# US 2018/0024291 A1 · Low bend loss single mode optical fiber with chlorine updoped cladding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024291 A1 - Document ID: US20180024291A1 - Status: Published application - Kind: A1 - Application number: 15/708,438 - Filed: 2017-09-19 - Published: 2018-01-25 - Earliest claimed: 2015-09-15 - Assignees: Corning Incorporated - Applicants: Corning Incorporated - Inventors: Dana Craig Bookbinder; Ming-Jun Li; Pushkar Tandon - Web page: https://patentgrep.com/patent/US20180024291A1 ## CPC - G02B 6/03627: {arranged - +} - G02B 6/02004: {characterised by the core effective area or mode field radius} - G02B 6/02014: {Effective area greater than 60 square microns in the C band, i.e. 1530-1565 nm} - G02B 6/02395: {Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture (G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104)} - G02B 6/0281: {Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core (G02B6/0288, G02B6/0286 take precedence)} - G02B 6/03644: {arranged - + -} - G02B 6/02009: {Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An optical fiber having both low macrobend loss and low microbend loss. The fiber has a central core region, a first (inner) cladding region surrounding the central core region and having an outer radius r2>16 microns and relative refractive index Δ2, and a second (outer) cladding region surrounding the first cladding region having relative refractive index, Δ3, wherein Δ1>Δ3>Δ2. The difference between Δ3 and Δ2 is greater than 0.12 percent. The fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and r1/r2 is greater or equal to 0.24 and bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn. ## Claims ### Claim 1 An optical fiber comprising: (i) a central core region having outer radius r1 and refractive index Δ1 (ii) a cladding surrounding the central core region, the cladding comprising: (a) a first cladding region having an outer radius 25 microns>r2>16 microns and relative refractive index Δ2, wherein the ratio of r1/r2 is larger than 0.24 and (b) a second cladding region surrounding the first cladding region and having a relative refractive index Δ3 and an outer radius r3, wherein the second cladding region comprises at least 1.25 wt % chlorine (Cl), and wherein Δ1>Δ3>Δ2, and wherein the difference between Δ3 and Δ2 is greater than 0.12%, and Δ3>0.12%; and said fiber exhibits a bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn. ### Claim 2 (depends on 1) The optical fiber of claim 1, wherein the difference between Δ3 and Δ2 is greater than 0.13%. ### Claim 3 (depends on 1) The optical fiber of claim 1, wherein the difference between Δ3 and Δ2 is between 0.12% and 0.25%. ### Claim 4 (depends on 1) The optical fiber of claim 1, wherein said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm. ### Claim 5 (depends on 1) The optical fiber of claim 1, wherein the central core region of said fiber exhibits an alpha less than 10. ### Claim 6 (depends on 1) The optical fiber of claim 1, said fiber further exhibiting a wire mesh covered drum microbend loss at 1550 nm which is less than or equal to 0.07 dB/km. ### Claim 7 (depends on 1) The optical fiber of claim 1, wherein the first cladding region contains less than 0.02 wt % fluorine. ### Claim 8 (depends on 1) The optical fiber of claim 1, wherein the first cladding region is essentially free of fluorine and germania. ### Claim 9 (depends on 1) The optical fiber of claim 1, wherein Δ3>Δ2 for a length extending from r2 to a radius of at least 30 microns. ### Claim 10 (depends on 1) The optical fiber of claim 1, wherein the volume of the first cladding region is |V2|>30% □micron2. ### Claim 11 (depends on 1) The fiber of claim 1, wherein said fiber exhibits an attenuation at 1550 nm which is less than or equal to 0.186 dB/km. ### Claim 12 (depends on 1) The optical fiber of claim 1, wherein said central core region comprises a maximum relative refractive index (Δ1) of greater than or equal to 0.70%. ### Claim 13 (depends on 1) The fiber of claim 1, wherein the optical fiber exhibits: MFD at 1310 nm>9 microns; cable cutoff wavelength<1260 nm; zero dispersion wavelength, □0, of 1300 nm≦□0≦1324 nm; bend loss at 10 mm diameter<1.5 dB/turn; bend loss at 15 mm diameter<0.5 dB/turn wherein the bend loss is macrobend loss and is measured at 1550 nm wavelength. ### Claim 14 (depends on 1) The fiber of claim 1, wherein the optical fiber exhibits: 1200 nmr2>16 microns and relative refractive index Δ2, wherein the ratio of r1/r2 is larger than 0.24, and (b) a second cladding region surrounding the first cladding region and having a relative refractive index Δ3 and an outer radius r3, wherein the second cladding region comprises at least 1.2 wt % chlorine (Cl), and wherein Δ1>Δ3>Δ2, and wherein the difference between Δ3 and Δ2 is greater than 0.12%, and Δ3>0.12%; and said fiber exhibits a bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn. Further comprising a third cladding region surrounding the second cladding region, the third region having a refractive index Δ4, wherein Δ3>Δ4, and wherein the difference between Δ3 and Δ4 is greater than 0.1%, and −0.02<Δ4<0.02. ### Claim 18 (depends on 17) The optical fiber of claim 17, wherein the third cladding region includes less than 1 wt % of chlorine. ### Claim 19 (depends on 17) The optical fiber of claim 17, wherein the third cladding region includes less chlorine than the second cladding region, or no chlorine. ### Claim 20 (depends on 19) The optical fiber of claim 19 wherein, the third cladding region has viscosity that is larger than the viscosity of the second cladding region by at least 0.1×107 Poise. ### Claim 21 (depends on 1) The optical fiber of claim 1, wherein the central core region of said fiber exhibits an alpha greater than or equal to 0.5 and less than or equal to 10. ### Claim 22 (depends on 17) The optical fiber of claim 17, wherein said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm. ### Claim 23 The optical fiber comprising: (i) a central core region having outer radius r1 and refractive index Δ1 (ii) a cladding surrounding the central core region, the cladding comprising: (a) a first cladding region having an outer radius 25 microns>r2>16 microns and relative refractive index Δ2, wherein the ratio of r1/r2 is larger than 0.24 and (b) a second cladding region surrounding the first cladding region and having a relative refractive index Δ3 and an outer radius r3, wherein the second cladding region comprises at least 1.21.25 wt % chlorine (Cl), and wherein Δ1>Δ3>Δ2 , and wherein the difference between Δ3 and Δ2 is greater than 0.12%, and Δ3>0.12%; and said fiber exhibits a bend loss at 1550 nm for a 15 mm diameter mandrel of less than 0.5 dB/turn, said fiber having a coating thereon and exhibiting a basketweave microbend loss at −60° C. at 1550 nm which is less than or equal to 0.05 dB/km. ### Claim 24 (depends on 22) The optical fiber of claim 22, said fiber further exhibiting a basketweave microbend loss at −60° C. at 1550 nm which is less than or equal to 0.01 dB/km. ### Claim 25 (depends on 22) The optical fiber of claim 22, said fiber further exhibiting a basketweave microbend loss at −60° C. at 1625 nm which is less than or equal to 0.05 dB/km. ### Claim 26 (depends on 22) The optical fiber of claim 22, said fiber further exhibiting a basketweave microbend loss at −60° C. at 1625 nm which is less than or equal to 0.01 dB/km. ### Claim 27 (depends on 22) The optical fiber of claim 22, wherein said coating comprises: a primary coating P having a Young's modulus 0.1 to 1 MPa; and a secondary coating S having a Young's modulus of 1400 MPa to 2500 MPa, wherein the secondary coating has an outer coating diameter of not greater than 242 microns. ### Claim 28 (depends on 22) The optical fiber of claim 22, wherein the second cladding region comprises at least 1.3 wt % chlorine (Cl). ### Claim 29 (depends on 1) The optical fiber of claim 1, wherein the volume of the first cladding region is |V2|>60% % Δmicron2. ### Claim 30 (depends on 23) The optical fiber of claim 23, wherein said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm.