The present disclosure relates to the field of optical fibre and, in particular, relates to a method for manufacturing an optical fibre through glass preform assembly using Rod-In-Cylinder process.
BACKGROUND
[0002] Over the last few years, there is a rapid increase in demand of optical fibre. Generally, optical fibre is a piece of glass or plastic used for data transmission using light pulses travelling along the optical fibre. Optical fibre is usually manufactured from a preform. Generally, preform is a piece of glass that is used to draw the optical fibre. Optical fibre preform is manufactured in large volume using Rod in cylinder process. Conventionally, there is a space or gap between core rod and solid quartz protruded ingot because the solid quartz ingot has a flat structure. Due to the flat structure of the solid quartz protruded ingot, it does not fit properly around chamfer region of cylinder. Generally, chamfer region of the cylinder is a tapered region which allows easy insertion of waveguide tubes. During heating for joining handle with cylinder, inner diameter of cylinder collapses to some extent. Chamfer region is provided to compensate this collapsing and for ease of inserting of waveguide tubes. During Rod in cylinder process, stretching of the cylinder is performed. During the stretching of hollow glass cylinder of glass preform assembly, vacuum is applied at top end of the hollow glass cylinder which acts as suction and aids in collapsing of gap within the cylinder. This further leads to misalignment of core clad ratio [D/d] due to non-standard positioning of core rods. Due to non-uniform gaps present within the hollow glass cylinder, core rod collapses in an uneven way along the length of cylinder which ultimately leads to shifting of the waveguide tube in the gap or space around the chamfer region. This eventually has a side effect of causing macro-bend failure in an optical fibre formed from optical fibre preform.

[0003] The prior art, US7143611B2 provides a "Rod-In-Tube optical fiber preform assembly and method having reduced movement". Embodiments of the invention include an optical fiber preform assembly and a method for making optical fiber using the preform assembly. The assembly includes a preform core rod, at least one over-clad tube formed around the preform core rod, a handle attached to one end of the over-clad tube, and a refractory material positioned in the over-clad tube between the preform core rod and the handle. The refractory material reduces, if not prevents movement of the preform core rod into the handle during the fiber draw process. Preferably, the refractory material is made of, e.g., magnesium oxide and/or aluminum oxide, and has a melting point, e.g., greater than approximately 2000 degrees Celsius. Since refractory based material needs to have a high melting point and is not an inclusive part of a spacer itself but rather a material positioned in between preform core rod and the handle, which makes this process an expensive process. Along with this it has one other limitation; the patent does not disclose anything regarding improvement in eliminating macro bend loss and other waveguide failure in an optical fiber. Another limitation is that patent does not disclose significant changes neither in quartz tube nor in handle to control core rod movement during rod in cylinder technique.
[0004] In light of the above stated discussion, there is a need for an efficient method for manufacturing the optical fibre that overcomes the above stated disadvantages.

OBJECT OF THE DISCLOSURE
[0005] A primary object of the present disclosure is to provide a glass preform assembly for manufacturing an optical fibre.
[0006] Another objective of the present disclosure is to provide the method of stretching and collapsing for manufacturing of an optical fibre using a Rod-In-Cylinder process.
[0007] Another obj ective of the present disclosure is to provide a glass preform assembly for manufacturing optical fiber with reduced macro-bend loss and other waveguide failure along the length of cylinder.
[0008] Another obj ective of the present disclosure is to provide a glass preform assembly for manufacturing an optical fiber where core - clad ratio along the length of cylinder is maintained.
[0009] Another obj ective of the present disclosure is to provide a glass preform assembly for manufacturing an optical fiber having uniform stretching ratio.
SUMMARY
[0010] In an aspect, the present disclosure provides a glass preform assembly for manufacturing an optical fibre. The glass preform assembly includes a solid glass core rod. In addition, the glass preform assembly includes at least one hollow glass over-clad tube. Further, the glass preform assembly includes a hollow glass cylinder. Furthermore, the glass preform assembly includes a top handle assembly and a bottom handle which are attached at the ends of the hollow glass cylinder. The solid glass core rod, the hollow glass over-clad tube and the hollow glass cylinder are of cylindrical shape. The hollow glass over-clad tube is concentric to the solid glass core rod. The hollow glass cylinder is concentric to the hollow slass over-clad tube. Moreover, the too handle

