Description:TECHNICAL FIELD
The present disclosure relates generally to optical fibers, and more particularly to an optical fiber and an optical fiber cable.
BACKGROUND
Optical fibers are suitable in regional, metro, access, mobile, FTTH and 5G applications where high-density cables and accessories are being manufactured. Increasing adoption of FTTH and 5G architectures has led to wider application of bend-insensitive fibers because they ensure low losses in these high-density networks. Optical fiber having reduced (low) glass diameter and overall diameter are need of the market which enables high density cables with small diameters which allow service providers to maximize the number of fibers that can be installed in existing ducts or to minimize the size or even the need for new ducting and related infrastructure. The low bend loss extends to the longer wavelengths which are required for advanced and future systems.
Prior art reference “EP3657223A1” discloses an optical fiber having a depressed layer between a core and a cladding such that a minimum refractive index of the optical fiber is near the core boundary of the optical fiber which may fail to achieve the required optimum optical parameters. For optical fibers, the refractive index profile is generally classified according to the graphical appearance of the function that associates the refractive index with the radius of the optical fiber. These curves are generally representative of the optical fibers theoretical or set profile. Constraints in the manufacture of the optical fiber, however, may result in a slightly different actual profile.
Conventional optical fibers have huge trench depth which is designed to meet the need of FTTH application where optical fiber is operated at a very critical bend value (for ex. 5 mm or 7.5 mm bend radius).
Thus, there is a need to develop an optical fiber that has reduced manufacturing cost and offers optimized optical parameter while using the optical fiber in network access application.
SUMMARY
In an aspect of the present disclosure, an optical fiber is disclosed. The optical fiber has one or more core region such that the one or more core region is an up doped region. The optical fiber further has a cladding region that surrounds the one or more core region. The cladding region has exactly one down doped region and an undoped region, where the down doped region is a continuous region adjacent to the one or more core region such that a radial position of minimum relative refractive index of the optical fiber is within three micrometres (µm) from an interface between the down doped region and the undoped region. The optical fiber has a mode field diameter in a range of 8.8 µm to 9.6 µm at a wavelength 1310 nanometres (nm). The optical fiber has a cable cut-off of less than or equal to 1260 nm.
In another aspect of the present disclosure, an optical fiber ribbon is disclosed. The optical fiber ribbon has a plurality of optical fibers such that at least one pair of optical fibers are intermittently bonded along a predefined length of the optical fiber of the plurality of optical fibers. The optical fiber disclosed in the present disclosure is used in an optical fiber such that adjacent optical fibers are bonded.
In yet another aspect of the present disclosure, an optical fiber cable is disclosed. The optical fiber cable has a plurality of optical fibers such that each optical fiber of the plurality of optical fibers has a core region, a cladding region, and a plurality of buffer tubes. The core region is an up doped region. The cladding region surrounds the core region. The cladding region has exactly (i) one down doped region and (ii) an undoped region, (ii) the down doped region is a continuous region adjacent to the core region such that a minimum relative refractive index of the optical fiber is near an interface between the down doped region and the undoped region, (iii) a mode field diameter of the optical fiber is in a range of 8.8 micrometres (µm) to 9.6 µm at a wavelength 1310 nanometres (nm), (iv) and a cable cut-off of the optical fiber is less than or equal to 1260 nm. Each buffer tube of the buffer tubes encloses one or more optical fibers of the plurality of optical fibers.

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 representation of an optical fiber.
FIG. 1B illustrates a cross-sectional representation of another optical fiber.
FIG. 1C illustrates a cross-sectional representation of another optical fiber.
FIG. 1D illustrates a cross-sectional representation of another optical fiber.
FIG. 1E illustrates a cross-sectional representation of another optical fiber.
FIG. 2 illustrates a graphical representation of a refractive index profile of the optical fiber 100 of FIG. 1A.
FIG. 3 illustrates a graphical representation of another refractive index profile of the optical fiber of FIG. 1A.
FIG. 4 illustrates an optical fiber ribbon.
FIG. 5 illustrates a cross-sectional view of an optical fiber cable.
DEFINITIONS
The term “optical fiber” as used herein refers to a light guide that provides high-speed data transmission. The optical fiber has one or more glass core regions and a glass cladding region. The light moving through the glass core regions of the optical fiber relies upon the principle of total internal reflection, where the glass core regions have a higher refractive index (n1) than the refractive index (n2) of the glass cladding region of the optical fiber.
The term “core region” as used herein refers to the inner most cylindrical structure present in the centre of the optical fiber, that is configured to guide the light rays inside the optical fiber.
The term “cladding” as used herein refers to one or more layered structure covering the core of an optical fiber from the outside, that is configured to possess a lower refractive index than the refractive index of the core to facilitate total internal reflection of light rays inside the optical fiber. Further, the cladding of the optical fiber may have an inner cladding layer coupled to the outer surface of the core of the optical fiber and one or more intermediate and/or outer cladding layers surrounding the inner cladding.
The term “optical fiber cable” as used herein refers to a cable that encloses a plurality of optical fibers.
The term “intermittently bonded ribbon (IBR)” as used herein are the bundles of the optical fibers such that a pair of optical fibers are intermittently bonded along a predefined length of the optical fiber.
The term “trench” as used herein referred to as a down-doped region with a higher down dopant concentration to decrease the refractive index of the down doped region with respect to pure silica.
The term “refractive index” as used herein is referred to as the measure of change of speed of light from one medium to another and is particularly measured in reference to speed of light in vacuum. More specifically, the refractive index facilitates measurement of bending of light from one medium to another medium.
The term “relative refractive index” as used herein is defined as ?%=100×ni2 -n22ni2, where ni is maximum refractive index in region i of an optical fiber unless otherwise specified, and n is the average refractive index of an undoped region of the optical fiber. As used herein, the values of the relative refractive index are given in units of “%”, unless otherwise specified. In some cases where the refractive index of a region is less than the average refractive index of an undoped region, the relative refractive index percentage is negative, and the region is referred as a trench region.
