Single-mode fiber with ultra low attenuation

Abstract

A single-mode fiber with ultralow attenuation includes a core layer and cladding layers. The cladding layers includes an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary cladding layer. The core layer has a radius of 3.9-4.8 m and a relative refractive index difference of 0.08% to 0.10%. The inner cladding layer has a radius of 9-14 m and a relative refractive index difference of 0.40% to 0.15%. The trench cladding layer has a radius of 13-25 m and a refractive index difference of 0.7% to 0.3%. The auxiliary outer cladding layer has a radius of 30-50 m and a relative refractive index difference of 0.4% to 0.15%. The outer cladding layer is a pure silicon dioxide glass layer.

Claims

1. A single-mode fiber with an ultralow attenuation, comprising: a core layer and cladding layers, wherein the cladding layers comprises an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary cladding layer; wherein the core layer is a germanium-doped silicon-dioxide glass layer, wherein a doping contribution of germanium is in a range of 0.02% to 0.10%; wherein the core layer has a radius r.sub.1 in a range of 3.9 to 4.7 m, and a relative refractive index difference n.sub.1 in a range of 0.08% to 0.10%; wherein the inner cladding layer has a radius r.sub.2 in a range of 9 to 14 m, and a relative refractive index difference n.sub.2 in a range of 0.35% to 0.15%; wherein the trench cladding layer has a radius r.sub.3 in a range of 13 to 25 m, and a relative refractive index difference n.sub.3 in a range of 0.7% to 0.3%; wherein the auxiliary outer cladding layer has a radius r.sub.4 in a range of 30 to 50 m, and a relative refractive index difference n.sub.4 in a range of 0.4% to 0.32%; wherein the outer cladding layer is a pure silicon dioxide glass layer; wherein a mode field diameter of the single-mode fiber at a wavelength of 1310 nm is in a range of 8.8 to 9.6 m; wherein a cable cut-off wavelength of the single-mode fiber is less than or equal to 1260 nm; wherein an attenuation of the single-mode fiber at a wavelength of 1310 nm is less than or equal to 0.304 dB/km; and wherein an attenuation of the single-mode fiber at a wavelength of 1550 nm is less than or equal to 0.174 dB/km.

2. The single-mode fiber according to claim 1, having a dispersion at a wavelength of 1550 nm being less than or equal to 18 ps/(nm*km), and a dispersion at a wavelength of 1625 nm being less than or equal to 22 ps/(nm*km).

3. The single-mode fiber according to claim 1, having a microbending loss at a wavelength of 1700 nm being less than or equal to 5 dB/km.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings illustrate one or more embodiments of the invention and together with the written description, serve to explain the principles of the invention. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment.

(2) FIG. 1 is a diagram of a refractive-index profile structure distribution according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) The invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals refer to like elements throughout.

(4) The terms used in this specification generally have their ordinary meanings in the art, within the context of the invention, and in the specific context where each term is used. Certain terms that are configured to describe the invention are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the invention. For convenience, certain terms may be highlighted, for example using italics and/or quotation marks. The use of highlighting has no influence on the scope and meaning of a term; the scope and meaning of a term is the same, in the same context, whether or not it is highlighted. It will be appreciated that same thing can be said in more than one way. Consequently, alternative language and synonyms may be used for any one or more of the terms discussed herein, nor is any special significance to be placed upon whether or not a term is elaborated or discussed herein. Synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only, and in no way limits the scope and meaning of the invention or of any exemplified term. Likewise, the invention is not limited to various embodiments given in this specification.

(5) It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only configured to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the disclosure.

(6) The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises and/or comprising, or includes and/or including or has and/or having when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

(7) Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

(8) As used herein, around, about or approximately shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term around, about or approximately can be inferred if not expressly stated.

(9) From a central axis of an optical fiber, according to changing of a refractive index, a layer closest to the axis is defined as a core layer, i.e., the core layer refers to a central area of a cross section of the fiber, and an outmost layer of the fiber, i.e., a pure-silicon-dioxide layer, is defined as an outer cladding layer of the fiber.

(10) As used herein, a relative refractive index difference n.sub.i of a layer of a fiber is defined according to the following formula:

(11) $n_i=\frac{n_i-n_c}{n_c}100\%$
where n.sub.i is a refractive index of the corresponding layer, and n.sub.c is a refractive index of the outer cladding layer, that is, a refractive index of the pure silicon dioxide.

(12) A contribution of doped Ge in the core layer of the optical fiber to the refractive index Ge is defined according to the following equation:

(13) $\mathrm{Ge}=\frac{n_{\mathrm{Ge}}-n_c}{n_c}100\%,$
where n.sub.Ge is a change of the refractive index of the silicon dioxide glass caused by the doped substance Ge doped in the core layer, provided that the doped substance Ge doped in the core layer is doped in the pure silicon dioxide that includes no other doped substance.

(14) Cable cut-off wavelength .sub.cc: As defined in the IEC (International Electrotechnical Commission) standard 60793-1-44, a cable cutoff wavelength .sub.cc is a wavelength for which an optical signal no longer transmits as a single-mode signal after transmitting about 22 meters in an optical fiber. During a test, the optical fiber needs to be bent/wound into a circle (one round) with a radius of about 14 cm and two circles (two rounds) with a radius of 4 cm to obtain data.

(15) The description will be made as to the embodiments of the present invention in conjunction with the accompanying drawings. In accordance with the purposes of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a single-mode fiber having an ultralow attenuation.

(16) According to one embodiment of the invention as shown in FIG. 1, the optical fiber includes a core layer and cladding layers surrounding the core layer.

