Description:TECHNICAL FIELD
The present disclosure relates generally to an optical fiber manufacturing apparatus, and, more particularly, to an apparatus and a method for manufacturing an optical fiber using non-contact pneumatic levitation.
BACKGROUND
Optical fibers are used to transmit large size of information modulated on an optical signal to longer distances at higher data rates without being hampered by electromagnetic interference. The compact size of optical fibers results in reduced occupancy area by a bundle of optical fibers, however due to the compact size of optical fibers it is very difficult to draw, support and handle optical fibers. Conventionally, multiple forms of optical tweezers have been used to support, draw and handle compact sized structures such as optical fibers. Further, the optical signal faces Rayleigh scattering, that is responsible for attenuation in the optical signal. Rayleigh scattering is higher in the optical systems without proper cooling mechanism for the bare optical fibers.

In reference to the above-mentioned challenges, a prior art US9650283B2 discloses a method for turning of the fibre using different Reynolds numbers by varying the inlet gas velocities at 3 different positions in 90 degrees. Prior arts US8074474B2 and WO2019036260 disclose turning mechanism of the optical fiber using convex force. The prior arts US9650283B2, US8074474B2 and WO2019036260 disclose creation of the pressure difference on two sides of the fiber and further disclose air as coolant for the bare fibers.

In Prior art US9650283B2, due to the use of different Reynolds numbers that are obtained by varying the inlet gas velocities at 3 different positions in 90 degrees, the system of Prior art US9650283B2 suffers higher computational complexity as variables of Reynolds numbers have exponential dependencies.
Due to convex force-controlled creation of pressure, the system of prior arts US9650283B2 and US8074474B2 use convex force involving polynomial relationship between the variables, thus suffer higher computational complexity.

Thus, there is a need for a technical solution with low computational complexity to draw, support or handle optical fibers and effective in reducing the attenuation in optical fibers.
SUMMARY
In an aspect of the present disclosure, an apparatus to levitate an optical fiber is disclosed. The apparatus having a tubular block defined by a central cavity and a plurality of slit walls. The tubular block has a reservoir that is adapted to store a fluid at a positive pressure. Each slit wall of the plurality of slit walls comprises one or more side slits and the plurality of slit walls defines a bottom slit such that the one or more side slits and the bottom slit provide one or more paths between the reservoir and the central cavity.

In another aspect of the present disclosure, a method to levitate an optical fiber is disclosed. The method has steps of creating a containment zone for the optical fiber in an apparatus to levitate the optical fiber to facilitate cooling of the optical fiber. For creating the containment zone, the method has step of directing, a fluid at a controlled mass flow rate to at least one slit of the one or more side slits and the bottom slit directly at the optical fiber and at least one slit of the one or more side slits and the bottom slit not directing the fluid at a controlled mass flow rate directly on the optical fiber. The method further has a step of directing, the fluid at the controlled mass flow rate to a first side of the optical fiber through at least one slit of the one or more side slits and the bottom slit and directing the fluid at the controlled mass flow rate to a second side of the optical fiber through at least one remaining slit of the one or more side slits and the bottom slit. The method further has a step of pulling the optical fiber through the containment zone in a non-contact manner.
BRIEF DESCRIPTION OF DRAWINGS
The following detailed description of the preferred aspects of the present disclosure will be better understood when read in conjunction with the appended drawings. The present disclosure is illustrated by way of example, and not limited by the accompanying figures, in which like references indicate similar elements.
FIG. 1A illustrates a cross-sectional front view of an apparats.
FIG. 1B illustrates another cross-sectional view of the apparatus.
FIG. 1C illustrates yet another cross-sectional view of the apparatus.
FIG. 2 illustrates an orientation of first and second slits and a bottom slit.
FIG. 3 illustrates another orientation of first and second slits and a bottom slit.
FIG. 4 illustrates yet another orientation of first and second slits and a bottom slit.
FIG. 5 illustrates yet another orientation of first and second slits and a bottom slit
FIG. 6 illustrates yet another orientation of first and second slits and a bottom slit.
FIG. 7 illustrates yet another orientation of first and second slits and a bottom slit.
FIG. 8 illustrates a setup for manufacturing an optical fiber.
FIG. 9 illustrates a cooling tube of the setup.
FIG. 10 illustrates a flowchart of a method for manufacturing an optical fiber by using the setup of FIG. 8.
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.

FIG. 1A illustrates a cross-sectional front view of an apparats 100. The apparatus 100 may be adapted to pneumatically levitate an optical fiber such that the optical fiber can be turned in a non-contact manner. Further, the apparatus 100 may be adapted to create a fluid flow pattern such that the optical fiber levitates (i.e., the optical fiber may be suspended in air in a non-contact manner) without touching any surface of the apparatus 100 by virtue of non-contact pneumatic levitation. The apparats 100 may have a tubular block 102. The tubular block 102 may have a plurality of outer walls of which first through third outer walls 104a-104c are shown, a plurality of slit walls of which first and second slit walls 106a and 106b are shown, and a reservoir 108. Specifically, the first through third outer walls 104a-104c and the first and second slit walls 106a and 106b defines the reservoir 108. As illustrated, the first through third walls 104a-104c may form three sides of the rectangular shaped tubular block 102 such that a fourth side of the tubular block 102 may be a partially opened side. Specifically, the first wall 104a and the third wall 104c may be vertical side walls and the second wall 104b may be a horizontal bottom wall of the tubular block 102. The first wall 104a may have a first end 104aa and a second end 104ab, the second wall 104b may have a first end 104ba and a second end 104bb, and the third wall 104c may have a first end 104ca and a second end 104cb. As illustrated, the second end 104ab of the first wall 104a may be attached to the first end 104ba of the second wall 104b. Further, the second end 104bb of the second wall 104b may be attached to the second end 104cb of the third wall 104c thus forming the tubular block 102. The first slit wall 106a may have a first end 106aa and a second end 106ab. Similarly, the second slit wall 106b may have a first end 106ba and a second end 106bb. Specifically, the first end 106aa of the first slit wall 106a may be attached to the first end 104aa of the first side wall 104a. Similarly, the first end 106ab of the second slit wall 106b may be attached to the first end 104ca of the third side wall 104c. As illustrated, the first slit wall 106a and the second slit wall 106b may extend from the first end 104aa of the first wall 104a and the first end 104ca of the third wall 104c, respectively, such that the first slit wall 106a and the second slit wall 106b makes a slit wall angle with respect to a longitudinal axis 118 of the tubular block 102. In some aspects of the present disclosure, the slit wall angle may be in a range of 5 degrees to 60 degrees. As illustrated, the first and second slit walls 106a and 106b may define a central cavity 112 of the apparatus 100. Specifically, the central cavity 112 may be adapted to facilitate in creation of a containment zone 114 for the optical fiber to levitate. The containment zone 114 may be a zone that may facilitate in cooling down the optical fiber by levitating the optical fiber for a predefined time. In other words, the optical fiber may be levitated in the containment zone 114 for the predefined time such that the optical fiber is substantially cooled down.

