Single-mode fiber optic cable

Abstract

Each embodiment of the present disclosure includes a single-mode ultra-low loss optical fiber (10) having a low trench volume. The single-mode optical fiber has a first core region (16) and a core region surrounding and immediately adjacent to the first core region, the core region having a volume V of 14% Δμm. 2 and a cladding region (20) surrounding the core region, and the optical fiber has a cable cutoff wavelength of less than 1260 nm, a mode field diameter at 1310 nm of 8.6 μm to 9.7 μm, a mode field diameter at 1550 nm of 9.9 μm to 11 μm, and an attenuation at 1550 nm of 0.17 dB / km or less.

Description

Cross-reference with related applications

[0001] This application claims priority under 35 United States Code § 119 of U.S. Provisional Patent Application No. 63 / 124,455, filed on 11 December 2020, the contents of which are hereby referenced and are considered to be part of this application. [Technical Field]

[0002] This disclosure relates to optical fibers. More specifically, this disclosure relates to single-mode optical fibers. More specifically, this disclosure relates to low-trench single-mode ultra-low-loss optical fibers. [Background technology]

[0003] Telecommunication systems, in both submarine and terrestrial applications, require optical fibers capable of transmitting signals over long distances without degradation. Optical fiber attributes such as attenuation and bending loss contribute to signal degradation. Current requirements for both submarine and terrestrial applications include improved bending performance, such as a large bending diameter (e.g., 50mm to 70mm range), while also maintaining other optical attributes suitable for such applications (e.g., mode field diameter, cable breakage, and attenuation). [Overview of the project] [Problems that the invention aims to solve]

[0004] The improvements described above are desired. Accordingly, the inventors of this application have developed a single-mode optical fiber that exhibits low bending loss at a large bending diameter. [Means for solving the problem]

[0005] The first embodiment of the present disclosure includes a single-mode optical fiber, and the optical fiber includes the following as part of its components. That is, it has an outer radius r1 where the α value is in the range of 1.5 ≤ α ≤ 10 and satisfies 2.5 μm ≤ r1 ≤ 8 μm, and shows a relative refractive index percentage profile Δ1(r) measured relative to pure silica with the unit of %. The minimum relative refractive index Δ 1MIN and the maximum relative refractive index Δ 1MAX It has, and when the relative refractive index is measured at a radius r = 2 μm, a first core region where -0.35 ≤ Δ 1MIN ≤ -0.05, which surrounds the first core region and is directly adjacent thereto, extends to an outer radius r2 that satisfies 10 μm ≤ r2 ≤ 22 μm, and shows a negative relative refractive index percentage profile Δ2(r) measured relative to pure silica with the unit of %. The minimum relative refractive index percentage Δ 2MIN is such that -0.47% ≤ Δ 2MIN ≤ -0.3%, and a second core region where the amount V is 14%Δμm 2 or less, which surrounds the core and shows a relative refractive index percentage profile Δ3(r) measured relative to pure silica with the unit of %. The minimum relative refractive index Δ 3MIN is such that -0.45% ≤ Δ 3MIN ≤ -0.2%, and a cladding region. The optical fiber has a cable cutoff of less than 1260 nm, a mode field diameter of 8.6 microns (μm) to 9.7 microns (μm) at a wavelength of 1310 nm, a mode field diameter of 9.9 microns (μm) to 11 microns (μm) at a wavelength of 1550 nm, and an attenuation of 0.17 dB / km or less at a wavelength of 1550 nm.

[0006] The second embodiment of the present disclosure may include, in the first embodiment, an aspect where the amount V of the annular second core region is 0%Δμm 2 to 9%Δμm 2 .

[0007] The third embodiment of the present disclosure is, in the first embodiment, where the amount V of the annular second core region is 4%Δμm 2 to 9%Δμm 2It is desirable to include the aspect of being such.

[0008] A fourth embodiment of the present disclosure is, in the first embodiment, the amount V of the annular second core region is 2%Δμm 2 or 7%Δμm 2 It is desirable to include the aspect of being such.

[0009] A fifth embodiment of the present disclosure is, in the first embodiment, the amount V of the annular second core region is 2%Δμm 2 or 9%Δμm 2 It is desirable to include the aspect of being such. 0010 A sixth embodiment of the present disclosure may include, in the first embodiment, an embodiment in which the optical fiber exhibits a macrobend loss of less than 0.75 dB / turn when wound around a 30 mm diameter core rod.

[0010] A seventh embodiment of the present disclosure may include, in the first embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.5 dB / turn when wound around a core rod with a diameter of 40 mm.

[0011] The eighth embodiment of the present disclosure may include, in the first embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.05 dB / turn when wound around a 50 mm diameter core rod.

[0012] The ninth embodiment of the present disclosure may include, in the first embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.005 dB / turn when wound around a 60 mm diameter core rod.

[0013] The tenth embodiment of the present disclosure may include, in the first embodiment, an aspect in which 1 ≤ r2 / r1 ≤ 9, r1 ≤ 8 μm, and r2 ≤ 20 μm.

[0014] The eleventh embodiment of the present disclosure may include a configuration in the first embodiment where 2.5 ≤ r2 / r1 ≤ 5.

[0015] The twelfth embodiment of the present disclosure may include, in the first embodiment, a configuration in which the optical fiber exhibits a zero-dispersion wavelength λ0 such that 1300 nm ≤ λ0 ≤ 1324 nm.

[0016] The thirteenth embodiment of the present disclosure may include, in the first embodiment, a configuration in which the optical fiber exhibits a microbend loss of 1 dB / km or less.

[0017] The 14th embodiment of the present disclosure includes a single-mode optical fiber, which has an α value in the range of 1.5 ≤ α ≤ 10 and extends to an outer radius r1 satisfying 2.5 μm ≤ r1 ≤ 8 μm, exhibits a relative refractive index percentage profile Δ1(r) measured relative to pure silica and expressed in units of %, with a minimum relative refractive index Δ 1MIN and maximum relative refractive index Δ 1MAX It has such that when the relative refractive index is measured at a radius r=2μm, -0.35≦Δ 1MIN The first core region is ≤ -0.05, and the surrounding ring-shaped region is directly adjacent to it, extending to an outer radius r2 satisfying 10 μm ≤ r2 ≤ 22 μm, exhibiting a negative relative refractive index percentage profile Δ2(r) measured relative to pure silica and expressed in units of %, with a minimum relative refractive index percentage Δ 2MIN -0.47% ≤ Δ 2MIN The value is ≤-0.3%, and the quantity V is 14%Δμm 2 Below is a second core region and the relative refractive index percentage profile Δ3(r) surrounding the core, measured relative to pure silica and expressed in units of %, and the minimum relative refractive index percentage Δ 3MIN -0.55% ≤ Δ 3MIN The optical fiber has a cladding region of ≤-0.3%, and the cable breakage is less than 1530 nm, the mode field diameter at 1310 nm is 8.6 microns (μm) to 9.7 microns (μm), the mode field diameter at 1550 nm is 9.9 microns (μm) to 11 microns (μm), and the attenuation at 1550 nm is 0.17 dB / km or less.

