Compliant optical fiber with upper doped outer cladding

Abstract

An optical fiber includes a core region having a relative refractive index profile [Delta] 1 with a maximum relative refractive index [Delta] 1 max in a range of from 0.20% to 0.50%; and a surrounding cladding region comprising a triangular trench cladding region and an outer cladding region, having a relative refractive index [Delta] 3 of greater than-0.60% and less than 0.00% of a minimum relative refractive index [Delta] 3 min, and a trench volume of greater than 30% [mu] m2. The relative refractive index [Delta] 4 of the outer cladding region is in the range of 0.01% to 0.06%, and the chlorine concentration is greater than 1500 ppm. The optical fiber has a mode field diameter of greater than 9.0 microns at 1310 nm, a cable cutoff wavelength of less than 1260 nm, a zero dispersion wavelength between 1300 nm and 1324 nm, and low macrobend loss.

Description

[0001] This application claims the benefit of priority under 35 U.S.C. §120 to U.S. Provisional Application Serial No. 63 / 356,193, filed on June 28, 2022, the contents of which are based and are incorporated herein by reference in their entirety. Technical Field

[0002] The present disclosure relates generally to optical fibers and, more particularly, to compliant diameter optical fibers having large MDF, good bending performance at small and large bend radii, and manufacturing cost-effectiveness. Background Art

[0003] Optical fiber is widely used in telecommunication applications. Optical fiber with a small cladding and / or coating diameter is attractive for reducing cable size, reducing cable cost, and increasing bandwidth density of optical interconnects. Optical fiber with an MFD greater than 9.0 microns at 1310 nm and optically compliant with the ITU-G.657.A2 specification is becoming increasingly important for high fiber density cables used in data center interconnects and smaller diameter cables in high density duct applications. It would be desirable to provide an optical fiber that has good bending performance at small and large bend radii with an improved profile that provides a high mode field diameter. Summary of the invention

[0004] According to one embodiment of the present disclosure, an optical fiber is provided. The optical fiber comprises: a core region, the core region having an outer radius r1 in the range of 4.0 μm to 8.0 μm, a maximum relative refractive index Δ 1max A relative refractive index distribution Δ1 in the range of 0.20% to 0.50%; a cladding region, the cladding region surrounding the core region and directly adjacent to the core region, the cladding region including a trench cladding region surrounding the core region, the trench cladding region having a triangular shape, an inner radius r2, an outer radius r3, a minimum relative refractive index Δ 3min Relative refractive index Δ3 greater than -0.60% and less than 0.00%, and greater than 30% μm 2 and an outer cladding region surrounding and directly adjacent to the trench cladding region, the outer cladding region having an outer radius r4 and a relative refractive index Δ4 in the range of 0.01% to 0.06% and a chlorine concentration greater than 1000 ppm. The optical fiber also includes a mode field diameter greater than 9.0 microns at 1310 nm, a cable cutoff wavelength less than 1260 nm, and a zero dispersion wavelength between 1300 nm and 1324 nm, wherein the optical fiber has a macrobending loss of less than 0.5 dB / turn at 1550 nm according to a mandrel winding test using a mandrel having a diameter of 15 mm, and wherein the optical fiber has a macrobending loss of less than 0.003 dB / turn at 1550 nm according to a mandrel winding test using a mandrel having a diameter of 30 mm.

[0005] It should be understood that both the above 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. The accompanying drawings are included to provide a further understanding and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate one or more embodiments and together with the description serve to explain the principles and operation of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an end view of an optical fiber having a core region surrounded by an inner cladding, a trench cladding, and a cladding region according to one example;

[0007] Figure 2 is a graph showing a refractive index profile of an optical fiber having an offset triangular trench according to an example;

[0008] Figure 3 is a graph showing a refractive index profile of an optical fiber having an offset triangular trench according to another example;

[0009] Figure 4 is a graph illustrating a refractive index profile of an optical fiber having an offset triangular trench according to a further example. DETAILED DESCRIPTION

[0010] The present disclosure is provided as feasible teaching and can be more easily understood by reference to the following description, drawings, examples and claims. To this end, those skilled in the relevant art will recognize and understand that many changes can be made to the various aspects of the embodiments described herein while still obtaining beneficial results. It is also obvious that some of the expected benefits of the present embodiment can be obtained by selecting some of the features without utilizing other features. Therefore, those skilled in the art will recognize that many modifications and adaptations are possible, and may even be desirable in some cases, and are part of the present disclosure. Therefore, it should be understood that unless otherwise stated, the present disclosure is not limited to the specific compositions, products, devices and methods disclosed. It should also be understood that the terms used herein are only for the purpose of describing specific aspects and are not intended to be restrictive.

[0011] Throughout this specification and the claims that follow, reference will be made to a number of terms which shall be defined to have the following meanings:

[0012] The terms "include", "including" or similar terms mean including but not limited to, ie, being inclusive rather than exclusive.

[0013] As used herein, the term "about" means that the amount, size, formula, parameter, and other quantities and properties are not and do not need to be exact, but can be approximate and / or larger or smaller as desired, thereby reflecting tolerances, conversion factors, rounding, measurement errors, etc. and other factors known to those skilled in the art. When a value is referred to as being approximately or approximately equal to a number, the value is within ±10% of the number. For example, a value of about 10 refers to a value between 9 and 11 (including 9 and 11). When the term "about" is used in describing the endpoints of a value or range, the disclosure should be understood to include the specific value or endpoint referred to. Whether or not the endpoint of a numerical value or range in the specification is recorded as "about", the endpoint of the numerical value or range is intended to include two embodiments: one modified by "about" and one not modified by "about". It will also be understood that the endpoint of each range is important relative to the other endpoint and is independent of the other endpoint.

[0014] Unless otherwise indicated, the term "about" further refers to all items within the range. For example, about 1, 2 or 3 is equivalent to about 1, about 2 or about 3, and further includes from about 1 to 3, from about 1 to 2 and from about 2 to 3. The specific and preferred numerical values ​​and ranges disclosed in compositions, ingredients, ingredients, additives and the like are only for illustration, and they do not exclude other limited numerical values ​​or other numerical values ​​within the limited range. 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.

[0015] As used herein, the indefinite article "a" or "an" and the corresponding definite article "the" mean at least one, or one or more, unless stated otherwise.

[0016] In the case of recording a numerical range including an upper limit and a lower limit in this article, unless otherwise specified in a particular case, the range is intended to include its endpoints and all integers and fractions within the range. The scope of the claim is not intended to be limited to the specific values ​​cited when defining the range. In addition, when an amount, distance, concentration or other value or parameter is given as a list of a range, one or more preferred ranges, or an upper preferred value and a lower preferred value, this should be understood as specifically disclosing all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether these pairs are disclosed separately. Finally, when the term "about" is used in describing the endpoints of a value or range, the disclosure should be understood to include the specific value or endpoint referred to. When the endpoint of a numerical value or range is not recorded as "about", the endpoint of the numerical value or range is intended to include two embodiments: one is modified by "about", and one is not modified by "about".

[0017] 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 may be present other than those specifically recited in the list.

[0018] The term "wherein" is used as an open transition phrase to introduce a statement of a series of properties of the structure.

[0019] The terms "comprising" and "comprises", for example "A comprises B", are intended to include special cases of the concept of "consisting of", as in "A consists of B".

[0020] As used herein, the term "or" is inclusive; more specifically, the phrase "A or B" means "A, B, or both A and B." An exclusive "or" is specified herein, for example, by terms such as "either A or B" and "one of A or B."

[0021] As used herein, contact refers to direct contact or indirect contact. Direct contact refers to contact in the absence of an intermediate material, and indirect contact refers to contact through one or more intermediate materials. Directly contacted elements touch each other. Indirectly contacted elements do not touch each other, but are rigidly or flexibly connected through one or more intermediate materials. Contact refers to making two elements contact directly or indirectly. Direct (indirect) contacted elements can be said to be directly (indirectly) in contact with each other.

[0022] As used herein, "directly adjacent" means directly in contact, and "indirectly adjacent" means indirect contact. The term "adjacent" encompasses elements that are directly or indirectly adjacent to each other. The term "directly surrounding" means "surrounding and directly adjacent to"

[0023] "Optical fiber" refers to a waveguide having a glass portion surrounded by a coating. The glass portion includes a core and a cladding, and is referred to herein as a "glass fiber."

[0024] "Radial position," "radius," or radial coordinate "r" refers to the radial position relative to the centerline of the glass fiber (r=0).

[0025] The terms "inner" and "outer" are used to refer to relative values ​​of radial coordinates or relative positions of regions of an optical fiber, where "inner" means closer to the centerline of the glass fiber than "outer". The inner radial coordinate is closer to the centerline of the glass fiber than the outer radial coordinate. The inner radial coordinate is between the centerline of the glass fiber and the outer radial coordinate. The inner region of the optical fiber is closer to the centerline of the glass fiber than the outer region. The inner region of the optical fiber is between the centerline of the glass fiber and the outer region of the glass fiber.