The first slit wall 106a may have one or more side slits of which a first side slit 116a is shown. Similarly, the second slit wall 106b may have one or more side slits of which a second side slit 116b is shown. As illustrated, the first side slit 116a may be an opening and/or an orifice in the tubular block 102 that may extend from a first surface of the first slit wall 106a (i.e., proximal to the reservoir 108) to a second surface of the first slit wall 106a (i.e., proximal to the central cavity 112). Similarly, the second side slit 116b may be an opening and/or an orifice in the tubular block 102 that may extend from a first surface of the second slit wall 106b (i.e., proximal to the reservoir 108) to a second surface of the second slit wall 106b (i.e., proximal to the central cavity 112). In other words, the first and second side slits 116a and 116b may be passage points of a fluid 120 held in the reservoir 108. Specifically, the first and second side slits 116a and 116b may be connected to the reservoir 108 (at a fluid entry end) and to the central cavity 112 (at a fluid exit end) to facilitate containment of the fluid 120 inside the central cavity 112 to pneumatically levitate the optical fiber. In some aspects of the present disclosure, the first and second side slits 116a and 116b may be adapted to stabilize flow patterns formed by all sources of the fluid 120 (i.e., the reservoir 108 and surrounding atmosphere). Although FIG. 1 illustrates that the first and second slit walls 106a and 106b includes one side slit (i.e., the first side slit 116a and the second side slit 116b, respectively), 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, the first and second slit walls 106a and 106b may include more than one side slits without deviating from the scope of the present disclosure. In such a scenario, each side slit may be adapted to perform one or more functionalities in a manner similar to the functionalities of the first side slit 116a and the second side slit 116b as described herein. In some aspects of the present disclosure, the first and second slit walls 106a and 106b may have a predefined side slit angle with respect to a longitudinal axis 118 of the tubular block 102. The predefined side slit angle may be in a range of 5 degrees to 90 degrees.

Further, the second ends 106ab and 106bb of the first slit wall 106a and the second slit wall 106b, respectively, may be substantially parallel to one another thus leaving a small separation thereto to form a bottom slit 122. Specifically, the bottom slit 122 may be an opening and/or an orifice in the tubular block 102 that extends from a bottom surface of the tubular block 102 (i.e., proximal to the reservoir 108) towards the central cavity 112. The bottom slit 122 may be adapted to provide the controlled mass flow rates to create the containment zone 114 such that the optical fiber levitates in the containment zone 114 by virtue of the controlled mass flow rates. As illustrated, the second ends 106ab and 106bb of the first slit wall 106a and the second slit wall 106b, respectively, may be substantially parallel to one another thus forming the bottom slit 122 that is a V-shaped groove. In some aspects of the present disclosure, the V-shaped groove of the bottom slit 122 may have a predefined bottom slit angle with respect to the longitudinal axis 118 of the tubular block 102. The predefined bottom slit angle may be in a range of 30 degrees to 120 degrees. In an exemplary aspect of the present disclosure, when the predefined bottom slit angle of the bottom slit 122 is 30 degrees, the predefined side slit angle of the first and second side slits 116a and 116b is 45 degrees. In another exemplary aspect of the present disclosure, when the predefined bottom slit angle of the bottom slit 122 is 60 degrees, the predefined side slit angle of the first and second side slits 116a and 116b is 40 degrees. In yet another exemplary aspect of the present disclosure, when the predefined bottom slit angle of the bottom slit 122 is 90 degrees, the predefined side slit angle of the first and second side slits 116a and 116b is 90 degrees. In yet another exemplary aspect of the present disclosure, when the predefined bottom slit angle of the bottom slit 122 is 100 degrees, the predefined side slit angle of the first and second side slits 116a and 116b is -45 degrees.

The reservoir 108 may be defined by the first through third walls 104a-104c and the first and second slit walls 106a and 106b of the tubular block 102. The reservoir 108 may be adapted to store the fluid 120 and further release the fluid 120 at controlled mass flow rates to pneumatically levitate the optical fiber in the containment zone 114. In other words, the reservoir 108 may facilitate in controlled flow of the fluid 120 with varying mass flow rates as per requirement to pneumatically levitate the optical fiber in the containment zone 114. In some aspects of the present disclosure, the fluid 120 may be adapted to transfer a momentum and/or a pressure to a surface of the optical fiber to pneumatically levitate the optical fiber in a non-contact manner and to facilitate in avoiding contact of the optical fiber to any surface of the apparatus 100. In some aspects of the present disclosure, the fluid 120 may include, but is not limited to, combination of gases, oxygen, and the like. Preferably, the fluid 120 may be air. Aspects of the present disclosure are intended to include and/or otherwise cover any type of the fluid 120 that may enable levitation of the optical fiber, including known, related, and later developed fluids.