The term “relative refractive index difference” as used herein is referred to as a measure of the relative difference in refractive index between two optical materials. As used herein, the relative refractive index difference is represented by ? and its values are given in units of “%”, unless otherwise specified. In some cases where the refractive index of a region is less than the average refractive index of an undoped region, the relative refractive index percentage is negative, and the region is referred as a trench region.
The term “reduced diameter optical fiber” as used herein refers to an optical fiber as disclosed in the present disclosure having a diameter range of 60 micrometres (µm) to 125 µm with a tolerance of + 0.7 µm. Such optical fibers have very less peripheral clad thickness. The reduced diameter optical fiber significantly increases the packing density of the optical fiber cables.
The term “un doped” as used herein is referred to as a material that is not intentionally doped, or which is pure silica. However, there are always chances of some diffusion of dopants in the region which is negligible.
The term “core volume” as used herein is defined as a volume acquired by the core with respect to the core radius Rc. The core volume may have a magnitude in micrometers square (µm2) that may be determined by the following equation:
= 0Rc? r rdr

wherein Rc is radius of core.
The term “trench volume” as used herein is defined as a volume acquired by region between the core radius Rc and a trench radius R1. The trench volume may have a magnitude in µm2 that may be determined by the following equation:
= RcR1? r rdr
wherein Rc is radius of core,
R1 is trench radius i.e., radius of the down-doped region.
The term “core peak” as used herein is referred to as the maximum refractive index value of the core of the optical fiber.
The term “sharp peak” as used herein is referred to a sudden dip or sudden rise in the relative refractive index profile.
The term “reduced diameter optical fiber” as used herein is referred to as an optical fiber as disclosed in the present disclosure having a diameter range less than to 125 micrometers (µm) with a tolerance of + 0.7 µm. Such optical fibers have very less peripheral clad thickness. The reduced diameter optical fiber significantly increases the packing density of the optical fiber cables.
The term “refractive index profile” (also termed as relative refractive index profile ?(r)) of the optical fiber as used herein is referred to as a distribution of refractive indexes in the optical fiber from the core to the outmost cladding layer of the optical fiber. Based on the refractive index profile, the optical fiber may be configured as a step index fiber. The refractive index of the core of the optical fiber is constant throughout the fiber and is higher than the refractive index of the cladding. Further, the optical fiber may be configured as a graded index fiber, wherein the refractive index of the core gradually varies as a function of the radial distance from the center of the core.
The term “down doped” as used herein is referred to as addition of doping materials to facilitate decrease in the refractive index of a particular layer or part of optical fiber. The materials configured to facilitate down-doping are known as down-dopants. Specifically, at least one down dopant as used herein is Fluorine.
The term “up doped” as used herein is referred to as addition of doping materials to facilitate increase in the refractive index of a particular layer or part of optical fiber. The materials configured to facilitate up-doping are known as up-dopants. Specifically, the up dopant as used herein is one of Germanium and Chlorine.
The term “Mode Field Diameter (MFD)” as used herein is referred to as the size of the light-carrying portion of the optical fiber. For single-mode optical fibers, this region has the optical fiber core as well as a small portion of the surrounding cladding glass of the optical fiber. The selection of desired MFD helps to describe the size of the light-carrying portion of the optical fiber.
The term “macro bend loss” as used herein is referred to as the losses induced in bends around mandrels (or corners in installations), generally more at the cable level or for fibers. The macro bend loss occurs when the fiber cable is subjected to a significant amount of bending above a critical value of curvature. The macro bend loss is also defined as large radius loss. The macro bend loss is measured as per IEC standards. The optical fiber with lower macro bend loss is required for better performance in optical network, especially during the cable termination.
The term “micro bend loss” as used herein is referred to as a loss in an optical fiber that relates to a light signal loss associated with lateral stresses along a length of the optical fiber. The micro bend loss is due to coupling from the optical fiber’s guided fundamental mode to lossy modes or cladding modes.
The term “Zero Dispersion Wavelength (ZDW)” as used herein is referred to as a wavelength at which the value of a dispersion coefficient is zero. In general, ZDW is the wavelength at which material dispersion and waveguide dispersion cancel one another.
The term “attenuation” as used herein is referred to as reduction in power of a light signal as it is transmitted. Specifically, the attenuation is caused by Rayleigh scattering, absorption of the light signal, and the like. The attenuation in an optical fiber is measured with Optical Time Domain Reflectometer (OTDR) device as per IEC standards. The optical fiber disclosed in the present disclosure has low attenuation which helps in increasing the link length of an optical fiber and/or optical fiber cable.
The term “cable cut-off wavelength” as used herein refers to a wavelength above which a single-mode fiber will support and propagate only one mode of light. The optical fiber transmits a single mode of optical signal above a pre-defined cut-off wavelength known as cable cut-off wavelength measured on 22 meters sample length of the optical fiber.
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 representation of an optical fiber 100. The optical fiber 100 may achieve low bend insensitivity and tighter attenuation which may meet and exceed ITU-T G.652.D and G.657.A1 recommendations. The optical fiber 100 may have a refractive index profile that may be modified in such a way that the optical fiber 100 may become very cost effective and may become an ideal choice for network access application. The optical fiber 100 may be independent of any buffer clad region i.e., the optical fiber 100 is free from any pure silica region adjacent to a core region of the optical fiber 100. The optical fiber 100 may be free from any pure silica region and thereby may reduce manufacturing time, cost and/or process steps while manufacturing the optical fiber 100 and may simultaneously achieve the better MFD and other waveguide parameters. The optical fiber 100 may be used in an access network application. The optical fiber 100 may be further used in a long-haul communication with entire spectrum range 1260-1625 nanometres. The optical fiber 100 may has low attenuation as compared to G652D category optical fiber and may has improved bend sensitivity. The optical fiber 100 may comply with ITU G657A1 standard and may achieve better optical parameters and waveguide parameters.
The optical fiber 100 may have a core region 102and a cladding region 104. The cladding region 104 may have an inner cladding region 104a and an outer cladding region 104b.