[0018] The 15th embodiment of the present disclosure is the 14th embodiment in which the amount V of the annular second core region is 0%Δμm 2 or 9%Δμm 2 It is desirable to include the aspect of being such.

[0019] The sixteenth embodiment of the present disclosure is the fourteenth embodiment, in which the amount V of the annular second core region is 4%Δμm 2 or 9%Δμm 2 It is desirable to include the aspect of being such.

[0020] The 17th embodiment of the present disclosure is the 14th embodiment in which the amount V of the annular second core region is 2%Δμm 2 or 7%Δμm 2 It is desirable to include the aspect of being such.

[0021] The eighteenth embodiment of the present disclosure is the fourteenth embodiment, in which the amount V of the annular second core region is 2%Δμm 2 or 9%Δμm 2 It is desirable to include the aspect of being such.

[0022] The 19th embodiment of the present disclosure may include, in the 14th embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.005 dB / turn when wound around a 60 mm diameter core rod.

[0023] The 20th embodiment of the present disclosure may include, in the 14th embodiment, an embodiment in which the optical fiber exhibits a macrobend loss of less than 0.75 dB / turn when wound around a 30 mm diameter core rod.

[0024] The 21st embodiment of the present disclosure may include, in the 14th embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.5 dB / turn when wound around a core rod with a diameter of 40 mm.

[0025] The 22nd embodiment of the present disclosure may include, in the 14th embodiment, a configuration in which the optical fiber exhibits a macrobend loss of less than 0.05 dB / turn when wound around a core rod with a diameter of 50 mm.

[0026] The 23rd embodiment of the present disclosure may include a configuration in the 14th embodiment where 1 ≤ r2 / r1 ≤ 9, r1 ≤ 8 μm, and r2 ≤ 20 μm.

[0027] The 24th embodiment of the present disclosure may include a configuration in the 14th embodiment where 2.5 ≤ r2 / r1 ≤ 5.

[0028] The 25th embodiment of the present disclosure may include, in the 14th embodiment, a configuration in which the optical fiber exhibits a zero-dispersion wavelength λ0 such that 1300 nm ≤ λ0 ≤ 1324 nm.

[0029] The 26th embodiment of the present disclosure may include, in the 14th embodiment, a configuration in which the optical fiber exhibits a microbend loss of 1 dB / km or less.

[0030] Various other features and advantages are explicitly stated in the detailed description that follows, and will be partially readily apparent to those skilled in the art from that description, or will be recognized by carrying out each embodiment as described in the written description and claims of this application, as well as in the attached drawings.

[0031] Both the above overview and the detailed explanations that follow are merely examples and should be understood as intended to provide an outline or framework for understanding the essence and characteristics of the patent claims.

[0032] The accompanying drawings are included for further understanding and are incorporated into and form part of this specification. The drawings illustrate selected aspects of the disclosure and, together with the descriptions, help illustrate the principles and operation of the various methods, products, and configurations contained herein. [Brief explanation of the drawing]

[0033] [Figure 1] A schematic diagram of an optical fiber according to several embodiments of the present disclosure. [Figure 2] A schematic diagram illustrating specific refractive index profiles of the optical fiber shown in Figure 1, according to several embodiments of the present disclosure. [Figure 3] A diagram illustrating the relative refractive index profiles of single-mode optical fibers according to several embodiments of the present disclosure. [Modes for carrying out the invention]

[0034] This disclosure is provided as a teaching to enable implementation and can be more readily understood by referring to the following description, drawings, specific examples, and claims. Those skilled in the art will recognize and appreciate that, in order to achieve this objective, many modifications can be made to various aspects of the embodiments described herein, and still yield favorable results. It will also become clear that some of the desired advantages of the embodiments here can be obtained by selecting some features without utilizing the remaining ones. Therefore, many modifications and alterations are possible, and in some circumstances, even desirable, and those skilled in the art will recognize that these are part of the disclosure. Thus, this disclosure should be understood as not being limited to the specific configurations, articles, apparatus, and methods disclosed, unless otherwise specified. Furthermore, it should be understood that the terms used herein are intended solely to describe specific aspects and are not intended to limit them.

[0035] In this specification and the claims attached herein, we will refer to several terms which we intend to define as having the following meanings.

[0036] The "radial direction position" or radial direction coordinate "r" refers to the radial direction position relative to the centerline of the optical fiber (r=0). The length dimension "micron (μm)" is referred to herein as micron (or microns) or micrometer. The area dimension based on microns is referred herein as square micron (micron 2 ) or square micrometer (μm) 2 It is referred to as ).

[0037] A "refractive index profile" refers to the relationship between the refractive index or relative refractive index and the waveguide fiber radius. In the case of relative refractive index profiles shown herein with stepped boundaries between adjacent core regions or between core and cladding regions, changes in the processing conditions may prevent obtaining a clear stepped boundary at the interface between adjacent regions. While the boundaries of the refractive index profile may be shown herein as a step change in refractive index, it should be understood that the actual boundaries may be rounded or otherwise deviate from a perfect step function characteristic. Furthermore, it should be understood that the value of the relative refractive index may vary depending on the radial position within the core region, each cladding region, or various combinations thereof. When the relative refractive index varies depending on the radial position of a particular region of the optical fiber (core region, each cladding region, or various combinations thereof), the relative refractive index can be expressed in terms of the actual function dependence or approximate function dependence, or in terms of the average value applicable to that region. Unless otherwise specified, when the relative refractive index of a region (the core region, any of the cladding regions, or any combination thereof) is expressed as a single value, it is understood that the relative refractive index within that region is constant or nearly constant and corresponds to that single value, or that the single value represents the average of the relative refractive index dependencies, which are not constant with respect to the radial position within that region. Whether due to design or normal manufacturing variations, the dependency of the relative refractive index to the radial position may be a sloping straight line, a curve, or otherwise non-constant.

