Description:TECHNICAL FIELD
The present disclosure relates generally to optical fibers, and more particularly to an optical fiber cable and an optical fiber with reduced diameter.
BACKGROUND
An increasing demand of high-speed optical fiber communication has increased the density of optical fiber networks, which leads to a larger problem of accommodation of the optical fiber cables. Attenuation of optical signals and micro-bending losses in the optical fibers have a huge impact on a range and quality of optical signal communicated in the network.
Prior art reference “US9802858B2” discloses an optical fiber with a core and a cladding such that the core is co-doped with Fluorine and Chlorine. The cladding of the optical fiber has three cladding layers such that each layer contains silicon dioxide (SiO2) doped with Fluorine and other dopants such as Chlorine and Bromine. The cladding comprises a trench. Another prior art reference “US8472770B2” discloses an optical fiber comprising a core and a cladding such that the cladding includes an inner trench and an outer trench. The outermost layer of the optical fiber is un doped. The trenches formed in the known optical fiber in the prior art is not at the outer region of the optical fiber.
In multicore optical fiber, an outer trench is known in the prior art which primarily focus on improving inter core cross talk specifically in a case of reduced diameter multicore optical fiber where the glass diameter of the optical fiber is significantly low. The design parameters for multicore optical fibers include pitch, outer clad thickness (OCT), and refractive index (RI) structures of the core. The OCT represents the minimum distance between a center of the outer cores and the interface between the cladding and the coating. To compensate for the low OCT resulting from an increase in pitch (which is necessary to reduce crosstalk) and reduction in the glass diameter, the outer cladding layer is optimized. The overall design is optimized to achieve improved crosstalk performance and bend characteristics. In single mode fiber, leakage loss is one of the important optical parameters that need to be controlled. If the leakage loss of the optical fiber is more, then the optical fiber exhibits more attenuation.
Thus, there is a need to develop a single mode optical fiber that is inexpensive, easy to manufacture, reduced in diameter, has increased glass strength, reduced leakage loss and provides ultra-low bend losses as well as optimized mode field diameter (MFD) values.
SUMMARY
In an aspect of the present disclosure, an optical fiber has a core and a cladding. The core extends along a central axis of the optical fiber, and the cladding surrounds the core. The cladding has a peripheral cladding layer. The peripheral cladding layer is defined by a predefined peripheral thickness, and a peripheral refractive index (i.e., a fifth refractive index). The fifth refractive index is less than a refractive index of pure silica. A leakage loss of the optical fiber is less than or equal to 0.003 decibel per kilometer (dB/Km) at a wavelength 1550 nano meter (nm).
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. 1 illustrates an optical fiber.
FIG. 2A illustrates a theoretical refractive index profile of the optical fiber of FIG. 1.
FIG. 2B illustrates an experimental refractive index profile of the optical fiber of FIG. 1.
FIG. 3 illustrates an optical fiber cable manufactured from the optical fiber of FIG. 1.
DEFINITIONS
The term “sheath” as used herein is referred to as an outermost layer or an outermost layer of the optical fiber cable that holds and protects the contents of the optical fiber cable.
The term “strength member” as used herein is referred to as a cable element made up of filaments or yarns that provides strength to the optical fiber cable.
The term “ribbon bundle” as used herein is referred to as a bundle of optical fiber ribbons.
The term “intermittently bonded fiber (IBR)” as used herein refers to an optical fiber ribbon having a plurality of optical fibers such that the plurality of optical fibers is intermittently bonded to each other by a plurality of bonded portions that are placed along the length of the plurality of optical fibers. The plurality of bonded portions is separated by a plurality of unbonded portions. An intermittently bonded ribbon fiber cable consists of fibers bonded using matrix material. As such, they lack a flat structure. The rollable ribbons in an intermittently bonded ribbon fiber are bundled together and have the appearance of a spider’s web. Hence, they are also called spider web ribbon fiber. Due to their loose fiber bundling, intermittently bonded ribbon cables are perfect for making optic fiber cables with higher packing density.
The term “core” as used herein refers to an inner most cylindrical structure present in the center 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 include an inner cladding layer coupled to the outer surface of the core of the optical fiber and an outer cladding layer coupled to the inner cladding from the outside.
The term “trench” as used herein is 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 and increase the relative refractive index of the core with respect to the down-doped region.
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 referred to as a measure of the relative difference in refractive index between two optical materials. As used herein, the relative refractive index 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 is referred to as an optical fiber as disclosed in the present disclosure having a diameter range of 60 micrometers (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 “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 (F).
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 “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 “diameter of the optical fiber” as used herein is referred to as a diameter of a bare glass optical fiber excluding one or more coatings on the optical fiber.
