Low bending losses at large and small bending diameters and a small diameter optical fiber with a moderate effective area

Abstract

The present disclosure provides a small diameter optical fiber with a moderate effective area at 1550 nm, exhibiting low macrobend loss at 1550 nm, low microbend loss at 1550 nm, and low attenuation at 1550 nm at bend diameters of 32 mm and 50 mm. The optical fiber is coated and has an outer coating diameter of less than 210 μm. The optical fiber has a 20% μm 2 The cladding has a trench cladding region having a trench volume of less than 1000 .mu.m.

Description

[Technical Field]

[0001] This application claims the benefit of priority under 35 U.S.C. § 120 of U.S. Provisional Application No. 63 / 440,945, filed January 25, 2023, the contents of which are herein relied upon and incorporated by reference in their entirety.

[0002] Field of Disclosure This disclosure relates to optical fibers and cables including optical fibers. More particularly, this disclosure relates to small diameter optical fibers that exhibit low attenuation and low bend loss at large bend diameters. [Background technology]

[0003] Background to the disclosure Telecommunications systems require optical fibers capable of transmitting optical signals over long distances at high data rates with low loss. Transmission capacity has been improved through advances in wavelength division multiplexing and modulation formats. Wavelength division multiplexing has increased the number of transmission channels, while advanced modulation formats have increased the data rate per channel. The primary causes of signal loss are attenuation and bending losses. Attenuation losses can be reduced by minimizing Rayleigh scattering within the fiber core, which can be achieved by fabricating optical fiber cores from materials with high purity and very uniform composition.

[0004] Bending losses include losses due to microbending and macrobending. Microbending losses are caused by high-frequency mechanical perturbations due to external stimuli in the optical fiber's deployment environment. Examples include lateral contact of the optical fiber with surfaces (e.g., pipe walls) within the cable. Physically, microbending corresponds to randomly localized small-radius bends (less than approximately 1 mm) acting along the length of the optical fiber. Microbending leads to mode coupling in the optical fiber and power dissipation in the fundamental mode of single-mode fiber to higher-order modes. Macrobending losses are signal losses caused by bending or wrapping the optical fiber. Optical fiber is often physically bent to meet installation requirements in the field (e.g., around corners). The bend diameter is large (more than approximately 2 mm, typically on the order of tens of millimeters), and the loss mechanism is optical leakage. When an optical fiber bends, a portion of the optical signal refracts from the core and dissipates within the protective coating surrounding the fiber. As the optical fiber is bent more tightly (the bend diameter decreases), the amount of lost signal increases.

[0005] Currently, there is an increasing demand for optical fiber and its use in submarine applications. This demand is driven by the rapid growth of internet traffic between different continents. Submarine cables are designed to protect the fibers inside from water damage and other mechanical damage. Deep-sea cables are typically about 17-20 mm in diameter. Optical fibers designed for terrestrial systems are generally used in submarine applications. However, the mechanical environment experienced by optical fibers deployed in submarine cable systems is different from that in terrestrial applications, resulting in unreasonably high macrobend losses in submarine systems.

[0006] There is also a demand for smaller diameter optical fibers for terrestrial and submarine applications. As the diameter of optical fibers decreases, more optical fibers can be packed into a cable with a given cross-sectional area, increasing data transmission capacity. However, increasing the number of fibers leads to higher fiber packing densities, which can increase mechanical perturbations and microbending losses.

[0007] There is also a demand for more efficient extension of the reach of telecommunications systems. As signal transmission distances increase, signal strength decreases, necessitating periodic restoration of signal strength to reach long distances. The repeater units required to restore signal strength increase the cost and complexity of telecommunications systems. One strategy for offsetting optical signal strength loss is to initiate signal transmission at higher power. Signals sent at higher power can propagate for longer distances before signal strength decreases to the point where restoration is required. As a result, the spacing between repeater units can be increased, requiring fewer repeater units for a given transmission length. However, high signal power leads to nonlinear effects in signal transmission that result in losses through other mechanisms.

[0008] A typical strategy for minimizing nonlinear loss is to modify the refractive index profile of the optical fiber to increase the effective area of ​​the optical signal. However, a high effective area leads to higher bending losses. Bending losses can be minimized by reducing the effective area, but reducing the effective area increases nonlinear effects. Attenuation also varies with the effective area, and there has been recent interest in maintaining attenuation below a specified threshold while reducing nonlinear effects by increasing the effective area.

[0009] Thus, there is a trade-off between launch signal power, bending loss, attenuation, nonlinear loss, and effective area. The nature of the trade-off changes and becomes more complex as the fiber diameter decreases. Therefore, there is a need for small diameter optical fibers that have low attenuation and an effective area within a range that minimizes signal loss due to both bending and nonlinear effects. Summary of the Invention

[0010] The present disclosure provides an optical fiber having low attenuation, low bending loss, and low nonlinear loss. Low bending loss is achieved at both large and small bending radii. The optical fiber is suitable for deployment in terrestrial and submarine transmission systems. The relative refractive index profile of the optical fiber includes an alkali-doped core configured to provide low attenuation and an effective area in the range of 115 μm to 135 μm at 1550 nm, and a cladding with a trench configured to minimize macrobending loss at bending diameters greater than 40 mm. In particular, a reduced trench volume compared to standard optical fiber has been shown to lead to reduced macrobending loss. The optical fiber also has a diameter less than that of conventional optical fiber.

[0011] This specification An optical fiber, Radius r1 in the range of 5.5 μm to 9.0 μm, and maximum relative refractive index Δ in the range of -0.05% to 0.05% 1max a core region having a relative refractive index profile Δ1 having a cladding region surrounding and immediately adjacent to the core region, the cladding region comprising: a trench cladding region surrounding the core region, the trench cladding region comprising silica glass and having a radius r3, a relative refractive index Δ3, and a 20% μm 2 a trench cladding region having a trench volume less than a cladding region comprising: an outer cladding region surrounding and immediately adjacent to the trench cladding region, the outer cladding region comprising silica glass having a radius r4 and a relative refractive index Δ4 in the range of −0.40% to −0.20%; a coating surrounding and immediately adjacent the outer cladding region, the coating having an outer radius of less than 110 μm; The optical fiber is 115 μm at 1550 nm. 2 ~135μm 2 and a macrobend loss of less than 0.200 dB / turn at 1550 nm as determined by mandrel wrapping testing using a mandrel having a diameter of 32 mm, a macrobend loss of less than 0.030 dB / turn at 1550 nm as determined by mandrel wrapping testing using a mandrel having a diameter of 50 mm, and a microbend loss of less than 3.0 dB / km at 1550 nm as determined by wrapping with a tension of 30 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3).

[0012] Additional features and advantages will be set forth in the detailed description that follows, and in part will become readily apparent to those skilled in the art from the description, or may be learned by practicing the embodiments set forth in the written description and claims herein, as well as the accompanying drawings.

[0013] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary and are intended to provide an overview or framework for understanding the nature and character of the claims.

[0014] The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings are illustrative of selected aspects of the disclosure and, together with the description, serve to explain the principles and operation of methods, products, and compositions encompassed by the disclosure. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram of a coated optical fiber according to one embodiment. [Figure 2] 1 is a schematic diagram of a typical optical fiber ribbon. [Figure 3] 1 is a schematic diagram of a typical fiber optic cable. [Figure 4A] 1 depicts a cross-sectional view of an optical fiber having a core region, a trench cladding region, an outer cladding region, a primary coating, and a secondary coating. [Figure 4B] 1 depicts a cross-sectional view of an optical fiber having a core region, an offset cladding region, a trench cladding region, an outer cladding region, a primary coating, and a secondary coating. [Figure 5A] 1 depicts the relative refractive index profile of a glass fiber having a core region, a trench cladding region, and an outer cladding region. [Figure 5B] 1 depicts the relative refractive index profile of a glass fiber having a core region, an offset cladding region, a trench cladding region, and an outer cladding region. [Figure 5C] 1 depicts the relative refractive index profile of a glass fiber having a core region, a trench cladding region, and an outer cladding region. [Figure 5D] 1 depicts the relative refractive index profile of a glass fiber having a core region, an offset cladding region, a trench cladding region, and an outer cladding region. [Figure 6A] 1 depicts the relative refractive index profile of a modeled glass fiber. [Figure 6B] 1 depicts the relative refractive index profile of a modeled glass fiber. [Figure 6C] 1 depicts the relative refractive index profile of a modeled glass fiber. [Figure 7A]1 shows the variation of microbending loss with wavelength for a modeled glass fiber at various winding tensions. [Figure 7B] 1 shows the variation of microbending loss with wavelength for a modeled glass fiber at various winding tensions. [Figure 7C] 1 shows the variation of microbending loss with wavelength for a modeled glass fiber at various winding tensions. [Figure 8] 1 depicts the relative refractive index profile of an experimental glass fiber. [Figure 9] 1 shows the microbending losses at 1550 nm for two experimental optical fibers and a comparative optical fiber. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure is provided as an enabling teaching and may be more readily understood by reference to the following description, drawings, examples, and claims. In light of this, those skilled in the art will recognize and appreciate that many changes can be made to various aspects of the embodiments described herein and still obtain beneficial results. It will also be apparent that some of the desirable advantages of the present embodiments can be obtained by selecting some of the features without utilizing other features. Accordingly, those skilled in the art will recognize that many modifications and adaptations are possible, and may even be desirable in certain circumstances, and are part of the present disclosure. Therefore, it should be understood that the present disclosure is not limited to the specific compositions, articles, devices, and methods disclosed, unless otherwise specified. It should also be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting.

[0017] In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings.

[0018] The term "include," "includes," or similar terms means without limitation, that is, inclusive and not exclusive.

[0019] As used herein, the term "about" means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not, and need not be, exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding, measurement error, and other factors known to those of ordinary skill in the art. When a value is said to be about or approximately equal to a particular numerical value, the value is within ±10% of that numerical value. For example, a value of about 10 refers to values ​​from 9 to 11, inclusive. When the term "about" is used in describing values ​​or endpoints of a range, the disclosure should be understood to include the specific value or endpoint referenced. Regardless of whether a numerical value or endpoint of a range in the specification is recited as "about," the numerical value or endpoint of the range is intended to include two embodiments: those modified by "about" and those not modified by "about." It will further be understood that each endpoint of a range is significant both in relation to the other endpoint and independently of the other endpoint.

[0020] The term "about" also refers to all terms within ranges unless otherwise specified. For example, about 1, 2, or 3 is equivalent to about 1, about 2, or about 3, and further includes about 1-3, about 1-2, and about 2-3. Specific and preferred values ​​and ranges disclosed for compositions, ingredients, contents, additives, and the like are for illustrative purposes only; they do not exclude other defined values ​​or other values ​​within defined ranges. The compositions and methods of the present disclosure include those having any value or any combination of values, specific values, more specific values, and preferred values ​​described herein.

[0021] As used herein, the indefinite article "a" or "an" and its corresponding definite article "the" mean at least one, or one or more, unless otherwise specified.

[0022] When a range of numerical values ​​including upper and lower limits is recited herein, unless otherwise specified in specific circumstances, the range is intended to include its endpoints, and all integers and fractions within the range. It is not intended that the scope of the claims be limited to the specific values ​​recited when defining the range. Furthermore, when an amount, concentration, or other value or parameter is given as a range, one or more preferred ranges, or a list of an upper preferred value and a lower preferred value, this should be understood to specifically disclose all ranges formed from any pair of any upper range or preferred value and any lower range or preferred value, regardless of whether such pairs are separately disclosed. Finally, when the term "about" is used in describing a value or endpoint of a range, it should be understood that the disclosure includes the specific value or endpoint referenced. When a numerical value or endpoint of a range is not recited as "about," it is intended that the numerical value or endpoint of the range include two embodiments: those modified by "about" and those not modified by "about."

[0023] As used herein, "comprising" is an open transitional phrase. A list of elements following the transitional phrase "comprising" is a non-exclusive list, such that elements other than the elements specifically named in the list may also be present.