[0038] "Relative refractive index" or "percentage of relative refractive index" is defined as follows:

[0039]

number

[0040] Here, unless otherwise specified, n(r) is the refractive index at a radial distance r from the centerline of the optical fiber, and n cΔ is the refractive index of silica at a wavelength of 1550 nm. Where used herein, unless otherwise specified, the relative refractive index is represented by Δ and its value is given in units of "%". When the refractive index of a certain region is smaller than the refractive index of silica, the relative refractive index percentage is negative and is referred to as a drop in refractive index, and unless otherwise specified, it is calculated at the point where the relative refractive index is at its maximum on the negative side. When the refractive index of a certain region is larger than the refractive index of silica, the relative refractive index percentage is positive and it can be said that the region has a higher refractive index or a positive refractive index, and unless otherwise specified, it is calculated at the point where the relative refractive index is at its maximum on the positive side. In this specification, an "up-dopant" is considered to be a doping agent that tends to raise the refractive index by one step compared to pure silica (SiO2) that has not been treated with impurities. In this specification, a "down-dopant" is considered to be a doping agent that tends to lower the refractive index compared to pure silica that has not been treated with impurities. Up dopants may be present in the optical fiber region exhibiting a negative relative refractive index if one or more other doping agents that are not up dopants are also added. Similarly, one or more other doping agents that are not up dopants may be present in the optical fiber region exhibiting a positive relative refractive index. Down dopants may be present in the optical fiber region exhibiting a positive relative refractive index if one or more other doping agents that are not down dopants are also added. Similarly, one or more other doping agents that are not down dopants may be present in the optical fiber region exhibiting a negative relative refractive index. In one embodiment, the glass that has not been treated with impurities added by doping agents is pure silica glass. If the glass that has not been treated with doping agents to add impurities is pure silica glass, examples of up-dopant materials include chlorine (Cl), bromine (Br), germanium (Ge), aluminum (Al), phosphorus (P), titanium (Ti), zirconium (Zr), niobium (Nb), and tantalum (Ta), while examples of down-dopant materials include fluorine (F) and boron (B).

[0041] In this specification, the "chromatic dispersion" of a waveguide fiber, unless otherwise noted, is simply referred to as "dispersion," and is the sum of material dispersion, waveguide dispersion, and intermode dispersion. In the case of a single-mode waveguide fiber, intermode dispersion is zero. The dispersion value for a two-mode type assumes that intermode dispersion is zero. The zero-dispersion wavelength (λ0) is the wavelength at which the dispersion value is zero. The dispersion gradient is the rate of change of dispersion with respect to wavelength.

[0042] "Effective cross-sectional area" is defined as follows:

[0043]

number

[0044] Here, f(r) is the transverse component of the electric field of the guided optical signal, and r is the position in the direction of radiation within the optical fiber. Where used herein, “effective cross-section” is used, i.e., “A eff Unless otherwise noted, " " refers to the effective optical cross-section at a wavelength of 1550 nm.

[0045] The term "α profile" (also called "alpha profile") refers to the relative refractive index profile, expressed in relation to Δ(r) with units of "%", where r is the radius, and follows the following equation:

[0046]

number

[0047] Here, r0 is the point where Δ(r) is maximized, r1 is the point where Δ(r) is zero, and r is r i ≦r≦r f It is within the range, and in this case, r i is the starting point of the alpha profile, r f This is the final point of the alpha profile, and alpha is a real number.

[0048] The mode field diameter (MFD) of an optical fiber is defined as follows:

[0049]

number

[0050] Here, f(r) is the transverse component of the electric field distribution of the guided optical signal, and r is the radiation direction position within the optical fiber. The "mode field diameter," or "MFD," is determined dependent on the wavelength of the optical signal, and unless otherwise noted, it is understood in this specification to refer to a wavelength of 1550 nm. The formulas for MFD described herein are valid for wavelengths of 1310 nm and 1550 nm.

[0051] The "trench amount" is defined as follows:

[0052]

number

[0053] Here, r Trench,inner is the inner radius of the trench region of the refractive index profile, and r Trench,оuter Δ is the outer radius of the trench region of the refractive index profile. Trench (r) is the relative refractive index of the trench region of the refractive index profile, and r is the radial position within the optical fiber. The trench quantity is an absolute and positive quantity, and in this specification, the units are %Δ square micron, %Δ- square micron (percent delta minus square micron), and %Δ-μm. 2 (Percent Delta minus Square Micrometer), or %Δμm 2 These units will be used interchangeably in this specification, but for that purpose, they may be used interchangeably.

[0054] The bending resistance of a waveguide fiber can be estimated by inductive attenuation under specified test conditions.

[0055] One type of bending test is the lateral load microbend test. In this so-called "lateral load" test, a waveguide fiber of a predetermined length is placed between two flat plates. A 70-gauge wire mesh is attached to one of the plates. A waveguide fiber of a known length is sandwiched between the two plates, and the reference attenuation is measured while both plates are pressed together with a force of 30 Newtons. Next, a force of 70 Newtons is applied to both plates, and the increase in attenuation, measured in dB / m, is measured. This increase in attenuation is the lateral load wire mesh (LLWM) attenuation of the waveguide.

[0056] Another type of bending test measures the attenuation of an optical fiber due to macrobending. More specifically, the bending resistance of a waveguide fiber can be estimated by the induced attenuation under given test conditions, for example, by arranging, i.e., winding, an optical fiber around a core rod of a given diameter, specifically by winding it once around a core rod of one of the following diameters: 10 mm, 20 mm, 30 mm, or similar diameters (e.g., "macrobend loss per turn × 10 mm diameter" or "macrobend loss per turn × 20 mm diameter"), and then measuring the increase in attenuation per turn.

[0057] The "pin array" bending test is used to compare the relative resistance of waveguide fibers to macrobend loss. To perform this test, the attenuation loss of a waveguide fiber, which is essentially free of induced bending loss, is measured. Next, the waveguide fiber is stretched around a pin array and the attenuation is measured again. The loss induced by bending is the difference between the two measured attenuations. The pin array consists of a set of 10 cylindrical pins arranged in a row and held in a fixed vertical position on a flat surface. The spacing between the pins is 5 mm from center to center. The pin diameter is 0.67 mm. During the test, sufficient tension is applied to allow the waveguide fiber to conform to a portion of the pin surface.

