Air blown optical fiber cable

Abstract

Disclosed is an air blown optical fiber cable (100, 200) comprising one or more optical fiber ribbons (102) and a sheath (104) that surrounds the one or more optical fiber ribbons (102). The sheath (104) is a single layer of thermoplastic material. Further, the air blown optical fiber cable (100, 200) is free from any strength members.

Description

“AIR BLOWN OPTICAL FIBER CABLE”The following specification particularly describes the invention and the manner in which it is to be performed: -TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the field of optical telecommunication systems, and more particularly, relate to an air blown optical fiber cable.

[0002] This application claims the benefit of Indian Application No. “202311079206” titled “AIR BLOWN OPTICAL FIBER CABLE” filed by the applicant on 22ndNovember, 2023, which is incorporated herein by reference in its entirety.Background Art

[0003] Modem optical devices and optical communications systems widely use fiber optic cables. Fiber optic cables are often used to transmit light signals for high speed data transmission. A fiber optic cable typically includes an optical fiber or optical fibers, a buffer or buffers that surround the fiber or fibers, a strength layer that surrounds the buffer or buffers, and an outer jacket. The optical fibers function to carry optical signals.

[0004] Optical fiber refers to the technology and the medium for the transmission of data as light pulses along an ultrapure strand of glass, which is as thin as a human hair. For many years, optical fibers have been extensively used in high-performance and long-distance data and networking.

[0005] An optical fiber cable generally has one or more optical fibers and a sheath surrounding the one or more optical fibers. Traditionally, a compact optical fiber cable having a diameter in a range of less than 5 millimetres (mm) is made with thin sheath. Therefore, it is not feasible to embed strength members inside such thin sheaths. Moreover, increasing a thickness of the sheath will increase the diameter and the weight of the optical fiber cable, which is not desirable. Further, a central strength member can also not be used because of space constraint inside the optical fiber cable.

[0006] Prior art reference “US10444460B2” discloses an optical fiber cable with optical fibers and strength yams in the core.

[0007] Another prior art reference “EP1982222B1” discloses a dual layer sheath cable.

[0008] Yet another prior art reference “US9482838B2” discloses a tensile yam layer between optical fibers and sheath. However, none of the prior art references discloses a compact size optical fiber cable that meets the air blowing requirements for the optical fiber cable.

[0009] Therefore, there is a need for an optical fiber cable that overcomes one or more limitations associated with the available optical fiber cables.

[0010] Thus, the present disclosure proposes a technical solution that overcomes the above-stated limitations in the prior arts by providing an air blown optical fiber cable.SUMMARY OF THE DISCLOSURE

[0011] Embodiments of the present disclosure relates to an air blown optical fiber cable comprising one or more optical fiber ribbons and a sheath that surrounds the one or more optical fiber ribbons. In particular, the sheath is a single layer of thermoplastic material. Further, the air blown optical fiber cable is free from any strength members.

[0012] According to the first aspect of the present disclosure, the air blown optical fiber cable further comprising one or more water swellable yarns (WSYs) helically wrapped around the one or more optical fiber ribbons. The one or more WSYs is coated with a Superabsorbent polymer (SAP), where the SAP has a particle size of less than 150 micrometres (pm). Further, the one or more WSYs are wrapped at a lay length that is in a range of 200 millimetres (mm) to 600 mm.

[0013] According to the second aspect of the present disclosure, the air blown optical fiber cable is free from any additional water blocking components.

[0014] According to the third aspect of the present disclosure, the one or more optical fiber ribbons has 1 to 4 optical fiber ribbons.

[0015] According to the fourth aspect of the present disclosure, the outer diameter (OD) of the air blown optical fiber cable is less than 5 millimetres (mm).

[0016] According to the fifth aspect of the present disclosure, the sheath is made up of a material having a young’s modulus of greater than 1800 Mega Pascals (MPa). In particular, the sheath has a thickness in a range of 0.5 mm to 0.6 mm.