[0024] The term "where" is used as an open transitional phrase to introduce the listing of a series of properties of a structure.

[0025] The terms "comprise" and "include", e.g., "A comprises B", are intended to include the concept of "comprise" as a special case, as in "A consists of B".

[0026] As used herein, the term "or" is inclusive; more specifically, the phrase "A or B" means, for example, "A, B, or both A and B." Exclusive "or" is designated herein by terms such as "either A or B" and "one of A or B."

[0027] As used herein, contact refers to direct contact or indirect contact. Direct contact refers to contact without an intervening material, while indirect contact refers to contact through one or more intervening materials. Elements in direct contact are in contact with each other. Elements in indirect contact are not in contact with each other but are firmly or flexibly joined through one or more intervening materials. Contact refers to bringing two elements into direct or indirect contact. Elements in direct (indirect) contact may be said to be in direct (indirect) contact with each other.

[0028] As used herein, "directly adjacent" means in direct contact and "indirectly adjacent" means in indirect contact. The term "adjacent" encompasses elements that are directly or indirectly adjacent to each other.

[0029] "Optical fiber" refers to a waveguide having a glass portion surrounded by a coating, the glass portion including a core and a cladding, referred to herein as a "glass fiber."

[0030] "Radial position," "radius," or radial coordinate "r" refers to the radial position relative to the centerline of the glass fiber (r=0).

[0031] The term "mode" refers to a guided mode. A single-mode optical fiber is an optical fiber designed to support only the fundamental LP01 mode over a substantial length of the optical fiber (e.g., at least several meters), but can support multiple modes over short distances (e.g., tens of centimeters) under certain circumstances. The optical fiber disclosed herein is preferably a single-mode optical fiber at a wavelength of 1550 nm.

[0032] "Refractive index" refers to the refractive index at a wavelength of 1550 nm.

[0033] A "refractive index profile" is the relationship between refractive index or relative refractive index and radius. For relative refractive index profiles depicted herein as having step boundaries between adjacent core and / or cladding regions, normal variations in processing conditions may prevent obtaining a sharp step boundary at the interface between the adjacent regions. While the boundaries of the refractive index profile may be depicted herein as step changes in refractive index, it is understood that the actual boundaries may be rounded or otherwise deviate from a perfect step function characteristic. Furthermore, it is understood that the value of the relative refractive index may vary with radial position within either the core and / or cladding regions. When the relative refractive index varies with radial position in a particular region of the fiber (e.g., either the core and / or cladding regions), the relative refractive index is expressed as its actual or approximate functional dependence, or as its value at a particular location within the region, or as an average value applicable to the entire region. Unless otherwise specified, when the relative refractive index of a region (e.g., either the core region and / or the cladding region) is expressed as a single value or as a parameter applicable to the entire region (e.g., Δ or Δ%), it is understood that the relative refractive index within the region is constant or nearly constant and corresponds to this single value, or that this single value or parameter represents an average value of the non-constant relative refractive index that is dependent on radial position in the region. For example, if "i" is a region of a glass fiber, then the parameter Δ i is, unless otherwise specified, a constant or nearly constant value of the relative refractive index in region i, or Δ ave The dependence of the relative refractive index on radial position may be sloped, curved, or otherwise non-constant, whether by design or as a result of normal manufacturing variations.

[0034] As used herein, the "relative refractive index" is defined by the formula (1):

number

[0035] The average relative refractive index (Δ ave ) is expressed as equation (2):

number

[0036] The term "α profile" refers to the equation (3):

number

number

[0037] The "effective area" of an optical fiber is

number

[0038] The "mode field diameter" or "MFD" of an optical fiber is given by Equation (5):

number

[0039] A "trench" or "trench region" or "trench cladding region" refers to a portion of the cladding that is surrounded by and immediately adjacent to the outer cladding region. The trench is located between the outer radius r1 of the core and the inner radius r3 of the outer cladding region and has a relative refractive index Δ3 that is less than the relative refractive index Δ4 of the outer cladding region. In some embodiments, the trench is directly adjacent to the core. In other embodiments, an offset cladding region surrounds and is directly adjacent to the core, and the trench surrounds and is directly adjacent to the offset cladding region, where the offset cladding region has a relative refractive index Δ2 that is greater than the relative refractive index Δ3 of the trench cladding region and greater than or equal to the relative refractive index Δ4 of the outer cladding region.

[0040] "Trench volume" is a characteristic of the trench cladding region; and

number

[0041] The cutoff wavelength of an optical fiber is the smallest wavelength at which the optical fiber supports only one propagation mode. The cutoff wavelength is reported herein as the cabled cutoff wavelength. The cabled cutoff wavelength is based on a cabled fiber length of 22 meters. The cabled cutoff wavelength is based on the 22 meter cabled fiber length specified by the Telecommunications Industry Association (TIA) in TIA-455-80:FOTP-80 IEC-60793-1-44 Optical Fibers - Part 1-44: Measurement Methods and Test Procedures - Cut-off Wavelength (May 21, 2003).

[0042] The term "bend diameter" refers to the diameter of the mandrel used to determine macrobend loss using the mandrel wrapping test specified in standard TIA-455-62:FOTP-62 IEC-60793-1-47 Optical Fibers - Part 1-47: Measurement Methods and Test Procedures - Macrobending Loss by the Telecommunications Industry Association (TIA).

[0043] The optical fiber disclosed herein includes a core region, a cladding region surrounding the core region, and a coating surrounding the cladding region. The core region and the cladding region are glass. The cladding region includes multiple regions with different relative refractive indices. The multiple cladding regions are preferably concentric regions. In preferred embodiments, the cladding region includes a trench cladding region. The trench cladding region surrounds the core region and is surrounded by and directly adjacent to the outer cladding region. In some embodiments, the trench cladding region is directly adjacent to the core region. In other embodiments, the trench cladding region is directly adjacent to the offset cladding region, which is directly adjacent to the core region. The core region, cladding region, trench cladding region, and outer cladding region are also referred to as the core, cladding, trench, and outer cladding, respectively. The offset cladding region is optional and may also be referred to herein as the offset.

[0044] Whenever used in this specification, radial position r1 and relative refractive index Δ1 or Δ1(r) refer to the core region, radial position r2 and relative refractive index Δ2 or Δ2(r) refer to the offset cladding region, radial position r3 and relative refractive index Δ3 or Δ3(r) refer to the trench cladding region, radial position r4 and relative refractive index Δ4 or Δ4(r) refer to the outer cladding region, radial position r5 refer to the primary coating, radial position r6 refer to the secondary coating, and radial position r7 refer to the optional tertiary coating.

[0045] The relative refractive index Δ1(r) is the maximum value Δ 1max and the minimum value Δ 1min The relative refractive index Δ2(r) has a maximum value Δ 2max and the minimum value Δ 2min The relative refractive index Δ3(r) has a maximum value Δ 3max and the minimum value Δ 3min The relative refractive index Δ4(r) has a maximum value Δ 4max and the minimum value Δ 4minIt has. In embodiments where the relative refractive index is constant or substantially constant over a region, the maximum and minimum values of the relative refractive index are equal or substantially equal. Unless otherwise specified, when a single value is reported for the relative refractive index of a region, the single value corresponds to the average value of the region.

[0046] The core region is the central region of the glass fiber and is substantially cylindrical in shape, and it is understood that the surrounding optional offset cladding region, surrounding trench cladding region, surrounding outer cladding region, surrounding primary coating, surrounding secondary coating, and surrounding tertiary coating are substantially annular in shape. The annular regions can be characterized in terms of inner and outer radii. The radial positions r1, r2, r3, r4, r5, r6, and r7 herein refer to the outermost radius of the core, offset cladding region, trench cladding region, outer cladding region, primary coating, secondary coating, and tertiary coating, respectively. The radius r4 corresponds to the outer radius of the glass fiber. The outer radius of the optical fiber is the outer radius of the outermost coating surrounding the glass fiber. The tertiary coating is optional. When the tertiary coating is present, the radius r7 corresponds to the outer radius of the optical fiber. When the tertiary coating is absent and the secondary coating is present, the radius r6 corresponds to the outer radius of the optical fiber. In some embodiments, the core region has an inner core region with a radius r a inside r1 and an outer core region that surrounds the inner core region and has a radius r1 that is directly adjacent to the inner core region, and is a segmented core region.

[0047] When two regions are immediately adjacent to one another, the outer radius of the inner of the two regions matches the inner radius of the outer of the two regions. In one embodiment, for example, the glass fiber includes a trench cladding region surrounded by and immediately adjacent to the outer cladding region. In such an embodiment, radius r3 corresponds to the outer radius of the trench cladding region and the inner radius of the outer cladding region. In an embodiment where the relative refractive index profile includes a trench cladding region immediately adjacent to the core, radial position r1 corresponds to the outer radius of the core and the inner radius of the trench cladding region. The thickness (also referred to herein as width) of a region is the difference between the outer and inner radii of the region.

[0048] The following terms apply to embodiments in which the relative refractive index profile includes an offset cladding region surrounding and immediately adjacent to the core region, a trench cladding region surrounding and immediately adjacent to the offset cladding region, an outer cladding region surrounding and immediately adjacent to the trench cladding region, a primary coating surrounding and immediately adjacent to the outer cladding region, and a secondary coating surrounding the primary coating and immediately adjacent to the primary coating. The difference between radial position r2 and radial position r1 is referred to herein as the thickness of the offset cladding region. The difference between radial position r3 and radial position r2 is referred to herein as the thickness of the trench cladding region. The difference between radial position r4 and radial position r3 is referred to herein as the thickness of the outer cladding region. The difference between radial position r5 and radial position r4 is referred to herein as the thickness of the outer cladding region. The difference between radial location r6 and radial location r5 is referred to herein as the thickness of the secondary coating.

[0049] The following terminology applies to embodiments in which the trench cladding region is immediately adjacent to the core region and the outer cladding region is immediately adjacent to the trench cladding region. The difference between radial location r3 and radial location r1 is referred to herein as the thickness of the trench cladding region. The difference between radial location r4 and radial location r3 is referred to herein as the thickness of the outer cladding region. The difference between radial location r5 and radial location r4 is referred to herein as the thickness of the primary coating. The difference between radial location r6 and radial location r5 is referred to herein as the thickness of the secondary coating.

[0050] As described further below, the relative refractive indices of the core region, offset cladding region, trench cladding region, and outer cladding region are different. Each region is formed from doped or undoped silica glass. Variations in refractive index relative to undoped silica glass are achieved by incorporating updopants or downdopants at levels designed to provide a target refractive index or refractive index profile using techniques known to those skilled in the art. Updopants are dopants that increase the refractive index of the glass compared to the undoped glass composition. Downdopants are dopants that decrease the refractive index of the glass compared to the undoped glass composition. In one embodiment, the undoped glass is pure silica glass. When the undoped glass is pure silica glass, updopants include Cl, Br, Ge, Al, P, Ti, Zr, Nb, and Ta, and downdopants include F and B. Regions of constant refractive index may be formed by either no doping or by uniform doping. Regions of variable refractive index are formed through non-uniform spatial distribution of dopants and / or through the incorporation of different dopants in different regions. The refractive index varies approximately linearly with the concentration of the updopant or downdopant. For example, every 1 wt. % Cl as a dopant in silica glass increases the relative refractive index by about 0.083%, and every 1 wt. % F as a dopant in silica glass decreases the relative refractive index by about 0.32%. Alkali dopants have a negligible effect on the relative refractive index of silica glass.