[0058] The theoretical fiber cutoff wavelength, or "theoretical fiber cutoff," or "theoretical cutoff," is the wavelength beyond which the induced light cannot propagate in a given mode. The mathematical definition can be found in Jeunhomme's *Single Mode Fiber Optics*, pp. 39-44, published by Marcel Decca, New York, in 1990, where theoretical fiber cutoff is described as the wavelength beyond which the mode propagation constant is equal to the plane wave propagation constant within the outer cladding.

[0059] Effective fiber cutoff is lower than theoretical cutoff due to losses induced by bending, mechanical pressure, or both. In this context, cutoff refers to the higher of the LP11 and LP02 modes. While the difference between LP11 and LP02 is generally not significant in measured values, both are clearly visible as multi-step differences in spectral measurements (when using multimode reference techniques), meaning that no output is observed at wavelengths longer than the measured cutoff. Actual fiber cutoff can be obtained by measuring the "fiber cutoff wavelength" using the standard 2m fiber cutoff test, i.e., the optical fiber test procedure FOTP-80 (Electronics Industry Union / Telecommunications Industry Association standard EIA-TIA-455-80), which is also known as "2m fiber cutoff" or "measured cutoff." Performing the FOTP-80 standard test results in either removing higher-order modes using a controlled amount of bending, or making the standard spectral response of the optical fiber the spectral response of a multimode fiber.

[0060] The cable break wavelength, or "cable break," is typically lower than the measured fiber break due to higher levels of bending and mechanical pressure in the cable environment. Actual cable conditions can be approximated by the cable break test described in the Electronics and Electronics Industries Union (EIA) standard EIA-445 Optical Fiber Test Procedure (FOTP), which is part of the EIA-TIA optical fiber standards, i.e., the Electronics and Electronics Industries Union / Telecommunications Industry Association optical fiber standards, and is more widely known as the FOTP standard. Measurement of cable break is described in EIA-455-170 Cable Break Wavelength for Single-Mode Fiber at Transmitting Power, i.e., "FOTP-170". Unless otherwise noted herein, optical properties (dispersion, dispersion gradient, etc.) are reported for LP01 mode.

[0061] The bending resistance of an optical fiber can be estimated by the attenuation induced by bending under specified test conditions. In this specification, bending loss is determined by a core-rod winding test. In the core-rod winding test, a fiber is wound around a core rod of a specified diameter, and the attenuation of the fiber in the winding configuration at a wavelength of 1550 nm is determined. Bending loss is reported as the increase in attenuation of the fiber in the winding configuration compared to the attenuation of the fiber in a non-winding (straight) configuration. In this specification, bending loss is reported in units of dB / turn, where one turn corresponds to one winding of the fiber around the outer circumference of the core rod.

[0062] The ratio of the mode field diameter (MFD) at a wavelength of 1550 nm to the cable cutoff wavelength (MFD at 1550 nm / cable cutoff wavelength, in μm) is defined herein as MACC.

[0063] A waveguide fiber communication link, or simply a link, consists of an optical signal transmitter, an optical signal receiver, and one or more waveguide fibers of a certain length, each fiber optically connected to the transmitter and receiver at both ends to propagate optical signals between them. The length of the waveguide fiber is composed of several shorter lengths, which can be joined together by arranging their ends in series and staggering or joining them. The link may also be provided with other optical components, such as optical amplifiers, optical attenuators, optical isolators, optical switches, optical filters, multiplexers, or demultiplexers. A group of interconnected links may also be referred to as a communication system.

[0064] A span of optical fiber as used herein includes one or more optical fibers of a certain length fused together in series, which extend between optical devices, for example, between two optical amplifiers or between a multiplexer and an optical amplifier. A span may include one or more segments of optical fiber as disclosed herein, and may further include one or more other segments of optical fiber selected to achieve desired system performance or parameters, such as residual dispersion near the ends of the span.

[0065] Figure 1 illustrates a cross-sectional view of one embodiment of the optical fiber of the present invention, and is generally referred to as reference number 10 throughout the document. The optical fiber 10 has a central fiber axis 22 (the center line of the optical fiber 10, which defines the radial position r=0). The waveguide fiber 10 has a core 12, and its effective cross-sectional area (A eff ) is 70 μm at a wavelength of 1550 nm 2 More broadly (at a wavelength of 1550 nm, for example, 70 μm) 2 or 110 μm 2 , 75μm 2 or 104 μm 2 , or 75 μm 2 or 97 μm 2The α value is in the range of 1.5 ≤ α ≤ 10. The waveguide fiber 10 comprises a cladding 20 surrounding the core. In some embodiments, an intervening layer or region may be present between the core and the cladding. The refractive index profile of the core region is preferably designed to minimize attenuation loss.

[0066] As will be further explained below, the relative refractive index of the core region and the relative refractive index of the cladding region may be different. Each of the above regions may be formed from silica glass or silica-based glass. Silica-based glass is silica glass that has been treated with impurities of one or more elements, i.e., modified silica glass. The variation in refractive index may be achieved by incorporating up-dopant or down-dopant at a level known to produce the target refractive index or refractive index profile using various techniques well known to those skilled in the art. Up-dopant is a doping agent that increases the refractive index of the glass compared to a glass composition that has not been treated with impurities using a doping agent. Down-dopant is a doping agent that decreases the refractive index of the glass compared to a glass composition that has not been treated with a doping agent. In one embodiment, the glass that has not been treated with impurities using a doping agent is pure silica glass. When the glass that has not been treated with impurities using a doping agent is pure silica glass, examples of up-dopant include Cl, Br, Ge, Al, P, Ti, Zr, Nb, Ta, etc., and examples of down-dopant include F, B, etc. Regions with a constant refractive index may be formed without impurity doping, or they may be formed by impurity doping at a uniform concentration. There is a risk that regions with varying refractive indices may be formed due to the non-uniform spatial distribution of the doping agent.

[0067] The core forms the central portion of the optical fiber and is generally cylindrical in shape. Furthermore, the cladding region is generally annular in shape. The annular region can be characterized in terms of its inner and outer radii. In this specification, radial positions r1 and r2 refer to the outermost radius of the first core region and the outermost radius of the second core region, respectively. When two regions are directly adjacent to each other, the outer radius of the inner region coincides with the inner radius of the outer region. In one embodiment, for example, the fiber includes a first core region. In such an embodiment, radius r1 coincides with the outer radius of the first core region.