The optical fiber 100 may have a mode field diameter that may be in a range of 8.8 micrometers (µm) to 9.6 µm at a wavelength 1310 nanometres (nm). If the mode field diameter of an optical fiber is below 8.8 µm, the optical fiber may not be compatible for long haul application and access network application. If the mode file diameter of an optical fiber is above 9.6 µm, the light confinement in the optical fiber is very poor which induces more bend losses such as macro bend and micro bending losses. The optical fiber 100 may have a cable cut-off value that may be less than or equal to 1260 nm. If the cable cut-off value of an optical fiber is above 1260 nm, the optical fiber may not be compatible with typical telecommunication application and 1280 nm to 1310 nm window may not be used in a single mode operation for telecommunication application of the optical fiber.
In some aspects of the present disclosure, at least one of, (i) an attenuation of the optical fiber 100 at 1310 nm wavelength may be less than or equal to 0.33 Decibel (dB), (ii) an attenuation of the optical fiber 100 at 1383 nm wavelength may be less than or equal to 0.31 dB, (iii) an attenuation of the optical fiber 100 at 1550 nm wavelength may be less than or equal to 0.19 dB, and (iv) an attenuation of the optical fiber 100 at 1625 nm wavelength may be less than or equal to 0.21 dB.
In some aspects of the present disclosure, at least one of, (i) a macro bend loss of the optical fiber 100 at 10 millimeters (mm) bend radius and 1625 nm wavelength may be less than or equal to 1.5 dB per unit turn i.e., 1.5 dB/turn and (ii) a macro bend loss of the optical fiber 100 at 15 mm bend radius and 1625 nm wavelength may be less than or equal to 0.3 dB per unit turn i.e., 0.3 dB/turn.
In some aspects of the present disclosure, the optical fiber 100 may have a zero-dispersion wavelength (ZDW) value that may be in a range of 1300 nm to 1324 nm.
The core region 102 may be disposed at a center of the optical fiber 100. The core region 102 may be an up doped region 208, 308 (as shown later in FIG. 2 and FIG. 3). In other words, the core region 102 may be a region with high relative refractive index region. Specifically, the core region 102 may be up-doped with a plurality of up-dopant materials (hereinafter referred to as “the up-dopant materials”). The up-dopant materials may be, but not limited to, chlorine, Germanium (Ge), aromatic group material, sulfur atoms, halogens, and phosphorous based group materials. Aspects of the present disclosure are intended to include and/or otherwise cover any type of known and later developed up-dopant materials, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, the core region 102 may have (i) a core volume that may be in a range of 4.5 µm2 to 5.5 µm2, (ii) a core relative refractive index that may be in a range of 0.37 % to 0.44 %, and (iii) a core alpha value that may be in a range of 3 to 6. If the core volume of an optical fiber is more, the cable cut-off of the optical fiber will be greater than 1260 nm, and the optical fiber will not show the property of single mode fiber and if core volume of the optical fiber is less, the light confinement in the optical fiber is poor as mode field diameter will be greater than 9.6 µm which subsequently increase the bend losses.
The cladding region 104 may be positioned adjacent to the core region 102. The cladding region 104 may be positioned adjacent to the core region 102 such that the cladding region 104 surrounds the core region 102. The inner cladding region 104a may be positioned adjacent to the core region 102. Specifically, the inner cladding region 104a may be positioned adjacent to the core region 102 such that the inner cladding region 104a surrounds the core region 102. The outer cladding region 104b may be positioned adjacent to the inner cladding region 104a. Specifically, the outer cladding region 104b may be positioned adjacent to the outer cladding region 104b such that the outer cladding region 104b surrounds the inner cladding region 104a. The cladding region 104 may have exactly (a) one down doped region 210, 310 (as shown later in FIG. 2 and FIG. 3) and (b) an undoped region 212, 312 (as shown later in FIG. 2 and FIG. 3). Specifically, the inner cladding region 104a may have the one down doped region 210, 310 and the outer cladding region 104b may have the undoped region 212, 312. The down doped region 210, 310 may be a continuous region that may be adjacent to the core region 102 such that a minimum relative refractive index 214, 314 of the optical fiber 100 may be near to an interface between the down doped region 210, 310 and the undoped region 212, 312. An inner boundary and an outer boundary of the down doped region 210, 310 may be identified by radial interfaces in the optical fiber 100. In some aspects of the present disclosure, the continuous region may be defined as there may be no buffer region (un doped region) between the core region 102 and the down doped region 210, 310. If there is a buffer region adjacent to the core region 102, the mode field diameter of the optical fiber 100 may increase beyond 9.6 µm which may impact the confinement of light in the core region 102 and subsequently increases the macro bend loss of the optical fiber 100. In some other aspects of the present disclosure, a radial position of the minimum relative refractive index 214, 314 of the optical fiber 100 may be within three µm from the interface between the down doped region 210, 310 and the undoped region 212, 312. The radial position of the minimum relative refractive index 214, 314 of the optical fiber 100 may help to achieve optimized mode field diameter as required in the optical fiber 100 of the present disclosure. If the radial position of the minimum relative refractive index 214, 314 of the optical fiber 100 is not designed properly, this will lead to very low mode field diameter.
In some aspects of the present disclosure, the interface between the down doped region 210, 310 and the undoped region 212, 312 may lie at a radial distance of 12 µm to 20 µm from a center of the optical fiber 100.
In some aspects of the present disclosure, the down doped region 210, 310 may have a trench alpha that may be in a range of 1 to 3. The down doped region 210, 310 may further have a trench volume that may be in a range of 3 µm2 to 4.5 µm2. If the trench volume of an optical fiber is very less, this may lead to significant rise in bend losses of the optical fiber and if the trench volume is very high, the cable cut-off value of the optical fiber may increase beyond 1260 nm and mode field diameter may decrease below 8.8 µm.
In some aspects of the present disclosure, the down doped region 210, 310 may have a thickness that may be in a range of 8 µm to 12 µm.
