摘要:
An optical fiber includes a core section and a cladding section. A k value expressed by k=4Aeff/(πMFD2) is 1.08 or larger, Aeff being an effective area and MFD being a mode field diameter, at a wavelength of 1550 nm, a chromatic dispersion is in a range from +19.0 ps/nm/km to +21.9 ps/nm/km, and MFD is in a range from 10.3 μm to 13.0 μm. The inequality, r1
摘要:
An optical fiber includes a core section and a cladding section. A k value expressed by k=4Aeff/(πMFD2) is 1.08 or larger, Aeff being an effective area and MFD being a mode field diameter, at a wavelength of 1550 nm, a chromatic dispersion is in a range from +19.0 ps/nm/km to +21.9 ps/nm/km, and MFD is in a range from 10.3 μm to 13.0 μm. The inequality, r1
摘要:
An optical fiber preform has a core portion having a first core portion including a central axis, a second core portion disposed around the first core portion, and a third core portion disposed around the second core portion. The first core portion contains 10 atomic ppm or more of an alkali metal and 10 to 600 atomic ppm of chlorine, the second core portion contains 10 atomic ppm or less of the alkali metal and 10 to 600 atomic ppm of chlorine, and the third core portion contains 10 atomic ppm or less of the alkali metal and 2,000 atomic ppm or more of chlorine. An optical fiber has a core region doped with an alkali metal and chlorine, wherein the minimum concentration of chlorine in the core region is 1,000 atomic ppm or more, and the average concentration of the alkali metal therein is 0.2 atomic ppm or more.
摘要:
A method for the manufacture of an optical fiber preform for producing a low attenuation optical fiber with high yield, comprising preparing a core rod and adding a cladding region. At the step of preparing a core rod, the core rod is produced including a first core region with Cl density of less than 600 atm-ppm, a second core region with Cl density of less than 600 atm-ppm around the first core region, and a third core region with Cl density of 3000 atm-ppm or more around the second core region. An alkali metal is selectively added to the first core region among the first, second, and third core regions. A cladding region is formed around the core rod by heating at a temperature of 1200° C. or higher for 7 hours or less.
摘要:
There is provided a method for producing an optical fiber preform used in producing an optical fiber having low attenuation. The production method includes (1) a rod formation step of forming a glass rod of a silica glass containing an alkali metal element, the average concentration of the alkali metal element being 5 at·ppm or more, (2) a heat treatment step of heat-treating the glass rod, (3) a core part formation step of forming an alkali metal element-free silica glass layer having a chlorine concentration of 6000 at·ppm or more around the perimeter of the glass rod heat-treated in the heat treatment step to form a core part including the glass rod and the silica glass layer, and (4) a cladding part formation step of forming a cladding part of a silica-based glass having a lower refractive index than the core part around the perimeter of the core part.
摘要:
There is provided a method for producing an optical fiber having low attenuation, the optical fiber including a core that contains an alkali metal element. An optical fiber preform that includes a core part and a cladding part is drawn with a drawing apparatus to form an optical fiber, the core part having an average concentration of an alkali metal element of 5 atomic ppm or more. During the drawing, the time the temperature of glass is maintained at 1500° C. or higher is 110 minutes or less. The drawing speed is preferably 1200 m/min or more and more preferably 1500 m/min to 2300 m/min. The optical fiber preform preferably has a diameter of 70 mm to 170 mm and more preferably 90 mm to 150 mm.
摘要:
An optical fiber preform includes a core portion, in which the core portion includes an alkali-metal-doped core glass portion doped with an alkali metal, the maximum concentration of oxygen molecules in the core portion is 30 mol ppb or more, and the average concentration of the alkali metal in the core portion is 5 atomic ppm or more. A method of manufacturing an optical fiber preform includes an alkali-metal-doping step of doping a pipe composed of silica-based glass with an alkali metal, an oxygen-molecule-doping step of doping the glass pipe with oxygen molecules, and a collapsing step of collapsing the glass pipe by heating the glass pipe, in which the optical fiber preform is manufactured.
摘要:
There is provided a method for producing an optical fiber preform used in producing an optical fiber having low attenuation. The production method includes (1) a rod formation step of forming a glass rod of a silica glass containing an alkali metal element, the average concentration of the alkali metal element being 5 at·ppm or more, (2) a heat treatment step of heat-treating the glass rod, (3) a core part formation step of forming an alkali metal element-free silica glass layer having a chlorine concentration of 6000 at·ppm or more around the perimeter of the glass rod heat-treated in the heat treatment step to form a core part including the glass rod and the silica glass layer, and (4) a cladding part formation step of forming a cladding part of a silica-based glass having a lower refractive index than the core part around the perimeter of the core part.
摘要:
A method for producing an optical fiber preform according to the present invention includes an etching step of heating a silica-based glass tube using a heat source continuously traversed in the longitudinal direction of the glass tube to etch the inner surface portion of the glass tube containing impurities while an etching gas is allowed to flow into the glass tube. The glass tube has a maximum alkali metal concentration of 500 to 20,000 atomic ppm, a maximum chlorine concentration of 0 to 1000 atomic ppm, and a maximum fluorine concentration of 0 to 10,000 atomic ppm. In the etching step, the maximum temperature of the outer surface of the glass tube is in the range of 1900° C. to 2250° C., and the heating time is set to a time equal to or less than a time (min) given by ( 7 - alkai metal concentration ppm 5000 ) .
摘要:
An optical fiber having excellent strength that can be manufactured at low cost, as well as a method for making such optical fiber, is provided. An optical fiber 1 is a silica-based optical fiber comprising a core 11, an optical cladding 12 surrounding the core 11, and a jacketing region 13 surrounding the optical cladding 12 and having a uniform composition throughout from the internal circumference to the outer circumference. A compressive strained layer having a residual compressive stress is provided at the outermost circumference of the jacketing region 13.