The fluid 120 may be held in the reservoir 108 at a positive pressure. Specifically, the positive pressure of the fuid 118 maintained in the reservoir 108 may enable momentum transfer to the surface of the optical fiber. The positive pressure of the fluid 120 may enable momentum transfer to the optical fiber by use of controlled gas flow thus making the optical fiber to remain in a non-contact state when the draw tower is in operation. However, when the fluid 120 is not maintained at a positive pressure, the optical fiber may not levitate and may touch the first and second slit walls 106a and 106b of the tubular block 102.
FIG. 1B illustrates another cross-sectional view of the apparatus 100. The first and second side slits 116a and 116b may define one or more side entry areas and the bottom slit 122 may define a bottom entry area, Specifically, the first side slit 116a and the second side slit 116b may define a first side entry area 124 and a second side entry area 126, respectively. The first side entry area 124 may be an area formed at an interface where the first side slit 116a opens inside the central cavity 112. Similarly, the second side entry area 126 may be an area formed at an interface where the second side slit 116b opens inside the central cavity 112. In some aspects of the present disclosure, the first side entry area 124 and the second side entry area 126 may be adapted to provide an opening area through which the fluid 120 can be flown thus maintaining the controlled mass flow rates to create the containment zone 114. Furthermore, the first side slit 116a and the second side slit 116b may define a first side path area 128 and a second side path area 130. The first side path area 128 and the second side path area 130 may be formed between an entry point of the reservoir 108 to the central cavity 112 to enable flow of the fluid 120 from the reservoir 108 to the first side entry area 124 and the second side entry area 126 at controlled mass flow rates to create the containment zone 114.

The bottom slit 122 may define a bottom entry area 132 that may be an area formed at an interface where the bottom slit 122 opens inside the central cavity 112. In some aspects of the present disclosure, the bottom entry area 132 may be adapted to provide an opening area through which the fluid 120 can be flown, thus maintaining the controlled mass flow rates to create the containment zone 114. Furthermore, the bottom slit 122 may define a bottom path area 134 that may be an area defined by a bottom entry area extending from the bottom surface of the tubular block 102 to (i.e., proximal to the reservoir 108) towards the central cavity 112. Specifically, the bottom path area 134 may be formed between an entry point of the reservoir 108 to the central cavity 112 to enable flow of the fluid 120 from the reservoir 108 to the bottom entry area 132 at controlled mass flow rates to create the containment zone 114. In some aspects of the present disclosure, the bottom entry area 132 may be less than the first and second side entry areas 124 and 126.
Specifically, the first path area 128, the second path area 130, and the bottom path area 134 may be defined as a controlled flow of the fluid 120 from the reservoir 108 at positive pressure to the central cavity 112 of the tubular block 102. Further, the first path area 128, the second path area 130, and the bottom path area 134 may facilitate in creation of differential mass flow for the fluid 120 in the central cavity 112 of the tubular block 102 to achieve non-contact levitation of the optical fiber. In other words, the first path area 128, the second path area 130, and the bottom path area 134 may be formed by virtue of the controlled flow of the fluid 120 from the reservoir 108 to the central cavity 112 of the tubular block 102. In some aspects of the present disclosure, the first path area 128, the second path area 130, and the bottom path area 134 may be formed based on an equation: 0.1< Ai/ As < 3, where As is side slit flow area.

In some aspects of the present disclosure, the first path area 128 and the first entry area 124, the second path area 130 and the second entry area 126, and the bottom path area 134 and the bottom entry area 132 may have first through third ratios, respectively. Specifically, the first through third ratios may be defined by: Ai2 / Ao2,
where, Ai refers to an input flow area (square meter (m2), square feet (ft2)); and
Ao refers to a flow area at the optical fibre interaction with the fluid 120 (m2, ft2).
Specifically, the first through third ratios may be in a range of 0.045 to 0.45. In some aspects of the present disclosure, at least one of the first side slit 116a, the second side slit 116b, and the bottom slit 122 may have a variable dimension such that the entry area the first side slit 116a, the second side slit 116b, and the bottom slit 122 is greater than the path area. Specifically, the first entry area 124 may be greater than the first path area 128, the second entry area 126 may be greater than the second path area 130, and the bottom entry area 132 may be greater than the bottom path area 134. Specifically, the first entry area 124, the second entry area 126, and the bottom entry area 132 may be greater than the first path area 128, the second path area 130, and the bottom path area 134, respectively, to facilitate in creation of differential mass flow rates to achieve a stable flow pattern thus causing the optical fiber to levitate. In some aspects of the present disclosure, the first side slit 116a and the second side slit 116b may have a width that may be in a range of 200 micrometres (µm) to 500 µm. Preferably, the width of the first side slit 116a and the second side slit 116b may be in a range of 200 µm to 333 µm.

As illustrated, the bottom slit 122 may be defined by the second ends 106ab and 106bb of the first and second slit walls 106a and 106b, respectively. Specifically, the bottom slit 122 may be a V-shaped groove that may be defined by the first and second slit walls 106a and 106b that are tilted walls of the tubular block 102. In some embodiments of the present disclosure, the bottom slit 122 may have a width that may be in a range of 60 micrometres (µm) to 150 µm.

