TECHNICAL FIELD
The present disclosure relates to the field of optical fibre, in particular, the present disclosure relates to an ultra-low loss optical fibre. The present application is based on, and claims priority from an Indian Application Number 201911003617 filed on 29th January 2019, the disclosure of which is hereby incorporated by reference herein.

BACKGROUND
Optical fibre communication has revolutionized the telecommunication industry in the past few years. The use of optical fibre cables has supported to bridge the gap between the distant places around the world. One of the basic components of the optical fibre cable is an optical fibre. The optical fibre is responsible for carrying vast amount of information from one place to another. There are different methods for manufacturing glass bodies and optical fibres. These methods are primarily adopted to manufacture glass preform or glass preform. Few such methods employed for manufacturing optical fibres are powder-in-tube technique, rod-in-cylinder technique, vapor deposition techniques and the like. However, the currently available optical fibres have high attenuation losses.

In the light of the above stated discussion, there is a need for an optical fibre with extremely low attenuation loss.

OBJECT OF THE DISCLOSURE
A primary object of the present disclosure is to provide an optical fibre with an ultra-low losses.

Another object of the present disclosure is to provide the optical fibre with low attenuation.

Yet another object of the present disclosure is to provide the optical fibre having transmitting ability in infrared region.

SUMMARY
In an aspect, the present disclosure provides an optical fibre. The optical fibre includes a core region and a cladding region. The core region is defined along a central longitudinal axis of the optical fibre. In addition, the core region of the optical fibre has a first radius r1 and a first refractive index n1. Further, the cladding concentrically surrounds the core region of the optical fibre. Furthermore, the cladding region of the optical fibre has a second radius r2 and a second refractive index n2. Also, the optical fibre is an ultra-low loss optical fibre. Also, the optical fibre has a step index profile. Also, the step index profile corresponds to sudden change in a value of refractive index.

In an embodiment of the present disclosure, the core region of the optical fibre is made of calcium aluminum silicate.

In an embodiment of the present disclosure, the cladding region of the optical fibre is made of fluorine doped silica.

In an embodiment of the present disclosure, wherein the core region of the optical fibre has the first radius r1 of about 38.35 microns.

In an embodiment of the present disclosure, the cladding region (104) of the optical fibre (100) has the second radius r2 of about 62.5 microns.

In an embodiment of the present disclosure, the outer diameter of the optical fibre (100) with 5 microns. (Not shown in figure)
In an embodiment of the present disclosure, the core region (102) of the optical fibre (100) has the first refractive index n1 of about 1.625.

In an embodiment of the present disclosure, the core region (102) of the optical fibre (100) has the second refractive index n2 of about 1.44.

In an embodiment of the present disclosure, the optical fibre (100) has low attenuation. In addition, the optical fibre (100) has attenuation up to 0.1 decibel/kilometer.

STATEMENT OF THE DISCLOSURE
The present disclosure provides an optical fibre. The optical fibre includes a core region and a cladding region. The core region is defined along a central longitudinal axis of the optical fibre. In addition, the core region of the optical fibre has a first radius r1 and a first refractive index n1. Further, the cladding concentrically surrounds the core region of the optical fibre. Furthermore, the cladding region of the optical fibre has a second radius r2 and a second refractive index n2. Also, the optical fibre has a step index profile. Also, the step index profile corresponds to sudden change in a value of refractive index.

BRIEF DESCRIPTION OF FIGURES
Having thus described the disclosure in general terms, reference will now be made to the accompanying figures, wherein:

FIG. 1 illustrates a cross-sectional view of an optical fibre, in accordance with various embodiments of the present disclosure; and

FIG. 2 illustrates a refractive index profile of the optical fibre, in accordance with various embodiments of the present disclosure;

It should be noted that the accompanying figures are intended to present illustrations of few 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
Reference will now be made in detail to selected embodiments of the present disclosure in conjunction with accompanying figures. The embodiments described herein are not intended to limit the scope of the disclosure, and the present disclosure should not be construed as limited to the embodiments described. This disclosure may be embodied in different forms without departing from the scope and spirit of the disclosure. It should be understood that the accompanying figures are intended and provided to illustrate embodiments of the disclosure described below and are not necessarily drawn to scale. In the drawings, like numbers refer to like elements throughout, and thicknesses and dimensions of some components may be exaggerated for providing better clarity and ease of understanding.