[0026] The term "mode" refers to the guided mode. Single-mode optical fiber is designed to support only the primary LP mode over a considerable length of the fiber (e.g., at least several meters). 01 mode, but in some cases can support multiple modes over short distances (e.g., tens of centimeters). The optical fiber disclosed herein is a single-mode optical fiber at a wavelength of 1550 nm.

[0027] The term "μm" or "micron" means micrometers; i.e. 10 -6 m.

[0028] The term "ppm" means parts per million by weight. Weight percent (wt %) measurements can be converted to ppm by multiplying by a factor of 10,000.

[0029] The “refractive index” refers to the refractive index at a wavelength of 1550 nm.

[0030] "Refractive index profile" is the relationship between the refractive index or relative refractive index and the radius. For the relative refractive index profile described herein as having a step boundary between adjacent core and / or cladding regions, normal changes in processing conditions can hinder the acquisition of sharp step boundaries at the interface of adjacent regions. It should be understood that although the boundary of the refractive index profile can be described herein as a step change in the refractive index, in practice the boundary can be circular or otherwise deviate from the perfect step function property. It is further understood that the value of the relative refractive index can change with the radial position in any cladding region in the core region and / or cladding region. When the relative refractive index changes with radial position in a specific region of the optical fiber (e.g., any cladding region in the core region and / or cladding region), it is represented according to its actual or approximate functional dependence, or its value at a specific position in the region, or according to the average value applicable to the entire region. Unless otherwise specified, if the relative refractive index of a region (e.g., a core region and / or any of the cladding regions) is expressed as a single value or parameter applicable to the entire region (e.g., Δ or Δ % or %), it is understood that the relative refractive index in the region is constant or approximately constant and corresponds to a single value, or that the single value or parameter represents an average value of a non-constant relative refractive index that is related to radial position within the region. For example, if "i" is a region of glass fiber, the parameter Δ i is given by the following equation (2): ave The average value of the relative refractive index in a defined area, unless otherwise stated. Whether by design or due to normal manufacturing variability, the dependence of the relative refractive index on radial position may be tilted, curved, or otherwise non-constant.

[0031] As used herein, in equation (1), for any radial position r, the "relative refractive index" is defined as: where n(r) is the refractive index at radial position r in the glass fiber, unless otherwise stated, and n ref is the refractive index of pure silica glass. For the purposes of this disclosure, n ref =1.444, which is the refractive index of pure silica at 1550 nm. Therefore, as used herein, the relative refractive index percentage is relative to pure silica glass. As used herein, unless otherwise specified, the relative refractive index is represented by Δ (or "delta") or Δ% (or "delta %"), and its value is in "%". The relative refractive index may also be expressed as Δ(r) or Δ(r)%. When referring to a specific region i of the optical fiber, the relative refractive index may also be expressed as Δ i ,Δ i %,Δ i (r) or Δ i (r)%.

[0032] The average relative refractive index of the fiber region (Δ ave ) is determined by equation (2): where r inner is the inner radius of the region, r outer is the outer radius of the region and Δ(r) is the relative refractive index of the region specified in equation (1).

[0033] The term "α-profile" refers to a relative refractive index profile Δ(r) having the functional form defined in equation (3): where r o is the radial position where Δ(r) reaches its maximum value, r z (r z >r0) is the radial position where Δ(r) decreases to its minimum value, and r is at r i ≤r≤r f In the range of i is the initial radial position of the α-distribution, r f is the final radial position of the α-distribution, and α is a real number. For the α-distribution, Δ(r0) may be referred to herein as Δ max , or when referring to a specific region i of the optical fiber, it is called Δ i,max When r0 occurs at the center line (r = 0) and r z When the α-profile corresponding to the outer radius r1 of the core region and Δ1(r1)=0 describes the relative refractive index distribution of the optical fiber core region, equation (3) can be simplified to equation (4):

[0034] The "effective area" of a fiber is defined as: where f(r) is the transverse component of the electric field of the guided optical signal and r is the radial position in the fiber. Unless otherwise specified, the “effective area” or “A eff ” depends on the wavelength of the optical signal and is understood herein to refer to a wavelength of 1550 nm.

[0035] The "mode field diameter" or "MFD" of an optical fiber is defined in equation (5) as: Where f(r) is the transverse component of the electric field distribution of the guided optical signal, and r is the radial position in the fiber. The "mode field diameter" or "MFD" depends on the wavelength of the optical signal in the fiber. When referring to the mode field diameter in this article, the wavelength will be specifically indicated. Unless otherwise stated, the mode field diameter refers to the LP at the specified wavelength. 01 model.

[0036] "Trench" or "trench region" or "trench cladding region" refers to the portion of the cladding surrounded by and directly 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 a preferred embodiment, the inner cladding region surrounds and is directly adjacent to the core, and the trench cladding region surrounds and is directly adjacent to the inner cladding region, wherein the inner cladding region has a relative refractive index Δ2 that is less than the relative refractive index Δ1 of the core and greater than the relative refractive index Δ3 of the trench cladding region.

[0037] “Groove Volume” is defined as: where r Trench,inner is the inner radius r2 of the trench cladding region, r Trench,outer is the outer radius r3 of the trench cladding region, Δ Trench (r) = Δ3(r) is the relative refractive index of the trench cladding region, and Δ4 is ​​the average relative refractive index of the outer cladding region of the glass fiber. In embodiments where the trench cladding region is directly adjacent to the core region, r2 = r1. In embodiments where the trench cladding region is directly adjacent to the inner cladding region, r Trench,inner is r2(r2>r1), r Trench,outer is r3, and Δ Trench is Δ3(r). The groove volume is defined as an absolute value and has a positive value. The groove volume is expressed in this article as %Δ-micron2 ,%Δ-μm 2 ,or%-micron 2 ,%-μm 2 These units are used interchangeably herein.

[0038] Unless otherwise stated, the "chromatic dispersion" of an optical fiber (referred to herein as dispersion) is the sum of the material dispersion, waveguide dispersion, and intermodal dispersion. In the case of a single-mode waveguide fiber, the intermodal dispersion is zero. Dispersion values ​​in dual-mode mode assume zero intermodal dispersion. This paper reports the dispersion at wavelengths of 1310 nm and 1550 nm and is expressed in units of ps / nm-km.

[0039] The cutoff wavelength of an optical fiber is the minimum wavelength at which the fiber supports only one propagation mode. The cutoff wavelength will be reported in this article as the cable cutoff wavelength. The cable cut-off wavelength is based on the 22-meter cable fiber length specified by the Telecommunications Industry Association (TIA) in TIA-455-80:FOTP-80IEC-60793-1-44 "Optical Fiber - Part 1-44: Measurement Methods and Test Procedures - Cut-off Wavelength" (May 21, 2003).

[0040] The term "bend diameter" refers to the mandrel diameter used to determine macrobending losses using the mandrel wrap test specified by the Telecommunications Industry Association (TIA) in standard TIA-455-62: FOTP-62IEC-60793-1-47 "Optical Fiber - Part 1-47: Measurement Methods and Test Procedures - Macrobending Losses".

[0041] The optical fiber disclosed herein comprises 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 comprises a plurality of regions whose relative refractive index may be different. The plurality of cladding regions are preferably concentric regions. In a preferred embodiment, the cladding region comprises 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 a preferred embodiment, the trench cladding region is directly adjacent to the inner cladding region, and the inner cladding region is directly adjacent to the core region. The core region, the cladding region, the inner cladding region, the trench cladding region and the outer cladding region are also referred to as the core, the cladding, the inner cladding, the trench and the outer cladding, respectively.

[0042] Whenever used in this document, 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 inner cladding region, radial position r3 and relative refractive index Δ3 or Δ3(r) refer to the trench cladding region, and radial position r4 and relative refractive index Δ4 or Δ4(r) refer to the outer cladding region.

[0043] The relative refractive index Δ1(r) has a 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 4min In embodiments where the relative refractive index is constant or approximately constant over a region, the maximum and minimum values ​​of the relative refractive index are equal or approximately equal.

[0044] It should be understood that the core region is the central region of the glass fiber and is substantially cylindrical, and the surrounding inner cladding region, the surrounding groove cladding region and the surrounding outer cladding region are substantially annular. The annular region can be characterized according to the inner radius and the outer radius. The radial positions r1, r2, r3 and r4 refer to the outermost radius of the core region, the inner cladding region, the groove cladding region and the outer cladding region respectively in this article. The radius r4 corresponds to the outer radius of the glass fiber.

[0045] When two regions are directly adjacent to each other, the outer radius of the inner region of the two regions is consistent with the inner radius of the outer region of the two regions. In one embodiment, for example, the glass fiber includes a groove cladding region surrounded by an outer cladding region and directly adjacent to the outer cladding region. In such embodiments, the radius r3 corresponds to the outer radius of the groove cladding region and the inner radius of the outer cladding region. In a preferred embodiment herein, the groove cladding region has an inner radius r2 and an outer radius r3, the radius r2>r1 and the radius r2 corresponds to the outer radius of the inner cladding region and the inner radius of the groove cladding region.