assembly includes a hollow top handle to which a holding tube and a solid quartz protruded ingot are placed. The solid quartz protruded ingot has a solid cylindrical region and a protruded region at one of its end and has one or more elongated slots running along the length of solid quartz protruded ingot. The top handle is situated at one end of the glass preform assembly. The protrusion is at one end of the solid quartz protruded ingot. The bottom handle is solid which is connected to the other end of the glass preform assembly. In an embodiment of the present disclosure, the solid cylindrical region of the solid quartz protruded ingot has diameter greater than diameter of the protrusion of the solid quartz protruded ingot.
[0011] In an embodiment of the present disclosure, the solid cylindrical region of the solid quartz protruded ingot and the protrusion of the solid quartz protruded ingot are connected to each other such that protrusion forms a composite part of cylindrical region to form a solid quartz protruded ingot.
[0012] In an embodiment of the present disclosure, the protrusion region fits perfectly into the tapered length chamfer region present inside the hollow glass cylinder.
[0013] In an embodiment of the present disclosure, the protruded region of the solid quartz protruded ingot has a length of about 15 +/-5 millimetres.
[0014] In an embodiment of the present disclosure, the protrusion in the solid quartz protruded ingot has an outer diameter determined through a formula: [cylinder ID-3mm] +/- 2mm.
[0015] In an embodiment of the present disclosure, the solid quartz protruded ingot cylindrical region has a length in range of about 135 +/- 20mm.

[0016] In an embodiment of the present disclosure, the solid quartz protruded ingot cylindrical region has an outer diameter of less than or equal to 78 millimetres.
[0017] In an embodiment of the present disclosure, the solid quartz protruded ingot has total length of 150 +/- 20 mm.
[0018] In an embodiment of the present disclosure, the one or more elongated slot regions are defined by at least one of 4 slots running across total length of the solid quartz protruded ingot. The one or more elongated slot regions are spaced 90 degree apart. The one or more elongated slot regions run longitudinally along the length of solid quartz protruded ingot.
[0019] In an embodiment of the present disclosure, the solid quartz protruded ingot maintains ratio of diameters of core and clad of an optical fibre during a Rod-In-Cylinder process and uniform stretching ratio along the length of cylinder which is equivalent to the initial length of the core rod to the final stretched length of the core rod.
[0020] In another aspect, the present disclosure provides a method of stretching and collapsing for manufacturing of an optical fibre using a Rod-In-Cylinder process. The method includes a first step of cleaning of a solid glass core rod, a hollow glass over-clad tube, and a hollow glass cylinder with the help of HF (Hydrofluoric acid) etching and purging of N2 (nitrogen) gas to remove any kind of dirt and other particles. In addition, the method includes another step of arranging the solid glass core rod, the hollow glass over-clad tube, and the hollow glass cylinder concentrically to form a glass preform assembly. Further, the method includes yet another step of suspending the glass preform assembly in the chuck, at the top with the help of top handle and bottom part of glass preform assembly with the bottom handle. There is preheating of the glass preform assembly in range of 800-1900 degree Celsius. Furthermore, the method includes vet another step of stretching and collapsing

simultaneously of the glass preform assembly in temperature range of 1900-2100 degree Celsius. Stretching is done with the help of applying force at the top handle of the glass preform assembly. Moreover, the method of collapsing of the glass preform assembly is done by applying vacuum pressure in range of 930-960 milli-bar from top of the glass preform assembly. The solid cylindrical region of the solid quartz protruded ingot has diameter greater than diameter of protrusion of the solid quartz protruded ingot. The glass preform is ready for drawing for manufacturing the optical fibre.
[0021] In an embodiment of the present disclosure, the one or more cleaning processes include HF (Hydrofluoric acid) etching and nitrogen gas purging to remove dirt particles which may further affect optical fiber quality.
[0022] In an embodiment of the present disclosure, the hollow glass cylinder has a chamfer region. The chamfer region prevents diameter of hollow glass cylinder from collapsing during heating in the Rod-In-Cylinder process during joining of the top handle which is attached at one end of the glass cylinder of glass preform assembly.
[0023] In an embodiment of the present disclosure, the protrusion of the solid quartz protruded ingot fits around a chamfer region in the hollow glass cylinder in between the glass core rod and the solid quartz protruded ingot. The protrusion inhibits or controls movement of the glass core rod. Due to stretching and vacuum suction application at top end of glass preform assembly, core rod which wants to maintain its position shifts upwards and this is controlled with the help of a protrusion. The inhibition movement of the glass core rod prevents the glass core rod to move from bottom of the hollow glass cylinder towards the chamfer region and eventually reduces macro-bend losses in optical fibre and other waveguide failure along the length of cylinder. This further ensures maintaining core-clad ratio and ensures uniform stretching along the length of cylinder thus maintaining appropriate ratio of initial length of core to the final stretched length of the core.