[0051] The coating formed on the glass fiber is formed from a curable coating composition. The curable coating composition includes one or more curable components. As used herein, the term "curable" is intended to mean that the component contains one or more curable functional groups capable of forming a covalent bond, which is responsible for bonding the component to itself or to other components of the coating composition, when exposed to a suitable source of curing energy. The product obtained by curing a curable coating composition is referred to herein as the cured product of the composition. The cured product is preferably a polymer. The curing process is energy-induced. The form of energy includes radiation or thermal energy. In preferred embodiments, curing occurs with radiation, where radiation refers to electromagnetic radiation. Radiation-induced curing is referred to herein as radiation curing or photocuring. A radiation-curable component is one that can be induced to undergo a curing reaction when exposed to radiation of a suitable wavelength at a suitable intensity for a sufficient length of time. Suitable wavelengths include those in the infrared, visible, or ultraviolet portions of the electromagnetic spectrum. The radiation curing reaction occurs in the presence of a photoinitiator. The radiation-curable component may also be heat-curable. Similarly, a heat-curable component is one that can be induced to undergo a curing reaction when exposed to thermal energy of sufficient intensity for a sufficient length of time. The heat-curable component may also be radiation-curable.

[0052] The curable component includes one or more curable functional groups. A curable component having only one curable functional group is referred to herein as a monofunctional curable component. A curable component having two or more curable functional groups is referred to herein as a multifunctional curable component. A multifunctional curable component includes two or more functional groups capable of forming covalent bonds during the curing process, and can introduce crosslinks into the polymer network formed during the curing process. A multifunctional curable component may also be referred to herein as a "crosslinker" or "curable crosslinker." Curable components include curable monomers and curable oligomers. Examples of functional groups involved in the formation of covalent bonds during the curing process are identified hereinafter.

[0053] The term "(meth)acrylate" means methacrylate, acrylate, or a combination of methacrylate and acrylate.

[0054] Reference will now be made in detail to the exemplary embodiments of the present description.

[0055] This specification relates to glass and optical fibers having low attenuation, low microbending loss, low macrobending loss at bend diameters greater than and less than 40 mm, and low nonlinear loss. Bending diameters greater than and less than 40 mm are common in optical fiber deployment environments. Achieving optical fibers that exhibit low macrobending loss at both large and small bend diameters has proven difficult. Optical fibers are typically customized for specific bend diameters, and optimizing bend loss at a specific bend diameter compromises bend loss at other bend diameters. A typical prior art approach to minimizing macrobending loss at multiple bend diameters is to reduce the effective area of ​​the optical fiber. However, this approach leads to higher nonlinear loss, thereby limiting the signal power and reach of the optical fiber.

[0056] As described herein, optical macrobend losses can be mitigated across a range of bend diameters through appropriate design of the optical fiber's refractive index profile. In particular, the inclusion of a trench cladding region between the core and cladding regions reduces macrobend losses. The trench cladding region disclosed herein is designed to reduce macrobend losses at bend diameters greater than 35 mm while maintaining low macrobend losses at bend diameters less than 35 mm. Optical fibers commonly used in terrestrial systems are optimized to minimize macrobend losses at small bend diameters (35 mm or less). However, there is an increasing need for more versatile optical fibers that can be deployed with minimal macrobend losses in environments with configurations requiring either small or large bend diameters (greater than 35 mm). However, it has been determined that optical fibers designed to minimize macrobend losses at small bend diameters exhibit high macrobend losses at large bend diameters.

[0057] The relative refractive index profile disclosed herein includes a trench cladding region that minimizes macrobend losses at bend diameters greater than 35 mm, while maintaining low macrobend losses at bend diameters of 35 mm or less. The radial position, thickness, and trench volume of the trench cladding region are designed to provide low macrobend losses in both large and small diameter bend configurations. In addition to low macrobend losses, the optical fiber is characterized by low attenuation and a sufficiently high effective area to minimize nonlinear losses at moderate optical signal powers.

[0058] One embodiment relates to an optical fiber. The optical fiber includes a glass fiber surrounded by a coating. An example of an optical fiber is shown in a schematic cross-section in Figure 1. The optical fiber 10 includes a glass fiber 11 surrounded by a primary coating 16 and a secondary coating 18. Further description of the glass fiber 11, the primary coating 16, and the secondary coating 18 is provided below.

[0059] FIG. 2 illustrates an optical fiber ribbon 30. The ribbon 30 includes a plurality of optical fibers 20 and a matrix 32 encapsulating the plurality of optical fibers. The optical fibers 20 include a core region, a cladding region, a primary coating, and a secondary coating, as described above. The optical fibers 20 may also include a tertiary coating, as described above. The secondary coating may include a pigment. The optical fibers 20 are aligned with one another in a substantially planar and parallel relationship. The optical fibers in the optical fiber ribbon are encapsulated by the ribbon matrix 32 in any known configuration (e.g., edge-bonded ribbon, thin-encapsulated ribbon, thick-encapsulated ribbon, or multi-layer ribbon) by conventional methods of fabricating optical fiber ribbons. In FIG. 2, the optical fiber ribbon 30 contains 12 optical fibers 20; however, it will be apparent to one skilled in the art that any number of optical fibers 20 (e.g., two or more) may be used to form the optical fiber ribbon 30 arranged for a particular use. The ribbon matrix 32 can be formed from the same composition used to prepare the secondary coating, or the ribbon matrix 32 can be formed from a different composition that is compatible with the use.

[0060] FIG. 3 illustrates an example fiber optic cable 40. The cable 40 includes multiple optical fibers 20 surrounded by a jacket 42. The optical fibers 20 may be tightly or loosely packed within a conduit surrounded by the inner surface 44 of the jacket 42. The number of fibers disposed within the jacket 42 is referred to as the "fiber count" of the fiber optic cable 40. The jacket 42 is formed from an extruded polymer material and may include multiple concentric layers of polymer or other materials. The fiber optic cable 40 may include one or more strength members (not shown) embedded within the jacket 42 or disposed within a conduit defined by the inner surface 44. The strength members include fibers or rods that are stiffer than the jacket 42. The strength members may be made of metal, braided steel, glass-reinforced plastic, fiberglass, or other suitable materials. The fiber optic cable 40 may include other layers (e.g., armor layers, moisture barriers, ripcords, etc.) surrounded by the jacket 42. The fiber optic cable 40 may have a stranded, loose-tube core, or other fiber optic cable configuration.

[0061] Glass Fiber. The optical fiber disclosed herein includes a glass fiber having a core region, a cladding region surrounding the core region, and a coating surrounding the cladding region. The core region and the cladding region are glass. As is well known to those skilled in the art, the glass fiber 11 includes a core region 12 and a cladding region 14. The core region 12 has a higher refractive index than the cladding region 14, and the glass fiber 11 functions as a waveguide.

[0062] In many applications, the core and cladding regions have a distinct core-cladding boundary. Alternatively, the core and cladding regions may lack a distinct boundary. One type of fiber is a stepped index fiber. Another type of fiber is a gradient index fiber, which has a core region with a refractive index that varies with distance from the center of the fiber. An example of a gradient index fiber is a fiber having a core region with a relative refractive index profile having an α profile defined by equation (3) above.

[0063] Schematic cross-sectional views of optical fibers are shown in Figures 4A and 4B. In Figure 4A, optical fiber 46 includes a core region 48, a cladding region 50, a primary coating 56, and a secondary coating 58. Cladding region 50 includes a trench cladding region 53 and an outer cladding region 55. In Figure 4B, optical fiber 46 includes a core region 48, a cladding region 50, a primary coating 56, and a secondary coating 58. Cladding region 50 includes an offset cladding region 51, a trench cladding region 53, and an outer cladding region 55.

[0064] In one embodiment (e.g., FIG. 4A), an optical fiber includes a trench cladding region surrounding a core, an outer cladding region surrounding the trench cladding region, a primary coating surrounding the outer cladding region, and a secondary coating surrounding the primary coating. The trench cladding region is directly adjacent to the core region, the outer cladding region is directly adjacent to the trench cladding region, the primary coating is directly adjacent to the outer cladding region, and the secondary coating is directly adjacent to the primary coating. A tertiary layer (e.g., an ink layer) optionally surrounds or is directly adjacent to the secondary coating in the foregoing embodiment.

[0065] In another embodiment (e.g., FIG. 4B), an optical fiber includes an offset cladding region surrounding the core, a trench cladding region surrounding the offset cladding region, an outer cladding region surrounding the trench cladding region, a primary coating surrounding the outer cladding region, and a secondary coating surrounding the primary coating. The offset cladding region is directly adjacent to the core region, the trench cladding region is directly adjacent to the offset cladding region, the outer cladding region is directly adjacent to the trench cladding region, the primary coating is directly adjacent to the outer cladding region, and the secondary coating is directly adjacent to the primary coating. A tertiary layer (e.g., an ink layer) optionally surrounds or is directly adjacent to the secondary coating in the previous embodiment.

[0066] A typical schematic relative refractive index profile of a glass fiber is shown in Figures 5A and 5B. Figure 5A shows the relationship between the outer radius r1 and the maximum relative refractive index Δ 1max 5B shows a gradient refractive index profile for a glass fiber 60 having a core region (1) with a relative refractive index Δ1 having a radius r1 of 1.5, a trench cladding region (3) extending from radial location r1 to radial location r3 and having a relative refractive index Δ3, and an outer cladding region (4) extending from radial location r3 to radial location r4 and having a relative refractive index Δ4. 1max 1 illustrates a gradient refractive index profile for glass fiber 60 having a core region (1) having a relative refractive index Δ1 having a refractive index of Δ2, an offset cladding region (2) extending from radial location r1 to radial location r2 and having a relative refractive index Δ2, a trench cladding region (3) extending from radial location r2 to radial location r3 and having a relative refractive index Δ3, and an outer cladding region (4) extending from radial location r3 to radial location r4 and having a relative refractive index Δ4.

[0067] In the profiles of Figures 5A and 5B, the trench cladding region (3) has a constant or average relative refractive index Δ3 that is less than the relative refractive index Δ4 of the outer cladding region (4). The core region (1) has the highest average relative refractive index and the highest maximum relative refractive index within the profile. The core region (1) may include a lower refractive index region at or near the centerline (known in the art as a "centerline dip") (not shown in Figures 5A and 5B, but present in the exemplary profiles described below).

[0068] In the embodiment shown in Figures 5A and 5B, the core region (1) of the glass fiber has a relative refractive index represented by an α profile. The radial position r0 (Δ 1max ) corresponds to the centerline of the fiber (r = 0), and the radial position r of the α profile zcorresponds to the core radius r1. In embodiments with a centerline dip, the radial position r0 is slightly offset from the centerline of the fiber (not shown). In other embodiments, the core region (1) shown in Figures 5A and 5B has a relative refractive index profile that is a stepped index instead of an α profile. In still other embodiments, the core region (1) has a relative refractive index profile that is not defined by either an α profile or a stepped refractive index profile. In some embodiments, the relative refractive index Δ1 decreases continuously radially away from the centerline. In other embodiments, the relative refractive index Δ1 varies over several radial positions between the centerline and r1 and includes a constant or nearly constant value over other radial positions between the centerline and r1.

[0069] In Figure 5A, the transition region 62 from the core region (1) to the trench cladding region (3) and the transition region 64 from the trench cladding region (3) to the outer cladding region (4) are shown as step-like changes. In Figure 5B, the transition region 62 from the offset cladding region (2) to the trench cladding region (3) and the transition region 64 from the trench cladding region (3) to the outer cladding region (4) are shown as step-like changes. It should be understood that the step-like changes are idealized, and that the transition regions 62 and 64 may not actually be exactly vertical. Instead, the transition regions 62 and / or 64 may have a slope or curve. When transition region 62 and / or transition region 64 are non-vertical, the inner radius (r1 or r2) of trench cladding region (3) corresponds to the radial location of the minimum relative refractive index of transition region 62, and the outer radius (r3) of trench cladding region (3) corresponds to the radial location of the maximum relative refractive index of transition region 64 (FIGS. 5C and 5D). For purposes of this disclosure, Δ 3min and Δ 3max The value of is determined for the portion of the trench cladding region (3) excluding the transition region 64.

[0070] The relative order of the relative refractive indices Δ1, Δ3, and Δ4 in the relative refractive index profiles shown in FIGS. 5A and 5B is determined by the condition Δ 1max >Δ4>Δ3.