In some aspects of the present disclosure, a flow rate Q1 of the bottom slit 122 may be given by an equation that states:
Q1=Cd?Aiv(2(Fnet/LD-Pi)/?(((Ai)^2/(A0)^2) (Cp-4Cpsin^2 (?)-1)+1) )
where,
p = pressure (Pa, psf (lb/ft2)); 0.01 to 4 bar
? = density (kg/m3, slugs/ft3); 0.08 to 1.4 (kg/m3)
v = flow velocity (m/s, ft/s); 50m/s to 900 m/s
Q = flow rate (m3/s, ft3/s);
Ai =input flow area (m2, ft2); 0.000012 to 0.00005 (m2)
Ao = flow area at the fibre interaction with gas (m2, ft2); 0.00016 to o.2m2
cd = discharge coefficient; 0.9-1.2
cp = pressure coefficient; -3 to 1
L = length of the orifice [mm], 400-500 [mm]
D = Diameter of the orifice, 30µ -125µ
Fnet = net force acting on the fibre in the direction of the motion of fibre; 0.15 - 0.25
Pi= input pressure; 0.01 to 4 bar
Qi = input mass flow rate; 0.5 to 2 (kg.m3/s)
? = angle at which the gas hitting on to the surface of the bare optical fibre.: 0 degree to 90 degree

FIG. 1C illustrates yet another cross-sectional view of the apparatus 100. As illustrated, the containment zone 114 may be created by virtue of the controlled mass flow rates of the fluid 120 from the first side slit 116a, the second side slit 116b, and the bottom slit 122.

In operation, prior to letting an optical fiber 136 enter the apparatus 100, the containment zone 114 may be created. To create the containment zone 114, the fluid 120 may be flown from the reservoir 108 into at least one slit (e.g., the first side slit 116a, the second side slit 116b, and the bottom slit 122). In some aspects of the present disclosure, the fluid 120 may be flown from the reservoir 108 into the first side slit 116a, the second side slit 116b, and the bottom slit 122 at controlled mass flow rates. Specifically, the fluid 120 may be directed at the controlled mass flow rate to at least one slit of the first and second side slits 116a and 116b and the bottom slit 122 directly at the optical fiber 136. Further, the fluid 120 may not be directed on the optical fiber 136 through at least one slit of the first and second side slits 116a and 116b and the bottom slit 122. Furthermore, to create the containment zone 114, the fluid 120 may be directed at the controlled mass flow rate to a first side of the optical fiber 136 through at least one slit of the first and second side slits 116a and 116b and the bottom slit 122 and further, the fluid 120 may be directed at the controlled mass flow rate to a second side of the optical fiber 802 through at least one remaining slit of the first and second side slits 116a and 116b and the bottom slit 122 to create the containment zone 114. Specifically, a mass flow rate Q2 of the fluid 120 from the second side slit 116b may be greater than the mass flow rate Q1 of the fluid 120 from the bottom slit 122 that may be required to just lift the optical fiber 136 during drawing of the optical fiber 136 from different directions. In some aspects of the present disclosure, the fluid 120 from the first side slit 116a may have a mass flow rate Q2. The containment zone 114 may be created by virtue of the difference in the mass flow rates of the first and second side slits 116a and 116b compared to the bottom slit 122. Specifically, the first side slit 116a, the second side slit 116b, and the bottom slit 122 may be pumped with the fluid 120 having differential mass flow rates such that the mass flow rates after exiting the first side slit 116a, the second side slit 116b, and the bottom slit 122 may combine with each other to form the containment zone 114. In some aspects of the present disclosure, the difference in the mass flow rates may be realized due to a difference in the first and second ratio Ai/As. The optical fiber 136 in containment zone 114 may be substantially parallel to an axis of the tubular block 102 that defines a direction of levitation of the optical fiber 136 in the containment zone 114.In some aspects of the present disclosure, the mass flow rates Q2 of the first and second side slits 116a and 116b may be equal and the mass flow rate Q1 of the bottom slit 122 may be different from the mass flow rates of the first and second side slits 116a and 116b.

The containment zone 114 may further receive the fluid 120 from a surrounding atmosphere. The fluid 120 from the surrounding atmosphere may have a mass flow rate Qa such that the mass flow rate Q1 of the fluid 120 from the bottom slit 122, the mass flow rate Q2 of the fluid 120 from the first and second side slits 116a and 116b, and the mass flow rate Qa of the fluid 120 from the surrounding atmosphere are related as Q2 > Q1 > Qa. In other words, the mass flow rate Q2 of the fluid 120 from the first and second side slits 116a and 116b may be greater than the mass flow rate Q1 of the fluid 120 from the bottom slit 122. Further, the mass flow rate Q1 of the fluid 120 from the bottom slit 122 may be greater than the the mass flow rate Qa of the fluid 120 from the surrounding atmosphere. Specifically, the aforementioned relation between the mass flow rate Q1 of the fluid 120 from the bottom slit 122, the mass flow rate Q2 of the fluid 120 from the first and second side slits 116a and 116b, and the mass flow rate Qa of the fluid 120 from the surrounding atmosphere may ensure stable levitation of the optical fiber 136. However, when the difference in the mass flow rates of the first and second side slits 116a and 116b compared to the bottom slit 122 is not maintained, in such scenario, the optical fiber 136 may not levitate and hence the optical fiber 136 may touch a surface of the bottom slit 122 thus adding up more attenuation inside the optical fiber 136. In some aspects of the present disclosure, the mass flow rates of the fluid 120 through the first side slit 116a, the second side slit 116b, and the bottom slit 122 from the reservoir 108 may be greater than 0.5 Kilogram/meter cubic/second (kg/m3/s). In some aspects of the present disclosure, the mass flow rates of the fluid 120 through the bottom slit 122 may be in a range of 0.5 kg/m3/s to 2 kg/m3/s. Preferably, the mass flow rate of the fluid 120 through the bottom slit 122 may be in a range of 0.78 kg/m3/s to 1.86 kg/m3/s. In some aspects of the present disclosure, the mass flow rates of the fluid 120 through the first side slit 116a and the second side slit 116b may be in a range of 2.59 kg/m3/s to 6.19 kg/m3/s. Specifically, the mass flow rates of the fluid 120 through the first side slit 116a and the second side slit 116b may be 3.333 times greater than the mass flow rates of the fluid 120 through the bottom slit 122. The difference in the mass flow rates of the first side slit 116a, the second side slit 116b, and the bottom slit 122 may ensure stable levitation of the optical fiber 136. Further, once the containment zone 114 is created, the optical fiber 136, after exit from a draw furnace (not shown), may enter the apparatus 100. The optical fiber 136 may pneumatically levitate in the containment zone 114 of the apparatus 100 in a non-contact manner by virtue of the differential mass flow rates from the first side slit 116a, the second side slit 116b, and the bottom slit 122.

