FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005
COMPLETE SPECIFICATION (SEE SECTION 10 AND RULE 13)
TITLE OF THE INVENTION
"OPTICAL FIBER FOR IN-HOUSE APPLICATIONS"
APPLICANTS:
Name : Sterlite Technologies Limited.
Nationality : Indian
Address : E-l, E-2, E-3 MIDC Waluj,
Aurangabad, Maharashtra - -431136
The following specification describes the invention and the manner in which it is to be performed:-

TECHNICAL FIELD
[0001] The present disclosure relates to a field of fiber optic
transmission. More specifically, the present disclosure relates to an optical fiber for in-house applications.
BACKGROUND
[0002] Over the last few years, there has been a rapid growth in the use
of optical fibers for numerous applications. Presently, these optical fibers are widely utilized in fiber-to-the-home applications. These optical fibers are available for residential and commercial consumers to meet their growing demands for bandwidth and high performance. In order to meet the growing demands of these optical fibers having high performance capabilities, these optical fibers are typically coated with multiple coating layers. These multiple coating layers are a rather significant component that determines physical fiber optic characteristics such as bending, chemical resistance, and mechanical strength. For example, these multiple coating layers protect the optical fibers from mechanical damage and preserve the ability of the optical fibers to transmit signals.
[0003] In one of the prior art with patent number US6768853B2, a
buffered optical fiber is disclosed. The optical fiber includes a core and a cladding. In addition, the optical fiber cable includes a first layer. The first layer is positioned around the optical fiber. The first layer is made of a UV curable acrylate material. Moreover, the optical fiber includes a second layer. The second layer surrounds the first layer. The second layer is made of UV curable acrylate. Further, the optical fiber includes

a third layer. The third layer surrounds the second layer. The third layer is made of UV curable acrylate material having a first modulus for protecting the optical fiber from micro bending forces and enhancing low temperature performance. Furthermore, the optical fiber includes a fourth layer. The fourth layer surrounds the third layer. The fourth layer is an outer buffer layer. The fourth layer is made of a high modulus thermoplastic material. However, the combination of material and limited diameter range does not provide sufficient mechanical and tensile strength to the optical fiber.
[0004] In light of the above stated discussion, there exists a need for an
optical fiber having required strength for in-house applications.
OBJECT OF THE DISCLOSURE
[0005] A primary object of the present disclosure is to provide a tetra-
coated optical fiber for in-house applications.
[0006] Another object of the present disclosure is to provide the tetra-
coated optical fiber having high strength.
[0007] Yet another object of the present disclosure is to provide the
tetra-coated optical fiber which has small diameter.
[0008] Yet another object of the present disclosure is to provide the
tetra-coated optical fiber which has small thickness.

[0009] Yet another object of the present disclosure is to eliminate a
need of cabling the tetra-coated optical fiber.
[0010] Yet another object of the present disclosure is to enable fast
deployment of the tetra-coated optical fiber.
[0011] Yet another object of the present disclosure is to provide the
tetra-coated optical fiber having crush resistant properties suitable for indoor staple installation.
[0012] Yet another object of the present disclosure is to provide the
tetra-coated optical fiber flexible for in-house deployment.
SUMMARY
[0013] In an aspect of the present disclosure, the present disclosure
provides an optical fiber. The optical fiber includes a core region. The core region is defined by a region around a central longitudinal axis of the optical fiber. In addition, the optical fiber includes a cladding region. The cladding region surrounds the core region. Moreover, the optical fiber includes a first coating layer. The first coating layer surrounds the cladding region. Further, the optical fiber includes a second coating layer. The second coating layer surrounds the first coating layer. Furthermore, the optical fiber includes a third coating layer. The third coating layer surrounds the second coating layer. Also, the optical fiber includes a fourth coating layer. The fourth coating layer surrounds the third coating layer. Moreover, the first coating material is made of the UV curable acrylates. In addition, the first