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 includes 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 “bare optical fiber” as used herein is referred to as the uncoated fiber drawn by melting a cylindrical glass preform in a draw tower. Further, the bare optical fiber is coated with one or more coatings.
The term “peripheral cladding layer” as used herein is referred to as the outermost cladding region of the optical fiber. In a reduced diameter fiber, the thickness of the peripheral cladding layer is less so it is down doped with Fluorine till the end of the glass region of the optical fiber to significantly improve leakage loss and micro bending loss. Further the down doping of the peripheral cladding layer helps in increasing the mechanical strength of the optical fiber.
The term “leakage loss” as used herein is referred to as loss due to mode leak in an optical fiber that adds to an attenuation of the optical fiber. The leakage loss is calculated using finite element analysis method where the losses are calculated in the fiber in straight condition.
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 Rayleigh scattering, absorption of the light signal, and the like.
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.
The term “core peak” as used herein is referred to as the maximum relative refractive index value of the core 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. 1 illustrates an optical fiber 100, according to an aspect of the present disclosure. The optical fiber 100 may have a leakage loss less than or equal to 0.003 decibel per kilometer (dB/Km) at a wavelength 1550 nano meter (nm). In some aspects of the present disclosure, the optical fiber 100 may have a Mode Field Diameter (MFD) in a range of 8.2 micro meter (µm) to 9 µm at a wavelength of 1550 nm. The optical fiber 100 may have a cable cut-off wavelength less than or equal to 1260 nm.
The optical fiber 100 may have a Co-efficient of Thermal Expansion (CTE) in a range of 6 x 10-7 to 1 x 10-7 per Celsius (C-1). The optical fiber 100 may have an attenuation less than 0.35 decibel/kilometer (dB/KM) at a wavelength of 1310 nm and 0.25 dB/KM at the wavelength of 1550 nm.
In some aspects of the present disclosure, a macro bend loss of the optical fiber 100 may be less than or equal to at least one of, 0.15 dB/turn at a bend radius of 5 milli meter (mm) and a wavelength of 1550 nm, 0.45 dB/turn at a bend radius of 5 mm and a wavelength of 1625 nm, 0.08 dB/turn at a bend radius of 7.5 mm and a wavelength of 1550 nm, and 0.25 dB/turn at a bend radius of 7.5 mm and a wavelength of 1625 nm.
In some aspects of the present disclosure, a glass diameter of the optical fiber 100 may be in a range of 60 µm to 100 µm with a tolerance of + 0.7 µm. In some aspects of the present disclosure, the glass diameter of the optical fiber 100 may be less than 125 µm with a tolerance of + 0.7 µm.
In some aspects of the present disclosure, the optical fiber 100 may coated by a primary coating (not shown) and a secondary coating (not shown) such that a ratio of a thickness of the primary coating to a thickness of the secondary coating may be greater than 0.14. In some aspects of the present disclosure, the optical fiber 100 may be coated with coated with the primary coating layer and the secondary coating layer such that the secondary layer may be colored. In some aspects of the present disclosure, a young’s modulus of the primary coating may be less than 0.6 Mega Pascal (MPa). The young’s modulus of the secondary coating may be less than 1500 MPa.
In some other aspects of the present disclosure, the optical fiber 100 may be coated with at least one layer of coating. The at least one layer of coating may have a thickness of less than or equal to 65 µm.
In some other aspects of the present disclosure, the optical fiber 100 may be coated with coated with the primary coating layer, the secondary coating layer, and the colored coating layer.
In some aspects of the present disclosure, a coating thickness of the primary coating layer may be in a range of 10 µm to 30 µm. In some aspects of the present disclosure, a coating thickness of the secondary layer may be in a range of 10 µm to 30 µm. In some aspects of the present disclosure, a coating thickness of the colored coating layer may be in a range of 4 µm to 8 µm.
In some aspects of the present disclosure, the optical fiber 100 may be coated with a single coating layer. The coating layer may provide tensile strength, rigidity, and enough cushion to the optical fiber 100. Due to the single coating layer, a diameter of the optical fiber 100 with coating may be less than or equal to140 µm.
In some other aspects of the present disclosure, a diameter of the optical fiber 100 that may be coated by at least one coating layer may be in a range of 125 µm to 180 µm. In some other aspects of the present disclosure, the diameter of the optical fiber 100 that may be coated by at least one coating layer may be in a range of 160 µm to 200 µm. In some other aspects of the present disclosure, the diameter of the optical fiber 100 that may be coated by at least one coating layer may be less than 250 µm.
The optical fiber 100 may have a core 102 that may extend along a central axis 101 of the optical fiber 100, and a cladding 104 that may surround the core 102. In some aspects of the present disclosure, the core 102 may be doped with Germanium (Ge). In some other aspects of the present disclosure, the core 102 may be doped with Chlorine (Cl), and any other up dopants.