In some aspect of the present disclosure, for stable levitation of the optical fiber 136, the width of the bottom slit 122 may be in a range of 60 µm to 150 µm and the width of the first and second side slits 116a and 116b may be in a range of 200 µm to 500 µm. In one aspect of the present disclosure, for stable levitation of the optical fiber 136, the width of the bottom slit 122 is selected to be in the range of 60 µm to 100 µm and the width of the first and second side slits 116a and 116b is selected to be in the range of 200 µm to 333 µm. By virtue of the width of the bottom slit 122, the mass flow rate of the fluid 120 through the bottom slit 122 is in the range of 0.78 kg/m3/s to 1.86 kg/m3/s. Further, by virtue of the width of the first and second side slits 116a and 116b the mass flow rates of the fluid 120 through the first and second side slits 116a and 116b is 2.59 kg/m3/s to 6.19 kg/m3/s that is approximately 3.333 times greater that the mass flow rate of the fluid 120 through the bottom slit 122. Specifically, the variable dimension of at least one of the first side slit 116a, the second side slit 116b, and the bottom slit 122 may facilitate in stable levitation of the optical fiber 136.

FIG. 2 illustrates an orientation 200 of first and second slits and a bottom slit. In some aspects of the present disclosure, a tubular block 201 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 202a and a second slit wall 202b. Specifically, the first slit wall 202a and the second slit wall 202b may be arc shaped walls that may together form a U-shaped structure as opposed to a V-shaped structure formed by the first slit wall 106a and the second slit wall 106b of the tubular block 102 (as shown in FIG. 1A). The first slit wall 202a and the second slit wall 202b may have a first side slit 204a and a second side slit 204b, respectively. As illustrated, the first side slit 204a and the second side slit 204b may be disposed at a first predefined angle with respect to a longitudinal axis 206 of the tubular block 201. In some aspects of the present disclosure, the first predefined angle may be in a range of 5 degree to 90 degrees. Further, the first slit wall 202a and the second slit wall 202b may define a bottom slit 204c such that the fluid 120 may be flown through the first side slit 204a, the second side slit 204b, and the bottom slit 204c at differential mass flow rates thus creating a containment zone 208. The containment zone 208 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

FIG. 3 illustrates another orientation 300 of first and second slits and a bottom slit. In some aspects of the present disclosure, a tubular block 301 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 302a and a second slit wall 302b. Specifically, the first slit wall 302a and the second slit wall 302b may be arc shaped walls that may together form a U-shaped structure as opposed to the V-shaped structure formed by the first slit wall 106a and the second slit wall 106b of the tubular block 102 (as shown in FIG. 1A). The first slit wall 302a and the second slit wall 302b may have a first side slit 304a and a second side slit 304b, respectively. As illustrated, the first side slit 304a and the second side slit 304b may be disposed at an angle of 90 degrees with respect to a longitudinal axis 306 of the tubular block 301. Further, the first slit wall 302a and the second slit wall 302b may define a bottom slit 304c that may be substantially perpendicular to a longitudinal axis 306 of the tubular block 301 such that the fluid 120 may be flown through the first side slit 304a, the second side slit 304b, and the bottom slit 304c at differential mass flow rates thus creating a containment zone 308. The containment zone 308 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

FIG. 4 illustrates yet another orientation 400 of first and second slits and a bottom slit. In some aspects of the present disclosure, a tubular block 401 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 402a and a second slit wall 402b. Specifically, the first slit wall 402a and the second slit wall 402b may be similar to the first slit wall 106a and the second slit wall 106b of the tubular block 102 (as shown in FIG. 1A). The first slit wall 402a and the second slit wall 402b may have a first side slit 404a and a second side slit 404b, respectively. As illustrated, the first side slit 404a and the second side slit 404b may be disposed at a second predefined angle with respect to a horizontal axis of the tubular block 401. In some aspects of the present disclosure, the second predefined angle may be in a range of 5 degrees to 90 degrees. Further, the first slit wall 402a and the second slit wall 402b may define a bottom slit 404c that may be substantially perpendicular to a longitudinal axis 406 of the tubular block 401 such that the fluid 120 is flown through the first side slit 404a, the second side slit 404b, and the bottom slit 404c at differential mass flow rates thus creating a containment zone 406. The containment zone 408 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

FIG. 5 illustrates yet another orientation 500 of first and second slits and a bottom slit. A tubular block 501 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 502a and a second slit wall 502b. Specifically, the first slit wall 502a and the second slit wall 502b may be similar to the first slit wall 106a and the second slit wall 106b of the tubular block 102 (as shown in FIG. 1A). The first slit wall 502a and the second slit wall 502b may have a first side slit 504a and a second side slit 504b, respectively. As illustrated, the first side slit 504a and the second side slit 504b may be disposed at an angle of 90 degrees with respect to a longitudinal axis of the tubular block 501. Further, the first slit wall 502a and the second slit wall 502b may define a bottom slit 504c that may be substantially perpendicular to a longitudinal axis 506 of the tubular block 501 such that the fluid 120 may be flown through the first side slit 504a, the second side slit 504b, and the bottom slit 504c at differential mass flow rates thus creating a containment zone 506. The containment zone 506 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