coating layer has a first diameter in a range of 150 µm - 250 urn. Moreover, the first coating layer has a modulus in a range of 0.3 MPa -3 MPa. Also, the second coating layer is made of the UV curable acrylates. In addition, the second coating layer has a second diameter in a range of 250 µm - 350 µm. Further, the second coating layer has a modulus in a range of 0.5 MPa - 1.2 GPa. The third coating layer is made of a UV curable acrylates. The third coating layer has a third diameter in a range of 350 µm - 450 µm. Moreover, the third coating layer has a modulus in a range of 0.5 MPa - 1.2 GPa. The fourth coating layer is made of UV curable acrylates. The fourth coating layer has a fourth diameter in a range of 550 µm - 650 µm. In addition, the fourth coating layer has a modulus of greater than 1.2 GPa. The range of diameter and type of materials used for the first coating layer, the second coating layer, the third coating layer and the fourth coating layer provides strength greater than equal to 5 GPa to the optical fiber.
[0014] In an embodiment of the present disclosure, the optical fiber is
a bend insensitive fiber.
[0015] In an embodiment of the present disclosure, the optical fiber
meets requirements of ITU-T G657 A2.
[0016] In an embodiment of the present disclosure, the optical fiber
meets requirements of ITU-T G657 B3.
[0017] In an embodiment of the present disclosure, the cladding region
has a diameter in a range of 124 µm to 126 µm.

[0018] In an embodiment of the present disclosure, the optical fiber
complies with IEC 60794-2 standard.
[0019] In an embodiment of the present disclosure, the optical fiber
has a cladding non-circularity parameter of less than equal to 1 %.
[0020] In an embodiment of the present disclosure, the optical fiber
has a core concentricity error of less than equal to 0.5 µm.
STATEMENT OF THE DISCLOSURE
[0021] The present disclosure relates to an optical fiber. The optical
fiber includes a core region. The core region is defined by a region around a central longitudinal axis of the optical fiber. In addition, the optical fiber includes a cladding region. The cladding region surrounds the core region. Moreover, the optical fiber includes a first coating layer. The first coating layer surrounds the cladding region. Further, the optical fiber includes a second coating layer. The second coating layer surrounds the first coating layer. Furthermore, the optical fiber includes a third coating layer. The third coating layer surrounds the second coating layer. Also, the optical fiber includes a fourth coating layer. The fourth coating layer surrounds the third coating layer. Moreover, the first coating material is made of the UV curable acrylates. In addition, the first coating layer has a first diameter in a range of 150 µm - 250 µm Moreover, the first coating layer has a modulus in a range of 0.3 MPa - 3 MPa. Also, the second coating layer is made of the UV curable acrylates. In addition, the second coating layer has a

second diameter in a range of 250 µm - 350 µm. Further, the second coating layer has a modulus in a range of 0.5 MPa - 1.2 GPa. The third coating layer is made of a UV curable acrylates. The third coating layer has a third diameter in a range of 350 µm - 450 µm. Moreover, the third coating layer has a modulus in a range of 0.5 MPa - 1.2 GPa. The fourth coating layer is made of UV curable acrylates. The fourth coating layer has a fourth diameter in a range of 550 µm - 650 µm. In addition, the fourth coating layer has a modulus of greater than 1.2 GPa. The range of diameter and type of materials used for the first coating layer, the second coating layer, the third coating layer and the fourth coating layer provides strength greater than equal to 5 GPa to the optical fiber.
BRIEF DESCRIPTION OF THE FIGURES
[0022] Having thus described the disclosure in general terms, reference
will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
[0023] FIG. 1A illustrates a cross-sectional view of an optical fiber, in
accordance with an embodiment of the present disclosure; and
[0024] FIG. IB illustrates a perspective view of the optical fiber of
FIG. 1A, in accordance with an embodiment of the present disclosure.
[0025] It should be noted that the accompanying figures are intended
to present illustrations of exemplary embodiments 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
[0026] In the following description, for purposes of explanation,
numerous specific details are set forth in order to provide a thorough understanding of the present technology. It will be apparent, however, to one skilled in the art that the present technology can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only in order to avoid obscuring the present technology.
[0027] Reference in this specification to "one embodiment" or "an
embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present technology. The appearance of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but no other embodiments.
[0028] 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.
[0029] FIG. 1A illustrates a cross-sectional view of an optical fiber
100, in accordance with an embodiment of the present disclosure. The optical fiber 100 is a fiber used for transmitting information as light pulses from one end to another. The optical fiber 100 is a thin strand of glass or plastic capable of transmitting optical signals. In addition, the optical fiber 100 allows transmission of information in the form of optical signals over long distances. In addition, the optical fiber 100 allows the transmission of information at high bandwidth. In general, a bandwidth is a measure of data-carrying capacity of the optical fiber 100. In an embodiment of the present disclosure, the optical fiber 100 is a small diameter fiber.
[0030] In an embodiment of the present disclosure, the optical fiber
100 is utilized for broadband communication applications. In another embodiment of the present disclosure, the optical fiber 100 may be utilized for other applications. Moreover, the optical fiber 100 complies with specific telecommunication standards. The telecommunication standards are defined by International Telecommunication Union-Telecommunication (hereinafter "ITU-T"). In an embodiment of the