In some aspects of the present disclosure, the core region 102 and the cladding region 104 may be made up of a material including, but not limited to, glass. The core region 102 and the cladding region 104 may have a diameter i.e., a glass diameter of the optical fiber 100 that may be less than or equal to 125 µm with a tolerance value of + 0.7 µm i.e., 125 + 0.7 µm. Aspects of the present disclosure are intended to include and/or otherwise cover any type of known and later developed materials for the core region 102 and the cladding region 104.
In some aspects of the present disclosure, the core region 102 and the cladding region 104 may have a diameter i.e., a glass diameter of the optical fiber 100 may be less than or equal to 125 µm with a tolerance value of + 0.7 µm i.e., 125 + 0.7 µm.
In some aspects of the present disclosure, the core region 102 may have a radius Rc (as shown later in FIG. 2 and FIG. 3) that may be in a range of 4 µm to 5.5 µm. The core region 102 may have a relative refractive index ?c (as shown later in FIG. 2 and FIG. 3) that may be in a range of 0.37% to 0.44%. The core region 102 may have a core volume that may be in a range of 4.5 µm2 to 5.5 µm2. The core region 102 may have a core alpha value ‘ac’ that may be in a range of 3 to 6. The core region 102 may have a relative refractive index difference (N) that may be in a range of 0.0055 to 0.0065. The refractive index difference (N) as used herein may be difference between the refractive index of the core region 102 and refractive index of pure silica. In first example of the present disclosure, the radius Rc of the core region 102 may be 4.43 µm, the relative refractive index ?c of the core region 102 may be 0.4%, the core volume of the core region 102 may be 4.776 µm2, the core alpha value ‘ac’ of the core region 102 may be 3, and the refractive index difference (N) of the core region 102 may be 0.0058. In second example of the present disclosure, the radius Rc of the core region 102 may be 4.5 µm, the relative refractive index ?c of the core region 102 may be 0.38%, the core volume of the core region 102 may be 4.81 µm2, the core alpha value ‘ac’ of the core region 102 may be 3.4, and the relative refractive index difference (N) of the core region 102 may be 0.0056. In third example of the present disclosure, the radius Rc of the core region 102 may be 4.4 µm, the relative refractive index ?c of the core region 102 may be 0.41%, the core volume of the core region 102 may be 4.8 µm2, the core alpha value ‘ac’ of the core region 102 may be 4, and the refractive index difference (N) of the core region 102 may be 0.006. In fourth example of the present disclosure, the radius Rc of the core region 102 may be 5.1 µm, the relative refractive index ?c of the core region 102 may be 0.38%, the core volume of the core region 102 may be 4.75 µm2, the core alpha value ‘ac’ of the core region 102 may be 5, and the relative refractive index difference (N) of the core region 102 may be 0.0049. In fifth example of the present disclosure, the radius Rc of the core regions 102 may be 5.8 µm, the relative refractive index ?c of the core region 102 may be 0.39, the core volume of the core region 102 may be 5.2 µm2, the core alpha value ‘ac’ of the core region 102 may be 4, and the refractive index difference (N) of the core region 102 may be 0.0057.
The relative refractive index profile of the core region 102 may be the alpha profile such that the core refractive index ‘N’ may be derived from the core alpha value ‘ac’ of the peak shaping parameter alpha. In some aspects of the present disclosure, the core alpha value ‘ac’ of the core 102 may be in a range of 3 to 6. The core refractive index ‘N’ may further be dependent on a core peak with a maximum refractive index value ‘Nmax’ (i.e., a maximum value of the core refractive index ‘N’), the core radius ‘Rc’, the core relative refractive index difference ‘?c’, and a radial position ‘r’ from a center of the optical fiber 100. In an exemplary aspect of the present disclosure, the core refractive index ‘N’ at the radial distance ‘r’ can be determined as: Nr=Nmax1-2?c(rRc)ac1/2.
In some aspects of the present disclosure, the down doped region 210, 310 may have a radius R1 (as shown later in FIG. 2 and 3) that may be in a range of 12 µm to 20 µm, the down doped region 210, 310 may have a refractive index difference (N1) that may be in a range of -0.0005 to -0.003. The refractive index difference (N1) as used herein refers to a difference between the refractive index of the cladding region 104 and the refractive index of pure silica. The down doped region 210, 310 may further have a relative refractive index ?1 (as shown later in FIG. 2 and 3) that may be in a range of -0.05% to -0.21%. The down doped region 210, 310 may further have a trench volume that may be in a range of 3 µm2 to 4.5 µm2. In first example of the present disclosure, the R1 may be 15 µm, the relative refractive index difference (N1) may be -0.0025, the relative refractive index ?1 may be -0.17%, and the trench volume may be 3.361 µm2. In second example of the present disclosure, the R1 may be 17 µm, the refractive index difference (N1) may be -0.0027, the relative refractive index ?1 may be -0.18%, and the trench volume may be 3.5 µm2. In third example of the present disclosure, the R1 may be 13 µm, the refractive index difference (N1) may be -0.002, the relative refractive index ?1 may be -0.14%, and the trench volume may be 3.35 µm2. In fourth example of the present disclosure, the R1 may be 16 µm, the refractive index difference (N1) may be -0.0015, the relative refractive index ?1 may be -0.1%, and the trench volume may be 3.3 µm2. In fifth example of the present disclosure, the R1 may be 15 µm, the refractive index difference (N1) may be -0.0006, the relative refractive index ?1 may be 0.05%, and the trench volume may be 3 µm2.