The cladding may have a peripheral cladding layer 104d. The peripheral cladding layer 104d may be defined by a predefined peripheral thickness, and a fifth refractive index ‘n5’ (i.e., a peripheral refractive index). The fifth refractive index ‘n5’ may be less than a refractive index of pure silica. In some aspects of the present disclosure, the peripheral cladding layer 104d may have a peripheral thickness such that a numerical value of the predefined peripheral thickness of the peripheral cladding layer 104d may be at least 4 micro meters (µm). In some aspects of the present disclosure, a maximum concentration of at least one down dopant in the peripheral cladding layer 104d may be less than or equal to 7 atomic percent (at %). The minimum required numerical value of the predefined peripheral thickness is 4 µm to achieve the required strength, leakage loss, and other optical parameters in the optical fiber 100 as described in the different embodiments of the present disclosure.
In some aspects of the present disclosure, the cladding 104 may further have an inner cladding 104b and a mid-cladding 104c. The inner cladding 104b and may have a third refractive index ‘n3’. A numerical value of the third refractive index ‘n3’ may be less than the refractive index of pure silica. The inner cladding 104b may be down doped with one or more down dopants. The mid-cladding 104c may separate the inner cladding 104b and the peripheral cladding layer 104d. The mid-cladding 104c may have a fourth refractive index ‘n4’ that may be equal to the refractive index of pure silica. The pure silica mid-cladding 104c acts as a buffer region and these are required to optimize the MFD value in the required range as claimed in the present invention. The inner cladding 104b is important to achieve improved macro bend, MFD, leakage loss and other optical parameters. In some aspects of the present disclosure a concentration profile of at least one down dopant is maximum between an outer boundary 104ba of the core 102 and an outer boundary 104bb of the inner cladding 104b. In some aspects of the present disclosure, the outer boundary 104ba of the core 102 and the outer boundary 104bb of the inner cladding 104b may be identified by first order differentiation of relative refractive index with respect to radial parameters. In some aspects of the present disclosure, the outer boundary 104ba of the core 102 and the outer boundary 104bb of the inner cladding 104b may be identified by a change in slope in the refractive index profile 202b of FIG. 2B.
In some aspects of the present disclosure, the cladding 104 may further have an intermediate cladding 104a that may surround the core 102. The intermediate cladding 104a may be un doped. In some aspects of the present disclosure, the radial thickness of the intermediate cladding 104a is zero.
In some aspects of the present disclosure, the cladding 104 may have at least one region having a relative refractive index less than the relative refractive index of pure silica. The cladding 104 may further have at least one region of a predefined thickness having a relative refractive index equal to the relative refractive index of pure silica. The predefined thickness may be defined as an absolute difference between the radii of the two adjacent cladding regions.
In some aspects of the present disclosure, the core 102 may extend from a first radial distance R1 to the central axis 101, and the cladding 104 may extend from a fifth radial distance R5 to the first radial distance R1, from the central axis 101. In some aspects of the present disclosure, the intermediate cladding 104a may extend from a second radial distance R2 to the first radial distance R1, from the central axis 101. The inner cladding 104b may extend from a third radial distance R3 to the second radial distance R2, from the central axis 101. The mid-cladding 104c may extend from a fourth radial distance R4 to the third radial distance R3, from the central axis 101. The peripheral cladding layer 104d may extend from the fifth radial distance R5 to the fourth radial distance R4, from the central axis 101.
In some aspects of the present disclosure, a numerical range of the first radial distance R1 may be in a range of 3.5 µm to 5 µm. A numerical value of a difference in the second radial distance R2 and the first radial distance R1 (i.e., R2-R1) may be in a range of 0 µm to 8.5 µm. A numerical range of the third radial distance R3 may be in a range of 10 µm to 20 µm. A numerical range of the fourth radial distance R4 may be in a range of 20 µm to 60 µm. A numerical range of the fifth radial distance R5 may be in a range of 30 µm to 62.5 µm, with a tolerance of 0.35 µm. In some aspects of the present disclosure, the difference of second radial distance R2 and first radial distance R1 may be equal to 0 µm which defines that the optical fiber 100 is independent of any intermediate cladding 104a. In other words, the optical fiber 100 may be free from any buffer region or pure silica region or un doped region immediately adjacent to the core 102.