[0068] Figure 2 schematically shows the refractive index profile (relative refractive index Δ with respect to radius) of a specific example of this fiber. Figure 2 shows the relative refractive index profile of a fiber having a first core region 16 that extends from radial position r0 to radial position r1 and has a relative refractive index of Δ1, and a second core region 18 that extends from radial position r1 to radial position r2 and has a relative refractive index of Δ2. In the profile, the first core region 16 has the highest relative refractive index.

[0069] In the embodiment shown in Figure 2, the core 12 consists of a first core region 16 and a second core region 18 that surrounds and is directly adjacent to the first core region 16. As used herein, "directly adjacent" means being in direct physical contact, and direct physical contact refers to a relationship of touching.

[0070] Depending on the embodiment, the core 12 may not contain germanium (Ge).

[0071] The first core region 16 has an α value in the range of 1.5 ≤ α ≤ 10 (e.g., 2 ≤ α ≤ 8, 1.5 ≤ α ≤ 6, 1.5 ≤ α ≤ 4.5, 2 ≤ α ≤ 4, or 2 ≤ α ≤ 3.5) and extends to the outer radius r1, in which case 2.5 μm ≤ r1 ≤ 8 μm is preferred, with 3 μm ≤ r1 ≤ 7 μm being preferred, but 3.5 μm ≤ r1 ≤ 6 μm being more preferred. The first core region 16 also exhibits a relative refractive index percentage profile Δ1(r) measured relative to pure silica and expressed in units of %, with the minimum relative refractive index Δ 1MIN and maximum relative refractive index Δ 1MAX The range (a) of the relative refractive index Δ1 measured at a radius r=2μm is -0.15≦Δ1(r=2μm)≦0.1. In some embodiments, it may be -0.08≦Δ1(r=2μm)≦0.1 or -0.15%≦Δ1(r=2μm)≦0.05. In some embodiments, Δ 1MAX =Δ1 (r=2μm). Depending on the embodiment, -0.35%≦Δ 1MIN Some values ​​are ≤ -0.05%, for example, -0.3% ≤ Δ 1MIN ≤ -0.1%, or -0.35% ≤ Δ 1MIN It may also be ≤ -0.1%.

[0072] In some embodiments, the second core region 18 is fluorinated. The second core region 18 surrounds and is directly adjacent to the first core region 16. Typically, according to each embodiment described herein, the second core region 18 contains 0.6% to 2.5% by weight of fluorine, for example, 0.6% to 2% by weight or 0.9% to 2% by weight.

[0073] The second core region 18 extends to a radius r2 in the range of 10 μm ≤ r2 ≤ 22 μm (e.g., 11 μm ≤ r2 ≤ 20 μm or 12 μm ≤ r2 ≤ 18 μm) and exhibits a negative relative refractive index percentage profile Δ2(r) measured relative to pure silica and expressed in units of %. The relative refractive index Δ2 may be set to be less than or equal to the relative refractive index Δ1 of the first core region 16 so that the second core region 18 forms a trench in the relative refractive index profile of the core 12. As used herein, the term “trench” refers to the region of the core 12 surrounded by the first core region 16 and the cladding 20 in a radial cross-section. The cladding refractive index is set to a reference point of 20 microns (μm), and the calculation of the trench amount is based on the 20 micron (μm) cladding refractive index reference point. In some embodiments, the trench amount V of the second core region 18 is 14%Δμm 2 In some embodiments, the trench amount V of the second core region 18 is 0%Δμm 2 or 8%Δμm 2 In some embodiments, the trench amount V of the second core region 18 is 4%Δμm 2 or 8%Δμm 2 In some embodiments, the trench amount V of the second core region 18 is 4%Δμm 2 or 6%Δμm 2 This can also be the case.

[0074] Minimum relative refractive index percentage Δ 2MIN The range (a) is Δ 2MIN ≤Δ1 (r=2μm) and Δ 2MIN ≤Δ 1MIN In some preferred embodiments, -0.47% ≤ Δ 2MIN ≤ -0.3%, and in each other preferred embodiment, -0.46% ≤ Δ 2MIN ≤ -0.36%. For example, Δ 2MIN This can be -0.29%, -0.3%, -0.35%, -0.38%, -0.4%, -0.42%, -0.47%, or any value between these numbers. It should be noted that in at least some embodiments, -0.35% ≤ Δ2(r=r1) ≤ -0.05%.

[0075] The second core region 18 has a relatively flat refractive index profile Δ 2MAX -Δ 2MIN It should be noted that when ≤0.03%, the radius r2 is defined as coinciding with the beginning of cladding 20. In some specific cases, the second core region 18 is Δ at radius r2 immediately before the beginning of cladding 20. 2MIN It reaches the value.

[0076] In some embodiments, the ratio r2 / r1 satisfies 1 ≤ r2 / r1 ≤ 9. It is recommended that r1 ≤ 8 μm and r2 ≤ 20 μm. In some embodiments, the ratio may also satisfy 2.5 ≤ r2 / r1 ≤ 5 (or 0.2 ≤ r1 / r2 ≤ 0.4).

[0077] Cladding 20 surrounds core 12, and the relative refractive index percentage Δ3(r), measured relative to pure silica and expressed in units of %, is Δ3(r) ≥ Δ 2MIN This indicates that, in which case the cutoff is 1260 nm or less. Depending on the embodiment, if the cutoff is 1530 nm or less, Δ3(r) is Δ2 or less. In some specific embodiments, Δ3(r) ≥ Δ 2MIN In some specific embodiments, Δ3(r)≧Δ 2MAX Clad 20 has a minimum relative refractive index percentage Δ 3MIN -0.4% ≤ Δ 3MIN It is recommended to indicate a range of ≤-0.2%. Depending on the embodiment, Δ 3MIN In some cases, the concentration is less than -0.4%. The cladding 20 extends to a radius r3. In some specific embodiments, the core 12 and cladding 20 contain fluorine (F) as a down dopant. The amount of fluorine in the first core region 16 and in the second core region 18 is recommended to increase with increasing radius. The fluorine concentration can be increased from 0% by weight to 2.0% by weight, but is more recommended to increase from 0% by weight to 1.8% by weight, for example, from 0% by weight to 1.6% by weight.