[0024] In an embodiment of the present disclosure, the Rod-In-Cylinder process stretches the hollow glass cylinder and maintains constant stretch ratio.
[0025] In an embodiment of the present disclosure, the solid quartz protruded ingot has total length of 150±20 mm.
STATEMENT OF THE DISCLOSURE
[0026] The present disclosure provides a glass preform assembly for manufacturing an optical fibre. The glass preform assembly includes a solid glass core rod. In addition, the glass preform assembly includes at least one over-clad hollow glass tube. Further, the glass preform assembly includes a hollow glass cylinder. Furthermore, the glass preform assembly includes a top handle assembly and a bottom handle. The solid glass core rod, hollow glass cylinder and the over-clad hollow glass tube has a cylindrical shape. The hollow glass cylinder is concentric to both solid glass core rod and the over-clad hollow glass tube. Moreover, the top handle assembly includes a holding tube. Also, the top handle assembly includes a solid quartz protruded ingot having a solid cylindrical region and a protruded region. The top handle is situated at the top end of the hollow glass cylinder or glass preform assembly. The protrusion is at least on one end of the solid quartz protruded ingot. The solid quartz protruded ingot has one or more slot regions running longitudinally over the length of the solid quartz protruded ingot.
BRIEF DESCRIPTION OF FIGURES
Having thus described the disclosure in general terms, reference will now be made to the accompanying figures, wherein:

[0027] FIG. 1 illustrates conventional solid quartz ingot having slots and a flat surface;
[0028] FIG. 2 illustrates a general overview of a glass preform assembly to manufacture an optical fibre, in accordance with various embodiments of the present disclosure;
[0029] FIG. 3 illustrates a close view of a solid quartz protruded ingot of the glass preform assembly, in accordance with an embodiment of the present disclosure; and
[0030] FIG. 4 illustrates a flow chart depicting a method of stretching and collapsing to manufacture the optical fibre using a Rod -In-Cylinder process, in accordance with various embodiments of the present disclosure.
[0031] It should be noted that the accompanying figures are intended to present illustrations of exemplary embodiments of the present disclosure. These figures are not intended to limit the scope of the present disclosure. It should also be noted that accompanying figures are not necessarily drawn to scale.

DETAILED DESCRIPTION
[0032] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present technology. It will be apparent, however, to one skilled in the art that the present technology can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form only in order to avoid obscuring the present technology.
[0033] Reference in this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present technology. The appearance of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but no other embodiments.
[0034] 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.