The relative refractive index profile of the down doped region 210, 310 may be the alpha profile such that the refractive index ‘N1’of the down doped region 210, 310 may be derived from the trench alpha value ‘a1’ of the peak shaping parameter alpha. In some aspects of the present disclosure, the trench alpha value ‘a1’ of the down doped region 210, 310 may be in a range of 1 to 3. The refractive index ‘N1’ may further be dependent on a minimum refractive index value ‘N1min’ (i.e., a minimum value of the refractive index ‘N1’ of the down doped region 210, 310), the core radius ‘Rc’, the radius ‘R1’ of the down doped region 210, 310, the relative refractive index difference ‘?1’ of the down doped region 210, 310, and the radial position ‘r’ from a center of the optical fiber 100. In an exemplary aspect of the present disclosure, the refractive index ‘N1’ at the radial distance ‘r’ can be determined as: N1r=N1min1-2?1{r-R1Rc-R1}a11/2.
In some aspects of the present disclosure, the undoped region 212, 312 may have a relative refractive index ?2 (as shown later in FIG. 2 and 3) that may be in a range of -0.01% to 0.01%. The undoped region 212, 312 may further have a radius R2 (as shown later in FIG. 2 and 3) that may be in a range of 62.15 µm to 62.85 µm. In one example of the present disclosure, the relative refractive index ?2 may be 0 and the radius R2 may be 62.5 + 0.35 µm. In other aspects of the present disclosure, the radius R2 may be less than 62.5 µm.
In some aspects of the present disclosure, a mode field diameter (MFD) value of the optical fiber 100, at a wavelength 1310 nm, may be 9.283, 9.02, 9.12, 8.97. In some aspects of the present disclosure, the optical fiber 100 may have a cable cut-off value that may be one of, 1153 nm, 1163 nm, 1220 nm, 1212 nm, and 1214 nm. In some aspects of the present disclosure, the optical fiber 100 may have a zero-dispersion wavelength (ZDW) that may be one of, 1310 nm, 1307 nm, 1309 nm, 1311 nm, and 1310.6 nm.
In some aspects of the present disclosure, a macro bend loss the optical fiber 100 at 20 mm bend radius and 1550 nm wavelength may be one of, 0.414 dB/turn, 0.401 dB/turn, 0.18 dB/turn, 0.186 dB/turn, and 0.231 dB/turn. The macro bend loss of the optical fiber 100 at 20 mm bend radius and 1625 nm wavelength may be one of, 0.935 dB/turn, 1.262 dB/turn, 0.54 dB/turn, 0.544 dB/turn, and 0.69 dB/turn. The macro bend loss of the optical fiber 100 at 30 mm bend radius and 1550 nm wavelength may be one of, 0.111 dB/10 turns, 0.099 dB/10 turns, 0.06 dB/10 turns, 0.31 dB/10 turns, and 0.034 dB/10 turns. The macro bend loss of the optical fiber 100 at 30 mm bend radius and 1625 nm wavelength may be one of, 0.588 dB/10 turns, 0.423 dB/10 turns, 0.1 dB/10 turns, 0.141 dB/10 turns, and 0.128 dB/10 turns.
FIG. 1B illustrates a cross-sectional representation of another optical fiber 101. The optical fiber 101 may be same or substantially similar to the optical fiber 100. However, the optical fiber 101 may have a single-colored coating layer 106. For sake of brevity, same reference numerals have been used for different regions and layers of the optical fiber 101 as being used for different layers/regions of the optical fiber 100. The single-colored coating layer 106 may be positioned adjacent to the cladding region 104. Specifically, the single-colored coating layer 106 may be positioned adjacent to the cladding region 104 such that the single-colored coating layer 106 surrounds the cladding region 104.
In some aspects of the present disclosure, the single-coloured coating layer 106 may have a diameter i.e., a coating diameter of the optical fiber 100 that may be less than or equal to 250 µm with a tolerance value of + 10 µm i.e., 250 + 10 µm.
In some aspects of the present disclosure, the single-coloured coating layer 106 may have a thickness that may be less than 65 µm.
FIG. 1C illustrates a cross-sectional representation of another optical fiber 103. The optical fiber 103 may be same or substantially similar to the optical fiber 100. However, the optical fiber 103 may have a primary coating layer 108 and a colored secondary coating layer 110. For sake of brevity, same reference numerals have been used for different regions and layers of the optical fiber 103 as being used for different layers/regions of the optical fiber 100.
The primary coating layer 108 may be positioned adjacent to the cladding region 104. Specifically, the primary coating layer 108 may be positioned adjacent to the cladding region 104 such that the primary coating layer 108 surrounds the cladding region 104. The colored secondary coating layer 110 may be positioned adjacent to the primary coating layer 108. Specifically, the colored secondary coating layer 110 may be positioned adjacent to the primary coating layer 108 such that the colored secondary coating layer 110 surrounds the primary coating layer 108.
In some aspects of the present disclosure, the optical fiber 103 may have a diameter that may be less than or equal to 180 µm. In some other aspects of the present disclosure, the optical fiber 103 may have the diameter that may be less than or equal to 200 µm. In some other aspects of the present disclosure, the optical fiber 103 may have the diameter that may be less than 250 µm.
FIG. 1D illustrates a cross-sectional representation of another optical fiber 105. The optical fiber 105 may be same or substantially similar to the optical fiber 103. However, the optical fiber 105 may have a secondary coating layer 112, and an ink layer 114, instead of the colored secondary coating layer 110. For sake of brevity, same reference numerals have been used for different regions and layers of the optical fiber 105 as being used for different layers/regions of the optical fiber 103.
The secondary coating layer 112 may be positioned adjacent to the primary coating layer 108. Specifically, the secondary coating layer 112 may be positioned adjacent to the primary coating layer 108 such that the secondary coating layer 112 surrounds the primary coating layer 108.
In some aspects of the present disclosure, the primary coating layer 108 of the optical fiber 103 and 105 may have a young’s modulus that may be in a range of 0.1 Mega-pascal (MPa) to 0.3 MPa. Preferably, the primary coating layer 108 of the optical fiber 103 and 105 may have the young’s modulus that may be less than 0.6 MPa.
In some aspects of the present disclosure, the primary coating layer 108 of the optical fiber 103 and 105 may have a thickness that may be in a range of 10 µm to 30 µm.
