Description:TECHNICAL FIELD
The present disclosure relates to the field of optical fiber cables and, in particular, relates to an air blown optical fiber cable.
BACKGROUND
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. 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.
A prior art reference “US10444460B2” discloses an optical fiber cable with optical fibers and strength yarns in the core. Another prior art reference “EP1982222B1” discloses a dual layer sheath cable. Yet another prior art reference “US9482838B2” discloses a tensile yarn layer between optical fibers and sheath. However, none of the prior art reference discloses a compact size optical fiber cable that meets the air blowing requirements for the optical fiber cable.
Therefore, there is a need for an optical fiber cable that overcomes one or more limitation associated with the available optical fiber cables.
SUMMARY
In an aspect of the present disclosure, an air blown optical fiber cable is disclosed. The air blown optical fiber cable has one or more optical fiber ribbons and a sheath that surrounds the one or more optical fiber ribbons. The sheath is a single layer of thermoplastic material. Further, the air blown optical fiber cable is free from any strength members.
BRIEF DESCRIPTION OF DRAWINGS
Having thus described the disclosure in general terms, reference will now be made to the accompanying figures, where:
FIG. 1A illustrates a cross-sectional view of an air blown optical fiber cable.
FIG. 1B illustrates an isometric view of the air blown optical fiber cable of FIG. 1A.
FIG. 2 illustrates an isometric view of an optical fiber cable.
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.
DEFINITIONS
The term “optical fiber” as used herein refers to a light guide that provides high-speed 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 (n1) than the refractive index (n2) of the glass cladding region of the optical fiber.
The term “optical fiber cable” as used herein refers to a cable that encloses a plurality of optical fibers.
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.
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.
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.
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.
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.
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.
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.
DETAILED DESCRIPTION
The detailed description of the appended drawings is intended as a description of the currently preferred aspects of the present disclosure, and is not intended to represent the only form in which the present disclosure may be practiced. It is to be understood that the same or equivalent functions may be accomplished by different aspects that are intended to be encompassed within the spirit and scope of the present disclosure.
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.
FIG. 1A illustrates a cross-sectional view of an air blown optical fiber cable 100. 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. The optical fiber cable 100 may further have a sheath 104. The air blown optical fiber cable 100 may be free from any strength members. 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. Further, the air blown optical fiber cable 100 may be free from any reinforced rods, metal rods, tensile yarns, and the like.
The one or more optical fiber ribbons 102 (i.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 some aspects of the present disclosure, the one or more optical fiber ribbons 102 may be a rollable ribbon. In some other aspects of the present disclosure, 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. In some aspects 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 (i.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). The one or more optical fiber ribbons 102 (i.e., the first and second optical fiber ribbons 102a and 102b) may be adapted to facilitate in transmission of data in the form of optical signals. Although FIG. 1A illustrates that the one or more optical fiber ribbons 102 has 2 optical fiber ribbons (i.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.
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. Further, 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. Specifically, 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 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. In some aspects of the present disclosure, 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. 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.
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. Specifically, 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. In some aspects of the present disclosure, one or more optical fiber ribbons 102 may be wrapped together by the one or more WSYs 106. In some aspects of the present disclosure, 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 (µm). When the particle size of the SAP is above 150 µm, 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 µm. The air blown optical fiber cable 100 may be free from any additional water blocking components such as water blocking tape.
In some aspects 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.
In some aspects 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±1bar. In some aspects of the present disclosure, 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 would in turn increase the weight and impact of the blowing performance. Therefore, the filling coefficient is kept greater than 35%.
In some aspects 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 blowing process. On the other hand, when the crush resistance is above 800, the optical fiber cable 100 may become too stiff and handing 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).
FIG. 1B illustrates an isometric view of the optical fiber cable 100 of FIG. 1A. As discussed, 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. The one or more WSYs 106 may be helically wrapped around the one or more optical fiber ribbons 102. Specifically, the first and second WSYs 106a and 106b may be helically wrapped around the first and second optical fiber ribbons 102a and 102b, respectively. In some aspects of the present disclosure, 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. Specifically, 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. 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 lay length (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.
FIG. 2 illustrates an isometric view of an optical fiber cable 200. The optical fiber cable 200 may be substantially similar to the optical fiber cable 100 with like elements referenced with like 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. Specifically, the WSY 106 may be helically wrapped around the first and second optical fiber ribbons 102a and 102b. In some aspects of the present disclosure, 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. 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 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.
Thus, the optical fiber cable 100, 200 of the present disclosure is a reduced diameter optical fiber cable. Further, the optical fiber cable 100, 200 of the present disclosure 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 that facilitates the optical fiber cable 100, 200 to provide better blowing performance and having compact size, having no strength members and meeting the airblowing requirements of the cable. The optical fiber cable 100, 200has optimized properties and parameters of the sheath 104 of the optical fiber cable 100, 200to enable the above requirements without the need of strength members.
The foregoing descriptions of specific aspects of the present technology have been presented for the purpose 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.
While several possible aspects of the invention 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 aspect should not be limited by any of the above-described exemplary aspects. , Claims:I/We Claim(s):
1. An air blown optical fiber cable (100, 200) comprising:
one or more optical fiber ribbons (102);
a sheath (104) that surrounds the one or more optical fiber ribbons (102), where the sheath (104) is a single layer of thermoplastic material;
where 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 yarns (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), where the SAP has a particle size of less than 150 micrometres (µm).

4. The air blown optical fiber cable (100, 200) of claim 2, where 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, where 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, where 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, where 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, where 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, where 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±1bar.

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