[0035] FIG. 1 illustrates a general overview 100 of a conventional solid quartz ingot having elongated slots around a cylindrical region body running longitudinally along a length and having a flat surface at both ends of the solid quartz ingot. FIG. 2 illustrates general overview of a glass preform assembly 200 to manufacture an optical fibre, in accordance with various embodiments of the present disclosure. FIG. 3 illustrates a close view of a solid quartz protruded ingot 214 of the glass preform assembly 200 in accordance with an embodiment of the present disclosure. FIG. 4 illustrates a flow chart 300 depicting a method of stretching and collapsing performed in a Rod -In-Cylinder process in the glass perform assembly 200, in accordance with various embodiments of the present disclosure.
[0036] The glass preform assembly 200 as shown in FIG. 2 includes a solid glass core rod 206, a hollow glass over-clad tube 204, a hollow glass cylinder 208, a top handle assembly 210 and a bottom handle 220. The top handle 210 assembly includes a top handle 212, a holding tube 222 and a solid quartz protruded ingot 214. The solid glass core rod 206, hollow glass cylinder 208 and the hollow glass over-clad tube 204 (hereinafter, hollow glass tube) are of cylindrical shape. In addition, the hollow glass cylinder 208 is concentric to the hollow glass tube 204 and to the solid glass core rod 206. In an embodiment of the present disclosure, the hollow glass tube 204 is an over-clad tube which is fluorine doped (f-doped tube). The hollow glass tube 204 may be doped with any suitable material. The hollow glass cylinder 208 has a chamfer region with inner tapered structure. In general, chamfer region is a transitional edge between two faces of an object. The chamfer region provides easy insertion of the solid core rod 206 and the hollow glass tube 204 inside the hollow glass cylinder 208 and prevents diameter of the hollow glass cylinder 208 from collapsing during heating in a Rod-In-Cylinder process. Further, handle joining takes place in the glass preform assembly 200. The Rod-In-Cylinder process stretches the hollow glass cylinder 208 and maintains a constant stretch ratio. Stretch ratio is a ratio of initial length of the core to the final length of stretched core. In general, Rod-In-Cylinder process is a large volume

production process for the manufacturing of optical fibre. In rod in cylinder process, vacuum is applied to the void between inner diameter of hollow cylinder and the core rod. The preform assembly is then locally heated to a point where hollow cylinder collapses onto the core rod. The heat source traverses along length of the preform assembly, until the hollow cylinder is fully collapsed. The produced preform is then inspected and prepared for drawing of an optical fibre.
[0037] The top handle assembly 210 includes the top handle 212, the holding tube 222 and the solid quartz protruded ingot 214. The top handle 212 is situated at one of the end of the hollow glass cylinder 208 of the glass preform assembly 200. The solid quartz protruded ingot 214 has a solid cylindrical region 216 and a protruded region 218. The solid cylindrical region 216 of the solid quartz protruded ingot 214 has diameter greater than diameter of the protruded region 218 of the solid quartz protruded ingot 214. The solid cylindrical region 216 of the solid quartz protruded ingot 214 and the protruded region 218 of the solid quartz 214 are connected with each other such that the protruded region 218 forms a composite part of cylindrical region and forms the solid quartz protruded ingot 214. Further, the protruded region 218 has a neck length that fits into the tapered chamfer region of the hollow glass cylinder 208. The protrusion on solid quartz protruded ingot is formed with the help of machining used for cutting glass.
[0038] In an embodiment of the present disclosure, the protruded region 218 of the solid quartz protruded ingot 214 has a length of about 15 +/- 5 millimetres. In an example, if length of the solid quartz protruded ingot 214 is beyond 15 +/- 5 mm, a cavity is formed due to extra elongation. In another example, is length of the solid quartz protruded ingot 214 is below 15 +/- 5 mm, the chamfering cavity is not filled properly that may result in non-uniform profile of core and clad. In an embodiment of the present disclosure, the protruded region 218 of the solid quartz protruded ingot 214 has an outer diameter that is determined by a formula: (Cylinder ID - 3 mm ) ± 2mm. In an

embodiment of the present disclosure, the solid cylindrical region 216 of the solid quartz protruded ingot 214 has a length in range of about 135 ± 20 millimetres. In an example, if the length of the solid cylindrical region 216 is below 135 ± 20 millimetres, the holding tube 222 is collapsed with the hollow glass cylinder 208 and may not be removed from the hollow glass cylinder 208. In another example, if the length of the solid cylindrical region 216 is beyond 135 ± 20 millimetres, the top handle 212 is collapsed with the hollow glass cylinder 208. In general, it is necessary that neither top handle nor holding tube gets collapsed with the hollow glass cylinder as top handle is reusable for the next glass preform assembly in the rod-in-cylinder process and if holding tube is collapsed with the hollow glass cylinder then it will be difficult to extract out the top handle that is reusable. In an embodiment of the present disclosure, the solid cylindrical region 216 of the solid quartz protruded ingot 214 has an outer diameter less than or equal to 78 millimetres. In an example, if the outer diameter of the solid cylindrical region 216 is beyond 78 millimetres, the solid quartz protruded ingot 214 may not fit inside the top handle 212 and below this value chamfering cavity will not be filled up thus leading to gap and will eventually lead to macro-bend losses along the length of the cylinder. In an embodiment of the present disclosure, the solid quartz protruded ingot (214) has total length of about 150 ± 20 millimetres. In an example, if the total length of the solid quartz protruded ingot 214 is below the mentioned range, the holding tube 222 is collapsed with the hollow glass cylinder 208 and may be removed from the hollow glass cylinder 208. In another example, if the total length of the solid quartz protruded ingot 214 is beyond the mentioned range, the top handle 212 is collapsed with the hollow glass cylinder 208. In general, it is necessary that neither top handle nor holding tube gets collapsed with the hollow glass cylinder as top handle is reusable for the next glass preform assembly in rod-in-cylinder process.
[0039] The solid quartz protruded ingot 214 has one or more elongated slot regions 224 on surface of the solid quartz protruded ingot 214 running longitudinally along its length (as shown in FIG. 3). The one or more