[0017] According to the sixth aspect of the present disclosure, the air blown optical fiber cable (100, 200) is air blown to a distance of 1000 meters (m) at an average speed of at least 40 meters / minute (m / min) with a duct filling ratio that is in a range of 65% to 75% at a maximum air pressure of 14±lbar.

[0018] According to the sixth aspect of the present disclosure, a filling coefficient of the air blown optical fiber cable is greater than 35%.

[0019] According to the seventh aspect of the present disclosure, a crush resistance of the air blown optical fiber cable (100, 200) is in the range of 500 Newton (N) / 100 millimetres (mm) to 800 N / 100 mm.

[0020] According to the eighth aspect of the present disclosure, the one or more ribbons is an intermittently bonded ribbon.

[0021] Another embodiment of the present disclosure, the air blown optical fiber cable comprising one or more optical fiber ribbons ; and a sheath that surrounds the one or more optical fiber ribbons. The air blown optical fiber cable does not have strength members embedded in the sheath. Moreover, the sheath is made of a material having a young’s modulus of greater than 1800 Mega Pascals (MPa). Further, the sheath has a thickness in a range of 0.2 mm to 0.8 mm, where the air blown optical fiber cable is configured to air blown to a distance of 1000 meters (m) with a duct filling ratio that is in a range of 65% to 75% at a maximum air pressure between 10 - 15 bar.

[0022] The foregoing objectives of the present disclosure are attained by providing an optical fiber cable.BRIEF DESCRIPTION OF DRAWINGS

[0023] To describe the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the following briefly describes the accompanying drawings required for describing the embodiments or the prior art. Apparently, the accompanying drawings in the following description merely show some embodiments of the present disclosure, and a person of ordinary skill in the art can derive other implementations from these accompanying drawings without creative efforts. All of the embodiments or the implementations shall fall within the protection scope of the present disclosure.

[0024] Fig. 1 A is a pictorial snapshot illustrating a cross-sectional view of an air blown optical fiber cable in accordance with an embodiment of the present disclosure;

[0025] Fig. IB is a pictorial snapshot illustrating an isometric view of the air blown optical fiber cable in accordance with an embodiment of the present disclosure;

[0026] Fig. 2 is a pictorial snapshot illustrating an isometric view of an optical fiber cable in accordance with an embodiment of the present disclosure.

[0027] The air blown optical fiber cable illustrated in the accompanying drawings, which like reference letters indicate corresponding parts in the various figures. It should be noted that the accompanying figure is intended to present illustrations of exemplary embodiments of the present disclosure. This figure is not intended to limit the scope of the present disclosure. It should also be noted that the accompanying figure is not necessarily drawn to scale.DESCRIPTION OF EMBODIMENTS

[0028] Those skilled in the art will be aware that the present disclosure is subject to variations and modifications other than those specifically described. It is to be understood that the present disclosure includes all such variations and modifications. The disclosure also includes all such steps, features, compositions and compounds referred to or indicated in this specification, individually or collectively, and any and all combinations of any or more of such steps or features. Definitions:

[0029] For convenience, before further description of the present disclosure, certain terms employed in the specification, and examples are collected here. These definitions should be read in the light of the remainder of the disclosure and understood as by a person of skill in the art. The terms used herein have the meanings recognized and known to those of skill in the art, however, for convenience and completeness, particular terms and their meanings are set forth below.

[0030] The articles "a", "an" and "the" are used to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article.

[0031] The terms "comprise" and "comprising" are used in the inclusive, open sense, meaning that additional elements may be included. It is not intended to be construed as "consists of only". Throughout this specification, unless the context requires otherwise the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated element or step or group of element or steps but not the exclusion of any other element or step or group of element or steps.

[0032] The following brief definition of terms shall apply throughout the present disclosure:

[0033] The term “optical fiber” as used herein refers to a light guide that provides highspeed data transmission. The optical fiber has one or more glass core regions and one or more glass cladding regions. The light moving through the glass core regions of the optical fiber relies upon the principle of total internal reflection, where the glass core regions have a higher refractive index (nl) than the refractive index (n2) of the glass cladding region of the optical fiber.