[0071] The core region comprises silica glass. The silica glass of the core region can be undoped, updoped, and / or downdoped. In one embodiment, the silica glass of the core region is Ge-free, i.e., the core region comprises silica glass lacking Ge. In another embodiment, the core region comprises silica glass doped with germanium dioxide (GeO). Updoped silica glass embodiments include silica glass doped with alkali metal oxides (e.g., NaO, KO, LiO, CsO, or RbO). Downdoped silica glass includes silica glass doped with F. In some embodiments, the core region is co-doped with alkali metal oxides and fluorine. The concentration of KO in the core, expressed as the amount of K, is in the range of 10 ppm to 200 ppm, or 20 ppm to 150 ppm, or 30 ppm to 100 ppm, where ppm refers to parts per million by weight. The alkali metal oxide other than K2O is present in an amount corresponding to an equimolar amount of K2O, as determined from the amount of K shown above.

[0072] In some embodiments, the core region comprises updopants and downdopants, where the concentration of the updopants is highest at the centerline (r=0) (in embodiments without a centerline dip) or near the centerline (r=0) (in embodiments with a centerline dip) and lowest at radius r1, and the concentration of the downdopants is lowest at the centerline (r=0) and highest at radius r1. In such embodiments, the relative refractive index Δ1 can have a positive value near the centerline (r=0) and decrease to a negative value at radius r1.

[0073] In one embodiment, the core region has a radius r surrounded by an outer core region having a radius r1. awherein the inner core region comprises an up-doped silica glass, an alkali-doped silica glass, or an undoped silica glass, and has a maximum relative refractive index Δ 1max and the outer core region comprises down-doped silica glass and has a minimum negative relative refractive index Δ 1min where Δ 1max >Δ 1min The up-doped silica glass of the inner core region includes an up-dopant or a combination of an up-dopant and a down-dopant. The alkali-doped silica glass of the inner core region includes an alkali dopant or a combination of an alkali dopant and a down-dopant. In embodiments where the inner core region includes a combination of an up-dopant (or alkali metal oxide dopant) and a down-dopant, the relative concentrations of the up-dopant (or alkali metal oxide dopant) and the down-dopant are such that the maximum relative refractive index Δ 1max In embodiments where the outer core region includes a combination of updopants (or alkali metal oxide dopants) and downdopants, the relative concentrations of the updopants (or alkali metal oxide dopants) and downdopants are adjusted to provide a relative refractive index Δ 1min In one embodiment, the inner core region is silica glass doped with an alkali metal oxide and the outer core region is silica glass doped with F. In another embodiment, the inner core region is silica glass doped with an alkali metal oxide and the outer core region is silica glass doped with F and Cl.

[0074] In embodiments with segmented cores, Δ (as well as Δ 1max and Δ 1min ) refers to the entire core region including the inner core region and the outer core region, r1 corresponds to the outer radius of the outer core region, and r a corresponds to the outer radius of the inner core region. The boundary between the inner and outer core regions is at the radial position r a occurs where ra It is r1. In an embodiment having a core region with a center line dip, the core region increases from a certain value at r = 0 to a maximum value Δ at r a and then decreases to a minimum value Δ at a radial position greater than r 1max and less than or equal to r1, having a relative refractive index that forms a segmented core region.

[0075] In some embodiments, the relative refractive index of the core region of the glass fiber is represented by an α-profile having an α value within the range of 1.5 to 10, or within the range of 1.7 to 8.0, or within the range of 1.8 to 6.0, or within the range of 1.9 to 5.0, or within the range of 1.95 to 4.5, or within the range of 2.0 to 4.0, or within the range of 10 to 100, or within the range of 11 to 40, or within the range of 12 to 30. As the value of α increases, the relative refractive profile approximates a stepped refractive index profile. In some embodiments having a segmented core region, either or both of the inner core region and the outer core region have a relative refractive index represented by an α-profile having an α value described herein.

[0076] The outer radius r1 of the core region is within the range of 3.5 μm to 10.0 μm, or within the range of 5.5 μm to 9.0 μm, or within the range of 3.5 μm to 8.5 μm, or within the range of 4.0 μm to 8.0 μm. In some embodiments, the core region includes a segmented core region having a portion with a constant or substantially constant relative refractive index, where the portion has a radial width within the range of at least 1.0 μm, or at least 2.0 μm, or at least 3.0 μm, or at least 4.0 μm, or within the range of 1.0 μm to 6.0 μm, or within the range of 2.0 μm to 5.5 μm, or within the range of 3.0 μm to 5.0 μm. In an embodiment, the portion of the segmented core region having a constant or substantially constant relative refractive index is the outer core region, and Δ 1min ​​​​​​​​In some embodiments, the core region includes a segmented core region having a relative refractive index that decreases with increasing radius, where the segment has a radial width of at least 1.0 μm, or at least 2.0 μm, or at least 3.0 μm, or at least 4.0 μm, or in the range of 1.0 μm to 6.0 μm, or in the range of 2.0 μm to 5.5 μm, or in the range of 3.0 μm to 5.0 μm. In some embodiments, the decrease in relative refractive index with increasing radius occurs at a constant or nearly constant slope, where slope refers to the amount of decrease in relative refractive index per unit increase in radial position. In embodiments, the portion of the segmented core region whose relative refractive index decreases with increasing radial position is the outer core region. In embodiments having a segmented core region, the inner core region has a radius r of 1.0 μm, or at least 2.0 μm, or at least 3.0 μm, or at least 4.0 μm, or in the range of 1.0 μm to 6.0 μm, or in the range of 2.0 μm to 5.5 μm, or in the range of 3.0 μm to 5.0 μm. In some embodiments, the decrease in relative refractive index with increasing radius occurs at a constant or nearly constant slope, where slope refers to the amount of decrease in relative refractive index per unit increase in radial position. In embodiments having a segmented core region, the inner core region has a radius r of 1.0 μm. a is in the range of 0.5 μm to 4.0 μm, or in the range of 0.5 μm to 3.5 μm, or in the range of 1.0 μm to 3.0 μm, or in the range of 1.5 μm to 2.5 μm.

[0077] The relative refractive index of the core region, Δ1 or Δ 1max is in the range of -0.05% to 0.05%, or in the range of -0.04% to 0.04%, or in the range of -0.03% to 0.03%, or in the range of -0.02% to 0.02%, or in the range of -0.01% to 0.01%. 1min is within the range of -0.40% to -0.20%, or within the range of -0.35% to -0.25%. 1max ~Δ 1min is greater than 0.20%, or greater than 0.25%, or greater than 0.30%, or less than 0.40%, or less than 0.35%, or within the range of 0.20% to 0.40%, or within the range of 0.25% to 0.35%.

[0078] In embodiments with segmented core regions, the relative refractive index of the inner core region, Δ or Δ 1max is in the range of -0.05% to 0.05%, or in the range of -0.03% to 0.03%, or in the range of -0.01% to 0.01%.1min is within the range of -0.40% to -0.20%, or within the range of -0.35% to -0.25%. 1max ~Δ 1min is greater than 0.20%, or greater than 0.25%, or greater than 0.30%, or less than 0.40%, or less than 0.35%, or within the range of 0.20% to 0.40%, or within the range of 0.25% to 0.35%.

[0079] In some embodiments, the relative refractive index of the core region or inner core region is Δ 1max is represented by a step-like refractive index profile with constant or nearly constant values ​​corresponding to

[0080] In some embodiments, the cladding includes an offset cladding region immediately adjacent to the core region and a trench cladding region immediately adjacent to the offset cladding region. The offset cladding region has an inner radius r1 and an outer radius r2 as defined above. The radius r2 of the offset cladding region is in the range of 3.5 μm to 13.0 μm, or in the range of 4.0 μm to 11.0 μm, or in the range of 4.5 μm to 9.0 μm. The thickness r2 to r1 of the offset cladding region is greater than 0.0 μm and less than 4.0 μm, or in the range of 0.1 μm to 4.0 μm, or in the range of 0.5 μm to 4.0 μm, or in the range of 1.0 μm to 3.5 μm. The relative refractive index Δ2 of the offset cladding region is Δ 1min or less and Δ3 or more, or Δ 1min or less and Δ4 or more.

[0081] The trench cladding region includes a down-doped silica glass. A preferred down-dopant is F (fluorine). The concentration of F (fluorine) is in the range of 0.5 wt % to 2.0 wt %, or in the range of 0.6 wt % to 1.5 wt %, or in the range of 0.7 wt % to 1.2 wt %.

[0082] The relative refractive index of the trench cladding region, Δ3 or Δ 3minis within the range of -0.20% to -0.50%, or within the range of -0.25% to -0.45%, or within the range of -0.30% to -0.40%, or within the range of -0.28% to -0.38%. The relative refractive index Δ3 is preferably constant or approximately constant. Δ 1max and Δ3 (or Δ 1max and Δ 3min or the difference between Δ1 and Δ3, or the difference between Δ1 and Δ 3min and ) is greater than 0.20%, or greater than 0.25%, or greater than 0.30%, or greater than 0.35%, or in the range of 0.20% to 0.45%, or in the range of 0.25% to 0.40%. In some embodiments, the relative refractive index Δ3 of the trench cladding region is constant or nearly constant. In other embodiments, the relative refractive index Δ3 of the trench cladding region is graded, where the grade is constant or variable over the radial extent of the trench cladding region. In some embodiments, the relative refractive index profile of the trench cladding region has a triangular shape.

[0083] The inner radius of the trench cladding region is r1 (in embodiments without an offset cladding region) or r2 (in embodiments with an offset cladding region) and has the value specified above. The outer radius of the trench cladding region r3 is in the range of 12.0 μm to 22.0 μm, or in the range of 13.0 μm to 22.0 μm, or in the range of 14.0 μm to 20.0 μm, or in the range of 15.0 μm to 20.0 μm, or in the range of 15.0 μm to 19.0 μm. The thickness of the trench cladding region r3 to r1 (in embodiments without an offset cladding region) or r3 to r2 (in embodiments with an offset cladding region) is less than 16.0 μm, or less than 14.0 μm, or less than 12.0 μm, or less than 10.0 μm, or in the range of 6.0 μm to 16.0 μm, or in the range of 7.0 μm to 14.0 μm, or in the range of 8.0 μm to 12.0 μm.

[0084] The trench cladding area is 24% μm 2 Less than or 20% μm 2 Less than or equal to 18% μm2 Less than or 16% μm 2 Less than or equal to 14% μm 2 Less than or 12% μm 2 Less than or 4% μm 2 ~24%μm 2 Within the range of 6%μm 2 ~20%μm 2 Within the range of 8% μm 2 ~18%μm 2 Within the range of 10%μm 2 ~16%μm 2 The trench volume can be controlled by varying the thickness of the trench cladding region, the relative refractive index of the trench cladding region, and / or the difference between the relative refractive index of the outer cladding region and the relative refractive index of the trench cladding region.

[0085] The relative refractive index of the outer cladding region, Δ4 or Δ 4max is within the range of -0.45% to -0.15%, or within the range of -0.40% to -0.20%, or within the range of -0.35% to -0.25%, or within the range of -0.33% to -0.23%. The relative refractive index Δ4 is ​​preferably constant or approximately constant. The difference Δ4 to Δ3 (or the difference Δ4 to Δ 3min , or the difference Δ 4max ~Δ3, or the difference Δ 4max ~Δ 3min ) is less than 0.15%, or less than 0.10%, or more than 0.04%, or more than 0.07%, or in the range of 0.04% to 0.15%, or in the range of 0.07% to 0.13%.

[0086] The inner radius of the outer cladding region is r3 and has the value specified above. The outer radius of the outer cladding region r4 is in the range of 60.0 μm to 65.0 μm, or in the range of 61.0 μm to 64.0 μm, or in the range of 62.0 μm to 63.0 μm, or about 62.5 μm. The thicknesses of the outer cladding regions r4 to r3 are in the range of 20.0 μm to 50.0 μm, or in the range of 25.0 μm to 45.0 μm, or in the range of 30.0 μm to 40.0 μm.