FIG. 6 illustrates yet another orientation 600 of first and second slits and a bottom slit. A tubular block 601 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 602a and a second slit wall 602b. Specifically, the first slit wall 602a and the second slit wall 602b may be similar to the first slit wall 106a and the second slit wall 106b of the tubular block 102 (as shown in FIG. 1A). However, the first slit wall 602a may have a first portion 602aa and a second portion 602ab such that the first portion 602aa is a vertical portion of the first slit wall 602a and the second portion 602ab is a tilted portion of the first slit wall 602a. Similarly, the second slit wall 602b may have a first portion 602ba and a second portion 602bb such that the first portion 602ba is a vertical portion of the second slit wall 602b and the second portion 602bb is a tilted portion of the second slit wall 602b. The first slit wall 602a and the second slit wall 602b may have a first side slit 604a and a second side slit 604b, respectively. As illustrated, the first side slit 604a and the second side slit 604b may be disposed at an interface of the first and second portions 602aa and 602ab of the first slit wall 602a and at an interface of the first and second portions 602ba and 602bb of the second slit wall 602b, respectively. Specifically, the first side slit 604a and the second side slit 604b may be disposed at a third predefined angle with respect to a longitudinal axis 606 of the tubular block 601. In some aspects of the present disclosure, the third predefined angle may be in a range of 5 degrees to 90 degrees. Further, the first slit wall 602a and the second slit wall 602b may define a bottom slit 604c that may be substantially perpendicular to the horizontal axis of the tubular block 600 such that the fluid 120 is flown through the first side slit 604a, the second side slit 604b, and the bottom slit 604c at differential mass flow rates thus creating a containment zone 608. The containment zone 608 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

FIG. 7 illustrates yet another orientation 700 of first and second slits and a bottom slit. A tubular block 701 that may be functionally similar to the tubular block 102 (as shown in FIG. 1A) may have a first slit wall 702a and a second slit wall 702b. Specifically, the first slit wall 702a and the second slit wall 702b may be similar to the first slit wall 602a and the second slit wall 602b (as shown in FIG. 6). The first slit wall 702a and the second slit wall 702b may have a first side slit 704a and a second side slit 704b, respectively. As illustrated, the first side slit 704a and the second side slit 704b may be disposed at an angle of 180 degrees with respect to a horizontal axis of the tubular block 701. Further, the first slit wall 702a and the second slit wall 702b may define a bottom slit 704c that may be substantially perpendicular to a longitudinal axis 706 of the tubular block 701 such that the fluid 120 may be flown through the first side slit 704a, the second side slit 704b, and the bottom slit 704c at differential mass flow rates thus creating a containment zone 708. The containment zone 708 may be similar to the containment zone 114 (as shown in FIG. 1A) that may facilitate levitation of the optical fiber 136 in a non-contact manner.

Specifically, a change of a shape and angle of the slits (i.e., the first side slit 116a, 204a, 304a, 404a, 504a, 604a, and 704a, the second side slit 116b, 204b, 304b, 404b, 504b, 604b, and 704b, and the bottom slit 122, 204c, 304c, 404c, 504c, 604a, and 704a) and combination of different shapes with different orientations may ensure a stable levitation of the optical fiber 136 irrespective of the mass flow rates of the fluid 120 above minimum mass flow rates.

In one aspect of the present disclosure, FIG. 8 illustrates a setup 800 for manufacturing an optical fiber 802. The setup 800 may have a furnace 804, a plurality of apparatuses of which first through sixth apparatuses 806a-806f are shown, a coating section 808, a plurality of rollers of which first through third rollers 810a-810c are shown, and a spool 812. The furnace 804 may have a glass preform 814 from which the optical fiber 802 may be manufactured. As illustrated, the first through sixth apparatuses 806a-806f may be arranged in a way that the first apparatus 806a, the third apparatus 806c, and the fifth apparatus 896e may be horizontally aligned with each other and the second apparatus 806b, the fourth apparatus 806d, and the sixth apparatus 896f may be horizontally aligned with each other. The first apparatus 806a and the second apparatus 806b may be arranged opposite to each other such that the optical fiber 802 exiting from the first apparatus 806a enters the second apparatus 806b. Specifically, the optical fiber 802 (i.e., a bare optical fiber) may enter the first apparatus 806a at a temperature that may be in a range of 1050 Degree Celsius (°C) to 1400 °C. Similarly, the second apparatus 806b and the third apparatus 806c may be arranged opposite to each other such that the optical fiber 802 exiting from the second apparatus 806b enters the third apparatus 806c. Similarly, the third apparatus 806c and the fourth apparatus 806d may be arranged opposite to each other such that the optical fiber 802 exiting from the third apparatus 806c enters the fourth apparatus 806d. Similarly, the fourth apparatus 806d and the fifth apparatus 806e may be arranged opposite to each other such that the optical fiber 802 exiting from the fourth apparatus 806d enters the fifth apparatus 806e. Similarly, the fifth apparatus 806e and the sixth apparatus 806f may be arranged opposite to each other such that the optical fiber 802 exiting from the fifth apparatus 806e enters the sixth apparatus 806f. Although FIG. 8 illustrates that the plurality of apparatuses includes six apparatuses (i.e., the first through sixth apparatuses 806a-806f), 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, the plurality of apparatuses may include any number of apparatuses without deviating from the scope of the present disclosure. In such a scenario, each apparatus may be adapted to perform one or more functionalities in a manner similar to the functionalities of the first through sixth apparatuses 806a-806f as described herein.

As illustrated, the first through sixth apparatuses 806a-806f may be adapted to bend the optical fiber 802 from 1° to 270° in a non-contact manner. Specifically, the tubular block (e.g., the tubular blocks 102, 201, 301, 401, 501, 601, 701) of the first through sixth apparatuses 806a-806f may have an aerodynamic bearing radius of curvature. The aerodynamic bearing radius of curvature of the tubular block (e.g., the tubular blocks 102, 201, 301, 401, 501, 601, 701) may be defined as a minimum bend radius (MBR) of the optical fiber 802 below which the optical fiber 802 may break. Specifically, the aerodynamic bearing radius of curvature of the tubular block (e.g., the tubular blocks 102, 201, 301, 401, 501, 601, 701) may facilitate to bend and/or change a path of the optical fiber 802 through the arrangement of the first through sixth apparatuses 806a-806f to form a desired radius of curvature. In some aspects of the present disclosure, the aerodynamic bearing radius of curvature may be in a range of 55 mm to 100 mm. The aerodynamic bearing radius of curvature in the range of 55 mm to 100 mm enables bending and/or changing the path of the optical fiber 802 without breaking the optical fiber 802.