[0034] The term “optical fiber cable” as used herein refers to a cable that encloses a plurality of optical fibers.

[0035] The term “glass core region” as used herein refers to an inner most cylindrical structure present in the optical fiber which is configured to guide the light rays inside the optical fiber.

[0036] The term “cladding region” as used herein refers to one or more layered structure covering the core of an optical fiber from the outside, which is configured to possess a lower refractive index than the refractive index of the core to facilitate total internal reflection of light rays inside the optical fiber. Further, the cladding of the optical fiber may include an inner cladding layer coupled to the outer surface of the core of the optical fiber and an outer cladding layer coupled to the inner cladding from the outside.

[0037] The term “duct filling ratio” as used herein refers to cross-sectional area of an optical fiber cable with respect to its outer diameter / a cross-sectional area of a duct with respect to its inner diameter.

[0038] The term “air blown” as used herein refers to an installation by using high speed air flow combined with additional mechanical pushing force known as “blowing or jetting”. Cable blowing is a process of installation of optical fiber cable into a pre-installed duct. Compressed air is injected in the duct inlet after few hundred meters of cable is pushed into the duct. Compressed air flows at high speed through the duct and along the cable.

[0039] The term “filling coefficient” as used herein refers to a ratio of sum of cross- sectional area of all the optical fibers to the cross-sectional area enclosed by an outer surface of the sheath of an optical fiber cable.

[0040] The term “crush resistance” as used herein refers to an ability of an optical fiber cable to withstand external pressure without experiencing significant deformation, signal loss, or damage.

[0041] The term “intermittently bonded ribbon” as used herein refers to a type of optical fiber ribbon made up of a plurality of optical fibers that are bonded together at specific regions along a length to form a ribbon-like structure. The plurality of optical fibers is placed in parallel and adjacent optical fibers are bonded with special material intermittently along a longitudinal length.

[0042] Fig. 1 A is a pictorial snapshot illustrating a cross-sectional view of an air blown optical fiber cable in accordance with an embodiment of the present disclosure. The optical fiber cable 100 (hereinafter interchangeably referred to and designated as “the optical fiber cable 100”) may have one or more optical fibers ribbons 102 of which first and second optical fiber ribbons 102a and 102b are shown. Further, the optical fiber cable 100 may have a sheath 104. The air blown optical fiber cable 100 may be free from any strength members.

[0043] In other words, the air blown optical fiber cable 100 may be free from any strength members embedded in the sheath 100 and any strength members inside the sheath 104 of the air blown optical fiber cable 100. Furthermore, the air blown optical fiber cable 100 may be free from any reinforced rods, metal rods, tensile yams, and the like.

[0044] In accordance with an embodiment of the present disclosure, the one or more optical fiber ribbons 102 (z.e., the first and second optical fiber ribbons 102a and 102b) may be disposed parallel to one another along a length of the optical fiber cable 100. In particular, the one or more optical fiber ribbons 102 may be a rollable ribbon. Moreover, the one or more optical fiber ribbons 102 may be an intermittently bonded ribbon (IBR). Aspects of the present disclosure are intended to include and / or otherwise cover any type of the one or more optical fiber ribbons 102, without deviating from the scope of the present disclosure.

[0045] In accordance with an embodiment of the present disclosure, the one or more optical fiber ribbons 102 may be substantially similar to one another. Each optical fiber ribbon of the one or more optical fiber ribbons 102 may have one or more optical fibers (not shown) such that each optical fiber of the one or more optical fiber ribbons 102 (z.e., the first and second optical fiber ribbons 102a and 102b) may have a core (not shown), a cladding (not shown), one or more outer coating layers (not shown). Further, the one or more optical fiber ribbons 102 (z.e., the first and second optical fiber ribbons 102a and 102b) may be adapted to facilitate transmission of data in the form of optical signals.