[0046] The following terms apply to the disclosed embodiments, wherein the relative refractive index profile includes an inner cladding region surrounding and directly adjacent to the core region, a trench cladding region surrounding and directly adjacent to the inner cladding region, and an outer cladding region surrounding and directly adjacent to the trench cladding region. The difference between radial position r2 and radial position r1 is referred to herein as the thickness or width of the inner cladding region. In all embodiments, the difference between radial position r3 and radial position r2 is referred to herein as the thickness or width of the trench cladding region. The difference between radial position r4 and radial position r3 is referred to herein as the thickness or width of the outer cladding region.

[0047] As will be further described below, the relative refractive index of the core region, the inner cladding region, the trench cladding region, and the outer cladding region is different. Each region is formed by doped or undoped silica glass. The change in the refractive index relative to the undoped silica glass is achieved by doping an up dopant or a down dopant at a specific level to provide a target refractive index or refractive index profile using techniques known to those skilled in the art. The down dopant is a dopant that reduces the refractive index of the glass relative to the undoped glass composition. In one embodiment, the undoped glass is pure silica glass. When the undoped glass is pure silica glass, the up dopant includes Cl, Br, Ge, Al, P, Ti, Zr, Nb and Ta, and the down dopant includes F and B. A constant refractive index region can be formed by not doping (e.g., pure silica) or doping with a uniform concentration. A variable refractive index region is formed by a non-uniform spatial distribution of dopants and / or by doping different dopants in different regions. The refractive index varies approximately linearly with the concentration of the up dopant or the down dopant. For example, in silica glass, for every 1 wt % Cl doped as a dopant, the relative refractive index increases by about 0.063% Δ, and in silica glass, for every 1 wt % F doped as a dopant, the relative refractive index decreases by about 0.32%.

[0048] The coating formed on the glass fiber is formed by a curable coating composition. The curable coating composition includes one or more curable components. As used herein, the term "curable" means that when exposed to a suitable curing energy source, the component includes one or more curable functional groups capable of forming a covalent bond, which participates in connecting the component to itself or to other components of the coating composition. The product obtained by curing the curable coating composition is referred to as the cured product of the composition in this article. The cured product is preferably a polymer. The curing process is induced by energy. The energy form includes radiation or thermal energy. In a preferred embodiment, curing occurs with radiation, wherein radiation refers to electromagnetic radiation. The curing induced by radiation is referred to as radiation curing or photocuring in this article. The radiation-curable component is a component that can be induced to undergo a curing reaction when exposed to radiation for a sufficiently long period of time at a suitable wavelength and a suitable intensity. Suitable wavelengths include wavelengths of infrared, visible light or ultraviolet parts of the electromagnetic spectrum. The radiation curing reaction occurs in the presence of a photoinitiator. The radiation-curable component can also be heat-curable. Similarly, a heat-curable component is a component that can induce a curing reaction after being exposed to heat energy of sufficient intensity for a sufficiently long time. The heat curable component may also be radiation curable.

[0049] Curable components include one or more curable functional groups. Curable components with only one curable functional group are referred to as monofunctional curable components in this article. Curable components with two or more curable functional groups are referred to as multifunctional curable components in this article. Multifunctional curable components include two or more functional groups that can form covalent bonds during the curing process, and crosslinking can be introduced into the polymer network formed in the curing process. Multifunctional curable components may also be referred to as "crosslinking agents" or "curable crosslinking agents" in this article. Curable components include curable monomers and curable oligomers. Examples of functional groups that participate in the formation of covalent bonds in the curing process are determined below.

[0050] The term "(meth)acrylate" means methacrylate, acrylate, or a combination of methacrylate and acrylate.

[0051] Reference will now be made in detail to illustrative embodiments of the present specification.

[0052] refer to Figure 1 According to one example, the termination of the optical fiber 10 is shown with a glass fiber 12 including a core region 30 surrounded by a cladding region, the cladding region including an inner cladding region 32, a trench cladding region 34, and an outer cladding region 16. The core region 30 defines the core of the glass fiber 12 and may be a glass core region that is circular in cross-section. The glass fiber 12 is surrounded by an outer coating 20, which may include a primary coating 22 surrounded by a secondary coating 24. Additionally, a tertiary layer (e.g., an ink layer, not shown) may surround the secondary coating 24.

[0053] Optical fiber 10 advantageously has a 1310 nm mode field diameter (MFD) greater than 9.0 microns and exhibits low macrobending losses at both small and large bend diameters.

[0054] The present disclosure relates to glass fibers and optical fibers having low macrobending losses at bend diameters between 10 mm and 40 mm. Bend diameters greater than 25 mm are typically encountered when attaching connectors to optical fibers, and bend diameters less than 25 mm are typically encountered when placing or configuring optical fibers in narrow or compact installation spaces. As described herein, macrobending losses at bend diameters in the range of 10 mm to 40 mm can be mitigated by appropriately designing the refractive index profile of the optical fiber. In particular, the inclusion of a trench cladding region between the core region and the cladding region reduces macrobending losses over a wide range of bend diameters.

[0055] Glass fiber. The optical fiber disclosed herein includes a glass fiber 12 having a core region 30 and a cladding region surrounding the core region 30 and a coating surrounding the cladding region. The glass fiber 12 including the core region 30 and the cladding region is glass. The glass fiber 12 includes the core region 30, the inner cladding region 32, the trench cladding region 34, and the outer cladding region 16. The core region 30 has a higher refractive index than the cladding region, and the glass fiber 12 functions as a waveguide.

[0056] The cross section of the core region 30 is circular, and the outer radius r1 ranges from 4.0 μm to 8.0 μm, and the relative refractive index distribution Δ1 has a maximum relative refractive index Δ 1max The cladding region surrounds the core region 30 and is directly adjacent to the core region 30 . Figure 1 The cladding region in the embodiment of the present invention includes an inner cladding region 32 directly surrounding the core region 30 and having an outer radius r2. The cladding region also includes a trench cladding region 34, which directly surrounds the inner cladding region 32 and has an inner radius r2 and an outer radius r3. The trench cladding region 34 has a relative refractive index Δ3, wherein the minimum relative refractive index Δ 3min Greater than -0.60% and less than 0.00%. The trench cladding region 34 has a greater than 30% μm 2 The outer cladding region 16 directly surrounds the trench cladding region 34. According to one embodiment, the outer cladding region 16 has an outer radius r4 and a relative refractive index Δ4 in the range of 0.00% to 0.10%.

[0057] The optical fiber 10 includes a primary coating 22 surrounding and directly adjacent to a cladding region. The primary coating 22 has a radius r5, an in-situ modulus in the range of 0.05 MPa to 0.30 MPa, and a thickness r5-r4 in the range of 10.0 μm to 25.0 μm. In addition, the optical fiber has a secondary coating 24 surrounding and directly adjacent to the primary coating 22. According to one embodiment, the secondary coating 24 has a radius r6 less than or equal to 100.0 μm, a Young's modulus greater than 1600 MPa, and a thickness r6-r5 in the range of 8.0 μm to 20.0 μm. According to another embodiment, the thickness r6-r5 of the secondary coating 24 is in the range of 8.0 μm to 17.0 μm.

[0058] In one embodiment, the optical fiber 10 has a mode field diameter greater than 9.0 μm at 1310 nm, a cable cutoff wavelength less than 1260 nm and a zero dispersion wavelength between 1300 nm and 1324 nm. In this embodiment, the optical fiber has a macrobending loss of less than 0.5 dB / turn at 1550 nm according to a mandrel winding test using a mandrel with a diameter of 15 mm. In addition, the optical fiber has a macrobending loss of less than 0.003 dB / turn at 1550 nm according to a mandrel winding test using a mandrel with a diameter of 30 mm.

[0059] The core region includes silica glass. The silica glass of the core region 30 can be undoped silica glass, top-doped silica glass and / or bottom-doped silica glass. In one embodiment, the silica glass of the core region is germanium (Ge)-free; that is, the core region 30 includes silica glass lacking germanium (Ge). In another embodiment, the core region 30 includes silica glass doped with germanium dioxide (GeO2). Embodiments of top-doped silica glass include silica glass doped with alkali metal oxides (e.g., Na2O, K2O, Li2O, Cs2O, or Rb2O) and / or halogens (Cl or Br). The bottom-doped silica glass includes silica glass doped with F.

[0060] In some embodiments, the core region includes an up-dopant and a down-dopant, wherein the concentration of the up-dopant is highest at the centerline (r=0) (in embodiments without a centerline tilt) or near the centerline (r=0) (in embodiments with a centerline tilt) and lowest at radius r1, and the concentration of the down-dopant is lowest at the centerline (r=0) and highest at radius r1. In such embodiments, the relative refractive index Δ1 may have a positive value near the centerline (r=0) and decrease to a negative value at radius r1.