elongated slot regions 224 are defined by at least one of 4 slots running across the total length of the solid quartz protruded ingot 214. The one or more elongated slot regions 224 are spaced 90 degree apart. In an embodiment of the present disclosure, the one or more elongated slot regions 224 runs longitudinally along the length of the solid quartz protruded ingot 214. The solid quartz protruded ingot 214 maintains ratio of diameters of core and clad of an optical fibre during the Rod-In-Cylinder process. In an example, the hollow glass cylinder 208 has a diameter of 200 metre that reduces to 150 metre in an optical fibre after stretching. In addition, stretch ratio of the hollow glass cylinder 208 having 150 metre diameter in an optical fibre is in the range of about 1.7-1.8. The stretch ratio provides uniform stretching of the solid glass core rod 206. The stretch ratio maintains initial length of core rod to the final length of the stretched core rod. The solid quartz protruded ingot 214 is a part of the top handle assembly 210 of the glass preform assembly 200 that is employed for manufacturing of the optical fibre with reduced macro-bend loss along the length of cylinder.
[0040] The holding tube 222 resides over the flat surface of the solid quartz protruded ingot 214. The solid quartz protruded ingot 214 is not fixed in the top handle 212. The solid quartz protruded ingot 214 stays in place due to the holding tube 222 above the flat surface of the solid quartz protruded ingot 214. The protruded region 218 of the solid quartz protruded ingot 214 fits around the chamfer region present inside the hollow glass cylinder 208 that inhibits movement of core rod towards the chamfer region. In an embodiment of the present disclosure, shape of the solid quartz protruded ingot 214 and weight of the holding tube 222 balances the vacuum pressure during the Rod-In-Cylinder process. In an example, during stretching of the glass preform assembly 200 in the Rod-In-Cylinder process, there is suction at the top end of top handle assembly 210 of glass preform assembly 200 which acts as a negative vacuum.
[0041] In addition, there is a presence of gap or cavity in the conventional art between the solid quartz ingot and core rod as shown in FIG. 1 due to the

presence of tapered chamfer region. The gap may lead to shifting of the solid core rod out of the hollow glass cylinder because of the application vacuum suction and suction force at the top handle of the glass preform assembly. The solid quartz protruded ingot 214 is designed as per shape of the gap formed around chamfer region in the hollow glass cylinder 208 in the conventional art in between the solid quartz ingot 214 and core rod. In addition, the solid quartz protruded ingot 214 prevents over-stretching of the solid glass core rod 206 and also ensures inhibition of movement of the solid glass core rod 206 and thus helps in maintaining core-clad ratio along the length of cylinder. The solid quartz protruded ingot 214 ensures maintaining uniformity in stretching ratio along the length of hollow glass cylinder 208 that is equal to the initial length of the core rod to the final length of stretched core rod. In an embodiment of the present disclosure, the solid quartz protruded ingot 214 has collar structure that is the protruded region 218. In an embodiment of the present disclosure, length of the protruded region 218 is of same measurement as that of the gap or cavity formed around the chamfer region in the hollow glass cylinder 208. The protruded region 218 of the solid quartz protruded ingot 214 is placed around the gap of 15 millimeters around the chamfer region in between the solid glass core rod 206 and the solid quartz protruded ingot 214. The placement is done to inhibit or restrict the shifting of the solid glass core rod 206 and the hollow glass tube 204 in upward direction from the bottom of the hollow glass cylinder 208.
[0042] In addition, macro-bend loss fibre failure and other waveguide failure is reduced during drawing of the optical fibre due to inhibition of shifting of the solid glass core rod 204. In general, macro-bend loss or macro-bending is defined as loss in optical fiber in form of attenuation and is associated with bending or wrapping of fiber due to which there is a leak out of light and as the bend becomes more acute more light leaks out. This is due to the energy in the evanescent field at the bend exceeding the velocity of light in the cladding and hence the guidance mechanism is inhibited, which causes light energy to be radiated from the fiber.

