# US 10,768,384 B2 · High fiber density, low bend loss optical fiber cable > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,384 B2 - Document ID: US10768384B2 - Status: Granted - Kind: B2 - Application number: 16/440,175 - Filed: 2019-06-13 - Published: 2019-09-26 - Granted: 2020-09-08 - Earliest claimed: 2016-05-25 - Assignees: Corning Optical Communications LLC - Applicants: Corning Optical Communications LLC - Inventors: Dana Craig Bookbinder; Inna Igorevna Kouzmina; Ming-Jun Li; David Alan Seddon; Pushkar Tandon - Web page: https://patentgrep.com/patent/US10768384B2 ## CPC - G02B 6/441: {built up from sub-bundles (G02B6/4429, G02B6/4439, G02B6/4479 take precedence)} - G02B 6/4403: {with ribbon structure (G02B6/4429, G02B6/4439, G02B6/4479 take precedence)} - G02B 6/4432: {with fibre reinforcements} - G02B 6/4434: {Central member to take up tensile loads} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A highly packed, low bend loss optical cable is provided. The cable includes an outer cable jacket and a plurality of buffer tubes surrounded by the cable jacket. Each buffer tube includes an inner surface defining a channel having a diameter, D1, and an outer surface facing an inner surface of the cable jacket. The cable includes a plural number, N, of optical fibers, located within the channel of each buffer tube and surrounded by the inner surface of the buffer tube. Each optical fiber has an outer diameter, D2. The N optical fibers are densely packed within each buffer tube such that a diameter ratio parameter, Ω, is defined as the ratio D1/D2, and is 2.25+0.143(N)≤Ω≤1.14+0.313(N). ## Claims ### Claim 1 A densely packed, low bend loss optical fiber cable comprising: an outer cable jacket; a plurality of buffer tubes surrounded by the cable jacket, each buffer tube including an inner surface defining a channel and an outer surface facing an inner surface of the cable jacket; an inner group of at least one optical fiber located within the channel of each buffer tube; and an outer group of a plurality of optical fibers located within the channel of each buffer tube and surrounding the inner group; wherein the optical fibers of the outer group and inner group are packed within each buffer tube such that a maximum gap length measured between any pair of adjacent optical fibers of the outer group is less than an outer diameter of the at least one optical fiber of inner group such that the at least one optical fiber of the inner group is blocked from moving from the inner group to the outer group; wherein each of the optical fibers of the inner group and outer group comprise: a mode field diameter of larger than 9 microns at 1310 nm; a cable cutoff of less than 1260 nm; a macrobend loss of less than 0.5 dB/turn at 1550 nm for a mandrel diameter of 15 mm; and wherein each buffer tube has an inner diameter D1 and each optical fiber of both the outer group and the inner group has an outer diameter D2, wherein the total number of optical fibers in each buffer tube is a plural number, N, wherein the N optical fibers are densely packed within each buffer tube such that a diameter ratio parameter, Ω, is defined as the ratio D1/D2, and is 2.25+0.143(N)≤Ω≤1.14+0.313(N). ### Claim 2 (depends on 1) The optical fiber cable of claim 1, wherein 8 ≤N≤48. ### Claim 3 (depends on 2) The optical fiber cable of claim 2, wherein the N optical fibers are densely packed within each buffer tube such that Ω is less than 2.66+0.134(N). ### Claim 4 (depends on 3) The optical fiber cable of claim 3, wherein the plural number N of optical fibers within each buffer tube is 12, wherein the outer cable jacket has an outer diameter less than 15 mm, and D2 is less than 210 microns. ### Claim 5 An optical fiber cable comprising: an outer cable jacket surrounding a cable core; a plurality of buffer tubes surrounded by the cable jacket, each buffer tube including an inner surface defining a channel and an outer surface facing an inner surface of the cable jacket; an inner group of at least one optical fiber located within the channel of each buffer tube; and an outer group of a plurality of optical fibers located within the channel of each buffer tube and surrounding the inner group; wherein the optical fibers of the outer group and inner group are packed within each buffer tube such that a maximum gap length measured between any pair of adjacent optical fibers of the outer group is less than an outer diameter of the at least one optical fiber of inner group such that the at least one optical fiber of the inner group is blocked from moving from the inner group to the outer group; wherein each of the optical fibers of the inner group and outer group comprise: a mode field diameter of larger than 9 microns at 1310 nm; a cable cutoff of less than 1260 nm; a macrobend loss of less than 0.5 dB/turn at 1550 nm for a mandrel diameter of 15 mm; an outer diameter of less than 210 microns; and a wire-mesh covered drum microbending loss at 1550 nm of less than 0.03 dB/km. ### Claim 6 (depends on 5) The optical fiber cable of claim 5, wherein a fiber density in the cable core is from 3.49/mm2 and 17.64/mm2. ### Claim 7 (depends on 5) The optical fiber cable of claim 5, further comprising a central strength member. ### Claim 8 (depends on 5) The optical fiber cable of claim 5, wherein the buffer tube has a wall thickness between 50 microns and 250 microns. ### Claim 9 (depends on 5) The optical fiber cable of claim 5, wherein an overall number of optical fibers in the cable is from 72 to 288. ### Claim 10 (depends on 5) The optical fiber cable of claim 5, wherein the plurality of buffer tubes includes six to twelve buffer tubes. ### Claim 11 An optical fiber cable comprising: an outer cable jacket surrounding a cable core; a plurality of buffer tubes surrounded by the cable jacket, each buffer tube including an inner surface defining a channel and an outer surface facing an inner surface of the cable jacket; an inner group of at least one optical fiber located within the channel of each buffer tube; and an outer group of a plurality of optical fibers located within the channel of each buffer tube and surrounding the inner group; wherein the optical fibers of the outer group and inner group are packed within each buffer tube such that a maximum gap length measured between any pair of adjacent optical fibers of the outer group is less than an outer diameter of the at least one optical fiber of inner group such that the at least one optical fiber of the inner group is blocked from moving from the inner group to the outer group; wherein each of the optical fibers of the inner group and outer group comprise: a mode field diameter of larger than 9 microns at 1310 nm; a cable cutoff of less than 1260 nm; a macrobend loss of less than 0.5 dB/turn at 1550 nm for a mandrel diameter of 15 mm; and wherein the buffer tube has a wall thickness between 50 microns and 250 microns, the buffer tube is formed from a relatively rigid polymer material having a modulus of elasticity at 25° C. between 0.8 GPa and 3 GPa. ### Claim 12 (depends on 11) The optical fiber cable of claim 11, wherein a fiber density in the cable core is from 3.49/mm2 and 17.64/mm2. ### Claim 13 (depends on 11) The optical fiber cable of claim 11, each of the optical fibers has a wire-mesh covered drum microbending loss at 1550 nm of less than 0.03 dB/km. ### Claim 14 (depends on 11) The optical fiber cable of claim 11, wherein an overall number of optical fibers in the cable is from 72 to 288. ### Claim 15 (depends on 11) The optical fiber cable of claim 11, wherein the plurality of buffer tubes includes six to twelve buffer tubes.