.75 dB/turn at 1550 nm when the at least one optical fiber 102 is bent around a mandrel of 10mm radius.
[0026] The optical fiber cable 100 includes the one or more tubes 104. Each
of the one or more tubes 104 encloses the at least one optical fiber 102. In an example, each of the one or more tubes 104 encloses 12 optical fibers. The one or more tubes 104 may enclose any number of optical fibers. In an aspect, the number of the at least one optical fiber 102 in the optical fiber cable 100 is

greater than equal to 72. In another aspect, a number of the at least one optical fiber 102 in the optical fiber cable 100 may vary. In an aspect, each of the one or more tubes 104 surrounds the at least one optical fiber 102. The one or more tubes 104 covers the at least one optical fiber 102. The one or more tubes 104 include one of loose tubes, buffer tubes, tight buffered tubes and the like. Each of the one or more tubes 104 is a tube for encapsulating the at least one optical fiber 102. The one or more tubes 104 provide support and protection to the at least one optical fiber 102 against crush, bend and stretch. In addition, the one or more tubes 104 protect the at least one optical fiber 102 and prevent ingression of water inside.
[0027] Further, the one or more tubes 104 provide mechanical isolation,
physical damage protection and identification of each of the at least one optical fiber 102. In an aspect, the one or more tubes 104 provide a single layer core construction.
[0028] In an aspect, the optical fiber cable 100 includes three tubes (as
shown in FIG. 1). In another aspect, the optical fiber cable 100 includes eight tubes (as shown in FIG. 2). The one or more tubes 104 are stranded around each other. In an aspect, the stranding is S-Z stranding. The one or more tubes 104 are wound around each other in sections with a first direction of winding in an S-shape alternating with the sections with a second direction of winding in a Z-shape. The first direction is a clockwise direction and the second direction is an anticlockwise direction. The SZ stranding of the one or more tubes 104 is performed in order to maintain a uniform lay length, mid-spanning and achieve higher production speeds as compared to helical stranding. In general, the lay length is a longitudinal distance along the length of the optical fiber cable 100 required for the one or more tubes 104 to go all the way around each other. In addition, the S-Z stranding allows uniform

distribution of the stress across the one or more tubes 104. The S-Z stranding may have any number of turns between the S-shape and the Z-shape.
[0029] The one or more tubes 104 are characterized by a tube length and the
optical fiber cable 100 is characterized by a cable length. The at least one optical fiber 102 has a fiber length. In an aspect, the fiber length is 0 to 2% greater than the cable length. The tube length of the one or more tubes 104 is greater than a cable length of the optical fiber cable 100. In an aspect, the tube length is 0 to 2% greater than the cable length. The one or more tubes 104 are characterized by a young's modulus. The young's modulus (E) is a property of the material that tells how easily it can stretch and deform. The young's modulus (E) is defined as a ratio of tensile stress (o) to tensile strain (s), where stress is the amount of force applied per unit area (o = F/A) and strain is extension per unit length (s = dl/1). The one or more tubes 104 has the young's modulus of less than or equal to 700 N.
[0030] The one or more tubes 104 are characterized by a lay length. The one
or more tubes 104 have a lay-length of equal to or more than 400 mm. The one or more tubes 104 have low young's modulus. In addition, the one or more tubes 104 are stranded with high lay length. The stranding of the one or more tubes 104 is done with the high lay length because the one or more tubes 104 is made of a material with low young's modulus. The one or more tubes 104 may get physically damaged if the lay length is kept low. The one or more tubes 104 are characterized by an extra tube length (ETL). The extra tube length and extra fiber length is very low in the optical fiber cable 100 because of the high lay-length. In an aspect, the one or more tubes 104 have the extra tube length (ETL) between 0.02% to 0.2%. The extra tube length
(ETV) = Tube length-Sheath length ^
^ ' Sheath length