[0061] In some embodiments, the relative refractive index of the core region 30 of the glass fiber is described by an α-profile, wherein the α value is in the range of 1.5 to 10, or in the range of 1.7 to 8.0, or in the range of 1.8 to 6.0, or in the range of 1.9 to 5.0, or in the range of 1.95 to 4.5, or in the range of 2.0 to 4.0, or in the range of 2.0 to 20, or in the range of 4.0 to 15, or in the range of 10 to 100, or in the range of 11 to 40, or in the range of 12 to 30. As the α value increases, the relative refractive index profile more closely resembles a step index profile. For purposes of this disclosure, an α profile having an α value greater than or equal to 10 is considered a step index curve.

[0062] The outer radius r1 of the core region 30 is in the range of 4.0 μm to 8.0 μm, or in the range of 4.5 μm to 7.5 μm, or in the range of 5.0 μm to 7.0 μm.

[0063] The relative refractive index Δ of the core region 30 1max In the range of 0.20% to 0.50%, or in the range of 0.25% to 0.45%, or in the range of 0.30% to 0.40. The relative refractive index Δ of the core region 30 1max In the range of -0.10% to 0.10%, or in the range of -0.05% to 0.05%, or in the range of -0.02% to 0.40.

[0064] In some embodiments, the relative refractive index of core region 30 is described by a step-index profile having a refractive index corresponding to Δ 1max A constant or approximately constant value, Δ 1max Extends over at least 70%, or at least 80%, or at least 90% of the distance between the optical fiber centerline (r=0) and the outer radius r1.

[0065] Figure 1 The cladding region of the illustrated embodiment includes an inner cladding region 32 directly adjacent to the core region 30 and a trench cladding region 34 directly adjacent to the inner cladding region 32. The inner cladding region 32 has an inner radius r1 and an outer radius r2 as defined above, r2>r1. The outer radius r2 of the inner cladding region 32 is in the range of 6.0 μm to 15.0 μm, or in the range of 6.5 μm to 12.5 μm, or in the range of 7.0 μm to 11.0 μm. The thickness r2-r1 of the inner cladding region 32 is in the range of 1.0 μm to 10.0 μm, or in the range of 2.0 μm to 9.0 μm, or in the range of 3.0 μm to 8.0 μm, or in the range of 3.5 μm to 7.0 μm. The relative refractive index Δ2 of the inner cladding region 32 is in the range of -0.10% to 0.10%, or in the range of -0.05% to 0.05%, or in the range of -0.02% to 0.02%.

[0066] The trench cladding region 34 may include down-doped silica glass. According to one example, the down-dopant is F (fluorine). The relative refractive index Δ3 or Δ 3minGreater than -0.60% and / or less than 0.00%, or greater than -0.55% and / or less than -0.10%, or greater than -0.50% and / or less than -0.20%, or greater than -0.45% and / or less than -0.25%, or in the range of -0.05% to -0.60%, or in the range of -0.10% to -0.55%, or in the range of -0.15% to -0.50%, or in the range of -0.20% to -0.55%, or in the range of -0.25% to -0.50%, or in the range of -0.25% to -0.50%. In some embodiments, the relative refractive index Δ3 decreases monotonically from the inner radius r2 to the outer radius r3. In one embodiment, the monotonic decrease in Δ3 exhibits a constant or approximately constant slope. In such embodiments, the trench cladding region 34 is referred to herein as a triangular trench. The monotonic decrease in Δ3 decreases from a maximum value Δ at or near the inner radius r2 to a value greater than -0.60% and / or less than 0.00%, or greater than -0.55% and / or less than -0.10%, or greater than -0.50% and / or less than -0.20%, or greater than -0.45% and / or less than -0.25%, or in the range of -0.05% to -0.60%, or in the range of -0.10% to -0.55%, or in the range of -0.15% to -0.50%, or in the range of -0.20% to -0.55%, or in the range of -0.25% to -0.50%. In some embodiments, the relative refractive index Δ3 decreases monotonically from the inner radius r2 to the outer radius r3. In one embodiment, the monotonic decrease in Δ3 exhibits a constant or approximately constant 3max The minimum value Δ extending to or near the outer radius r3 3min . Relative refractive index Δ 3max In the range of -0.10% to 0.10%, or in the range of -0.05% to 0.05%, or in the range of -0.02% to 0.02%. In one embodiment, the relative refractive index Δ 3max and relative refractive index Δ 1min In another embodiment, the relative refractive index Δ 3max Equal or approximately equal to the relative refractive index Δ2.

[0067] The inner radius r2 of the trench cladding region 34 is preferably r2>r1 and has the above-specified values. The outer radius r3 of the trench cladding region 34 is in the range of 12.0 μm to 25.0 μm, or in the range of 13.0 μm to 23.0 μm, or in the range of 14.0 μm to 21.0 μm, or in the range of 15.0 μm to 20.0 μm. The thickness r3-r2 of the trench cladding region 34 is in the range of 4.0 μm to 14.0 μm, or in the range of 5.0 μm to 13.0 μm, or in the range of 6.0 μm to 12.0 μm.

[0068] The trench volume of the trench cladding region 34 is greater than 30% μm 2 , or greater than 35% μm 2 , or greater than 40% μm 2 , or greater than 45% μm 2 , or greater than 50% μm 2 , or greater than 55% μm 2 , or at 30% μm 2 Up to 65% μm 2 within the range of 35% μm 2 Up to 60% μm2 within the range of 40% μm 2 Up to 55% μm 2 The thickness r3-r2 of the trench cladding region 34, the relative refractive index (Δ3, Δ 3min and / or Δ 3max ) and / or the relative refractive index of the outer cladding region (Δ4) and the relative refractive index of the trench cladding region (Δ3, Δ 3min and / or Δ 3max ) to control the groove volume.

[0069] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.60% to 0.00%, and the thickness r3 - r2 of the trench cladding region 34 is in the range of 4.0 μm to 15.0 μm, or in the range of 5.5 μm to 13.0 μm, or in the range of 6.0 μm to 12.0 μm, or in the range of 7.0 μm to 10.0 μm.

[0070] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.55% to -0.10%, and the thickness r3 - r2 of the trench cladding region 34 is in the range of 4.0 μm to 15.0 μm, or in the range of 5.5 μm to 13.0 μm, or in the range of 6.0 μm to 12.0 μm, or in the range of 7.0 μm to 10.0 μm.

[0071] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.50% to -0.20%, and the thickness r3 - r2 of the trench cladding region 34 is in the range of 4.0 μm to 15.0 μm, or in the range of 5.5 μm to 13.0 μm, or in the range of 6.0 μm to 12.0 μm, or in the range of 7.0 μm to 10.0 μm.

[0072] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.45% to -0.25%, and the thickness r3 - r2 of the trench cladding region 34 is in the range of 4.0 μm to 15.0 μm, or in the range of 5.5 μm to 13.0 μm, or in the range of 6.0 μm to 12.0 μm, or in the range of 7.0 μm to 10.0 μm.

[0073] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3minIn the range of -0.60% to 0.00%, and the trench volume is greater than 30% μm 2 , or greater than 35% μm 2 , or greater than 40% μm 2 , or greater than 45% μm 2 , or greater than 50% μm 2 , or greater than 55% μm 2 , or at 30% μm 2 Up to 65% μm 2 within the range of 35% μm 2 Up to 60% μm 2 within the range of 40% μm 2 Up to 55% μm 2 within the range.

[0074] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.55% to -0.10%, and the trench volume is greater than 30% μm 2 , or greater than 35% μm 2 , or greater than 40% μm 2 , or greater than 45% μm 2 , or greater than 50% μm 2 , or greater than 55% μm 2 , or at 30% μm 2 Up to 65% μm 2 within the range of 35% μm 2 Up to 60% μm 2 within the range of 40% μm 2 Up to 55% μm 2 within the range.

[0075] In some embodiments, the relative refractive index of the trench cladding region 34 is Δ3 or Δ 3min In the range of -0.50% to 0.20%, and the trench volume is greater than 30% μm 2 , or greater than 35% μm 2 , or greater than 40% μm 2 , or greater than 45% μm 2 , or greater than 50% μm 2 , or greater than 55% μm 2 , or at 30% μm 2 Up to 65% μm 2 within the range of 35% μm 2 Up to 60% μm 2 within the range of 40% μm 2 Up to 55% μm 2 within the range.

[0076] The relative refractive index of the outer cladding region 16 is Δ4 or Δ 4max The relative refractive index Δ4 is ​​preferably constant or approximately constant within the range of 0.005% to 0.100%, or within the range of 0.010% to 0.050%, or within the range of 0.010% to 0.030%, or within the range of 0.015% to 0.030%, or within the range of 0.015% to 0.025%.

[0077] The inner radius r3 of the outer cladding region 16 has the values ​​specified above. The outer radius r4 of the outer cladding region 16 is in the range of 57.5 μm to 67.5 μm, or in the range of 60.0 μm to 65.0 μm, or in the range of 61.0 μm to 64.0 μm, or between 62 μm and 63 μm, or about 62.5 μm. In other embodiments, the outer radius r4 of the outer cladding region 16 is less than 60.0 μm, or less than 55.0 μm, or in the range of 45.0 μm to 60 μm, or in the range of 47.5 μm to 57.5 μm, or in the range of 50 μm to 55 μm. The thickness r4-r3 of the outer cladding region 16 is 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.