[0046] Although FIG. 1 A illustrates that the one or more optical fiber ribbons 102 has 2 optical fiber ribbons (z.e., the first and second optical fiber ribbons 102a and 102b), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects of the present disclosure, the one or more optical fiber ribbons 102 may have 1 to 4 optical fiber ribbons, without deviating from the scope of the present disclosure.

[0047] The sheath 104 may be an outermost layer of the optical fiber cable 100 that may provide support, strength, and insulation to the optical fiber cable 100. In particular, the sheath 104 may facilitate to reduce abrasion and to provide the optical fiber cable 100 with extra protection against external mechanical effects such as crushing. Moreover, the sheath 104 may be a single layer made up of a thermoplastic material that may be made up of a material having a young’s modulus of greater than 1800 Mega Pascals (MPa). When the young’s modulus is below 1800 MPa, the sheath 104 may not have enough mechanical strength to withstand the blowing process and crush resistance of greater than 800 N / 100 mm, therefore, the young’s modulus of the sheath 104 is kept greater than 1800 MPa. Further, the material may be, but not limited to, Polyethylene (PE) material, Polyvinyl Chloride (PVC) material, polyamide (PA) material, and the like. Aspects of the present disclosure are intended to include and / or otherwise cover any type of the thermoplastic material for the sheath 104, known to a person having ordinary skill in the art, without deviating from the scope of the present disclosure.

[0048] In some aspects of the present disclosure, the sheath 104 may have a thickness in a range of 0.5 mm to 0.6 mm. When the thickness of the sheath 104 is below 0.5 mm, the sheath 104 may not have sufficient mechanical strength to withstand blowing and low crush resistance. Similarly, when the thickness of the sheath 104 is above 0.6 mm, the diameter of the optical fiber cable 100 and the weight of the optical fiber cable 100 may increase, which also affects the blowing performance. Therefore, the thickness of the sheath 104 is kept in the range of 0.5 mm to 0.6 mm. In some aspects of the present disclosure, the air blown optical fiber cable 100 may be free from any additional thermoplastic layer.

[0049] The optical fiber cable 100 may further have one or more water swellable yarns (WSYs) 106 of which first and second WSYs 106a and 106b are shown. The one or more WSYs 106 may be wrapped around the one or more optical fiber ribbons 102. Particularly, a number of the WSYs 106 may depend on a number of the one or more optical fiber ribbons 102. For example, each optical fiber ribbon of the one or more optical fiber ribbons 102 may be wrapped by at least one WSYs of the one or more WSYs 106.

[0050] In accordance with an embodiment of the present disclosure, one or more optical fiber ribbons 102 may be wrapped together by the one or more WSYs 106. In particular, the one or more WSYs 106 may be coated with a Superabsorbent polymer (SAP). In other words, each of the first through second WSYs 106a- 106b may be coated with the SAP such that the SAP has a particle size of less than 150 micrometres (pm). When the particle size of the SAP is above 150 pm, more stresses may be exerted on the optical fibers which can cause optical attenuation. Moreover, more space may be occupied inside the optical fiber cable 100. Therefore, the particle size of the SAP is kept less than 150 pm. The air blown optical fiber cable 100 may be free from any additional water blocking components such as water blocking tape.

[0051] In accordance with an embodiment of the present disclosure, the optical fiber cable 100 may have an outer diameter (OD) that may be less than 5 millimetres (mm). In some other aspects of the present disclosure, the outer diameter (OD) of the optical fiber cable 100 may be less than or equal to 3.5 mm.

[0052] In accordance with an embodiment of the present disclosure, the optical fiber cable may be air blown to a distance of 1000 meters (m) (as per IEC (International Electrotechnical Commission) standard) at an average speed of at least 40 meters / minute (m / min) with a duct filling ratio that may be in a range of 65% to 75% at a maximum air pressure of 14±lbar. In particular, the optical fiber cable 100 may have a filling coefficient of greater than 35%. When the filling coefficient is below 35%, a size of the optical fiber cable 100 may increase, that wouldin turn increase the weight and impact of the blowing performance. Therefore, the filling coefficient is kept greater than 35%.