[0031] The optical fiber cable 100 may not meet break load requirements if
the young's modulus of the one or more tubes 104 is greater than 700 N. If the lay length of the one or more tubes 104 is less than 400 mm, then the one or more tubes 104 having the low young's modulus may face physical damage and inturn may affect optical fibers. This may induce optical losses in the optical fibers. If the extra tube length (ETL) is below 0.02 %, the optical fibers may experience mechanical stresses and may get damaged during handling of the optical fiber cable 100. If the extra tube length (ETL) is above 0.2 %, the lay length of the one or more tubes 104 has to be kept low which is not desired for the one or more tubes 104 with low young's modulus.
[0032] In an aspect of the present disclosure, the one or more tubes 104 are
made of easy peelable material. In another aspect of the present disclosure, the one or more tubes 104 may be made of any other suitable material. The cross section of the one or more tubes 104 is circular in shape. In an aspect of the present disclosure, the cross section of the one or more tubes 104 may be of any suitable shape. In an aspect of the present disclosure, the one or more tubes 104 have a uniform structure and dimensions. The one or more tubes 104 have a thickness. In an aspect of the present disclosure, the thickness of one or more tubes 104 is equal. In an aspect of the present disclosure, the thickness of one or more tubes 104 is in a range of about 0.1- 0.25 millimeter. In another aspect of the present disclosure, the thickness of the one or more tubes 104 may vary.
[0033] Furthermore, the one or more tubes 104 have an inner diameter and
an outer diameter. In an aspect of the present disclosure, the inner diameter and the outer diameter of the one or more tubes 104 is fixed. In an aspect of the present disclosure, the inner diameter of the one or more tubes 104 is in a range of about 0.9 - 1.35 millimeter. In another aspect of the present disclosure, the inner diameter of the one or more tubes 104 may vary. In an aspect of the present disclosure, the outer diameter of each of the one or more

tubes 104 is in a range of about 1.1 - 1.5 millimeter. In another aspect of the present disclosure, the outer diameter of the one or more tubes 104 may vary.
[0034] The optical fiber cable 100 includes the sheath 106. The sheath 106
encapsulates the one or more tubes 104. In an aspect, the sheath 106 encapsulates one or more layers surrounding the one or more tubes 104 (explained below). In an aspect of the present disclosure, the sheath 106 is made of one of UV (Ultra Violet radiations) proof black medium density polyethylene material and UV proof black high density polyethylene material. In general, medium density polyethylene is a thermoplastic material produced by chromium/silica catalysts, Ziegler-Natta catalysts or metallocene catalysts. In another aspect of the present disclosure, the sheath 106 may be made of any other suitable material. The sheath 106 protects the optical fiber cable 100 from harsh environment and harmful UV rays. In addition, the sheath 106 has the inherent ability to resist crushes, kinks and tensile stress. In an aspect of the present disclosure, the sheath 106 has a thickness in a range of about 1.2 -1.8 millimeter. In another aspect of the present disclosure, the sheath 106 may have any suitable thickness.
[0035] The optical fiber cable 100 includes the one or more strength
members 108. The one or more strength members 108 are at least partially embedded in the sheath 106. In an aspect, the one or more strength members 108 is embedded substantially parallel to a longitudinal axis of the optical fiber cable 100. In another aspect, the one or more strength members 108 may not lie parallel the longitudinal axis. In addition, the one or more strength members 108 provide tensile strength and stiffness to the optical fiber cable 100
[0036] In an aspect, each of the one or more strength members 108 is
stranded metallic wires. In an aspect, the stranded metallic wires are made of steel. In an aspect, the metallic wires are made of brass plated steel wires.

Further, the one or more strength members 108 are characterized by a diameter. In an aspect, the one or more strength members 108 have a diameter in a range of about 0.3 - 0.8 mm. In another aspect, the diameter of the one or more strength members 108 may vary. In an aspect, number of metallic wires in the one or more strength members 108 are 3. In another aspect, the number of metallic wires in the one or more strength members 108 may be more or less than 3. In an aspect of the present disclosure, number of the one or more strength members 108 is two and placed diagonally opposite. In another aspect of the present disclosure, number of the one or more strength members 108 may vary.
[0037] The optical fiber cable 100 includes the one or more layers. In an
aspect, the one or more layers include the first layer 110. However, the one or more layers may include more number of layers. In an aspect, the first layer 110 is made of binder yarns. The binder yarn is used for binding a core of the optical fiber cable 100. In an aspect of the present disclosure, the binder yarn is an aramid yarn. In another aspect of the present disclosure, the binder yarn is made of any other suitable material. The optical fiber cable 100 may include more layers in addition or in place of the first layer 110. The other layers may include a water blocking tape layer, a water swellable yarn layer, fire retardant tape layer, binder tape layer and the like.
[0038] In an aspect, the optical fiber cable 100 includes a water blocking gel
112. The water blocking gel 112 is filled inside the one or more tubes 104. In an aspect of the present disclosure, the water blocking gel 112 is a thixotropic gel. The thixotropic gel prevents ingression of water inside each of the one or more tubes 104 and provides a cushioning to the optical fibers. In an aspect, the one or more tubes 104 may be loose tubes, buffer tubes and tight buffered tubes.