[0078] Optical fiber coating. The transmittance of light through an optical fiber is highly dependent on the properties of the coating applied to the glass fiber. The coating typically includes a primary coating 22 and a secondary coating 24, wherein the secondary coating surrounds the primary coating and the primary coating contacts the glass fiber (which includes a central core region surrounded by a cladding region). The secondary coating is a harder material than the primary coating (higher Young's modulus (e.g., greater than 1400 MPa)) and is designed to protect the glass fiber from damage caused by wear or external forces generated during processing, handling and installation of the optical fiber. The primary coating is a softer material than the secondary coating (lower Young's modulus (e.g., less than 1 MPa)) and is designed to buffer or dissipate the stress generated by the force applied to the outer surface of the secondary coating. Stress dissipation within the primary coating weakens the stress and minimizes the stress reaching the glass fiber. The primary coating is particularly important in dissipating the stress generated by microbending encountered when the optical fiber is laid in the cable. It is necessary to minimize the microbending stress transmitted to the glass fiber because the microbending stress produces local disturbances in the refractive index distribution of the glass fiber. Local refractive index perturbations result in intensity loss of light transmitted through the glass fiber. By dissipating stress, primary coatings minimize microbending-induced intensity losses.

[0079] The primary coating 22 preferably has a higher refractive index than the cladding region of the glass fiber to allow it to strip errant optical signals from the core region. During thermal and hydrolytic aging, the primary coating should maintain adequate adhesion to the glass fiber but be strippable from the glass fiber for splicing purposes.

[0080] The primary and secondary coatings are typically formed by applying a curable coating composition as a viscous liquid to a glass fiber and curing. The optical fiber 10 may also include a tertiary coating (not shown) surrounding the secondary coating. The tertiary coating may include a pigment, ink, or other colorant to mark the optical fiber for identification purposes and typically has a Young's modulus similar to that of the secondary coating.

[0081] Primary coating composition. Primary coating 22 is a 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, a low pull-out force, and a strong cohesive force. The curable primary coating composition further enables the formation of a primary coating that has clean strippability and high tolerance to defect formation during a stripping operation. The low pull-out force facilitates clean stripping of the primary coating with minimal residue, and the strong cohesive force inhibits the generation and propagation of defects in the primary coating when it is subjected to a stripping force.

[0082] The primary coating is a cured product of a radiation curable primary coating composition, which includes an oligomer, a monomer, a photoinitiator, and optional additives. The following disclosure describes an oligomer for a radiation curable primary coating composition, a radiation curable primary coating composition containing at least one of the oligomers, a cured product of a radiation curable primary coating composition containing 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.

[0083] The oligomer preferably includes a polyether urethane diacrylate compound or a combination of a polyether urethane diacrylate compound and a di-adduct compound. In one embodiment, the polyether urethane diacrylate compound has a linear molecular structure. In one embodiment, the oligomer is formed by the reaction between a diisocyanate compound, a polyol compound and a hydroxy acrylate compound, wherein the reaction produces a polyether urethane diacrylate compound as a main product (majority product) and a di-adduct compound as a by-product (minority product). When the isocyanate group of the diisocyanate compound reacts with the alcohol group of the polyol, the reaction forms a carbamate connection. The hydroxy acrylate compound reacts with the isocyanate group of the quenching residue, and the isocyanate group is present in the composition formed by the reaction of the diisocyanate compound and the polyol compound. As used herein, the term quenching refers to the conversion of the isocyanate group by chemically reacting with the hydroxyl group of the hydroxy acrylate compound. The residual isocyanate groups are quenched with a hydroxy acrylate compound to convert the terminal isocyanate groups into terminal acrylate groups.

[0084] The diisocyanate compound, the hydroxy acrylate compound and the polyol are combined and reacted simultaneously, or combined and reacted sequentially (in any order). In one embodiment, the oligomer is formed by reacting the diisocyanate compound with the hydroxy acrylate compound, and reacting the resulting product composition with the polyol. In another embodiment, the oligomer is formed by reacting the diisocyanate compound with the polyol compound, and reacting the resulting product composition with the hydroxy acrylate compound.

[0085] The oligomer is formed by the reaction of a diisocyanate compound, a hydroxy acrylate compound and a polyol, wherein during the reaction, the molar ratio of the diisocyanate compound to the hydroxy acrylate compound to the polyol is n:m:p. n, m and p are referred to herein as the mole number or molar ratio of diisocyanate, hydroxy acrylate and 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 scaled proportionally. For example, the molar ratio n:m:p = 4.0:3.0:2.0 is equivalent to the molar ratio n:m:p = 2.0:1.5:1.0.

[0086] The curable primary coating composition further comprises one or more monomers. One or more monomers are selected to be compatible with the oligomer, to control the viscosity of the primary coating composition, to facilitate processing, and / or to affect the physical or chemical properties of the coating formed as the cured product of the primary coating composition. These monomers include radiation-curable monomers such as ethylenically unsaturated compounds, ethoxylated acrylates, ethoxylated alkylphenol monoacrylates, propylene oxide acrylates, n-propylene oxide acrylates, isopropylene oxide acrylates, monofunctional acrylates, monofunctional aliphatic epoxy acrylates, multifunctional acrylates, multifunctional aliphatic epoxy acrylates, and combinations thereof.

[0087] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers with one or more acrylate or methacrylate groups. Alkoxylated monomers are monomers including one or more alkyleneoxy groups, wherein the alkyleneoxy group has the form of -OR-, and R is a straight or branched alkylene group. Examples of alkyleneoxy groups include ethyleneoxy (-O-CH2-CH2-), n-propyleneoxy (-O-CH2-CH2-CH2-), isopropyleneoxy (-O-CH2-CH(CH3)-, or -CH2-O-CH(CH3)-CH2-) and the like. As used herein, the degree of alkoxylation refers to the number of alkyleneoxy groups in the monomer. In one embodiment, the alkyleneoxy groups are continuously bonded in the monomer.

[0088] In some embodiments, the primary coating composition includes a compound of the form R4—R5—O—(CH(CH3)CH2—O) q—alkoxylated monomers of C(O)CH═CH2, wherein R4 and R5 are aliphatic, aromatic or a mixture of the two, and q=1 to 10, or R4-O-(CH(CH3)CH2-O) q -C(O)CH=CH2, wherein C(O) is a carbonyl group, R1 is aliphatic or aromatic, and q=1 to 10.

[0089] In some embodiments, the monomer component of the primary coating composition includes a multifunctional (meth) acrylate. The multifunctional ethylenically unsaturated monomer includes a multifunctional acrylate monomer and a multifunctional methacrylate monomer. The multifunctional acrylate is an acrylate having two or more polymerizable acrylate moieties per molecule, or having three or more polymerizable acrylate moieties per molecule.

[0090] In some embodiments, the primary coating composition includes an N-vinyl amide, such as N-vinyl lactam or N-vinyl pyrrolidone or N-vinyl caprolactam.

[0091] In addition to the curable monomer and the curable oligomer, the curable primary coating composition also includes a polymerization initiator. The polymerization initiator helps to initiate the polymerization process associated with the curing of the coating composition to form a coating. The polymerization initiator includes a thermal initiator, a chemical initiator, an electron beam initiator and a photoinitiator. The photoinitiator includes a ketone photoinitiator and / or a phosphine oxide photoinitiator. When used to cure the coating composition, the amount of the photoinitiator present is enough to achieve rapid radiation curing.

[0092] The curable primary coating composition optionally includes one or more additives. The additives include adhesion promoters, reinforcing agents, antioxidants, catalysts, stabilizers, brighteners, property enhancers, amine synergists, waxes, lubricants and / or slip agents. Some additives can be used to control the polymerization process, thereby affecting the physical properties (e.g., modulus, glass transition temperature) of the polymerized product formed by the coating composition. Other additives affect the integrity of the cured product of the primary coating composition (e.g., protecting it from depolymerization or oxidative degradation).

[0093] Secondary coating - composition. Secondary coating 24 is the cured product of a curable secondary coating composition including monomers, photoinitiators, optional oligomers, and optional additives. The present disclosure describes optional oligomers for radiation-curable secondary coating compositions, 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.

[0094] The second coating is formed as a cured product of a radiation-curable second coating composition, which includes a monomer component having one or more monomers. The monomer preferably includes an ethylenically unsaturated compound. In one embodiment, the secondary coating is a radiation-cured product of a secondary coating composition containing a polyurethane acrylate monomer.