FIG. 2A illustrates a theoretical refractive index profile 200 of the optical fiber 100 of FIG. 1. FIG. 2B illustrates an experimental refractive index profile 200 of the optical fiber 100 of FIG. 1. As mentioned above, the optical fiber 100 may have the core 102 and the cladding 104. The cladding 104 may further have the intermediate cladding 104a, the inner cladding 104b, the mid-cladding 104c, and the peripheral cladding layer 104d. The core 102 may have a first relative refractive index ‘?1’. In some aspects of the present disclosure, a numerical value of the first relative refractive index ‘?1’ may be in a range of 0.35 to 0.45. In some aspects of the present disclosure, the relative refractive index profile of the core 102 may have an alpha profile such that a first refractive index (i.e., core refractive index) ‘n1’ may be derived from a peak shaping parameter ‘’. The peak shaping parameter ‘’ is defined as how refractive index changes as a function of radius. In some aspects of the present disclosure, a numerical value of the peak shaping parameter ‘’ may be in a range of 3 to 9. The core refractive index ‘n1’ may further be dependent on a core peak with a maximum refractive index value ‘n1max’ (i.e., a maximum value of the core refractive index ‘n1’), the core radius ‘R1’, the first relative refractive index difference ‘?1’, 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 ‘n1’ at the radial distance ‘r’ can be determined as:
n1r=n1max1-2?1rR1a112.
The intermediate cladding 104a may have a second relative refractive index ‘?2’. In some aspects of the present disclosure, a numerical value of the second relative refractive index ‘?2’ may be in a range of -0.05 to 0.05. The inner cladding 104b may have a third relative refractive index ‘?3’. In some aspects of the present disclosure, a numerical value of the third relative refractive index (?3) is less than a relative refractive index of pure silica. In some aspects of the present disclosure, the numerical value of the third relative refractive index ‘?3’ may be in a range of -0.2 to -0.45.
The mid-cladding 104c may have a fourth relative refractive index ‘?4’. In some aspects of the present disclosure, a numerical value of the fourth relative refractive index ‘?4’ may be in a range of -0.05 to 0.05. The peripheral cladding layer 104d may have a fifth relative refractive index ‘?5’. In some aspects of the present disclosure, a numerical value of the fifth relative refractive index ‘?5’ may be in a range of -0.05 to -0.35. In some aspects of the present disclosure, a numerical value of the fifth relative refractive index ‘?5’ at an outermost end 105 (as shown earlier in FIG. 1) of the peripheral cladding layer 104d may be less than or equal to a minimum value ‘?5min’ of the fifth relative refractive index ‘?5’. In one exemplary aspect of the present invention the minimum value ‘?5min’ may be equal to -0.35. In some aspects of the present disclosure, an absolute difference in the fifth relative refractive index ‘?5’ and the relative refractive index of pure silica may be less than or equal to 0.3%.
In an exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.5 µm. The cable cut-off wavelength may be equal to 1210 nm. A zero-dispersion wavelength (ZDW) may be less than or equal to 1316 nm. The macro bend loss may be at least one of, 0.1 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.3 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.04 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.11 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.0004 dB/Km at the wavelength of 1550 nm when the glass diameter of the optical fiber 100 is equal to 60 µm. The first relative refractive index ‘?1’ may be equal to 0.41, the first radial distance ‘R1’ may be equal to 3.82 µm, the peak shaping parameter ‘’ may be equal to 4, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 4.3 µm, the third relative refractive index ‘?3’ may be equal to -0.32, the third radial distance R3 may be equal to 15 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 25 µm, the fifth relative refractive index ‘?5’ may be equal to -0.2, the fifth radial distance R5 may be equal to 30 µm.