[0053] In accordance with an embodiment of the present disclosure, the optical fiber cable 100 may have a crush resistance in a range of 500 Newton (N) / 100 millimetres (mm) to 800 N / 100 mm. When the crush resistance is below 500, the optical fiber cable 100 may not be able to withstand air pressure during the blowing process. On the other hand, when the crush resistance is above 800, the optical fiber cable 100 may become too stiff and handling the optical fiber cable 100 may be troublesome. Therefore, the crush resistance is kept in the range of 500 N / 100 mm to 800 N / 100 mm. In some aspects of the present disclosure, the optical fiber cable 100 may have a weight that may be less than 5±1 Kilogram / Kilometre (Kg / km).

[0054] Fig. IB is a pictorial snapshot illustrating an isometric view of the air blown optical fiber cable in accordance with an embodiment of the present disclosure. The optical fiber cable 100 may have the one or more water swellable yarns (WSYs) 106 of which the first and second WSYs 106a and 106b are shown. In particular, the one or more WSYs 106 may be helically wrapped around the one or more optical fiber ribbons 102. Moreover, the first and second WSYs 106a and 106b may be helically wrapped around the first and second optical fiber ribbons 102a and 102b, respectively. Further, the one or more WSYs 106 may be wrapped around the one or more optical fiber ribbons 102 at a lay length (L) that may be in a range of 200 millimetres (mm) to 600 mm. Furthermore, the first WSY 106a may be wrapped around the first optical fiber ribbon 102a at the lay length (L) that may be in the range of 200 millimetres (mm) to 600 mm.

[0055] Similarly, the second WSY 106b may be wrapped around the second optical fiber ribbon 102b at the lay length (L) that may be in the range of 200 millimetres (mm) to 600 mm. When the lay length (L) is below 200 mm, a large area of the WSYs 106 may come in contact with the optical fibers of the one or more optical fiber ribbons 102, that may induce stresses and micro bending attenuations. Moreover, the lay length (L) below 200 mm may reduce manufacturing speed of a core of the optical fiber cable 100. On the other hand, when the laylength (L) is above 600 mm, a length of the WSYs 106 will not be sufficient to block water ingression inside the optical fiber cable 100. Therefore, the lay length (L) of the WSYs 106 is kept in the range of 200 mm to 600 mm.

[0056] Fig. 2 is a pictorial snapshot illustrating an isometric view of an optical fiber cable in accordance with an embodiment of the present disclosure. The optical fiber cable 200 may be substantially similar to the optical fiber cable 100 with elements referenced with reference numerals. However, the one or more WSYs 106 of the optical fiber cable 200 has a single WSY (hereinafter referred to and designated as “the WSY 106”). The WSY 106 may be helically wrapped around the one or more optical fiber ribbons 102. Particularly, the WSY 106 may be helically wrapped around the first and second optical fiber ribbons 102a and 102b. Moreover, the WSY 106 may be wrapped around the one or more optical fiber ribbons 102 at the lay length (L) that may be in a range of 200 millimetres (mm) to 600 mm. When the lay length (L) is below 200 mm, a large area of the WSY 106 may come in contact with the optical fibers of the one or more optical fiber ribbons 102, that may induce stresses and micro bending attenuations. Further, the lay length (L) below 200 mm may reduce manufacturing speed of a core of the optical fiber cable 100. On the other hand, when the lay length (L) is above 600 mm, a length of the WSY 106 will not be sufficient to block water ingression inside the optical fiber cable 100. Therefore, the lay length (L) of the WSY 106 is kept in the range of 200 mm to 600 mm.

[0057] Thus, the optical fiber cable 100, 200 of the present disclosure is a reduced diameter optical fiber cable and has reduced weight due to the absence of any strength members and any additional water blocking components. The optical fiber cable 100, 200 of the present disclosure has a single layer sheath made up of a thermoplastic material (i.e., the sheath 104) having optimized parameters and properties facilitating the optical fiber cable 100, 200 to provide better blowing performance and having compact size, having no strength members and meeting the air blowing requirements of the cable. Further, the optical fiber cable 100, 200has optimizedproperties and parameters of the sheath 104 of the optical fiber cable 100, 200 to enable the above requirements without the need of strength members.