[0095] The monomer includes a functional group as a polymerizable group and / or a group that promotes or can be cross-linked. The monomer is a monofunctional monomer or a polyfunctional monomer. In a combination of two or more monomers, the constituent monomers can be a monofunctional monomer, a polyfunctional monomer, or a combination of a monofunctional monomer and a polyfunctional monomer. In one embodiment, the monomer component of the curable secondary coating composition includes an ethylenically unsaturated monomer. Suitable functional groups of ethylenically unsaturated monomers include, but are not limited to, (meth) acrylates, acrylamides, N-vinylamides, styrene, vinyl ethers, vinyl esters, acidic esters and combinations thereof.

[0096] In one embodiment, the monomer component of the curable secondary coating composition includes ethylenically unsaturated monomers. The monomer includes a functional group as a polymerizable group and / or a group that promotes or can be cross-linked. The monomer is a monofunctional monomer or a multifunctional monomer. In a combination of two or more monomers, the constituent monomers can be a monofunctional monomer, a multifunctional monomer, or a combination of a monofunctional monomer and a multifunctional monomer. Suitable functional groups of ethylenically unsaturated monomers include, but are not limited to, (meth) acrylates, acrylamides, N-vinylamides, styrene, vinyl ethers, vinyl esters, acidic esters and combinations thereof.

[0097] Representative radiation-curable ethylenically unsaturated monomers include alkoxylated monomers with one or more acrylate or methacrylate groups. Alkoxylated monomers are monomers including one or more alkylene oxides, wherein the alkylene oxide has the form of -OR-, and R is a straight or branched hydrocarbon. Examples of alkylene oxides include ethylene oxide (-OCH2-CH2-), n-propylene oxide (-O-CH2-CH2-CH2-), isopropylene oxide (-O-CH2-CH(CH3)-) and the like. As used herein, the degree of alkoxylation refers to the number of alkylene oxides in the monomer. In one embodiment, the alkylene oxides are continuously bonded in the monomer.

[0098] Multifunctional ethylenically unsaturated monomers for use in the curable secondary coating composition include, but are not limited to, alkoxylated bisphenol A diacrylates, such as ethoxylated bisphenol A diacrylates, having a degree of alkoxylation of 2 or greater. The monomer component of the secondary coating composition may include ethoxylated bisphenol A diacrylates having a degree of ethoxylation of 2 to about 30 or propoxylated bisphenol A diacrylates having a degree of propoxylation of 2 or greater, for example, 2 to about 30; alkoxylated and unalkoxylated methylolpropane multiacrylates, such as ethoxylated trimethylolpropane triacrylates having a degree of ethoxylation of 3 or greater.

[0099] The curable secondary coating composition also includes a photoinitiator and optionally includes additives such as, as described above in conjunction with the curable primary coating composition, (multiple) antioxidants, (multiple) fluorescent brighteners, (multiple) amine synergists, (multiple) adhesion promoters, (multiple) catalysts, (multiple) carriers or surfactants and (multiple) stabilizers.

[0100] In the foregoing embodiments, a tertiary layer (eg, ink layer) optionally surrounds or is directly adjacent to the secondary coating.

[0101] Fiber preform. In production, an optical fiber is drawn from a preform. The preform is a dense glass monolith with a typical diameter of about 27 cm and a typical length of about 200 cm. The preform includes a central core region surrounded by an annular cladding region. The composition of the core and cladding regions of the preform corresponds to the composition of the core and cladding regions of the optical fiber drawn from the preform. The diameter of the core region of the preform and the thickness of the cladding region of the preform are proportional to the core diameter and cladding thickness of the optical fiber drawn from the preform. The core region and / or cladding region of the preform may include multiple concentric layers that differ in dopant type or dopant concentration to provide an optical fiber having a desired refractive index profile (such as the relative refractive index profile described herein).

[0102] Silica and doped silica for the core and cladding regions of the optical fiber preform can be produced by methods known in the art. Suitable methods include flame combustion, flame oxidation, flame hydrolysis, OVD (external vapor deposition), IVD (internal vapor deposition), VAD (vapor axial deposition), double crucible method, rod-in-tube procedure, cane-in-soot method and doped deposited silica process. Various CVD (chemical vapor deposition) and plasma enhanced CVD processes are known and suitable for producing silica or doped silica.

[0103] The formation of silicon dioxide occurs by reaction or decomposition of silicon dioxide precursors. Suitable silicon dioxide precursors include OMCTS (octamethylcyclotetrasiloxane) and SiCl4. Doping is done with doping precursors. Doping precursors can be introduced together with silicon dioxide precursors in the deposition process, or used to treat silicon dioxide bodies formed by silicon dioxide precursors. Preferred doping precursors include halogen-containing gases. Suitable precursors for bromine-doped silicon dioxide include SiBr4. Suitable precursors for chlorine doping include Cl2, SiCl4, Si2Cl6, Si2OCl6, SiCl3H and CCl4. Suitable precursors for fluorine doping include F2, CF4 and SiF4. Silicon dioxide precursors and / or doping precursors are preferably provided to the deposition process as gases. Gas phase silicon dioxide precursors or gas phase doping precursors are supplied undilutedly or in combination with inert diluent gases (e.g., He, N2, Ar).

[0104] Fiber drawing process. In a continuous optical fiber manufacturing process, a glass fiber is drawn from a heated preform and sized to a target diameter (typically 125 μm, corresponding to r4=62.5 μm). The glass fiber is then cooled and directed 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, there are two possible process options. In one process option (wet-to-dry process), the liquid primary coating composition is cured to form a cured 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 cured secondary coating. In a second process option (wet-to-wet process), a liquid secondary coating composition is applied to the liquid primary coating composition, and the two liquid coating compositions are cured simultaneously to provide cured primary and secondary coatings. After the optical fiber leaves the coating system, the optical fiber is collected and stored at room temperature. The collection of the optical fiber typically involves winding the optical fiber onto a spool and storing the spool.

[0105] 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 cured tertiary coating. Typically, the tertiary coating is an ink layer used to mark the optical fiber for identification purposes, and has a composition including a pigment, and is similar to the secondary coating in other respects. The tertiary coating is applied to the secondary coating and cured. When the tertiary coating is applied, the secondary coating is typically already cured. 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 optical fiber is collected, and the tertiary coating composition is applied and cured in a separate offline process to form a tertiary coating.

[0106] The wavelength of curing radiation is an infrared wavelength, a visible wavelength or an ultraviolet wavelength (UV). Representative wavelengths include wavelengths in the range of 250nm to 1000nm, or in the range of 250nm to 700nm, or in the range of 250nm to 450nm, or in the range of 275nm to 425nm, or in the range of 300nm to 400nm, or in the range of 320nm to 390nm, or in the range of 330nm to 380nm, or in the range of 340nm to 370nm. Curing can be completed with a light source including a lamp source (e.g., a mercury lamp), an LED source (e.g., a UVLED, a visible light LED or an infrared LED) or a laser source.

[0107] Each of the primary, secondary, and tertiary compositions may be cured using any of the wavelengths and any of the light sources described above. The same wavelength or source may be used to cure each of the primary, secondary, and tertiary compositions, or different wavelengths and / or different sources may be used to cure the primary, secondary, and tertiary compositions. Curing of the primary, secondary, and tertiary compositions may be accomplished using a single wavelength or a combination of two or more wavelengths.

[0108] To improve process efficiency, it is desirable to increase the drawing speed of the fiber along the process path extending from the preform to the collection point. However, as the drawing speed increases, the curing speed of the coating composition must increase. The coating compositions disclosed herein are compatible with fiber drawing processes operating at drawing speeds greater than 35 m / s, or greater than 40 m / s, or greater than 45 m / s, or greater than 50 m / s, or greater than 55 m / s, or greater than 60 m / s, or greater than 65 m / s, or greater than 70 m / s.

[0109] A reduced diameter optical fiber 10 is disclosed having an optical device matched to a single mode optical fiber, compatible with low cost manufacturing, and having an optical device with good macrobend and microbend performance and puncture resistance. In some embodiments, the optical fiber 10 has a groove-assisted design, wherein the groove has a triangular shape and the groove volume is greater than 30% μm 2 , and more specifically at 30% Δμm 2 and 70% Δμm 2, wherein the optical fiber has a mode field diameter (MFD) greater than 9.0 microns at 1310 nm and exhibits optical fiber properties that conform to ITU-G.657.A2 specifications. In some embodiments, the glass diameter (2r4) is less than 110 microns. In other embodiments, the glass diameter is less than 100 microns or less than 85 microns. In one embodiment, the glass diameter is between 124 μm and 126 μm, or about 125 μm. The optical fiber has a zero dispersion wavelength between 1300 nm and 1324 nm, a cable cutoff wavelength less than 1260 nm, and a macrobending loss of less than 0.5 dB / turn for a 15 mm mandrel diameter at 1550 nm, a macrobending loss of less than 0.1 dB / turn for a 20 mm mandrel diameter, and a macrobending loss of less than 0.003 dB / turn for a 30 mm mandrel diameter. In some embodiments, the optical fiber 10 exhibits a puncture resistance greater than 20 g. In other embodiments, the optical fiber 10 exhibits a puncture resistance greater than 30 g. In yet other embodiments, the optical fiber 10 exhibits a puncture resistance greater than 40 g.