In another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.5 µm. The cable cut-off wavelength may be equal to 1210 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1316 nm. The macro bend loss may be at least one of, 0.1 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.3 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.04 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.11 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.0003 dB/Km at the wavelength of 1550 nm when the glass diameter of the optical fiber is equal to 80 µm. The first relative refractive index ‘?1’ may be equal to 0.41, the first radial distance ‘R1’ may be equal to 3.82 µm, the peak shaping parameter ‘’ may be equal to 4, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 4.3 µm, the third relative refractive index ‘?3’ may be equal to -0.32, the third radial distance R3 may be equal to 15 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 35 µm, the fifth relative refractive index ‘?5’ may be equal to -0.2, the fifth radial distance R5 may be equal to 40 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.5 µm. The cable cut-off wavelength may be equal to 1210 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1316 nm. The macro bend loss may be at least one of, 0.1 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.3 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.04 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.11 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.0001 dB/Km at the wavelength of 1550 nm when the glass diameter of the optical fiber 100 is equal to 100 µm. The first relative refractive index ‘?1’ may be equal to 0.41, the first radial distance ‘R1’ may be equal to 3.82 µm, the peak shaping parameter ‘’ may be equal to 4, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 4.3 µm, the third relative refractive index ‘?3’ may be equal to -0.32, the third radial distance R3 may be equal to 15 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 45 µm, the fifth relative refractive index ‘?5’ may be equal to -0.2, the fifth radial distance R5 may be equal to 50 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.5 µm. The cable cut-off wavelength may be equal to 1210 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1316 nm. The macro bend loss may be at least one of, 0.1 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.3 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.04 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm. The optical fiber 100 may have a leakage loss of0.000008 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 125 µm. The first relative refractive index ‘?1’ may be equal to 0.41, the first radial distance ‘R1’ may be equal to 3.82 µm, the peak shaping parameter ‘’ may be equal to 4, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 4.3 µm, the third relative refractive index ‘?3’ may be equal to -0.32, the third radial distance R3 may be equal to 15 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 55 µm, the fifth relative refractive index ‘?5’ may be equal to -0.2, the fifth radial distance R5 may be equal to 62.5 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.8 µm. The cable cut-off wavelength may be equal to 1240 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1312 nm. The macro bend loss may be at least one of, 0.12 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.34 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.08 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.24 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.00062 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 60 µm. The first relative refractive index ‘?1’ may be equal to 0.38, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 5, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 0 µm, the third relative refractive index ‘?3’ may be equal to -0.2, the third radial distance R3 may be equal to 12 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 23 µm, the fifth relative refractive index ‘?5’ may be equal to -0.1, the fifth radial distance R5 may be equal to 30 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.8 µm. The cable cut-off wavelength may be to 1240 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1312 nm. The macro bend loss may be at least one of, 0.12 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.34 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.08 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.24 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.0004 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber is equal to 80 µm. The first relative refractive index ‘?1’ may be equal to 0.38, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 5, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 0 µm, the third relative refractive index ‘?3’ may be equal to -0.2, the third radial distance R3 may be equal to 12 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 33 µm, the fifth relative refractive index ‘?5’ may be equal to -0.1, the fifth radial distance R5 may be equal to 40 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.8 µm. The cable cut-off wavelength may be equal to 1240 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1312 nm. The macro bend loss may be at least one of, 0.12 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.34 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.08 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.24 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.00015 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is 100 µm. The first relative refractive index ‘?1’ may be equal to 0.38, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 5, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 0 µm, the third relative refractive index ‘?3’ may be equal to -0.2, the third radial distance R3 may be equal to 12 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 42 µm, the fifth relative refractive index ‘?5’ may be equal to -0.1, the fifth radial distance R5 may be equal to 50 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.8 µm. The cable cut-off wavelength may be equal to 1240 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1312 nm. The macro bend loss may be at least one of, 0.12 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.34 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.08 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.24 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.000009 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 125 µm. The first relative refractive index ‘?1’ may be equal to 0.38, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 5, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 0 µm, the third relative refractive index ‘?3’ may be equal to -0.2, the third radial distance R3 may be equal to 12 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 54 µm, the fifth relative refractive index ‘?5’ may be equal to -0.1, the fifth radial distance R5 may be equal to 62.5 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.35 µm. The cable cut-off wavelength may be equal to 1250 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1317 nm. The macro bend loss may be at least one of, 0.08 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.22 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.02 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.05 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.00038 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 60 µm. The first relative refractive index ‘?1’ may be equal to 0.42, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 3, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 6 µm, the third relative refractive index ‘?3’ may be equal to -0.28, the third radial distance R3 may be equal to 18 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 26 µm, the fifth relative refractive index ‘?5’ may be equal to -0.3, the fifth radial distance R5 may be equal to 30 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.35 µm. The cable cut-off wavelength may be equal to 1250 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1317 nm. The macro bend loss may be at least one of, 0.08 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.22 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.02 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.05 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.00024 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber is equal to 80 µm. The first relative refractive index ‘?1’ may be equal to 0.42, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 3, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 6 µm, the third relative refractive index ‘?3’ may be equal to -0.28, the third radial distance R3 may be equal to 18 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 36 µm, the fifth relative refractive index ‘?5’ may be equal to -0.3, the fifth radial distance R5 may be equal to 40 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.35 µm. The cable cut-off wavelength may be equal to 1250 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1317 nm. The macro bend loss may be at least one of, 0.08 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.22 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.02 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.05 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber may have a leakage loss of 0.00008 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 100 µm. The first relative refractive index ‘?1’ may be equal to 0.42, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 3, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 6 µm, the third relative refractive index ‘?3’ may be equal to -0.28, the third radial distance R3 may be equal to 18 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 46 µm, the fifth relative refractive index ‘?5’ may be equal to -0.3, the fifth radial distance R5 may be equal to 50 µm.
