OPTICAL FIBER, AND OPTICAL COMPONENT USING THE SAME OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To suppress the clad mode loss of an optical component having a grating formed in an optical fiber and to improve the connectivity with a single- mode optical fiber. SOLUTION: The outer circumferential side of a core 1 formed by adding GeO2 to quartz glass is covered with a 1st clad part 2 and the outer circumferential side of the 1st clad part 2 is covered with a 2nd clad part 3 of pure quartz so that the core 1 has a nearly stepped index type refractive index distribution. The 1st clad part 2 is formed by adding GeO2 having nearly the same density as the GeO2 addition density of the core 1 to quartz glass nearly uniformly in radial directions and adding a dopant (e.g. fluorine) decreasing the refractive index and has a >=0.45% a specific refractive index difference from that of the 2nd clad part 3 of the core 1. The cutoff wavelength of the optical fiber is set to 990 to 1370 nm and then leaky mode loss is reduced to suppress clad mode loss.