It should be noted that the terms "first", "second", and the like, herein do not denote any order, ranking, quantity, or importance, but rather are used to distinguish one element from another. Further, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

FIG. 1 illustrates a cross-sectional view of an optical fibre 100, in accordance with various embodiments of the present disclosure. In general, optical fibre is used for transmitting information in the form of light pulses from one end to another. In addition, optical fibre is a thin strand of glass or plastic capable of transmitting optical signals. Further, optical fibre is configured to transmit large amount of information over long distances. The optical fibre 100 is optical fibre with ultra-low losses. In an embodiment of the present disclosure, the optical fibre 100 is an ultra-low loss optical fibre. Further, the optical fibre 100 includes a core region 102 and a cladding region 104.

The core region 102 is an inner part of the optical fibre 100. The core region 102 is defined along a central longitudinal axis 106. The central longitudinal axis 106 is an imaginary axis. In addition, the core region 102 of the optical fibre 100 has a first radius r1 and a first refractive index n1. Further, the core region 102 and the cladding region 104 are made during the manufacturing stage of an optical fibre preform. In general, core has higher refractive index than that of cladding. In addition, refractive index is maintained as per desired level based on concentration of chemicals used for the production of optical fibre preform. In an embodiment of the present disclosure, the core region 102 has greater refractive index than that of the cladding region 104 of the optical fibre 100.

In addition, the optical fibre 100 includes cladding region 104. The cladding region 104 of the optical fibre 100 lies between the first radius r1 and a second radius r2. In addition, the cladding region 104 concentrically surrounds the core region 102 of the optical fibre 100. Further, the cladding region 104 of the optical fibre 100 has the second radius r2 and a second refractive index n2.

In an embodiment of the present disclosure, the optical fibre 100 is a multimode fibre. The optical fibre 100 is manufactured from the optical fibre preform. The optical fibre preform may be manufactured by any conventional optical fibre preform manufacturing methods. Examples of such methods include powder-in-tube technique, rod-in-cylinder technique and the like. The optical fibre preform is made of glass. In general, glass is a non-crystalline amorphous solid, often transparent and has widespread applications. The applications of glass range from practical usage in daily life, technological usage, and decorative usage. In general, most common type of glass is silicate glass made of chemical compound silica.

The optical fibre preform is a large cylindrical body of glass having a core structure and a cladding structure. In addition, the optical fibre preform is a material used for fabrication of an optical fibres. Further, the optical fibres are used for variety of purposes. The variety of purposes includes telecommunications, broadband communications, medical applications, military applications and the like. The optical fibre preform is the optical fibre in a large form.

The core structure of the optical fibre preform is manufactured using a calcium aluminium silicate material. The calcium aluminium silicate material is a white free-flowing powder suited for making the core 102 of the optical fibre 100. In addition, the calcium aluminium silicate material is a multicomponent glass material having superior optical properties. The cladding structure of the optical fibre preform is a fluorine doped silica (hereinafter “F-doped silica”) tube. The F-doped silica tube is a cylindrical shaped tube. In an embodiment of the present disclosure, the F-doped silica tube may have any other suitable shape.

In an embodiment of the present disclosure, the optical fibre preform may be manufactured using the powder-in-tube technology. The calcium aluminium silicate powder is added into hollow space inside the F-doped tube. The powder-in-tube technology involves use of a glass cladding tube and a powdery substance. The powdery substance is used for forming the core 102 of the optical fibre 100 and is inserted inside the glass cladding tube. In addition, the glass tube is sintered at a high temperature to form a glass preform. The powder-in-tube technique is employed for manufacturing the optical fibre preform. In an embodiment of the present disclosure, the optical fibre preform may be manufactured using the rod-in-tube method or RIC method. In general, the RIC method refers to a manufacturing process of a large-sized fibre preform by inserting a core rod assembly into a large cylindrical tube. The cylindrical tube is heated and collapsed onto the core rod assembly.

In an embodiment of the present disclosure, the calcium aluminum silicate material is utilized in a powdery form. In an embodiment of the present disclosure, the calcium aluminum silicate powder of a suitable size may be used. The size range may be selected such that the optical fibre preform can be manufactured. In an embodiment of the present disclosure, the optical fibre preform has a diameter of about 44 millimetres. In another embodiment of the present disclosure, the optical fibre preform may have any suitable diameter as per the requirement. In an embodiment of the present disclosure, the core structure of the optical fibre preform has a diameter of about 27 millimetres. In another embodiment of the present disclosure, the core structure of the optical fibre preform may have any suitable diameter as per the requirement.