[0043] The glass preform assembly 200 undergoes pre-heating. In an embodiment of the present disclosure, the pre-heating of the glass preform assembly 200 is done at a temperature range of about 800-1900 degree Celsius to melt preform. At the temperature range of below 800-1900 degree Celsius, ramp up process is done. In an example, it the temperature range is above 1900 C, the bottom handle may result in crack and diameter variation. In another embodiment of the present disclosure, the temperature range at which the glass preform (200) is preheated may vary.
[0044] FIG. 4 illustrates a flow chart 400 depicting a method of stretching and collapsing performed in the Rod -In-Cylinder process in the glass perform assembly 200, in accordance with various embodiments of the present disclosure. It may be noted that in order to explain the method steps of the flowchart 400, references will be made to the elements explained in FIG. 2 and FIG. 3
[0045] The flow chart 400 initiates at step 402. Following at 402, at step 404, the method includes cleaning of the solid glass core rod 206, the hollow glass tube 204, and the hollow glass cylinder 208. In addition, the cleaning of the solid glass core rod 206, the hollow glass tube 204, and the hollow glass cylinder 208 is done using one or more processes. The one or more processes include but may not be limited to HF etching and nitrogen gas (N2) purging. In general, HF etching is a form of wet etching that uses hydrofluoric acid to etch out surfaces. In addition, HF etching is capable of etching materials such as amorphous silicon dioxide and quartz and glass at very high etch rates. In general, nitrogen purging is a method of removing the moisture/water vapor and oxygen to create a dry environment within equipment or a system. In addition, nitrogen purging is an industrial process where unwanted gases and other impurities are eliminated from a manufacturing system environment using nitrogen gas. At step 406, the method includes arranging the solid core rod 206, the hollow glass tube 204, and the hollow glass cylinder 208

concentrically to form the glass preform assembly 200. The solid glass core rod 206 and the hollow glass tube 204 are inserted into the hollow glass cylinder 208. At step 408, the method includes suspension of the glass preform assembly 200 at the top end using the top handle 210 with the help of chuck and joining bottom handle at other end of the glass preform assembly. Prior to stretching and collapsing of the glass preform assembly 200, the glass preform assembly 200 undergoes preheating at temperature range of 800-1900 degree Celsius for initiating melting of the glass preform assembly.
[0046] At step 410, the method includes stretching and collapsing simultaneously of the glass preform assembly 200. In an embodiment of the present disclosure, the stretching is performed at a temperature range of about 1900 to 2100 degrees Celsius. In addition, the stretching is performed by applying force at the top handle 212 of the top handle assembly 210. Further, the collapsing of the glass preform assembly 200 is performed by applying vacuum suction at the top handle 212 through the one or more elongated slot regions 224 on the protruded region 218 and the solid cylindrical region 216 of the solid quartz protruded ingot 214. The elongated slot regions in the solid quartz protruded ingot 214 runs longitudinally along its length. In an embodiment of the present disclosure, the vacuum suction is applied in range of about 930 to 960 milli-bars. In an example, if range of the vacuum suction is below the mentioned range, particle impurities are not removed due to lack in collapsing. In another example, if range of the vacuum suction is beyond the mentioned range, excessive power is required to provide suction. The solid cylindrical region 216 of the solid quartz protruded ingot 214 has diameter greater than diameter of the protruded region 218 of the solid quartz protruded ingot 214. The cylindrical region of solid quartz protruded ingot 216 and protruded region of solid quartz protruded ingot 218 has the one or more elongated slot regions 224.
[0047] The protruded region 218 of the solid quartz protruded ingot 214 fits around the chamfer region in the hollow glass cylinder 208 in between the solid