[0110] In order to provide a cable with a smaller diameter and with a high fiber density, an optical fiber with a smaller outer diameter is needed. In some embodiments, the optical fiber 10 has an outer coating diameter (2r6) less than or equal to 185 microns. In another embodiment, the optical fiber 10 has an outer coating diameter less than or equal to 180 microns. In yet another embodiment, the optical fiber 10 has an outer coating diameter less than or equal to 175 microns. In yet other embodiments, the optical fiber 10 has an outer coating diameter less than or equal to 170 microns.

[0111] In addition, in cables where the optical fibers are closely packed, the optical fibers are more sensitive to microbending, especially at lower temperatures (e.g., <-10°C). In addition, it is important to have an optical fiber with a mode field diameter (MFD) that matches that of a standard single-mode optical fiber resulting in lower coupling losses. In some embodiments, the optical fiber 10 has optical properties that comply with ITU-G.652.D and ITU-G.657.A2 specifications and has a mode field diameter (MFD) greater than or equal to 9.0 microns at 1310 nm. In another embodiment, the optical fiber has optical properties that comply with ITU-G.652.D and ITU-G.657.A2 specifications and has a mode field diameter (MFD) greater than or equal to 9.1 microns at 1310 nm. In yet other embodiments, the optical fiber has optical properties that comply with ITU-G.652.D and ITU-G.657.A2 specifications and has a mode field diameter (MFD) greater than or equal to 9.2 microns at 1310 nm. The optical fiber exhibits an MFD greater than or equal to 9.0 microns at 1310 nm, a cable cut-off wavelength less than 1260 nm, a zero dispersion wavelength between 1300 nm and 1324 nm, a macrobending loss of less than 0.5 dB / turn for one turn around a core having a diameter of 15 mm at 1550 nm, a macrobending loss of less than 0.1 dB / turn for one turn around a core having a diameter of 20 mm at 1550 nm, and a macrobending loss of less than 0.003 dB / turn for one turn around a core having a diameter of 30 mm at 1550 nm.

[0112] Optical fiber 10 has a trench-assisted design, which includes a core region having a radius r1, a maximum core refractive index Δ 1max The germanium-doped core region 30, the inner cladding region 32 having an inner cladding radius r2 and an average refractive index Δ2, and the trench radius r3 and the minimum trench refractive index Δ 3min and an outer cladding region 16 having a radius r4 and an average refractive index Δ4.

[0113] In the present disclosure, a trench assisted profile has been disclosed having a core (core refractive index Δ1), an inner cladding region (inner cladding refractive index Δ2), a triangular or monotonically decreasing (with increasing radial coordinates) trench region (trench refractive index Δ3) and an outer cladding region (outer cladding refractive index Δ4), wherein Δ1>Δ4>Δ2>Δ 3,min The difference between Δ4-Δ2 is greater than 0.005%, or greater than 0.010%, or greater than 0.015%, or greater than 0.020%, or less than 0.035%, or within the range of 0.005% to 0.035%, or within the range of 0.005% to 0.025%, or within the range of 0.010% to 0.020%.

[0114] In some embodiments, the outer cladding region is doped with chlorine at a chlorine concentration greater than 0.05 wt%, or greater than 0.07 wt%, or greater than 0.10 wt%, or greater than 0.15 wt%, or greater than 0.2 wt%, or greater than 0.3 wt%. In some embodiments, the chlorine doping of the outer cladding region is performed using silicon tetrachloride as a dopant gas or precursor during consolidation or sintering of the outer cladding soot into glass. In other embodiments, the chlorine doping of the outer cladding region is performed using a gas mixture of chlorine gas and carbon monoxide gas during consolidation or sintering of the outer cladding soot to form the outer cladding region, wherein the concentration of the carbon monoxide gas in the gas mixture is greater than 1000 ppm, or greater than 1500 ppm, or greater than 2000 ppm, or greater than 2500 ppm, or greater than 5000 ppm.

[0115] Example

[0116] The optical fiber 10 is further described by the following modeling example. Figure 2-Figure 4 Table 1 shows that with Δ4>Δ2, with inner cladding region, trench volume at 30% Δμm 2 and 60% Δμm 2 The cable has a triangular groove between 1300nm and 1324nm, an MFD greater than 9.2 microns at 1310nm, a zero dispersion wavelength between 1300nm and 1324nm, a cable cut-off wavelength less than 1260nm, macrobending losses less than 0.5dB / turn for a 15mm mandrel diameter at 1550nm, macrobending losses less than 0.1dB / turn for a 20mm mandrel diameter at 1550nm, and macrobending losses less than 0.0034dB / turn for a 30mm mandrel diameter at 1550nm.

[0117] Table 1: Distribution parameters for modeling examples Example 1 Example 2 Example 3 picture 2 3 4 <![CDATA[Δ 1max (%)]]> 0.3435 0.345 0.35 Core α 12 12 6 <![CDATA[r1(μm)]]> 4.575 4.7 5 <![CDATA[Δ2(%)]]> 0 0 0 <![CDATA[r2(μm)]]> 10 9 8 <![CDATA[r3(μm)]]> 20 18 17 <![CDATA[Δ 3min (%)]]> -0.2 -0.4 -0.4 <![CDATA[Slot volume (%Δμm 2 )]]> 35 54 50 <![CDATA[r4(μm)]]> 62.5 62.5 62.5 <![CDATA[Δ4(%)]]> 0.01 0.015 0.015

[0118] Table 2: Optical properties of simulation examples Example 1 Example 2 Example 3 MFD at 1310nm (μm) 9.15 9.15 9.15 Zero dispersion wavelength(nm) 1312 1307 1308 Cable cut-off wavelength (nm) 1235 1235 1235 15mm macrobending loss (dB / turn) 0.25 0.09 0.09 20mm macrobending loss (dB / turn) 0.05 0.02 0.03 30mm macrobending loss (dB / turn) 0.0028 0.0014 0.0012 Attenuation coefficient at 1310nm (dB / km) <0.33 <0.33 <0.33 Attenuation coefficient at 1383nm (dB / km) <0.33 <0.33 <0.33 Attenuation coefficient at 1550nm (dB / km) <0.19 <0.19 <0.19

[0119] The corresponding parameters of the optical fibers CEx.1, CEx.2 and CEx.3 used for comparison when there is no up-doping in the outer cladding region are shown in Table 3 below:

[0120] Table 3: Comparison examples CEx.1 CEx.2 CEx.3 <![CDATA[Δ 1max (%)]]> 0.333 0.32 0.335 Core α 12 12 6 <![CDATA[r1(μm)]]> 4.6 4.425 4.7 <![CDATA[Δ2(%)]]> 0 0 0 <![CDATA[r2(μm)]]> 10 8 7.5 <![CDATA[r3(μm)]]> 21.5 17.6 17.5 <![CDATA[Δ 3min (%)]]> -0.2 -0.4 -0.4 <![CDATA[r4(μm)]]> 62.5 62.5 62.5 <![CDATA[Δ4(%)]]> 0 0 0 MFD at 1310nm (μm) 9.15 9.15 9.15 Cable cut-off wavelength (nm) 1235 1235 1235 15mm macrobending loss (dB / turn) 0.23 0.16 0.17 20mm macrobending loss (dB / turn) 0.018 0.06 0.07 30mm macrobending loss (dB / turn) 0.015 0.0018 0.0015

[0121] The data shown in Tables 2 and 3 illustrate that at bend diameters of 15 mm, 20 mm and 30 mm, up-doping of the outer cladding region results in a significant reduction in macrobending losses.

[0122] The use of SiCl4 in chlorine doping of the outer cladding region reduces the concentration of non-bridging oxygen defect centers in the outer cladding, wherein the concentration of non-bridging oxygen defects in the outer cladding region is less than 4x10 15 / cm 3 . In one embodiment, the reduction in defect concentration in the cladding is reflected in a reduction in the peak time (TTP) of the hydrogen exposure test (1% H2 exposure at 23°C) from about 115 hours for a silica cladding prepared using the OVD process to less than 70 hours. A similar reduction in peak time can also be achieved by using carbon monoxide with chlorine. Therefore, by treating the outer cladding with carbon monoxide gas and gas mixture, the treatment process may take, for example, about 70-130 hours for applying the dopant after the optical fiber is drawn and wound onto a bobbin. Similarly, according to one example, a chlorine dopant can be applied to the outer cladding, which may take at least 115 hours.

[0123] According to one embodiment, the optical fiber has a total attenuation of less than 0.32 dB / km at a wavelength of 1310 nm and less than 0.13 dB / km at a wavelength of 1550 nm. As is well known in the art, the total attenuation is measured at wavelengths of 1310 nm and 1550 nm using an optical time domain reflectometer (OTDR).