In some aspects of the present disclosure, the secondary coating layer 112 of the optical fiber 105 may have a young’s modulus that may be in a range of 1200 MPa to 1500 MPa. Preferably, the secondary coating layer 112 of the optical fiber 105 may have the young’s modulus that may be less than 1500 MPa.
In some aspects of the present disclosure, the secondary coating layer 112 of the optical fiber 105 may have a thickness that may be in a range of 10 µm to 30 µm.
The ink layer 114 may be positioned adjacent to the secondary coating layer 112. The ink layer 114 may be a colored coating layer. Specifically, the ink layer 114 may be positioned adjacent to the secondary coating layer 112 such that the ink layer 114 surrounds the secondary coating layer 112.
In some aspects of the present disclosure, the ink layer 114 may have a thickness that may be in a range of 4 µm to 8 µm.
In some aspects of the present disclosure, the optical fiber 100, 101, 103, and 105 may have a diameter that may be less than or equal to 210 µm.
In some aspects of the present disclosure, the core region 102 may be independent of a sharp peak at a center (R0) of the optical fiber 100, 101, 103, and 105. In other words, the one or more core region 102 of the optical fiber 100, 101, 103, and 105 is free from a sharp peak at a centre of the one or more core region 102.
FIG. 1E illustrates a cross-sectional representation of another optical fiber 107. The optical fiber 107 may be same or substantially similar to the optical fiber 100. However, the optical fiber 107 may have a plurality of core regions 102a-102n (hereinafter referred to and designated as “the core regions 102”), instead of a single core region 102. For sake of brevity, same reference numerals have been used for different regions and layers of the optical fiber 107 as being used for different layers/regions of the optical fiber 100. The core regions 102 may be disposed within the inner cladding region 104a. In other words, the inner cladding region 104a may be positioned adjacent to the core regions 102 such that the inner cladding region 104a surrounds the core regions 102.
FIG. 2 illustrates a graphical representation 200 of a refractive index profile 202 of the optical fiber 100 of FIG. 1A. The graphical representation 200 may be plotted between a radius of the optical fiber 100 along a horizontal axis (X-axis) and a relative refractive index of the optical fiber 100 along vertical axis (Y-axis). The refractive index profile 202 may represent a relative refractive index of the optical fiber 100. The refractive index profile 202 may vary from a center of the core region 102 to a periphery of the cladding region 104. The refractive index profile 202 may have a first refractive index profile 204 and a second refractive index profile 206.
The core region 102 may have a radius Rc. The core region 102 may have a relative refractive index ?c. The core region 102 may have the first refractive index profile 204. In other words, the first refractive index profile 204 may represent a relative refractive index of the core region 102. The first refractive index profile 204 may have the up doped region 208 i.e., the first refractive index profile 204 may be the high relative refractive index region. Specifically, each core region of the core region 102 may be up-doped with the plurality of materials (hereinafter referred to as “the up-dopant materials”). The up-dopant materials may be, but not limited to, chlorine, Germanium (Ge), aromatic group material, sulfur atoms, halogens, and phosphorous based group materials. Aspects of the present disclosure are intended to include and/or otherwise cover any type of known and later developed up-dopant materials, without deviating from the scope of the present disclosure.
The cladding region 104 may have the second refractive index profile 206. In other words, the second refractive index profile 206 may represent a relative refractive index of the cladding region 104. The second refractive index profile 206 may have the down doped region 210 and the undoped region 212. The down doped region 210 may have a radius R1. The down doped region 210 may have a relative refractive index ?1. The down doped region 210 may be a continuous region that may be adjacent to the core region 102 such that radial position of minimum relative refractive index 214, 314 of the optical fiber 100 may be within three µm from the interface between the down doped region 210 and the undoped region 212. The down doped region 210 may be down doped with a predefined amount of fluorine (F). The predefined amount of fluorine may be very low as a depth of the down doped region 210 is very low. The fluorine being lower in the amount may reduce manufacturing time of the optical fiber 100 and may further reduce cost of production associated with the optical fiber 100. The relative refractive index in the down doped region 210 may gradually decrease. Specifically, the relative refractive index in the down doped region 210 may gradually decrease from a boundary of the core region 102 to the interface between the down doped region 210 and the undoped region 212. The undoped region 212 may have a radius R2. The undoped region 212 may have a relative refractive index ?2.
In some aspects of the present disclosure, the down doped region 210 may have a minimum relative refractive index 214, 314 that may be in a range of -0.05 % to -0.21 %.
FIG. 3 illustrates a graphical representation 300 of another refractive index profile 302 of the optical fiber 100 of FIG. 1A. The graphical representation 300 may be plotted between a radius of the optical fiber 100 along a horizontal axis (X-axis) and a relative refractive index of the optical fiber 100 along vertical axis (Y-axis). The refractive index profile 302 may represent a relative refractive index of the optical fiber 100. The refractive index profile 302 may vary from a center of the core region 102 to a periphery of the cladding region 104. The refractive index profile 302 may have a first refractive index profile 304 and a second refractive index profile 306.
The core region 102 may have a radius Rc. The core region 102 may have a relative refractive index ?c. The core region 102 may have the first refractive index profile 304. In other words, the first refractive index profile 304 may represent a relative refractive index of the core region 102. The first refractive index profile 304 may have the up doped region 308 i.e., the first refractive index profile 304 may be the high relative refractive index region. Specifically, each core region of the core region 102 may be up-doped with the plurality of materials (hereinafter referred to as “the up-dopant materials”). The up-dopant materials may be, but not limited to, chlorine, Germanium (Ge), aromatic group material, sulfur atoms, halogens, and phosphorous based group materials. Aspects of the present disclosure are intended to include and/or otherwise cover any type of known and later developed up-dopant materials, without deviating from the scope of the present disclosure.