In yet another exemplary aspect of the present disclosure, the optical fiber 100 may have the MFD of 8.35 µm. The cable cut-off wavelength may be equal to 1250 nm. The zero-dispersion wavelength (ZDW) may be less than or equal to 1317 nm. The macro bend loss may be at least one of, 0.08 dB/turn at the bend radius of 5 milli meter (mm) and the wavelength of 1550 nm, 0.22 dB/turn at the bend radius of 5 mm and the wavelength of 1625 nm, 0.02 dB/turn at the bend radius of 7.5 mm and the wavelength of 1550 nm, and 0.05 dB/turn at the bend radius of 7.5 mm and the wavelength of 1625 nm. The optical fiber 100 may have a leakage loss of 0.0000002 dB/Km at the wavelength of 1550 nm when the diameter of the optical fiber 100 is equal to 125 µm. The first relative refractive index ‘?1’ may be equal to 0.42, the first radial distance ‘R1’ may be equal to 4 µm, the peak shaping parameter ‘’ may be equal to 3, the second relative refractive index ‘?2’ may be equal to 0, the difference between the second radial distance and the first radial distance (R2-R1) may be equal to 6 µm, the third relative refractive index ‘?3’ may be equal to -0.28, the third radial distance R3 may be equal to 18 µm, the fourth relative refractive index ‘?4’ may be equal to 0, the fourth radial distance R4 may be equal to 58 µm, the fifth relative refractive index ‘?5’ may be equal to -0.3, the fifth radial distance R5 may be equal to 62.5 µm.
FIG. 3 illustrates an optical fiber cable 300. Preferably, the optical fiber cable 300 may be a ribbon fiber cable. More specifically, the optical fiber cable 300 may be an intermittent bonded ribbon (IBR) fiber cable. In some aspects of the present disclosure, an attenuation of the optical fiber cable 300 may be less than 0.25 dB/km at the wavelength 1310 nm. The attenuation of the optical fiber cable 300 may be less than 0.4 dB/km at the wavelength of 1550 nm.
The optical fiber 300 may have a plurality of buffer tubes 302. Although FIG. 3 illustrates that the plurality of buffer tubes 302 has six buffer tubes (i.e., first through sixth buffer tube 302a-302f), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, the plurality of buffer tubes 302 may have any number of buffer tubes, without deviating from the scope of the present disclosure. In such a scenario, each buffer tube of the plurality of buffer tubes 302 may be structurally and functionally similar to the first through sixth buffer tubes 302a-302f as described herein.
The plurality of buffer tubes 302 may have a plurality of optical fiber ribbons 304 (hereinafter interchangeably referred to and designated as “plurality of IBRs 304”). Although FIG. 3 illustrates that the plurality of buffer tubes 302 has twenty four IBRS (i.e., first through twenty fourth IBR 304a-304x), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, the plurality of buffer tubes 302 may have any number of IBRs, without deviating from the scope of the present disclosure. In such a scenario, each IBR of the plurality of IBRs 304 may be structurally and functionally similar to the first through twenty fourth IBR 304a-304x as described herein. FIG. 3 further illustrates that each buffer tube of the plurality of buffer tubes 302 has four IBRS (for example the first buffer tube 302a is shown to have the first through fourth IBR 304a-302d), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, each buffer tube of the plurality of buffer tubes 302 may have any number of IBRs, without deviating from the scope of the present disclosure. In such a scenario, each IBR of each IBR of the plurality of IBRs 304 may be structurally and functionally similar to the first through twenty fourth IBR 304a-304x as described herein.
Each IBR 302 may have a plurality of optical fibers 100. Each optical fiber of the plurality of optical fibers 100 may have one or more structural and functional properties same as the optical fiber 100. In some aspects of the present disclosure, each optical fiber of the plurality of optical fibers 100 may be same as the optical fiber 100.
In some aspects of the present disclosure, each optical fiber of the plurality of optical fibers 100 (hereinafter interchangeably referred to and designated as “the optical fiber 100”) may have the core 102 that may extend along the central axis 101 of the optical fiber 100, and the cladding 104 that may surround the core 102. In some aspects of the present disclosure, the core 102 may be doped with Germanium (Ge).
The cladding may have the peripheral cladding layer 104d. The peripheral cladding layer 104d may be defined by the predefined peripheral thickness, and the fifth refractive index ‘n5’. The fifth refractive index ‘n5’ may be less than a refractive index of pure silica. In some aspects of the present disclosure, the peripheral cladding layer 104d may have a peripheral thickness such that the numerical value of the predefined peripheral thickness of the peripheral cladding layer 104d may be at least 4 micro meters (µm). In some aspects of the present disclosure, the maximum concentration of the at least one down dopant in the peripheral cladding layer 104d may be less than or equal to 7 atomic percent (at %).