[0124] Puncture resistance

[0125] Puncture resistance measurement was disclosed by Glaesemann and Clark [GS Glaesemann and DA Clark, "Quantifying the Puncture Resistance of Optical Fiber Coatings", Proc. 52nd IWCS, pp. 237-245 (1993)] as a measure for quantifying the ability of a coating to protect an underlying glass surface from mechanical damage. The Glaesemann article discloses a method for measuring this property and teaches that the puncture resistance of a coating system comprising a primary coating and a secondary coating depends linearly on the secondary coating modulus E s The product of the cross-sectional area of ​​the secondary coating(s).

[0126] Our model assumes that the secondary coating is a thick-walled ring, which is reasonable because the ratio of the thickness of the secondary coating to the average radius of the secondary coating is on the order of 15 / 150 ≈ 10%. Then, the hoop stress It is given by the Lamé equation as follows: where the i and o subscripts refer to the inner and outer surfaces of the secondary coating, respectively. The deformation of the secondary coating caused by a foreign body (such as the diamond wedge indenter used by Glaesemann) is a local force that generates a pressure p0 on the outer surface of the secondary coating that is much greater than the pressure p0 exerted on the inner surface of the secondary coating by the low modulus primary coating. i . Hoop stress is r = r i The pressure p on the inner surface of the secondary coating is maximum. i In the limit of zero, the maximum hoop stress is given by: in, is the cross-sectional area of ​​the secondary coating ring. Then, the puncture load is related to E s / σ h,max ∝E s A s Proportional.

[0127] The puncture resistance is equal to the puncture load applied to the optical fiber. In the limit where the thickness of the primary coating becomes very small, the pressure applied to the inner surface of the secondary coating is due to the glass, p i The contribution to the hoop stress cannot be neglected. Then, the hoop stress is given by σ h =-p o Given, this stress is a constant value that depends on the indentation load and the surface area of ​​the indenter. The full expression for puncture resistance (in g) is P R =P0+C1E s A s , where E s is the Young's modulus of the secondary coating (in MPa), and the coefficients P0 and C1 have approximately 10.03 g and 1.31 g / MPa / mm, respectively. 2 The value of .

[0128] The primary coating has an in-situ modulus preferably in the range of 0.05 MPa to 0.30 MPa. The in-situ modulus measurement may include forming the primary coating on a glass fiber of a certain diameter. The in-situ modulus measurement may be performed on a Rheometrics DMTA IV dynamic mechanical testing equipment at room temperature (21°C) at 9e -6 The test is performed for a period of forty-five (45) minutes at a constant strain of 1 / s. The gauge length can be set to a distance such as 15 millimeters. The force and length changes can be recorded and used to calculate the in-situ modulus of the primary coating. An example of an in-situ modulus measurement is disclosed in U.S. Patent No. 11,036,000, which is incorporated herein by reference.

[0129] The secondary coating has a Young's modulus greater than 1600 MPa. The Young's modulus can be measured on a film formed by the cured coating composition forming the secondary coating. The Young's modulus can be measured on a film sample using an MTS Sintech tensile test instrument according to the procedure in ASTM standard D882-97. The Young's modulus is defined as the steepest slope at the starting point of the stress-strain curve. The film can be tested at an elongation such as 2.5 cm / min and an additional specification length such as 5.1 cm. An example of a Young's modulus test measurement is disclosed in U.S. Patent Application Publication No. 2018 / 0127593, which is incorporated herein by reference.

[0130] Based on considerations of microbending attenuation loss, puncture resistance, bending losses, and the desire for smaller fiber diameters, a primary coating having an in-situ modulus of less than 0.50 MPa is preferred, such as an in-situ modulus of 0.05 MPa to 0.30 MPa or 0.10 MPa to 0.30 MPa, and a thickness r5-r4 of 5 microns to 30 microns, or 10 microns to 25 microns, or 10 microns to 22 microns, or 11 microns to 20 microns. It is further preferred that the secondary coating has a Young's modulus greater than 1400 MPa, or greater than 1600 MPa, or greater than 1800 MPa, or greater than 2000 MPa, such as a Young's modulus in the range of 1400 MPa to 3000 MPa or in the range of 1600 MPa to 2600 MPa, and a thickness r6-r5 in the range of 5 microns to 25 microns, or in the range of 8 microns to 20 microns, or in the range of 8 microns to 17 microns, or in the range of 9 microns to 16 microns.

[0131] An optical fiber having a coating system including a primary coating and a secondary coating disclosed herein has a puncture resistance greater than 15 g, or greater than 20 g, or greater than 30 g, or greater than 40 g, or in a range of 15 g to 50 g, or in a range of 20 g to 45 g, or in a range of 25 g to 40 g.

[0132] The embodiments described herein are preferred and / or illustrative but not restrictive. Various modifications are within the purview and scope of the appended claims.

Claims

1. An optical fiber, comprising: A core region having an outer radius r1 in the range of 4.0 μm to 8.0 μm and a maximum relative refractive index Δ 1max A relative refractive index distribution Δ1 in the range of 0.20% to 0.50%; a cladding region surrounding the core region and directly adjacent to the core region, the cladding region comprising: A trench cladding region, the trench cladding region surrounding the core region, the trench cladding region having a triangular shape, an inner radius r2, an outer radius r3, a minimum relative refractive index Δ 3min Relative refractive index Δ3 greater than -0.60% and less than 0.00%, and greater than 30% μm 2 The groove volume; and an outer cladding region surrounding and directly adjacent to the trench cladding region, the outer cladding region having an outer radius r4 and a relative refractive index D4 in the range of 0.01% to 0.06% and a chlorine concentration greater than 1000 ppm; wherein the optical fiber has a mode field diameter greater than or equal to 9.0 microns at 1310 nm, a cable cutoff wavelength less than 1260 nm, and a zero dispersion wavelength between 1300 nm and 1324 nm; wherein the optical fiber has a macrobending loss of less than 0.5 dB / turn at 1550 nm according to a mandrel winding test using a mandrel having a diameter of 15 mm; and According to a mandrel winding test using a mandrel with a diameter of 30 mm, the optical fiber has a macrobending loss of less than 0.003 dB / turn at 1550 nm.

2. The optical fiber according to claim 1, wherein The chlorine concentration in the outer cladding region is greater than 2000 ppm.

3. The optical fiber according to claim 1 or 2, wherein: The chlorine concentration in the outer cladding region is greater than 3000 ppm.

4. The optical fiber according to any one of claims 1 to 3, wherein: The optical fiber has a mode field diameter greater than or equal to 9.1 microns at 1310 nm.

5. The optical fiber according to any one of claims 1 to 4, wherein The optical fiber has a mode field diameter greater than or equal to 9.2 microns at 1310 nm.

6. The optical fiber according to any one of claims 1 to 5, wherein: The trench volume of the trench cladding region is greater than 45% D μm 2 .

7. The optical fiber according to any one of claims 1 to 6, wherein: The cladding region further includes an inner cladding region having a relative refractive index D2, the inner cladding region surrounding the core region and directly adjacent to the core region, the trench cladding region surrounding the inner cladding region and directly adjacent to the inner cladding region, and wherein the difference D4-D2>0%.

8. The optical fiber according to claim 7, wherein: The difference D4-D2>0.015%.

9. The optical fiber according to claim 7 or 8, wherein D2 = 0%.

10. The optical fiber of any one of claims 1-9, further comprising a primary coating surrounding and directly adjacent to the cladding region, and a secondary coating surrounding and directly adjacent to the primary coating, wherein the outer radius of the secondary coating is less than or equal to 105.0 microns.

11. The optical fiber of any one of claims 1-10, further comprising a primary coating surrounding and directly adjacent to the cladding region, and a secondary coating surrounding and directly adjacent to the primary coating, wherein the outer radius of the secondary coating is less than or equal to 95.0 microns.

12. The optical fiber of any one of claims 1-11, further comprising a primary coating surrounding and directly adjacent to the cladding region, and a secondary coating surrounding and directly adjacent to the primary coating, the outer radius of the secondary coating being less than or equal to 90.0 microns.

13. The optical fiber according to any one of claims 1 to 12, wherein: The chlorine doping of the outer cladding region is achieved by using silicon tetrachloride as doping gas during sintering of the outer cladding soot into glass.

14. The optical fiber according to any one of claims 1 to 13, wherein: The chlorine doping of the outer cladding region is achieved by using a mixed gas comprising chlorine and carbon monoxide during sintering of the outer cladding soot into glass.

15. The optical fiber of claim 14, wherein: The concentration of the carbon monoxide in the gas mixture is greater than 1000 ppm.

16. The optical fiber of claim 14, wherein: The concentration of the carbon monoxide in the gas mixture is greater than 1 mol %.

17. The optical fiber according to any one of claims 10 to 16, wherein The outer radius r4 of the outer cladding region is between 62 microns and 63 microns.

18. The optical fiber according to any one of claims 10 to 16, wherein The outer radius r4 of the outer cladding region is between 43 microns and 62 microns.

19. The optical fiber of any one of Claims 1-18, wherein the optical fiber has a puncture resistance greater than 30 g.

20. The optical fiber of any one of claims 1 to 19, wherein the optical fiber has an attenuation of less than 0.32 dB / km at 1310 nm and less than 0.18 dB / km at 1550 nm.

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