Patent ID: 9036972
Filing Date: 2015-05-19
Classification: C03B,C03C,G02B,Y02P,Y10T

Abstract:
1. An optical fiber preform, which is composed of silica-based glass, comprising: a core portion including a central ax containing an alkali metal at an average concentration of 5 atomic ppm or more; a first cladding portion having a refractive index lower than the core portion, disposed on the perimeter of the core portion, and having a OH group having a concentration of 200 mol ppm or more in the perimeter portion; and a second cladding portion having a refractive index lower than the core portion and disposed on the perimeter of the first cladding portion, wherein the concentration of the OH group in the perimeter portion of the first cladding portion is 2,000 mol ppm or more.