(17) In certain embodiments, the cladding layers comprises an inner cladding layer surrounding the core layer, a trench cladding layer surrounding the inner cladding layer, an auxiliary outer cladding layer surrounding the trench cladding layer, and an outer cladding layer surrounding the auxiliary cladding layer.

(18) In certain embodiments, the core layer has a radius r.sub.1 in a range of about 3.9 to 4.8 m, and a relative refractive index difference n.sub.1 in a range of about 0.08% to 0.10%.

(19) In certain embodiments, the core layer is a germanium and fluorine co-doped silicon-dioxide glass layer, or a germanium-doped silicon-dioxide glass layer, where a doping contribution of germanium is in a range of about 0.02% to 0.10%.

(20) In certain embodiments, the inner cladding layer has a radius r.sub.2 in a range of about 9 to 14 m, and a relative refractive index difference n.sub.e in a range of about 0.40% to 0.15%. The trench cladding layer has a radius r.sub.3 in a range of about 13 to 25 m, and a relative refractive index difference n.sub.3 in a range of about 0.7% to 0.3%. The auxiliary outer cladding layer has a radius r.sub.4 in a range of about 30 to 50 m, and a relative refractive index difference n.sub.4 in a range of about 0.4% to 0.15%. The outer cladding layer is a pure silicon dioxide glass layer and has a radius of about 125 m.

(21) In certain embodiments, the single-mode fiber has a mode field diameter at a wavelength of about 1310 nm being in a range of about 8.8 to 9.6 m.

(22) In certain embodiments, the single-mode fiber has a cable cut-off wavelength being less than or equal to about 1260 nm.

(23) In certain embodiments, the single-mode fiber has a dispersion at a wavelength of about 1550 nm being less than or equal to about 18 ps/(nm*km), and a dispersion at a wavelength of about 1625 nm being less than or equal to about 22 ps/(nm*km).

(24) In certain embodiments, the single-mode fiber has an attenuation at a wavelength of about 1310 nm being less than or equal to about 0.324 dB/km, preferably, being less than or equal to about 0.304 dB/km.

(25) In certain embodiments, the single-mode fiber has an attenuation at a wavelength of about 1550 nm being less than or equal to about 0.184 dB/km, preferably, being less than or equal to about 0.174 dB/km.

(26) In certain embodiments, the single-mode fiber has a microbending loss at a wavelength of about 1700 nm being less than or equal to about 5 dB/km.

(27) Table 1 lists a refractive index profile parameters of the single-mode fiber in embodiments of the present invention, where Ge is a contribution of the doped Ge in the core layer to a refractive index. Table 2 shows corresponding optical transmission characteristic of the optical fibers listed in Table 1.

(28) TABLE-US-00001 TABLE 1 Optical fiber profile parameters of the optical fibers according to embodiments of the present invention Fiber r.sub.1 n.sub.1 r.sub.2 n.sub.2 r.sub.3 n.sub.3 r.sub.4 n.sub.4 number [m] [%] Ge [m] [%] [m] [%] [m] [%] 1 4.2 0.04 0.08 10 0.30 13.5 0.52 42 0.35 2 4.1 0.02 0.02 11.5 0.30 15.5 0.4 48 0.38 3 4.7 0 0.05 12.5 0.32 15.5 0.45 45 0.4 4 4.5 0.03 0.05 11 0.31 14.5 0.6 38 0.36 5 4.8 0.06 0.1 9 0.24 14 0.38 41 0.28 6 4.7 0.05 0.08 13 0.28 16 0.55 40 0.32 7 4 0 0.08 10 0.33 12.8 0.51 46 0.4 8 4.2 0.06 0.02 13 0.35 16.5 0.7 47 0.57 9 4.8 0.04 0.03 12 0.30 13.7 0.65 44 0.5 10 3.9 0.02 0.04 14 0.30 16.5 0.63 42 0.3

(29) TABLE-US-00002 TABLE 2 Optical fiber performance parameters of the optical fibers according to embodiments of the present invention Mode field Cable Attenuation Attenuation Fiber diameter cut-off Zero coefficient coefficient Microbending number @1310 wavelength dispersion @1310 nm @1550 nm @1700 nm 1 9 1242 1314 0.296 0.171 3 2 9.1 1206 1312 0.288 0.167 2.5 3 9.4 1231 1310 0.293 0.169 3.3 4 9.1 1254 1312 0.298 0.175 3.6 5 9.5 1237 1323 0.318 0.181 3.7 6 9.4 1250 1308 0.305 0.178 2.7 7 8.9 1222 1312 0.321 0.183 3.8 8 9.3 1258 1306 0.299 0.171 2 9 9.6 1231 1320 0.303 0.174 4.2 10 9.2 1246 1304 0.314 0.179 3.4

(30) According to the present invention, an attenuation parameter of the optical fiber is decreased, so that the optical fiber has ultralow attenuation performance. Comprehensive performance parameters such as a cutoff wavelength, a bending loss, and a dispersion of the optical fiber in the present invention are great in wavebands of applications, and are compatible with standard G.652. In addition, the wide trench cladding structure improves the bending loss of the optical fiber.

(31) The foregoing description of the exemplary embodiments of the invention has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

(32) The embodiments were chosen and described in order to explain the principles of the invention and their practical application so as to enable others skilled in the art to utilize the invention and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present invention pertains without departing from its spirit and scope. Accordingly, the scope of the present invention is defined by the appended claims rather than the foregoing description and the exemplary embodiments described therein.