[0087] In one embodiment, the core region of the relative refractive index profile has an outer radius r such that r a <is r1 a The segmented core region has a radius r1 corresponding to the outer radius of the outer core region, together with the inner core region having an outer radius of r<r1. In one embodiment, each of the inner core region and the outer core region has a relative refractive index profile represented by an α-profile. In one embodiment, the inner core region has an α value of less than 20, or less than 10, or less than 5.0, or less than 3.0, or less than 2.0, or within the range of 1.0 to 20, or within the range of 1.5 to 10, or within the range of 1.7 to 5.0, or within the range of 1.8 to 3.0, and the outer core region has an α value of greater than 10, or greater than 20, or greater than 50, or greater than 100, or greater than 150, or greater than 200, or within the range of 20 to 300, or within the range of 50 to 250, or within the range of 100 to 200. In another embodiment, the inner core region has a relative refractive index profile represented by an α-profile, and the outer core region has a relative refractive index profile represented by a stepped refractive index profile. In another embodiment, the inner core region has a relative refractive index profile represented by an α-profile, and the outer core region has a relative refractive index profile represented by a rounded stepped refractive index profile.

[0088] In one embodiment, the inner core region is alkali-doped silica, and the outer core region is halogen-doped silica. The halogen-doped silica includes silica doped with one or more of Cl, F, and Br. In one embodiment, the inner core region is silica doped with K2O, and the outer core region is doped with F or a combination of F and Cl.

[0089] In an embodiment where each of the inner core region and the outer core region has a relative refractive index profile represented by an α-profile, the radius r a ​​​​​​​​2 is determined by minimizing f(r i ) is the α profile function of the inner core region, and g(r j ) is the α profile function of the outer core region, and g(r a ) is r j =r a g(r j ) and Δ(r i ) is the measured relative refractive index profile of the inner core region, and Δ(r j ) is the measured relative refractive index profile of the outer core region, and the index “i” is the refractive index at the radial position r of the inner core region. i The index "j" is the radial position r of the outer core region. j 0 per <r i <r a and r a ≦r j ≦r b where the index "a" is the value of the index "i" and r i =r a where the exponent "b" is the value of the exponent "j" and the j =r1.

[0090] Optical Fiber Coatings. The transmittance of light through an optical fiber depends largely on the properties of the coating applied to the glass fiber. The coating typically includes a primary coating and a secondary coating, where the secondary coating surrounds the primary coating and the primary coating is in contact with the glass fiber (which includes a central core region surrounded by a cladding region). The secondary coating is made of a harder material (higher Young's modulus (e.g., greater than 1400 MPa)) than the primary coating and is designed to protect the glass fiber from damage caused by abrasion or external forces generated during processing, handling, and installation of the optical fiber. The primary coating is made of a softer material (lower Young's modulus (e.g., less than 1 MPa)) than the secondary coating and is designed to buffer or dissipate stresses resulting from forces applied to the outer surface of the secondary coating. Stress dissipation within the primary coating attenuates the stresses and minimizes the stresses that reach the glass fiber. The primary coating is particularly important in dissipating stresses caused by microbending that the optical fiber experiences when deployed in a cable. Microbending stresses cause localized perturbations in the refractive index profile of the glass fiber, so it is necessary to minimize the microbending stresses transmitted to the glass fiber. The localized refractive index perturbations result in intensity losses for light transmitted through the glass fiber. By dissipating stresses, the primary coating minimizes microbending-induced strength losses.

[0091] The primary coating 16 preferably has a higher refractive index than the cladding region of the glass fiber to allow stray optical signals to be removed from the core region. The primary coating must maintain adequate adhesion to the glass fiber during thermal and hydrolytic aging, but can also be stripped from the glass fiber for splicing purposes.

[0092] The primary and secondary coatings are typically formed by applying a curable coating composition to the glass fiber as a viscous liquid and curing it. The optical fiber may also include a tertiary coating (not shown) surrounding the secondary coating. The tertiary coating may include pigments, inks, or other colorants to mark the optical fiber for identification purposes and typically has a Young's modulus similar to that of the secondary coating.

[0093] Primary coating composition. The primary coating is the cured product of a curable primary coating composition. The curable primary coating composition provides a primary coating for an optical fiber that exhibits a low Young's modulus, low pull-out force, and strong cohesion. The curable primary coating composition further enables the formation of a primary coating that is characterized by clean strippability and high resistance to defect formation during stripping operations. The low pull-out force facilitates clean stripping of the primary coating with minimal residue, and the strong cohesion prevents the initiation and propagation of defects in the primary coating when it is subjected to stripping forces.

[0094] The primary coating is the cured product of a radiation-curable primary coating composition comprising an oligomer, a monomer, a photoinitiator, and optionally additives. The following disclosure describes oligomers for the radiation-curable primary coating composition, a radiation-curable primary coating composition comprising at least one of the oligomers, a cured product of a radiation-curable primary coating composition comprising at least one of the oligomers, a glass fiber coated with a radiation-curable primary coating composition containing at least one of the oligomers, and a glass fiber coated with a cured product of a radiation-curable primary coating composition containing at least one of the oligomers.

[0095] The oligomer preferably comprises a polyetherurethane diacrylate compound or a combination of a polyetherurethane diacrylate compound and a diaddition compound. In one embodiment, the polyetherurethane diacrylate compound has a linear molecular structure. In one embodiment, the oligomer is formed from the reaction between a diisocyanate compound, a polyol compound, and a hydroxyacrylate compound, where the reaction produces a polyetherurethane diacrylate compound as a primary product (majority product) and a diaddition compound as a by-product (minority product). The reaction forms a urethane bond upon reaction of the isocyanate group of the diisocyanate compound with the alcohol group of the polyol. The hydroxyacrylate compound reacts to quench residual isocyanate groups present in the composition formed from the reaction of the diisocyanate compound and the polyol compound. As used herein, the term "quenching" refers to the conversion of an isocyanate group by chemical reaction with the hydroxyl group of the hydroxyacrylate compound. Quenching of residual isocyanate groups with a hydroxy acrylate compound converts terminal isocyanate groups to terminal acrylate groups.

[0096] The diisocyanate compound, hydroxyacrylate compound, and polyol are combined and reacted simultaneously or sequentially (in any order). In one embodiment, the oligomer is formed by reacting the diisocyanate compound with the hydroxyacrylate compound and then reacting the resulting product composition with a polyol. In another embodiment, the oligomer is formed by reacting the diisocyanate compound with the polyol compound and then reacting the resulting product composition with a hydroxyacrylate compound.

[0097] The oligomer is formed from the reaction of a diisocyanate compound, a hydroxyacrylate compound, and a polyol, wherein the molar ratio of the diisocyanate compound, the hydroxyacrylate compound, and the polyol in the reaction process is n:m:p. n, m, and p are referred to herein as the number of moles or the molar ratio of the diisocyanate, the hydroxyacrylate, and the polyol, respectively. The mole numbers n, m, and p are positive integers or positive non-integers. In an embodiment, when p is 2.0, n is in the range of 3.0 to 5.0, or in the range of 3.2 to 4.8, or in the range of 3.4 to 4.6, or in the range of 3.5 to 4.4, or in the range of 3.6 to 4.2, or in the range of 3.7 to 4.0, and m is in the range of 1.5 to 4.0, or in the range of 1.6 to 3.6, or in the range of 1.7 to 3.2, or in the range of 1.8 to 2.8, or in the range of 1.9 to 2.4. For values ​​of p other than 2.0, the molar ratio n:m:p is adjusted proportionately. For example, a molar ratio of n:m:p = 4.0:3.0:2.0 is equivalent to a molar ratio of n:m:p = 2.0:1.5:1.0.

[0098] The curable primary coating composition further comprises one or more monomers selected to be compatible with the oligomer, to control the viscosity of the primary coating composition to facilitate processing, and / or to influence the physical or chemical properties of the coating formed as a cured product of the primary coating composition. The monomers include radiation-curable monomers such as ethylenically unsaturated compounds, ethoxylated acrylates, ethoxylated alkylphenol monoacrylates, propylene oxide acrylate, n-propylene oxide acrylate, isopropylene oxide acrylate, monofunctional acrylates, monofunctional aliphatic epoxy acrylates, multifunctional acrylates, multifunctional aliphatic epoxy acrylates, and combinations thereof.

[0099] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers having one or more acrylate or methacrylate groups. Alkoxylated monomers contain one or more alkoxylene groups, where the alkoxylene group has the form -OR-, and R is a linear or branched alkylene group. Examples of alkoxylene groups include ethoxylene (-O-CH2-CH2-), n-propoxylene (-O-CH2-CH2-CH2-), isopropoxylene (-O-CH2-CH(CH3)-, or -O-CH(CH3)-CH2-), and the like. As used herein, the degree of alkoxylation refers to the number of alkoxylene groups in a monomer. In one embodiment, the alkoxylene groups are consecutively bonded in the monomer.

[0100] In some embodiments, the primary coating composition is R—R—O—(CH(CH)CH—O) q -C(O)CH=CH2 [where R4 and R5 are aliphatic, aromatic, or a mixture of both, and q=1 to 10], or R4-O-(CH(CH3)CH2-O) q Alkoxylated monomers of the form -C(O)CH=CH2, where C(O) is a carbonyl group, R1 is aliphatic or aromatic, and q=1-10.

[0101] In some embodiments, the monomer component of the primary coating composition comprises a multifunctional (meth)acrylate. Multifunctional ethylenically unsaturated monomers include multifunctional acrylate monomers and multifunctional methacrylate monomers. Multifunctional acrylates are acrylates having two or more polymerizable acrylate moieties per molecule or three or more polymerizable acrylate moieties per molecule.

[0102] In some embodiments, the primary coating composition comprises an N-vinyl amide monomer such as N-vinyl lactam, or N-vinyl pyrrolidinone, or N-vinyl caprolactam.

[0103] In addition to the curable monomer and oligomer, the curable primary coating composition also includes a polymerization initiator. The polymerization initiator facilitates initiation of the polymerization process involved in curing the coating composition to form the coating. Polymerization initiators include thermal initiators, chemical initiators, electron beam initiators, and photoinitiators. Photoinitiators include ketone-based photoinitiators and / or phosphine oxide photoinitiators. When used to cure the coating composition, the photoinitiator is present in an amount sufficient to allow rapid radiation cure.

[0104] The curable primary coating composition optionally contains one or more additives. Additives include adhesion promoters, strength additives, antioxidants, catalysts, stabilizers, optical brighteners, property-enhancing additives, amine synergists, waxes, lubricants, and / or slip agents. Some additives act to control the polymerization process, thereby affecting the physical properties (e.g., modulus, glass transition temperature) of the polymerization product formed from the coating composition. Other additives affect the integrity of the cured product of the primary coating composition (e.g., protecting against depolymerization or oxidative degradation).

[0105] Primary Coating - Characteristics. The radius r5 of the primary coating is 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or 70.0 μm or less, or 67.5 μm or less, or within the range of 65.0 μm to 90.0 μm, or within the range of 67.5 μm to 85.0 μm, or within the range of 70.0 μm to 80.0 μm.

[0106] To facilitate the reduction of the optical fiber diameter, it is preferable to minimize the thicknesses r5-r4 of the primary coating, which may be equal to or less than 30.0 μm, or equal to or less than 25.0 μm, or equal to or less than 20.0 μm, or equal to or less than 15.0 μm, or equal to or less than 10.0 μm, or within the range of 7.5 μm to 30.0 μm, or within the range of 10.0 μm to 27.5 μm, or within the range of 12.5 μm to 25.0 μm, or within the range of 15.0 μm to 30.0 μm, or within the range of 15.0 μm to 27.5 μm, or within the range of 15.0 μm to 25.0 μm, or within the range of 15.0 μm to 20.0 μm, or within the range of 7.5 μm to 12.5 μm.

[0107] In some embodiments, the optical fiber includes a glass fiber having a radius r4 in the range of 60.0 μm to 65.0 μm and a primary coating having a radius r5 of 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or in the range of 75.0 μm to 85.0 μm, or in the range of 77.5 μm to 82.5 μm.