The cladding region 104 may have the second refractive index profile 306. In other words, the second refractive index profile 306 may represent a relative refractive index of the cladding region 104. The second refractive index profile 306 may have the down doped region 310 and the undoped region 312. The down doped region 310 may have a radius R1. The down doped region 310 may have a relative refractive index ?1. The down doped region 310 may be a continuous region that may be adjacent to the core region 102 such that a radial position of the minimum relative refractive index 214, 314 of the optical fiber 100 may be within three µm from the interface between the down doped region 310 and the undoped region 312. The relative refractive index in the down doped region 310 may decrease. Specifically, the relative refractive index in the down doped region 310 may gradually decrease from a boundary of the core region 102 to a point near to the interface between the down doped region 310 and the undoped region 312 and then rapidly decreases near the interface between the down doped region 310 and the undoped region 312. The undoped region 312 may have a radius R2. The undoped region 312 may have a relative refractive index ?2.
In some aspects of the present disclosure, the down doped region 210 may have a minimum relative refractive index 214, 314 that may be in a range of -0.05 % to -0.21 %.
FIG. 4 illustrates an optical fiber ribbon 400. The optical fiber ribbon 400 may have a plurality of optical fibers 402a-402n (hereinafter collectively referred to and designated as “the fibers 402”). Each fiber of the fibers 402 may be same or substantially similar to the optical fiber 103 of FIG. 1C. Specifically, each fiber of the fibers 402 may be structurally and functionally same or similar to the optical fiber 103 of FIG. 1C. To form the optical fiber ribbon 400, at least one pair of optical fibers of the fibers 402 may be intermittently bonded along a predefined length of the optical fiber of the optical fibers 402. Specifically, the at least one pair of optical fibers of the fibers 402 may be intermittently bonded along a longitudinal axis by a plurality of bonded portions 404a-404n (hereinafter collectively referred to and designated as “the bonded portions 404”). The bonded portions 404 may be adapted to bind the adjacent pair of fibers of the fibers 402.
Each core region of the core region 102 may be the up doped region 208 (as shown in FIG. 2). The cladding region 104 may surround the core region 102. The colored secondary coating layer 110 may define an outer diameter that may be in a range of 160 µm to 210 µm. The cladding region 104 may have exactly (a) the down doped region 210, 310 and the undoped region 312. The down doped region 210, 310 may be a continuous region that may be adjacent to the core region 102 such that the minimum relative refractive index 214, 314 of each optical fiber of the optical fibers 402 may be near to the interface between the down doped region 210, 310 and the undoped region 312. Each optical fiber of the optical fibers 402 may have the mode field diameter that may be in a range of 8.8 µm to 9.6 µm at a wavelength 1310 nm. Each optical fiber of the optical fibers 402 may further have a cable cut-off value that may be less than or equal to 1260 nm. The cladding region 104 may define a bare fiber diameter that may be less than or equal to 125 µm with a tolerance value of 0.7 µm i.e., 125 + 0.7 µm.
FIG. 5 illustrates a cross-sectional view of an optical fiber cable 500. The optical fiber cable 500 may have a central strength member 501 (hereinafter referred to as “the CSM”), a plurality of optical fiber ribbons 502a-502n (hereinafter collectively referred to and designated as “the ribbons 502”), a plurality of buffer tubes 504a-504n (hereinafter collectively referred to and designated as “the buffer tubes 504”), a plurality of water swellable yarns 506a-506n (hereinafter collectively referred to and designated as “the yarns 506”), a plurality of ripcords 508a-508n (hereinafter collectively referred to and designated as “the ripcords 508”), a plurality of multiple strength members 510a-510n (hereinafter collectively referred to and designated as “the strength members 510”), and one or more sheath layers 512a, 512b (hereinafter collectively referred to and designated as “the sheath layers 512”), and one or more binders 514a-514n (hereinafter collectively referred to and designated as “the binders 514”).
The ribbons 502, the buffer tubes 504, the yarns 506, the ripcords 508, the strength members 510, and the CSM 501 may be disposed within the optical fiber cable 500. Specifically, the ribbons 502, the buffer tubes 504, the yarns 506, the ripcords 508, the strength member 510, and the CSM 501 may be disposed within the sheath layers 512.
The CSM 501 may be disposed at a center of the optical fiber cable 500. Specifically, the CSM 501 may be disposed at the center of the optical fiber cable 500 such that the buffer tubes 504 are arranged around the CSM 501. The CSM 501 may be adapted to provide strength to the optical fiber cable 500.
Each ribbon of the ribbons 502 may enclose a plurality of optical fibers 518a-518n (hereinafter collectively referred to and designated as “the optical fibers 518”). In other words, the optical fibers 518 may be disposed within each ribbon of the ribbons 502. Each fiber of fiber 502 may be same or substantially similar to the optical fiber 100 of FIG. 1A. Specifically, each fiber of the fibers 502 may be structurally and functionally same or similar to the optical fiber 100 of FIG. 1A.
Each buffer tube of the buffer tubes 504 may be adapted to enclose the ribbons 502. In other words, the ribbons 502 may be disposed within each buffer tube of the buffer tubes 504. Specifically, each buffer tube of the buffer tubes 504 may be adapted to enclose one or more optical fibers of the plurality of optical fibers. Each buffer tube of the buffer tubes 504 may be arranged around the CSM 501 to form one or more layers.
In some aspects of the present disclosure, each buffer tube of the buffer tubes 504 may be made up of a material, including but not limited to, polybutylene terephthalate (PBT). Aspects of the present disclosure are intended to include and/or otherwise cover any type of material for each buffer tube of the buffer tubes 504, without deviating from the scope of the present disclosure.
The binders 514 may be disposed around the buffer tubes 504. The binders 514 may be adapted to bind the buffer tubes 504 that may be arranged around the CSM 501.
The yarns 506 may be disposed around the buffer tubes 504. Each yarn of the yarns 506 may be a super absorbent polymer impregnated high tenacity polyester fiber base swellable yarn. The yarns 506 may be adapted to block water to enter in the buffer tubes 504. Specifically, the yarns 506 may provide water resistance to the buffer tubes 504 over longer period of time. The yarns 506 may therefore facilitate complete water insulation and may protect the buffer tubes 504 against water ingression.