[0078] In some specific embodiments, the core 12 contains at least one alkali metal oxide doping agent, such as potassium (K), sodium (Na), lithium (Li), cesium (Cs), or libedium (Rb). In some specific embodiments, the core 12 contains K2O in an amount of 5 ppm to 1000 ppm by weight of potassium (K), with amounts between 5 ppm and 500 ppm by weight of potassium being more preferred, and amounts between 5 ppm and 300 ppm by weight of potassium being most preferred. The optical fiber 10 may contain chlorine. The amount of chlorine in the core 12 is preferably less than 3500 ppm by weight, and also less than 500 ppm by weight in the cladding 20. In some embodiments, the optical fiber may have a chlorine (Cl) doped core, in which case the chlorine in the first core region 16 is 1500 ppm to 10000 ppm, or 1500 ppm to 3500 ppm. Because a chlorinated core will have an increased refractive index based on the amount of chlorine added, each section around the optical fiber will be adjusted accordingly to the core. Unless otherwise specified, the term "ppm" refers to parts per million by weight, or ppm by weight, and weight-based measurements can be converted to ppm by multiplying by 1 / 10,000.

[0079] The relative refractive index profile of the optical fiber 10 is selected to result in an attenuation of 0.17 dB / km or less at a wavelength λ of 1550 nm, for example, an attenuation of 0.145 dB / km to 0.17 dB / km at a wavelength λ of 1550 nm, but 0.145 dB / km to 0.165 dB / km is more recommended, and 0.145 dB / km to 0.160 dB / km is the most recommended. The attenuation value should be 0.15 dB / km to 0.17 dB / km, or 0.145 dB / km to 0.165 dB / km at a wavelength λ of 1550 nm, but may also be, for example, 0.149 dB / km, 0.15 dB / km, 0.152 dB / km, 0.153 dB / km, 0.155 dB / km, 0.158 dB / km, 0.16 dB / km, 0.162 dB / km, 0.165 dB / km, 0.168 dB / km, or 0.17 dB / km.

[0080] In at least some embodiments, the optical fiber has a zero-dispersion wavelength λ0 such that 1300 nm ≤ λ0 ≤ 1324 nm. In at least some embodiments, the optical fiber has a mode field diameter (MFD) of 8.6 microns (μm) to 9.7 microns (μm) at a wavelength of 1310 nm. In at least some embodiments, the optical fiber has a mode field diameter (MFD) of 9.9 microns (μm) to 11 microns (μm) at a wavelength of 1550 nm. In at least some embodiments, the optical fiber has a cable breakout of less than 1530 nm. In at least some embodiments, the optical fiber has a cable breakout of less than 1260 nm.

[0081] In some embodiments, when the fiber is wound around a 30 mm diameter core, the macrobend loss at a wavelength of 1550 nm is less than 0.75 dB / turn. In some embodiments, when the fiber is wound around a 40 mm diameter core, the macrobend loss at a wavelength of 1550 nm is less than 0.5 dB / turn. In some embodiments, when the fiber is wound around a 50 mm diameter core, the macrobend loss at a wavelength of 1550 nm is less than 0.05 dB / turn. In some embodiments, when the fiber is wound around a 60 mm diameter core, the macrobend loss at a wavelength of 1550 nm is less than 0.005 dB / turn.

[0082] Figure 3 shows the relative refractive index profiles of three specific single-mode optical fibers according to one embodiment of the present disclosure. The graph for fiber ULLP0 shows a modeled trench amount of 14.5%Δμm 2 The relative refractive index profile of the comparative example fiber is shown. The graph for fiber ULLP1 shows a modeled trench amount of 8.75%Δμm 2 The disclosure presents the relative refractive index profile of a certain fiber. The graph for fiber ULLP2 shows a modeled trench amount of 6.36%Δμm 2 The relative refractive index profile of the fiber disclosed in this document is shown. The graph for fiber ULLP3 shows a modeled trench amount of 4.16%Δμm 2 The relative refractive index profiles of certain fibers as disclosed herein are shown. In the profiles of fibers ULLP1, ULLP2, and ULLP3, a lower trench amount is achieved by reducing the second interface area compared to the comparative profile of fiber ULLP0. Tables 1, 2, and 3 show trench amounts of 14%Δμm. 2 The optical properties of fiber 1 through fiber 12 in the following specific example are listed below.

[0083] [Table 1]

[0084] [Table 2]

[0085] [Table 3]

[0086] The fiber core and cladding of the present invention can be manufactured in a single-step or multi-step operation by various methods well known in the art. Suitable methods include flame combustion, flame oxidation, flame hydrolysis, external vapor deposition (OVD), internal vapor deposition (IVD), vapor-phase deposition (VAD), double crucible method, rod-in-tube method, cane-in-soot method, and impurity-doped silica deposition method. Various chemical vapor deposition (CVD) methods are well known and suitable for manufacturing the core and cladding regions used in the optical fibers of the present invention. These include external vapor deposition, axial vapor deposition, modified chemical vapor deposition (MCVD), internal vapor deposition, and plasma chemical vapor deposition (PECVD).

[0087] Suitable precursors for silica include silicon chloride (SiCl4) and various organosilicon compounds. Organosilicon compounds include various silicon compounds containing carbon. Some organosilicon compounds may also contain oxygen, hydrogen, or both. Specific examples of organosilicon compounds include octamethylcyclotetrasiloxane (OMCTS), silicon alkoxides (Si(OR)4), organosilanes (SiR4), and Si(OR). x R 4-xExamples include, but here, R is a carbon-containing organic group or hydrogen, and R may be the same or different for each existing substance, provided that at least one R is a carbon-containing organic group. Precursors suitable for chlorine addition treatment include chlorine (Cl2), tetrachlorosilane (SiCl4), hexachlorodisilane (Si2Cl6), hexachlorodisiloxane (Si2OCl6), trichlorosilane (SiCl3H), carbon tetrachloride (CCl4), etc. Precursors suitable for fluorine addition treatment include fluorine (F2), tetrafluoromethane (CF4), tetrafluorosilane (SiF4), etc.

[0088] It will be apparent to those skilled in the art that various modifications and changes can be made without departing from the spirit or scope of the present invention. Since various combinations, various sub-combinations, and various modifications of the embodiments of the present disclosure incorporating the spirit and content of the present invention can be envisioned by those skilled in the art, the present invention should be construed to include all that falls within the scope of each claim of the appended claims and their equivalents.

[0089] Hereinafter, preferred embodiments of the present invention will be described item by item.