Further, the optical fiber 802 may be pulled through the first through sixth apparatuses 806a-806f such that a resident time of the optical fiber 802 in containment zones (similar to the containment zone 114 of the apparatus 100 as described in FIG. 1A) of each apparatus of the first through sixth apparatuses 806a-806f may be a function of a speed of pulling the optical fiber 802 and a length of each apparatus of the first through sixth apparatuses 806a-806f. Specifically, a residence time for optimal cooling of the optical fiber 802 may be determined by using an equation that states:
The residence time = a circumferential length of each apparatus of the first through sixth apparatuses 806a-806f / the speed of pulling the optical fibre 802.
In some aspects of the present disclosure, the residence time may be in a range of 6 milliseconds (ms) to 250 ms.
Specifically, the optical fiber 802 may be cooled by increasing a path length and the residence time of the optical fiber inside a cooling tube 900 (as shown later in FIG. 9) formed between adjacent apparatuses of the first through sixth apparatuses 806a-806f. Specifically, for manufacturing of ultra-low attenuation optical fibers, a temperature of the optical fiber 802 must be reduced as slowly as possible in a controlled manner in order to achieve less added s tress and less density fluctuations inside the optical fiber 802. Thus, the cooling tube 900 may facilitate to draw the optical fiber 802 at a higher speed while cooling the optical fiber 802 slowly without increasing a height of the setup 800.

The coating section 808 may be disposed adjacent to the sixth apparatus 806f such that the optical fiber 802 passes through the coating section 808 and is coated with a coating material. Specifically, prior to entering the coating section 808, the optical fiber 802 may be cooled down to an ambient temperature by virtue of the first through sixth apparatuses 806a-806f. The coating material may include, but not is limited to, Ultraviolet (UV) acrylates, silicone, hard clad (fluorinated acrylate), polyimide, and the like. Aspects of the present disclosure are intended to have and otherwise cover any type of the coating material for coating the optical fiber 802, including known, related, and later developed materials. The first through third rollers 810a-810c may be adapted to receive the optical fiber 802 such that the optical fiber 802 coated with the coating material may passed to the spool 812 and the optical fiber 802 may be winded onto the spool 812. Although FIG. 8 illustrates that the plurality of rollers includes three rollers (i.e., the first through third rollers 810a-810c), 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, the plurality of rollers may include any number of rollers without deviating from the scope of the present disclosure.

FIG. 9 illustrates the cooling tube 900 of the setup 800. The optical fiber 802 (i.e., a bare optical fiber) may enter the first apparatus 806a. Further, the second apparatus 806b may be arranged opposite to the first and the third apparatus 806c such that the optical fiber 802 exiting from the first apparatus 806a may bend and enter the second apparatus 806b and further exits from the second apparatus 806b to bend and enter the third apparatus 806c. The optical fiber 802 may be cooled by increasing the path length and the residence time of the optical fiber inside the cooling tube 900 formed by the arrangement of the first through third apparatuses 806a-806c. The cooling tube 900 may facilitate to draw the optical fiber 802 at a higher speed while cooling the optical fiber 802 slowly to reduce a Rayleigh scattering in the optical fiber 802 and thus producing an ultra low loss optical fiber without increasing the height of the setup 800 (as shown in FIG. 8).

FIG. 10 illustrates a flowchart of a method 1000 for manufacturing the optical fiber 802 by using the setup 800 of FIG. 8.

At step 1002, the optical fiber 802 is drawn from the glass preform 814 provided in the furnace 804.

At step 1004, a containment zone (e.g., the containment zone 114 of the apparatus 100) is created. To create the containment zone 114, the fluid 120 is flown from the reservoir 108 into at least one slit (e.g., the first side slit 116a, the second side slit 116b, and the bottom slit 122). Specifically, the fluid 120 may be flown from the reservoir 108 into the first side slit 116a, the second side slit 116b, and the bottom slit 122 at controlled mass flow rates.
At step 1006, the fluid 120 is directed at the controlled mass flow rate to at least one slit of the first and second side slits 116a and 116b and the bottom slit 122 directly at the optical fiber 802 and further the fluid 120 is not directed directly on the optical fiber 802 through at least one slit of the first and second side slits 116a and 116b and the bottom slit 122, the fluid 120.

At step 1008, the fluid 120 is directed at the controlled mass flow rate to a first side of the optical fiber 802 through at least one slit of the first and second side slits 116a and 116b and the bottom slit 122 and further, the fluid 120 is directed at the controlled mass flow rate to a second side of the optical fiber 802 through at least one remaining slit of the first and second side slits 116a and 116b and the bottom slit 122 to create the containment zone 114.

At step 1010, once the containment zone 114 is created, the optical fiber 802 enters the apparatus 100. The optical fiber 802 levitates in the containment zone 114 in a non-contact manner by virtue of the differential mass flow rates for a predefined time.

At step 1012, the optical fiber 802 is cooled down to an ambient temperature in the cooling tube 900.

At step 1014, after cooling the optical fiber 802, the optical fiber 802 is passed through the coating section 808 such that the optical fiber 802 is coated with the coating material.

At step 1016, the optical fiber 802 is winded on the spool 812.