glass core rod 206 and the solid quartz protruded ingot 214. The protruded region 218 inhibits or controls movement of the solid glass core rod 206 by perfectly fitting around the chamfer region present in the hollow glass cylinder 208. The inhibition movement of the solid glass core rod 206 prevents the solid glass core rod 206 to move from the bottom of the hollow glass cylinder 208 towards the chamfer region and reduces macro-bend losses. Further, it ensures maintaining core-clad ratio along the length of cylinder to maintain the quality of drawn fibre and also ensure maintaining of a uniform stretch ratio along the length of cylinder which is equal to initial length of core rod to the final length of the stretched core rod. Due to maintaining uniform stretching and maintaining core is to clad diameter macro-bend loss and other waveguide failure has been improved. In an embodiment of the present disclosure, the macro-bend losses are less than O.ldB/turn at a wavelength of about 1625 for 30 millimetres radius of the optical fibre. In another embodiment of the present disclosure, value of macro-bend losses may vary depending upon variation in the wavelength and radius of bend in the optical fibre. At step 412, the method includes obtaining a glass preform that is ready to draw for manufacturing the optical fibre.
[0048] The flowchart 400 terminates at step 414. It may be noted that the flowchart 400) is explained to have above stated process steps; however, those skilled in the art would appreciate that the flowchart 400 may have more/less number of process steps which may enable all the above stated embodiments of the present disclosure.
[0049] The result of the above-mentioned process with the help of a protrusion on one the end of solid quartz protruded ingot is reduction in macro-bend loss. The cause of macro-bend loss in an optical fiber is non-uniform stretching along the length of cylinder which disrupts core is to clad diameter and also initial length of the core rod to the final length of the stretched core rod due to which there is a leakage of light from the fiber whenever there is a curve causing fiber to get bent. Due to this bending in the fiber the light is not able

to restrict to core causing loss in total internal reflection in the fiber which helps in the transmission of signals. The solid quartz protruded ingot having protrusion at one of its end ensures maintaining stretching ratio which is ratio of initial length core rod to the final length pf stretched core rod and further maintains ratio of core-clad diameter due to which further lights is restricting in the core causing total internal reflection in the fibre for signal to transmit from one end to another end. Due to improvement in maintaining uniform stretching ratio and core-clad ratio along the length of cylinder there is an improvement in optical fiber waveguide parameter. This process of rod in cylinder is used for ITU G657 series fiber which is employed for FTTH purposes and hence it is required that there should be reduction in macro-bend loss and other waveguide failure as there are bending around corners in the home where optical fiber is used.
[0050] 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.
[0051] While several possible embodiments 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 embodiment should not be limited by any of the above-described exemplary embodiments.

CLAIMS
We claim:

1. A glass preform assembly (200) for manufacturing an optical fibre, the glass
preform assembly (200) comprising:
a solid glass core rod (206), wherein the solid glass core rod has a cylindrical shape;
a hollow glass over-clad tube (204), wherein the hollow glass over-clad tube (204) is concentric to the solid glass core rod (206);
a hollow glass cylinder (208), wherein the hollow glass cylinder (208) is concentric to the hollow glass tube (204) and to the solid glass core rod (206); and
a top handle assembly (210) comprising:
a top handle (212), wherein the top handle (212) is situated at top end of the glass preform assembly (200); and
a solid quartz protruded ingot (214) having a solid cylindrical region (216) and a protruded region (218), wherein the protruded region (218) is at least on one end of the solid quartz protruded ingot (214), wherein the solid quartz protruded ingot (214) has one or more elongated slot regions (224) on surface of the solid quartz protruded ingot (214).
2. The glass preform assembly (200) as claimed in claim 1, wherein the solid
cylindrical region (216) of the solid quartz protruded ingot (214) has diameter