[0090] Embodiment 1 A single-mode optical fiber, the optical fiber, has an outer radius r1 satisfying 2.5 μm ≤ r1 ≤ 8 μm with an α value in the range of 1.5 ≤ α ≤ 10, and shows a relative refractive index percentage profile Δ1(r) measured relative to pure silica with the unit of %, and the minimum relative refractive index Δ 1MIN and the maximum relative refractive index Δ 1MAX and when the relative refractive index is measured at a radius r = 2 μm, -0.35 ≤ Δ 1MIN ≤ -0.05 in the first core region, surrounds the first core region and is directly adjacent thereto, extends to an outer radius r2 satisfying 10 μm ≤ r2 ≤ 22 μm, and shows a negative relative refractive index percentage profile Δ2(r) measured relative to pure silica with the unit of %, and the minimum relative refractive index percentage Δ2MIN is -0.47% ≤ Δ 2MIN ≤ -0.3% and the quantity V is 14%Δμm 2 or less in a second core region, surrounding the core, showing a relative refractive index percentage profile Δ3(r) measured relative to pure silica and with units of %, and the minimum relative refractive index Δ 3MIN is -0.45% ≤ Δ 3MIN ≤ -0.2% and having a cladding region, the optical fiber has a cable cutoff of less than 1260 nm, a mode field diameter at a wavelength of 1310 nm of 8.6 microns (μm) to 9.7 microns (μm), a mode field diameter at a wavelength of 1550 nm of 9.9 microns (μm) to 11 microns (μm), and an attenuation at a wavelength of 1550 nm of 0.17 dB / km or less.

[0091] Embodiment 2 In the optical fiber of Embodiment 1, the quantity V of the annular second core region is 0%Δμm 2 to 9%Δμm 2 is.

[0092] Embodiment 3 In the optical fiber of Embodiment 1, the quantity V of the annular second core region is 4%Δμm 2 to 9%Δμm 2 is.

[0093] Embodiment 4 In the optical fiber of Embodiment 1, the quantity V of the annular second core region is 2%Δμm 2 to 7%Δμm 2 is.

[0094] Embodiment 5 In the optical fiber of Embodiment 1, the quantity V of the annular second core region is 2%Δμm 2 to 9%Δμm 2 is.

[0095] Embodiment 6 In the optical fiber of Embodiment 1, when the optical fiber is wound around a 30 mm diameter core rod, it exhibits a macrobend loss of less than 0.75 dB / turn.

[0096] Embodiment 7 In the optical fiber of Embodiment 1, when the optical fiber is wound around a core rod with a diameter of 40 mm, it exhibits a macrobend loss of less than 0.5 dB / turn.

[0097] Embodiment 8 In the optical fiber of Embodiment 1, when the optical fiber is wound around a core rod with a diameter of 50 mm, it exhibits a macrobend loss of less than 0.05 dB / turn.

[0098] Embodiment 9 In the optical fiber of Embodiment 1, when the optical fiber is wound around a core rod with a diameter of 60 mm, it exhibits a macrobend loss of less than 0.005 dB / turn.

[0099] Embodiment 10 In the optical fiber of Embodiment 1, 1 ≤ r2 / r1 ≤ 9, r1 ≤ 8 μm, and r2 ≤ 20 μm.

[0100] Embodiment 11 In the optical fiber of Embodiment 1, 2.5 ≤ r2 / r1 ≤ 5.

[0101] Embodiment 12 In the optical fiber of Embodiment 1, the optical fiber exhibits a zero-dispersion wavelength λ0, where 1300 nm ≤ λ0 ≤ 1324 nm.

[0102] Embodiment 13 In the optical fiber of Embodiment 1, the optical fiber exhibits a microbend loss of 1 dB / km or less.

[0103] Embodiment 14 A single-mode optical fiber, wherein the optical fiber is The α value is in the range of 1.5 ≤ α ≤ 10 and extends to an outer radius r1 satisfying 2.5 μm ≤ r1 ≤ 8 μm, exhibiting a relative refractive index percentage profile Δ1(r) measured relative to pure silica and expressed in units of %, with a minimum relative refractive index Δ 1MIN and maximum relative refractive index Δ 1MAX It has such that when the relative refractive index is measured at a radius r=2μm, -0.35≦Δ 1MIN The first core region is ≤ -0.05, It surrounds the first core region in a ring shape and is directly adjacent to it, extending to an outer radius r2 satisfying 10 μm ≤ r2 ≤ 22 μm, exhibiting a negative relative refractive index percentage profile Δ2(r) measured relative to pure silica and expressed in units of %, with a minimum relative refractive index percentage Δ 2MIN -0.47% ≤ Δ 2MIN The value is ≤-0.3%, and the quantity V is 14%Δμm 2 The following is a second core area, The core is surrounded by a relative refractive index percentage profile Δ3(r) measured relative to pure silica and expressed in units of %, with a minimum relative refractive index percentage Δ 3MIN -0.55% ≤ Δ 3MIN It has a cladding region of ≤-0.3%, The optical fiber has a cable breakout of less than 1530 nm, a mode field diameter of 8.6 microns (μm) to 9.7 microns (μm) at a wavelength of 1310 nm, a mode field diameter of 9.9 microns (μm) to 11 microns (μm) at a wavelength of 1550 nm, and an attenuation of 0.17 dB / km or less at a wavelength of 1550 nm.

[0104] Embodiment 15 In the optical fiber of Embodiment 14, the amount V of the annular second core region is 0%Δμm 2 or 9%Δμm 2 That is the case.

[0105] Embodiment 16 In the optical fiber of Embodiment 14, the amount V of the annular second core region is 4%Δμm 2 or 9%Δμm 2 That is the case.

[0106] Embodiment 17 In the optical fiber of Embodiment 14, the amount V of the annular second core region is 2%Δμm 2 or 7%Δμm 2 That is the case.

[0107] Embodiment 18 In the optical fiber of Embodiment 14, the amount V of the annular second core region is 2%Δμm 2 or 9%Δμm 2 That is the case.

[0108] Embodiment 19 In the optical fiber of Embodiment 14, when the optical fiber is wound around a core rod with a diameter of 60 mm, it exhibits a macrobend loss of less than 0.005 dB / turn.

[0109] Embodiment 20 In the optical fiber of Embodiment 14, when the optical fiber is wound around a 30 mm diameter core rod, it exhibits a macrobend loss of less than 0.75 dB / turn.