[0108] In some embodiments, the optical fiber comprises a glass fiber having a radius r4 in the range of 60.0 μm to 65.0 μm and a primary coating having a thickness r5 to r4 of 30.0 μm or less, or 25.0 μm or less, or 20.0 μm or less, or in the range of 10.0 μm to 30.0 μm, or in the range of 12.5 μm to 27.5 μm, or in the range of 12.5 μm to 25.0 μm, or in the range of 15.0 μm to 30.0 μm, or in the range of 15.0 μm to 27.5 μm, or in the range of 15.0 μm to 20.0 μm.

[0109] To facilitate effective stress buffering and protection of the glass fiber, the primary coating preferably has a low Young's modulus and / or a low in-situ elastic modulus. The Young's modulus of the primary coating is 0.7 MPa or less, or 0.6 MPa or less, or 0.5 MPa or less, or 0.4 MPa or less, or in the range of 0.1 MPa to 0.7 MPa, or in the range of 0.3 MPa to 0.6 MPa. The in-situ elastic modulus of the primary coating is 0.30 MPa or less, or 0.25 MPa or less, or 0.20 MPa or less, or 0.15 MPa or less, or 0.10 MPa or less, or in the range of 0.05 MPa to 0.25 MPa, or in the range of 0.10 MPa to 0.20 MPa.

[0110] Secondary coating compositions. The secondary coating is a cured product of a curable secondary coating composition that includes a monomer, a photoinitiator, an optional oligomer, and optional additives. This disclosure describes optional oligomers for the radiation-curable secondary coating composition, radiation-curable secondary coating compositions, cured products of radiation-curable secondary coating compositions, optical fibers coated with radiation-curable secondary coating compositions, and optical fibers coated with cured products of radiation-curable secondary coating compositions.

[0111] The secondary coating is formed as the cured product of a radiation-curable secondary coating composition that includes a monomer component having one or more monomers. The monomers preferably include ethylenically unsaturated compounds. In one embodiment, the secondary coating is the radiation-cured product of a secondary coating composition that includes a urethane acrylate monomer.

[0112] The monomer contains a functional group that is a polymerizable group and / or a group that promotes or enables crosslinking. The monomer may be a monofunctional or polyfunctional monomer. In a combination of two or more monomers, the constituent monomers may be monofunctional, polyfunctional, or a combination of monofunctional and polyfunctional monomers. In one embodiment, the monomer component of the curable secondary coating composition comprises an ethylenically unsaturated monomer. Suitable functional groups for the ethylenically unsaturated monomer include, but are not limited to, (meth)acrylate, acrylamide, N-vinylamide, styrene, vinyl ether, vinyl ester, acid ester, and combinations thereof.

[0113] In one embodiment, the monomer component of the curable secondary coating composition comprises an ethylenically unsaturated monomer. The monomer comprises a functional group that is a polymerizable group and / or a group that promotes or enables crosslinking. The monomer is a monofunctional or polyfunctional monomer. In a combination of two or more monomers, the constituent monomers are monofunctional monomers, polyfunctional monomers, or a combination of monofunctional and polyfunctional monomers. Suitable functional groups for the ethylenically unsaturated monomer include, but are not limited to, (meth)acrylate, acrylamide, N-vinylamide, styrene, vinyl ether, vinyl ester, acid ester, and combinations thereof.

[0114] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers having one or more acrylate or methacrylate groups. Alkoxylated monomers include one or more alkoxylene groups, where the alkoxylene group has the form -OR-, and R is a linear or branched hydrocarbon. Examples of alkoxylene groups include ethoxylene (-O-CH2-CH2-), n-propoxylene (-O-CH2-CH2-CH2-), isopropoxylene (-O-CH2-CH(CH3)-), and the like. As used herein, the degree of alkoxylation refers to the number of alkoxylene groups in a monomer. In one embodiment, the alkoxylene groups are consecutively linked in the monomer.

[0115] Polyfunctional ethylenically unsaturated monomers for the curable secondary coating composition include, but are not limited to, alkoxylated bisphenol A diacrylates, such as ethoxylated bisphenol A diacrylate, where the degree of alkoxylation is 2 or greater. Monomer components of the secondary coating composition may include ethoxylated bisphenol A diacrylate having an ethoxylation degree ranging from 2 to about 30, or propoxylated bisphenol A diacrylate having a propoxylation degree of 2 or greater, for example, ranging from 2 to about 30, and methylolpropane polyacrylates with and without alkoxylation, such as ethoxylated trimethylolpropane triacrylate having an ethoxylation degree of 3 or greater.

[0116] The curable secondary coating composition also includes a photoinitiator and, optionally, additives such as antioxidant(s), optical brightener(s), amine synergist(s), tackifier(s), catalyst(s), carriers or surfactants, and stabilizers, as described above in connection with the curable primary coating composition.

[0117] Secondary Coating - Properties: Relevant properties of the secondary coating include radius, thickness, and Young's modulus.

[0118] The radius r6 of the secondary coating is 110.0 μm or less, or 105.0 μm or less, or 100.0 μm or less, or 95.0 μm or less, or 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or in the range of 75.0 μm to 110.0 μm, or in the range of 80.0 μm to 105.0 μm, or in the range of 85.0 μm to 100.0 μm.

[0119] To facilitate the reduction of the optical fiber diameter, it is preferable to minimize the thicknesses r6-r5 of the secondary coating, which may be equal to or less than 30.0 μm, or equal to or less than 25.0 μm, or equal to or less than 20.0 μm, or equal to or less than 15.0 μm, or equal to or less than 10.0 μm, or within the range of 7.5 μm to 30.0 μm, or within the range of 10.0 μm to 30.0 μm, or within the range of 10.0 μm to 20.0 μm, or within the range of 10.0 μm to 15.0 μm, or within the range of 12.5 μm to 27.5 μm, or within the range of 12.5 μm to 25.0 μm, or within the range of 12.5 μm to 22.5 μm, or within the range of 15.0 μm to 30.0 μm, or within the range of 15.0 μm to 27.5 μm, or within the range of 15.0 μm to 25.0 μm.

[0120] In some embodiments, the optical fiber includes a glass fiber having a radius r4 in the range of 60.0 μm to 65.0 μm, a primary coating having a radius r5 of 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or in the range of 75.0 μm to 85.0 μm, or in the range of 77.5 μm to 82.5 μm, and a secondary coating having a radius r6 of 110.0 μm or less, or 100.0 μm or less, or 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or 70.0 μm or less, or in the range of 70.0 μm to 110.0 μm, or in the range of 80.0 μm to 110.0 μm, or in the range of 90.0 μm to 105.0 μm, or in the range of 95.0 μm to 105.0 μm.

[0121] In some embodiments, the optical fiber is a glass fiber having a radius r4 in the range of 60.0 μm to 65.0 μm, and a glass fiber having a radius r5 of 30.0 μm or less, or 25.0 μm or less, or 20.0 μm or less, or 15.0 μm or less, or in the range of 10.0 μm to 30.0 μm, or in the range of 12.5 μm to 27.5 μm, or in the range of 12.5 μm to 25.0 μm, or in the range of 15.0 μm to 30.0 μm, or in the range of 15.0 μm to 27.5 μm, or in the range of 10.0 μm to 30.0 μm. and a secondary coating having a radius r6 of 110.0 μm or less, or 100.0 μm or less, or 90.0 μm or less, or 85.0 μm or less, or 80.0 μm or less, or 75.0 μm or less, or 70.0 μm or less, or in the range of 70.0 μm to 110.0 μm, or in the range of 72.5 μm to 100.0 μm, or in the range of 75.0 μm to 90.0 μm.

[0122] To facilitate protection of the glass fiber and primary coating from external stress and puncture, the secondary coating preferably has a high Young's modulus, such as 1400 MPa or more, 1800 MPa or more, 2200 MPa or more, or 2600 MPa or more, or in the range of 1400 MPa to 3000 MPa, or in the range of 1800 MPa to 2600 MPa.

[0123] Fiber Drawing Process. In a continuous optical fiber manufacturing process, a glass fiber is drawn from a heated preform and sized to the target diameter (typically 125 μm, corresponding to r4=62.5 μm). The heated preform is formed by soot deposition using a silica precursor and optional doped precursors. Soot deposition techniques include outside vapor deposition (OVD), vapor axial deposition (VAD), and plasma-enhanced chemical vapor deposition (PCVD). Silica precursors include SiCl4 and OMCTS (octamethylcyclotetrasiloxane). Alkali-doped precursors include alkali metal oxides. Fluorine-doped precursors include SiF4.

[0124] The glass fiber is then cooled and sent to a coating system that applies a liquid primary coating composition to the glass fiber. After the liquid primary coating composition is applied to the glass fiber, two process options are possible. In one process option (a wet-on-dry process), the liquid primary coating composition is cured to form a solidified primary coating, a liquid secondary coating composition is applied to the cured primary coating, and the liquid secondary coating composition is cured to form a solidified secondary coating. In the second process option (a wet-on-wet process), a liquid secondary coating composition is applied to the liquid primary coating composition, and both liquid coating compositions are cured simultaneously to provide solidified primary and secondary coatings. After the fiber exits the coating system, it is collected and stored at room temperature. Collecting the fiber typically involves winding the fiber onto a spool and storing the spool.

[0125] In some processes, the coating system further applies a tertiary coating composition to the secondary coating and cures the tertiary coating composition to form a solidified tertiary coating. Typically, the tertiary coating is an ink layer used to mark the fiber for identification purposes, and includes a pigment but otherwise has a similar composition to the secondary coating. The tertiary coating is applied to the secondary coating and cured. The secondary coating is typically cured when the tertiary coating is applied. The primary, secondary, and tertiary coating compositions can be applied and cured in a common continuous manufacturing process. Alternatively, the primary and secondary coating compositions are applied and cured in a common continuous manufacturing process, the coated fiber is collected, and the tertiary coating composition is applied and cured in a separate offline process to form the tertiary coating.

[0126] The wavelength of the curing radiation may be infrared, visible light, or ultraviolet (UV). Typical wavelengths include those in the range of 250 nm to 1000 nm, or 250 nm to 700 nm, or 250 nm to 450 nm, or 275 nm to 425 nm, or 300 nm to 400 nm, or 320 nm to 390 nm, or 330 nm to 380 nm, or 340 nm to 370 nm. Curing can be achieved with light sources including lamp sources (e.g., Hg lamps), LED sources (e.g., UV LEDs, visible light LEDs, or infrared LEDs), or laser sources.

[0127] Each of the primary, secondary, and tertiary compositions can be cured with any of the wavelengths and light sources mentioned above. The same wavelength or light source can be used to cure each of the primary, secondary, and tertiary compositions, or different wavelengths and / or different light sources can be used to cure the primary, secondary, and tertiary compositions. Curing of the primary, secondary, and tertiary compositions can be achieved with a single wavelength or a combination of two or more wavelengths.

[0128] To improve process efficiency, it is desirable to increase the draw speed of the fiber along the process path extending from the preform to the collection point. However, as the draw speed increases, the cure rate of the coating composition must also increase. The coating compositions disclosed herein are compatible with fiber draw processes operating at draw speeds greater than 10 m / s, or greater than 15 m / s, or greater than 20 m / s, or greater than 25 m / s, or greater than 30 m / s. [Example]

[0129] The following examples illustrate optical fibers having a trench cladding region configured to minimize macrobend and microbend losses. More specifically, the trench cladding region of the exemplary optical fiber has a relative refractive index, inner and outer radial position, thickness, and trench volume that promotes minimizing macrobend losses at bend diameters of 35 mm or less and greater than 35 mm, and minimizing microbend losses at 1550 nm.

[0130] Modeled and experimental examples are discussed. The experimental examples correspond to fabricated glass fibers. The core region of the experimental fiber was doped with potassium oxide, and the trench cladding region of the experimental fiber was doped with fluorine. The tests used to determine the macrobend and microbend losses of the experimental examples, as well as the relative refractive index profiles of the modeled and experimental examples, are described in further detail below.

