US 12,466,757 B2
Production method for optical fiber base material, and optical fiber base material
Hirotaka Sakuma, Osaka (JP); and Yuki Kawaguchi, Osaka (JP)
Assigned to SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
Appl. No. 18/019,538
Filed by SUMITOMO ELECTRIC INDUSTRIES, LTD., Osaka (JP)
PCT Filed Aug. 27, 2021, PCT No. PCT/JP2021/031564
§ 371(c)(1), (2) Date Feb. 3, 2023,
PCT Pub. No. WO2022/050190, PCT Pub. Date Mar. 10, 2022.
Claims priority of application No. 2020-148202 (JP), filed on Sep. 3, 2020.
Prior Publication US 2023/0322605 A1, Oct. 12, 2023
Int. Cl. C03B 37/012 (2006.01); C03B 37/014 (2006.01)
CPC C03B 37/01211 (2013.01) [C03B 37/01228 (2013.01); C03B 37/014 (2013.01); C03B 2201/12 (2013.01); C03B 2201/20 (2013.01); C03B 2201/50 (2013.01); C03B 2203/22 (2013.01)] 12 Claims
OG exemplary drawing
 
1. A method for manufacturing an optical fiber preform made of silica-based glass, the method comprising:
forming a core portion; and
forming a cladding portion that has a refractive index lower than a refractive index of the core portion and surrounds the core portion,
wherein the forming the core portion comprises:
adding an alkali element group including an alkali metal element and an alkaline earth metal element to an inner surface of a glass pipe made of silica-based glass;
integrating the glass pipe and a glass rod disposed inside the glass pipe to form an integrated rod after the adding; and
applying a glass layer around the integrated rod, the glass layer having a refractive index higher than that of the cladding portion,
wherein a mean value of a mass fraction of chlorine in the glass layer is 100 ppm or greater and 2000 ppm or less.