Thus, the setup 800 using the first through sixth apparatuses 806a-806f may increase a fiber drawing capacity, without increasing a height of the setup 800 by virtue of the arrangement of the first through sixth apparatuses 806a-806f. Further, the setup 800 using the first through sixth apparatuses 806a-806 may facilitate in production of ultra-low attenuation fibres as the optical fiber 802 are levitated in air while the cooling process. Moreover, the first and second side slits 116a and 116b and the bottom slit 122 provides flexibility to change a diameter (e.g., 125µm, 100µm, and 80µm) of the optical fiber 802 by varying the mass flow rates of the fluid 120. The first through sixth apparatuses 806a-806f of the setup 800 further facilitate to bend and/or change path of the optical fiber 802 in a non-contact manner without use of any external devices that reduces operating cost of the setup 800 and further a manufacturing cost of the optical fiber 802.

While various aspects of the present disclosure have been illustrated and described, it will be clear that the present disclosure is not limited to these aspects only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the present disclosure, as described in the claims. Further, unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements.
, C , Claims:I/We claim(s)

1. An apparatus (100) to levitate an optical fiber (136), the apparatus (100) comprising:
a tubular block (102) defined by a central cavity (112) and a plurality of slit walls (106a, 106b), wherein the tubular block (102) comprises a reservoir (108) that is adapted to store a fluid (120) at a positive pressure; and
wherein each slit wall of the plurality of slit walls (106a, 106b) comprises one or more side slits (116) and the plurality of slit walls (106a, 106b) defines a bottom slit (122) such that the one or more side slits (116a, 116b) and the bottom slit (122) provide one or more paths between the reservoir (108) and the central cavity (112).

2. The apparatus as claimed in claim 1, wherein (i) the one or more side slits (116) comprising first and second side slits (116a, 116b) such that the first and second side slits (116a, 116b) defines first and second side entry areas (124,126) and (ii) the bottom slit (122) defines a bottom entry area, wherein the bottom slit entry area is less than the first and second side slit entry area (124, 126).

3. The apparatus as claimed in claim 2, wherein at least one slit of the first and second side slits (116a, 116b) and the bottom slit (122) has a variable dimension such that an entry area of the at least one slit is greater than a path area of the at least one slit.

4. The apparatus as claimed in claim 1, wherein the tubular block (102) has a radius of curvature along a length of the tubular block (102), wherein the radius of curvature is greater than or equal to 25 mm.

5. The apparatus as claimed in claim 1, further comprising a containment zone (114) such that the optical fiber (136) in the containment zone (114) is substantially parallel to an axis of the tubular block (102).

6. The apparatus as claimed in claim 1, wherein the fluid (120) is selected from one of, air, combination of gases, and oxygen.

7. The apparatus as claimed in claim 1, wherein a width of the bottom slit (122) is between 60 micrometres (µm) to 150 µm.

8. The apparatus as claimed in claim 2, wherein a mass flow rate (Q1) of the fluid (120) through the bottom slit (122) and a mass flow rate (Q2) of the fluid (120) through the first and second side slits (116a, 116b) is greater than 0.5 Kilogram/meter cubic/second (kg/m3/s).

9. The apparatus as claimed in claim 8, wherein the mass flow rate (Q1), the mass flow rate (Q2), and a mass flow rate (Qa) of the fluid (120) from a surrounding atmosphere is related as Q2 > Q1 > Qa.

10. The apparatus as claimed in claim 1, wherein the bottom slit (122) has a predefined bottom slit angle with respect to a longitudinal axis of the tubular block (102), wherein the predefined bottom slit angle is in a range of 30 degrees to 120 degrees.

11. The apparatus as claimed in claim 1, wherein the one or more side slits (116a, 116b) has a predefined side slit angle with respect to the longitudinal axis of the tubular block (102), wherein the predefined side slit angle is in a range of 5 degrees to 90 degrees.

12. A method to levitate an optical fiber (136), the method comprising:
creating a containment zone (114) for the optical fiber (136) in an apparatus (100) to levitate the optical fiber (136) to facilitate cooling of the optical fiber (136), wherein, for creating the containment zone (114), the method comprising:
directing, a fluid (120) at a controlled mass flow rate to at least one slit of the one or more side slits (116) and the bottom slit (122) directly at the optical fiber (136) and at least one slit of the one or more side slits (116) and the bottom slit (122) not directing the fluid (120) at a controlled mass flow rate directly on the optical fiber (136); and
directing, the fluid (120) at the controlled mass flow rate to a first side of the optical fiber (136) through at least one slit of the one or more side slits (116) and the bottom slit (122) and directing the fluid (120) at the controlled mass flow rate to a second side of the optical fiber (136) through at least one remaining slit of the one or more side slits (116) and the bottom slit (122); and
pulling the optical fiber (136) through the containment zone (114) in a non-contact manner.

13. The method as claimed in claim 12, wherein the fluid (120) is selected from one of, air, combination of gases, and oxygen.

14. The method as claimed in claim 12, wherein, prior to entering the apparatus (100), the optical fibre (136) is at temperature that is in a range of 1050 Degree Celsius (°C) and after exiting the apparatus (100), the optical fiber (136) is at a temperature that is in a range of 50 °C to 100 °C.

15. The method as claimed in claim 12, further comprising:
pulling the optical fiber (136) through the containment zone (114) such that a residence time of the optical fiber (136) in the apparatus (100) is a function of speed of pulling the optical fiber (136) and a length of the apparatus (100).

16. The method as claimed in claim 15, wherein the residence time is in a range of 6 milliseconds (ms) to 250 ms.

17. The method as claimed in claim 12, wherein a mass flow rate of the fluid (120) through the one or more side slits (116) and the bottom slit (122) is greater than 0.5 Kilogram/meter cubic/second (kg/m3/s).

18. The method as claimed in claim 12, wherein the bottom slit (122) has a predefined bottom slit angle with respect to a longitudinal axis of a tubular block (102) of the apparatus (100), wherein the predefined bottom slit angle is in a range of 30 degrees to 120 degrees.

19. The method as claimed in claim 1, wherein the one or more side slits (116) has a predefined side slit angle with respect to a longitudinal axis of the tubular block (102), wherein the predefined side slit angle is in a range of 5 degrees to 90 degrees.