# US 8,542,967 B2 · Depressed graded index multi-mode optical fiber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,967 B2 - Document ID: US8542967B2 - Status: Granted - Kind: B2 - Application number: 13/209,132 - Filed: 2011-08-12 - Published: 2012-02-16 - Granted: 2013-09-24 - Earliest claimed: 2010-08-12 - Assignees: Draka Comteq B.V. - Applicants: Frans Gooijer; Gertjan Krabshuis; Elise Regnier; Adrian Amezeua-Correa; Pieter Matthijsse; Denis Molin - Inventors: Frans Gooijer; Gertjan Krabshuis; Elise Regnier; Adrian Amezeua-Correa; Pieter Matthijsse; Denis Molin - Web page: https://patentgrep.com/patent/US8542967B2 ## CPC - 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)} - C03C 13/045: {Silica-containing oxide glass compositions} - G02B 6/0288: {Multimode fibre, e.g. graded index core for compensating modal dispersion} - G02B 6/03627: {arranged - +} - C03C 2201/31: containing germanium - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS ## Abstract A multi-mode optical waveguide fiber including a central core region having an outer radius surrounded by an inner cladding region having an outer radius, the inner cladding region having a lower index of refraction than the central core region, wherein both the central core and inner cladding regions are doped with fluorine, wherein the refractive index profile of the central core region is of the gradient index type and the central core region in the range of rε[0-ra] comprises germanium at a maximum concentration within the range of 0.5 percent by weight to 4.0 percent by weight taken at a given radius, wherein said fiber has an Overfilled Modal Bandwidth >500 MHz·km at a wavelength of 850 nm and 1300 nm, according to IEC 60793-2-10. ## Claims ### Claim 1 A multi-mode optical waveguide fiber comprising a central core region having an outer radius ra, surrounded by an inner cladding region having an outer radius ric, said inner cladding region having a lower index of refraction than said central core region such that the fiber is depressed, wherein both the central core region and the inner cladding region are doped with fluorine, wherein the refractive index profile of the central core region is of the gradient index type and said central core region in the range of rε[0-ra] comprises germanium at a maximum concentration within the range of 0.5 percent by weight to 4.0 percent by weight taken at a given radius, wherein said fiber has an overfilled modal bandwidth >500 MHz.km at a wavelength of 850 nm and 1300 nm, according to IEC 60793-2-10, and wherein a maximum refractive index difference of the central core is substantially equal to zero. ### Claim 2 (depends on 1) The multi-mode optical waveguide fiber of claim 1, wherein the central core region comprises germanium at a concentration within the range of about 0.1 percent by weight to about 4.0 percent by weight taken at a given radius. ### Claim 3 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the concentration of germanium in the central core region is constant or varies substantially parabolically over the radial distance and decreases within the central core region from r=0 to r=ra, and remains substantially constant over the inner cladding region. ### Claim 4 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the concentration of fluorine increases as the radial distance increases from the central axis r=0 to the outer circumference of the central core region r=ra, wherein preferably the concentration of fluorine at r=ra is from 0.005% by weight to 7.0% by weight taken at radius ra. ### Claim 5 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the concentration of fluorine in the central core region varies substantially parabolically over the radial distance and increases within the central core region from r=0 to r=ra and remains preferably substantially constant over the inner cladding region. ### Claim 6 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the inner cladding region comprises germanium at a concentration within the range of 0.1 percent by weight to 4.0 percent by weight taken at a given radius. ### Claim 7 (depends on 6) The multi-mode optical waveguide fiber according to claim 6, wherein the inner cladding region comprises germanium at a concentration within the range of about 0.5 percent by weight to about 3.0 percent by weight. ### Claim 8 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the alpha (α) value of the gradient index type profile of said central core region is between 1.9-2.1. ### Claim 9 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein attenuation at 850 nm is less than 2.3 dB/km and/or wherein attenuation at 1310 nm is less than 0.6 dB/km. ### Claim 10 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the Numerical Aperture (NA) of the core is 0.200±0.015 and/or where the core radius ra is 25±2.5 μm. ### Claim 11 (depends on 9) The multi-mode optical waveguide fiber according to claim 9, wherein the bending loss at 850 nm and at 1300 nm for 100 turns around a cylinder of 75 mm diameter is <0.5 dB. ### Claim 12 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the inner cladding comprises one or more trenches, wherein each trench has a width of 2%-33% of the core radius ra, and/or wherein each trench has a depth Δnt with respect to the inner cladding of −5×10−3 to −1×10−3, and/or wherein the trench preferably is located between the core radius ra and the outer radius ric. ### Claim 13 (depends on 12) The multi-mode optical waveguide fiber according to claim 12, wherein the central core region and inner cladding region all comprise silica deposited via a plasma chemical vapor deposition process. ### Claim 14 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the fiber has an absolute change in attenuation of signal light at a range of 1200-1550 nanometers of less than 0.5 dB/km, for conditions wherein the fiber is maintained for 5 days at 70 degrees Centigrade in an inert atmosphere containing 1 vol. % hydrogen, and is annealed for 6 days at 70 degrees Centigrade in an atmosphere of air. ### Claim 15 (depends on 14) The multi-mode optical waveguide fiber of claim 14, further comprising an outer cladding surrounding the inner cladding, wherein the outer cladding has a higher refractive index than the inner cladding region and silica doped with one or more dopants, and wherein the outer cladding is preferably pure silica. ### Claim 16 (depends on 15) The multi-mode optical waveguide fiber of claim 15, wherein the outer cladding comprises a glass layer, obtained by an inside plasma deposition process. ### Claim 17 (depends on 1) The multi-mode optical waveguide fiber according to claim 1, wherein the outer radius ric of the inner cladding region is ric [Y1−62.5 μm], wherein Y1≧ra+5 μm, wherein 40 μm500 Mhz.km, wherein the fiber has an absolute change in attenuation at the range from 1200-1550 nm of less than 2 dB/km, after exposure to hydrogen (H2) in conditions wherein the fiber is maintained for 168 hours at 150 degrees Centigrade in 200 atm (2938 psi) of a gas containing 3 vol % hydrogen, and is annealed for 6 days at 70 degrees Centigrade in an atmosphere of air.