[0110] Embodiment 21 In the optical fiber of Embodiment 14, when the optical fiber is wound around a core rod with a diameter of 40 mm, it exhibits a macrobend loss of less than 0.5 dB / turn.

[0111] Embodiment 22 In the optical fiber of Embodiment 14, when the optical fiber is wound around a core rod with a diameter of 50 mm, it exhibits a macrobend loss of less than 0.05 dB / turn.

[0112] Embodiment 23 In the optical fiber of Embodiment 14, 1 ≤ r2 / r1 ≤ 9, r1 ≤ 8 μm, and r2 ≤ 20 μm.

[0113] Embodiment 24 In the optical fiber of Embodiment 14, 2.5 ≤ r2 / r1 ≤ 5.

[0114] Embodiment 25 In the optical fiber of Embodiment 14, the optical fiber exhibits a zero-dispersion wavelength λ0, where 1300 nm ≤ λ0 ≤ 1324 nm.

[0115] Embodiment 26 In the optical fiber of Embodiment 14, the optical fiber exhibits a microbend loss of 1 dB / km or less. [Explanation of Symbols]

[0116] 10 Light Fire 12 cores 16. First Core Area 18. Second Core Area 20 Clad 22 Central fiber axis

Claims

1. A single-mode optical fiber, wherein the optical fiber is Outer radius r from the fiber's central axis １ A first core region extending to and surrounding the first core region and directly adjacent thereto with an outer radius r ２ A core including a second core region extending to, The core is surrounded by a cladding region, The first core region has an α value in the range of 1.5 ≤ α ≤ 10, and the outer radius r １ is 2.5 μm ≤ r １ The relative refractive index percentage profile Δ, measured relative to pure silica and satisfying the condition ≤ 8 μm, with the unit being %. １ (r) is shown, along with the minimum relative refractive index Δ １ＭＩＮ and maximum relative refractive index Δ １ＭＡＸ It has -0.35% ≤ Δ １ＭＩＮ ≤ -0.05%, The second core region has an outer radius r ２ such that 10 μm ≤ r ２ ≤ 22 μm, and shows a negative relative refractive index percentage profile Δ ２ (r) measured relative to pure silica and expressed in %, and a minimum relative refractive index percentage Δ ２ＭＩＮ such that -0.47% ≤ Δ ２ＭＩＮ ≤ -0.3%, and the quantity V is 14% Δμm ２ or less The cladding region is measured relative to pure silica and has a relative refractive index percentage profile Δ ３ (r) is shown, and the minimum relative refractive index Δ ３ＭＩＮ -0.45% ≤ Δ ３ＭＩＮ The value ≤ -0.2% is satisfied. The optical fiber is a single-mode optical fiber having a cable cutoff wavelength of less than 1260 nm, a mode field diameter of 8.6 microns (μm) to 9.7 microns (μm) at a wavelength of 1310 nm, a mode field diameter of 9.9 microns (μm) to 11 microns (μm) at a wavelength of 1550 nm, and an attenuation of 0.17 dB / km or less at a wavelength of 1550 nm.

2. The amount V in the second core region is 0%Δμm ２ or 9%Δμm ２ The single-mode optical fiber according to claim 1.

3. The single-mode optical fiber according to claim 1 or claim 2, wherein the optical fiber exhibits a macrobend loss of less than 0.5 dB / turn when wound around a core rod with a diameter of 40 mm.

4. 1 ≤ r ２ / r １ ≤9, r １ ≤8 μm, and also, r ２ A single-mode optical fiber according to any one of claims 1 to 3, wherein the thickness is ≤20 μm.

5. 2.5 ≤ r ２ / r １ A single-mode optical fiber according to any one of claims 1 to 3, wherein ≤ 5.

6. A single-mode optical fiber, wherein the optical fiber is Outer radius r from the fiber's central axis １ A first core region extending to and surrounding the first core region in an annular shape and directly adjacent thereto with an outer radius r ２ A core including a second annular core region extending to, The core is surrounded by a cladding region, The first core region has an α value in the range of 1.5 ≤ α ≤ 10, and the outer radius r １ is 2.5 μm ≤ r １ The relative refractive index percentage profile Δ, measured relative to pure silica and satisfying the condition ≤ 8 μm, with the unit being %. １ (r) is shown, along with the minimum relative refractive index Δ １ＭＩＮ and maximum relative refractive index Δ １ＭＡＸ It has -0.35% ≤ Δ １ＭＩＮ ≤ -0.05%, The second annular core region has an outer radius r ２ 10 μm ≤ r ２ A negative relative refractive index percentage profile Δ that satisfies the condition ≤22 μm and is measured relative to pure silica, with the unit being %. ２ (r) is shown, along with the minimum relative refractive index percentage Δ ２ＭＩＮ -0.47% ≤ Δ ２ＭＩＮ The value ≤ -0.3% is satisfied, and the quantity V is 14%Δμm ２ The following are available: The cladding region is measured relative to pure silica and has a relative refractive index percentage profile Δ ３ (r) is shown, and the minimum relative refractive index Δ ３ＭＩＮ -0.55% ≤ Δ ３ＭＩＮ The condition ≤ -0.3% is met. The optical fiber is a single-mode optical fiber having a cable cutoff wavelength of less than 1530 nm, a mode field diameter of 8.6 microns (μm) to 9.7 microns (μm) at a wavelength of 1310 nm, a mode field diameter of 9.9 microns (μm) to 11 microns (μm) at a wavelength of 1550 nm, and an attenuation of 0.17 dB / km or less at a wavelength of 1550 nm.

7. The amount V in the second annular core region is 0%Δμm ２ or 9%Δμm ２ The single-mode optical fiber according to claim 6.

8. The amount V in the second annular core region is 2%Δμm ２ or 9%Δμm ２ The single-mode optical fiber according to claim 6 or claim 7.

9. The single-mode optical fiber according to any one of claims 6 to 8, wherein the optical fiber exhibits a macrobend loss of less than 0.05 dB / turn when wound around a core rod with a diameter of 50 mm.

10. 1 ≤ r ２ / r １ ≤9, r １ ≤8 μm, and also, r ２ A single-mode optical fiber according to any one of claims 6 to 9, wherein the thickness is ≤20 μm.

11. 2.5 ≤ r ２ / r １ A single-mode optical fiber according to any one of claims 6 to 10, wherein ≤ 5.

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