greater than diameter of the protruded region (218) of the solid quartz protruded ingot (214).
3. The glass preform assembly (200) as claimed in claim 1, wherein the solid cylindrical region (216) of the solid quartz protruded ingot (214) and the protruded region (218) of the solid quartz protruded ingot (214) are concentric to each other.
4. The glass preform assembly (200) as claimed in claim 1, wherein the protruded region (218) has a neck length that fits into a chamfer region of the hollow glass cylinder (208).
5. The glass preform assembly (200) as claimed in claim 1, wherein the protruded region (218) of the solid quartz protruded ingot (214) has a length of about 15 millimetres.
6. The glass preform assembly (200) as claimed in claim 1, wherein the protruded region (218) of the solid quartz protruded ingot (214) has an outer diameter which is determined by: (Cylinder ID - 3 mm) ± 2mm. .
7. The glass preform assembly (200) as claimed in claim 1, wherein the solid cylindrical region (216) of the solid quartz protruded ingot (214) has a length in range of about 135 ± 20 millimetres.
8. The glass preform assembly (200) as claimed in claim 1, wherein the solid cylindrical region (216) of the solid quartz protruded ingot (214) has an outer diameter of less than or equal to 78 millimetres.
9. The glass preform assembly (200) as claimed in claim 1, wherein the solid quartz protruded ingot (214) has total length of about 150 ± 20 millimetres.

The glass preform assembly (200) as claimed in claim 1, wherein the one or more elongated slot regions (224) are defined by at least one of 4 slots running across total length of the solid quartz protruded ingot (214), wherein the one or more elongated slot regions (224) are spaced 90 degree apart, wherein the one or more elongated slot regions (224) run longitudinally in the solid quartz protruded ingot (214).
The glass preform assembly (200) as claimed in claim 1, wherein the solid quartz protruded ingot (224) maintains ratio of diameters of core and clad of an optical fibre during a Rod-In-Cylinder process.
A method of stretching and collapsing for manufacturing of an optical fibre using a Rod-In-Cylinder process, the method comprising:
cleaning a solid glass core rod (206), a hollow glass tube (204) and a hollow glass cylinder (208), wherein the cleaning of the solid glass core rod (206), the hollow glass tube (204) and the hollow glass cylinder (208) is done using one or more processes;
arranging the solid glass core rod (206), the hollow glass tube (204) and the hollow glass cylinder (208) concentrically to form a glass preform assembly (200), wherein the solid glass core rod (206) and the hollow glass tube (204) are inserted into the hollow glass cylinder (208);
suspending the glass preform assembly (200) at top end using a top handle assembly (210);
stretching and collapsing the glass preform assembly (200), wherein the stretching is performed at a temperature range of about 1900 to 2100 degrees Celsius, wherein the stretching is performed by applying torque at a top handle (212) of the top handle assembly (210), wherein the collapsing is performed by applying vacuum suction at the top handle (212) through one or more elongated

slot regions (224) on an protruded region (218) and a solid cylindrical region (216) of a solid quartz protruded ingot (214), wherein the solid cylindrical region (216) of the solid quartz protruded ingot (214) has a diameter greater than a diameter of the protruded region (218) of the solid quartz protruded ingot (214), wherein the solid quartz protruded ingot (214) has the one or more elongated slot regions (224) on surface of the solid quartz protruded ingot (214) running longitudinally; and
obtaining a glass preform, wherein the glass preform is ready for drawing for manufacturing the optical fibre.
The method as claimed in claim 12, wherein the one or more processes comprise HF etching and nitrogen gas purging.
The method as claimed in claim 12, wherein the hollow glass cylinder (208) has a chamfer region, wherein the chamfer region prevents diameter of the hollow glass cylinder (208) from collapsing during heating in the Rod-In-Cylinder process.
The method as claimed in claim 12, wherein the elongated neck region (218) of the solid quartz protruded ingot (214) fits around a chamfer region in the hollow glass cylinder (208) in between the solid glass core rod (206) and the solid quartz protruded ingot (214), wherein the protruded region ((218) inhibits or controls movement of the solid glass core rod (204), wherein the inhibition movement of the solid glass core rod (206) prevents the solid glass core rod (206) to move from a bottom handle (220) of the hollow glass cylinder (208) towards the chamfer region and reduces macro-bend losses.
The method as claimed in claim 12, wherein the Rod-In-Cylinder process stretches the hollow glass cylinder (208) and maintains constant stretch ratio.

17. The method as claimed in claim 12, wherein the solid quartz protruded ingot (214) has total length of about 150 ± 20 millimetres.