[0039] In an aspect, the optical fiber cable 100 may or may not include a
ripcord. In an aspect, the ripcord is disposed inside the sheath 106. The ripcord may lie substantially along the longitudinal axis of the optical fiber cable 100. The ripcord enables tearing of the sheath 106 to facilitate access to the one or more tubes 104. In an aspect of the present disclosure, the ripcord may be made of a polyester material. In another aspect of the present disclosure, the ripcord may be made of any other suitable material. The ripcord has a circular cross-section.
[0040] The optical fiber cable 100 may have a suitable diameter. In an
aspect of the present disclosure, the diameter of the optical fiber cable 100 is in a range of about 5-8 millimeters.
[0041] The foregoing descriptions of pre-defined aspects of the present
technology have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present technology to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The aspects were chosen and described in order to best explain the principles of the present technology and its practical application, to thereby enable others skilled in the art to best utilize the present technology and various aspects with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present technology.

CLAIMS
We claim:

1. An optical fiber cable (100, 200) comprising:
one or more tubes (104), wherein each of the one or more tubes (104) encloses at least one optical fiber (102), wherein the one or more tubes (104) have a tube length greater than a cable length, wherein the one or more tubes (104) have a young's modulus of less than or equal to 700 N, wherein the one or more tubes (104) have a lay-length of equal to or more than 400 mm;
a sheath (106) surrounding the one or more tubes (104); and
one or more strength members (108) at least partially embedded in the sheath (106), wherein the optical fiber cable (100, 200) breaks at a pre-defined load.
2. The optical fiber cable (100, 200) as claimed in claim 1, wherein the one
or more tubes (104) have an extra tube length (ETL) between 0.02% to 0.2%,
wherein the extra tube length (ETL) = Tube length-sheath length * i QO.
Sheath length
3. The optical fiber cable (100, 200) as claimed in claim 1, wherein the at
least one optical fiber (102) is a ribbon such that adjacent optical fibers in the
ribbon are intermittently connected along length.

4. The optical fiber cable (100, 200) as claimed in claim 1, wherein the tube length is 0 to 2% longer than the cable length.
5. The optical fiber cable (100, 200) as claimed in claim 1, wherein the at least one optical fiber (102) has a macrobend loss of less than or equal to 0.75 dB/turn at 1550 nm when the at least one optical fiber (102) is bent around a mandrel of 10mm radius.
6. The optical fiber cable (100, 200) as claimed in claim 1, wherein the at least one optical fiber (102) has a diameter of 200±20um.
7. The optical fiber cable (100, 200) as claimed in claim 1, further comprising a water blocking gel (112) in the one or more tubes (104).
8. The optical fiber cable (100, 200) as claimed in claim 1, wherein the at least one optical fiber (102) has a fiber length, wherein the fiber length is 0 to 2% greater than the cable length.
9. An optical fiber cable (100, 200) comprising:
one or more tubes (104), wherein each of the one or more tubes (104) encloses at least one optical fiber (102), wherein the at least one optical fiber (102) has a diameter of 200±20um;

a sheath (106) surrounding the one or more tubes (104); and
one or more strength members (108) embedded in the sheath (106), wherein the at least one optical fiber (102) has a macrobend loss of less than or equal to 0.75 dB/turn at 1550 nm when the at least one optical fiber (102) is bent around a mandrel of 10mm radius, wherein the optical fiber cable (100, 200) breaks at a pre-defined load.
10. The optical fiber cable (100, 200) as claimed in claim 9, wherein a number of at least one optical fiber (102) in the optical fiber cable (100, 200) is greater than or equal to 72.
11. The optical fiber cable (100, 200) as claimed in claim 9, wherein each of the one or more strength members (106) is stranded metallic wires.
12. The optical fiber cable (100, 200) as claimed in claim 9, wherein the one or more tubes (104) have a young's modulus of less than or equal to 700N.
13. The optical fiber cable (100, 200) as claimed in claim 9, wherein the one or more tubes (104) have a lay-length of equal to or more than 400 mm.
14. The optical fiber cable (100, 200) as claimed in claim 9, wherein the at least one optical fiber (102) has a fiber length, wherein the fiber length is 0 to 2% greater than a cable length of the optical fiber cable (100, 200).