[0058] 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 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.

[0059] In a case that no conflict occurs, the embodiments in the present disclosure and the features in the embodiments may be mutually combined. The foregoing descriptions are merely specific implementations of the present disclosure, but are not intended to limit the protection scope of the present disclosure. Any variation or replacement readily figured out by a person skilled in the art within the technical scope disclosed in the present disclosure shall fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

We claim1. An air blown optical fiber cable (100, 200) characterized in that: one or more optical fiber ribbons (102); and a sheath (104) that surrounds the one or more optical fiber ribbons (102), wherein the sheath (104) is a single layer of thermoplastic material; wherein the air blown optical fiber cable (100) is free from any strength members.

2. The air blown optical fiber cable (100, 200) of claim 1, further comprising one or more water swellable yams (WSYs) (106) helically wrapped around the one or more optical fiber ribbons (102).

3. The air blown optical fiber cable (100, 200) of claim 2, wherein the one or more WSYs (106) is coated with a Superabsorbent polymer (SAP), wherein the SAP has a particle size of less than 150 micrometres (pm).

4. The air blown optical fiber cable (100, 200) of claim 2, wherein the air blown optical fiber cable (100) is free from any additional water blocking components.

5. The air blown optical fiber cable (100, 200) of claim 1, wherein the one or more optical fiber ribbons (102) has 1 to 4 optical fiber ribbons.

6. The air blown optical fiber cable (100, 200) of claim 1, wherein an outer diameter (OD) of the air blown optical fiber cable (100, 200) is less than 5 millimetres (mm).

7. The air blown optical fiber cable (100, 200) of claim 1, wherein the sheath (104) is made up of a material having a young’s modulus of greater than 1800 Mega Pascals (MPa).

8. The air blown optical fiber cable (100, 200) of claim 1, wherein the sheath (104) has a thickness in a range of 0.5 mm to 0.6 mm.

9. The air blown optical fiber cable (100, 200) of claim 1, wherein the air blown optical fiber cable (100, 200) is air blown to a distance of 1000 meters (m) at an average speed of at least 40 meters / minute (m / min) with a duct filling ratio that is in a range of 65% to 75% at a maximum air pressure of 14±lbar.

10. The air blown optical fiber cable (100, 200) of claim 1, wherein the one or more WSYs (106) are wrapped at a lay length that is in a range of 200 millimetres (mm) to 600 mm.

11. The air blown optical fiber cable (100, 200) of claim 1, wherein a filling coefficient of the air blown optical fiber cable (100) is greater than 35%.

12. The air blown optical fiber cable (100, 200) of claim 1, wherein a crush resistance of the air blown optical fiber cable (100, 200) is in arrange of 500 Newton (N) / 100 millimetres (mm) to 800 N / 100 mm.

13. The air blown optical fiber cable (100, 200) of claim 1, wherein the one or more ribbons (102) is an intermittently bonded ribbon.

14. An air blown optical fiber cable (100, 200) characterized in that: one or more optical fiber ribbons (102); and a sheath (104) that surrounds the one or more optical fiber ribbons (102), wherein the air blown optical fiber cable (100) does not have strength members embedded in the sheath (104), wherein the sheath (104) is made of a material having a young’s modulus of greater than 1800 Mega Pascals (MPa), wherein the sheath (104) has a thickness in a range of 0.2 mm to 0.8 mm, wherein the air blown optical fiber cable (100, 200) is configured to air blown to a distance of 1000 meters (m) with a duct filling ratio that is in a range of 65% to 75% at a maximum air pressure between 10 - 15 bar.

15. The air blown optical fiber cable (100, 200) of claim 14, wherein a filling coefficient of the air blown optical fiber cable (100) is greater than 35% and an outer diameter (OD) of the air blown optical fiber cable (100, 200) is less than 5 millimetres (mm).

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