present disclosure, the optical fiber 100 is compliant with G.657 recommendation standard of ITU-T. Furthermore, the ITU-T G.657 recommendation describes geometrical, mechanical and transmission attributes of a single mode bend insensitive optical fiber (shown as the optical fiber 100).
[0031] In an embodiment of the present disclosure, the optical fiber
100 is a bend insensitive optical fiber. The bend insensitive optical fiber is characterized to have low sensitivity to fiber macro-bends and micro-bends. Further, the ITU-T G.657 standard defines a plurality of characteristics associated with the optical fiber 100. The plurality of characteristics includes a mode field diameter, a cladding diameter, a cable cut-off wavelength, a macro bending loss, a dispersion and a refractive index. In addition, the plurality of characteristics includes a core concentricity error, a cladding non-circularity, an attenuation coefficient and the like.
[0032] The cladding non-circularity is defined as a percentage
difference between a maximum radial deviation and minimum radial deviation between a center of core and cladding of the optical fiber 100 normalized to the diameter of the body. In an embodiment of the present disclosure, the optical fiber 100 has the cladding non-circularity parameter of less than equal to 1 %. The core concentricity error is defined as a scalar distance between the center of the core and the center of the cladding in micrometers. In an embodiment of the present disclosure, the optical fiber 100 has a core concentricity error of less than equal to 0.5 urn. Furthermore, the telecommunication standards are

defined by International Electrotechnical Commission (hereinafter "IEC"). In an embodiment of the present disclosure, the optical fiber 100 is compliant with IEC 60794-2 standard.
[0033] Going further, the optical fiber 100 is manufactured by
adopting a plurality of manufacturing techniques. In general, the manufacturing of optical fibers has two major stages. The first stage involves the manufacturing of optical fiber preforms and the second stage involves drawing the optical fibers from the optical fiber preforms. In general, the quality of optical fibers is determined during the manufacturing of the optical fiber preforms. So, a lot of attention is paid towards the manufacturing the optical fiber preforms. These optical fiber preforms include an inner glass core surrounded by a glass cladding having a lower index of refraction. Also, these preforms are manufactured as per the requirements related to a specific refractive index profile, a core diameter, a cladding diameter and the like. The plurality of manufacturing techniques adopted for manufacturing the optical fiber 100 includes but may not be limited to modified chemical vapor deposition, outside vapor deposition, vapor axial deposition, rod-in cylinder (RIC) and the like.
[0034] The optical fiber 100 includes a core region 102 a cladding
region 104, a first coating layer 106, a second coating layer 108, a third coating layer 110 and a fourth coating layer 112. The core region 102 is an inner part of the optical fiber 100. Moreover, the core region 102 and the cladding region 104 are formed during the manufacturing stage of the optical fiber 100. The core region 102 is defined by a region around

a central longitudinal axis 114 of the optical fiber 100. In general, the core region 102 is defined as the region around the central longitudinal axis 114 of the optical fiber 100 through which light transmits. Furthermore, the central longitudinal axis 114 is associated with the optical fiber 100. In general, the central longitudinal axis 114 of the optical fiber 100 passes through a geometrical center of the optical fiber 100 and is parallel to a length of the optical fiber 100 (as shown in FIG. IB). In addition, the central longitudinal axis 114 is mutually perpendicular to a cross-section of the optical fiber 100. The core region 102 is doped with at least one of germanium, fluorine or a combination of both.
[0035] Further, the cladding region 104 of the optical fiber 100
surrounds the core region 102 of the optical fiber 100. In general, the cladding region 104 is defined as a region around the core region 102 which confines a light ray to travel within the core region 102 of the optical fiber 100. In addition, the cladding region 104 confines the light ray in the core region 102 based on total internal reflection at a core-cladding interface. In general, total internal reflection in optical fiber 100 is a phenomenon of complete reflection of the light ray reaching the core-cladding interface. Furthermore, the core region 102 has a refractive index which is greater than a refractive index of the cladding region 104. In an embodiment of the present disclosure, the core region 102 has a higher refractive index than the cladding region 104. In an embodiment of the present disclosure, the cladding region 104 of the optical fiber 100 has a diameter in a range of 124 µm - 126 µm.

[0036] Going further, the optical fiber 100 includes the first coating
layer 106, the second coating layer 108, the third coating layer 110 and the fourth coating layer 112. The first coating layer 106 surrounds the cladding region 104 of the optical fiber 100. In an embodiment of the present disclosure, the first coating layer 106 is an inner coating layer. In an embodiment of the present disclosure, the first coating layer 106 is in direct contact with the cladding region 104. In another embodiment of the present disclosure, one or more adhesive layers are present between the first coating layer 106 and the cladding region 104.
[0037] The first coating layer 106 serves as a cushion and protects the
optical behavior of the optical fiber 100 during bending, cabling and spooling of the optical fiber 100. In addition, the first coating layer 106 protects the core region 102 and preserves the ability of the optical fiber 100 to transmit signals. In an embodiment of the present disclosure, the first coating layer 106 is present between the cladding region 104 and the second coating layer 108. Moreover, the first coating layer 106 has a first diameter. The first diameter lies in the range of 150 µm - 250 µm.
[0038] Further, the first coating layer 106 is formed of a material
having low Young's modulus. The first coating layer 106 has a modulus in a range of 0.3 MPa to 3 MPa. The modulus or Young's modulus is a measure of stiffness of an elastic material. The first coating layer 106 is made of ultraviolet curable acrylates (hereinafter "UV curable acrylates"). Furthermore, the second coating layer 108 surrounds the first coating layer 106. In an embodiment of the present

disclosure, the second coating layer 108 is a first intermediate coating layer. In an embodiment of the present disclosure, the second coating layer 108 is in direct contact with the first coating layer 106. In another embodiment of the present disclosure, the one or more adhesive layers are present between the second coating layer 108 and the first coating layer 106. Also, the second coating layer 108 is made of UV curable acrylates. In addition, the UV curable acrylates provide mechanical strength to the optical fiber 100. UV cured acrylate material have low Young's modulus. Furthermore, the second coating layer 108 has a second diameter. The second diameter lies in the range of 250 urn - 350 |im. The second coating layer 108 has a modulus in a range of 0.5 MPa - 1.2 GPa. In an embodiment of the present disclosure, the value of modulus for the second coating layer 108 is selected based on the modulus value of the first coating layer 106.
[0039] Furthermore, the third coating layer 110 surrounds the second
coating layer 108. In an embodiment of the present disclosure, the third coating layer 110 is a second intermediate coating layer. In an embodiment of the present disclosure, the third coating layer 110 is in direct contact with the second coating layer 108. In another embodiment of the present disclosure, the one or more adhesive layers are present between the third coating layer 110 and the second coating layer 108. The third coating layer 110 is made of ultraviolet curable acrylates. Furthermore, the third coating layer 110 has a third diameter. The third diameter lies in the range of 350 µm - 450µm. In an embodiment of the present disclosure, the third coating layer 110 may be colored. In another embodiment of the present disclosure, the third

coating layer 110 may not be colored. The third coating layer 110 has a modulus in a range of 0.5 MPa - 1.2 GPa. In an embodiment of the present disclosure, the value of modulus for the third coating layer 110 is selected based on the modulus value of the first coating layer 106.
[0040] Furthermore, the fourth coating layer 112 surrounds the third
coating layer 110. In an embodiment of the present disclosure, the fourth coating layer 112 is an outer coating layer. In an embodiment of the present disclosure, the fourth coating layer 112 is in direct contact with the third coating layer 110. In another embodiment of the present disclosure, the one or more adhesive layers are present between the fourth coating layer 112 and the third coating layer 110. The fourth coating layer 112 protects the optical fiber 100 from environmental exposure, mechanical damages, chemical attacks and the like. In addition, the fourth coating layer 112 enables an easy deployment of optical fiber 100. The fourth coating layer 112 is made of ultraviolet curable acrylates. Furthermore, the fourth coating layer 112 has a fourth diameter. The fourth diameter lies in the range of 550 urn - 650 µm. In an embodiment of the present disclosure, the fourth coating layer 112 may be colored. In another embodiment of the present disclosure, the third coating layer 112 may not be colored. The fourth coating layer 112 has a modulus of greater than 1.2 GPa. In an embodiment of the present disclosure, the optical fiber 100 may not include the fourth coating layer 112.
[0041] The combination of the first coating layer 106, the second
coating layer 108, the third coating layer 110 and the fourth coating