In some aspects of the present disclosure, the cladding 104 may further have the inner cladding 104b and the mid-cladding 104c. The inner cladding 104b may have the third refractive index ‘n3’. The numerical value of the third refractive index ‘n3’ may be less than the refractive index of pure silica. The mid-cladding 104c may separate the inner cladding 104b and the peripheral cladding layer 104d. The mid-cladding 104c may have the fourth refractive index ‘n4’ that may be equal to the refractive index of pure silica.
In some aspects of the present disclosure, the cladding 104 may further have the intermediate cladding 104a that may surround the core 102. The intermediate cladding 104a may be un doped.
In some aspects of the present disclosure, the cladding 104 may have at least one region having the relative refractive index less than the relative refractive index of pure silica. The cladding 104 may further have at least one region that may have the relative refractive index equal to the relative refractive index of pure silica.
The optical fiber cable 300 may further have a sheath 306 that surrounds the plurality of buffer tubes 302. Specifically, the sheath 306 may be adapted to act as an outermost covering for the optical fiber cable 400 such that the sheath 306 facilitates in reduction of abrasion and to provide the optical fiber cable 100 with extra protection against external mechanical effects such as crushing, and the like. In some aspects of the present disclosure, the sheath 306 may be made up of a material such as, but not limited to, a synthetic plastic material, a natural plastic material, and the like. Aspects of the present disclosure are intended to include and/or otherwise cover any type of material for the sheath 306, known to a person of ordinary skill in the art, without deviating from the scope of the present disclosure.
The sheath 306 may have a plurality of strength members 308 that may be partially or completely embedded in the sheath 306. Specifically, the plurality of strength members 308 may be adapted to provide strength to the optical fiber cable 300 that may be required during an installation process of the optical fiber cable 300. Further, the strength members 308 may be adapted to provide majority of structural strength and support to the optical fiber cable 300. Furthermore, the strength members 308 may enhance a tensile strength of the optical fiber cable 300, which is highly desirable during the installation process. Although FIG. 3 illustrates that the plurality of strength members 308 has six strength members (i.e., first through sixth strength members 308a-308f), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, the plurality of strength members 308 may have any number of strength members, without deviating from the scope of the present disclosure. In such a scenario, each strength member of the plurality of strength members 308 may be structurally and functionally similar to the first through sixth strength members 308a-308f as described herein.
Furthermore, the optical fiber cable 300 may have one or more ripcords 310. The one or more ripcords 310 may facilitate ripping, tearing, or opening up of the optical fiber cable 300. In some aspects of the present disclosure, the one or more ripcords 310 may facilitate the ripping, tearing, or opening up of the optical fiber cable 300 to access the plurality of strength members 308 from the sheath 306. Although FIG. 3 illustrates that the one or more ripcords 310 has two ripcords (i.e., first and second ripcords shown as 310a and 310b, respectively), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, the one or more ripcords 310 may have any number of ripcords, without deviating from the scope of the present disclosure. In such a scenario, each ripcord of the one or more ripcords 310 may be structurally and functionally similar to the first and second ripcords 310a, 310b as described herein.
Furthermore, the optical fiber cable 300 may have a plurality of water swellable yarns 312. The plurality of water swellable yarns (WSYs) 312 may provide water resistance to the plurality of optical fibers 100 inside the optical fiber cable 300 by restricting penetration of water inside the optical fiber cable 300. Although FIG. 3 illustrates that the plurality WSYs 312 has five WSYs (i.e., first through fifth WSYs 312a-312e), it will be apparent to a person skilled in the art that the scope of the present disclosure is not limited to it. In various other aspects, the plurality WSYs 312 may have any number of WSYs, without deviating from the scope of the present disclosure. In such a scenario, each WSY of the plurality WSYs 312 may be structurally and functionally similar to the first through fifth WSY 312a-312e as described herein.
The optical fiber 100 provides a reduced diameter in a range of 60 µm to 100 µm. The reduced diameter optical fiber is used in intermittently bonded ribbon (IBR) cable (i.e., the optical fiber cable 300) which significantly improves the packing density of the optical fiber cable 300. Further the additional strength achieved because of the down doped peripheral cladding layer 104d of the optical fiber 100, improves of an overall strength of each ribbon of the plurality of optical fiber ribbons 304, and subsequently a strength of the optical fiber cable 300. In the case of single-mode fibers (SMF), the peripheral cladding layer 104d plays a crucial role in controlling micro bend losses, particularly when reducing the cladding diameter from 125 microns to 60 microns. The primary objective is to reduce leakage loss by optimizing the width and depth of the peripheral cladding layer 104d. Additionally, the peripheral cladding layer 104d provides critical strength to the fiber, especially important for low-clad diameter fibers. Increasing the strength of the fiber due to peripheral cladding layer 104d is vital in the optical fiber cable manufacturing process of optical fibers with low cladding diameter. The peripheral cladding layer 104d that is doped with elements such as Fluorine or Titanium, creates compressive stress on a surface of the optical fiber 100, aiding in achieving a desired strength. In some aspects of the present disclosure, the optical fiber 100 may have a micro bend loss less than or equal to 0.5 dB/Km.