Fig. 2 illustrates a refractive index profile 200 of the optical fibre 100, in accordance with various embodiments of the present disclosure. The refractive index profile 200 defines the properties of the core region 102 of the optical fibre 100. The refractive index profile 200 illustrates a relationship between refractive index of the core region 102 and the cladding region 104 with the first radius r1 and the second radius r2. In addition, the refractive index profile 200 illustrates change in refractive index of the optical fibre with an increase in radius. The performance of the optical fibre 100 is monitored by controlling a plurality of parameters associated with the refractive index profile 200. Further, the refractive index profile 200 is determined based on a concentration of dopants and materials used during manufacturing. Furthermore, dispersion and bending losses are controlled by varying the design parameters of the refractive index profile 200.

In addition, the refractive index profile 200 is shown on ordinate axis or y-axis and radius are shown on abscissa or x-axis. The refractive index profile 200 is a step index profile (as shown in FIG. 2). The step index profile corresponds to a profile that has abrupt change in value of the refractive index. In addition, the first refractive index n1 is of the core region 102 and the second refractive index n2 is of the cladding region 104 of the optical fibre. In an embodiment of the present disclosure, n1 corresponds to refractive of the calcium aluminum silicate material and n2 corresponds to refractive index of the F-doped Silica.

In an embodiment of the present disclosure, the first refractive index n1 of the core region 102 of the optical fibre 100 is about 1.625. In another embodiment of the present disclosure, value of the first refractive index of the core region 102 of the optical fibre 100 may vary. In an embodiment of the present disclosure, the second refractive index n2 of the cladding region 104 of the optical fibre 100 is about 1.44. In another embodiment of the present disclosure, value of the second refractive index n2 of the cladding region 104 may vary. In an embodiment of the present disclosure, the first radius r1 of the core region 102 the optical fibre 100 is about 38.35 microns. In another embodiment of the present disclosure, value of the first radius r1 of the core region 102 of the optical fibre 100 may vary. In an embodiment of the present disclosure, the second radius r2 of the cladding region 104 of the optical fibre 100 is about 62.5 microns. In another embodiment of the present disclosure, value of the second radius r2 of the cladding region 104 of the optical fibre 100 may vary. The optical fibre 100 has low attenuation. In an embodiment of the present disclosure, the optical fibre 100 has attenuation up to 0.1 decibel/kilometer. In an embodiment of the present disclosure, the core region 102 of the optical fibre 100 is made of calcium aluminum silicate. In another embodiment of the present disclosure, the core region 102 of the optical fibre 100 may be made of any suitable material. In an embodiment of the present disclosure, the cladding region 104 of the optical fibre 100 is made of fluorine doped silica. In another embodiment of the present disclosure, the cladding region 104 of the optical fibre 100 may be made of any suitable material.

The present disclosure provides numerous advantages over the prior art. The present disclosure provides the optical fibre. In addition, the optical fibre has low attenuation. Further, the optical fibre has transmitting ability in infrared region.

The foregoing descriptions of pre-defined 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.

We claim:
1. An optical fibre (100) comprising:
a core region (102), wherein the core region (102) is defined along a central longitudinal axis (106) of the optical fibre (100), wherein the core region (102) of the optical fibre (100) has a first radius r1 and a first refractive index n1; and
a cladding region (104), wherein the cladding (104) concentrically surrounds the core region (102) of the optical fibre (100), wherein the cladding region (104) of the optical fibre (100) has a second radius r2 and a second refractive index n2,
wherein the optical fibre (100) is an ultra-low loss optical fibre, wherein the optical fibre (100) has a step index profile, wherein the step index profile corresponds to abrupt change in a value of refractive index.

2. The optical fibre (100) as claimed in claim 1, wherein the core region (102) of the optical fibre (100) is made of calcium aluminum silicate.

3. The optical fibre (100) as claimed in claim 1, wherein the cladding region (104) of the optical fibre (100) is made of fluorine doped silica.

4. The optical fibre (100) as claimed in claim 1, wherein the core region (102) has the first radius r1 of about 38.35 microns.

5. The optical fibre (100) as claimed in claim 1, wherein the cladding region (104) of the optical fibre (100) has the second radius r2 of about 62.5 microns.

6. The optical fibre (100) as claimed in claim 1, wherein the core region (102) of the optical fibre (100) has the first refractive index n1 of about 1.625. (1.5 -1.7)

7. The optical fibre (100) as claimed in claim 1, wherein the cladding region (104) of the optical fibre (100) has the second refractive index n2 of about 1.44. (1.42-1.44)

8. The optical fibre (100) as claimed in claim 1, wherein the optical fibre (100) has low attenuation, wherein the optical fibre (100) has attenuation up to 0.1 decibel/kilometer.