[0131] Macrobending. Macrobending loss for the examples was determined using the mandrel wrap test specified in the Telecommunications Industry Association (TIA) standard TIA-455-62:FOTP-62 IEC-60793-1-47 Optical Fibers - Part 1-47: Measurement Methods and Test Procedures - Macrobending Loss. In a mandrel wrap test, the fiber is wrapped one or more times around a smooth, cylindrical mandrel with a specified diameter to determine the increase in attenuation at a specified wavelength due to bending. Mandrel wrap test attenuation is expressed in units of dB / turn, where dB refers to decibels and one turn refers to one rotation of the fiber around the mandrel. Macrobending loss at a wavelength of 1550 nm was determined for selected examples using mandrels with diameters of 32 mm, 40 mm, 50 mm, and 60 mm, as described below.

[0132] Microbending. Microbending loss for the example experiments was determined by the test described as Method A in Section 5.1 of the International Electrotechnical Commission Technical Report IEC TR62221 Measurement Methods - Microbending Sensitivity, using sandpaper (grade 40 micron, mineral Al2O3) as the fixed roughness material (see Section 4.5). For the test, 600 m to 700 m lengths of optical fiber were wound at a fixed winding tension around a drum with a 153 mm radius covered with sandpaper. As described below, microbending loss was determined for winding tensions of 30.0 g, 60.0 g, and 90.0 g, which correspond to winding forces of 0.196 g / mm, 0.392 g / mm, and 0.588 g / mm, respectively.

[0133] Modeling Examples. The relative refractive index profiles of modeling examples Ex1, Ex2, and Ex3 are shown in FIGS. 6A-6C, respectively. The relative refractive index profiles of the modeling examples include a bounded core region having an outer core region surrounding and directly adjacent to the inner core region, a trench cladding region surrounding and directly adjacent to the outer core region, and an outer cladding region surrounding and directly adjacent to the trench cladding region. In the modeling examples, the transition region between the core region and the trench cladding region is vertical, and the transition region between the trench cladding region and the outer cladding region is vertical. The relative refractive index Δ3 within the trench cladding region of the modeling examples is graded and has an approximately triangular shape.

[0134] The parameters of the relative refractive index profiles of modeling examples Ex1, Ex2, and Ex3 are given in Tables 1 and 2. The value Δ1 corresponds to the average relative refractive index of the delimited core region. 1max corresponds to the maximum relative refractive index of the bounded core region, which is the refractive index of the inner core region at the outer radius r a The value Δ corresponds to the average relative refractive index of the trench cladding region. 3max corresponds to the relative refractive index of the trench cladding region at the inner radius r1 of the trench cladding region. The value Δ 3min corresponds to the relative refractive index of the trench cladding region at the outer radius r3 of the trench cladding region. V Trench refers to the trench volume. For modeling purposes, the optical fiber was assumed to include a primary coating with an outer diameter of 167 microns and a Young's modulus of approximately 0.21 MPa, and a secondary coating with an outer diameter of 200 microns and a Young's modulus of approximately 1700 MPa. [Table 1] [Table 2]

[0135] Table 3 summarizes selected optical and bending loss properties of modeled examples Ex1, Ex2, and Ex3. In Table 3, MFD refers to the mode field diameter at 1550 nm, and A eff refers to the effective area at 1550 nm, cable cutoff refers to the cable cutoff wavelength of 22 meters, dispersion refers to the dispersion at 1550 nm, 1 x 32 mm refers to the macrobend loss for one turn of fiber around a 32 mm diameter mandrel at 1550 nm, 1 x 40 mm refers to the macrobend loss for one turn of fiber around a 40 mm diameter mandrel at 1550 nm, 1 x 50 mm refers to the macrobend loss for one turn of fiber around a 50 mm diameter mandrel at 1550 nm, 1 x 60 mm refers to the macrobend loss for one turn of fiber around a 60 mm diameter mandrel at 1550 nm, and Attn refers to the attenuation at 1550 nm. Figures 7A-7C show the modeled microbending loss as a function of wavelength for 600 m to 700 m lengths of fiber wound around a drum with a radius of 153 mm covered with sandpaper (40 micron grade, Al2O3) at winding tensions of 30.0 g, 60.0 g, and 90.0 g. [Table 3]

[0136] The measured relative refractive index profiles of Experimental Examples Ex4 and Ex5 are shown in FIG. 8. The relative refractive index profiles of Experimental Examples Ex4 and Ex5 include a bounded core region having an outer core region surrounding and directly adjacent to the inner core region, a trench cladding region surrounding and directly adjacent to the outer core region, and an outer cladding region surrounding and directly adjacent to the trench cladding region. In the experimental examples, the transition region between the core region and the trench cladding region is sloped, and the transition region between the trench cladding region and the outer cladding region is sloped. The relative refractive index Δ3 within the trench cladding region in both experimental examples was sloped and had an approximately triangular shape.

[0137] The relative refractive index profile parameters of experimental examples Ex4 and Ex5 are given in Tables 4 and 5. The values ​​Δ 1max corresponds to the maximum relative refractive index of the bounded core region, which is the refractive index of the inner core region at the outer radius r a The value Δ 1min corresponds to the minimum relative refractive index of the bounded core region, which occurs at the outer radius r1 of the outer core region. The value Δ3 corresponds to the average relative refractive index of the trench cladding region. The value Δ 3max corresponds to the relative refractive index of the trench cladding region at the inner radius r1 of the trench cladding region. The value Δ 3min corresponds to the relative refractive index of the trench cladding region at the outer radius r3 of the trench cladding region. The value Δ corresponds to the average relative refractive index of the outer cladding region. The value Δ 4max corresponds to the maximum relative refractive index of the outer cladding region, which occurs at radial position r3. V Trench refers to trench volume. Experimental examples Ex4 and Ex5, and the comparative example (EX2000 available from Corning Incorporated), included a primary coating with an outer diameter of 167 microns and a Young's modulus of about 0.21 MPa, and a secondary coating with an outer diameter of 200 microns and a Young's modulus of about 1700 MPa. [Table 4] [Table 5]

[0138] Tables 6A and 6B summarize selected optical and bending loss properties of experimental examples Ex4 and Ex5 and a comparative example (EX2000, available from Corning Incorporated). In Table 6A, MFD refers to the mode field diameter at 1550 nm, and A eff refers to the effective area at 1550 nm, cable cutoff refers to the cable cutoff wavelength of 22 meters, dispersion refers to the dispersion at 1550 nm, 1 x 32 mm refers to the macrobend loss at 1550 nm for one turn of fiber around a 32 mm diameter mandrel, 1 x 50 mm refers to the macrobend loss at 1570 nm for one turn of fiber around a 50 mm diameter mandrel, 1 x 60 mm refers to the macrobend loss at 1625 nm for one turn of fiber around a 60 mm diameter mandrel, and Attn refers to the attenuation at 1550 nm. Table 6B reports the microbending losses at wavelengths of 1550 nm and 1625 nm determined at winding tensions of 30.0 g, 60.0 g, and 90.0 g by winding 600 m to 700 m of each fiber around a drum with a radius of 153 mm that is covered with sandpaper (40 micron grade, Al2O3). [Table 6] [Table 7]

[0139] FIG. 9 shows the measured microbending loss at 1550 nm as a function of winding force for Examples Ex4 and Ex5, and the Comparative Example. The winding force corresponds to the ratio of winding tension to drum diameter. Data from multiple measurement runs are shown. Square symbols represent data for Example Ex5. Diamond symbols represent data for Example Ex4. Circle symbols represent data for the comparative optical fiber. The Comparative Example has a much lower effective area (A eff ) in particular, the comparative example had a thickness of 115 μm 2 Less than the effective area (A eff ), whereas Experimental Examples Ex4 and Ex5 had a thickness of 115 μm 2 Ultra-effective area (A eff ) had a higher effective area (A eff ), Experimental Examples Ex4 and Ex5 nevertheless demonstrated microbending losses at 1550 nm that were comparable to those of the comparative example.

[0140] Eight additional experimental examples, Ex6 to Ex13, were prepared. Experimental examples Ex6 to Ex13 had the same relative refractive index profile and composition as those of Ex4 and Ex5. Specifically, each of experimental examples Ex6 to Ex13 had: (1) a radius r1 in the range of 5.5 μm to 9.0 μm, and a maximum relative refractive index Δ in the range of -0.05% to 0.05%. 1max (2) a core region having a relative refractive index profile Δ1 having a refractive index profile Δ1 of 20% μm 2 and (b) a cladding region surrounding and immediately adjacent to the core region, including a trench cladding region having a trench volume less than 115 μm at 1550 nm, and an outer cladding region surrounding the trench cladding region and immediately adjacent to the trench cladding region, the outer cladding region having a relative refractive index Δ4 in the range of −0.40% to 0.20%, and (3) a coating surrounding and immediately adjacent to the outer cladding region, the coating including an outer radius less than 110 μm. Each of Examples Ex6-Ex13 further exhibited the following attributes: (1) 115 μm at 1550 nm 2 ~135μm 2 Effective area Aeff (2) a macrobend loss of less than 0.200 dB / turn at 1550 nm as determined by mandrel wrap testing using a mandrel having a diameter of 32 mm, and (3) a macrobend loss of less than 0.030 dB / turn at 1550 nm as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm.

[0141] Examples Ex6-EX13 included a primary coating having an outer diameter of 167 microns and a Young's modulus of approximately 0.21 MPa, and a secondary coating having an outer diameter of 200 microns and a Young's modulus of approximately 1700 MPa.

[0142] Tables 7-10 summarize selected measured properties of Examples Ex6-Ex13. The relative refractive index profile parameters of Examples Ex6-EX13 are given in Tables 7 and 8. The values ​​Δ 1max corresponds to the maximum relative refractive index of the bounded core region, which is the refractive index of the inner core region at the outer radius r a The value Δ 1min corresponds to the minimum relative refractive index of the bounded core region, which occurs at the outer radius r1 of the outer core region. The value Δ3 corresponds to the average relative refractive index of the trench cladding region. The value Δ 3max corresponds to the relative refractive index of the trench cladding region at the inner radius r1 of the trench cladding region. The value Δ 3min corresponds to the relative refractive index of the trench cladding region at the outer radius r3 of the trench cladding region. The value Δ4 corresponds to the average relative refractive index of the outer cladding region. V Trench refers to the trench volume. In Tables 9 and 10, MFD refers to the mode field diameter at 1550 nm, and A effrefers to the effective area at 1550 nm, cable cutoff refers to the cable cutoff wavelength of 22 meters, dispersion refers to the dispersion at 1550 nm, 1 x 32 mm refers to the macrobend loss at 1550 nm for one turn of fiber around a 32 mm diameter mandrel, 1 x 50 mm refers to the macrobend loss at 1570 nm for one turn of fiber around a 50 mm diameter mandrel, 1 x 60 mm refers to the macrobend loss at 1625 nm for one turn of fiber around a 60 mm diameter mandrel, and Attn refers to the attenuation at 1550 nm. Table 9 reports the microbending losses at a wavelength of 1550 nm for Ex6–Ex11, determined at winding tensions of 30.0 g, 60.0 g, and 90.0 g by winding 600 m–700 m of each fiber around a drum with a radius of 153 mm covered with sandpaper (40 micron grade, Al2O3). [Table 8] [Table 9] [Table 10] [Table 11]

[0143] The macrobend loss at 1550 nm of the optical fiber disclosed herein, as determined by mandrel wrap testing using a mandrel having a diameter of 32 mm, is less than 0.300 dB / turn, or less than 0.250 dB / turn, or less than 0.200 dB / turn, or less than 0.150 dB / turn, or less than 0.100 dB / turn, or less than 0.050 dB / turn, in the range of 0.030 dB / turn to 0.300 dB / turn, or in the range of 0.050 dB / turn to 0.250 dB / turn, or in the range of 0.100 dB / turn to 0.200 dB / turn.

[0144] The macrobend loss at 1550 nm of the optical fiber disclosed herein, as determined by mandrel wrap testing using a mandrel having a diameter of 40 mm, is less than 0.200 dB / turn, or less than 0.150 dB / turn, or less than 0.100 dB / turn, or less than 0.050 dB / turn, or in the range of 0.030 dB / turn to 0.250 dB / turn, or in the range of 0.050 dB / turn to 0.200 dB / turn, or in the range of 0.100 dB / turn to 0.200 dB / turn.