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) comprising:
a core (102) that extends along a central axis (101) of the optical fiber (100); and
a cladding (104) that surrounds the core (102), and comprising a peripheral cladding layer (104d), where the peripheral cladding layer (104d) is defined by a predefined peripheral thickness, and a fifth refractive index (n5), where the fifth refractive index (n5) is less than a refractive index of pure silica;
where, a leakage loss of the optical fiber (100) is less than or equal to 0.003 decibel per kilometer (dB/Km) at a wavelength 1550 nano meter (nm).

2. The optical fiber (100) of claim 1, where a numerical value of the predefined peripheral thickness of the peripheral cladding layer (104d) is at least 4 micro meters (µm).

3. The optical fiber (100) of claim 1, where the peripheral cladding layer (104d) has a fifth relative refractive index (?5) such that a numerical value of the fifth relative refractive index (?5) at an outermost end (105) of the peripheral cladding layer (104d) is less than or equal to a minimum value (?5min) of the fifth relative refractive index (?5).

4. The optical fiber (100) of claim 1, where the cladding (104) further comprising:
an inner cladding (104b) having a third relative refractive index (?3), where a numerical value of the third relative refractive index (?3) is less than a relative refractive index of pure silica; and
a mid-cladding (104c) separating the inner cladding (104b) and the peripheral cladding layer (104d).

5. The optical fiber (100) of claim 1, wherein the cladding (104) further comprising an intermediate cladding (104a) surrounding the core (102), where the intermediate cladding (104a) is un doped.

6. The optical fiber (100) of claim 1, where a concentration profile of at least one down dopant is maximum between an outer boundary (104ba) of the core (102) and an outer boundary (104bb) of the inner cladding (104b).

7. The optical fiber (100) of claim 3, where an absolute difference in the fifth relative refractive index (?5) and the relative refractive index of pure silica is less than or equal to 0.3%.

8. The optical fiber (100) of claim 1, where the cladding (104) comprising at least one region of a predefined thickness where relative refractive index is equal to the relative refractive index of pure silica.

9. The optical fiber (100) of claim 1, where (i) a Mode Field Diameter (MFD) of the optical fiber (100) is in a range of 8.2 micro meter (µm) to 9 µm at a wavelength of 1550 nm, (ii) a cable cut-off wavelength of the optical fiber (100) is less than or equal to 1260 nano meter (nm), (iii) a Co-efficient of Thermal Expansion (CTE) of the optical fiber (100) is in a range of 6 x 10-7 to 1 x 10-7 per Celsius (C-1), and (iv) an attenuation of the optical fiber (100) is less than 0.35 decibel/kilometer (dB/KM) at a wavelength of 1310 nm and 0.25 dB/KM at the wavelength of 1550 nm.

10. The optical fiber (100) of claim 1, where a macro-bend loss of the optical fiber (100) is less than or equal to at least one of, (i) 0.15 dB/turn at a bend radius of 5 milli meter (mm) and a wavelength of 1550 nm, (ii) 0.45 dB/turn at a bend radius of 5 mm and a wavelength of 1625 nm, (iii) 0.2 dB/turn at a bend radius of 7.5 mm and a wavelength of 1550 nm, and (iv) 0.5 dB/turn at a bend radius of 7.5 mm and a wavelength of 1625 nm.

11. The optical fiber (100) of claim 14, where the diameter of the optical fiber (100) is less than 125 µm such that a maximum concentration of at least one down dopant in the peripheral cladding layer (104d) is less than or equal to 7 atomic percent (at %).

12. The optical fiber (100) of claim 1, where the optical fiber (100) is coated by a primary coating and a secondary coating such that a ratio of a thickness of the primary coating to a thickness of the secondary coating is greater than 0.14.

13. The optical fiber (100) of claim 1 is for use in an optical fiber cable (300).

14. The optical fiber (100) of claim 1 used for manufacturing an optical fiber ribbon (304) with at least one pair of adjacent optical fibers is fully bonded along the length and at least one pair of adjacent optical fibers is intermittently bonded along the length.

15. The optical fiber cable (300) of claim 16, where an attenuation of the optical fiber cable (300) is (i) less than 0.4 dB/km at a wavelength of 1310 nm, and (ii) less than 0.25 dB/km at the wavelength of 1550 nm.