layer 112 maintains the optical performance of the optical fiber 100. In addition, the range of diameter and a type of material used for the first coating layer 106, the second coating layer 108, the third coating layer 110 and the fourth coating layer 112 provides strength greater than or equal to 5Giga-Pascal (hereinafter "GPa") to the optical fiber 100. The combination of material and diameter of different layers of the optical fiber 100 provides mechanical and tensile strength to the optical fiber 100. Different material combinations of the first coating layer 106, the second coating layer 108, the third coating layer 110 and the fourth coating layer 112 may be used to maintain the optical performance and strength of the optical fiber 100. Moreover, the optical fiber 100 has four coatings to facilitate direct installation in in-house or harsh environments.
[0042] Furthermore, different diameter combinations associated with
the first coating layer 106, the second coating layer 108, the third coating layer 110 and the fourth coating layer 112 may be used to maintain the strength of the optical fiber 100 to less than 5 GPa. In an embodiment of the present disclosure, the strength of the optical fiber 100 is no less than 5 GPa when the first coating layer 106 has a diameter of 150 urn, the second coating layer 108 has the diameter of 250 µm, the third coating layer 110 has the diameter of 350 µm and the fourth coating layer 112 has the diameter of 550 µm. In another embodiment of the present disclosure, the strength of the optical fiber 100 is no less than 5 GPa when the first coating layer 106 has the diameter of 250 µm, the second coating layer 108 has the diameter of 350 µm, the third coating layer 110 has the diameter of 450 |im and the fourth coating

layer 112 has the diameter of 650µm. In yet another embodiment of the present disclosure, the strength of the optical fiber 100 is no less than 5 GPa when the first coating layer 106 has the diameter of 200 urn, the second coating layer 108 has the diameter of 300 µm, the third coating layer 110 has the diameter of 400 µm and the fourth coating layer 112 has the diameter of 600 urn.
[0043] Going further, the present disclosure provides numerous
advantages over the prior art. The present disclosure provides the optical fiber of strength greater than equal to 5 GPa. The present disclosure provides the optical fiber of reduced size. The optical fiber can be directly deployed for in-house applications without any need of cabling or buffering over the optical fiber and hence reduces cost of manufacturing. Moreover, the optical fiber has crush resistant properties suitable for an indoor staple installation and can withstand harsh environment. The optical fiber is flexible and can be resist effects of chemicals and moisture in contact.
[0044] The foregoing descriptions of specific embodiments 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 embodiments 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 embodiments with various modifications as are

suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as 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.
[0045] While several possible embodiments of the disclosure have
been described above and illustrated in some cases, it should be interpreted and understood as to have been presented only by way of illustration and example, but not by limitation. Thus, the breadth and scope of a preferred embodiment should not be limited by any of the above-described exemplary embodiments.

STATEMENT OF CLAIMS
What is claimed is:
1. An optical fiber comprising:
a core region defined by a region around a central longitudinal axis of the optical fiber;
a cladding region surrounding the core region;
a first coating layer surrounding the cladding region, wherein the first coating layer is made of UV curable acrylates, wherein the first coating layer has a first diameter in a range of 150µm - 250 µm and wherein the first coating layer has a modulus in a range of 0.3 MPa to 3 MPa;
a second coating layer surrounding the first coating layer, wherein the second coating layer is made of UV curable acrylates, wherein the second coating layer has a second diameter in a range of 250 µm - 350µm and wherein the second coating layer has a modulus in a range of 0.5 MPa to 1.2 GPa;
a third coating layer surrounding the second coating layer, wherein the third coating layer is made of UV curable acrylates, wherein the third coating layer has a third diameter in a range of 350 µm - 450

µm and wherein the third coating layer has a modulus in a range of 0.5 MPatol.2GPa;and
a fourth coating layer surrounding the third coating layer, wherein the fourth coating layer is made of UV curable acrylates, wherein the fourth coating layer has a fourth diameter in a range of 550 µm - 650 µm, wherein the fourth coating layer has a modulus of greater than 1.2 GPa, wherein the range of diameter and a type of material used for the first coating layer, the second coating layer, the third coating layer and the fourth coating layer provides strength greater than or equal to 5GPa to the optical fiber.
2. The optical fiber as recited in claim 1, wherein the optical fiber is a bend insensitive fiber.
3. The optical fiber as recited in claim 1, wherein the optical fiber meets requirements of ITU-T G657 A2.
4. The optical fiber as recited in claim 1, wherein the optical fiber meets requirements of ITU-T G657 B3.
5. The optical fiber as recited in claim 1, wherein the optical fiber complies with IEC 60794-2 standard.
6. The optical fiber as recited in claim 1, wherein the cladding region has a diameter in a range of 124 urn - 126 µm.

7. The optical fiber as recited in claim 1, wherein the optical fiber has a cladding non-circularity parameter of less than equal to 1 %.
8. The optical fiber as recited in claim 1, wherein the optical fiber has a core concentricity error of less than equal to 0.5 µm.