[0145] The macrobend loss at 1550 nm of the optical fiber disclosed herein, as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm, is less than 0.035 dB / turn, or less than 0.030 dB / turn, or less than 0.025 dB / turn, or less than 0.020 dB / turn, or less than 0.015 dB / turn, or in the range of 0.005 dB / turn to 0.035 dB / turn, or in the range of 0.010 dB / turn to 0.030 dB / turn, or in the range of 0.015 dB / turn to 0.025 dB / turn.

[0146] The macrobend loss at 1625 nm of the optical fiber disclosed herein, as determined by mandrel wrap testing using a mandrel having a diameter of 60 mm, is less than 0.0030 dB / turn, or less than 0.0020 dB / turn, or less than 0.0010 dB / turn, or less than 0.00050 dB / turn, or less than 0.00010 dB / turn, or less than 0.00005 dB / turn, in the range of 0.00001 dB / turn to 0.0030 dB / turn, or in the range of 0.00005 dB / turn to 0.0020 dB / turn, or in the range of 0.00010 dB / turn to 0.0010 dB / turn.

[0147] The optical fiber disclosed herein, when wound with a tension of 30 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3), has a microbending loss at 1550 nm of less than 3.5 dB / km, or less than 3.0 dB / km, or less than 2.5 dB / km, or less than 2.0 dB / km, or less than 1.5 dB / km, or less than 1.0 dB / km, or less than 0.5 dB / km, or in the range of 0.2 dB / km to 3.5 dB / km, or in the range of 0.4 dB / km to 3.0 dB / km, or in the range of 0.6 dB / km to 2.5 dB / km, or in the range of 0.8 dB / km to 2.0 dB / km.

[0148] The optical fiber disclosed herein has a microbending loss at 1550 nm when wound with a tension of 60 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3) of less than 5.0 dB / km, or less than 4.0 dB / km, or less than 3.0 dB / km, or less than 2.5 dB / km, or less than 2.0 dB / km, or less than 1.5 dB / km, or in the range of 1.0 dB / km to 5.0 dB / km, or in the range of 1.5 dB / km to 4.5 dB / km, or in the range of 2.0 dB / km to 4.0 dB / km, or in the range of 2.2 dB / km to 3.5 dB / km.

[0149] The optical fiber disclosed herein, when wound with a tension of 90 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3), has a microbending loss at 1550 nm of less than 8.5 dB / km, or less than 8.0 dB / km, or less than 7.5 dB / km, or less than 7.0 dB / km, or less than 6.5 dB / km, or less than 6.0 dB / km, or less than 5.0 dB / km, or less than 4.0 dB / km, or less than 3.0 dB / km, or in the range of 1.5 dB / km to 8.5 dB / km, or in the range of 2.0 dB / km to 8.0 dB / km, or in the range of 2.5 dB / km to 7.5 dB / km, or in the range of 3.0 dB / km to 7.0 dB / km.

[0150] The optical fiber disclosed herein has a microbending loss at 1625 nm when wound with a tension of 30 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3), of less than 5.0 dB / km, or less than 4.0 dB / km, or less than 3.0 dB / km, or less than 2.0 dB / km, or less than 1.0 dB / km, or in the range of 0.3 dB / km to 5.0 dB / km, or in the range of 0.6 dB / km to 4.5 dB / km, or in the range of 0.8 dB / km to 4.0 dB / km, or in the range of 0.9 dB / km to 3.5 dB / km.

[0151] The optical fiber disclosed herein has a microbending loss at 1625 nm when wound with a tension of 60 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3) of less than 8.0 dB / km, or less than 7.0 dB / km, or less than 6.0 dB / km, or less than 5.0 dB / km, or less than 4.0 dB / km, or less than 3.0 dB / km, or less than 2.0 dB / km, or in the range of 1.0 dB / km to 8.0 dB / km, or in the range of 1.4 dB / km to 7.0 dB / km, or in the range of 1.8 dB / km to 6.0 dB / km, or in the range of 2.2 dB / km to 5.0 dB / km.

[0152] The optical fiber disclosed herein has a microbending loss at 1625 nm when wound with a tension of 90 g around a drum having a radius of 153 mm covered with sandpaper (40 micron, Al2O3) of less than 14.0 dB / km, or less than 12.0 dB / km, or less than 10.0 dB / km, or less than 8.0 dB / km, or less than 6.0 dB / km, or less than 4.0 dB / km, or in the range of 2.0 dB / km to 14.0 dB / km, or in the range of 3.0 dB / km to 12.0 dB / km, or in the range of 4.0 dB / km to 10.0 dB / km.

[0153] The optical fiber disclosed herein has an attenuation at 1550 nm of less than 0.175 dB / km, or less than 0.170 dB / km, or less than 0.165 dB / km, or less than 0.160 dB / km, or less than 0.155 dB / km, or less than 0.150 dB / km, or less than 0.145 dB / km, or in the range of 0.140 dB / km to 0.170 dB / km, or in the range of 0.145 dB / km to 0.165 dB / km.

[0154] The optical fiber disclosed herein has a mode field diameter at 1550 nm greater than 11.5 μm, or greater than 12.0 μm, or greater than 12.5 μm, or greater than 13.0 μm, or in the range of 11.5 μm to 13.5 μm, or in the range of 12.0 μm to 13.0 μm.

[0155] The optical fiber disclosed herein has an effective area of ​​110 μm at 1550 nm. 2 Over 115 μm 2 Over 120 μm 2 Over 125 μm 2 Over 130 μm 2 Over or 110 μm 2 ~140μm 2 Within the range of 115 μm 2 ~135μm 2 Within the range of 120 μm 2 ~130μm 2 is within the range.

[0156] The optical fiber disclosed herein has a dispersion at 1550 nm of less than 25.0 ps / ns-km, or less than 23.0 ps / ns-km, or less than 21.0 ps / ns-km, or in the range of less than 20.0 ps / ns-km to 25.0 ps / ns-km.

[0157] The cabled cutoff wavelength of the optical fiber disclosed herein is less than 1530 nm, or less than 1500 nm, or less than 1450 nm, or less than 1400 nm, or less than 1350 nm, or in the range of 1250 nm to 1500 nm, or in the range of 1300 nm to 1450 nm.

[0158] Embodiments of the optical fiber disclosed herein exhibit two or more of macrobend loss, mode field diameter at 1550 nm, effective area at 1550 nm, dispersion at 1550 nm, cable cutoff wavelength, attenuation at 1550 nm, microbend loss at 1550 nm, and microbend loss at 1625 nm within the ranges set forth above, as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm, as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm, as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm.

[0159] Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a particular order. Thus, unless a method claim actually recites the order in which its steps are to be followed, or the claim or specification specifically states that the steps are to be limited to a particular order, no particular order is intended to be inferred.

[0160] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the scope or spirit of the present invention. Since modifications, combinations, sub-combinations, and variations of the disclosed embodiments that incorporate the spirit and content of the present invention will occur to those skilled in the art, the present invention should be construed as including all that come within the scope of the appended claims and their equivalents.

Claims

1. An optical fiber, Radius r in the range of 5.5 μm to 9.0 μm １ , and a maximum relative refractive index Δ in the range of −0.05% to 0.05% １ｍａｘ a relative refractive index profile Δ １ a core region having a cladding region surrounding and immediately adjacent to said core region, said cladding region comprising: a trench cladding region surrounding the core region, the trench cladding region comprising silica glass and having a radius r ３ , relative refractive index Δ ３ , and 20% μm ２ a trench cladding region having a trench volume less than an outer cladding region surrounding and immediately adjacent to the trench cladding region, the outer cladding region having a radius r ４ , and a relative refractive index Δ in the range of −0.40% to −0.20% ４ an outer cladding region comprising silica glass having a coating surrounding and immediately adjacent the outer cladding region, the coating having an outer radius of 110 μm or less; The optical fiber has a 115 μm ２ ~135μm ２ and a macrobend loss of less than 0.300 dB / turn at 1550 nm as determined by mandrel wrap testing using a mandrel having a diameter of 32 mm and a macrobend loss of less than 0.030 dB / turn at 1550 nm as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm, and a macrobend loss of less than 0.030 dB / turn at 1550 nm as determined by mandrel wrap testing using a mandrel having a diameter of 50 mm. ２ O ３ and a microbending loss at 1550 nm of less than 3.0 dB / km as determined by wrapping with a tension of 30 g around a drum having a radius of 153 mm covered with a 1000 .mu.m (1000 .mu.m) fiber.

2. The core region is a delimited core region including an inner core region and an outer core region surrounding and immediately adjacent to the inner core region, the inner core region having a radius r in the range of 0.5 μm to 4.0 μm. ａ and the maximum relative refractive index Δ １ｍａｘ and the outer core region has the radius r １ and a minimum relative refractive index Δ in the range of −0.40% to −0.20%. １ｍｉｎ The optical fiber of claim 1 , having

3. 3. The optical fiber of claim 2, wherein the inner core region comprises a relative refractive index profile defined by an α profile having an α value less than 10, and the outer core region comprises a relative refractive index profile defined by an α profile having an α value greater than 10.

4. The optical fiber of claim 2 or 3, wherein the inner core region comprises silica glass doped with an alkali metal oxide.

5. The optical fiber according to any one of claims 2 to 4, wherein the outer core region comprises silica glass doped with fluorine.

6. The optical fiber according to any one of claims 1 to 5, wherein the core region comprises silica glass doped with an alkali metal oxide.

7. The trench cladding region surrounds and is immediately adjacent to the offset cladding region, the offset cladding region surrounds and is immediately adjacent to the core region, and the offset cladding region has a radius r ２ and the relative refractive index Δ ３ Relative refractive index Δ ２ The optical fiber according to any one of claims 1 to 6, having

8. The optical fiber according to any one of claims 1 to 7, wherein the trench cladding region is immediately adjacent to the core region.

9. The optical fiber according to any one of claims 1 to 8, wherein the trench cladding region has a thickness of less than 16.0 µm.

10. The radius r ３ The optical fiber according to any one of claims 1 to 9, wherein is in the range of 13.0 µm to 22.0 µm.

11. The relative refractive index Δ ３ The optical fiber according to any one of claims 1 to 10, wherein is in the range of -0.28% to -0.38%.

12. The relative refractive index Δ ４ and the relative refractive index Δ ３ The optical fiber according to any one of claims 1 to 11, wherein the difference between is in the range of 0.04 to 0.15%.

13. The optical fiber according to any one of claims 1 to 12, wherein the outer radius of the coating is less than or equal to 90 μm.

14. 14. The optical fiber of any one of claims 1 to 13, wherein the optical fiber has a macrobending loss at 1550 nm of less than 0.150 dB / turn, as determined by mandrel wrap testing using a mandrel having a diameter of 32 mm.

15. 15. The optical fiber of any one of claims 1 to 14, wherein the optical fiber has a macrobending loss at 1550 nm of less than 0.010 dB / turn, as determined by a mandrel wrap test using a mandrel having a diameter of 50 mm.

16. 16. The optical fiber of any one of claims 1 to 15, wherein the optical fiber has a macrobending loss at 1550 nm of less than 0.0030 dB / turn, as determined by mandrel wrap testing using a mandrel having a diameter of 60 mm.

17. The optical fiber according to any one of the preceding claims, wherein the microbending losses at 1550 nm are less than 1.5 dB / km.

18. The optical fiber according to any one of the preceding claims, wherein the optical fiber has an attenuation at 1550 nm of less than 0.155 dB / km.

19. The optical fiber according to any one of the preceding claims, wherein the optical fiber has a mode field diameter at 1550 nm in the range of 11.5 μm to 13.5 μm.

20. The optical fiber has a 120 μm ２ The optical fiber of any one of claims 1 to 19, having an effective area of ​​greater than

21. The optical fiber has a 125 μm ２ The optical fiber of any one of claims 1 to 20, having an effective area of ​​greater than

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