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] In recent years, the demand for optical fibers in data
communications and sensing applications has witnessed a sudden rise. This is primarily attributed to ability of optical fibers to provide high bandwidth, robust, low noise network, high throughput, high data rate and mechanical strength to sustain damages and ambient parameters. These optical fibers are widely utilized in fiber-to-the-home applications. Residential and commercial consumers require mechanical and signal performance optimized optical fibers. Typically, these optical fibers are coated with multiple coating layers in order to meet growing demands of mechanical and signal performance optimized optical fibers. These multiple coating layers significantly determine physical characteristics of optical fibers such as macro-bends, chemical abrasion resistance, mechanical strength and the like. These multiple coating layers protect the optical fibers from physical damage and ambient environmental parameters. Further, these multiple coating layers provide flexibility as well as preserve the ability of the optical fibers to transmit signals.
[0003] In one of the prior art with patent application number
US20100043953A1, an optical fiber is disclosed. The optical fiber includes a primary coating for protective purposes. The primary coating

includes a first and a second polymeric coating layer. The polymeric coating layers may be obtained from compositions comprising oligomers and monomers. The oligomers and monomers are generally cross-linked by means of UV irradiation in the presence of a suitable photo-initiator. Typically, the two coating layers are made of UV cured acrylate resin. The two coating layers differ in terms of modulus of elasticity of the cross-linked material. In addition, the first coating layer (i.e., the inner) is typically softer than the second coating layer. The first coating layer has a thickness in a range of about 25 µm to 40 µm. The second coating layer has a thickness in a range of about 20 µm to 40 µm. Accordingly, the diameter of the first coating layer is less than 400 microns. 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 dual-
coated optical fiber for in-house applications.
[0006] Another object of the present disclosure is to provide a dual-
coated optical fiber having high strength and flexibility
[0007] Yet another object of the present disclosure is to provide a
chemical and moisture resistant optical fiber.

[0008] Yet another object of the present disclosure is to provide a dual-coated optical fiber having large diameter.
[0009] Yet another object of the present disclosure is to eliminate a need
of cabling for dual-coated optical fiber.
[0010] Yet another object of the present disclosure is to enable fast
deployment of dual-coated optical fiber.
[0011] Yet another object of the present disclosure is to provide a dual-
coated optical fiber having high strength and crush resistance for indoor staple installation.
SUMMARY
[0012] 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. Further, the optical fiber includes a first coating layer. The first coating layer surrounds the cladding region. Furthermore, the optical fiber includes a second coating layer. The second coating layer surrounds the first 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 400µm - 500 µm. Further, 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 550 µm - 850

|im. Moreover, the second coating layer has a modulus of greater than 1.2 GPa. Furthermore, the range of diameter and type of materials used for the first coating layer and the second coating layer provides strength greater than equal to 5 GPa to the optical fiber.
[0013] In an embodiment of the present disclosure, the optical fiber is a
bend insensitive fiber.
[0014] In an embodiment of the present disclosure, the optical fiber meets
requirements of ITU-T G657 A2.
[0015] In an embodiment of the present disclosure, the optical fiber meets
requirements of ITU-T G657 B3.
[0016] In an embodiment of the present disclosure, the cladding region
has a diameter in a range of 124µm to 126 urn
[0017] In an embodiment of the present disclosure, the optical fiber
complies with IEC 60794-2 standard.
[0018] In an embodiment of the present disclosure, the optical fiber has a
cladding non-circularity parameter of less than equal to 1 %.
[0019] In an embodiment of the present disclosure, the optical fiber has a
core concentricity error of less than equal to 0.5 urn

STATEMENT OF THE DISCLOSURE
[0020] 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. Further, the optical fiber includes a first coating layer. The first coating layer surrounds the cladding region. Furthermore, the optical fiber includes a second coating layer. The second coating layer surrounds the first coating layer. Moreover, the first coating material is made of the U V curable acrylates. In addition, the first coating layer has a first diameter in a range of 400 urn - 500 urn. Further, 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 550 µm - 850 urn. Moreover, the second coating layer has a modulus of greater than 1.2 GPa. Also, the second coating layer is made of UV curable acrylates. In addition, the second coating layer has a second diameter in a range of 550 urn - 850 urn. Furthermore, the range of diameter and type of material used for the first coating layer and the second coating layer provides strength greater than equal to 5 GPa to the optical fiber.
BRIEF DESCRIPTION OF THE FIGURES
[0021] 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:

[0022] FIG. 1A illustrates a cross-sectional view of an optical fiber, in
accordance with an embodiment of the present disclosure; and
[0023] FIG. IB illustrates a perspective view of the optical fiber of FIG. 1A, in accordance with an embodiment of the present disclosure.
[0024] 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
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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 high diameter fiber.

[0029] 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).
[0030] 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.
[0031] 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.
[0032] 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.

[0033] The optical fiber 100 includes a core region 102 a cladding region
104, a first coating layer 106 and a second coating layer 108. 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 110 of the optical fiber 100. In general, the core region 102 is defined as the region around the central longitudinal axis 110 of the optical fiber 100 through which light transmits. Furthermore, the central longitudinal axis 110 is associated with the optical fiber 100. In general, the central longitudinal axis 110 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 110 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.
[0034] 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 (A) in a range of 124 \im - 126 um.
[0035] Going further, the optical fiber 100 includes the first coating layer
106 and the second coating layer 108. 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.
[0036] 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 (B). The first diameter (B) lies in the range of 400 urn - 500 [im.
[0037] 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 an outer 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. The second coating layer 108 protects the optical fiber 100 from environmental exposure, mechanical damages, chemical attacks and the like. In addition, the second coating layer 108 enables an easy deployment of optical fiber 100. 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 material has a second diameter (C). The second diameter (C) lies in the range of 550 um - 850 urn The second coating layer 108 has a modulus of greater than 1.2 GPa.
[0038] The combination of the first coating layer 106 and the second
coating layer 108 maintains the optical performance of the optical fiber 100. In addition, the combination of the first diameter (B) and the material of the first coating layer 106 and the second diameter (C) and the material of the second coating layer 108 provides strength greater than or equal to 5 Giga-Pascal (hereinafter "GPa"). The combination of material and diameter of different layers of the optical fiber provides mechanical and tensile strength to the optical fiber. Different material combinations of the

first coating layer 106 and the second coating layer 108 may be used to maintain the optical performance and strength of the optical fiber 100. Moreover, the optical fiber 100 has dual coatings to facilitate direct installation in in-house or harsh environments.
[0039] Furthermore, different diameter combinations associated with the
first coating layer 106 and the second coating layer 108 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 400 |jm and the second coating layer 108 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 500 µm and the second coating layer 108 has the diameter of 850 urn. 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 450 µm and the second coating layer 108 has the diameter of 700 urn
[0040] 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.
[0041] 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.
[0042] 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.

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 µm - 126 urn
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.