The ripcords 508 may be disposed near to the periphery of the optical fiber cable 500. Specifically, the ripcords 508 may be disposed near to the inner periphery of the optical fiber cable 500. In other words, the ripcords 508 may be disposed adjacent to the sheath layer 512. The ripcords 508 may be adapted to tear apart the sheath layers 512 to facilitate access to the buffer tubes 504 that may be enclosed inside the optical fiber cable 500.
In some aspects of the present disclosure, each ripcord of the ripcords 508 may be made up of a material, including but not limited to, aramid yarn, fiberglass epoxy, and steel. Aspects of the present disclosure are intended to include and/or otherwise cover any type of material for each ripcord of the ripcords 508, without deviating from the scope of the present disclosure.
The sheath layers 512 may be disposed along on an outer periphery of the optical fiber cable 500. The sheath layers 512 may enclose a plurality of strength members 516a-516n (hereinafter collectively referred to and designated as “the strength members 516”). The strength members 516 may provide the required tensile strength and stiffness to the optical fiber cable 500. Each strength member of the strength members 516 may be made up of a material, having but not limited to, a reinforced aramid yarn, a reinforced glass yarn, and steel. Aspects of the present disclosure are intended to include and/or otherwise cover any type of material for each strength member of the strength members 516, without deviating from the scope of the present disclosure.
In some aspects of the present disclosure, the sheath layers 512 may be made up of a material, including but not limited to, polyethylene, thermoplastic polyurethane, low smoke zero halogen (LSZH), and the like. Aspects of the present disclosure are intended to include and/or otherwise cover any type of material for the sheath layers 512, without deviating from the scope of the present disclosure.
Thus, the optical fiber 100 of the present disclosure may be advantageously manufactured in a cost-effective way because of less fluorination. The optical fiber 100 may be advantageously used in an application where less macro bend is not a compulsion. The optical fiber 100 may advantageously be a cost-effective solution in case of access network application. Further, the optical fiber 100 of the present disclosure provides ultra-low bend losses as well as optimized mode field diameter (MFD) values which complies with the ITU-T G.652.D and G.657.A1 recommendations and even improved optical properties as compared to the ITU-T G.652.D and G.657.A1 recommendations.
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. , Claims:I/We Claim(s):
1. An optical fiber (100, 101, 103, 105, 107) comprising:
one or more core regions (102) such that the one or more core regions (102) is an up doped region (208, 308); and
a cladding region (104) that surrounds the one or more core regions (102);
where the cladding region (104) has exactly one down doped region (210, 310) and an undoped region (212, 312), where the down doped region (210, 310) is a continuous region adjacent to the one or more core region (102) such that a radial position of minimum relative refractive index (214, 314) of the optical fiber (100, 101, 103, 105, 107) is within three micrometres (µm) from an interface between the down doped region (210, 310) and the undoped region (212, 312), where the optical fiber (100, 101, 103, 105, 107) has a mode field diameter in a range of 8.8 µm to 9.6 µm at a wavelength 1310 nanometres (nm), where the optical fiber (100, 101, 103, 105, 107) has a cable cut-off of less than or equal to 1260 nm.

2. The optical fiber (100, 101, 103, 105, 107) of claim 1, where the down doped region (210, 310) has a trench volume in a range of 3 to 4.5 µm2.

3. The optical fiber (100, 101, 103, 105, 107) of claim 1, where the down doped region (210, 310) has a trench alpha in range of 1 to 3.

4. The optical fiber (100, 101, 103, 105, 107) of claim 1, the down doped region (210, 310) has a minimum relative refractive index (214, 314) in a range of -0.05 to -0.21 %.

5. The optical fiber (100, 101, 103, 105, 107) of claim 1, where the down doped region (210, 310) has a thickness in a range of 8 µm to 12 µm.

6. The optical fiber (100, 101, 103, 105, 107) of claim 1, where the one or more core regions (102) does not have a sharp peak at a center (R0) of the one or more core regions.

7. The optical fiber (100, 101, 103, 105, 107) of claim 1, where (i) an attenuation of the optical fiber (100, 101, 103, 105) at 1310 nm wavelength is less than or equal to 0.33 Decibel (dB), (ii) an attenuation of the optical fiber (100, 101, 103, 105, 107) at 1383 nm wavelength is less than or equal to 0.31 dB, (iii) an attenuation of the optical fiber (100, 101, 103, 105, 107) at 1550 nm wavelength is less than or equal to 0.19 dB, and (iv) an attenuation of the optical fiber (100, 101, 103, 105, 107) at 1625 nm wavelength is less than or equal to 0.21 dB.

8. The optical fiber (100, 101, 103, 105, 107) of claim 1, where at least one of (i) a macro bend loss of the optical fiber (100, 101, 103, 105, 107) at 10 mm bend radius and 1625 nm wavelength is less than or equal to 1.5 dB/turn and (ii) a macro bend loss of the optical fiber (100, 101, 103, 105, 107) at 15 mm bend radius and 1625 nm wavelength is less than or equal to 0.3 dB/turn.

9. The optical fiber (100, 101, 103, 105, 107) of claim 1, where the core region (102) has (i) a core volume in a range of 4.5 to 5.5 µm2, (ii) a core relative refractive index in a range of 0.37 to 0.44 %, and (iii) a core alpha value in a range of 3 to 6.

10. The optical fiber (100, 101, 103, 105, 107) of claim 1, where (i) a primary coating layer (108) surrounding the cladding region (104) has a young’s modulus in a range of 0.1 to 0.3 MPa and (ii) a secondary coating layer (112) surrounding the primary coating layer (108) has a young’s modulus in a range of 1200 to 1500 MPa.

11. The optical fiber (100, 101, 103, 105, 107) of claim 1 is used in an optical fiber ribbon (400) such that adjacent optical fibers are bonded.

12. The optical fiber (100, 101, 103, 105, 107) of claim 1 is used in an optical fiber ribbon (400) where at least one pair of adjacent optical fibers are bonded intermittently.